ANALYSIS OF THE UNDERWATER EMISSIONS … of the Underwater Emissions from Outboard Engines i Abstract The development of Environmentally Adapted Lubricants (EALs) and their use has

AANNAALLYYSSIISS OOFF TTHHEE

UUNNDDEERRWWAATTEERR EEMMIISSSSIIOONNSS

FFRROOMM OOUUTTBBOOAARRDD EENNGGIINNEESS

Charles Kelly, B Eng (Hons)

This thesis is submitted for the award of the degree of Doctor of Philosophy,

in the School of Mechanical, Manufacturing and Medical Engineering,

Queensland University Technology, Brisbane, Australia.

April 2004

Erratum Research on the subject of outboard engine emissions has continued at QUT after the examination of this thesis. As a result a gross error factor of 655 was discovered. Essentially, each concentration with normalised concentration (ug/kWhr) should be increased by the above factor. A paper with the corrected results has been submitted to an international journal. The error does not effect the relative comparison made between emissions in the thesis nor the statistical analysis. However, comparison with other emission results or emission guidelines does require the correction to be applied.

Analysis of the Underwater Emissions from Outboard Engines

i

Abstract

The development of Environmentally Adapted Lubricants (EALs) and their use has been gaining momentum over the last decade. It has been shown that raw EALs degrade in the environment in about one tenth the time of an equivalent mineral based lubricant. Estimates and findings such as these serve to highlight the potential benefits of the EAL products, it is also important however to investigate the by-products of their use to ensure that the benefits are not cancelled by an increase of, for instance, combustion by-products. This thesis compares the emissions from a two-stroke outboard engine when using an EAL and an equivalent mineral lubricant, where the primary objective of the study is to characterise and quantify the pollutants that remain within the water column after combustion. To accomplish this, tests were conducted both in the laboratory (freshwater) and in the field (seawater) for a range of throttle settings. A 1.9kW two-stroke outboard engine was set-up in a test tank and water samples were taken from the tank after the engine had been run for a period at each of the throttle settings. The tests were repeated for a 5.9kW four-stroke engine, however, the experiments were only conducted in the laboratory (freshwater) and using only a standard mineral lubricant. Statistical analyses of the results were conducted using a Principal Components Analysis (PCA). A simple dilution model was used to estimate the initial outboard engine emission concentrations, which was extended to determine the concentrations at distances of 1, 10 and 100 metres from the source. An investigation of the Total Toxicity Equivalence of the PAH pollutant concentrations (TEQPAH) was conducted using Toxicity Equivalent Factors (TEFs). Results for both types of engine and in both fresh and seawater showed that even the initial concentrations at the source, in almost all instances, were well below the ANZECC water quality guidelines trigger levels. At a distance of 1 metre from the source all concentrations were well below, and therefore, the Total Toxicity Equivalents of the PAHs were found to be even lower. It is concluded that the emissions from a single outboard engine when using either an EAL or a mineral based lubricant are similar. However, the use of EALs has further reaching advantages in that spilt raw lubricants will degrade in the environment up to 10 times faster than a mineral lubricant. Also EALs are less toxic to aquatic and marine organisms and therefore the benefits of using them has to be viewed from a wider perspective. The results in this thesis for a single outboard engine now form the basis for a more detailed environmental assessment of their impacts.


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Table of Contents

ABSTRACT........................................................................................................................................... I TABLE OF CONTENTS ......................................................................................................................... II LIST OF FIGURES ............................................................................................................................... VI LIST OF TABLES ................................................................................................................................ IX NOMENCLATURE............................................................................................................................... XI ACRONYMS ..................................................................................................................................... XIII PUBLICATIONS ARISING FROM THE PROJECT....................................................................................XV ACKNOWLEDGEMENTS....................................................................................................................XVI SIGNED STATEMENT......................................................................................................................XVIII

CHAPTER 1 ......................................................................................................................................... 1

INTRODUCTION................................................................................................................................... 1 1.1 Background .................................................................................................................... 1 1.2 Aims and Objectives of the Project ................................................................................ 4

CHAPTER 2 ......................................................................................................................................... 6

LITERATURE REVIEW ......................................................................................................................... 6 2.1 Background .................................................................................................................... 6 2.2 The Two-Stroke Engine .................................................................................................. 9

2.2.1 How a Two-Stroke Engine Works ........................................................................................... 9 2.2.2 Advantages and Disadvantages of Two-Stroke Engines ....................................................... 10

2.3 Tribology ...................................................................................................................... 11 2.3.1 General Characteristics of Petroleum..................................................................................... 12 2.3.2 Types of Petroleum Products ................................................................................................. 12 2.3.3 Gasolines and Lubricating Oils .............................................................................................. 13 2.3.4 The General Fate of Hydrocarbons in the Marine Environment ............................................ 14 2.3.5 The Fuel/Oil Mixture as a Pollutant ....................................................................................... 15

2.3.5.1 Polycyclic Aromatic Hydrocarbons............................................................................. 15 2.3.5.2 Volatile Organic Compounds ...................................................................................... 28

2.3.6 Environmentally Adapted Lubricants .................................................................................... 31 2.4 Previous Studies Related to Marine Engine Testing .................................................... 33

2.4.1 European Studies ................................................................................................................... 34 2.4.2 Studies in the USA................................................................................................................. 36 2.4.3 Australian Studies .................................................................................................................. 39 2.4.4 Limitations within the Previous Studies................................................................................. 39

2.5 Engine Performance Modelling ................................................................................... 42 2.5.1 Two-Stroke Engine Performance Modelling.......................................................................... 44

2.6 Statistical Analyses....................................................................................................... 46 2.6.1 Chemometrics ........................................................................................................................ 46


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2.6.1.1 Principal Components Analysis................................................................................... 47

CHAPTER 3 ....................................................................................................................................... 50

EQUIPMENT AND METHODOLOGIES.................................................................................................. 50 3.1 Experimental Equipment and Set-Up – Engines .......................................................... 50 3.2 Fuel Consumption Tests ............................................................................................... 61

3.2.1 Procedure ............................................................................................................................... 61 3.3 Preliminary Pollutant Investigation ............................................................................. 62

3.3.1 Equipment and Procedure ...................................................................................................... 62 3.4 Two – Stroke Engine Laboratory Tests ........................................................................ 64

3.4.1 Equipment and Procedure ...................................................................................................... 64 3.5 Two – Stroke Engine Field Tests .................................................................................. 65

3.5.1 Field Test Site ........................................................................................................................ 65 3.5.2 Field Test Equipment and Procedure ..................................................................................... 66

3.6 Four – Stroke Engine Tests .......................................................................................... 67 3.6.1 Equipment.............................................................................................................................. 67 3.6.2 Procedure ............................................................................................................................... 67

3.7 PAH Identification and Quantification......................................................................... 67 3.7.1 Preparation of the Water Samples for Analysis...................................................................... 67 3.7.2 Extraction Procedure.............................................................................................................. 68 3.7.3 Sample Analysis..................................................................................................................... 69 3.7.4 Efficiency of the Extraction Procedure .................................................................................. 70 3.7.5 Calculations ........................................................................................................................... 70

3.8 VOC Identification and Quantification ........................................................................ 73 3.9 Raw Fuel and Oil Analyses .......................................................................................... 73 3.10 Engine Performance Modelling ................................................................................... 73 3.11 Statistical Analysis ....................................................................................................... 97

CHAPTER 4 ....................................................................................................................................... 98

RESULTS .......................................................................................................................................... 98 4.1 Fuel Consumption Tests ............................................................................................... 99

4.1.1 Two-Stroke Engine FC Tests – Laboratory............................................................................ 99 4.1.2 Two-Stroke Engine FC Tests – Field ................................................................................... 100 4.1.3 Four-Stroke Engine FC Tests – Laboratory ......................................................................... 101

4.2 Preliminary Pollutant Investigation Results............................................................... 101 4.3 Raw Fuel and Oil Results ........................................................................................... 102 4.4 Two - Stroke Engine Laboratory Test Results – PAHs............................................... 104 4.5 Two - Stroke Engine Laboratory Test Results – VOCs............................................... 107 4.6 Two - Stroke Engine Field Test Results – PAHs......................................................... 108 4.7 Four - Stroke Engine Laboratory Results – PAHs ..................................................... 110 4.8 Four - Stroke Engine Laboratory Results – VOCs ..................................................... 110 4.9 Two-Stroke Engine Performance Modelling .............................................................. 111 4.9 General Discussion .................................................................................................... 114


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CHAPTER 5 ..................................................................................................................................... 117

POLYCYCLIC AROMATIC HYDROCARBONS ANALYSIS FOR THE TWO-STROKE ENGINE.................. 117 5.1 Mineral vs. EAL Laboratory Tests PAH Results ........................................................ 118 5.2 Mineral vs. EAL Field Tests PAH Results .................................................................. 121 5.3 Fresh Water vs. Sea Water PAH Results - Mineral Oil.............................................. 124 5.4 Fresh Water vs. Sea Water PAH Results – EAL......................................................... 126 5.5 General Discussion .................................................................................................... 128

CHAPTER 6 ..................................................................................................................................... 130

VOLATILE ORGANIC COMPOUNDS ANALYSIS FOR THE TWO-STROKE ENGINE............................... 130 6.1 Mineral vs. EAL Laboratory Tests VOC Results ........................................................ 131 6.2 General Discussion .................................................................................................... 133

CHAPTER 7 ..................................................................................................................................... 135

COMPARISON OF THE TWO-STROKE AND FOUR-STROKE ENGINE EMISSIONS ................................ 135 7.1 PAH Results for the Two and Four Stroke Engines ................................................... 136 7.2 VOC Results for the Two and Four Stroke Engines ................................................... 139 7.3 General Discussion .................................................................................................... 141

CHAPTER 8 ..................................................................................................................................... 144

POLLUTANT DILUTIONS ................................................................................................................. 144 8.1 Dilution of the Fresh Water Laboratory PAH Results ............................................... 147 8.2 Dilution of the Fresh Water Laboratory VOC Results ............................................... 148 8.3 Dilution of the Sea Water PAH Results ...................................................................... 149 8.4 Dilution of the Four-Stroke Engine Test Results........................................................ 151 8.5 Two and Four-Stroke Engine Dilutions Comparisons ............................................... 152 8.6 General Discussion .................................................................................................... 155

CHAPTER 9 ..................................................................................................................................... 157

TOXICITY OF THE POLLUTANTS...................................................................................................... 157 9.1 General Discussion .................................................................................................... 160

CHAPTER 10 ................................................................................................................................... 162

CONCLUSIONS AND FUTURE RESEARCH......................................................................................... 162 10.1 Conclusions ................................................................................................................ 162 10.2 Future Research ......................................................................................................... 164

REFERENCES................................................................................................................................. 167

APPENDIX A – RESULTS OF THE PRELIMINARY POLLUTANT INVESTIGATION .... 172

APPENDIX B – SAMPLE CALCULATIONS.............................................................................. 175

APPENDIX C – POLLUTANT DILUTIONS ............................................................................... 179


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APPENDIX D: TWO-STROKE ENGINE PERFORMANCE MODELLING INPUT DATA. 183

APPENDIX E: POWER AND TORQUE DATA FOR THE HONDA OUTBOARD ENGINE187


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List of Figures

Figure 1: Diagrammatical Representation of the Naphthalene Molecule ........................................... 15

Figure 2: Diagrammatical Representation of the Anthracene and Phenanthrene Molecules ............. 16

Figure 3: Diagram of the Heavier PAH Molecules Pyrene and Benzo(a)pyrene ................................ 16

Figure 4: An Underwater Image of the Exhaust Gases being emitted from the Hub of an Outboard

Engine's Propeller ............................................................................................................... 41

Figure 5: Test Tank Tap....................................................................................................................... 51

Figure 6: Fuel Line Modifications (Rea, 2001) ................................................................................... 54

Figure 7: Two-Stroke Outboard Engine Test Rig - Rear View ............................................................ 55

Figure 8: Two-Stroke Outboard Engine Test Rig - Front View ........................................................... 55

Figure 9: Carburettor Throttle Pin Travel (Rea, 2001)....................................................................... 56

Figure 10: Throttle Setting Gauges (Rea, 2001).................................................................................. 57

Figure 11: Warm-Up Stand (Rea, 2001).............................................................................................. 58

Figure 12: Set-up of the Four-Stroke Engine Experimental Equipment for the Fuel Consumption and

Engine Tests ...................................................................................................................... 59

Figure 13: Four-Stroke Engine Throttle Settings on Tiller Arm – Side View ...................................... 60

Figure 14: Four-Stroke Engine Throttle Settings on Tiller Arm – Top View....................................... 60

Figure 15: Four-stroke Engine Warm-up Configuration..................................................................... 61

Figure 16: Set-up of the Two-Stroke Engine on a Small Timber Boat that was used for the In - Field

Fuel Consumption Tests.................................................................................................... 62

Figure 17: Shows the Location of the Test Site .................................................................................... 66

Figure 18: On Site Field Experiments in Progress .............................................................................. 67

Figure 19: The Dismantled Two-Stroke Engine ready for Component Measurement ......................... 74

Figure 20: Engine Configuration Data Box......................................................................................... 75

Figure 21: Basic Engine Dimension Data Box .................................................................................... 76

Figure 22: Ignition and Combustion Details Data Box ....................................................................... 77

Figure 23: Comparison of Output Power at Different Ignition Timing ............................................... 79

Figure 24: Ambient Condition Data Box ............................................................................................. 79

Figure 25: Fuel and Scavenge Details................................................................................................. 81

Figure 26: Comparison of Different Air-Fuel Ratios........................................................................... 86


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Figure 27: Run Parameters Data Box ................................................................................................. 86

Figure 28: Inlet Valve Detail Data Box ............................................................................................... 88

Figure 29: Image of the Reed Petal and Stop Plate ............................................................................. 89

Figure 30: Transfer Port Data Box...................................................................................................... 90

Figure 31: The Axial Attitude Angle .................................................................................................... 90

Figure 32: The Radial Attitude Angle .................................................................................................. 91

Figure 33: Exhaust Port Data Box....................................................................................................... 92

Figure 34: Diagram of a Typical Inlet Duct with Reed Valve ............................................................. 93

Figure 35: Inlet Duct Data Box ........................................................................................................... 94

Figure 36: Transfer 1 Duct Data Box .................................................................................................. 94

Figure 37: Exhaust Pipe and Box Muffler Data Box ........................................................................... 95

Figure 38: Exhaust System of the Outboard Engine ............................................................................ 96

Figure 39: the Power Curve Developed by the MOTA Software after the Modelling Exercise was

Undertaken...................................................................................................................... 112

Figure 40: Differences Between the Results of the Actual and Modelled Fuel Consumption Rates for

the Two-Stroke Engine .................................................................................................... 113

Figure 41: PCA Graph for the Comparison of the Lab Two-Stroke Engine Tests – Mineral vs. EAL121

Figure 42: PCA Graph for the Comparison of the Field Test Results – Mineral vs. EAL ................. 123

Figure 43: PCA Graph for the Comparison of the Laboratory and Field Test Results – Mineral Oil

............................................................................................................................................................ 125

Figure 44: PCA Graph for the Comparison of the Laboratory and Field Test Results – EAL .......... 127

Figure 45: PCA Graph for the Comparison of the Laboratory VOC Results .................................... 132

Figure 46: PCA Graph for the Comparison of the PAHs from both Engines .................................... 137

Figure 47: A Comparison of the Total PAH Emissions from the Two and Four-Stroke Engines ...... 138

Figure 48: A Comparison of the Total VOC Emissions from the Two and Four-Stroke Engines...... 140

Figure 49: Comparison of the Brake Specific Fuel Consumption for the Two and Four-Stroke Engines

............................................................................................................................................................ 141

Figure 50: A Schematic of the Two-Stroke Engine Cycle (Rea 2001)................................................ 141

Figure 51: Shows the Decay Rate for the Pollutant Concentrations with Distance from the Propeller

............................................................................................................................................................ 146


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Figure 52: The Concentrations of the Total PAH Pollutants at 100% Throttle vs. Distance from the

Source ............................................................................................................................. 152

Figure 53: The Concentrations of the Total VOC Pollutants at 100% Throttle vs. Distance from the

Source ............................................................................................................................. 153

Figure 54: Outboard Engine Passing Velocity Measuring Probe ..................................................... 154

Figure 55: Velocity Disturbance Caused by an Outboard Engine in Open Water ............................ 154

Figure 56: A Comparison of the TEQPAH between the Two and Four-Stroke Engines ...................... 160


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List of Tables

Table 1: Principle Petroleum Fractions from Fractional Distillation ................................................. 13

Table 2: Carcinogenic Potential of the Sixteen USEPA Priority PAH Pollutants ............................... 17

Table 3: USEPA PAH Priority Pollutants and their Australian Water Quality Guideline Trigger

Levels ..................................................................................................................................... 19

Table 4: The Range of VOC Pollutants Identified and their Australian Water Quality Guidelines

Trigger Levels ........................................................................................................................ 29

Table 5: Test Tank Volume Calibration ............................................................................................... 52

Table 6: Two-Stroke Engine Fuel Consumption Tests Conducted in the Laboratory.......................... 99

Table 7: Two-Stroke Engine RPM Tests Conducted in the Laboratory ............................................. 100

Table 8: Two-Stroke Engine Fuel Consumption Tests Conducted in the Field.................................. 100

Table 9: Two-Stroke Engine RPM Readings Conducted in the Field ................................................ 100

Table 10: Fuel Consumption Rates at the Throttle Various Settings for the Four-Stroke Engine ..... 101

Table 11: Engine RPM at the Various Throttle Settings for the Four-Stroke Engine........................ 101

Table 12: Summary of the Preliminary PAH Results ......................................................................... 102

Table 13: Summary of the Preliminary VOC Results......................................................................... 102

Table 14: PAH Pollutants in the Raw Fuel and Oils, and in the Fuel and Oil Mixtures ................... 103

Table 15: VOC Pollutants in the Raw Fuel and Oils, and in the Fuel and Oil Mixtures ................... 104

Table 16: PAH Pollutants Analysis when the Mineral Lubricant was used in the Laboratory Tests. 105

Table 17: PAH Pollutants Analysis when the EAL was used in the Laboratory Tests ....................... 106

Table 18: VOC Pollutants Analysis when the Mineral Lubricant was used in the Laboratory Tests 107

Table 19: VOC Pollutants Analysis when the EAL was used in the Laboratory Tank Tests.............. 108

Table 20: PAH Pollutants Analysis when the Mineral Lubricant was used for the Field Tests......... 109

Table 21: PAH Pollutants Analysis when the EAL was used for the Field Tests ............................... 109

Table 22: PAH Pollutants Analysis for the Four-Stroke Engine Tests Conducted in the Laboratory 110

Table 23: VOC Pollutants Analysis for the Four-Stroke Engine Tests Conducted in the Laboratory111

Table 24: Final Power Output Values used to Perform the Calculations for each of the Throttle

Settings and Both Lubricants............................................................................................. 113

Table 25: Emission Rates of the PAH Pollutants when using both Lubricants - Laboratory Tests ... 118

Table 26: Emission Rates of the PAH Pollutants when using both Lubricants - Field Tests............. 122


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Table 27: Emission Rates of the PAHs when using the Mineral Lubricant – Laboratory vs. Field Tests

............................................................................................................................................................ 124

Table 28: Emission Rates of the PAHs when using the EAL – Laboratory vs. Field Tests ................ 126

Table 29: Emission Rates of the VOC Pollutants when using both Lubricants - Laboratory Tests ... 131

Table 30: Emission Rates of the PAHs from both the Two and Four-Stroke Engines ....................... 136

Table 31: Emission Rates of the VOCs from both the Two and Four-Stroke Engines ....................... 139

Table 32: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the

Laboratory when using the Mineral Oil ............................................................................ 147

Table 33: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the

Laboratory when using the EAL......................................................................................................... 148

Table 34: Initial Concentrations of the VOC Pollutants for the Two-Stroke Engine Tests in the

Laboratory when using the Mineral Oil ............................................................................ 148

Table 35: Initial Concentrations of the VOC Pollutants for the Two-Stroke Engine Tests in the

Laboratory when using the EAL........................................................................................ 149

Table 36: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Field

when using the Mineral Oil ............................................................................................... 150

Table 37: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Field

when using the EAL........................................................................................................... 150

Table 38: Initial Concentrations of the PAH Pollutants for the Four-Stroke Engine Tests............... 151

Table 39: Initial Concentrations of the VOC Pollutants for the Four-Stroke Engine Tests............... 151

Table 40: The Different TEFs used by (Eljarrat et al., 2001), and used in this Study ....................... 158

Table 41: The Calculated TEQPAH using the Different TEFs and for the Two and Four-Stroke Engines

and the Fresh and Seawater Results.................................................................................. 159


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Nomenclature

A Disc area of the propeller (m2)

Bconc Detected concentration in the blank sample (μg/mL) •

C μg of pollutant emitted relevant to a particular sized engine per

second

Cactual Actual concentration in the test tank (μg/L)

Cb Corrected concentration in the blank water sample (μg/mL)

CD Diluted concentration

FCC& Amount of pollutant emitted per rate of fuel consumption (μg/L of

fuel consumed)

Cn Corrected concentration in the test water sample: n refers to the

throttle setting (μg/mL)

nC& Actual concentration in the test sample (μg/mL)

C0 Initial concentration of the pollutant (assumed to be evenly distributed

throughout the propeller disc area) (μg/kg)

tC Coefficient of Thrust

kCtan& Amended concentration in the test tank (μg/mL)

D Dilution factor

Dconc Detected concentration in the standard mixture (μg/mL)

E Emission rate of pollutant from experimental analysis (μg/kW.hr)

nE& Emission rate of particular pollutant at a particular throttle setting

(μg/kW.hr)

sf Propeller slip factor

FC Rate of fuel consumption at a particular throttle setting (mL/s)

k Initial concentration co-efficient = 6.74 * 10-4

Kconc Known concentration in the standard mixture (μg/mL)

m Decay exponent = -0.5 •

m Mass flow rate of water through the propeller (kg/s)

n Revolutions per second

η Mechanical efficiency of the drive train


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eryrecovη Recovery efficiency for the specific compound of interest

Nconc Detected concentration in the test sample (μg/mL)

p Propeller pitch

ρ Density of the water (kg/m3)

Pwr Engine output power at the particular throttle setting (kW)

T Length of the time of each test (s)

V Velocity of the water through the propeller (m/s)

Vextract Volume of the extracted sample (mL)

Vsample Volume of the water sample taken from the test tank (mL)

dx Down stream location divided by propeller diameter


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Acronyms

ADV Acoustic Doppler Velicometer

AGAL Australian Government Analytical Laboratories

AHH Aryl Hydrocarbon Hydroxylase

AIMS Australian Institute of Marine Science

ANZECC Australian and New Zealand Environment and Conservation Council

BDC Bottom Dead Centre

BOD Biological Oxygen Demand

BSFC Brake Specific Fuel Consumption

BTDC Below Top Dead Centre

BTEX Benzene, Toluene, Ethyl-Benzene, Xylene

CO Carbon Monoxide

CO2 Carbon Dioxide

COD Chemical Oxygen Demand

CH4 Methane

EAL Environmentally Adapted Lubricant

ESD Ecologically Sustainable Development

FC Fuel Consumption

FID Flame Ionisation Detector

GC Gas Chromatograph

HC Hydrocarbon

HP Hewlett Packard

LD50 Lethal Dose required to kill 50% of an experimental population

LLINCWA Loss Lubrication in Inland and Coastal Water Activities Project

NMHC Non-Methane Hydrocarbons

NOx Nitrogen Oxides – NO, NO2, etc

PAH Polycyclic Aromatic Hydrocarbon

PCA Principal Components Analysis

pH Hydrogen Ion Concentration

PM Particulate Matter

QUT Queensland University of Technology

RPM Revolutions Per Minute

SI Units Standard International Units


xiv

TDC Top Dead Centre

TEFs Toxicity Equivalency Factors

TEQPAH Total Toxicity Equivalent PAHs

USA United States of America

USEPA United States Environment Protection Agency

VOC Volatile Organic Compound


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Publications Arising from the Project Kelly, C. A., Brown, R. J., Rae, D., Scott, W. and Hargreaves, D. (2001), A Comparison of Mineral and Biodegradable Marine Two-Stroke Lubricants, In 2nd World Tribology Congress, Vienna, Austria. Kelly, C. A., Rasul, M. and Brown, R. J. (2001), Characterisation of Marine Two-Stroke Outboard Engine Emissions to Water, In 6th World Congress of Chemical Engineering, Melbourne, Australia. Kelly, C. A., Brown, R. J., Ayoko, G. A. and Scott, W. (2003), Underwater Emissions from a Two-Stroke Outboard Engine: Can the Type of Lubricant Make a Difference?, In National Environment Conference 2003, Brisbane, Australia. Kelly, C. A., Ayoko, G. A. and Brown, R. J. (2003), Under Water Emissions from a Two-Stroke Outboard Engine: A Comparison between an EAL and an Equivalent Mineral Lubricant, In 2nd International Conference on Tribology in Environmental Design 2003, Bournemouth, United Kingdom. Loberto, A., Brown, RJ. & Kelly, CA, (2003) A simple empirical model of two-stroke outboard motor pollutant dispersion based on laboratory experiments of propeller dispersion. Institution of Engineers Australia National Environment Conference, 18-20 June, Brisbane. Loberto, A.R., Brown, R.J., & Kelly, C.A., 2003. Assessing environmental impacts of two-stroke outboard motor lubricants using tank testing and simple dispersion model. pp 3-12, 2nd International Conference Tribology in Environmental Design 2003, 8th-10th September 2003, Bournemouth, UK. Kelly, C. A., Ayoko, G. A. and Brown, R. J. (2004), Can Environmentally Adapted Lubricants Reduce Two-Stroke Outboard Engine Emissions?, Journal of Environmental Science and Technology, USA. (Submitted) Kelly, C.A., Ayoko, G.A., Brown, R.J., 2004. Comparison of lubricant type and engine configuration as factors contributing to emissions to water from outboard motors. Invitation for submission of paper to special issue of Journal of Materials and Design. Invitation accepted 5th February, 2004.


xvi

Acknowledgements

This thesis, while an original work by the author, would not have been possible

without the assistance of many people. I would first like to thank all the technical

staff members of the School of Mechanical, Manufacturing and Medical Engineering

here at QUT who contributed to varying degrees to the eventual completion of the

research. In particular, the assistance of Mr Anthony Loberto, Mr Glen Turner, Mr

Bob May, Mr David McIntosh and Mr Mark Hayne was greatly valued and

appreciated. A special thanks also needs to be extended to Ass Prof Doug

Hargreaves and Adj Prof Will Scott whose academic and professional guidance was

invaluable.

I would also like to acknowledge the contribution of Mercury Marine who kindly

donated an outboard engine and a test tank for the research. Likewise, Honda

Marine also donated an outboard engine and their contribution is also greatly

appreciated. Another special thanks is extended to Fuchs Lubricants Australia for

their kind support. If not for their generosity the project would not have existed.

To my associate supervisor Dr Godwin Ayoko, I express my great appreciation for

his support and patience during the process of learning how to use his equipment,

and for the time spent in discussion on the statistical matters of the project. I also

extend my great appreciation to my principal supervisor Dr Richard Brown for his

support and guidance and his ability to always get the best out of myself and the

project. Without his patience and dedication to the project this research would not

have been possible.


xvii

A final thankyou to my wife Melissa, daughter Laura, and son Shaun. If not for the

love and support you have shown over the years, I doubt that this would have been

possible. You have, and always will, provide me with a constant source of

inspiration, and no words of gratitude could ever truly express what your support has

meant to me. I love you.


xviii

Signed Statement

I hereby certify that the work embodied in this thesis is the result of original research

and has not been submitted for a higher degree to any other University or Institution.

To the best of my knowledge and belief, the thesis contains no material previously

published or written by another person except where due reference is made in the

thesis itself.

_______________________________ Charles Kelly B Eng (Hons)


Chapter 1 - Introduction 1

CCHHAAPPTTEERR 11

Introduction

1.1 Background

There has been a vast amount of research that has led the USEPA to enforce strict

emission restrictions on two-stroke engines. It is now mandated that these types of

engines must reduce their emissions of hydrocarbons and NOx by 75% by the year

2006 (McFall, 2002). This has lead engine manufacturers to make design changes

such as direct fuel injected two-stroke engines, or shift to the manufacture of four-

stroke engines.

Two-stroke engines have many advantages over four-stroke engines of a similar

power; including, their simplicity and economy of manufacture, and much better

power to weight ratio. They are used in a wide range of applications including, but

not limited to; cars, motorcycles, lawn care equipment, chainsaws and recreational

boat engines. Their disadvantages include; noise, and use of a total loss lubrication

system.

Total-loss lubricants are lubricants that are lost directly to the environment during

normal use, such as; chainsaw bar and chain oil, railroad flange oils and greases, drip

oils, wire rope lubricants, dust suppressants, marine lubricants, and two-stroke

engine oils (Nelson, 2000a). Among this group of lubricants, two-stroke engine oils

are unique in that they undergo a process of combustion within the cylinder of an

engine.



Research has found that millions of litres of unburned fuel and oil are released into

marine environments each year from conventional marine two-stroke engines

(Martin, 1999). Other comparative studies between different types of two-stroke

engines and four stroke engines have found that carburetted two-stroke engines emit

particulate matter at rates approximately 4.5 times the rate of a fuel injected two-

stroke engine and 20-80 times the rate of a four-stroke engine (Kado et al., 2000).

A study of two-stroke lawn mowers in Newcastle, Australia, found that on average,

34% of the fuel/oil mixture short-circuited directly into the exhaust. The study also

estimated that in comparison to local transport sources, this type of lawn mower

contributes 5.2% of CO and 11.6% of NMHC emissions in the area (Priest et al.,

2000).

Other research has shown that, in one day’s use, a single two-stroke powered

personal water craft (Jet Ski) will emit the same amount of hydrocarbons and

nitrogen oxides to the atmosphere as a 1998 model family sedan that travels 160,000

km (Martin, 1999). Other studies have shown the hydrocarbon emissions from these

engines to not only be detrimental to water quality, but also to marine biota (Juttner

et al., 1995b, Juttner et al., 1995a, Rye et al., 2000, Tjarnlund et al., 1996, Tjarnlund

et al., 1995, USEPA, 1974, Warrington, 1999).

With the focus now on the replacement of these engines with alternatives that have

significantly reduced emission rates of pollutants, the engines that already exist are

being neglected. A typical two-stroke engine can expect to have a life span of

anywhere between ten and twenty years; so what of the pollutants that will still be



emitted? The studies outlined above show that there is a need for immediate

solutions as well as the longer-term measures already adopted.

As previously mentioned, total loss lubricants have been an environmental concern

for some time, and will be for some time to come. The challenge then is to reduce

the impacts of these lubricants. In the early 1980’s European lubricant

manufacturers went about developing Environmentally Adapted Lubricants (EALs)

in an effort to reduce the potential impacts of their products. Their development was

in response to early environmental mandates implemented by certain European

countries. They are derived from vegetable oils; with the most common being

canola, soy and sunflower, and they have been shown to be low in toxicity and

rapidly biodegradable. Canola is a crop that is widely cultivated in Europe, and it is

now the primary type of vegetable oil used for lubricants in the European market. In

particular, Germany and the Alpine region countries have spent years of research in

developing the performance characteristics of canola oil (Nelson, 2000a).

Past research reports that two-stroke outboard engines were the first application of

EALs, and they were an ester-based fluid with suitable ash less detergent additives

and low aromatic solvents. Initial tests have shown these products to have excellent

high dilution and low pollution characteristics (van der Waal et al., 1993). Viewed

from the concept of ecologically sustainable development (ESD), these products

have far reaching advantages over the development of mineral based products

because they are derived from renewable resources.



This study has investigated the pollutants that remain within the water column after

combustion, in view of the fact that most two-stroke outboard engines emit their

gases below the water line. Also, a comparison of the emissions when using an EAL

and an equivalent mineral oil has been conducted to investigate the difference (if

any) in the amounts and diversity of pollutants emitted by an engine using these

different types of oils. Since two-stroke engines emit a considerable part of their

fuel/oil mixture into the water, and it has been documented that the toxicity of these

emissions can persist for up to 14 days in water (Juttner et al., 1995b), it is

reasonable to expect that the EAL would minimise the adverse effects of such

emissions on aquatic ecosystems. Further, the use of an EAL could reduce the

emission of hydrocarbons from two-stroke engines. Another comparison of the

emissions was conducted between a two-stroke engine and a four-stroke engine.

While past research has noted the substantial difference in the emission rates

between the two types of engine, this is the first study to compare the emissions that

remain within the water column. The comparative tests for the two-stroke engine

were conducted both in the laboratory and in the field. The comparative tests for the

four-stroke engine were conducted in the laboratory and were compared to the two-

stroke engine laboratory tests.

1.2 Aims and Objectives of the Project

• To investigate the underwater emissions from outboard engines, which:

Requires identification of the pollutants, and

Quantification of the pollutants

• To compare the above from a two-stroke engine when using a mineral oil and an

equivalent environmentally adapted lubricant



• To compare the emissions to both fresh and sea water when using both lubricants

and the two-stroke engine

• To compare the emissions from both two and four stroke engines

• To estimate the concentrations of the pollutants at various distances in the wake

behind the boat using a simple dispersion model

• To determine the toxicity of the aforementioned at those distances by using

Toxicity Equivalence Factors


Chapter 2 – Literature Review 6

CCHHAAPPTTEERR 22

Literature Review

2.1 Background

The World’s Oceans are a chemical system covering 71% of the Earth’s surface, and

account for 77% of the water in the hydro – geological cycle. Seawater is a solution

of gas and solids containing both organic and inorganic compounds. It is considered

as a sink for all the salts that are present in sediments from the weathering process of

the lithosphere (Yen, 1999).

Hydrocarbon (oil) contamination poses serious threats to the marine environment.

This was recognised by the British Government as early as 1922, when a law was

passed prohibiting the discharge of oil or oily waste in territorial waters. In 1975, the

U.S. National Academy of Science workshop estimated that approximately 6 million

tons of petroleum hydrocarbons entered the oceans yearly; 40% of which was from

normal vessel operations (Yen, 1999).

Queensland Transport: Marine Pollution Section, (1989), suggested that 3.2 million

metric tonnes of oil finds its way into the world’s oceans each year, with 33% being

from normal vessel operations and a further 12% from tanker accidents.

In 1973, Australia developed a National Plan to Combat Pollution of the Sea by Oil

and Other Noxious and Hazardous Substances. The objectives, today, of the

National Plan are based on Australia’s obligation as a signatory to the International



Convention on Oil Pollution Preparedness, Response and Co-operation 1990.

Equally as important, the Plan aims to protect both natural and artificial (man made)

environments from the adverse effects of oil pollution and minimise those effects

where protection is not possible (Nelson, 2000b).

Nelson, (2000b), reported further that in 1998 the Plan was extended to cover

chemical spills. Despite this, the Plan exists to combat spills of oil and chemicals

from tankers; it makes no recognition of the contribution of normal vessel operations.

Yet, as can be seen above, figures suggest that these contributions can far exceed

those of tanker spills. Normal vessel operations is a broad term that encompasses a

wide range of operations, including but not limited to:

• Tanker operations

• Tourist vessel operations

• Public transport vessels such as ferries

• Fishing fleets

• Naval and coast guard operations, and

• Recreational vessels

For the most part, the maritime industry is well regulated in Australia with legislation

in place to control discharges from all government, tourist and other licensed

professional operators. A significant area of concern however, is the emissions from

recreational vessels. Within Queensland alone there are 155,000 registered

recreational vessels (Queensland Department of Transport, 2001), the emissions from

which are largely unregulated. It should also be noted that in Queensland it is not a

requirement to register a vessel that has an outboard engine smaller than four-horse



power, and that the vast majority of registered vessels are powered by two-stroke

engines.

Studies have shown that, in one day’s use, a single two-stroke powered personal

water craft (jet ski) will emit the same amount of hydrocarbons and nitrogen oxides

to the atmosphere as a 1998 model family sedan that travels 160,000 km (Martin,

1999). Other studies overseas (discussed in more detail later) have shown the

hydrocarbon emissions from two-stroke engines to not only be detrimental to water

quality, but also to marine biota (USEPA, 1974, Warrington, 1999, Tjarnlund et al.,

1995, Tjarnlund et al., 1996, Rye et al., 2000, Juttner et al., 1995a, Juttner et al.,

1995b).

In recognition of these facts, FUCHS PETROLUB AG has developed the FUCHS

PLANTO product range of environmentally friendly and rapidly biodegradable

lubricants. Furthermore, the company has initiated The FUCHS Great Barrier Reef

Millennium Project, in which the primary objective is to preserve the ecosystem of

the World Heritage Listed Great Barrier Reef area. The Australian Institute of

Marine Science (AIMS) has been charged with the task of investigating the impacts

of these rapidly biodegradable lubricants on the sensitive marine ecosystem.

AIMS conducts scientific research in all tropical Australian seas and coastal regions,

and provides information and technology for its clients. It is an independent

institution whose objectives are to promote the conservation and sustainable

development of Australia’s marine resources. Fields of study such as Tribology,

Mechanical Engineering, and Dispersion Modelling do not fall within the functions



of AIMS. Therefore, FUCHS Australia Pty Ltd are sponsoring a post graduate

student at QUT (in the form of a SPIRT Grant) to conduct these necessary

components of the research.

2.2 The Two-Stroke Engine

The internal combustion engine is currently the most widely used mechanical power-

producing device; there are two main types: the two-cycle (stroke) motor and the

four-cycle (stroke) motor. The main difference between the two types of engine is

the gas exchange process – how much fuel is being transferred. This also affects the

amount of power the engine can produce (Marshall, 2001).

The basic engine operation of a two-stroke engine consists of only two movements -

the compression stroke and the combustion stroke; hence the term two-stroke motor.

Conversely, a four-stroke engine consists of the intake, compression, combustion and

exhaust strokes (Marshall, 2001).

More specifically, two-stroke engines were named as such, because they only require

two strokes of the cylinder (or one crankshaft revolution) to complete the

thermodynamic cycle - the Otto Cycle. The ‘Otto’ or spark-ignition thermodynamic

cycle consists of the induction, compression, expansion (power) and exhaust actions

(in that order). To complete this cycle in two cylinder strokes instead of four, the

engine has to execute the induction and compression processes in one stroke and the

expansion and exhaust processes in the other (Marshall, 2001).

2.2.1 How a Two-Stroke Engine Works

Following is a more detailed description of the two-stroke engine cycle.



At the start of the cycle, a mixture of fuel and air is first compressed in the cylinder.

The moment the spark plug fires, the mixture will ignite. The resulting explosion

(and pressure) will then drive the piston downwards. This downward force will

compress another fuel/ air mixture in the crankcase. When the piston starts to

‘bottoms out’ (at the end of the downward cycle), the exhaust port is uncovered. The

pressure in the cylinder will then drive out the combusted gases from the cylinder

(Marshall, 2001).

At about the same time, the intake port is uncovered. The piston’s downward

movement pressurises the mixture in the crankcase, while moving from a region of

high pressure to an area of lower pressure. This principle ensures that a new mixture

of fuel and air rushes in to take the place left void by the exhaust, repeating the above

cycle (Marshall, 2001).

2.2.2 Advantages and Disadvantages of Two-Stroke Engines

The advantages (as compared to four-stroke engines) of two-stroke engines include:

• Low cost

• Design suitable for rugged operation

• More reliable operating behaviour

• Higher power output (for given equivalent size and weight of motor)

• Higher operational efficiency

• Low amounts of NOx (oxides of nitrogen) emissions in exhaust

Some disadvantages of these motors include:

• Two-stroke motors do not last as long as their four-stroke counterparts. The main

reason is that two-stroke engines lack a dedicated lubrication system

• Two-stroke oils are more costly to produce and procure



• Poor fuel efficiency (up to 30% of the fuel/oil mixture is exhausted either

unburned or partially burned into aquatic environments)

2.3 Tribology

An integral part of engineering is a consideration of what happens at the interface

between touching components. When the surface of one component moves over

another, there is always a resisting frictional force. If the surfaces are in close

proximity then peaks of the surface roughness (called asperities) interact, increasing

friction, and may cause surface damage. The primary purpose of a lubricant is to

separate these contacting surfaces and thereby reduce friction and wear. The science

involved in the study of such processes is Tribology. It encompasses the study of

friction, wear, lubrication and contact mechanics (Lewis, 2001).

Within an engine, lubrication is required to reduce friction thereby minimising the

wear between the moving parts. It also cools the engine, allowing it to operate at

safe temperatures. Typically, a four-stroke engine has a lubricating system that is

separate from its fuel system, whereas, a two-stroke engine often has oil mixed with

its fuel so that the cylinder walls and the crankcase bearings are adequately

lubricated.

Comparative exhaust emission tests between two and four-stroke engines have

consistently shown that the two-stroke version can emit up to seven times the level of

toxic pollutants for engines of the same power output (Juttner et al., 1995b, Juttner et

al., 1995a, Kado et al., 2000, Mace, 2000, Priest et al., 2000). In addition, even

though they have small two-stroke engines, results show that scooters emit

equivalent amounts of pollutants to that of cars, trucks and buses due to incomplete



combustion of the fuel/lubricant mixture. The scooter exhaust particulate matter

(comprising mainly of polycyclic aromatic hydrocarbons) is highly mutagenic, which

is shown to be significantly dependent on the type of lubricant used in the engine

(Zhou et al., 1998), therefore, a review of the fuel/lubricant mixture is undertaken.

2.3.1 General Characteristics of Petroleum

Crude petroleum and most refined petroleum products are complex mixtures of many

thousands of organic compounds, with hydrocarbons usually representing more than

75 per cent of the weight of the oil. The remainder is made up of various nitrogen,

oxygen, and sulphur containing organic compounds, and some metals (Neff, 1979).

Nearly all petroleum compounds are non-polar and not very soluble in water. The

behaviour of these compounds in the environment depends on the physical and

chemical nature of the particular hydrocarbon, and these properties change as the

petroleum ages and weathers (Weiner, 2000).

2.3.2 Types of Petroleum Products

Crude oil is refined into petroleum products through a process known as fractional

distillation. Fractional distillation is a process that separates the oil components

according their boiling points. Each fraction represents a group of mixtures, which

have boiling points within a specific range (Weiner, 2000). Table 1 describes the

principal petroleum fractions that are produced by the fractional distillation process.



Table 1: Principal Petroleum Fractions from Fractional Distillation

Source: Table 5.1: Principal Petroleum Fractions from Fractional Distillation (Weiner 2000)

a The notation used gives the number range of carbon atoms in the fractional compounds; e.g. C1 – C4

means hydrocarbon compounds containing between 1 and 4 carbon atoms.

2.3.3 Gasolines and Lubricating Oils

Of particular interest in this study are gasolines and lubricating oils. Consisting

mainly of aliphatic and aromatic hydrocarbons, gasolines are among the lightest

liquid fractions of petroleum (C4 – C12) (Weiner, 2000).

Weiner, (2000), reports that Aliphatic Hydrocarbons consist of:

• Alkanes, which are saturated hydrocarbons (all carbons are connected by single

bonds)

• Alkenes, which are unsaturated hydrocarbons having one or more double bonded

carbon atoms, and

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This table is not available online. Please consult the hardcopy thesis available from the QUT Library



• Alkynes, which are unsaturated hydrocarbons having one or more triple bonded

carbon atoms.

Aromatic hydrocarbons are hydrocarbons based on the benzene ring as a structural

unit. They include monocyclic hydrocarbons such as benzene, toluene, ethyl

benzene, and xylene (the BTEX group), and polycyclic hydrocarbons such as

naphthalene and anthracene (Weiner, 2000). More generally, Weiner, (2000),

suggested that gasoline mixtures are volatile and somewhat soluble. They contain a

much higher percentage of the BTEX group of aromatic hydrocarbons than do other

fuels, such as diesel. Furthermore, they contain lower concentrations of heavier

aromatics like naphthalene and anthracene than do diesel and heating fuels. For this

reason, the presence of BTEX is often a useful indicator of gasoline contamination.

(Weiner, 2000), identified lubricating oils as being composed of heavier molecular

weight compounds, encompassing the approximate range of C15 – C40. They are

more viscous and less soluble in water.

2.3.4 The General Fate of Hydrocarbons in the Marine Environment

When hydrocarbons are released into the marine environment, they spread on the

surface of the water. At the same time, components of low boiling point evaporate

rapidly, entraining successively higher boiling point fractions. Significant amounts

of compounds up to C8 are carried off this way.

Even so, the entry of petroleum hydrocarbons into the aquatic food web has been

clearly demonstrated. The vulnerability of the marine environment to petroleum has

been revealed time and again by oil spills, where certain petroleum hydrocarbons



have been shown to interfere with chemoreceptive and reproductive processes (Yen,

1999). Martin, (1999), reported that scientists have determined that millions of litres

of unburned fuel and oil are released into marine environments each year from two-

stroke engines. This is because these engines discharge as much as 30% of their

fuel/oil mixture directly into the water within their exhaust stream.

2.3.5 The Fuel/Oil Mixture as a Pollutant

Of particular interest in this study are, the products of combustion emitted as exhaust

from outboard engines and those products that are emitted as unburned components.

The preliminary study conducted early in the project identified the presence of

polycyclic aromatic hydrocarbons, (PAHs), and volatile organic compounds,

(VOCs), remaining in the water column after the engine had been used; these are

discussed in more detail (Kelly et al., 2001a, Kelly et al., 2001b).

2.3.5.1 Polycyclic Aromatic Hydrocarbons

As previously noted, hydrocarbons that display benzene-like properties are called

aromatic; those that contain fused benzene rings are called polynuclear or Polycyclic

Aromatic Hydrocarbons, (PAHs). PAHs are formed when carbon-containing

materials are incompletely burned (Baird, 1999). The simplest PAH example is

naphthalene, C10H8; Figure 1 shows a diagrammatical representation of this

molecule.

or

Figure 1: Diagrammatical Representation of the Naphthalene Molecule

C C

C C

C

C

C

C

C

C

H

H H

H

H H

H

H



There are two ways an additional benzene ring can be fused to the two of the

naphthalene molecule; one results in a linear arrangement for the centres of the rings,

while the other is a branched arrangement, these are displayed in Figure 2. The

linear arrangement is known as anthracene and the branched (or angular)

arrangement, phenanthrene (Baird, 1999).

Figure 2: Diagrammatical Representation of the Anthracene and Phenanthrene Molecules

Neff, (1979), reported that there are two molecular weight classes of PAHs, and that

they are distinguished on the basis of their physical, chemical, and biological

properties. These are the lower molecular weight 2 – 3 ring aromatics as shown

above, and the higher molecular weight 4 – 7 ring aromatics, an example of which is

shown in Figure 3.

Pyrene Benzo(a)pyrene

Figure 3: Diagram of the Heavier PAH Molecules Pyrene and Benzo(a)pyrene

The low molecular weight PAHs have been shown to display acute toxicity to

aquatic organisms, whereas the high molecular weight PAHs do not. However, all of

the 20 – 30 proven PAH carcinogens are in the high molecular weight category

Anthracene

Phenanthrene



(Neff, 1979). Table 2 shows the carcinogenic potential of the sixteen USEPA

priority PAH pollutants.

Table 2: Carcinogenic Potential of the Sixteen USEPA Priority PAH Pollutants

Source: (Manoli et al., 1999) Blank – not tested for human carcinogenicity 2A – Probably carcinogenic to humans 2B – Possibly carcinogenic to humans 3 – Not classifiable as to human carcinogenicity

Baird, (1999), reported that the mechanism of PAH formation during combustion is

complex and difficult to fully ascertain. Neff, (1979), suggested that part of the

reason for this is that petroleum products from different sources vary tremendously

in the relative concentrations of the different hydrocarbon types present. It is thought

however, that PAHs are produced by the re-polymerisation of hydrocarbon fragments

that are formed during the cracking, that is, the splitting into several parts, of larger

fuel molecules in the flame. The re-polymerisation reaction is thought to occur more

readily under oxygen-deficient conditions, and therefore the rate of PAH formation

will increase as the air:fuel ratio decreases.

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PAHs are serious water pollutants (Baird, 1999). However, if the total estimated

amounts of PAHs that enter the aquatic environment were evenly distributed

throughout the world’s oceans and freshwater bodies, their concentrations would be

completely undetectable. Yet, they are not evenly distributed. Most PAHs remain

relatively near their point source, and can be expected to decrease in concentration

approximately logarithmically with distance from the source. Thus, the majority of

PAHs entering the aquatic environment are localised in rivers, estuaries, and coastal

marine waters (Neff, 1979).

In the past, marine pollution by PAHs has been attributed to sources such as

creosote-treated timber from docks. This source was so serious in parts of Atlantic

Canada in the early 1980’s that the local lobster fisheries industry was closed down

because of the high PAH levels found in the crustaceans. Larger PAH molecules are

thought to have played a role in the devastation of the populations of beluga whales

in the St. Lawrence River, and they have also been linked to the production of liver

lesions and tumours in some fish (Baird, 1999).

The United States Environmental Protection Agency (USEPA), and The Australian

and New Zealand Environment and Conservation Council (ANZECC) have

recognised the potential toxic threat of PAHs within the marine environment. The

USEPA has identified one hundred and twenty six priority pollutants within its

Water Quality Standards, sixteen of them PAHs. ANZECC has assigned trigger

levels within their Water Quality Guidelines for a number of these PAH pollutants

(USEPA, 1988, ANZECC, 2000); these are outlined in Table 3.



Table 3: USEPA PAH Priority Pollutants and their Australian Water Quality Guideline Trigger Levels

* = Level of protection, i.e., for naphthalene (marine water) 50μg/L to protect 99% of species and 120μg/L to protect

80% of species.

A = Chemicals for which possible bioaccumulation and secondary poisoning effects should be considered.

Insufficient data to derive a reliable trigger value.

a = Low reliability trigger levels should only be used as an indicative interim working level until more reliable acute

and chronic toxicity data allow for the calculation of reliable guideline values (as for naphthalene).

The presence of some or all of these sixteen pollutants is taken to imply that there are

actually many other pollutants present in the source. These pollutants form an

aggregate substance group for which data is available. A summary of each of these

sixteen compounds now follows.

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Naphthalene

Naphthalene is composed of two fused benzene rings with the empirical formula of

C10H8. It has a molecular weight of 128.19, a melting point of 80.5°C, a boiling

point of 218°C, and a vapour pressure of 0.0109kPa at 25°C. Naphthalene is almost

insoluble in water, but is soluble in benzene, toluene, ether, and several other organic

solvents. Naphthalene is used as raw material in the chemical, plastics, and dye

industries, and as an intermediate for the manufacture of synthetic resins, celluloid,

solvents, and lubricants (Faust, 1993b).

Acenaphthene

Acenaphthene is a tricyclic aromatic hydrocarbon with a chemical formula of C12H10

and a molecular weight of 154.21. It is a crystalline solid with a boiling point of

279°C, a melting point of 95°C, a density of 1.189 g/mL, and a vapour pressure of 6

x10-4 kPa. Acenaphthene is insoluble in water but is soluble in ethanol, methanol,

propanol, chloroform, benzene, and toluene. Acenaphthene occurs in coal tar

produced during the high temperature carbonization or coking of coal, and is used as

a dye intermediate, in the manufacture of some plastics. It is also used as an

intermediate in the manufacture of insecticides and fungicides (Faust, 1994a).

Anthracene

Anthracene is the simplest tricyclic aromatic hydrocarbon and has a chemical

formula of C14H10 and molecular weight of 178. It has a melting point of 216°C, and

a boiling point of 340°C. Anthracene is soluble in a variety of organic solvents,

including ethanol, methanol, benzene, toluene, and carbon disulfide, but is almost

insoluble in water. It is derived from coal tar and is primarily used as an



intermediate in the production of dyes, but it has also been used in the production of

smoke screens, scintillation counter crystals, and organic semiconductor research

(Faust, 1991).

Acenaphthylene

Acenaphthylene is a low molecular weight, 2-ring (C12H8) PAH. Acute toxicity is

rarely reported in humans, fish, or wildlife, as a result of exposure to low levels of

this compound. Acenaphthylene is a component of crude oil, coal tar and a product

of combustion that may be produced and released to the environment during natural

fires. Emissions from petroleum refining and coal tar distillation are major

contributors of acenaphthylene to the environment. Acenaphthylene is contained in a

variety of coal tar products and may be released to the environment via

manufacturing effluents and the disposal of manufacturing waste by-products.

Because of the widespread use of materials containing acenaphthylene, releases to

the environment also occurs through municipal wastewater treatment facilities and

municipal waste incinerators (Irwin, 1997a).

Benz(a)anthracene

Benz(a)anthracene contains four aromatic rings two of which share carbons with

only one other ring. It is soluble in alcohol, ether and benzene but practically

insoluble in water. There is no commercial application for benz(a)anthracene,

however, it is a ubiquitous contaminant formed during the incomplete combustion of

organic material. Benz(a)anthracene is found in various kinds of smoke and flue

gases, tobacco smoke, tobacco smoke condensate, automobile exhaust, roasted coffee

and in charcoal broiled, barbecued or smoked meats. It is also found in creosote,



coal tar, petroleum asphalt, and a variety of foods, including vegetable oils and

baker's yeast. It has an expected half-life that varies from less than 1 day to several

weeks dependent on the nature of the particulate matter to which it is adsorbed. It

has been found to persist in soil from days to years depending on the adsorbent and

the micro-organisms present (Francis, 1992).

Chrysene

Chrysene has the empirical formula of C18H12. It has a molecular weight of 228.30, a

melting point of 256 °C, and a boiling point of 448°C. Chrysene has been shown to

be very toxic to aquatic organisms, and therefore may cause long-term adverse

effects in the aquatic environment. Chrysene's release to the environment is quite

wide spread since it is a ubiquitous product of incomplete combustion. It is largely

associated with particulate matter, soils, and sediments. If released to water, it will

adsorb very strongly to sediments and particulate matter, but will not hydrolyse or

appreciably evaporate. Chrysene will bioconcentrate in species that lack microsomal

oxidase. Especially high exposure will occur through the smoking of cigarettes and

ingestion of certain foods (smoked and charcoal broiled meats and fish) (Irwin,

1997b).

Benzo(a)pyrene

Benzo(a)pyrene, also known as BaP, has the chemical formula of C20H12 and a

molecular weight of 252.3. It exists as yellowish plates and needles, has a boiling

point of 310-312ºC, a melting point of 178ºC, and a density of 1.35. Benzo(a)pyrene

is practically insoluble in water but is soluble in benzene, toluene, xylene and

sparingly soluble in alcohol and methanol. No current commercial production or use



of benzo(a)pyrene is known. It occurs ubiquitously in products of incomplete

combustion and in fossil fuels. It has been identified in surface water, tap water,

rainwater, groundwater, wastewater, and sewage sludge. The estimated half-lives for

benzo(a)pyrene are less than 1-8 hours in water, but 5-10 years in sediment

(Daugherty, 1992).

Benzo(b)fluoranthene

Benzo(b)fluoranthene is a polycyclic aromatic hydrocarbon (PAH) with one five-

membered ring and four six-membered rings. It is a crystalline solid with a chemical

formula of C20H12, a molecular weight of 252.32, and a melting point of 168ºC.

Benzo(b)fluoranthene is virtually insoluble in water and is slightly soluble in

benzene and acetone. There is no commercial production or known use of this

compound. Benzo(b)fluoranthene is found in fossil fuels and occurs ubiquitously in

products of incomplete combustion. It has been detected in mainstream cigarette

smoke; urban air; gasoline engine exhaust; emissions from burning coal and from

oil-fired heating; broiled and smoked food; oils and margarine; and in soils,

groundwater, and surface waters at hazardous waste sites (Faust, 1994b).

Benzo(ghi)perylene

Benzo(g,h,i)perylene, also known as 1,12-benzoperylene, is a polycyclic aromatic

hydrocarbon (PAH) with six aromatic rings. It is a crystalline solid with a chemical

formula of C22H12 and a molecular weight of 276.3, and a melting point of 278.3ºC.

Benzo(g,h,i)perylene is practically insoluble in water but is soluble in 1,4-dioxane,

dichloromethane, benzene, and acetone. There is no known commercial production

or use of benzo(g,h,i)perylene. It occurs naturally in crude oils and is present



ubiquitously in products of incomplete combustion and in coal tar. It has been

identified in cigarette smoke, charcoal-broiled steaks, and edible oils. It has also

been found in soils, groundwater, and surface waters at hazardous waste sites (Faust,

1994c).

Benzo(k)fluoranthene

Benzo(k)fluoranthene is a PAH with one five-membered and four six-membered

rings. It is a crystalline solid with a chemical formula of C20H12, a molecular weight

of 252.32, a melting point of 217ºC, and a boiling point of 480ºC.

Benzo(k)fluoranthene is insoluble in water but is soluble in acetic acid, benzene, and

ethanol. No commercial production or commercial use of benzo(k)fluoranthene is

known at this time; however small amounts of this compound are used for research.

Benzo(k)fluoranthene is found in fossil fuels and occurs ubiquitously in products of

incomplete combustion. It has been detected in mainstream cigarette smoke;

gasoline engine exhaust; emissions from burning coal and from oil-fired heating;

lubricating oils; used motor oils; and crude oils. It has also been found in soils,

surface waters, and groundwater at hazardous waste sites (Faust, 1994d).

Dibenz(ah)anthracene

Dibenz(a,h)anthracene, also referred to as 1,2,5,6-dibenz(a,h)anthracene, 1,2:4,6-

dibenz(a,h)anthracene, 1,2:5,6-dibenz(a,h)anthracene, DB(a,h)A, or DBA, is a

polycyclic aromatic hydrocarbon (PAH) with five aromatic rings. It has a molecular

formula of C22H14, a molecular weight of 278.33, and a melting point of 266ºC.

Dibenz(a,h)anthracene exists as crystalline plates or leaflets and is insoluble in water,

slightly soluble in alcohol and ether, and soluble in petroleum ether, benzene,



toluene, xylene, oils, and other organic solvents. No commercial production or use

of dibenz(a,h)anthracene is known. It occurs as a component of coal tars, shale oils,

and soots and has been detected in gasoline engine exhaust, coke oven emissions,

cigarette smoke, charcoal broiled meats, vegetation near heavily travelled roads, and

surface water and soils near hazardous waste sites (Faust, 1995).

Fluoranthene

Fluoranthene PAH with a chemical formula of C16H10 and a molecular weight of

202.26. It exists as pale yellow needles or plates, has a boiling point of 375ºC, a

melting point of 111ºC, and a density of 1.252 at 4ºC. Fluoranthene is almost

insoluble in water, but is soluble in alcohol, ether, benzene, and acetic acid.

Fluoranthene can be produced by the pyrolysis of organic raw materials such as coal

and petroleum at high temperatures; it is also known to occur naturally as a product

of plant biosynthesis. It is a constituent of coal tar and petroleum-derived asphalt,

however, currently, there is no known production or use of this compound.

Fluoranthene is a common environmental pollutant that has been found in products

of incomplete combustion of fossil fuels, main stream cigarette smoke, and in char-

broiled foods. It has been identified in surface, drinking, and wastewater, in lake

sediments, and in ambient air (Faust, 1993a).

Fluorene

Fluorene has the empirical formula of C13H10. It has a molecular weight of 166.22, a

melting point of 112°C, and a boiling point of 298°C. Acute toxicity is rarely

reported in humans, fish, or wildlife, as a result of exposure to low levels of a single

PAH compound such as this one. PAHs in general are more frequently associated



with chronic risks. These risks include cancer and often are the result of exposures

to complex mixtures of chronic-risk aromatics (such as PAHs, alkyl PAHs, benzenes,

and alkyl benzenes), rather than exposures to low levels of a single compound such

as this. As such, fluorene is not classified as a human carcinogen (Irwin, 1997c).

Indeno(123-cd)pyrene

Indeno(1,2,3-cd)pyrene, also known as IP, ortho-phenylenepyrene, 1,10 (ortho-

phenylene)pyrene, 1,10-(1,2-phenylene)pyrene, and 2,3-ortho-phenylenepyrene

(IARC, 1983), is a PAH with one five-membered ring and five six-membered rings.

It is a crystalline solid with a chemical formula of C22H12, a molecular weight of

276.3, a melting point of 163.6ºC, and a boiling point of 530ºC. Indeno(1,2,3-

cd)pyrene is insoluble in water but is soluble in organic solvents. There is no

commercial production or known use of indeno(1,2,3-cd)pyrene. The compound is

found in fossil fuels and occurs ubiquitously in products of incomplete combustion.

It has been detected in mainstream cigarette smoke; gasoline engine exhaust;

emissions from burning coal; lubricating oils; used motor oils; and soils, surface

waters, and groundwater at hazardous waste sites (Faust, 1994e).

Phenanthrene

Phenanthrene is a PAH with three aromatic rings. It has a chemical formula of

C14H10, a molecular weight of 178.22, and exists as a colourless crystalline solid. It

has a melting point of 100ºC, a boiling point of 340ºC, and a density of 1.179 at

25ºC. Phenanthrene is almost insoluble in water, but is soluble in acetic acid and a

number of organic solvents including ethanol, benzene, carbon disulfide, carbon

tetrachloride, diethyl ether, and toluene. Phenanthrene can be produced by fractional



distillation of high-boiling coal tar oil. It can be used in the manufacture of

dyestuffs, explosives, drugs, in the synthesis of phenanthrene quinone, and in

biochemical research. A derivative, cyclopentenophenanthrene, has been used as a

starting material for synthesizing bile acids, cholesterol, and other steroids.

Phenanthrene occurs in fossil fuels and is present in products of incomplete

combustion. Some of the known sources of phenanthrene in the atmosphere are

vehicular emissions, coal and oil burning, wood combustion, coke plants, aluminium

plants, iron and steel works, foundries, municipal incinerators, synfuel plants, and oil

shale plants. It is widely distributed in the aquatic environment and has been

identified in surface water, tap water, wastewater, and dried lake sediments. It has

also been identified in seafood collected from contaminated waters and in smoked

and charcoal-broiled foods. Although a large body of literature exists on the toxicity

and carcinogenicity of other PAHs, primarily benzo(a)pyrene, toxicity data for

phenanthrene are limited (Faust, 1993c).

Pyrene

Pyrene, also known as β-pyrene, is a PAH with four aromatic rings. It has a

chemical formula of C16H10 and a molecular weight of 202.26. Pure pyrene is a

colourless crystalline solid at ambient temperature; the presence of tetracene, a

common contaminant, gives it a yellow colour. Pyrene has a melting point of 156ºC,

a boiling point of 404ºC, and a density of 1.271 at 23ºC. It is almost insoluble in

water, but is soluble in benzene, carbon disulfide, diethyl ether, ethanol, petroleum

ether, toluene, and acetone. Pyrene can be derived from coal tar, but there is no

commercial production or known commercial use of this compound. Pyrene from



coal tar has been used as the starting material for the synthesis of benzo[a]pyrene

(Faust, 1993d).

2.3.5.2 Volatile Organic Compounds

A further pollution concern from the fuel/oil mixture is that of Volatile Organic

Compounds (VOCs) (Kelly et al., 2001a, Kelly et al., 2001b). Benzene, toluene,

ethylbenzene and xylenes are the simplest of the aromatic hydrocarbons group. They

are important and common aromatic solvents used for adhesives, resins, pesticides,

ink, and in the rubber industry. Benzene and toluene are used as fuel additives, and

xylenes are used in aviation fuel and in polymer manufacture. Ethylbenzene is a

constituent of crude oil, and these compounds together, referred to as the BTEX

group, are products of oil refining (ANZECC, 2000).

It has been stated above that two-stroke outboard engines are notorious for emitting

significant amounts of unburned hydrocarbons into the environment. Baird, (1999),

identified these liquid fuels, which readily vaporise, as VOCs, and further, that they

are a significant contributor to the problem of photochemical smog production.

ANZECC, (2000), suggest that the high volatility and relatively low water solubility

of these compounds indicates that they would be rapidly lost to the atmosphere from

a water body; with half-lives for evaporation of less than 5 hours at 20ºC. ANZECC,

(2000), also suggested that benzene and toluene are not expected to adsorb strongly

to sediments, biodegradation is very rapid, and the BTEX group of compounds do

not bio-accumulate. They acknowledge however, that their toxic effects are additive.

Table 4 shows the ANZECC guideline trigger levels for a number of the VOCs that

have been identified within our study.



Table 4: The Range of VOC Pollutants Identified and their Australian Water Quality Guidelines Trigger Levels

VOC Pollutants Australian Water Quality

Guidelines Trigger Level (μg/L)

Australian Water Quality Guidelines Low Reliability a

Trigger Level

(μg/L)

Compound Fresh Water Marine Water Fresh Water Marine Water

Benzene 600 – 2000* 500 – 1300*

Toluene A A 180 180

Ethyl benzene A A 80 5

o, m-xylenes 200 – 640* A 350

p-xylene 140 – 340* A 200

Trimethyl benzenes - - - -

Tetramethyl

benzenes - -

- -

Naphthalene Not considered

in terms of a

VOC

Not considered

in terms of a

VOC

Alkyl naphthalenes - - - -

* = Level of protection, i.e., for benzene (fresh water) 600μg/L to protect 99% of species and 2000μg/L to protect

80% of species.

A = Chemicals for which possible bioaccumulation and secondary poisoning effects should be considered.

Insufficient data to derive a reliable trigger value.

a = Low reliability trigger levels should only be used as an indicative interim working level until more reliable acute

and chronic toxicity data allow for the calculation of reliable guideline values (as for naphthalene).

A summary of the BTEX group of VOC compounds now follows.

Benzene

Benzene has a chemical formula of C6H6, and is a volatile a colourless liquid with a

characteristic "aromatic" odour. It has a molecular weight of 78.12 and a density of

0.87865 g/mL at 20°C. Benzene is used primarily in the production of other

chemicals such as ethylbenzene, cumene, and cyclohexane, and it is also used as a

solvent; although this use is declining. Benzene is emitted into the workplace and



the environment (aquatic, terrestrial, and atmospheric) from industrial and other

manmade sources, including gasoline from fuel stations, smoking tobacco products,

and auto exhaust (Daugherty, 1992).

Toluene

Toluene has a chemical formula of C6H5CH3 and a molecular weight of 92.15. It is

also known as methylbenzene and phenylmethane; it is a colourless liquid with a

sweet pungent odour. Toluene is isolated by distillation of reformed or pyrolised

petroleum and coal tar; however, most of the toluene produced remains as a benzene-

toluene-xylene (BTX) mixture for use in gasoline. The primary use of isolated

toluene is in the production of benzene and for back blending into gasoline to

increase octane ratings. Toluene is also used as raw material in the production of

benzyl chloride, benzoic acid, phenol, cresols, vinyl toluene, TNT, and toluene

diisocyanate; as a solvent for paints and coatings; and in adhesives, inks, and

pharmaceuticals (Faust, 1994f).

Ethylbenzene

Ethylbenzene is a colourless, flammable liquid with a pungent odour. It is

commonly used as a solvent, chemical intermediate in the manufacture of styrene

and synthetic rubber and as an additive in some automotive and aviation fuels.

Occupational exposure to ethylbenzene may occur during production and conversion

to polystyrene and during production and use of mixed xylenes. The general public

can be exposed to ethylbenzene in ambient air as a result of releases from vehicle

exhaust and cigarette smoke (Opresko, 1991).



Xylenes

Xylenes (dimethylbenzenes) are volatile solvents widely used in chemical synthesis,

consumer products, and agricultural chemicals. The chemical has a molecular

weight of 106.16, and a boiling point of 137°C, and is practically insoluble in water.

Xylenes occur naturally in petroleum and coal tar and are formed during bush fires;

chemical industries produce xylenes from petroleum. The commercial technical

product "mixed xylenes" generally contains about 40% m-xylene and 20% each of o-

xylene, p-xylene, and ethylbenzene, as well as small quantities of toluene. In this

summary, xylene or xylenes, refers to mixed xylenes unless the individual isomer is

specified. Because of its volatility, most of the xylene released to the environment

will enter the atmosphere where it undergoes photodegradation. Xylenes have been

measured in the air and drinking water of industrialised cities (Forsyth, 1994).

2.3.6 Environmentally Adapted Lubricants

Environmentally Adapted Lubricants are plant-based lubricants that are derived from

a range of vegetable oils. They are inherently biodegradable and low in toxicity

(Nelson, 2000a). For thousands of years, vegetable-based oils and animal fats served

as lubricants for machine parts. The rise of petroleum in the early 1900s, low crude

oil prices, and extensive transportation infrastructure, gave economic and

manufacturing advantages to petroleum-based lubricants (Nelson, 2000a).

Nelson, (2000a), noted however, that the current trend is shifting. The detrimental

effects of petroleum-based products on environmental and human health have

become more obvious. In response to this, high-performance vegetable oil-based

engine lubricants are currently being developed and marketed.



In the early 1980’s European lubricant manufacturers went about developing new

rapidly biodegradable lubricants in an effort to reduce the potential impacts of their

products. van der Waal et al., (1993), reported that two-stroke outboard engines

were the first application of EALs, and these were an ester based fluid with suitable

ash less detergent additives and low aromatic solvents. Their development was in

response to early environmental mandates implemented by certain European

countries.

The new range of products is still derived from vegetable oils; with the most

common being canola, soy and sunflower oils. Canola is a crop that is widely

cultivated in Europe, and it is now the primary type of vegetable oil used for

lubricants in the European market. In particular, Germany and the Alpine region

countries have spent years of research in developing the performance characteristics

of canola oil (Nelson, 2000a).

Initial tests have shown these products to have excellent high dilution and low

pollution characteristics. Viewed from the concept of ecologically sustainable

development, these products have more far reaching advantages over the

development of mineral based products because they are derived from renewable

resources. The introduction of environmentally adapted lubricants has been a

significant step forward in the protection of the environment. While recognising this,

van der Waal et al., (1993), recommends that the ecotoxicological aspects of the

products should be equally as important.



Juttner et al., (1995a), also recognised this fact whilst conducting their research. As

a part of their research, they measured the emissions from a two-stroke outboard

engine while using a variety of lubricating oils: three of them rapidly biodegradable.

Their conclusions, that there was virtually no difference in either the types or levels

of emissions regardless of the type of oil used (Juttner et al., 1995a, Juttner et al.,

1995b), further highlights the need for ongoing development within this field.

FUCHS PETROLUB AG is continuing with this area of research by developing the

FUCHS PLANTO product range of environmentally friendly and rapidly

biodegradable lubricants. This line of product has been awarded the “Blue Angel”

environmental seal because of its biodegradability and its adherence to other

stringent ecological guidelines. This PhD project intends to further investigate the

environmental qualities of the product by investigating the combustion by-products

emitted into the water. FUCHS Australia Pty Ltd. is providing support for this

research and is endeavouring to improve their product range based on its findings.

2.4 Previous Studies Related to Marine Engine Testing

As stated earlier, in Queensland alone there are currently 155,000 registered

recreational vessels. Based on the assumption that outboard engines emit up to 30%

of their fuel/oil mixture unburnt, the number in use, and the typical period of use, it

has been estimated that approximately 4,500,000 litres of oil and engine pollutants

are released by boats and ships into the Queensland marine/aquatic environment each

year (Environment Australia, 1999, Queensland Department of Transport, 2001).

It is not surprising then to find that the study of the emissions from outboard engines

has been investigated in the past, to varying degrees, in Europe and the USA. Two-



stroke engines have also been studied to a lesser degree in Australia, however, not

marine engines: these studies are reviewed and discussed in more detail.

2.4.1 European Studies

At the University of Stockholm, ecotoxicological studies were undertaken to

investigate the effects of two-stroke engine exhaust on fish, while at the University

of Zurich, the quantification of gases and VOCs, and their impacts on water quality,

were studied using both two and four-stroke engines. Another study by the

University of Amsterdam conducted a three year investigation into the use of

biolubricants in inland and coastal water activities (Tjarnlund et al., 1995).

The University of Stockholm conducted tests using a 2.3 kW two-stroke outboard

engine at 75% of full load until a pre-determined volume of fuel was consumed. The

collected water samples were then diluted, to levels expected to be found in the

environment, and exposed to fish (Tjarnlund et al., 1995).

Results showed that the combustion by-products in the exhaust are toxic to fish in

their developmental stages, and that toxicological effects could be measured in the

genetic material of adult fish (Tjarnlund et al., 1995).

A further study by the same research group found, that if the fish’s food was polluted

with combustion by-products, the emissions could be passed through the food chain;

and that this in turn caused disruptions to both biological and physiological functions

of the fish (Tjarnlund et al., 1996).



At the University of Zurich in Switzerland, a group has researched the effects of

outboard engines on water quality. In particular, the emission of VOCs and 14

aromatic compounds into the water, and the emission of gases (HC, NOx, CO) into

the air were quantitatively determined. A number of different fuels and lubricants

were compared and the effect of a catalyst on the types and levels of emissions was

investigated (Juttner et al., 1995a).

The research involved the use of three outboard engines, a two-stroke and a four-

stroke engine both with the same power output of 7.3kW, and a 15kW two-stroke

engine to compare the results for a higher powered engine (Juttner et al., 1995a).

Results showed that the 7.3kW two-stroke engine emitted HCs at a rate one order of

magnitude higher than the four-stroke engine of equivalent power rating, although,

both two-stroke engines had quite low NOx emissions. The use of ethanol as a fuel

marginally reduced the HC emissions of all the engines, but did not affect the

production of CO and NOx. It was found that VOCs were emitted into the water at a

constant rate under constant load, and the two-stroke engines were found to emit

VOCs at a rate 100 times that of the four-stroke engine. It was also found that the

type of lubricant that was used made virtually no difference in either the types or

levels of gaseous emissions within the exhaust streams of any of the engines (Juttner

et al., 1995a).

The researchers limited the use of the catalyst to the 7.3kW two-stroke engine. The

results showed that the HC and VOC emissions were reduced to extremely low

levels, and the CO emissions were also lower, however, still higher than the four-



stroke engine (Juttner et al., 1995a). In a further study by the same group, it was

found that the VOCs are major contributors to acute toxicity. It was therefore

deduced that the emissions from two-stroke engines are much more toxic than those

of four-stroke engines, although, it was shown that the use of a catalyst could

significantly reduce the VOC levels, and thereby, the toxicity levels (Juttner et al.,

1995b).

Another significant finding was; the toxicity of water samples from the two-stroke

engine did not degrade within 14 days, however, samples from both the four-stroke

and the catalyst fitted two-stroke engines degraded to negligible levels within 14

days (Juttner et al., 1995b).

At the University of Amsterdam the Loss Lubrication in Inland and Coastal Water

Activities (LLINCWA) project was initiated to stimulate the awareness of the

existence of biolubricants. The research tested and demonstrated the performance of

these products on and around inland and coastal waters, and it was made indisputably

clear that biolubricants are available for the majority of applications (Broekhuizen et

al., 2003).

2.4.2 Studies in the USA

The University of California, in conjunction with the Californian Air Resources

Board, investigated the emission of particulate matter (PM) from outboard engines.

Their aims were to identify the PM-associated PAHs, and the genotoxic affect of

these compounds (Kado et al., 2000).



The group tested three new outboard engines, a fuel injected two-stroke, a

carburetted two-stroke and a carburetted four-stroke each of 67kW.

Results showed that the carburetted two-stroke engine emitted the highest levels of

PM over the test cycle; approximately 4.5 times the PM emission levels of the fuel

injected two-stroke engine and 20-80 times the PM emission levels of the four-stroke

engine. The fuel injected two-stroke engine, in comparison to the carburetted two-

stroke engine, showed reduced levels of the regulated HC, NOx and PM pollutants,

but not a reduction in the level of PM-associated PAH emissions. The results

actually showed that the level of PM-associated PAH emissions were higher for the

fuel injected two-stroke engine. Also shown was that semi-volatile PAHs were

emitted by all the engines, with the carburetted two-stroke engine again measuring

the highest levels (Kado et al., 2000).

Investigations into the genotoxicity (mutagenicity) of the PM emissions found that

the activity of the PM from the fuel injected two-stroke engine was approximately 30

times that of the four-stroke engine. The activity of the PM emissions from the

carburetted two-stroke engine was found to be 45 times that of the four-stroke

engine. The emissions of the four-stroke engine were at a level only slightly higher

than the background level of PM-associated PAHs and mutagenic activity (Kado et

al., 2000).

West Virginia University conducted a study of the emissions from recreational

marine engines. Their aims were to identify and quantify the exhaust emissions from

a marine inboard four-stroke engine, and a two-stroke outboard engine, using



different types of water (tap, river and seawater). Both engines were tested with

exhaust gas/cooling water mixing (scrubbing) in the exhaust stream using each type

of water. This was to determine if this technique could reduce the emission levels to

the atmosphere. The group studied the gaseous emissions of HCs, NOx, CO and

CO2; and the carbonyl compounds and hydrocarbon species within the cooling water

(Mace, 2000).

Results showed that the difference in the gaseous emission levels was negligible

between using river or tap water for scrubbing. There was some difference however

in these levels between salt and tap water scrubbing, but the differences were

determined to be within the error margins of the experimental data, therefore no

conclusions could be reached (Mace, 2000).

Adopting the scrubbing technique of the exhaust gases resulted in a small reduction

in NOx and CO levels emitted to the atmosphere, however, an increase in CO2 of

approximately 2% was observed. Scrubbing also reduced the levels of formaldehyde

and acetaldehyde emitted to the atmosphere in the exhaust gases, but increased the

acetone levels by an order of magnitude (Mace, 2000).

It was further found that the two-stroke engine emitted 87 times more HCs into the

atmosphere than did the four-stroke engine, but emitted NOx at a rate 15 times less.

Emissions into tap water by the two-stroke engine were found to contain high levels

of acetone, but none were detected when salt water was used or in any tests

conducted on the four-stroke engine. The levels of ethanol, methanol, formaldehyde



and acetaldehyde in the water were found to be similar for both engines (Mace,

2000).

2.4.3 Australian Studies

A study undertaken by the University of Newcastle tested the fuel consumption rate

and the levels of emissions from 10 two-stroke and 6 four-stroke lawn mowers in a

laboratory. A further 19 two-stroke and 10 four-stroke lawn mowers were tested in

the field to compare the results with actual mowing conditions. The levels of CO,

CO2, CH4, NMHC (non-methane hydrocarbons) and NOx were determined (Priest et

al., 2000).

The results indicated that, on average, 34% of the fuel in a two-stroke lawn mower

short-circuited directly into the exhaust, whereas, only 8% of the fuel short-circuited

in the four-stroke lawn mowers. Therefore, the HC emission rate for two-stroke

lawn mowers was determined to be seven times greater than for the four-stroke

version.

Based on a survey of lawn care practices within the Newcastle area and the number

and types of lawn mowers in use, it was estimated that in comparison to local

transport sources, lawn mowers contribute 5.2% of CO and 11.6% of NMHC

emissions in the area (Priest et al., 2000).

2.4.4 Limitations within the Previous Studies

The previous studies have highlighted the significance of the emissions from two-

stroke engines, and in particular, the potential threats that they impose within the

marine environment. The studies have identified the individual components of the



emissions, in some cases the levels of these components, and the toxic effects that

they can have in both the short and long term.

These studies now serve as the starting point for refining our research strategy, and in

conjunction with broadening our base of knowledge through the literature review, aid

in identifying the next important step to be taken. Two main areas of concern arose

from the review of the previous studies.

Firstly, the studies to date have tested the engines at a constant throttle setting.

However, as reported previously, the rate of PAH formation will increase as the

air:fuel ratio decreases (Baird, 1999). Removing the spark plug from an engine

reveals that at lower revolutions a thick black coating builds up on it, and in turn the

efficiency of the engine decreases dramatically.

It is therefore hypothesised that a two-stroke engine will emit PAHs at a greater rate

when the engine is operated at lower revolutions than at higher revolutions. The

significance of this is that it has been determined that marine engines only spend 6%

of their operational time at full throttle, and 40% is spent at idle (Morgan et al.,

1990). Based on this, if the emission rate of PAHs is higher at low revolutions, then

the tests to date could be under - estimating the levels emitted under normal

operating conditions.

To test this hypothesis, the test procedure for the project has incorporated engine

tests at a variety of throttle settings and water samples taken and tested for each



setting. The engine test procedure was performed at the following settings 20%,

40%, 60%, 80% and full throttle.

Secondly, knowing the content of the emissions is important, but also knowing their

fate in the environment after emission is as equally important. None of the previous

studies has determined either the short or long term fate of these pollutants within the

marine environment, other than to determine their toxicity. Figure 4 shows an

underwater image of the exhaust gas emissions from an outboard engine. When this

image was taken the engine was running at low speed, and so there is no interference

from propeller tip cavitation. Figure 4 serves to illustrate the nature of the exhaust

emissions under the water, the dilution of which will be estimated.

Figure 4: An Underwater Image of the Exhaust Gases being emitted from the Hub of an Outboard Engine's Propeller(Rea, 2001)

After the dilutions of the pollutants have been determined for a variety of distances

behind the propeller, toxicity equivalence factors will be used to determine the

expected total toxicity of the pollutants at that point. The methods for these will be

discussed in the appropriate chapters. In order to arrive at a point where these can be

halla

This figure is not available online. Please consult the hardcopy thesis available from the QUT Library



determined however, other information such as engine power at the various throttle

settings is required. This type of information is not often available as was the case

for the two-stroke engine used in this project. To find this information for the two-

stroke engine it was necessary to undertake an engine modelling exercise. The

information was available for the four-stroke engine.

2.5 Engine Performance Modelling

Heywood, (1999), reported that the level of effort devoted to internal combustion

engine modelling and the capabilities of the resulting models have increased

dramatically over the last ten years. Engine performance modelling is accomplished

with the use of a set of mathematical equations. The set of equations represent the

governing fluid mechanics and thermodynamic behaviour of the engine working

fluid as it passes through the cylinder of an operating engine, which are solved

numerically on a computer (Heywood, 1999).

Heywood, (1999), noted that there are three phases of model development:

1. Model development through an analysis of the individual processes which are

linked together in the engine operating cycle

2. The exploratory use of the model, its validation, and studies of sensitivity of

model predictions to initial assumptions

3. The use of the model in extensive parametric studies which examine the

effects of changes in engine operating and design parameters on engine

performance, efficiency and emissions



A number of engine combustion model classifications have been proposed, and differ

due to the fact that different classes of combustion model are generally useful in

examining different kinds of combustion related problems, (Heywood, 1999).

The categories of combustion model are:

1. Zero-dimensional (sometimes called thermodynamic) models

2. Quasi-dimensional (sometimes called entrainment) models

3. Multidimensional (sometimes called detailed) models

Zero-dimensional and quasi-dimensional models are structured around a

thermodynamic analysis of the contents of the engine cylinder during the engine

operating cycle. Multidimensional models differ in that the governing partial-

differential conservation equations, along with appropriate sub-models that describe

the turbulence processes, chemical processes, boundary layer processes, etc., are

solved numerically subject to the appropriate boundary conditions. This type of

engine modelling will provide detailed information on the temperature, gas velocity

and composition within the combustion chamber of the engine during the combustion

process (Heywood, 1999).

A range of models exists that vary in complexity and data input requirements. Of

course the models that provide more accurate results, require an exhaustive level of

preliminary investigation in order to provide the appropriate input data. These types

of models are sometimes available as purchasable software packages, but are often

developed “in-house” using the governing equations and written into programming

languages such as FORTRAN. Further, these approaches are usually limited to more



technically difficult and detailed engines such as those produced by car

manufacturers, not simple two-stroke engine designs such as the engine used in the

this study. There have been modelling exercises undertaken for two-stroke engines

in the past however, and to varying degrees of complexity. A brief outline of the

methods is discussed, and the limitations of those are identified.

2.5.1 Two-Stroke Engine Performance Modelling

van Leersum (1998) reported that two-stroke engine performance modelling differs

from other types of engine modelling in that, it relies upon the way in which the duct

flows are modelled. The reason for this is because this type of engine relies on

pressure waves in the exhaust ducts to ensure that the cylinder is emptied of its

exhaust gasses, thereby filling the cylinder with a fresh charge of fuel/air mixture as

efficiently as possible, (van Leersum 1998).

Ideally then, a low-pressure wave is required to arrive at the exhaust port just after it

opens, and a high-pressure wave is required at that port some time before the exhaust

port closes. It is crucial therefore to model these pressure waves accurately because

the wrong exhaust duct can reduce the engine’s performance by 50%, (van Leersum

1998). van Leersum (1998) noted that traditionally there are two mathematical

methods that have been used to model duct flows within two-stroke engines;

isentropic and non-isentropic models.

Isentropic Models

An Isentropic process is one in which it is assumed that there is no heat transfer.

These models assume that the flow is isentropic everywhere in the duct, and they

suffer from the limitation that a reference temperature for each duct is required as an



input. The model then relates each duct temperature to its chosen reference

temperature, (van Leersum 1998).

van Leersum (1998) suggested that if the wrong reference temperature is specified,

then the wave speed will be in error, and therefore the model predictions will also be

in error. van Leersum (1998) suggested further however, that some guidance is

available for choosing the correct reference temperature, and when the correct input

is chosen, the model predictions are quite good.

Non-isentropic Models

These models use the method of characteristics and do not suffer the above

restrictions, however, van Leersum (1998) noted that the method of characteristics

generally has the following limitations:

• It has difficulties in modelling shock waves, contact discontinuities and transonic

flow without complicated “add-ons”. Such phenomena are common in two-

stroke engines.

• There is a need to “seed” the computational field with a large number of path

lines so that changes in temperature can be modelled correctly.

• Numerical smearing can occur because of the need to interpolate characteristic

positions between nodes when the mesh method of characteristics is used. The

natural method of characteristics causes problems with mesh points being non-

uniformly distributed in both space and time domains and is therefore used

infrequently.

A new numerical model that has been developed by van Leersum (1998) pays

particular attention to modelling the duct flows. It does this by using a flux



conservative type algorithm modified by the use of flux splitting and flux limiters,

and it does not have many of the restrictions of previous models identified in the

literature. The model is able to cope well with high specific power output engines,

and model predictions have compared well with a medium performance 100cc

engine and a high performance 125cc engine, (van Leersum 1998).

Probably its greatest benefit for this project is that it has been developed into a low-

cost software package called MOTA. It therefore has the advantage of saving

enormous amounts of time, in that, there is no need to write programs that use the

equations; a time consuming process that can take many months to accomplish. The

results from the modelling exercise are used to calculate an emission rate for the

pollutants.

2.6 Statistical Analyses

In order to make comparisons between the results obtained in this research, one of

the main objectives of the project, it is necessary to use statistical analyses so the

conclusions will not be subjective.

2.6.1 Chemometrics

The term chemometrics was first proposed in 1972. It was used to describe the

chemical field of research that used the application of mathematics and statistics for

chemical data interpretation (Kokot et al., 1998). In more recent times, with the

advent of computer-interfaced instrumentation that can generate data rapidly,

chemometric techniques have received wider attention. These techniques have been

applied in areas such as; the quality control of petroleum products, studying

oxidation, the preparation of soil samples by microwave digestion, the dying



properties of cotton fabrics, and in environmental projects related to the

determination of trace elements in water (which is in essence the primary objective

of this project) (Kokot et al., 1998).

2.6.1.1 Principal Components Analysis

Kokot et al., (1998) reported that Principal Components Analyses (PCA) is one of

the corner stones of chemometric techniques, and that it is arguably the most

common of the pattern recognition methods used in multi-variate analyses.

A PCA is a statistical technique for studying matrices of data, and is recognised as a

very powerful method that has been used for more than 50 years. The aim of a PCA

is to summarise the interrelationships among a number of variables in a concise but

accurate manner to aid in conceptualising the entire data set. It does this by linearly

transforming an original set of variables into a substantially smaller set of

uncorrelated variables that represents most of the information in the original set of

variables. More simply, it attempts to look for the least number of components that

contribute to most of the variance in the entire data set (Dunteman, 1989).

Kokot et al., (1998) stated that the essence of a PCA is:

• It is of considerable advantage if the dimensionality of the data is reduced

without any loss of information or data variance,

• Once the task is achieved, it is useful that the results can be presented

diagrammatically,

• It is desirable to have some indicators that are the likely important variables that

affect the entire data set,



• It is particularly useful to be able to observe the relationship of the samples and

the variables together.

Kokot et al., (1998) noted that to apply a PCA method to a data set, it must be

arranged into a data matrix with the selected variables defining the columns, and the

rows referring to the sample measurements. Doing this allows for “pre-treatment” of

the data, whereby, dividing each column by its standard deviation, the variables

become of equal weighting and have a standard deviation of 1.

After the data is transformed by the PCA, the new axes, called principal components,

are chosen such that principal component 1 describes most of the data variance;

principal component 2 describes the next largest amount, and so on. Each principal

component is then assigned all of the variables, which are normalised to a value of

between 0 and 1, and the criteria for variable acceptance is 0.65. This simply means

that if a variable, or a number of them, have values of 0.65 or higher, then they are

considered to be influencing variables to that particular component (Dunteman,

1989).

This method is particularly useful for this study because the main premise is to

conduct a comparison of the emissions at a range of throttle settings, when using

different lubricants. The result of this is, there are a large number of variables and

each variable has a large set of data associated. This inturn produces a large matrix

of data that is often difficult to interpret by simple visual and/or graphical means.

Kokot et al., (1998) noted however, that a statistical or a mathematical method will

process an array of numbers whether they are scientifically meaningful or not. It is



therefore up to the user to ensure that the data is of the appropriate quality; even then,

there may be nothing of significance to discover in the data set.


Chapter 3 – Equipment and Methodologies 50

CCHHAAPPTTEERR 33

Equipment and Methodologies

3.1 Experimental Equipment and Set-Up – Engines

This project had two main sponsors. Firstly, Fuchs Australia Pty Ltd was the

primary sponsor who supplied the lubricants used in the testing, and they arranged

for the donation of a 1.9kW two-stroke outboard engine from Mercury Marine

Australia. Fuchs also provided cash and in-kind support throughout the three-year

term of the study. Secondly, Honda Australia was kind enough to provide a 5.96 kW

four-stroke outboard engine so a comparison could be conducted between the results

from the two types of engines. Mercury marine also provided a test tank in which

the experiments were conducted. There were a number of components required to

set-up both of the engines for the testing procedures, including:

• Engine set-ups

• Measuring equipment such as

o RPM

o Fuel consumption rate

• Separate warm-up equipment /procedures.

The test tank was installed in the Thermodynamics High-Speed Engines Laboratory,

level 1 ‘O’ block, Queensland University of Technology Gardens Point Campus.

The plastic test tank came fitted with an internal aluminium support frame, clamped

to the tank with a pair of bolts, and two bungs. To facilitate the emptying of the tank

and to take water samples, one of the bungs was replaced with a valve as can be seen



in Figure 5. This also allowed water samples to be taken safely while the engine was

still running in the tank.

Figure 5: Test Tank Tap

The 1.9kW Mercury Marine Engine was new when donated to the project; its

specifications are, model designation MA 2.5 M, model number 7-002201JK,

manufactured in the year 2000. To achieve the correct running plane of the engine,

perpendicular to the surface of water, the engine mount was supported by a block of

wood, on the inside of the tank, as the running plane adjustment on the outboard has

limited travel. The four-stroke engine was adjusted to the correct operating plane

without the use of the wooden block.

The tank was then filled with town water, from a tap located within the High-Speed

Engines Laboratory, using a garden hose. The volume of water held in the tank was

calculated by finding out the average flow rate from the tap, and measuring the total

time taken to fill the tank to a set point, marked on the tank wall. The flow rate was

calculated by measuring the time period taken to partially fill a bucket. The bucket

was then weighed, and the weight of the bucket taken away from the net weight.

From this the instantaneous mass flow rate of water was calculated, this process was

continuously repeated over the total time taken to fill the tank, and the mass flow rate

averaged over the readings, this data is displayed below in Table 5.



Table 5: Test Tank Volume Calibration Sample Net Weight Mass Water Time Mass Flow Rate

No (kg) (kg) (s) (kg/s)

1 9.350 8.875 26.80 0.331 2 8.730 8.255 24.00 0.344 3 8.895 8.420 25.70 0.328 4 9.600 9.125 25.25 0.361 5 9.155 8.680 26.25 0.331 6 8.550 8.075 24.00 0.336 7 8.875 8.400 25.60 0.328 8 8.665 8.190 24.50 0.334 9 9.155 8.680 26.50 0.328

10 6.885 6.410 19.75 0.325 11 8.655 8.180 24.30 0.337 12 9.250 8.775 26.80 0.327

Bucket Weight (kg) 0.475 Average Mass Flow Rate (kg/s) 0.334 Total Filling Time (s) 1962 Total Water Volume (L) 656

Note: the valve opening was constant during filling; variations in flow rate would be

due to the dynamics of the supply system and the varying demands placed on it.

The volume of water in the tank was calculated to be approximately 655L.

As previously noted, the two-stroke engine was new when it was received; therefore

it had to be run-in prior to tests being conducted. For the run-in procedure the oil

fuel ratio was 1:25 as recommended by the manufacturer; for normal operation the

fuel ratio is 1:50. The run in procedure was then carried out in accordance with the

manufacturer’s specifications. The engine was run continuously for one hour, with

the throttle being maintained in one position for no more than two minutes.

When the engine was first started it became apparent that the laboratory extraction

fans were not effectively removing the exhaust gases. Smoke could be seen

dispersing into the room from the tank and the emissions could be smelt. Due to the



risk of carbon monoxide poisoning, it was decided to improve the exhaust gas

extraction set-up.

A plastic exhaust extraction line was added to the tank with the inlet at the opposite

end of the tank from the engine – to draw air in from the motor end. This line was

routed to an extraction point located on an adjacent engine test rig; the exhaust

extraction fan evacuates exhaust gases from engines in operation in the High-Speed

Engines Laboratory to the roof of the building. With this fan running no emissions

could be seen coming from the tank or smelt in the room.

Prior to the beginning of testing the wooden items located inside the tank were

wrapped and sealed in plastic because it was thought that they may be capable of

affecting the results. It was thought that because wood is porous it could absorb and

re-release compounds into the tank. The original rubber splashguard on the test tank

was replaced with a plastic sheet also, because the rubber guard might react with

some compounds.

To measure the operating characteristics of the engine the following instruments

were set up. A digital tachometer, ‘Digitech’ model number QM1440, was

purchased from an electronics supplier. This was set up on the marine engine; it

measures the pulses from the magneto. (A magnet is located on the flywheel; this

electrical pulse is used to adjust engine timing and to provide the charge for the spark

ignition system, similar to most lawn mowers). Two electrical wires were added to

the engine, one from the earth and the other from between the magneto and the

ignition system. The former fixed to a bolt and the latter plugged into an electrical



fitting already in place, these wires are not permanent additions to the engine and can

be easily removed. The tachometer is connected to these two wires as per the

manufacturer’s specifications. It was calibrated by using a manual (physical contact)

tachometer.

A burette was set up so that the rate of fuel use of the engine could be measured. A

barbed t-piece was added immediately after the fuel cut off switch on the tank; see

Figure 6, complete with a new segment of fuel line. This arrangement allows either

the burette or the fuel tank to supply fuel to the engine. The t-piece and fuel line was

purchased from specialist suppliers, fuel line clips and clamps were also purchased to

prevent fuel leaks and maintain the arrangement during engine operation.

Figure 6: Fuel Line Modifications (Rea, 2001)

From the t-piece the original fuel line continued to the carburettor. A new fuel line,

complete with an isolation switch immediately after the t-piece and a 1.5m long

segment, connected the t-piece to the 50mL burette. The burette is located on a stand

next to the test rig at a level higher than the fuel tank. Note: The carburettor holds

approximately 10mL of fuel; care must be taken to ensure that the carburettor is full

before using the burette otherwise the fuel usage readings will be inaccurate. A

stopwatch, ‘JADCO Electronic clock timer’, was used to time the fuel consumed by

the engine.

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When the tests were conducted in the field, a bilge pump was used to fill and empty

the test tank with local seawater. A ‘L2200 Johnson’, was purchased from a marine

supplier, and 25mm clear plastic tubing purchased from a hardware store. The pump

was selected on the basis of its high flow rate (relatively quick tank emptying time),

electricity supply – 12V DC, and reliability, being a recognised brand. Figures 7 and

8 show the complete experimental set-up.

Figure 7: Two-Stroke Outboard Engine Test Rig - Rear View

Figure 8: Two-Stroke Outboard Engine Test Rig - Front View

Test Tank

Engine

Tachometer

Burette

Exhaust Extraction

Line Splash Guard

Submersible Pump



As the tests that were conducted require a range of throttle settings a method of

ensuring repeatable throttle settings was needed. The carburettor on the two-stroke

engine has a throttle pin, which travels up and down to control the throttle opening.

This pin is actuated by the throttle arm, which is moved by the user, up and down, as

required. This up and down travel on the throttle pin was measured, which directly

corresponds to the opening in the carburettor (see Figure 9). It was measured from

wide-open (100%) throttle to idle (assumed to be 20% throttle: as per the Marine

Duty Cycle (Morgan et al. 1990)). This length of travel was then divided into four

equal segments to obtain the throttle settings of 20%, 40%, 60%, 80% and 100%

throttle.

Figure 9: Carburettor Throttle Pin Travel (Rea, 2001)

To ensure repeatability of the throttle setting tests, a set of fit/no-fit throttle gauges

were manufactured. The throttle gauges were machined from brass to be the same

diameter as the throttle pin and are illustrated below in Figure 10.

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Figure 10: Throttle Setting Gauges (Rea, 2001)

These gauges are kept on a ring, in side the engine cover, and tied to the engine

frame. The throttle pin is spring-loaded and once the throttle gauge is in place,

adjacent to the throttle pin, and the throttle arm moved to the 20% throttle setting the

throttle gauge will be held in place. For safety sake a bulldog clip was also used to

clip the gauge and the pin together.

It is expected that the emissions from a cold engine would be significantly different

from the emissions of an engine at operating temperature. To achieve reliable results

the engine must be warmed up for 5 minutes prior to conducting emission tests. If

the engine were to be warmed up in the test tank then background emission levels

would have to be determined by sampling the water. However this would increase

experimental error, as the emissions from the engine during warm-up would be

subtracted from those during the trial, yet the errors would combine.

Alternatively the tank would have to be emptied, scrubbed clean and refilled – a time

consuming process, by the end of which the engine would need to be warmed up

again. It was decided to run the engine in another location immediately before the

start of the trial. A warm-up stand was constructed from steel angle so the engine

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could be run in a small plastic container outside the building; the stand is illustrated

below in Figure 11.

Figure 11: Warm-Up Stand (Rea, 2001)

This frame also doubles as a convenient stand for the engine.

Note: care must be taken during engine operation to ensure that the tachometer wires

do not earth to the stand – the magneto can supply a strong shock, especially in the

presence of water. The best plan of action is to unplug the tachometer wires from the

engines before using the warm-up stand.

The Honda four-stroke engine was set-up in almost exactly the same manner as the

two-stroke engine. There were few exceptions: the first was that a 100mL burette

was used instead of the 50mL burette due to an expected increase in the rate of fuel

consumption, the second was that the throttle on the tiller arm was marked for the

different throttle setting tests. This was because there was no suitable position to

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locate throttle gauge pins on the carburettor. To position the marks on the tiller arm,

the throttle was locked in the idle position. From this position the throttle level on

the carburettor, which is attached directly to the butterfly valve inside the carburettor,

was rotated and its angle of rotation recorded using a protractor. The angle of

rotation was then divided by four to give the number of degrees of rotation for each

of the remaining throttle settings. The throttle on the tiller arm was then rotated until

the level arm on the side of the carburettor had rotated the appropriate number of

degrees, and then the throttle on the tiller arm was marked. Figure 12 shows the set-

up of the four-stroke engine in the test tank.

Figure 12: Set-up of the Four-Stroke Engine Experimental Equipment for the Fuel Consumption and Engine Tests

Figures13 and 14 below shows the marked throttle on the tiller arm. To ensure

consistency in the test, two additional marks were engraved onto the throttle locking

nut. When these lines were lined up, and the throttle then moved to the required

setting, it would be locked into position with confidence. The rpm readings were

used as a check for the correct position. It needs to be kept in mind that throttle



cables stretch, and therefore, periodic checks using the protractor will need to be

conducted for future tests.

Figure 13: Four-Stroke Engine Throttle Settings on Tiller Arm – Side View

Figure 14: Four-Stroke Engine Throttle Settings on Tiller Arm – Top View

One other difference between the two set-ups was in the method of warming up the

engine. Where the shaft of the two-stroke engine was emersed in a drum full of

Line-up marks on locking nut

Throttle locked at 40% setting

Line-up marks on locking nut



water, the four-stroke engine simply had “muffs” connected to a hose clamped

around the cooling water intake vents for the engine. Figure 15 shows the set-up.

Figure 15: Four-stroke Engine Warm-up Configuration

3.2 Fuel Consumption Tests

The equipment used and the procedure adopted for the laboratory and field tests were

the same except the engine was used on a boat instead of the test tank for the field

tests; Figure 16 shows the set-up for the field tests.

3.2.1 Procedure

• The test tank was scrubbed clean and filled with fresh tap water.

• From empty, the fuel tank of the engine was filled with the correct fuel/oil

mixture as per the engine manufacturers’ specifications.

• The engine was then mounted in the test tank and, initially at 100% throttle

using the throttle pin spacers manufactured, testing commenced.

• The fuel was drawn from a 100mL burette for a period of one minute, and the

volume of fuel used recorded.

• This was then repeated for the other throttles settings of 80%, 60%, 40% and

20%.



The procedure was repeated three times for the two-stroke engine for each of the two

lubricants used, both in the laboratory and in the field. The procedure was also

repeated three times for the four-stroke engine when using a standard mineral

lubricant, but only in the laboratory.

Figure 16: Set-up of the Two-Stroke Engine on a Small Timber Boat that was used for the In - Field Fuel Consumption Tests

3.3 Preliminary Pollutant Investigation

A preliminary investigation was conducted to identify the pollutants that remained in

the water column; these then became the focus of the detailed investigation for the

rest of the project (Kelly et al., 2001a, Kelly et al., 2001b). The preliminary

investigation looked for more than seventy compounds, and was conducted at the

Australian Government Analytical Laboratories (AGAL). The USEPA Method 610

was used for the chemical analysis.

3.3.1 Equipment and Procedure

The equipment that was used for the experiments was the same as was used for the

fuel consumption tests (Figures 7 & 8). The procedure that was used follows:




• Prior to the first run, a sample of the water was taken from a valve located on

the lower left side of the test tank prior to the engine being mounted in the

tank. This served as a blank sample to determine the background levels of

the compounds being sought. A run is considered a set of experiments

consisting of 100%, 80%, 60%, 40%, and 20% throttle settings.



• In a separate warm up tank, the engine was run for 5 minutes to reach

operating temperature.

• The engine was removed from the warm up tank and rinsed and wiped clean

to ensure that no cross-contamination of the test tank water occurred.



• The engine was run for ten minutes, and while the engine was still running,

two water samples were taken from the previously mentioned valve for the

analysis. The turbulence in the tank was extreme and therefore mixing was

assumed to be complete.

• After the samples were taken, the engine was stopped and removed from the

test tank.

The results from AGAL showed that there were two types of compound that required

a detailed investigation, Volatile Organic Compounds (VOCs), and Polycyclic

Aromatic Hydrocarbons (PAHs). The detected concentrations of VOCs was high,

however, the detected levels of PAHs was low and it was decided to extend the

running time of the engine for the analysis of PAHs to twenty minutes instead of the

previous ten minutes (Kelly et al., 2001a, Kelly et al., 2001b).



3.4 Two – Stroke Engine Laboratory Tests

The equipment set-up and the experimental procedure that was used proved to be

appropriate for the rest of the experiments except for the minor alteration in running

time for the PAH samples.

3.4.1 Equipment and Procedure

The equipment that was used for the experiments was the same as that used for the

fuel consumption tests (Figures 7 and 8). The following procedure was then used:


• Prior to the first run, a sample of the water was taken from a valve located on

the lower left side of the test tank prior to the engine being mounted in the

tank. This served as a blank sample to determine the background levels of

the compounds being sought. A run is considered a set of experiments

consisting of 100%, 80%, 60%, 40%, and 20% throttle settings.



• In a separate warm up tank, the engine was run for 5 minutes to reach

operating temperature.

• The engine was removed from the warm up tank and rinsed and wiped clean

to ensure that no cross-contamination of the test tank water occurred.



• The engine was run for ten minutes, and while the engine was still running, a

water sample was taken from the previously mentioned valve for the analysis

of VOCs. The engine was left running and another water sample taken after

twenty minutes for the analysis of PAHs, again while the engine was running.



• After the samples were taken, the engine was stopped and removed from the

throttle setting test.

• Prior to the next test, the spark plug was removed from the engine and

cleaned if required. The spark plug gap was checked, and if required, re-set as

per the engine manufacturers’ specifications.

• This procedure was conducted for the remaining throttle settings of 80%,

60%, 40%, and 20%, to complete the run.

• After the 20% throttle setting test, the test tank was again scrubbed clean,

refilled with fresh tap water, and another blank water sample taken prior to

the commencement of the next run.

This entire procedure was conducted three times each for a mineral marine two-

stroke engine lubricant and an equivalent environmentally marine two-stroke engine

lubricant.

3.5 Two – Stroke Engine Field Tests

The tests that were conducted in the laboratory used fresh tap water to simulate the

emissions to a fresh water body. It was decided to compare the emissions to

seawater to determine if there was either an increase or a reduction in the emissions

to seawater.

3.5.1 Field Test Site

The field experiments were conducted at Redland Bay, South East Queensland,

Australia. Figure 17 shows the location of the test site, which the Queensland

Environment Protection Agency has defined as a typically coastal region.



Figure 17: Shows the Location of the Test Site

3.5.2 Field Test Equipment and Procedure

The experiments conducted in the field were a scaled down version of the above.

Engine tests were conducted at throttle settings of 20%, 60% and 100%, with three

tests conducted at each setting. Also, blank water samples taken to determine

background levels. Further, it was determined to only analyse for PAH

concentrations since the laboratory experiments revealed that the concentrations of

VOCs were due primarily to the fuel fraction of the fuel/oil mixture. The tests were

conducted using only the two-stroke engine, and the set-up and procedure were the

same as the laboratory tests. Figure 18 shows the experiment set-up in the field.

Field - Test Site Location



Figure 18: On Site Field Experiments in Progress

3.6 Four – Stroke Engine Tests

The four-stroke engine tests were conducted in the laboratory, and the results were

compared to the results of the two-stroke engine tests.

3.6.1 Equipment

The experimental set-up for the four-stroke engine tests was the same as for the two-

stroke tests (Figure 12).

3.6.2 Procedure

The same procedure as the two-stroke engine test procedure was used for the four-

stroke engine tests.

3.7 PAH Identification and Quantification

3.7.1 Preparation of the Water Samples for Analysis

The water samples were collected in glass amber bottles and tightly sealed.

Immediately after collection, each sample was refrigerated and stored for later

analysis at a temperature below 4°C. The analysis of the PAH samples was



conducted in the Queensland University of Technology chemistry laboratories. The

USEPA Method 610 – Polynuclear Aromatic Hydrocarbons, in Methods for Organic

Chemical Analysis of Municipal and Industrial Wastewater, (1995), was used. This

method was adopted so the results could be compared to those of preliminary tests

conducted (Kelly et al., 2001a, Kelly et al., 2001b). The work was conducted under

the supervision of Dr Godwin Ayoko, of the School of Chemical and Physical

Sciences.

3.7.2 Extraction Procedure

The following solvent extraction procedure was used to extract the PAHs from the

water samples.

• A 100mL volume of the sample water was poured into a separatory funnel.

• 10mL of dichloromethane was added to the sample bottle, re-sealed, and then

shaken for 30 seconds to rinse the inner surface. The solvent was then

transferred to the separatory funnel and then extracted by shaking the funnel

for two minutes with periodic venting to release excess pressure. The organic

layer was allowed to separate from the water phase for a minimum of 10

minutes. The extracted sample volume was collected into a conical flask.

• A second 10 mL of dichloromethane was added to the sample bottle and the

extraction procedure repeated a second time, combining the extracts in the

conical flask. A third extraction was performed in the same manner.

• 500mg of sodium sulphate drying agent was added to the conical flask.

• The extract was then filtered into a round-bottomed quick fit flask.

• The extract was evaporated to dryness using a rotary evaporator.

• The quick fit flask was then rinsed with 1.5mL of methanol and the contents

transferred to an auto-sampler vial and sealed.



• The extracted samples were then refrigerated until analysis took place.

3.7.3 Sample Analysis

The water samples were analysed using a Hewlett Packard 6890 Gas Chromatograph

(GC) with a Flame Ionisation Detector (FID). The unit was connected to a computer

running the HP GC Chemstation software, which controlled the operation of the

system. The capillary column installed in the GC was a Restek Rtx – 5MS, which

has a maximum temperature of 350ºC, a nominal length of 30m, a nominal diameter

of 320μm, and a nominal film thickness of 0.25μm.

The system was run in constant pressure mode at 74.03 kPa, with a nominal initial

flow of 2mL/min and an average velocity of 35cm/sec. Splitless injection mode was

used and the gas type was helium. A 1μL injection of a sample was introduced into

the GC with an initial oven temperature of 80ºC. After 4 minutes at this temperature,

the oven was “ramped up” at a rate of 10ºC/min to a final temperature of 320ºC, and

then held at this temperature for a further 10 minutes. This produced an overall run

time for each sample analysis of 38 minutes.

Prior to the samples being run through the GC, a standard mix of the compounds of

interest was analysed. The standard mix consisted of the following compounds at the

known concentration of 100μg/mL for each: acenaphthene, anthracene,

acenaphthylene, benz(a)anthracene, chrysene, benzo(a)pyrene, benzo(b)fluoranthene,

benzo(ghi)perylene, benzo(k)fluoranthene, dibenz(ah)anthracene, fluoranthene,

fluorene, indeno(123-cd)pyrene, naphthalene, phenanthrene, pyrene.



Once this analysis was complete a calibration table was developed that showed,

amongst other things, the order in which each of the compounds appeared on the gas

chromatograph, and their retention times. The samples were then analysed with

reference to the calibration data. After every 12 samples the standard mix was again

analysed and the concentrations in the subsequent 12 samples were corrected. For

example, the known concentration of naphthalene in the standard mix was

100μg/mL. If it was detected at a concentration of 98μg/mL the next time the

standard was run, the concentration of naphthalene in the next 12 samples was

adjusted up by 2%. All of the compounds were adjusted in the same manner. The

concentrations of the compounds found in the blank samples were also corrected in

the same manner and then subtracted from the data obtained for that run.

3.7.4 Efficiency of the Extraction Procedure

To determine the recovery efficiency of the extraction procedure, three 100mL

deionised water samples were “spiked” with 0.1mL of a 2000μg/mL standard mix of

the compounds of interest; thus providing a known concentration of 200μg/mL in

each bottle. A blank sample of the water was also prepared. The four samples were

extracted using the above procedure and then analysed. Once analysed, the recovery

efficiency was simply determined by dividing the analysed concentration by the

known concentration to give the fraction recovered. The analysed results were then

adjusted to account for the inefficiency of the extraction procedure.

3.7.5 Calculations

The data obtained from the analyses were provided in terms of parts per million

(ppm); these had to be corrected based on the sample volume and the extracted



volume from the above procedures. Example calculations for this can be found in

Appendix A; the calculation procedures follow.

The first step is to correct the detected concentrations of each of the compounds as

described above, starting with the concentrations in the blank samples.

conc

concb D

KC = * Bconc ……………………………. (1)

Where: Cb = Corrected concentration in the blank water sample (μg/mL)

Kconc = Known concentration in the standard mixture (μg/mL) Dconc = Detected concentration in the standard mixture (μg/mL) Bconc = Detected concentration in the blank sample (μg/mL)

Next is to correct for the detection error in the water samples analyses.

conc

concn D

KC = * Nconc ……………………………. (2)

Where: Cn = Corrected concentration in the test water sample: n refers to the

throttle setting (μg/mL) Kconc = Known concentration in the standard mixture (μg/mL) Dconc = Detected concentration in the standard mixture (μg/mL) Nconc = Detected concentration in the test sample (μg/mL)

Next the corrected blank concentration is subtracted from the corrected test sample.

bnn CCC −=& ……………………………. (3)

Where: nC& = is the amended concentration in the test sample (μg/mL) The actual concentration above is expressed in terms of μg/mL; however, this

represents the concentration in the extracted sample and not the actual concentration

that occurs in the test tank. Given that we know the sample volume and the extracted

volume, we can determine the actual concentration in the test tank water as follows.

( )sample

extractntank V

VCC *&& = ……………………………. (4)

Where: kCtan

& = is the amended concentration in the test tank (μg/mL)



nC& = is the actual concentration in the test sample (μg/mL) Vextract = Volume of the extracted sample (mL) Vsample = Volume of the water sample taken from the test tank (mL)

The next correction was made to account for the recovery efficiency and the

subsequent value expressed in terms of μg/L.

mLCCrecovery

tankactual 1000*1* ⎟⎟⎠

⎞⎜⎜⎝

⎛=

η& ……………………………. (5)

Where: Cactual = is the actual concentration in the test tank (μg/L)

tankC& = is the amended concentration in the test tank (μg/mL)

recoveryη = is the recovery efficiency for the specific compound of interest

Note: the recovery efficiency for each of the compounds is different.

The above value represents the concentration in the test tank; a figure not of much

use because it is an amount confined to a finite volume of water. Realistically, this

amount of pollutant would be dispersed into some undefined volume of water, and

hence more calculations are needed.

It was decided to express the results as an emission rate that could eventually be

related to all outboard engines of this design. The first step to doing this was to

express the results as an amount of pollutant emitted per litre of fuel/oil mixture

consumed; the calculation follows.

( ) actualFC CTFC

LLmLC *

*1*

11000

=& ……………………………. (6)

Where: FCC& = is the amount of pollutant emitted per rate of fuel consumption (μg/L of fuel consumed)

Cactual = is the actual concentration in the test tank (μg/L) FC = is the rate of fuel consumption at a particular throttle setting

(mL/s)



T = is the length of the test (s)

The final conversion was to express the result as an emission rate; the calculations

follow.

gg

PwrFCCE FCn μ1000000

1*1**&& = ……………………………. (7)

Where: = nE& is the emission rate of the particular pollutant at the particular throttle setting (μg/kW.hr)

FCC& = is the amount of pollutant emitted per rate of fuel consumption (μg/L of fuel consumed) FC = is the rate of fuel consumption at a particular throttle setting (mL/s) Pwr = is the engine output power at the particular throttle

setting (kW)

3.8 VOC Identification and Quantification

Envirotest Australia Pty Ltd using the solid phase micro-extraction procedure

conducted the analysis of the VOCs samples.

3.9 Raw Fuel and Oil Analyses

The concentrations of PAHs and VOCs in the raw oils and fuel were determined

using the same procedures and analytical techniques as above. These results were

used to determine what fraction of what was given to the engine was again emitted as

a pollutant.

3.10 Engine Performance Modelling

The “MOTA” software is used to simulate the performance of single cylinder two-

stroke engines. It will also simulate one of the cylinders of a multi-cylinder two-

stroke engine if the cylinders are identical in layout and dimensions, and each

cylinder has a separate exhaust and induction system. Further, it allows simulation



of engines with reed-valves, rotary-valves and piston port timed induction systems.

To use this software, the engine had to be completely dismantled and all of the

engines’ components measured for the input parameters for the program. Appendix

D shows the measurements of the components, while Figure 19 shows the dismantled

engine.

Figure 19: The Dismantled Two-Stroke Engine ready for Component Measurement

The MOTA software is a menu driven environment that prompts for the required

dimensions, which are needed for the equations. The output from the software is

provided in two forms:

1. A file that summarises the engine geometry and performance

2. A graphical interface that allows graphs to be plotted

The initial input data for the model was engine configuration. In this section,

induction type, exhaust system type, induction box and number of transfer port types

are to be entered.



Figure 20: Engine Configuration Data Box

Induction Type

Figure 20 shows the display screen of the engine configuration data box. The engine

in this project uses a reed valve induction system. A schematic diagram and detailed

explanation of reed valves is discussed later.

Exhaust System Type

The two-stroke outboard engine for this study uses a box muffler to control the

exhaust flow; box mufflers are the simplest and least expensive exhaust system to

manufacture. A box muffler is a cavity, which is usually circular or rectangular in

cross section, with an entry pipe from the engine and an exit pipe to the atmosphere.

Number of Transfer Port Types

The two-stroke engine used in this project has one type of transfer port. There are

two individual transfer ports inside the engine but they are identical and symmetrical

so their physical attributes can be described together.



Induction Box

An induction box is a ‘still air box’. Induction boxes use the forward velocity of a

vehicle to ‘supercharge’ the incoming air. The engine in this project, like most two-

stroke outboard engines, does not have an induction box.

Figure 21: Basic Engine Dimension Data Box

Basic Engine Dimensions

The most important physical aspect of the engine is the piston and the connecting

rod. These transmit the indicated power from the ignited gases to the crankshaft,

which in turn, transmits the brake power as an applied load. Therefore, the

measurement of these parts must be accurate in order to have a correct output file for

the modelling software. Figure 21 shows the required input information.

Crankcase Clearance Volume

The crankcase clearance volume was manually calculated using the measured

dimensions and engine geometry. It is the volume below the piston crown when the

piston is at the bottom dead centre (BDC).



Cylinder Clearance Volume

Cylinder clearance volume is the volume above the piston crown (with the spark plug

installed) when the piston is at top dead centre (TDC). This was also calculated

based on the measured engine components and geometry.

Figure 22: Ignition and Combustion Details Data Box

Next the ignition and combustion details were entered (Figure 22).

Combustion Efficiency

The combustion efficiency of an engine is a measure of the combustion chamber

effectiveness. It indicates how well the chamber design promotes the conversion of

the chemical energy of the raw fuel into heat energy that the piston can convert into a

driving force.

The user manual supplied with MOTA suggested values for the combustion

efficiency ranging from 0.8 (for high performance engines with long exhaust port

timings) to about 0.85 for more conservatively timed engines. The value adopted

was 0.85 because of the very basic design of the engine used in this project.



Burn Period

The burn period is the total number of crankshaft degrees over which the actual

combustion takes place. The suggested values in the MOTA user manual for burn

period vary between 60 degrees for a conservatively ported engine, to 50 degrees for

a high performance engine. The value chosen was 60 degrees for the same reason as

the combustion efficiency.

Ignition Timing - Number of Points defining the Ignition Characteristic

The MOTA input for ignition timing allows for a variable ignition timing sequence.

Typically, the piston settle time will reduce as the RPM increases, so for optimum

timing of the peak pressure in the combustion process, the ignition advance would

have to increase as the RPM increases (the burn period is assumed to be relatively

constant). Simple and inexpensive engines such as the engine used in this project

however, usually use a fixed ignition advance since they are only expected to do

useful work at near full throttle and peak RPM. Therefore constant ignition advance

was assumed, so the value of ONE was entered in the data box to show that the

advance is constant.

Ignition Timing – Degrees Below Top Dead Centre (BTDC)

This parameter was one of the variables that were used to “fine-tune” the model.

Although shown as 20° BTDC in Figure 22, the value of 25° BTDC was used in

obtaining the final results. The suggested values in the MOTA user manual for this

type of engine ranged from 20° to 30°, so three files were created to show the effect

of the timing on the output power. Figure 23 shows that there is little difference in

output power between the three settings; therefore 25° BTDC was finally used.



Figure 23: Comparison of Output Power at Different Ignition Timing

Figure 24: Ambient Condition Data Box

The ambient conditions such as air pressure and air temperature are entered into the

program and are presented in Figure 24.

Power vs Speed

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Speed (Rpm)

Pow

er (k

W)

30 degree BTDC 25 degree BTDC 20 degree BTDC



Air Pressure

The ambient air pressure directly affects the volumetric efficiency of any engine.

The fixed volume chambers in the engine will draw in fixed volumes of gases,

therefore, if the densities of those gases changes then so will the mass of the gases

that are inducted into the engine. An increase in ambient air pressure will cause the

engine to develop more power. In this study however, the air pressure used is the

standard atmospheric pressure, which is 101325 Pascals, given the simplistic design

of the engine, and the location of the tests.

Air Temperature

The inlet air temperature has a direct effect on the engine’s output by changing the

volumetric efficiency. A decrease in air temperature will cause the air to be denser

and thus more is induced in a fixed volume; furthermore, the amount of fuel induced

will rise in proportion to the increased mass of air induced. During the time the tests

were being conducted the air temperature ranged from 18°C to 21°C. It was decided

that a value of 20°C would be adopted for the modelling exercise.

Water Cooled Exhaust

The purpose of cooling the exhaust gas is because exhaust temperature in some

instances can be very high. Simple and small engines such as the two-stroke engine

used in this project do not require exhaust cooling.



Figure 25: Fuel and Scavenge Details

Fuel and Scavenge Details

Figure 25 shows that the MOTA scavenge model requires four scavenge parameters

to be input, as well as other information such as air/fuel ratios and calorific values.

Scavenge Parameters

The first value represents the maximum fraction of incoming flow from the transfer

ports to the cylinder, which will short circuit directly to the exhaust duct without

taking part in any mixing or displacement processes in the cylinder. This maximum

short circuit fraction usually lies between 0 and 0.2, and for most high performance

engines the value will be zero. For older engines or lower specific power output

engines, the MOTA user manual recommends a value of 0.2. An average value of

0.1 was adopted because, while the engine in this case is of a simple design, it is a

new engine.



The second value is the inflow displacement fraction that represents the maximum

fraction of incoming flow; this promotes displacement scavenging. Displacement

scavenging is the bulk movement of exhaust gas going out of the cylinder and into

the exhaust port. This is distinguished from mixing scavenging by the fact that there

is an interface between the fresh incoming gas and the exhaust gas, hence there is no

mixing of the two gases across this interface. The suggested values are from 0.8 to

1.0, so again the average value of 0.9 was adopted.

The third value is the short circuit cut-off, which is a measure of how far into the

scavenge cycle the short-circuiting flow falls to zero. This value must always be

greater than zero because short-circuiting is always present in two-stroke engines. It

is usually only fractionally less than 1.0; however, the MOTA manual suggests that

for simple engines a value of 1 be adopted.

The fourth scavenge value is the scavenge cut-off, which is the measure of how far

into the scavenge cycle displacement scavenging stops and perfect mixing controls

the whole process. The MOTA user manual suggested that high performance

engines usually have values of 0.7 to 1.0 and low performance engines are from 0.4

to 0.7. Given that the two-stroke engine used in this project was considered low

performance, the value of 0.4 was selected.

Fuel Calorific Value

Fuel calorific value, or fuel heating value, is defined as the amount of heat released

when a fuel is burned completely in a steady flow process, and the products are



returned to the state of the reactants (Cengal and Boles, 1998). The default value for

the fuel calorific value is given as 10300 kcal/kg in the MOTA user manual.

Throttle Setting

Throttle setting, or throttle area ratio, is the fraction of the carburettor passage area

open to flow. It varies from zero when the throttle is closed, to a value of one when

it is fully open. The throttle setting simulations conducted in this project were

accomplished by adjusting the diameter of the inlet duct. This was because the

throttle area ratio setting in MOTA only allowed for one decimal place, which meant

one significant figure was lost, thereby reducing the accuracy in the inlet flow

diameter.

The method adopted was to leave the throttle area ratio fully open and make the inlet

diameter smaller, and therefore more accuracy was achieved. The increase in wall

friction caused by having a short inlet pipe (16mm) with a restricted diameter was

considered negligible because the entry diameter was far more influential on the

volumetric efficiency than the small increase in skin friction on the duct wall.

Air-Fuel Ratio Details

Number of Points Defining the Air-Fuel Ratio Characteristic

In this section, the number of points defining the air-fuel ratio characteristics is a

function that allows the use of different air-fuel ratios at different speeds. In this

case however, the MOTA user manual recommended a value of 1.0.

Air-Fuel Ratio

The air-fuel ratio is defined as the ratio of the mass of air to the mass of fuel for a

combustion process (Cengal and Boles, 1998). The MOTA user manual has



recommended values for the air-fuel ratio for petrol from 11 to 13. A value of 11.5

was used. As a check as to the validity of using this value, the stoichiometric air-fuel

ratio was calculated for the two-stroke engine used in this project; the details follow.

Stoichiometric Air-Fuel Ratio

A stoichiometric or theoretical mixture of air and fuel is one that contains sufficient

oxygen to burn all of the carbon in the fuel to carbon dioxide, and all of the hydrogen

to water. A mixture that has an excess of air is called as lean mixture, and one that

has insufficient oxygen is called as rich mixture. The assumptions that were made

when performing the calculation for this engine are:

1. Combustion is complete

2. Combustion gases are ideal gases

3. The fuel is burned with the stoichiometric amount of air and thus there will

no free oxygen in the product gases.

( ) 22222188 76.39876.3 NaOHCONOaHC thth ++→++

Where: ath = 12.5 Substitute back into Equation

( ) 22222188 479876.35.12 NOHCONOHC ++→++

Air-fuel ratio = fuel

air

mm

=hydrogencarbon

air

Mass)Molar x mloes of(Number Mass)Molar x moles of(Number Mass)Molar x Moles of(Number

+

= ( )( ) ( )29128

2976.45.12×+×××

= 15.14 kg of air/kg of fuel



The stoichiometric, or theoretical, air-fuel ratio is therefore 15.14 kg of air per kg of

fuel. This air-fuel ratio is the chemically correct amount of air per kilogram of fuel,

and accounts for a perfect mass balance of the two reactants. However, practical

considerations require a diversion from the chemically balanced state. Examples of

these include; the rate of pressure rise, peak pressure, peak temperature and the

presence of pollutants (gasses such as HC and NOx). The reason for the difference

between both air-fuel ratios is mainly because the actual engine runs differently as

conditions within the cylinder change, and many other factors need to be accounted

for, which the theoretical air-fuel ratio does not consider.

The software was run 3 times varying the air-fuel ration between 11 and 13. The

results show that the output power of the engine will vary considerably with air-fuel

ratio. As the value of air-fuel ratio increases, there was a decrease of output power at

the same RPM (Figure 26). Based on the rated output power of the engine (1.9kW

at 100% throttle), this confirmed that the value of 11.5 for the air-fuel ratio adopted

earlier was correct.



Figure 26: Comparison of Different Air-Fuel Ratios

Figure 27: Run Parameters Data Box

Simulation Run Parameters

Output Units

MOTA allows the output values to be displayed in either metric or imperial units in

the output files; standard S.I. units were selected.

Power vs. R.P.M

00.10.20.30.40.50.60.70.80.9

11.11.21.31.41.51.61.71.81.9

22.12.2

0 1000 2000 3000 4000 5000 6000

R.P.M

Pow

er a

t Cra

nksh

aft (

kW)

Air Fuel Ratio = 13 Air Fuel Ratio = 12 Air Fuel Ratio = 11



Pipe Step Factors

The flow of air, air/fuel mixture and exhaust gases through the engine is modelled

mathematically by an engine simulator in the modelling software. The fluid flow

model requires the user to provide a value known as the pipe step factor, which

remains constant throughout the simulation. This value affects the run time and

accuracy of the program. The MOTA user manual suggests that using the shortest

length of pipe will provide a good compromise between run time and accuracy. The

upper and lower limits provided are 1.6 and 6.6 respectively; MOTA suggests that by

selecting a value nearer to the upper limit more accuracy will be achieved. The value

of 5.5 was chosen because run-time was not a concern, and there was little difference

in the results between the values of 6.6 and 5.5, but there was a significant saving in

run-time.

Number of Engine Speeds

The number of engine speeds is the number of different RPM settings at which the

simulation will be conducted. For this study, 17 engine speeds was selected based on

an initial speed of 500 RPM, with speed increments of 250 RPM up to a maximum

of 4500 RPM, or speed for graphics output.

Maximum Number of Revolutions at Each Speed

The software simulates each engine revolution by modelling the engine behaviour

mathematically at a large number of points throughout each engine revolution. As

the number of completed revolutions increases, the output power will approach a

steady value. Experiments have shown that for most engines, an acceptably steady

value is reached after 30 revolutions. The approach recommended by the MOTA



user manual is to enter a large number of revolutions, for example 100, because the

software has a built in mechanism for determining whether the program has reached

the steady value. When it does so, it will move on to the next engine speed

simulation.

Figure 28: Inlet Valve Detail Data Box

Inlet Reed Valve Details

Reed Block

In the inlet reed valve section, the data required was physically measured when the

engine was dismantled. The measured dimensions of the reed block can found in

Appendix D, and the input parameters are shown in Figure 28.

Reed Petal

The reed petal controls the reed block port. The reed petal is made of spring steel that

has a density of 7850 kg/m3 and a Young's Modulus of 207 GPa. The type of reed



petal in this engine is ‘single petal’, which does not have an outer petal with a length

less than the inner petal (compound petal).

The restricted maximum tip deflection refers to the maximum amount of distance the

reed petal can open until it is restricted by the stop plate. Figure 29 shows the plan

view of the reed petal and the stop plate. The maximum tip deflection was measured

to be 5mm when the engine was dismantled.

Figure 29: Image of the Reed Petal and Stop Plate

Uniform Section Reed Petal Type

The width, thickness and unclamped length of the reed petal were measured when

the engine was dismantled. The measurements can be seen in Appendix D.

Reed Petal

Stop Plate



Figure 30: Transfer Port Data Box

Transfer Port

Port Attitude Angle

There are two port attitude angles required as input parameters for the MOTA

software; Axial attitude angle and Radial attitude angle. The term axial attitude

angle refers to the port roof angle, and Radial attitude angle refers to the way the

vertical port walls are shaped. The measurements of both the axial and radial angles

are 15 and 35 degrees, and Figures 31 and 32 show how both these angles are

measured.

Figure 31: The Axial Attitude Angle



Figure 32: The Radial Attitude Angle

Port Timings

Almost all two-stroke engines contain at least one piston-controlled port, and the

accuracy of the port input data for the program can affect the accuracy of the

predicted engine performance. The physical measurements of the port timing were

taken as a length from the piston’s top dead centre in units of millimetres. However,

the units had to be converted into degrees below top dead centre for entry into the

program. Basic geometry was used for the conversion.

Profiled

A port is classified as profiled only if the port shape is not rectangular, which in the

case of this engine, the port shapes are rectangular. Therefore ‘No’ was chosen under

this column, and the un-profiled port’s dimensions were entered into the required

data box.



Figure 33: Exhaust Port Data Box

The exhaust port details were the next step in the modelling exercise, and these were

entered into the exhaust port data box (Figure 33).

Exhaust Port

The parameters in this data box were quite similar to the Transfer Port data box

(Figure 30), except for the Variable Opening Angle parameter. The remainder of the

parameters can be found in Appendix D.

Variable Opening Angle

This parameter is for engines with variable exhaust port timing. The two-stroke

outboard engine used in this project does not have variable exhaust port timing at

different engine speeds; hence ‘No’ was marked in this column.

Inlet and Transfer 1 Duct

Below is a description of the data entry requirements for these data boxes. The

required input parameters describe the physical attributes of the inlet and transfer

ducts. The entered values can be seen in Figures 35 and 36.



Bell Mouth Entry

This input parameter describes the entry of the inlet duct, i.e., flared or wide entrance

for the intake of air. When the engine was dismantled it was observed that there was

no bell mouth entry, rather, the entry was of a uniform diameter. Figure 34 shows

what a bell mouth entry of an inlet duct would look like.

Figure 34: Diagram of a Typical Inlet Duct with Reed Valve

Number of Sections

The MOTA software requires a description of the inlet duct, and Figure 34 shows

how this is achieved. The simple engine used in this study had an inlet duct

consisting of only two sections.

Inlet Reed Valve Section

The input parameters for this section were physical measurements taken during the

dismantling of engine. They have been presented in an earlier section and can be

seen in Appendix D.



Smooth Exit

A smooth exit refers to the outlet area of the section of the inlet duct. If the outlet

area is the same as the inlet area of the inlet duct, then it is defined as a smooth exit.

In the case of this engine, the exit area was different to the inlet area.

Figure 35: Inlet Duct Data Box

Figure 36: Transfer 1 Duct Data Box



Exhaust Pipe and Box Muffler

The data entry requirements for this data box can be seen in Figure 37. Entry Bell Mouth

The entry bell mouth option required for this data box has the same meaning as the

entry bell mouth option in Inlet and Transfer 1 Duct section.

Exhaust Section in Cylinder Barrel and Section Detail

The MOTA software requires the input of the diameter of the exhaust duct at its

entry and exit to and from the cylinder. Other detail such as the diameter of the

section at the cylinder barrel flange, and the length of the section between the flange

and piston face were also entered.

Figure 37: Exhaust Pipe and Box Muffler Data Box



Muffler Volume

The muffler in this engine comprises several irregular shaped sections, therefore, the

volume of each section was determined and then all sections summed to determine

the total volume of the muffler.

Figure 38: Exhaust System of the Outboard Engine

Volume Calculation

Muffler (part 1) = 45 mm x 70 mm x 20 mm

= 63000 mm3

Muffler (part 2) = 38 mm x 15 mm x 13 mm

= 7410 mm3

Muffler Total Volume = Muffler (1) + Muffler (2)

= 70410 mm3

The volume was then converted to cubic centimetres (cc) by dividing by 1000 to

arrive at a final volume of 70cc.

Muffler (1)

Tailpipe

Muffler (2)



Tailpipe

Figure 38 shows the position of the tailpipe, which is the final portion of the exhaust

system. The tailpipe has two functions: firstly, it reduces exhaust noise, and

secondly, it will also determine how efficiently the backpressure from the engine

exhaust is dissipated. The more efficiently the engine releases backpressure, the

more fuel-efficient and the more powerful it will be. The tailpipe length and

diameter were measured when the engine was dismantled.

3.11 Statistical Analysis

The software SPSS© for Windows (Release 11.5.0) was used to conduct all of the

Principal Components Analyses, the results of which are presented in the appropriate

chapters.


Chapter 4 – Results 98

CCHHAAPPTTEERR 44

Results

The following results are an extensive summary of the work conducted during the

entire project. The means and standard deviations of the emission rates of PAHs and

VOCs are presented for both lubricants and for both fresh and sea water. The results

of the four-stroke engine tests are presented in the same manner. These emission

rates are expressed in terms of micrograms per kilowatt hour (μg/kW.hr) in order to

relate the results to the amount of pollutant that is released and remains in the water

as an engine of this type of design passes. Because the experiments were conducted

in a tank, the results could not be presented as a concentration of the test tank water.

Therefore, engine power curves were used to convert the analytical results to the

emission rates as described in the experimental procedures section. The emission

rates are used in later Chapters where dilution and dispersion estimates are made.

Power and torque curves were not accessible for the two-stroke engine, so engine

modelling was conducted using the MOTA version 6 software package. This

software is a personal computer based two-stroke engine simulation program, which

requires the dimensions of the engine components as input parameters and in turn

provides the expected operating out put parameters. The measured RPM and fuel

consumption rates for the engine were used to calibrate the program, and this was

conducted by (Woo, 2002). The results are expressed in this form so they can be

used for modelling at a later date. Also presented are the concentrations of these

compounds in the raw fuel and oils.



4.1 Fuel Consumption Tests

The fuel consumption (FC) tests were conducted both in the laboratory and in the

field. The tests were also conducted for both types of engine; however, they were

only conducted in the laboratory for the four-stroke engine. Further, as well as the

rates of fuel consumption at the various throttle settings, the RPM readings were also

recorded during each of the tests. The aim of this experiment was to compare the

rate of fuel consumption and RPM of a marine two-stroke outboard engine both in a

tank and in the field; and to compare the rate of fuel consumption and RPM of a

marine two-stroke outboard engine when using the different lubricating oils. The

comparison was expanded to include an investigation between both two and four

stroke engines.

4.1.1 Two-Stroke Engine FC Tests – Laboratory

As previously stated, three tests were conducted at each of the throttle settings.

Table 6 shows the mean and the standard deviation of the fuel consumption rates

when both lubricating oils were used. It can be seen that there was virtually no

difference in the fuel consumption rate when either of the oils were used.

Table 6: Two-Stroke Engine Fuel Consumption Tests Conducted in the Laboratory

Fuel Use mL/s Throttle Setting Laboratory Tank Tests 20% 40% 60% 80% 100%

Fuchs Mineral Oil Average 0.057 0.112 0.165 0.280 0.395 Fuchs Mineral Oil Std Deviation 0.002 0.001 0.002 0.003 0.008

Fuchs EAL Average 0.057 0.114 0.168 0.280 0.395

Fuchs EAL Std Dev 0.000 0.003 0.002 0.009 0.013

At the same time the fuel consumption tests were being conducted, the engines

RPMs were also recorded. Table 7 shows the mean and standard deviation of the

engine RPMs when both lubricating oils were used. There was a noticeable decrease

in the engine revolutions when the EAL was used.



Table 7: Two-Stroke Engine RPM Tests Conducted in the Laboratory

RPM Throttle Setting Laboratory Tank Tests 20% 40% 60% 80% 100%

Fuchs Mineral Oil Average 863 1990 2657 3350 4023 Fuchs Mineral Oil Std Deviation 25 10 12 95 76

Fuchs EAL Average 757 1950 2510 3317 4263

Fuchs EAL Std Dev 15 35 36 25 107

4.1.2 Two-Stroke Engine FC Tests – Field

As above, three tests were conducted, using a small wooden boat (see Figure 16), to

determine the rate of fuel consumption of the engine when used in the field. Table 8

shows the mean and standard deviation of the test results when both lubricants were

used. Little difference was observed in the results, except for the result at 20%

throttle setting. It can be seen that at this setting the rate of fuel consumption was

significantly lower when the mineral oil was used. There is no simple explanation

for this, since the same result did not occur for the laboratory tests, yet the small

standard deviation suggests that the data acquisition was conducted appropriately.

Table 8: Two-Stroke Engine Fuel Consumption Tests Conducted in the Field

Fuel Use mL/s Throttle setting Field Testing 20% 40% 60% 80% 100%

Fuchs Mineral Oil Average 0.030 0.104 0.182 0.311 0.400 Fuchs Mineral Oil Std Deviation 0.008 0.038 0.024 0.037 0.025

Fuchs EAL Average 0.051 0.119 0.189 0.299 0.406 Fuchs EAL Std Dev 0.008 0.016 0.008 0.011 0.026

As with the laboratory tests, the RPM readings were recorded at the time of the fuel

consumption tests. Table 9 shows these results, and it can be seen that there were

smaller differences in the RPM readings when using either of the lubricants.

Table 9: Two-Stroke Engine RPM Readings Conducted in the Field

RPM Throttle Setting Field Testing 20% 40% 60% 80% 100%

Fuchs Mineral Oil Average 797 2137 3100 3947 4473 Fuchs Mineral Oil Std Deviation 80 76 46 130 35

Fuchs EAL Average 743 2087 3047 3913 4500

Fuchs EAL Std Dev 25 35 51 67 26



4.1.3 Four-Stroke Engine FC Tests – Laboratory

The fuel consumption tests were also conducted for the four-stroke engine, however,

only in the laboratory; Table 10 shows the results of these tests. It should also be

pointed out that only one lubricant was used during all of the four-stroke engine tests

because, unlike the two-stroke engine, the lubrication system of this engine is

isolated from the combustion process. Therefore it is not necessary to compare the

results when using different lubricants.

Table 10: Fuel Consumption Rates at the Throttle Various Settings for the Four-Stroke Engine

Fuel Use mL/s Throttle Setting Laboratory Tank Tests 20% 40% 60% 80% 100%

Standard Mineral Oil Average 0.055 0.563 0.721 0.833 0.945 Standard Mineral Oil Std Deviation 0.002 0.040 0.012 0.056 0.013

As with the two-stroke engine, the RPM readings were also recorded when the fuel

consumption tests were conducted in the laboratory using the four-stroke engine.

Table 11 shows the mean and standard deviation of the engine RPM during the tests.

Table 11: Engine RPM at the Various Throttle Settings for the Four-Stroke Engine

RPM Throttle Setting Laboratory Tank Tests 20% 40% 60% 80% 100%

Standard Mineral Oil Average 705.0 3032.0 3748.5 4017.5 4254.5 Standard Mineral Oil Std Deviation 15.8 120.5 93.9 113.3 81.0

4.2 Preliminary Pollutant Investigation Results

The preliminary study was broad and investigated the presence of more than seventy

compounds. As previously mentioned, PAHs and VOCs were the compounds

identified in this part of the study, and Tables 12 and 13 show a summary of the

results. The full results of the study can be seen in Appendix A. It needs to be borne

in mind that this investigation was only for the identification of pollutants. The

concentrations provided cannot be accepted with any confidence because only one

sample of water was analysed (Kelly et al., 2001a, Kelly et al., 2001b).



Table 12: Summary of the Preliminary PAH Results

PAH Compounds Mineral Oil

(μg L-1)

EAL

(μg L-1)

Acenaphthylene <1.0 1.4

Naphthalene 2.6 83

Phenanthrene <1.0 1.4

Table 12 shows that the concentrations of the three PAH pollutants were higher when

the EAL was used during the preliminary test.

Table 13: Summary of the Preliminary VOC Results

VOC Compounds Mineral Oil

(μg L-1)

EAL

(μg L-1)

Benzene 1100 1200

Toluene 2300 2600

Ethylbenzene 330 380

m & p – Xylenes 1500 1700

o – Xylene 700 780

1,2,4 – Trimethylbenzene 810 490

4 – Isopropyltoluene 4400 2900

n – Butylbenzene 300 <250

Table 13 shows that there was little difference in the concentrations of the BTEX

group of VOC compounds when either of the lubricants was used, however, the

differences were much more pronounced for the other compounds.

4.3 Raw Fuel and Oil Results

Table 14 shows the levels of each of the PAH compounds in the fuel and oil mixtures

for the two lubricating oils used in the engine tests. Also shown is the concentration

in the oil itself, however, this can be misleading since only 20mL of oil is mixed with

1 litre of fuel. The fuel is the major contributor, in most instances, to the content of

these compounds in the fuel/oil mixtures.



Table 14: PAH Pollutants in the Raw Fuel and Oils, and in the Fuel and Oil Mixtures

COMPOUND Fuel (ug/L) Mineral Oil (ug/L) EAL (ug/L)

Fuel / Mineral Oil Mixture

(ug/L)

Fuel / EAL Mixture (ug/L)

Naphthalene 1682.65 28644.50 1305.50 2255.54 1708.75Acenaphthylene 30.63 40.00 50.50 31.43 31.64Acenaphthene 28.47 89.00 65.50 30.25 29.78

Flourene 35.29 28.00 14.00 35.85 35.57Phenanthrene 13.04 5.00 3.50 13.14 13.10

Anthracene 9.92 8.00 5.00 10.08 10.02Flouranthene 4.29 396.00 159.00 12.21 7.48

Pyrene 6.18 780.50 1004.00 21.79 26.26Chrysene 0.13 3687.00 1230.50 73.87 24.74

1, 2 - Benzanthracene 0.00 1566.50 680.50 31.33 13.61Benzo(k)fluoranthrene 70.33 1498.50 1010.00 100.30 90.53

Benzo(a)pyrene 263.33 1768.00 1067.50 298.69 301.25Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 525.63 3579.00 828.50 597.21 542.20

1.12 - Benzoperylene 0.00 1047.50 224.50 20.95 4.49

It can be seen that the concentrations of the pollutants in the raw EAL, in most

instances, are lower than the equivalent mineral oil. The exceptions are pyrene and

acenaphthylene. One concern that arises from this investigation is that the analysis

has shown that the composition of the raw lubricants is primarily made up of the

heavier PAH compounds, although the naphthalene concentrations were also

relatively high. These were earlier identified as the compounds most likely to be

carcinogenic to humans, and as such, care needs to be taken when handling them.

Also, care needs to be taken to ensure that when mixing the fuel and oils, spills into

the environment do not occur.

It can also be seen that in the raw fuel itself, naphthalene is by far the most abundant

of the PAHs. When the fuel and oils are mixed in the appropriate proportions, the

relatively high concentrations of the heavier PAHs in the oils are diluted and

naphthalene becomes the PAH in the highest concentration.



The results for the analysis of the VOCs are presented in a similar manner to those of

the PAHs. Table 15 shows that the lubricating oils contribute almost no VOCs to the

raw fuel and oil mixtures; the fuel itself appears to be the primary contributor to

these compounds. Interestingly, the EAL showed measurable levels of some of the

VOCs. Also note that the units for the concentrations are in terms of milligrams per

litre for the VOCs, whereas, they were in micrograms per litre for the PAHs.

Table 15: VOC Pollutants in the Raw Fuel and Oils, and in the Fuel and Oil Mixtures

COMPOUND Fuel (mg/L) Mineral Oil (mg/L) EAL (mg/L)

Fuel / Mineral Oil Mixture

(mg/L)

Fuel / EAL Mixture (mg/L)

Benzene 10624.00 <5 <5 10624.00 10624.00Toluene 47840.00 300.00 650.00 47840.00 47840.00

Ethyl benzene 6786.00 <5 1500.00 6786.00 6787.00o, m-xylenes 18774.00 <5 4300.00 18774.00 18776.00

p-xylene 12266.00 <5 2100.00 12266.00 12266.00C3 benzenes 26023.00 <50 <50 26023.00 26023.00C4 benzenes 8479.00 <50 <50 8479.00 8479.00Naphthalene 154.00 14750.00 <5 160.00 154.00

Alkyl naphthalenes 338.00 <50 <50 338.00 338.00

While the concentrations of some of the VOCs in the EAL appear to be significantly

higher than in the mineral oil, when mixed in the appropriate proportions with the

fuel, the differences are negligible.

4.4 Two - Stroke Engine Laboratory Test Results – PAHs

Table 16 shows the results of the PAH pollutants analysis when the mineral lubricant

was used. The results are expressed as an emission rate for each of the compounds;

the mean and standard deviation are shown. The compounds naphthalene,

phenanthrene, and 1, 2 – benzanthracene were emitted at the highest rates. Overall,

there are no definite trends in the emission rates with varying throttle setting, except

for the emission rate of naphthalene. This compound shows a linear increase in

emission rate with increasing throttle setting. Also note the magnitude of the

standard deviations of the data. The data was likely to be affected by variables such



as water temperature and air temperature, both of which were beyond the control of

the experimental procedure. It has been observed by other researchers involved in

engine emission experiments, that the variability of the data is often large (pers. com.

Dr Ayoko).

Table 16: PAH Pollutants Analysis when the Mineral Lubricant was used in the Laboratory Tests

Another observation is that at overall there were more PAHs emitted at the higher

throttle settings. For instance, anthracene, indeno(1,2,3-cd)pyrene, 1.2:5.6-

dibenzanthracene and 1.12-benzoperylene were not emitted until 80% throttle was

reached. Other compounds such as fluorene and chrysene were not emitted at all.

Others again, such as acenaphthylene and acenaphthene were emitted at higher

concentrations when at the low throttle settings. However, the overall trend was that

more pollutants were emitted at higher throttle settings.

The obvious reason would be simply that the engine uses more fuel at the higher

throttle settings; yet, this simple assumption might be incorrect. The compounds

phenanthrene and benzo(a)pyrene were emitted at both low and high throttle settings,

while at 40% and 60% throttle settings they were not emitted at all. 1, 2

COMPOUNDMean @ 20%

Throttle (ug/kW.hr)

Std Dev @ 20% Throttle (ug/kW.hr)

Mean @ 40% Throttle

(ug/kW.hr)


Mean @ 60% Throttle

(ug/kW.hr)


Mean @ 80% Throttle

(ug/kW.hr)


Mean @ 100% Throttle

(ug/kW.hr)

Std Dev @ 100% Throttle

(ug/kW.hr)

Naphthalene 63.23 57.48 147.54 64.36 231.10 56.25 326.75 62.61 421.62 53.44

Acenaphthylene 2.12 3.66 3.17 5.48 0.00 0.00 0.00 0.00 0.13 0.23

Acenaphthene 34.83 60.33 2.31 4.01 2.05 3.55 11.86 10.30 12.86 17.15

Flourene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Phenanthrene 487.66 844.66 0.00 0.00 0.00 0.00 93.19 161.41 176.65 152.60

Anthracene 0.00 0.00 0.00 0.00 0.00 0.00 11.72 18.56 16.86 26.34

Flouranthene 1.80 3.11 12.10 15.60 8.34 5.47 15.12 26.18 8.14 12.45

Pyrene 0.00 0.00 7.99 12.86 6.55 6.01 9.16 14.83 1.01 1.76

Chrysene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

1, 2 - Benzanthracene 119.03 127.25 48.44 66.91 231.63 376.17 223.06 277.38 100.46 154.44

Benzo(k)fluoranthrene 32.37 56.07 16.01 27.74 12.96 22.45 30.91 36.18 11.56 20.02

Benzo(a)pyrene 14.79 25.62 0.00 0.00 0.00 0.00 80.47 57.49 6.46 11.18

Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00 0.00 0.00 0.00 0.00 0.00 6.96 12.06 4.17 7.23

1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00 8.67 15.02 8.06 13.96



benzanthracene was emitted at the highest concentrations at 60% and 80% throttle

settings. There is no one trend to explain the emission rates of the PAH pollutants

when using the mineral lubricant in fresh water. One could make the general

assumption that when at high throttle settings more PAHs will be emitted.

Table 17 shows the results of the PAH pollutants analysis when the environmentally

adapted lubricant was used. The results are expressed as an emission rate for each of

the compounds; the mean and standard deviation are shown. As with the mineral

lubricant, the compounds naphthalene, phenanthrene, and 1, 2 – benzanthracene were

emitted at the highest rates. Again there are no definite trends in the emission rates

with varying throttle setting. Also, as with the previous results, the standard

deviations sometimes exceeded the mean emission rates.

Table 17: PAH Pollutants Analysis when the EAL was used in the Laboratory Tests

Unlike Table 16, Table 17 shows that there is a more evenly distributed rate of

emissions of the PAH pollutants across the range of throttle settings. A more

detailed comparison will be conducted in later Chapters between the emission rates

of all of the pollutants when using the different lubricants. Anthracene was emitted

at its highest rate at 20% throttle setting, while phenanthrene had its highest rate at

COMPOUNDMean @ 20%

Throttle (ug/kW.hr)


Mean @ 40% Throttle

(ug/kW.hr)


Mean @ 60% Throttle

(ug/kW.hr)


Mean @ 80% Throttle

(ug/kW.hr)



(ug/kW.hr)


(ug/kW.hr)

Naphthalene 20.05 34.72 126.68 219.41 118.39 193.67 6.61 11.45 264.00 245.74

Acenaphthylene 11.14 19.30 1.74 3.01 2.87 2.89 0.15 0.26 1.84 2.03

Acenaphthene 21.42 11.08 10.46 18.11 7.71 8.47 4.09 7.08 14.46 17.19

Flourene 2.72 4.72 6.83 11.83 6.81 7.84 2.46 4.26 10.29 11.97

Phenanthrene 2.80 4.85 202.75 349.28 119.79 172.85 111.58 193.27 0.79 0.72

Anthracene 648.84 1115.31 1.28 2.21 0.61 0.61 1.14 1.04 2.03 3.51

Flouranthene 30.69 48.33 0.00 0.00 0.70 1.21 1.00 1.73 0.00 0.00

Pyrene 19.96 34.57 6.11 10.58 3.45 5.97 34.51 59.78 4.80 5.89

Chrysene 0.00 0.00 0.41 0.70 3.82 1.82 0.22 0.38 27.95 45.71

1, 2 - Benzanthracene 46.17 79.97 45.04 78.01 250.92 253.37 0.00 0.00 14.92 25.84


Benzo(a)pyrene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 31.54 31.79


1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00



40% throttle and 1, 2 benzanthracene at 60% throttle. Others such as

acenaphthylene, acenaphthene and fluorene were emitted at rates that were generally

constant across the range of throttle settings.

4.5 Two - Stroke Engine Laboratory Test Results – VOCs

The emission rates of the VOC compounds were significantly higher than those of

the PAHs. Tables 18 and 19 show the VOC emission rates when both of the

lubricants were used. The values for toluene and C3 benzenes were very high, while

the values for alkyl naphthalenes were much lower; this trend occurred for both

lubricants. However, some of the individual values were significantly higher when

the EAL was used instead of the equivalent mineral oil.

Table 18: VOC Pollutants Analysis when the Mineral Lubricant was used in the Laboratory Tests

In all instances, Table 16 shows the emission rates of the pollutants were lowest at

20% throttle setting, and with the exception of naphthalene and C4 benzene, highest

at 100% throttle setting. Naphthalene was emitted the most at 80% throttle while C4

benzene at 40% throttle setting. Interestingly, after 100% throttle, 40% throttle

setting was the setting at which the next highest emission rates occurred. This would

indicated that at this setting, the engine, in terms of pollution, is running at its most

inefficient given its much lower rate of fuel consumption at this setting. This is

COMPOUNDMean @ 20%

Throttle (ug/kW.hr)


Mean @ 40% Throttle

(ug/kW.hr)


Mean @ 60% Throttle

(ug/kW.hr)


Mean @ 80% Throttle

(ug/kW.hr)



(ug/kW.hr)


(ug/kW.hr)

Benzene 1119.09 1004.93 3051.33 305.42 2446.32 575.37 2247.12 344.63 3161.68 144.89

Toluene 3111.13 19.30 10195.38 1666.94 8422.16 1977.71 7799.94 0.26 11102.02 878.13

Ethyl benzene 333.28 11.08 1427.08 202.02 1298.40 362.74 1127.82 7.08 1524.00 338.36

o, m-xylenes 1022.90 4.72 4125.61 482.29 3707.70 1081.74 3275.96 4.26 4477.84 1065.75

p-xylene 759.65 4.85 2737.70 447.54 2444.35 621.82 2201.80 193.27 3142.24 565.34

C3 benzenes 1846.00 1115.31 10840.30 1478.97 10078.39 3046.94 8372.65 1.04 11109.19 3918.66

C4 benzenes 1137.59 48.33 7139.28 678.81 7003.40 2522.21 5499.25 1.73 6705.16 3358.30

Naphthalene 0.00 34.57 92.34 13.77 94.31 27.80 135.92 59.78 129.96 26.67

Alkyl naphthalenes 0.00 0.00 0.00 0.00 0.00 0.00 243.99 0.38 291.16 83.46



important to note since the average boat user spends 25% of their trip time at 40%

throttle.

Table 19: VOC Pollutants Analysis when the EAL was used in the Laboratory Tank Tests

As with Table 18, Table 19 shows that the lowest rates of emission occurred at 20%

throttle, and with the exception of C3 and C4 benzenes, highest at 100% throttle. As

with the previous Table, 40% throttle had the next highest emission rates, which

were very close in magnitude to those of the 100% throttle setting.

4.6 Two - Stroke Engine Field Test Results – PAHs

The sea water results showed similar trends to the fresh water results. The results in

Table 20 show that naphthalene is the compound that is emitted consistently at a high

rate, except for the benzo(a)pyrene figure at 20% throttle setting. Another result of

interest is that 1,2 benzanthracene and benzo(k)fluoranthene were emitted significant

levels only at 60% throttle, they were not emitted at all at either 20% or 100%

throttle settings.

COMPOUNDMean @ 20%

Throttle (ug/kW.hr)


Mean @ 40% Throttle

(ug/kW.hr)


Mean @ 60% Throttle

(ug/kW.hr)


Mean @ 80% Throttle

(ug/kW.hr)



(ug/kW.hr)


(ug/kW.hr)

Benzene 2271.97 1339.49 3496.30 1484.11 3232.19 391.25 2835.61 868.73 3954.27 1096.10

Toluene 6232.60 3981.23 11419.99 6854.96 10431.27 1715.39 9031.72 2685.43 13418.26 5429.07

Ethyl benzene 746.13 508.91 1534.02 1124.99 1321.94 203.14 1040.38 276.87 1811.47 435.95

o, m-xylenes 1820.55 1214.19 4442.29 3457.31 3661.83 568.89 2909.30 723.40 5443.81 524.64

p-xylene 1422.66 916.70 3233.38 2438.06 2658.80 409.81 2251.31 549.45 3666.86 992.28

C3 benzenes 5079.33 4404.45 14028.41 13606.60 9651.62 1625.41 6961.37 1214.82 11691.54 5083.84

C4 benzenes 1999.79 1895.03 9221.16 9289.34 5761.37 913.02 3889.26 292.85 6494.22 3817.38

Naphthalene 29.23 50.63 144.50 134.38 91.72 16.16 89.89 18.86 188.00 40.15




Table 20: PAH Pollutants Analysis when the Mineral Lubricant was used for the Field Tests

When the EAL was used for the field tests, Table 21 shows that again naphthalene

was emitted at the highest rates, and consistently across the throttle settings. In this

case however, the compounds phenanthrene, fluoranthene, and pyrene were emitted

at significant concentrations at low throttle settings, and aside from naphthalene, all

other compounds were emitted at low rates across all settings.

Table 21: PAH Pollutants Analysis when the EAL was used for the Field Tests

COMPOUNDMean @ 20%

Throttle (ug/kW.hr)


Mean @ 60% Throttle

(ug/kW.hr)



(ug/kW.hr)


(ug/kW.hr)

Naphthalene 197.45 174.83 535.85 215.08 569.55 114.43

Acenaphthylene 24.14 41.81 0.00 0.00 6.83 11.82

Acenaphthene 0.00 0.00 6.32 10.95 6.50 6.66

Flourene 0.00 0.00 0.00 0.00 0.00 0.00

Phenanthrene/Anthracene 28.64 49.61 0.00 0.00 22.52 21.97

Flouranthene 0.00 0.00 44.66 41.44 20.45 20.22

Pyrene 0.00 0.00 0.00 0.00 8.30 14.37

Chrysene 0.00 0.00 0.00 0.00 0.00 0.00

1, 2 - Benzanthracene 0.00 0.00 137.03 118.67 0.00 0.00

Benzo(k)fluoranthrene 0.00 0.00 162.76 281.92 0.00 0.00

Benzo(a)pyrene 812.96 850.91 0.00 0.00 8.72 15.10

Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00 0.00 0.00 0.00 0.00 0.00

1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00

COMPOUNDMean @ 20%

Throttle (ug/kW.hr)


Mean @ 60% Throttle

(ug/kW.hr)



(ug/kW.hr)


(ug/kW.hr)

Naphthalene 469.57 184.36 428.46 140.36 691.72 203.33

Acenaphthylene 1.58 2.73 1.69 2.93 0.00 0.00

Acenaphthene 28.77 49.83 6.30 2.91 7.04 6.19

Flourene 0.00 0.00 2.45 0.85 26.25 29.65

Phenanthrene/Anthracene 153.93 266.61 -0.75 1.30 0.00 0.00

Flouranthene 130.00 225.17 2.99 5.18 0.00 0.00

Pyrene 699.76 814.17 27.56 49.02 33.36 48.64

Chrysene 0.00 0.00 0.00 0.00 0.00 0.00

1, 2 - Benzanthracene 0.00 0.00 0.00 0.00 0.00 0.00


Benzo(a)pyrene 0.00 0.00 0.00 0.00 14.87 25.76


1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00



4.7 Four - Stroke Engine Laboratory Results – PAHs

Table 22 shows that the emission rates of naphthalene are almost constant across the

range of throttle settings, while acenaphthylene decreases in emission rate with

increasing throttle setting. There is no trend in the emission rates of the other

compounds, however, the most obvious feature of this table is that almost all of the

pollutants are in the lighter (non-carcinogenic) range. Benzo(k)fluoranthrene at 80%

and 100% throttle setting and indeno(1,2,3 – C,D)pyrene, 1,2: 5,6 –

dibenzanthracene and 1,12 – benzoperylene at 100% throttle setting are the only

“heavy” PAHs emitted.

Table 22: PAH Pollutants Analysis for the Four-Stroke Engine Tests Conducted in the Laboratory

4.8 Four - Stroke Engine Laboratory Results – VOCs

The mean emission rates of the VOCs and their standard deviations are shown in

Table 23. It can also be seen that when the engine is run at only 20% throttle, there

are very few VOCs emitted, with benzene and toluene being the only compounds

present in the water samples.

COMPOUNDMean @ 20%

Throttle (ug/kW.hr)


Mean @ 40% Throttle

(ug/kW.hr)


Mean @ 60% Throttle

(ug/kW.hr)


Mean @ 80% Throttle

(ug/kW.hr)



(ug/kW.hr)


(ug/kW.hr)

Naphthalene 26.69 19.57 27.27 8.94 21.08 2.38 19.07 7.28 21.05 1.42

Acenaphthylene 19.66 34.06 4.52 6.87 3.01 4.61 1.95 3.37 1.74 2.02

Acenaphthene 26.45 32.25 3.53 0.87 2.72 1.10 1.91 1.67 2.68 0.79

Flourene 63.37 38.54 17.34 12.02 12.82 12.33 8.12 5.12 8.91 6.11

Phenanthrene 23.71 41.07 17.62 5.97 9.26 1.64 9.48 3.25 11.28 1.54

Anthracene 0.00 0.00 18.34 5.81 11.53 4.37 12.20 4.37 11.20 3.01

Flouranthene 83.95 145.41 12.49 21.64 0.00 0.00 17.50 15.48 6.73 11.66

Pyrene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Chrysene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

1, 2 - Benzanthracene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00


Benzo(a)pyrene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00


1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 88.62 153.49



Table 23: VOC Pollutants Analysis for the Four-Stroke Engine Tests Conducted in the Laboratory

Another interesting observation from Table 23 is that it would appear that 40%

throttle is the most inefficient of all the settings with respect to the emissions of

VOCs from a four-stroke outboard engine. It can be seen that the rates of emission

of the VOCs was highest for all compounds at this setting. As with the rest of the

data sets, the standard deviations were large when compared to the mean

concentrations.

4.9 Two-Stroke Engine Performance Modelling

As described in the methodology section of the thesis, measured engine parameters

such as rate of fuel consumption and RPM reading were taken, and they inturn were

used to calibrate the modelling software. Figure 39 shows the calibrated output

power curve for the two-stroke engine at intervals of 250RPM. It can be seen that it

resembles a characteristic power curve that one would expect from any engine. The

power curve for the four-stroke engine was supplied by the manufacturer, Honda

Marine Pty Ltd, and can be seen in Appendix E.

COMPOUNDMean @ 20%

Throttle (ug/kW.hr)


Mean @ 40% Throttle

(ug/kW.hr)


Mean @ 60% Throttle

(ug/kW.hr)


Mean @ 80% Throttle

(ug/kW.hr)



(ug/kW.hr)


(ug/kW.hr)

Benzene 99.94 71.59 609.89 476.22 308.72 200.24 335.09 199.81 396.57 210.87

Toluene 173.59 96.96 1394.91 800.14 617.04 546.88 673.59 242.50 570.00 368.74

Ethyl benzene 0.00 0.00 182.25 112.03 75.45 82.85 79.69 33.94 67.23 51.19

o, m-xylenes 0.00 0.00 70.76 39.31 28.96 31.46 31.12 13.91 26.10 22.66

p-xylene 0.00 0.00 36.15 18.97 15.50 18.16 18.59 7.58 14.66 12.71

C3 benzenes 0.00 0.00 945.38 438.52 430.26 396.25 471.32 203.54 361.53 314.02

C4 benzenes 0.00 0.00 458.18 183.89 199.83 192.55 291.44 126.36 195.96 169.83

Naphthalene 0.00 0.00 149.16 31.46 95.43 66.61 146.48 48.47 97.62 75.80




Modelled Power Curve using MOTA

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500

RPM

Pow

er (k

W)

Figure 39: the Power Curve Developed by the MOTA Software after the Modelling Exercise was Undertaken

When calibrating the model, consideration was given to not only the previously

mentioned measured parameters, but also to the rated power of the engine. At full

throttle the engine is expected to have a maximum power output of approximately

1.9kW. When the modelling was being conducted this figure, in conjunction with

the other data, was kept in mind and used as a guide for the model results. The

results were such that, in order to achieve a maximum power output that was close to

the rated power of the engine, there was an error associated with the rate of fuel

consumption that the model produced, when compared to the measured rate of fuel

consumption of the actual engine. This however was expected because the engine

was run in a tank and subject to a backflow of water impacting upon the propeller.

This resulted in the engine sometimes being under a greater load than it would



typically be when on the back of a boat. Further, the reverse also occurred where the

engine was under less of a load. This is evident by the results shown in Figure 40.

Field Testing vs Software Data(Fuel Consumption)

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

5.00

10.00

15.00

20.00

25.00

30.00

20 40 60 80 100

Throttle Setting (%)

Erro

r (%

)

FUCHS Bio-degradable FUCHS MineralEAL

Figure 40: Differences between the Results of the Actual and Modelled Fuel Consumption Rates for the Two-Stroke Engine

Table 24: Final Power Output Values used to Perform the Calculations for each of the Throttle

Settings and Both Lubricants

Lubricant TypeThrottle Setting

Engine Speed

Modelled Power

Output of Test Engine

Measured Fuel

consumption

Brake Specific Fuel Consumption

(b.s.f.c)

b.s.f.c % Error

MOTA/Test

Name % RPM kW mL/s kg/kW.h %EAL 100 4263 1.846 0.395 0.601 -17.78

Mineral 100 4023 1.809 0.395 0.613 -19.45EAL 80 3317 1.494 0.28 0.526 -5.55

Mineral 80 3350 1.501 0.28 0.524 -5.11EAL 60 2510 1.138 0.168 0.415 19.40

Mineral 60 2657 1.166 0.165 0.397 24.59EAL 40 1950 0.797 0.114 0.402 21.44

Mineral 40 1990 0.803 0.112 0.391 24.65EAL 20 757 0.311 0.057 0.515 1.61

Mineral 20 863 0.325 0.057 0.492 6.32

EAL Mineral



Table 24 is a summary of the modelling output for the two-stroke engine. It can be

seen that the power output from the engine can be affect by the type of lubricant

used, and this was observed across all of the throttle settings. Interestingly, the

output power at all of the throttle settings, except for 100% throttle setting, was

higher when the mineral lubricant was used. The same observation is made for the

RPM readings. It can also be seen that the fuel consumption rate errors were least at

20% and 80% throttle settings and highest for 40% and 60% throttle settings.

4.9 General Discussion

The significance of this work is that an investigation into the pollutants that remain

within the water column after an outboard engine has been used has now been

completed. That aside, some other interesting findings arose from the study.

Firstly, Table 7 showed that when the EAL was used, the RPM readings taken were

lower at all throttle settings except 100%; yet there was no significant difference in

the rates of fuel consumption when either of the lubricants was used. Given that this

occurred, and that the RPM readings and the rates of fuel consumption were used to

calibrate the power output for the engine performance modelling, this had an impact

on the output power results. This result suggests that at the throttle settings of 20%,

40%, 60% and 80%, the engine is less efficient when the EAL is used. This could be

due to a number of reasons.

It is possible that the octane value of the fuel/oil mixture is lower when the EAL is

used. This would have the effect of producing less power and lower RPM at a fixed

throttle setting. Also, the viscosity of the fuel/oil mixture could be higher when the



EAL is used. This would reduce the lubricity of the mixture, thereby lowering the

RPM and power output for a given throttle setting.

At 100% throttle setting however, the RPM and subsequently the power output were

higher when the EAL was used. This would suggest that the octane value of the

fuel/oil mixture is not affected by the use of either of the lubricants. The viscosity

however, could still be the cause of the differences, in that; temperature plays a

significant role in this. The EAL could operate best at the higher temperatures of the

full throttle setting. Testing these hypotheses was not within the scope of this

project, and is therefore recommended for future work arising from this research.

The standard deviations of the data were at times very large, up to 100% higher or

lower than the mean values; a number of reasons are the likely cause of this. It was

noted earlier that temperature plays an important role in the solubility of PAHs in

water. While the test procedure was conducted in exactly the same manner for each

of the tests, it was not possible to replicate the water temperature. While not

measured for each of the tests, it is thought that the water temperature could fluctuate

by up to 2°C on any given day, and this inturn could affect the quantities and types of

pollutants remaining in the water.

Further, air temperature could also play a part in the large standard deviations. The

PAH pollutants in particular are produced during the process of combustion, and are

therefore reliant on the temperature and pressure within the cylinder of the engine.

The atmospheric air temperature and pressure can affect the temperature and pressure

within the cylinder, and therefore the types and quantities of pollutants produced.



Because most PAH pollutants are not produced commercially, there is little

information at hand as to what temperatures and pressures are required to produce

them. It would be advantageous to set up an engine with temperature and pressure

probes inserted into the cylinder head to attempt to correlate these variables with

certain PAHs that are produced. This would be interesting research for the wider

scientific community.

It is not expected that instrument error played a part in the large standard deviations.

The use of internal standards of a known concentration enabled the correction of the

raw data before calculations were conducted.

The emissions of the pollutants during the warm-up phase of the experiments were

not included into the overall assessments of the results. It is expected that the

duration of five minutes would play an insignificant part in the overall estimate of

the volume of pollutants, given that a typical boat user would be on the water for the

best part of the day. It is expected however, that the type and concentrations of the

pollutants would vary when the engine is cold. This inturn could have some bearing

on the type and concentrations of the pollutants at locations such as boat ramps and

marinas. This highlights the need for an investigation of the pollutant loads at sites

such as these.


Chapter 5 – Polycyclic Aromatic Hydrocarbons Analysis 117

CCHHAAPPTTEERR 55

Polycyclic Aromatic Hydrocarbons Analysis for the

Two-Stroke Engine

Revisiting and summarising part of the literature: PAHs are serious water pollutants

(Baird, 1999). However, if the total estimated amounts of PAHs that enter the

aquatic environment were evenly distributed throughout the world’s oceans and

freshwater bodies, their concentrations would be completely undetectable. Yet, they

are not evenly distributed. Most PAHs remain relatively near their point source, and

can be expected to decrease in concentration approximately logarithmically with

distance from the source. Thus, the majority of PAHs entering the aquatic

environment are localized in rivers, estuaries, and coastal marine waters (Neff,

1979). While it will be seen in this study that the emission rates are relatively low, in

needs to be borne in mind that the investigation has focused on only one engine.

Further, there are two molecular weight classes of PAHs that they are distinguished

on the basis of their physical, chemical, and biological properties. These are the

lower molecular weight 2 – 3 ring aromatics and the higher molecular weight 4 – 7

ring aromatics. The low molecular weight PAHs have been shown to display acute

toxicity to aquatic organisms, whereas the high molecular weight PAHs do not.

However, all of the 20 – 30 proven PAH carcinogens are in the high molecular

weight category (Neff, 1979). This investigation identifies both categories.

In the past, marine pollution by PAHs has been attributed to sources such as

creosote-treated timber from docks. This source was so serious in parts of Atlantic



Canada in the early 1980’s that the local lobster fisheries industry was closed down

because of the high PAH levels found in the crustaceans. Larger PAH molecules are

thought to have played a role in the devastation of the populations of beluga whales

in the St. Lawrence River, and they have also been linked to the production of liver

lesions and tumors in some fish (Baird, 1999). PAHs have been linked primarily

with anthropogenic sources such as waste water treatment and recreational vessels.

This chapter addresses some of the aims of this research, where a significant part of

the project was to make comparisons between the emissions when using different

lubricants, and comparisons between the emissions to both fresh and seawater for the

two-stroke outboard engine. The above summary identifies the need for research on

PAH emissions in these areas, and these are now conducted.

5.1 Mineral vs. EAL Laboratory Tests PAH Results

Following is a detailed comparison between the PAH results when using the two

types of lubricants in the laboratory tests. Table 25 below summarises the data for

this comparison.

Table 25: Emission Rates of the PAH Pollutants when using both Lubricants - Laboratory Tests

COMPOUND

Mean @ 20% Throttle

(ug/kW.hr) Mineral Oil

Mean @ 20% Throttle

(ug/kW.hr) EAL

Mean @ 40% Throttle


Mean @ 40% Throttle

(ug/kW.hr) EAL

Mean @ 60% Throttle


Mean @ 60% Throttle

(ug/kW.hr) EAL

Mean @ 80% Throttle


Mean @ 80% Throttle

(ug/kW.hr) EAL




(ug/kW.hr) EAL

Naphthalene 63.23 20.05 147.54 126.68 231.10 118.39 326.75 6.61 421.62 264.00

Acenaphthylene 2.12 11.14 3.17 1.74 0.00 2.87 0.00 0.15 0.13 1.84

Acenaphthene 34.83 21.42 2.31 10.46 2.05 7.71 11.86 4.09 12.86 14.46

Flourene 0.00 2.72 0.00 6.83 0.00 6.81 0.00 2.46 0.00 10.29

Phenanthrene 487.66 2.80 0.00 202.75 0.00 119.79 93.19 111.58 176.65 0.79

Anthracene 0.00 648.84 0.00 1.28 0.00 0.61 11.72 1.14 16.86 2.03

Flouranthene 1.80 30.69 12.10 0.00 8.34 0.70 15.12 1.00 8.14 0.00

Pyrene 0.00 19.96 7.99 6.11 6.55 3.45 9.16 34.51 1.01 4.80

Chrysene 0.00 0.00 0.00 0.41 0.00 3.82 0.00 0.22 0.00 27.95

1, 2 - Benzanthracene 119.03 46.17 48.44 45.04 231.63 250.92 223.06 0.00 100.46 14.92


Benzo(a)pyrene 14.79 0.00 0.00 0.00 0.00 0.00 80.47 0.00 6.46 31.54


1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00 8.67 0.00 8.06 0.00



It was observed in Chapter 4 that naphthalene was consistently the compound

emitted in the largest quantities across the full range of throttle settings. While some

of the other compounds have higher values at one particular throttle setting, or for

just one of the lubricants, naphthalene displays a consistently increasing rate of

emission with increasing throttle setting. It is also observed that the rates of emission

of naphthalene when the EAL was used were always lower.

When attempting to make a comparison between all of the other data, there is no one

trend to base a conclusion on. At a first glance it would appear that when the mineral

lubricant is used that, overall, there are more PAHs emitted. However, there are

some instances; for example, anthracene, fluoranthene and pyrene at 20% throttle,

where the rates of emission were higher when the EAL was used.

As another example of the difficulty in forming conclusions; reviewing the results

for phenanthrene, at 20% throttle the emission rate was much higher when the

mineral lubricant was used, but at 40% and 60% they were much higher when the

EAL was used. At 80% the rates were similar and at 100% again they were much

higher when the mineral oil was used. Similar observations are evident across the

range of pollutants and throttle settings, therefore, an alternative method of analysis

is required if conclusions are to be formed based on these results. It was decided to

use a statistical technique called a Principal Components Analysis (PCA), otherwise

known as a Factor Analysis, in an effort to form conclusion about the results.



A PCA is a statistical technique for studying matrices of data, and the aim of a PCA

is to summarise the interrelationships among a number of variables in a concise but

accurate manner to aid in conceptualising the entire data set. It does this by linearly

transforming an original set of variables into a substantially smaller set of

uncorrelated variables that represents most of the information in the original set of

variables. More simply, it attempts to look for the least number of components that

contribute to most of the variance in the entire data set (Dunteman, 1989).

Even though the retained principal components may be interpretable, rotating them

to a new set of coordinate axis in the same subspace, which is spanned by the

principal components, is more conceptually appealing, and allows for a simpler

interpretation of the results (Dunteman, 1989).

Figure 41 is a summary of the PCA with the graph showing the components on the x-

axis and each component having the ten variables of the mineral lubricant at each of

the five throttle settings, and the EAL at each of the five throttle settings. The first

five bars above the components represent the mineral lubricant results and the next

five the EAL results, as indicated by the legend. Each variable, through a series of

matrix operations, is eventually normalised to a value of between zero and one.



MIN20MIN40MIN60MIN80MIN100

BIO20BIO40BIO60BIO80BIO100

Variables

Rotated Component Matrix

1 2

Component

0.000

0.250

0.500

0.750

1.000

Valu

es

Figure 41: PCA Graph for the Comparison of the Lab Two-Stroke Engine Tests – Mineral vs. EAL

In this comparative analysis our data set reduced to two influencing components,

which combined accounted for 79% of the data set variance. Component 1 accounts

for 54% of the variance in the data, and as can be seen in the graph, the mineral oil

results more readily fall within this factor of influence, with the EAL results (referred

to as Bio 20 - 100) showing less of an influence. Component 2 accounts for 25% of

the variance and we can see here that the results are not so prominent, but again, the

min20 result (mineral lubricant at 20% throttle setting) is the biggest influencing data

to this factor, closely followed by some of the EAL results. From this we can

conclude, statistically, that a two-stroke engine of this design will have lower

emissions rates of PAHs when the EAL is used.

5.2 Mineral vs. EAL Field Tests PAH Results

To re-iterate, the tests conducted in the field were a scaled down version of the

laboratory tests due to time and resource limitations. The tests were conducted at the



three throttle settings of 20%, 60% and 100% rather than the five of the previous

tests. Table 26 below summarises the data for this comparison.

Table 26: Emission Rates of the PAH Pollutants when using both Lubricants - Field Tests

As with the previous data set, naphthalene was the compound emitted consistently

across all of the throttle settings, and when using both lubricants. Further, apart from

benzo(a)pyrene at 20% throttle when using the mineral oil, and pyrene at 20%

throttle when using the EAL, naphthalene was the compound emitted in the highest

quantities. It is also observed that in terms of PAH emissions, 60% throttle setting is

the most inefficient when using the mineral lubricant, opposed to 20% throttle when

using the EAL. Again however, there are no particular trends in the data upon which

to base conclusions; a PCA follows (Figure 42).

COMPOUND

Mean @ 20% Throttle


Mean @ 20% Throttle

(ug/kW.hr) EAL

Mean @ 60% Throttle


Mean @ 60% Throttle

(ug/kW.hr) EAL




(ug/kW.hr) EAL

Naphthalene 197.45 469.57 535.85 428.46 569.55 691.72

Acenaphthylene 24.14 1.58 0.00 1.69 6.83 0.00

Acenaphthene 0.00 28.77 6.32 6.30 6.50 7.04

Flourene 0.00 0.00 0.00 2.45 0.00 26.25

Phenanthrene/Anthracene 28.64 153.93 0.00 -0.75 22.52 0.00

Flouranthene 0.00 130.00 44.66 2.99 20.45 0.00

Pyrene 0.00 699.76 0.00 27.56 8.30 33.36

Chrysene 0.00 0.00 0.00 0.00 0.00 0.00

1, 2 - Benzanthracene 0.00 0.00 137.03 0.00 0.00 0.00


Benzo(a)pyrene 812.96 0.00 0.00 0.00 8.72 14.87


1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00



MIN20MIN60MIN100BIO20BIO60BIO100

Variables


1 2

Component

0.000

0.500

1.000

Valu

es

Figure 42: PCA Graph for the Comparison of the Field Test Results – Mineral vs. EAL

In this comparative analysis our data set again reduced to two influencing

components, which combined accounted for 87% of the data set variance.

Component 1 accounts for 70% of the variance in the data, and as can be seen in the

graph, the results for both lubricants for the 60% and 100% showed little difference.

For the 20% throttle setting results however, the EAL was more of an influence in

the variance of the data set. In this case, component 2 accounts for 17% of the

variance and we can see here that the min20 result is the biggest influencing data to

this factor, and all of the other results of no statistical influence. From this analysis it

is not possible to draw any conclusions as to whether or not one type of lubricant is

better to use rather than another in seawater.



5.3 Fresh Water vs. Sea Water PAH Results - Mineral Oil

To continue with the premise of this project, a comparison between the results of the

freshwater and seawater tests when using the mineral lubricant is conducted. Table

27 below summarises the data for this comparison.

Table 27: Emission Rates of the PAHs when using the Mineral Lubricant – Laboratory vs. Field Tests

Naphthalene again was emitted consistently across all of the throttle settings, but at

higher rates when the seawater tests were conducted. Overall, however, there were

more PAHs emitted during the laboratory (freshwater) tests across all of the throttle

settings. Yet the benzo(a)pyrene result for the seawater 20% throttle test had the

highest rate of emission overall.

Unlike the previous comparison between the uses of the two lubricants for the field

tests, in this case there were a number of compounds emitted at relatively high rates

when compared to naphthalene. For example; phenanthrene/anthracene at 20% and

100% throttle when in freshwater, 1, 2 benzanthracene across all of the throttle

COMPOUND

Fresh Water Mean @ 20%

Throttle (ug/kW.hr) Mineral Oil

Sea Water Mean @ 20%










Naphthalene 63.23 197.45 231.10 535.85 421.62 569.55

Acenaphthylene 2.12 24.14 0.00 0.00 0.13 6.83

Acenaphthene 34.83 0.00 2.05 6.32 12.86 6.50

Flourene 0.00 0.00 0.00 0.00 0.00 0.00

Phenanthrene/Anthracene 487.66 28.64 0.00 0.00 176.65 22.52

Flouranthene 1.80 0.00 8.34 44.66 8.14 20.45

Pyrene 0.00 0.00 6.55 0.00 1.01 8.30

Chrysene 0.00 0.00 0.00 0.00 0.00 0.00

1, 2 - Benzanthracene 119.03 0.00 231.63 137.03 100.46 0.00


Benzo(a)pyrene 14.79 812.96 0.00 0.00 6.46 8.72


1.12 - Benzoperylene 0.00 0.00 0.00 0.00 8.06 0.00



settings when in freshwater, and benzo(k)fluoranthrene when in seawater at

40%throttle.

MIN20TANMIN60TANMIN100TAMIN20SEAMIN60SEAMIN100SE

Variables


1 2

Component

-0.400

0.000

0.400

0.800

Valu

es

Figure 43: PCA Graph for the Comparison of the Laboratory and Field Test Results – Mineral Oil

The two influencing components in this analysis accounted for 77% of the variance

in the data set. Component 1 accounts for 59% of the variance in the data, and as can

be seen in Figure 43; the results in both freshwater and seawater for the 60% and

100% showed little difference but were statistically significant. For the 20% throttle

setting results however, neither the freshwater nor the seawater was a contributor the

data set variance. Component 2 accounts for 18% of the variance and we can see

here that the min20 seawater result is the biggest influencing data to this factor, and

all of the other results of no statistical influence. From this analysis it is not possible

to draw any conclusions as to whether or not the emissions to seawater or freshwater

are greater when using the mineral lubricant.



5.4 Fresh Water vs. Sea Water PAH Results – EAL

The comparison of the results now extends to the emission rates in the seawater and

freshwater when using the EAL. Table 28 below summarises the data for this

comparison.

Table 28: Emission Rates of the PAHs when using the EAL – Laboratory vs. Field Tests

As with all of the previous Tables in this chapter, naphthalene is the compound

emitted at significant levels consistently across all of the throttle settings. Further, as

with Table 27, Table 28 shows that naphthalene was emitted at significantly higher

quantities in the seawater tests. Another observation is that there are more PAHs

emitted to the freshwater than the seawater when using the EAL. Yet pyrene was

emitted at the highest rate overall at 20% throttle in seawater.

As with the previous comparison between the use of the mineral lubricant for the

field tests, in this case when the EAL was used there were a number of compounds

emitted at relatively high rates when compared to naphthalene. For example;

COMPOUND


Throttle (ug/kW.hr) EAL











Naphthalene 20.05 469.57 118.39 428.46 264.00 691.72

Acenaphthylene 11.14 1.58 2.87 1.69 1.84 0.00

Acenaphthene 21.42 28.77 7.71 6.30 14.46 7.04

Flourene 2.72 0.00 6.81 2.45 10.29 26.25

Phenanthrene/Anthracene 2.80 153.93 119.79 -0.75 0.79 0.00

Flouranthene 30.69 130.00 0.70 2.99 0.00 0.00

Pyrene 19.96 699.76 3.45 27.56 4.80 33.36

Chrysene 0.00 0.00 3.82 0.00 27.95 0.00

1, 2 - Benzanthracene 46.17 0.00 250.92 0.00 14.92 0.00


Benzo(a)pyrene 0.00 0.00 0.00 0.00 31.54 14.87


1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00



phenanthrene/anthracene and 1, 2 benzanthracene at 40% throttle when in the

freshwater, phenanthrene/anthracene and fluoranthene at 40% throttle when in

seawater, and benzo(k)fluoranthrene at 100% when in the freshwater.

BIO20TANBIO60TANBIO100TABIO20SEABIO60SEABIO100SE

Variables


1 2

Component

-0.500

0.000

0.500

1.000

Valu

es

Figure 44: PCA Graph for the Comparison of the Laboratory and Field Test Results – EAL

For this analysis the two influencing components accounted for 73% of the variance

in the data set. Component 1 accounts for 53% of the variance in the data, and as can

be seen in Figure 44; the result for the freshwater 100% throttle test (BIO100TAN)

was significant, as were all of the seawater results. The 20% and 40% throttle setting

results in freshwater were not contributors to the data set variance in component 1.

Component 2 accounts for 20% of the variance and we can see here that the

freshwater 20% test was the biggest influencing data to this factor, and all of the

other results of no statistical influence. From this analysis it can be concluded that

when the EAL is used, there will be more PAHs emitted to seawater.




The solubility of common PAHs in water at 25°C decreases in the order: naphthalene

>acenapthylene >acenapthene >fluorene> phenanathrene> fluoranthene >pyrene>

benzo(k)fluroanthene (Manoli et al., 1999). It is therefore not surprising that

naphthalene is the most abundant PAH in many of the samples tested.

Neff, (1979), reports that one of the most important characteristics of PAHs relative

to their incidence in water is solubility. PAHs are non-polar hydrophobic

compounds and therefore have quite low solubilities. Nevertheless, Neff (1979)

suggests that the limited literature available as to PAH solubility shows some definite

trends. Firstly, solubility tends to decrease as molecular weight increases. The

results obtained in this study agree with this trend, particularly at the lower throttle

settings.

In addition, of particular interest to this study is a comparison of the concentrations

of these compounds in seawater compared to that in fresh water. Neff (1979) reports

that PAHs are slightly less soluble in seawater than they are in fresh water, due to

“salting out”, however the differences are not large. Yet it was observed that the

concentrations of naphthalene, across all of the throttle settings and using both

lubricants, were higher in the seawater rather than the freshwater. This is likely

because of the suspended organic and inorganic material in the seawater during the

tests. In reality, if the tests were conducted in actual freshwater rather than tap water,

the results could have been different. However, the tests in the laboratory, in

addition to providing measurable results, were also a test of the procedure, which

was found to be appropriate for the experiments.



In keeping with observations reported elsewhere for other environmentally adapted

lubricants (Juttner et al., 1995a, Juttner et al., 1995b), there is no consistent

difference in the amount of pollutants from two-stroke engines when using either the

EAL or the equivalent mineral oil. It appears that the main benefits of EALs might

be their biodegradability and low toxicity rather than a reduction of emissions.

Another point to consider however is the type of compounds emitted when the

lubricant is used, more specifically, not simply PAHs, but the types of PAHs.

If one notes the carcinogenic potency for a range of PAH compounds; the PAHs

chrysene, 1, 2 benzanthracene, benzo(k)flouranthrene, benzo(a)pyrene, 1.2:5.6 –

dibenzanthracene and indeno[1,2,3cd]pyrene are defined as either probable human

carcinogens or possible human carcinogens (Manoli et al., 1999). When comparing

the results in Tables 25 and 26, the rates of emission of these carcinogenic

compounds are often higher when the mineral based lubricant is used.

The results have shown that the type of lubricant that is used does not affect the

amount of pollutants produced. In this study however, the lubricants are mixed as

per the engine manufacturers specifications, i.e., in a 50:1 ratio. It has been shown

(Havet et al., 2001) that EALs have superior tribological properties when compared

to classical lubricants. A further study could be conducted that varies the fuel/oil

ratio, to determine if the emission rates of these of pollutants could be improved,

while still maintaining appropriate lubricating requirements.


Chapter 6 – Volatile Organic Compounds Analysis 130

CCHHAAPPTTEERR 66

Volatile Organic Compounds Analysis for the Two-Stroke

Engine

As with Chapter 5, revisiting and summarising part of the literature; VOCs such as

benzene, toluene, ethylbenzene and xylenes are the simplest of the aromatic

hydrocarbons group. They are important and common aromatic solvents used for

adhesives, resins, pesticides, ink, and in the rubber industry. Benzene and toluene

are used as fuel additives, and xylenes are used in aviation fuel and in polymer

manufacture. Ethylbenzene is a constituent of crude oil, and these compounds

together, referred to as the BTEX group, are products of oil refining (ANZECC,

2000).

It has been noted that two-stroke outboard engines are notorious for emitting

significant amounts of unburned hydrocarbons into the environment. These liquid

fuels, which readily vaporize, are VOCs, and further, they are a significant

contributor to the problem of photochemical smog production (Baird, 1999). It is

reported that the high volatility and relatively low water solubility of these

compounds indicates that they would be rapidly lost to the atmosphere from a water

body; with half-lives for evaporation of less than 5 hours at 20°C.

Further, it is also suggested that benzene and toluene are not expected to adsorb

strongly to sediments, biodegradation is very rapid, and the BTEX group of

compounds do not bio-accumulate. It is acknowledged however, that their toxic

effects are additive (ANZECC, 2000). It is not expected that VOCs from outboard



engines would cause measurable detriment to the aquatic environment. In fact, while

the emissions rates presented in the results seem high, another study by (Loberto et

al., 2003) has shown that when the dispersion of these pollutants is taken into

account, the concentration that remains in the water is ultimately much lower than

the ANZECC water quality guidelines. The dilutions of these compounds will be

reviewed in more detail in Chapter 8.

6.1 Mineral vs. EAL Laboratory Tests VOC Results

Following is a detailed comparison between the VOC results when using the two

types of lubricants in the laboratory tests. Table 29 below summarises the data for

this comparison.

Table 29: Emission Rates of the VOC Pollutants when using both Lubricants - Laboratory Tests

Table 29 shows that in almost all instances, with the exception of ethyl benzene and

o & m xylenes at 80% throttle, that when the EAL is used the emission rates of the

VOC compounds in higher. While for the remaining compounds the emission rates

are still higher when the EAL is used at 20% and 40% throttle, but lower for the

throttle settings of 60% and 80%. The rates of emission are very similar at 100%

throttle.

COMPOUND

Mean @ 20% Throttle


Mean @ 20% Throttle

(ug/kW.hr) EAL

Mean @ 40% Throttle


Mean @ 40% Throttle

(ug/kW.hr) EAL

Mean @ 60% Throttle


Mean @ 60% Throttle

(ug/kW.hr) EAL

Mean @ 80% Throttle


Mean @ 80% Throttle

(ug/kW.hr) EAL




(ug/kW.hr) EAL

Benzene 1119.09 2271.97 3051.33 3496.30 2446.32 3232.19 2247.12 2835.61 3161.68 3954.27

Toluene 3111.13 6232.60 10195.38 11419.99 8422.16 10431.27 7799.94 9031.72 11102.02 13418.26

Ethyl benzene 333.28 746.13 1427.08 1534.02 1298.40 1321.94 1127.82 1040.38 1524.00 1811.47

o, m-xylenes 1022.90 1820.55 4125.61 4442.29 3707.70 3661.83 3275.96 2909.30 4477.84 5443.81

p-xylene 759.65 1422.66 2737.70 3233.38 2444.35 2658.80 2201.80 2251.31 3142.24 3666.86

C3 benzenes 1846.00 5079.33 10840.30 14028.41 10078.39 9651.62 8372.65 6961.37 11109.19 11691.54

C4 benzenes 1137.59 1999.79 7139.28 9221.16 7003.40 5761.37 5499.25 3889.26 6705.16 6494.22

Naphthalene 0.00 29.23 92.34 144.50 94.31 91.72 135.92 89.89 129.96 188.00




Further, if comparing the emission rates to those of the PAHs they are almost always

at least one order of magnitude higher, and on some occasions two. This is likely

due the concentrations of the compounds in the raw fuel and not due to the

concentrations in the oils themselves. Although, there is no apparent explanation as

to why the emission rates of the BTEX group of compounds would be higher when

the EAL is used. Table 15 shows there to be little difference in the concentrations of

these compounds in the raw fuel/oil mixtures.

Component : 1

Component Matrix

MIN20MIN40

MIN60MIN80

MIN100BIO20

BIO40BIO60

BIO80BIO100

Variables

0.200

0.400

0.600

0.800

1.000

Valu

es

Figure 45: PCA Graph for the Comparison of the Laboratory VOC Results

The PCA in this instance determined that there was only one influencing component

for the data set, which accounted for 97% of its variance. It can be seen in Figure 45

that all of the variables are influenced by the one component, which is likely to be

the contribution of the concentrations of the compounds in the fuel. The variables of

throttle setting or the type of lubricant did not affect the outcome of the analysis, as

can be seen by the uniform distribution of the results. It cannot be concluded from

the PCA that the type of lubricant used will affect the emission rates of the VOC

pollutants.




Roose et al., (2001), notes that the presence and distribution of volatile organic

compounds in marine and estuarine systems have so far received relatively little

attention from the scientific community. VOC compounds are thought to enter these

environments through their use as solvents and in production processes; their

formation during chlorination of drinking water and exploitation and use of fossil

fuels.

It is important to know the fate of the compounds in the aquatic environments

because a Belgian study showed that the concentration of VOCs found in the liver

and tissue of fish species from the area was 100 times the level in the surrounding

water. It was noted however, that those levels would not result in acute toxicity, and

that the current levels would probably not pose a threat to either humans or fish in

the region. Yet concerns about the long-term exposure to low levels of these

compounds are still unknown, and Roose et al., (2001), notes that a thorough

knowledge of the presence and distribution is needed for an accurate risk assessment.

As noted earlier, VOCs emitted into the marine environment are rapidly lost to the

atmosphere. This study found that the rates of emission were very low when

compared to the amounts found in the raw fuel/oil mixture; these results can be

misleading however. The results obtained were with respect to the levels solubilised

into the water, and did not take into account atmospheric losses. Based on the

information within the literature, it would be expected that the actual VOC levels

emitted would be much higher, when one considers that up to 30% of the fuel/oil

mixture can be emitted, unburnt, by two-stroke outboard motors.



One purpose of identifying VOCs within this study was because compounds such as

benzene are the “building blocks” for PAH formation. Knowing the emission rates

of the VOC and PAH compounds, and more importantly, the levels of these

compounds in the raw fuel/oil mixtures can provide us with a stepping stone to a

more detailed chemometric analysis. This level of analysis was beyond the scope of

this research.

While the concentrations in this study seem exceedingly high, Chapter 8 will show

that once diluted in the wake of the propeller their concentrations are far below the

ANZECC guideline trigger levels.


Chapter 7 – Two and Four Stroke Engine Comparisons 135

CCHHAAPPTTEERR 77

Comparison of the Two-Stroke and Four-Stroke Engine

Emissions

Past studies of outboard engines have focussed on the emissions to the atmosphere

and not the pollutants that remain in the water column. In fact the USEPA mandate

to reduce the emissions from two-stroke engines was based on the findings of such

research. Past research has shown also that a two-stroke engine can emit 87 times

more hydrocarbons into the atmosphere than a four-stroke engine (Mace, 2000). So

this comparison is conducted to determine whether or not similar trends are observed

for the pollutants that remain within the water column.

For the following comparisons, only the results for the two-stroke engine when using

the mineral lubricant are compared to those of the four-stroke engine. This is

because, unlike the two-stroke engine, the four-stroke engine has a dedicated

lubrication system that does not form part of the combustion process. Therefore,

since the four-stroke engine uses a mineral lubricant, and there has not been a

discernible difference in the emission rates when either lubricant was used for the

two-stroke engine tests, the comparison in this case has been conducted for the

engines when using the mineral lubricants. The normalised fuel consumption rates

are also compared.



7.1 PAH Results for the Two and Four Stroke Engines

Table 30 compares the emission rates from both of the engines used for the tests.

They were conducted in the laboratory using fresh tap water.

Table 30: Emission Rates of the PAHs from both the Two and Four-Stroke Engines

As with the PAH results from all of the previous tests, naphthalene was emitted

consistently across all of the throttle settings. In this case however, where there is a

steady increase in the emission rate of naphthalene when using the two-stroke

engine, there is an almost constant rate when the four-stroke engine is used. The rate

of emission also is much lower than even the lowest value at 20% throttle for the

two-stroke engine. Fluorene on the other hand was emitted at all throttle settings

when using the four-stroke engine, but not at any of the throttle settings when using

the two-stroke engine.

Another observation when looking at Table 30 is that, overall, there appears to be

fewer of the heavier PAHs emitted from the four-stroke engine. As before however,

it is difficult to draw conclusions based on a simple visual comparison of the values,

rather, a PCA is conducted in an effort to aid in this.

COMPOUND

Mean @ 20% Throttle

(ug/kW.hr) 2-Stroke Engine

Mean @ 20% Throttle


Mean @ 40% Throttle


Mean @ 40% Throttle


Mean @ 60% Throttle


Mean @ 60% Throttle


Mean @ 80% Throttle


Mean @ 80% Throttle






Naphthalene 63.23 26.69 147.54 27.27 231.10 21.08 326.75 19.07 421.62 21.05

Acenaphthylene 2.12 19.66 3.17 4.52 0.00 3.01 0.00 1.95 0.13 1.74

Acenaphthene 34.83 26.45 2.31 3.53 2.05 2.72 11.86 1.91 12.86 2.68

Flourene 0.00 63.37 0.00 17.34 0.00 12.82 0.00 8.12 0.00 8.91

Phenanthrene 487.66 23.71 0.00 17.62 0.00 9.26 93.19 9.48 176.65 11.28

Anthracene 0.00 0.00 0.00 18.34 0.00 11.53 11.72 12.20 16.86 11.20

Flouranthene 1.80 83.95 12.10 12.49 8.34 0.00 15.12 17.50 8.14 6.73

Pyrene 0.00 0.00 7.99 0.00 6.55 0.00 9.16 0.00 1.01 0.00

Chrysene 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

1, 2 - Benzanthracene 119.03 0.00 48.44 0.00 231.63 0.00 223.06 0.00 100.46 0.00


Benzo(a)pyrene 14.79 0.00 0.00 0.00 0.00 0.00 80.47 0.00 6.46 0.00


1.12 - Benzoperylene 0.00 0.00 0.00 0.00 0.00 0.00 8.67 0.00 8.06 88.62



MERC20MERC40MERC60MERC80MERC100

HOND20HOND40HOND60HOND80HOND100

Variables

1 2 3 4

Component

0.000

0.500

1.000

Valu

es


Figure 46: PCA Graph for the Comparison of the PAHs from both Engines

For this analysis there were four influencing components that accounted for 88% of

the variance in the data set. Component 1 accounts for 39% of the variance in the

data, and as can be seen in Figure 46; the results for the two-stroke engine (merc) at

40%, 60%, 80% and 100% throttle tests were the significant results. Component 2

accounted for 22% of the data set variance with the significant contributors being the

four-stroke engine 20%, 40% and 60% throttle settings. This is likely because at

these three settings there were emission rates of all of the lighter PAHs, even though

the rates were low. Component 3 accounted for 15% of the variance in the data set

and were influenced most by the four-stroke engine at 80% and 100%. The emission

rates from the two-stroke engine at these settings were worse than for the four-stroke

engine and were therefore factored into component 1. The only contributor to

component 4 was the two-stroke engine at 20% throttle, and this accounted for 12%



of the variance in the data set. It is possible to conclude from this analysis that when

the four-stroke engine is used there will fewer emissions of PAHs. However, the

confidence in this conclusion is not strong given that component 1 only accounted

for 39% of the variance, and component 2 22%.

It was decided to take a different approach to the comparison by simply summing the

emission rates of the PAHs for each of the throttle settings, and referring to them as a

rate of Total PAH Emissions; Figure 47 shows this comparison.

Comparison between the Total PAH Emissions when using the 2-Stroke and the 4-Stroke Engines

0.00

100.00

200.00

300.00

400.00

500.00

600.00

700.00

800.00

900.00

20% 40% 60% 80% 100%

Throttle Setting

Rat

e of

Tot

al P

AH

Em

issi

ons

(ug/

kWhr

)

Total PAHs - 2-Stroke EngineTotal PAHs - 4-Stroke Engine

Figure 47: A Comparison of the Total PAH Emissions from the Two and Four-Stroke Engines

It can be seen in Figure 47, that when the two-stroke engine is used that the total

PAH emissions are higher. Further, the most efficient setting for the two-stroke

engine is 40% throttle, and the most inefficient 80% throttle.



For the four-stroke engine, there is little difference between the total PAH emissions

at either 20% throttle or 100% throttle. The most efficient setting is 60% throttle.

Based on this comparison, it can be concluded that fewer PAHs will be emitted from

a four-stroke engine of this design.

7.2 VOC Results for the Two and Four Stroke Engines

Unlike the comparison of the PAH results where the differences in the rates of

emission were more subtle, the differences in the emission rates for the VOCs are

significant (Table 31).

Table 31: Emission Rates of the VOCs from both the Two and Four-Stroke Engines

For the BTEX group of compounds the emission rates are much lower for the four-

stroke engine; often at least an order of magnitude. The C3 and C4 benzenes results

showed similar differences while the naphthalene little difference. The results for

alkyl naphthalene showed that at 40%, 60% and 80% throttle, the rates of emission

were higher when the four-stroke engine was used, however, the magnitude of the

other differences more than over shadows this result. Based on these figures it is not

necessary to conduct a PCA. Rather, a more simple review of the total VOC

emissions is undertaken in the same manner as for the PAHs.

COMPOUND

Mean @ 20% Throttle


Mean @ 20% Throttle


Mean @ 40% Throttle


Mean @ 40% Throttle


Mean @ 60% Throttle


Mean @ 60% Throttle


Mean @ 80% Throttle


Mean @ 80% Throttle






Benzene 1119.09 99.94 3051.33 609.89 2446.32 308.72 2247.12 335.09 3161.68 396.57

Toluene 3111.13 173.59 10195.38 1394.91 8422.16 617.04 7799.94 673.59 11102.02 570.00

Ethyl benzene 333.28 0.00 1427.08 182.25 1298.40 75.45 1127.82 79.69 1524.00 67.23

o, m-xylenes 1022.90 0.00 4125.61 70.76 3707.70 28.96 3275.96 31.12 4477.84 26.10

p-xylene 759.65 0.00 2737.70 36.15 2444.35 15.50 2201.80 18.59 3142.24 14.66

C3 benzenes 1846.00 0.00 10840.30 945.38 10078.39 430.26 8372.65 471.32 11109.19 361.53

C4 benzenes 1137.59 0.00 7139.28 458.18 7003.40 199.83 5499.25 291.44 6705.16 195.96

Naphthalene 0.00 0.00 92.34 149.16 94.31 95.43 135.92 146.48 129.96 97.62




Comparison between the Total VOC Emissions when using the 2-Stroke and the 4-Stroke Engines

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

20% 40% 60% 80% 100%

Throttle Setting

Rat

e of

Tot

al V

OC

Em

issi

ons

(ug/

kWhr

)

Total VOCs - 2-Stroke EngineTotal VOCs - 4-Stroke Engine

Figure 48: A Comparison of the Total VOC Emissions from the Two and Four-Stroke Engines

It can be seen in Figure 48 that the emissions from the four-stroke engine are

relatively constant across all throttle settings, with 40% throttle being the most

inefficient, and 20% throttle being the most efficient. The total VOC emissions from

the two-stroke engine however are more erratic, with the most efficient setting being

20% throttle and the most inefficient being 100%, but closely followed by the 40%

throttle setting. It can be concluded from this analysis that when the four-stroke

engine is used, there will be fewer VOC emitted that remain within the water

column.

Figure 49 shows the Brake Specific Fuel Consumption (BSFC) rates for both of the

engines used in our tests. It can be seen clearly that at 20% throttle, the four-stroke

engine had a significantly lower rate of fuel consumption compared to the two-stroke

engine. There were no differences at the throttle settings of 40% and 60 %, but at

80% and 100% again the four-stroke engine used less fuel.



Comparison of Brake Specific Fuel Consumption (BSFC) between 2-Stoke and 4-Stroke Outboard Engines

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

0 20 40 60 80 100


BSF

C (L

/kW

.hr)

4-Stroke BSFC2-Stroke BSFC

Figure 49: Comparison of the Brake Specific Fuel Consumption for the Two and Four-Stroke Engines


The difference in the rates of emission of the pollutants between the two-stroke and

four-stroke engines is because of their fundamental design differences. The main

reason a two-stroke engine emits up to 30% of its fuel/oil mixture either unburnt or

partially burnt is because, for a period in the two-stroke cycle, both the inlet and

exhaust ports are open simultaneously. The fuel mixture tends to short-circuit by

passing directly from the inlet port to the exhaust port, which reduces the engine’s

efficiency considerably and leads to emission problems (Brain, 1998). Figure 50

shows a schematic of the two-stroke cycle where at 3 both the inlet and exhaust ports

are open.

halla




Further, as the engine speed increases the volume flow rate through the engine is

correspondingly higher, and as the fluid velocities increase, the amount of fuel/air

mixture short-circuiting through the system increases (Brain, 1998). The results in

Figures 47 & 48 show this occurrence.

Another problem with two-stroke engines is that they are unresponsive and do not

perform well at low RPM or idle. This is because they tend to misfire due to the

intake of the fresh air/fuel charge mixing with exhaust gases from the previous cycle.

Often the fuel will not ignite (misfire) because the resulting combined mixture is too

lean. Ignition will eventually occur when the fuel mixture becomes rich enough,

which can lead to a cycle of misfires, with combustion occurring intermittently.

Partial combustion can also occur if pockets of the air/fuel mixture are isolated from

the flame front by the exhaust gases (Brain, 1998). This point is also evidenced in

Figures 47 & 48.

Other problems that typically occur with two-stroke engines, thereby reducing their

efficiency and increasing pollution, are the exhaust may become clogged with oil

residue, and the spark plug/s can foul. These occur when the engine is held at low

RPM (low volume flow rates), which reduces the engine’s performance and may

result in the engine stalling (Brain, 1998).

The four-stroke engines are known to be more fuel efficient; therefore, their rates of

emission of the pollutants will naturally be lower. What is not evident however, on a

power to weight ratio, the emission rates might be more comparable. For example: a

4 horse-power two-stroke engine might produce the same power a six horse-power



four-stroke engine, a direct comparison, and not an adjusted investigation for power,

might be more revealing.


Chapter 8 – Pollutant Dilutions 144

CCHHAAPPTTEERR 88

Pollutant Dilutions

The results presented in this thesis so far are expressed as an emission rate rather

than a concentration remaining in the water, therefore, a direct comparison to any

water quality standards cannot be immediately made. The advantage of expressing

the results in this way though, is that they can now be used in a modelling project

where they can be related to any sized engine of the same design.

The emission rates in some instances seem extremely high. However, it is very

important to consider that these will be diluted considerably as they are mixed by the

action of the propeller in the water as shown by (Loberto et al., 2003). The

mathematical procedure that was used to determine the dilutions follows; for a

thorough description see (Loberto, 2004).

•

•

=m

CCionConcentrat )( 0

Where: C0 = the initial concentration of the pollutant (assumed to be evenly

distributed throughout the propeller disc area) (μg/kg)

=•

C μg of pollutant emitted relevant to a particular sized engine per

second

=•

m Mass flow rate of water through the propeller (kg/s)



sPwrEC

3600*=

•

Where: =E Emission rate of pollutant from experimental analysis (μg/kW.hr)

=Pwr The rated power of the engine under investigation at the

particular throttle setting

ρ**VAm =•

Where: =A Disc area of the propeller (m2)

=V Velocity of the water through the propeller (m/s)

=ρ Density of the water (kg/m3)

AnpCPwrf

V ts

ρη2

=

Where: =η Mechanical efficiency of the drive train

=A Disc area of the propeller (m2)

=n Revolutions per second

=sf Propeller slip factor

=tC Coefficient of Thrust

=p Propeller pitch

orkg

g

m

CC μ== •

•

0 ppm

The diluted concentration for some distance is then calculated.

DCCD *0= Where CD is the diluted concentration and D is the dilution factor.



m

dxkD ⎟⎠⎞

⎜⎝⎛=

Where: =k Initial concentration co-efficient = 6.74 * 10-4

=dx Down stream location divided by propeller diameter

=m Decay exponent = -0.5

The variables k and m are from the upstream dye release at 1500 rpm (Loberto,

2004), and were determined experimentally using a Laser Doppler Anemometer.

Figure 51 shows how the concentrations of the pollutants will decay with increasing

distance from the propeller according tom

dxkD ⎟⎠⎞

⎜⎝⎛= .

1.00E-05

1.00E-04

1.00E-030 10 20 30 40 50 60 70 80 90 100

Distance from the Propeller (m)

Log(

D)

Figure 51: Shows the Decay Rate for the Pollutant Concentrations with Distance from the Propeller

The following sets of Tables are the calculated diluted initial concentrations for all of

the compounds, and for each of the experimental set-ups. Presented are the dilution

results for the two-stroke and the four-stroke engines, and for the two-stroke engine



when using the different lubricants. The calculations were also conducted for the

seawater results. The diluted concentrations for all of the above at the distance of 1

metre from the propeller are presented in Appendix C.

8.1 Dilution of the Fresh Water Laboratory PAH Results

The majority of the initial concentrations in Table 32 are below the ANZECC Water

Quality Guidelines; with the exception being naphthalene at 40%, 60%, 80% and

100% throttle settings. The levels though are only slightly above the value of

2.5μg/L concentration, which is the highest level of protection and is designed to

protect 99% of species. The concentration of naphthalene can be seen to decrease to

well below the guidelines level at just 1 metre from the propeller (see Appendix C).

Table 32: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Laboratory when using the Mineral Oil

Compound

20% Throttle Setting (ug/L)





Naphthalene 3.50E-03 2.43E+00 3.64E+00 5.10E+00 6.57E+00Acenaphthylene 1.17E-04 5.21E-02 0.00E+00 0.00E+00 2.03E-03Acenaphthene 1.93E-03 3.81E-02 3.23E-02 1.85E-01 2.00E-01

Flourene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00Phenanthrene 2.70E-02 0.00E+00 0.00E+00 1.45E+00 2.75E+00

Anthracene 0.00E+00 0.00E+00 0.00E+00 1.83E-01 2.63E-01Flouranthene 9.95E-05 1.99E-01 1.31E-01 2.36E-01 1.27E-01

Pyrene 0.00E+00 1.31E-01 1.03E-01 1.43E-01 1.58E-02Chrysene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

1, 2 - Benzanthracene 6.59E-03 7.97E-01 3.65E+00 3.48E+00 1.57E+00Benzo(k)fluoranthrene 1.79E-03 2.63E-01 2.04E-01 4.82E-01 1.80E-01

Benzo(a)pyrene 8.19E-04 0.00E+00 0.00E+00 1.26E+00 1.01E-01Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00 1.09E-01 6.50E-02

1.12 - Benzoperylene 0.00E+00 0.00E+00 0.00E+00 1.35E-01 1.26E-01

Initial PAH Pollutant Concentrations at the Propeller

When the EAL was used in the freshwater tests in the laboratory, the diluted

concentrations were again, in almost all instances, well below the ANZECC

Guideline Trigger Levels (Table 33). In this case the exceptions were naphthalene at

100% throttle, which was slightly above the highest level of protection, and

benzo(a)pyrene at 100% throttle setting. The later however is above the low

reliability trigger level because there is insufficient data to derive reliable trigger



values. It can be seen in Appendix C that at 1 metre from the propeller, the

concentrations are well below the trigger levels.

Table 33: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Laboratory when using the EAL

Compound






Naphthalene 3.27E-01 2.07E+00 1.84E+00 1.03E-01 4.19E+00Acenaphthylene 1.82E-01 2.84E-02 4.45E-02 2.35E-03 2.93E-02Acenaphthene 3.49E-01 1.71E-01 1.20E-01 6.36E-02 2.30E-01

Flourene 4.44E-02 1.12E-01 1.06E-01 3.83E-02 1.63E-01Phenanthrene 1.06E+01 3.31E+00 1.86E+00 1.74E+00 3.22E-02

Anthracene 4.57E-02 2.09E-02 9.42E-03 1.77E-02 1.25E-02Flouranthene 5.00E-01 0.00E+00 1.09E-02 1.56E-02 0.00E+00

Pyrene 3.25E-01 9.98E-02 5.35E-02 5.37E-01 7.63E-02Chrysene 0.00E+00 6.63E-03 5.92E-02 3.37E-03 4.44E-01

1, 2 - Benzanthracene 7.53E-01 7.36E-01 3.89E+00 0.00E+00 2.37E-01Benzo(k)fluoranthrene 0.00E+00 3.55E-01 1.08E-01 0.00E+00 2.09E+00

Benzo(a)pyrene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 5.01E-01

Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

1.12 - Benzoperylene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00


8.2 Dilution of the Fresh Water Laboratory VOC Results

Table 34 shows that when the mineral lubricant was used for the engine tests in the

laboratory (freshwater), the concentrations of all of the compounds were below the

ANZECC Guideline Trigger Levels. The diluted concentrations for the 1 metre

distance from the source are presented in Appendix C.

Table 34: Initial Concentrations of the VOC Pollutants for the Two-Stroke Engine Tests in the Laboratory when using the Mineral Oil

Compound






Benzene 1.90E+01 5.02E+01 3.86E+01 3.51E+01 4.93E+01Toluene 5.29E+01 1.68E+02 1.33E+02 1.22E+02 1.73E+02

Ethyl benzene 5.67E+00 2.35E+01 2.05E+01 1.76E+01 2.37E+01o, m-xylenes 1.74E+01 6.78E+01 5.85E+01 5.11E+01 6.98E+01

p-xylene 1.29E+01 4.50E+01 3.85E+01 3.44E+01 4.90E+01C3 benzenes 3.14E+01 1.78E+02 1.59E+02 1.31E+02 1.73E+02C4 benzenes 1.94E+01 1.17E+02 1.10E+02 8.58E+01 1.04E+02Naphthalene 0.00E+00 1.52E+00 1.49E+00 2.12E+00 2.03E+00

Alkyl naphthalenes 0.00E+00 0.00E+00 0.00E+00 3.81E+00 4.54E+00

Initial VOC Pollutant Concentrations at the Propeller



When the EAL was used as the lubricant (Table 35), toluene had a higher initial

concentration than the trigger levels at 40% and 100% throttle. The concentration of

180μg/L though is the low reliability trigger level, and the initial concentrations

identified are only slightly above. It can be seen in Appendix C that at 1 metre from

the propeller the concentrations decrease to well below the guidelines.

Table 35: Initial Concentrations of the VOC Pollutants for the Two-Stroke Engine Tests in the Laboratory when using the EAL

Compound






Benzene 3.70E+01 5.72E+01 5.02E+01 4.41E+01 6.28E+01Toluene 1.02E+02 1.87E+02 1.62E+02 1.41E+02 2.13E+02

Ethyl benzene 1.22E+01 2.51E+01 2.05E+01 1.62E+01 2.88E+01

o, m-xylenes 2.97E+01 7.26E+01 5.68E+01 4.53E+01 8.64E+01p-xylene 2.32E+01 5.29E+01 4.13E+01 3.50E+01 5.82E+01

C3 benzenes 8.28E+01 2.29E+02 1.50E+02 1.08E+02 1.86E+02C4 benzenes 3.26E+01 1.51E+02 8.94E+01 6.05E+01 1.03E+02Naphthalene 4.77E-01 2.36E+00 1.42E+00 1.40E+00 2.98E+00

Alkyl naphthalenes 0.00E+00 3.02E+00 0.00E+00 0.00E+00 4.03E+00


8.3 Dilution of the Sea Water PAH Results

As with the PAH results from the laboratory tests, the majority of the initial

concentrations in Table 36 are below the ANZECC Water Quality Guidelines; with

the first exception being naphthalene at each of the throttle settings. The levels of

this compound though are only slightly above the highest level of protection that is

designed to protect 99% of species. The second exception is benzo(a)pyrene at 20%

throttle, however it is assessed against the low reliability trigger level. The

concentrations of both compounds can be seen to decrease well below the guidelines

level at just 1 metre from the propeller (see Appendix C).



Table 36: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Field when using the Mineral Oil

Compound




Naphthalene 3.36E+00 8.45E+00 8.88E+00Acenaphthylene 4.11E-01 0.00E+00 1.06E-01Acenaphthene 0.00E+00 9.97E-02 1.01E-01

Flourene 0.00E+00 0.00E+00 0.00E+00Phenanthrene/Anthracene 4.87E-01 0.00E+00 3.51E-01

Flouranthene 0.00E+00 7.04E-01 3.19E-01Pyrene 0.00E+00 0.00E+00 1.29E-01

Chrysene 0.00E+00 0.00E+00 0.00E+001, 2 - Benzanthracene 0.00E+00 2.16E+00 0.00E+00Benzo(k)fluoranthrene 0.00E+00 2.57E+00 0.00E+00

Benzo(a)pyrene 1.38E+01 0.00E+00 1.36E-01

Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00

1.12 - Benzoperylene 0.00E+00 0.00E+00 0.00E+00


When the EAL was used in the seawater tests (Table 37), again the initial

concentration of naphthalene exceeded the high ANZECC levels across all throttle

settings. However, both fluoranthene and anthracene also slightly exceeded the

allowable levels at 20% throttle. Yet again, the levels exceeded are the low

reliability levels, and at a distance of 1 metre from the source, the concentrations are

diluted to well below the criterion.

Table 37: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Field when using the EAL

Compound




Naphthalene 7.65E+00 6.65E+00 1.10E+01Acenaphthylene 2.57E-02 2.63E-02 0.00E+00Acenaphthene 4.69E-01 9.77E-02 1.12E-01

Flourene 0.00E+00 3.80E-02 4.17E-01Phenanthrene/Anthracene 2.51E+00 0.00E+00 0.00E+00

Flouranthene 2.12E+00 4.64E-02 0.00E+00Pyrene 1.14E+01 4.28E-01 5.30E-01

Chrysene 0.00E+00 0.00E+00 0.00E+001, 2 - Benzanthracene 0.00E+00 0.00E+00 0.00E+00Benzo(k)fluoranthrene 0.00E+00 0.00E+00 8.07E-01

Benzo(a)pyrene 0.00E+00 0.00E+00 2.36E-01Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00





8.4 Dilution of the Four-Stroke Engine Test Results

Table 38 shows that the initial concentrations of the PAH pollutants from the four-

stroke engine were all below the ANZECC Guideline Trigger Levels. The

concentrations for the 1 metre distance are presented in Appendix C.

Table 38: Initial Concentrations of the PAH Pollutants for the Four-Stroke Engine Tests

Compound






Naphthalene 2.49E-01 2.32E-01 1.79E-01 1.61E-01 1.78E-01Acenaphthylene 1.83E-01 3.85E-02 2.55E-02 1.65E-02 1.47E-02Acenaphthene 2.47E-01 3.00E-02 2.31E-02 1.61E-02 2.26E-02

Flourene 5.91E-01 1.48E-01 1.09E-01 6.87E-02 7.53E-02Phenanthrene 2.21E-01 1.50E-01 7.84E-02 8.02E-02 9.53E-02

Anthracene 0.00E+00 1.56E-01 9.76E-02 1.03E-01 9.47E-02Flouranthene 7.83E-01 1.06E-01 0.00E+00 1.48E-01 5.69E-02

Pyrene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00Chrysene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

1, 2 - Benzanthracene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00Benzo(k)fluoranthrene 0.00E+00 0.00E+00 0.00E+00 4.79E-01 6.57E-01

Benzo(a)pyrene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.90E-01

1.12 - Benzoperylene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 7.49E-01


As with the PAHs, when the four-stroke engine was used for the tests the initial

concentrations of the VOC pollutants were well below the trigger levels (Table 39).

As before, the 1 metre distance concentrations are presented in Appendix C.

Table 39: Initial Concentrations of the VOC Pollutants for the Four-Stroke Engine Tests

Compound






Benzene 8.29E-01 4.61E+00 2.32E+00 2.52E+00 2.98E+00Toluene 1.44E+00 1.06E+01 4.65E+00 5.07E+00 4.28E+00

Ethyl benzene 0.00E+00 1.38E+00 5.68E-01 5.99E-01 5.05E-01o, m-xylenes 0.00E+00 5.35E-01 2.18E-01 2.34E-01 1.96E-01

p-xylene 0.00E+00 2.73E-01 1.17E-01 1.40E-01 1.10E-01C3 benzenes 0.00E+00 7.15E+00 3.24E+00 3.54E+00 2.72E+00C4 benzenes 0.00E+00 3.47E+00 1.50E+00 2.19E+00 1.47E+00Naphthalene 0.00E+00 1.13E+00 7.19E-01 1.10E+00 7.33E-01

Alkyl naphthalenes 0.00E+00 3.86E+00 1.41E+00 2.12E+00 8.11E-01




8.5 Two and Four-Stroke Engine Dilutions Comparisons

For these comparisons the PAH and VOC totals emissions are used; and rather than

present the results in tabular form, they are presented graphically. Figure 52 shows

how the concentrations of the total PAH emissions decrease with distance from the

propeller. Both the two and four-stroke engine emissions results are shown for 100%

throttle setting with the results normalised for power. The concentrations used to

calculate these dilutions are from Figure 47. The lower emission rates of the PAH

compounds from the four-stroke engine can be clearly seen. It is also shown that the

majority of the dispersion occurs within the first 20 metres from the propeller.

0.000

0.050

0.100

0.150

0.200

0.250

0 10 20 30 40 50 60 70 80 90 100


Tota

l Con

cent

ratio

n PA

Hs

(ug/

kg)

Figure 52: The Concentrations of the Total PAH Pollutants at 100% Throttle vs. Distance from the Source

Figure 53 shows how the concentrations of the total VOC emissions decrease with

distance from the propeller corresponding to the PAH results in Figure 52. Both the

two and four-stroke engine emissions results are shown for 100% throttle setting,

again normalised for power. The concentrations used to calculate these dilutions are

from Figure 48. The lower emission rates of the VOC compounds from the four-

Two-Stroke Engine

Four-Stroke Engine



stroke engine can be clearly seen, so much so, a logarithmic scale had to be used for

the y-axis.

0.010

0.100

1.000

10.000

100.000

0 10 20 30 40 50 60 70 80 90 100


Tota

l Con

cent

ratio

n PA

Hs

(ug/

kg)

Figure 53: The Concentrations of the Total VOC Pollutants at 100% Throttle vs. Distance from the Source

An opportunity arose during April and July of 2003, when a series of field tests were

being conducted in cooperation with the Environmental Protection Authority and the

University of Queensland, to conduct some preliminary field tests with outboard

engines. During the course of the field test several different outboard motor/boat

combinations were driven past the probe of an Acoustic Doppler Velicometer (ADV)

at different load/velocity combinations which were carefully monitored (see Figure

54). At this stage of that investigation, the ability to assess the dilution of pollutants

from the various set-ups was not possible. However, the experiments served to

develop and establish procedures for further testing that could be used for these

purposes at a later date. The results, while still being processed completely, have

provided some interesting information about the possible effects of this type of

boat/engine combination.

Two-Stroke Engine

Four-Stroke Engine

VOC



Figure 54: Outboard Engine Passing Velocity Measuring Probe

Figure 55 shows the effect of a non-planing outboard motor on the velocity field at

the point of measurement. Initially the bow wave creates a disturbance, which is

followed about 20 seconds later by the propeller induced turbulence. From

observation of the velocity data it was observed that it took up to 10 minutes for the

effect of the outboard motor to dissipate. The full environmental disturbance caused

by the wake and the characteristics of the outboard motor that can enhance/reduce

this are currently under investigation (Loberto et al., 2003).

-25

-20

-15

-10

-5

0

5

10

-50 0 50 100Time (s)

Velo

city

(cm

/s)

Vx_1Vy_1Vz_1VyVzVx

Boat PassesInitial disturbance in vertical velocity

Propeller turbulence effect

Figure 55: Velocity Disturbance Caused by an Outboard Engine in Open Water




The first impression these results give is that the contribution to aquatic pollution by

a single outboard engine is negligible. However, in Queensland alone there are

155,000 registered recreational vessels, most of which have outboard engines. This

coupled with an unknown number of unregistered recreational boats actually means

that the contribution of these pollutants to marine environments is substantial. The

dilutions above represent the concentrations behind the path of a single boat, but if

another boat crosses that path, then the concentration at that point of intersection will

be additive.

It was noted earlier that if the amounts of PAH pollutants were distributed evenly

throughout the world’s oceans and lakes, their concentrations would be negligible

(Baird, 1999); this is not the case. It is the coastal regions that are most commonly

frequented by Australian boat users, and being a tidal zone, one would expect the

pollutants to be further dispersed. Yet when these pollutants are dispersed, they

cannot remain suspended within the water column indefinitely; at some point in time

they must settle and subsequently bind to sediments. Further, a large number of

recreational boat users limit the use of their boats to areas such as estuaries, creeks

and rivers. These systems may not be completely flushed by tidal flows, and they are

known to be the breeding grounds for a multitude of marine and aquatic species,

some of which spend years in these areas until they are of a sufficient maturity to

leave. The PAH pollutants identified in this study have been shown to be persistent

in marine and aquatic environments, particularly sediments, in some cases for years.



Another concern is areas such as marinas, which have a large concentration of boats,

sometimes hundreds; that deposit a large quantity of these pollutants in a relatively

small area. The mouth of the marina can then become a point source of the

pollutants, which can be dispersed to sensitive nearby regions.

Having our results expressed as units of mass per engine power will facilitate an

estimation of how much of a particular pollutant will be emitted over some period of

time, if other information is at hand such as the number and power output of the

engines. It would then be possible to extend the investigation to include a detailed

environmental impact assessment, although this is beyond the scope of this research.


Chapter 9 – Toxicity of the Pollutants 157

CCHHAAPPTTEERR 99

Toxicity of the Pollutants

The contamination of sediments with PAHs can pose direct threats to aquatic

organisms, which tend to bioaccumulate them, and indirect threats to wildlife and

humans through the ingestion of contaminated fish and shellfish (Eljarrat et al.,

2001). To assess the relative toxicity of these compounds, the World Health

Organisation (WHO) proposed that Toxicity Equivalency Factors (TEFs) be used to

calculate the relative toxicity of the individual PAHs, and then inturn, the Total

Toxicity Equivalent PAHs (TEQPAH).

The compound 2, 3, 7, 8 – tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is a potent

inducer of liver microsomal aryl hydrocarbon hydroxylase (AHH) and is thus

referred to as AHH-active (Eljarrat et al., 2001). More simply, (Manahan, 1991),

defines the compound as super toxic, with an LD50 (the Lethal Dose required to kill

50% of an experimental population) to male guinea pigs of only 0.6 μg/kg of body

mass. TEFs are assessed for each individual compound relative to 2,3,7,8-TCDD,

where it has a TEF of 1.

Eljarrat et al., (2001), notes however, that the TEF values for PAHs are limited and

vary depending on the source and the method used to determine them. In their study,

Eljarrat et al., (2001), found that the TEFs proposed for PAHs by three other authors

differed, which were used firstly, in an attempt to calculate TEQPAH for their

sediment samples, but secondly, to highlight the differences that arise in the TEQPAH



results because there in no consensus in the TEFs for PAHs. The TEQPAH

calculations for this thesis also use the three different TEFs, which are shown below

in Table 40. Note in particular the differences between the TEFs for chrysene,

benzo(k)fluoranthrene, indeno(1,2,3 - C.D)pyrene and 1,2:5,6 – dibenzanthracene.

Table 40: The Different TEFs used by (Eljarrat et al., 2001), and used in this Study

Compound Author 1 TEFs Author 2 TEFs Author 3 TEFsAnthracene 0.0001Chrysene 0.0002 0.01

1, 2 - Benzanthracene 0.000025 0.00001 0.000027Benzo(k)fluoranthrene 0.00478 0.05 0.00029

Benzo(a)pyrene 0.000354 0.00001 0.0003Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00203 0.05 0.000078

To calculate the TEQPAH, the concentration of the compounds, (for which there is a

TEF), is multiplied by the corresponding TEF value, and those values are then

simply summed together.

Specifically for this investigation:

)*( nCPAH CTEFTEQ ∑=

Where: TEFC = is the TEF for that particular compound

Cn = is the concentration of the compound at the particular

distance from the propeller

The TEQPAH are calculated for the diluted initial concentrations (i.e. at x = 0 in the

propeller jet) from Chapter 8 (Tables 32 to 39, but excluding the VOC results) using

the TEFs from Table 40. The results are expressed as a new concentration at that

point.



Table 41: The Calculated TEQPAH using the Different TEFs and for the Two and Four-Stroke Engines and the Fresh and Seawater Results

20% Throttle 40% Throttle 60% Throttle 80% Throttle 100% Throttle

2-Stroke Fresh Water Mineral - 0mAuthor 1 TEFs 9.02E-06 1.28E-03 1.07E-03 3.06E-03 1.07E-03Author 2 TEFs 8.97E-05 1.32E-02 1.03E-02 2.96E-02 1.23E-02Author 3 TEFs 9.43E-07 9.79E-05 1.58E-04 6.19E-04 1.30E-04

2-Stroke Fresh Water EAL - 0mAuthor 1 TEFs 1.88E-05 1.72E-03 6.25E-04 6.75E-07 1.02E-02Author 2 TEFs 1.21E-05 1.78E-02 6.03E-03 3.55E-05 1.09E-01Author 3 TEFs 2.03E-05 1.23E-04 1.36E-04 0.00E+00 7.61E-04

2-Stroke Sea Water Mineral - 0mAuthor 1 TEFs 4.90E-03 1.23E-02 4.81E-05Author 2 TEFs 1.38E-04 1.28E-01 1.36E-06Author 3 TEFs 4.15E-03 8.03E-04 4.08E-05

2-Stroke Sea Water EAL - 0mAuthor 1 TEFs 0.00E+00 0.00E+00 3.94E-03Author 2 TEFs 0.00E+00 0.00E+00 4.04E-02Author 3 TEFs 0.00E+00 0.00E+00 3.05E-04

4-Stroke Fresh Water - 0mAuthor 1 TEFs 0.00E+00 0.00E+00 0.00E+00 2.29E-03 3.94E-03Author 2 TEFs 0.00E+00 1.56E-05 9.76E-06 2.39E-02 5.24E-02Author 3 TEFs 0.00E+00 0.00E+00 0.00E+00 1.39E-04 2.21E-04

TEQ PAHs for the Initial Concentrations at the Propeller (ug/L )

It can be seen in Table 41 that the initial concentrations based on toxicity are now

further diluted when compared to the initial concentrations in Chapter 8. Also note

that the four-stroke engine results are for the actual engine used in the tests for this

thesis. It has a rated power more than three times the two-stroke engine, yet the

toxicities in the propeller wake in most instances were still lower than the two-stroke

engine. Dispersion of all the PAHs occurs at the same rate and so the TEQs at

distances further downstream will differ only by the dilution factor. It can also be

observed in Table 40 that the different sources of TEFs result in considerable

variability between the TEQPAH results.

Figure 56 shows a comparison of the TEQPAH results for the two and four-stroke

engine laboratory tests and at the range of throttle settings. It can be seen that when

Author 2 TEFs are used, that the overall TEQPAH are higher. More importantly, for

the throttle settings of 20% - 80% the TEQPAH are higher when the two-stroke engine

is used, however, at 100% throttle it is higher when the four-stroke engine is used.



0.00E+00

5.00E-03

1.00E-02

1.50E-02

2.00E-02

2.50E-02

3.00E-02

3.50E-02

4.00E-02

4.50E-02

5.00E-02

5.50E-02

20 40 60 80 100


TEQ

Author 1 (2-Stroke)Author 2 (2-Stroke)Author 3 (2-Stroke)Author 1 (4-Stroke)Author 2 (4-Stroke)Author 3 (4-Stroke)

Figure 56: A Comparison of the TEQPAH between the Two and Four-Stroke Engines

Although the TEQPAH for the two-stroke engine are higher for the throttle settings of

20% to 80%, they are not higher by a factor similar to the differences in total PAHs

shown in Figure 47. This is because the TEF for benzo(k)fluoranthrene adopted by

Author 2 (see Table 40) is significantly higher than for other PAHs, and that the

concentration of this pollutant was high relative to that of the two-stroke engine at

100% throttle. This highlights the fact that simply summing the concentrations to

make an assessment of the total PAHs (as in Figure 47) is not an appropriate

approach.


The differences in the results above highlight the need for a set of uniform TEFs that

can be used worldwide. In the least, if the method of obtaining them were uniform, it

would be unlikely that significant differences would occur.



It was noted above that three different Authors presented three different sets of TEFs

for the analysis of TEQPAH. Eljarrat et al., (2001), notes that Author1 determined the

induction potency of PAHs with respect to 2378-TCDD in rat hepatoma H4IIE cells.

Author 2 examined the ability of PAHs to induce AhR-mediated luciferase activity in

mouse hepatoma cells; while Author 3 determined TEFs by comparing the induction

of EROD activity by PAH standards with those of a 2378-TCDD standard.

Inconsistencies in baseline parameters such as these TEFs show that careful

consideration needs to be adopted for an environmental assessment. One could

simply adopt the most stringent TEFs for the assessment, but this might be over

estimating the actual impacts. This inturn could result in the imposition of

unreasonable restrictions on some activity, or impose un-necessary costs to a project.

Alternatively, if one adopted the less stringent of the TEFs, the opposite could occur

where the impacts are under estimated. It is more likely that both the upper and

lower values would be used to form a range within which to work, where a

calculated value that lies somewhere in between is an acceptable level.


Chapter 10 – Conclusions and Future Research 162

CCHHAAPPTTEERR 1100

Conclusions and Future Research

10.1 Conclusions

The aims and objectives of the research project were met, in that:

• The underwater emissions from outboard engines were sampled, identified and

quantified. Variables included, two and four-stroke engines, EAL and mineral

lubricants, fresh and sea water, and throttle settings.

• Statistical analyses using Principal Components Analyses were used to compare:

The emissions from a two-stroke engine when using a mineral oil and an

equivalent EAL.

The emissions to both fresh and sea water when using both lubricants and

the two-stroke engine.

The emissions from both two and four stroke engines.

• The concentrations of the pollutants at various distances in the wake of the boat

propeller were estimated using a simple dispersion model.

• A toxicity equivalence analysis was conducted to compare the relative toxicity of

outboard engines under varied operating conditions.

Based on the above, the following specific conclusions have been determined:

• It can be concluded, statistically, that the PAH pollutants that remain in the water

column, when using a two-stroke engine of this design, will be lower when the

EAL is used, and using tap water.



• PAH emissions for the seawater tests when using a two-stroke engine of this

design are not statistically different.

• When comparing the emissions of PAHs to both the sea and freshwater, whilst

using just the mineral oil, no statistical difference was found for pollutant

retention in the water column.

• It can be concluded, statistically, that when just the EAL results are compared,

there will be more PAHs remaining in the seawater than the freshwater from a

two-stroke engine of this design.

• It cannot be concluded from the PCA that the type of lubricant used will alter the

VOC pollutants remaining in the water from a two-stroke engine of this design.

• It is concluded that fewer PAHs will remain in the water column when a four-

stroke engine of this design is used, when compared to the carburetted two-stroke

engine.

• It can be concluded from this analysis that when the four-stroke engine is used,

there will be fewer VOC compounds emitted that remain within the water

column, when compared to the carburetted two-stroke engine.

• For the two-stroke engine, in almost all instances, the initial concentrations of the

pollutants at the propeller were well below the ANZECC Guideline Trigger

Levels. From 1 metre aft of the propeller, all concentrations were well below.

• The calculated TEQPAH were mostly higher when the two-stroke engine was

used, the exception being at 100% throttle setting for the four-stroke engine.

The factors affecting pollutant concentration variations with throttle setting are

considerable, and include: fuel/lubricant composition, water salinity, water

temperature, and presence of organic matter. Other parameters could include,



air/fuel ratio, compression ratio, and engine condition/tuning. Future development of

this project is currently investigating the affect of air/fuel ratio and compression

ratio, but it is not yet complete. While it is possible to list the above factors, further

comment is not possible at present.

Ambiguity still remains as to whether or not an EAL has a positive affect on the

emissions from a two-stroke engine. The underlying fact however, is that being

vegetable oil based, the development of these products is in keeping with the concept

of ecologically sustainable development. If the emission rates from these products

are, at worst, the same as the traditional lubricating products, then the benefits of

using them must be seen from a wider perspective. It is therefore concluded that the

emissions from an outboard engine when using either an EAL or a mineral based

lubricant are similar. However, the use of EALs has further reaching advantages in

that spilt raw lubricants will degrade in the environment up to 10 times faster than a

mineral lubricant. Also EALs are less toxic to aquatic and marine organisms. The

results in this thesis for a single outboard engine now form the basis for a more

detailed environmental assessment of their impacts.

10.2 Future Research

This research started in the laboratory and made the assumption that tap water was

representative of freshwater. It is recommended that the study be moved to the field

near a body of freshwater to investigate the possibility of a higher concentration of

the pollutants remaining within the freshwater column. It is expected, based on the

literature, that this would be the case since tap water is relatively free of suspended

particulates, unlike freshwater that would have an abundant supply of organic

material in suspension. This could also be extended to an estuarine system, where it



is expected that the levels of organic, and inorganic, suspended material would be

even greater; thereby resulting in even higher concentrations.

When the above experiments are being conducted, for both two-and four-stroke

engines, other physical parameters from the water itself should be recorded, such as,

BOD, COD, pH, temperature and turbidity. The pollutant data might then be related

to these, and statistical techniques such as a PCA could reveal any possible links.

Another consideration could be the modelling of a number of boats with crossing

paths and within a finite area. This could give some estimate of the amount of each

of the pollutants within that area, and then the toxicity equivalence analysis could be

reviewed again. This might be best suited to a marina. The investigation could then

be extended to include a detailed environmental impact assessment of the site.

Given that the tribological properties of the EAL products have been shown to be

superior to equivalent mineral based oils, a further study could be conducted that

varies the fuel/oil ratio, to determine if the emission rates of these of pollutants could

be improved, while still maintaining appropriate lubricating requirements. This

research however, revealed that there may be a reduced level of lubricity at all but

the full throttle setting of the fuel/oil mixture, when the EAL was used. Other tests

should be conducted on the fuel oil mixture to determine properties such as viscosity

and octane level, to determine whether or not the EAL is the cause of the differences

in the results.



It would be advantageous to set up an engine with temperature and pressure probes

inserted into the cylinder head to attempt to correlate these variables with certain

PAHs that are produced. This would be interesting research to the wider scientific

community.


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Irwin, R. J. (Ed.) (1997b), Environmental Contaminants Encyclopedia - Chrysene

Entry, National Park Service, Water Resources Divisions, Water Operations Branch, Fort Collins, Colorado. http://www.nature.nps.gov/hazardssafety/toxic/index.html


References 169

Irwin, R. J. (Ed.) (1997c), Environmental Contaminants Encyclopedia - Fluorene Entry, National Park Service, Water Resources Divisions, Water Operations Branch, Fort Collins, Colorado. http://www.nature.nps.gov/hazardssafety/toxic/index.html

Juttner, F., Backhaus, D., Matthias, U., Essers, U., Greiner, R. and Mahr, B. (1995a)

Emissions of Two and Four-Stroke Outboard Engines - I: Quantification of Gases and VOC, Water Resourses, 29, 1976-1982

Juttner, F., Backhaus, D., Matthias, U., Essers, U., Greiner, R. and Mahr, B. (1995b)

Emissions of Two and Four-Stroke Outboard Engines - II: Impacts on Water Quality, Water Resourses, 29, 1983-1987

Kado, N. Y., Okamoto, R. A., Karim, J. and Kuzmicky, P. A. (2000) Airborne

Particle Emissions from 2 and 4-Stroke Outboard Marine Engines: Polycyclic Aromatic Hydrocarbon and Bioassay Analysis, Environmental Science & Technology, 34, 2714-2720

Kelly, C. A., Brown, R. J., Rae, D., Scott, W. and Hargreaves, D. (2001a), A

Comparison of Mineral and Biodegradable Marine Two-Stroke Lubricants, 2nd World Tribology Congress, Vienna, Austria

Kelly, C. A., Rasul, M. and Brown, R. J. (2001b), Characterisation of Marine Two-

Stroke Outboard Engine Emissions to Water, 6th World Congress of Chemical Engineering, Melbourne, Australia

Kokot, S., Griggs, M., Panayiotou, H., and Phuong, T.D., (1998), Data Interpretation

by some Common Chemometrics Methods, Electroanalysis, 10, 16, 1081-1088

Lewis, R. (2001) Tribology

,http://www.shef.ac.uk/~mpe/tribology/teaching/wit/wit_intr.html, 22/3/2001 Loberto, A. R. (2004) An Experimental Investigation into the Wakes of Boat

Propellers, Queensland University of Technology, Masters Thesis (in preparation)

Loberto, A. R., Brown, R. J. and Kelly, C. A. (2003), Assessing Environmental

Impacts of Two-Stroke Outboard Motor Lubricants Using Tank Testing and Simple Dispersion Model, National Environment Conference 2003, Brisbane, Australia

Mace, B. E. (2000) Emissions Testing of Two Recreational Marine Engines with

Water Contact in the Exhaust Stream, West Virginia University, Master of Science in Mechanical Engineering

Manahan, S. E. (1991) Toxicological Chemistry - A Guide to Toxic Substances in

Chemistry, Lewis Publishers, Inc., Michigan, USA.


References 170

Manoli, E. and Samara, C. (1999) Polycyclic Aromatic Hydrocarbons in Natural Waters: Sources, Occurrence and Analysis, Trends in Analytical Chemistry, 18

Marshall, B. (2001) How do Two-Stroke Engines Work?,

http://www.howstuffswork.com/two-stroke.htm, 21/08/2001 Martin, L. C. (1999) Caught in the Wake: The Environmental and Human Health

Impacts of Personal Watercraft, Izaak Walton League of America McFall, D. (2002) Outboard Engine Revolution?, Lubes 'n' Greases, 8, 6 - 12 Morgan, E. J. and Lincoln, R. H. (1990) Duty Cycle for Recreational Marine

Engines, SAE International Neff, J. M. (1979) Polycyclic Aromatic Hydrocarbons in the Aquatic Environment:

Sources, Fates and Biological Effects, Applied Science Publishers Ltd, London.

Nelson, J. (2000a) Harvesting Lubricants, The Carbohydrate Economy,

3.http://www.carbohydrateeconomy.org/library/admin/uploadfiles Nelson, P. (2000b) Australia's National Plan to Combat Pollution of the Sea by Oil

and Other Noxious and Hazardous Substances - Overview and Current Issues, Spill Science and Technology Bulletin, 6, 3-11

Opresko, D. M. (1991) Toxicity Summary for Ethylbenzene, Oak Ridge National

Laboratory http://risk.lsd.ornl.gov/tox/rap_toxp.shtml, 3/12/2001 Priest, M. W., Williams, D. J. and Bridgman, H. A. (2000) Emissions from In-use

Lawn-mowers in Australia, Atmospheric Environment, 34, 657-664 Queensland Department of Transport (2001) Recreational Vessels Registered in

Queensland: by Local Authority and Length, Queensland Department of Transport, Register

Queensland Transport: Marine Pollution Section (1989) Marine Oil Pollution: Its

Potential Impact and Control, Queensland Transport, Rea, D. A. (2001) The Dispersion of Pollutants from Marine Two-Stroke Outboard

Engines - Engine Emissions, Queensland University of Technology, Undergraduate Final Year Project

Roose, P., Dewulf, J., Udo, A., Brinkman, T. and Van Langehove, H. (2001)

Measurement of Volatile Organic Compounds in Sediments of the Scheldt Estuary and the Southern North Sea, Wat. Res., 35, 1478 - 1488

Rye, H., Johansen, O., Reed, M., Ekrol, N. and Deqi, X. (2000) Exposure of Fish

Larvae to Hydrocarbon Concentration Fields Generated by Subsurface Blowouts, Spill Science and Technology Bulletin, 6, 113-123


References 171

Tjarnlund, U., Ericson, G., Lindesjoo, E., Petterson, I., Akerman, G. and Balk, L. (1996) Further Studies of the Effects of Exhaust from Two-Stroke Outboard Motors on Fish, Marine Environmental Research, 42, 267-271

Tjarnlund, U., Ericson, G., Lindesjoo, E., Petterson, I. and Balk, L. (1995)

Investigation of the Biological Effects of 2-Cycle Outboard Engines' Exhaust on Fish, Marine Environmental Research, 39, 313-316

USEPA (1974) Assessing Effects on Water Quality by Boating Activity, U.S.

Environmental Protection Agency: National Environmental Research Center, USEPA (1988) Guidance for State Implementation of Water Quality Standards for

CWA Section 303(C)(2)(B), USEPA, Office of Water Regulations and Standards

van der Waal, G. and Kenbeek, D. (1993) Testing, Application, and Future

Development of Environmentally Friendly Esther Base Fluids, J. Synthetic Lubrication, 10, 67-83

van Leersum, J., (1998), A Numerical Model of a High Performance Two-Stroke

Engine, Applied Numerical Mathematics, 27, 83 - 108 Warrington, P. (1999) Impacts of Recreational Boating on the Aquatic Environment,

British Columbia Lake Stewardship Society http://www.nalms.org/bclss/impactsrecreationboat.htm, 22/01/2001

Weiner, E. R. (2000) Applications of Environmental Chemistry: A Practical Guide

for Environmental Professionals, Lewis Publishers, Washington, D.C. Woo, A. (2002) Field Testing of an Outboard Motor and Engine Modelling,

Queensland University of Technology, Undergraduate Final Year Project Yen, T. F. (1999) Environmental Chemistry: Essentials of Chemistry for Engineering

Practice, Prentice-Hall Inc., New Jersey. Zhou, W. and Ye, S.-h. (1998) Effects of Two New Lubricants on the Mutagenicity of

Scooter Exhaust Particulate Matter, Mutation Research, 4, 131-137


Appendix A – Preliminary Results 172

AAPPPPEENNDDIIXX AA –– RReessuullttss ooff tthhee PPrreelliimmiinnaarryy PPoolllluuttaanntt

IInnvveessttiiggaattiioonn

halla




halla




halla



Appendix B – Sample Calculations 175

AAPPPPEENNDDIIXX BB –– SSaammppllee CCaallccuullaattiioonnss

The data obtained from the analyses were provided in terms of parts per million

(ppm); these had to be corrected based on the sample volume and the extracted

volume from the above procedures. Example calculations follow for this and the

previously mentioned corrections; the recovery efficiency calculation is also shown.

The calculations shown are from the data recovered for the naphthalene

concentration in the mineral oil 100% throttle test – run 1, and are presented finally

in terms of μg/L.

Data

Sample Volume: 100mL - Vsample

Extracted Volume: 1.5mL – Vextract

Known concentration of naphthalene in the standard mix: 100μg/mL – Kconc

Detected concentration of naphthalene in the standard mix: 98.36μg/mL – Dconc

Detected concentration of naphthalene in min oil blank sample: 0.19μg/mL – Bconc

Detected concentration of naphthalene in the mineral oil 100% throttle test:

10.70μg/mL – Nconc

Initial Corrections

The initial detected concentrations in the blank sample and the 100% throttle setting

sample were corrected for the difference in the detected concentration of the standard

mix as follows.



Blank Sample

mLgmLgmLgmLgB

DK

concconc

conc /193.0/190.0*/360.98/000.100* μμ

μμ

=⎟⎟⎠

⎞⎜⎜⎝

⎛⇒⎟⎟

⎠

⎞⎜⎜⎝

⎛

100% Throttle Setting Sample

mLgmLgmLgmLgN

DK

concconc

conc /878.10/700.10*/360.98/000.100* μμ

μμ

=⎟⎟⎠

⎞⎜⎜⎝

⎛⇒⎟⎟

⎠

⎞⎜⎜⎝

⎛

Next, the concentration found in the blank sample was deducted from the

concentration found in the 100% throttle-setting sample.

mLgmLgmLg /685.10/193.0/878.10 μμμ =−

Further Corrections

The concentration above is expressed in terms of μg/mL; however, this represents the

concentration in the extracted sample and not the actual concentration that occurs in

the test tank. Given that we know the sample volume and the extracted volume, we

can determine the actual concentration in the test tank water as follows.

If the required concentration is x μg/mL, then there must be x * 1.5μg in 1.5mL,

where x is the detected concentration. Since this came from a 100mL sample of

water, the actual concentration is simply determined as:

( ) ( ) mLgmL

gV

VCCsample

extractk /160.0

1005.1*685.10*100

tan μμ=⇒=

&& .

There now needs to be another correction based on the recovery efficiency of the

extraction procedure. After processing and correcting the spiked samples using the

above procedure, the mean concentration of naphthalene found in the spiked samples



was 2.20μg/mL. The known concentration of the spike was 3.00μg/mL. Therefore,

the recovery efficiency for naphthalene was determined to be:

733.0/00.3/20.2

=mLgmLg

μμ or 73.3%.

The next correction was made to account for the recovery efficiency and the

subsequent value expressed in terms of μg/L.

LgLmL

mLg

mLgmLgCCeryre

kactual

/2181

1000*1218.0

/218.0733.01*/160.01*

covtan

μμ

μμη

=

=⎟⎠⎞

⎜⎝⎛⇒⎟

⎟⎠

⎞⎜⎜⎝

⎛= &

The above value represents the concentration in the test tank; a figure not of much

use because it is an amount confined to a finite volume of water. Realistically, this

amount of pollutant would be dispersed into some undefined volume of water, and

hence more calculations are needed.

It was decided to express the results as an emission rate that could eventually be

related to all outboard engines of this design. The first step to doing this was to

express the results as an amount of pollutant emitted per litre of fuel/oil mixture

consumed; the calculation follows.

The engine run took 1200 seconds, and the rate of fuel consumption during that time

was 0.395mL/s. The conversion from concentration to amount of naphthalene

emitted per litre of fuel consumed is:

( ) actualFC CTFC

LLmLC *

*1*

11000

=&



( ) 9.459/218*1200*/395.0

1*1

1000=Lg

ssmLL

LmL μ μg/L of fuel consumed

The final conversion was to express the result as an emission rate; the calculations

follow.

gg

PwrFCCE FCn μ1000000

1*1**&& =

hrkWg

kWhrLLg

.7.362

809.11*/422.1*/9.459 μμ =⎟

⎠⎞

⎜⎝⎛


Appendix C – Pollutant Dilutions 179

AAPPPPEENNDDIIXX CC –– PPoolllluuttaanntt DDiilluuttiioonnss

Diluted concentrations of the PAH pollutants 1 metre from the propeller when using

the mineral lubricant for the two-stroke engine laboratory tests.

Compound






Naphthalene 1.06E-06 7.31E-04 1.10E-03 1.54E-03 1.98E-03Acenaphthylene 3.53E-08 1.57E-05 0.00E+00 0.00E+00 6.13E-07Acenaphthene 5.81E-07 1.15E-05 9.75E-06 5.58E-05 6.04E-05

Flourene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00Phenanthrene 8.14E-06 0.00E+00 0.00E+00 4.38E-04 8.30E-04

Anthracene 0.00E+00 0.00E+00 0.00E+00 5.51E-05 7.92E-05Flouranthene 3.00E-08 6.00E-05 3.96E-05 7.11E-05 3.83E-05

Pyrene 0.00E+00 3.96E-05 3.12E-05 4.31E-05 4.76E-06Chrysene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

1, 2 - Benzanthracene 1.99E-06 2.40E-04 1.10E-03 1.05E-03 4.72E-04Benzo(k)fluoranthrene 5.40E-07 7.94E-05 6.16E-05 1.45E-04 5.43E-05

Benzo(a)pyrene 2.47E-07 0.00E+00 0.00E+00 3.79E-04 3.03E-05Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00 3.28E-05 1.96E-05

1.12 - Benzoperylene 0.00E+00 0.00E+00 0.00E+00 4.08E-05 3.79E-05

Diluted Concentrations at a Distance of 1m from the Propeller


the EAL for the two-stroke engine laboratory tests.

Compound








Anthracene 1.38E-05 6.30E-06 2.84E-06 5.34E-06 3.77E-06Flouranthene 1.51E-04 0.00E+00 3.27E-06 4.69E-06 0.00E+00

Pyrene 9.81E-05 3.01E-05 1.61E-05 1.62E-04 2.30E-05Chrysene 0.00E+00 2.00E-06 1.79E-05 1.02E-06 1.34E-04

1, 2 - Benzanthracene 2.27E-04 2.22E-04 1.17E-03 0.00E+00 7.14E-05Benzo(k)fluoranthrene 0.00E+00 1.07E-04 3.26E-05 0.00E+00 6.28E-04

Benzo(a)pyrene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1.51E-04Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

1.12 - Benzoperylene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00




Diluted concentrations of the VOC pollutants 1 metre from the propeller when using

the mineral oil for the two-stroke engine laboratory tests.

Compound






Benzene 5.74E-03 1.51E-02 1.16E-02 1.06E-02 1.49E-02Toluene 1.60E-02 5.05E-02 4.00E-02 3.67E-02 5.21E-02

Ethyl benzene 1.71E-03 7.07E-03 6.17E-03 5.31E-03 7.16E-03o, m-xylenes 5.25E-03 2.04E-02 1.76E-02 1.54E-02 2.10E-02

p-xylene 3.90E-03 1.36E-02 1.16E-02 1.04E-02 1.48E-02C3 benzenes 9.47E-03 5.37E-02 4.79E-02 3.94E-02 5.22E-02C4 benzenes 5.83E-03 3.54E-02 3.33E-02 2.59E-02 3.15E-02Naphthalene 0.00E+00 4.58E-04 4.48E-04 6.39E-04 6.10E-04

Alkyl naphthalenes 0.00E+00 0.00E+00 0.00E+00 1.15E-03 1.37E-03


Diluted concentrations of the VOC pollutants 1 metre from the propeller when using

the EAL for the two-stroke engine laboratory tests.

Compound







Ethyl benzene 3.67E-03 7.56E-03 6.18E-03 4.88E-03 8.67E-03o, m-xylenes 8.95E-03 2.19E-02 1.71E-02 1.37E-02 2.61E-02

p-xylene 6.99E-03 1.59E-02 1.24E-02 1.06E-02 1.75E-02C3 benzenes 2.50E-02 6.91E-02 4.51E-02 3.27E-02 5.60E-02C4 benzenes 9.83E-03 4.54E-02 2.69E-02 1.82E-02 3.11E-02Naphthalene 1.44E-04 7.12E-04 4.29E-04 4.22E-04 9.00E-04

Alkyl naphthalenes 0.00E+00 9.10E-04 0.00E+00 0.00E+00 1.21E-03





the mineral lubricant for the two-stroke engine field tests.

Compound




Naphthalene 1.01E-03 2.55E-03 2.68E-03Acenaphthylene 1.24E-04 0.00E+00 3.21E-05Acenaphthene 0.00E+00 3.01E-05 3.05E-05

Flourene 0.00E+00 0.00E+00 0.00E+00Phenanthrene/Anthracene 1.47E-04 0.00E+00 1.06E-04

Flouranthene 0.00E+00 2.12E-04 9.61E-05Pyrene 0.00E+00 0.00E+00 3.90E-05

Chrysene 0.00E+00 0.00E+00 0.00E+001, 2 - Benzanthracene 0.00E+00 6.51E-04 0.00E+00Benzo(k)fluoranthrene 0.00E+00 7.74E-04 0.00E+00

Benzo(a)pyrene 4.17E-03 0.00E+00 4.10E-05Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00




the EAL for the two-stroke engine field tests.

Compound




Naphthalene 2.31E-03 2.00E-03 3.31E-03Acenaphthylene 7.75E-06 7.92E-06 0.00E+00Acenaphthene 1.41E-04 2.94E-05 3.37E-05

Flourene 0.00E+00 1.15E-05 1.26E-04Phenanthrene/Anthracene 0.00E+00 1.15E-05 1.26E-04

Flouranthene 6.39E-04 1.40E-05 0.00E+00Pyrene 3.44E-03 1.29E-04 1.60E-04

Chrysene 0.00E+00 0.00E+00 0.00E+001, 2 - Benzanthracene 0.00E+00 0.00E+00 0.00E+00Benzo(k)fluoranthrene 0.00E+00 0.00E+00 0.00E+00

Benzo(a)pyrene 0.00E+00 0.00E+00 7.12E-05Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00





Diluted concentrations of the PAH pollutants 1 metre from the propeller for the four-


Compound








Anthracene 0.00E+00 4.71E-05 2.94E-05 3.11E-05 2.85E-05Flouranthene 2.36E-04 3.20E-05 0.00E+00 4.46E-05 1.71E-05

Pyrene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00Chrysene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

1, 2 - Benzanthracene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00Benzo(k)fluoranthrene 0.00E+00 0.00E+00 0.00E+00 1.44E-04 1.98E-04

Benzo(a)pyrene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00Indeno(1,2,3 - C.D)pyrene & 1.2:5.6 - Dibenzanthracene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1.18E-04

1.12 - Benzoperylene 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.26E-04


Diluted concentrations of the VOC pollutants 1 metre from the propeller for the four-


Compound







Ethyl benzene 0.00E+00 4.16E-04 1.71E-04 1.81E-04 1.52E-04o, m-xylenes 0.00E+00 1.61E-04 6.57E-05 7.05E-05 5.91E-05

p-xylene 0.00E+00 8.24E-05 3.52E-05 4.21E-05 3.32E-05C3 benzenes 0.00E+00 2.16E-03 9.77E-04 1.07E-03 8.19E-04C4 benzenes 0.00E+00 1.04E-03 4.54E-04 6.61E-04 4.44E-04Naphthalene 0.00E+00 3.40E-04 2.17E-04 3.32E-04 2.21E-04

Alkyl naphthalenes 0.00E+00 1.16E-03 4.26E-04 6.39E-04 2.45E-04



Appendix D – Two-Stroke Engine Performance Modelling Input Data 183

AAPPPPEENNDDIIXX DD:: TTWWOO--SSTTRROOKKEE EENNGGIINNEE

PPEERRFFOORRMMAANNCCEE MMOODDEELLLLIINNGG IINNPPUUTT DDAATTAA Basic Engine Configuration: Bore: 47mm Stroke: 43mm Connecting Rod: 81mm Gudgeon Pin Offset: 0mm Bore/Stroke Ratio: 1.093 Connecting Rod Length/Stroke Ratio: 1.8837 Reed valve controlled induction. Box muffler exhaust system. Pipe Step Factor: Lower Limit: 1.6 Upper Limit: 6.6 Value: 5.5 Scavenging Parameters: Maximum Short Circuit Ratio: 0.10 Maximum Displacement Scavenging Fraction: 0.90 Scavenge Ratio for Zero Short Circuit: 1.00 Scavenge Ratio for No Displacement Scavenging: 0.40

Box Name Clearance Volume (cc)

Swept Volume (cc)

Compression Ratio

Crankcase 100.30 74.60 7.74 Cylinder 8.5 74.60 6.71

Box Muffler 70.00 - -

Calorific Value of Fuel (btu/lb) Air/Fuel Ratio Throttle Area Ratio

18536.3 11.50 1.000 Combustion Parameters: Combustion Efficiency: 0.85 Burn Period: 60º Ignition Timing: 20º BTDC



Ambient Conditions: Temperature: 20ºC Pressure: 101325 Pascals Piston Port Dimensions:

Port Name

Number of Ports

Bridged (y/n)

Maximum Angular

(deg)

Port Arc

(mm)

Width Chord (mm)

Height (mm)

Corner Top

(mm)

Radii Bottom (mm)

Transfer 2 n 50.47 20.70 20.04 7.01 3.51 3.51 Exhaust 1 - 67.29 27.60 26.04 15.02 7.51 7.51

Port Name Total Area (sq.cm)

Attitude Axial (deg)

Angle Radial (deg)

Transfer 2.5991 15.0 35.0 Exhaust 3.4274 0.0 0.0

Piston Port Timings:

Port Name Start Open

(deg at TDC)

Full Open (deg at TDC)

Start Open (mm from

TDC)

Full Open (mm from TDC)

TRANSFER 118.5 151.2 33.99 41.01 EXHAUST 99.8 180.0 27.98 43.00

Reed Valve Details: Number of Reed Valve Blocks: 1 Reed Block Dimensions

Port Name

Number of Ports

Width (mm)

Length (mm)

Corner Radius (mm)

Stop Plate

Radius (mm)

Block Angle

(degrees)

Inlet 2 10.00 25.00 2.00 65.00 90.00



Reed Petal Details (Uniform Thickness)

Port Name

Width (mm)

Unclamped Length (mm)

Thickness (mm)

Density (kg/m3)

Young’s Modulus (gn/m2)

Natural Frequencies

(hz)

Inlet 15.00 25.50 0.200 7850.0 207.0

255.11 1598.88 4477.13 8772.59

Reed Port Dimensions

Port Name Maximum Port Area (sq.cm)

Restricted Max. Petal Deflection at Tip (mm)

Inlet 4.9313 5.00 Inlet Duct - Note: Section 3 is the inlet duct portion in the reed valve block.

Section Length (mm)

Diameter in (mm)

Diameter out (mm)

Area in (sq.cm)

Area out (sq.cm)

1 31.0 10.1 10.1 0.80 0.80 2 19.0 16.0 16.0 2.01 2.01 3 13.0 16.0 13.8 2.01 1.50

Transfer Ducts (2 separate ducts) Smooth entry to each transfer duct 2 is NOT assumed. Diameters and areas are those of each individual duct in a group.

Section Length (mm)

Diameter in (mm)

Diameter out (mm)

Area in (sq.cm)

Area out (sq.cm)

1 50.0 21.9 21.9 3.77 3.77 Exhaust Duct (single air cooled system) Section 1 leads to a box muffler.

Section Length (mm) Diameter (mm) Area (sq.cm) in out in out

Barrel 19 20 26.9 3.14 5.68 1 19 24.4 26.9 4.68 5.68

Tail Pipe Section

Diameter (mm) Length (mm) Area (sq.cm) 18.2 20.0 2.60



Engine Performance Indicators

Speed Power Torque Power Torque (RPM) (kW) (Nm) (hp) (ft lbf)

500 0.367 7.008 0.492 5.169 750 0.544 6.929 0.73 5.11

1000 0.711 6.787 0.953 5.006 1250 0.855 6.53 1.146 4.816 1500 0.995 6.334 1.334 4.672 1750 1.104 6.022 1.48 4.442 2000 1.214 5.798 1.629 4.277 2250 1.304 5.534 1.748 4.081 2500 1.385 5.289 1.857 3.901 2750 1.464 5.083 1.963 3.749 3000 1.537 4.893 2.061 3.609 3250 1.613 4.738 2.162 3.495 3500 1.684 4.595 2.258 3.389 3750 1.743 4.439 2.338 3.274 4000 1.798 4.292 2.411 3.166 4250 1.844 4.142 2.472 3.055 4500 1.883 3.996 2.525 2.947


Appendix E – Power and Torque Data for the Honda Outboard Engine 187

AAPPPPEENNDDIIXX EE:: PPOOWWEERR AANNDD TTOORRQQUUEE DDAATTAA FFOORR TTHHEE

HHOONNDDAA OOUUTTBBOOAARRDD EENNGGIINNEE

Power vs RPM Curve

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

0 1000 2000 3000 4000 5000 6000RPM

Pow

er (k

W)

Power Curve for the Honda Outboard Engine

Torque vs RPM

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

2500 3000 3500 4000 4500 5000 5500 6000 6500

RPM

Torq

ue (N

m)

Torque Curve for the Honda Outboard Engine

Documents

ANALYSIS OF THE UNDERWATER EMISSIONS … of the Underwater Emissions from Outboard Engines i Abstract The development of Environmentally Adapted Lubricants (EALs) and their use has