Structural Effects of Biodiesel on Soot Volume Fraction in a … · 2015-12-22 · Abstract Structural Eﬀects of Biodiesel on Soot Volume Fraction in a Laminar Co-Flow Diﬀusion

Structural Effects of Biodiesel on Soot Volume Fractionin a Laminar Co-Flow Diffusion Flame

by

Jason Weingarten

A thesis submitted in conformity with the requirementsfor the degree of Masters of Applied Science

Graduate Department of Mechanical and Industrial EngineeringUniversity of Toronto

© Copyright 2015 by Jason Weingarten

Abstract

Structural Effects of Biodiesel on Soot Volume Fraction in a LaminarCo-Flow Diffusion Flame

Jason WeingartenMasters of Applied Science

Graduate Department of Mechanical and Industrial EngineeringUniversity of Toronto

2015

An experimental study was performed to determine the structural effects of biodiesel on soot

volume fraction in a laminar co-flow diffusion flame. These include the effects of the ester

function group, the inclusion of a double bond, and its positional effect. The soot volume frac-

tion and temperature profiles of a biodiesel surrogate, n-Decane, 1-Decene, and 5-Decene fuels

were measured. Improvements were made to existing laser extinction and rapid thermocouple

insertion apparatus and were used to measure soot volume fraction and temperature profiles

respectively. Flow rates of each fuel were determined in order to keep the temperature effects

on soot negligible. Using n-Decane as a baseline, the double bond increased soot production

and was further increased with a more centrally located double bond. The ester function group

containing oxygen decreased soot production. The order of most to least sooting fuels were as

follows 5-Decene > 1-Decene > n-Decane > Biodiesel Surrogate.

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Acknowledgements

First of all I would like to thank my supervisor Murray J. Thomson for his help and guidanceover these past two years. It was a privilege working under his expert supervision. He providedme with enough guidance and scientific knowledge to complete this thesis. I would also liketo thank my committee members Professors Nasser Ashgriz and James S. Wallace for theirvaluable insight. Finally I would like to thank my family for supporting me over the past yearsand my colleagues from the Combustion Research Lab especially, Mohammad Reza Kholghyand Anton Sediako for their help running the experiments and feedback.

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Table of Contents

List of Tables vii

List of Figures viii

1 Introduction 11.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Literature Review 32.1 Soot Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1.1 Fuel Pyrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.1.2 Polycyclic Aromatic Hydrocarbon (PAH) Formation . . . . . . . . . . . . . 52.1.3 Polycyclic Aromatic Hydrocarbon Growth . . . . . . . . . . . . . . . . . . 52.1.4 Soot Evolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1.4.1 Particle Nucleation . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.1.4.2 Particle Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.5 Soot Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.2 Combustion Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.2.1 Emission Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.2.2 Soot Formation in Diesel Engines . . . . . . . . . . . . . . . . . . . . . . . 92.2.3 Diesel Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.3 Alternative Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.3.1 Fischer-Tropsch Diesel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.3.2 Dimethyl Ether . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.3.3 Vegetable Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.3.4 Biodiesel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.3.4.1 Production Process . . . . . . . . . . . . . . . . . . . . . . . . . . . 162.3.4.2 Transesterification Byproducts . . . . . . . . . . . . . . . . . . . . 172.3.4.3 Viscosity Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.3.4.4 Biodegradability . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182.3.4.5 Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182.3.4.6 Engine Performance . . . . . . . . . . . . . . . . . . . . . . . . . . 19

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2.3.4.7 Biodiesel Molecular Characteristics . . . . . . . . . . . . . . . . . . 192.4 Biodiesel Surrogates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3 Experimental Methodology 243.1 Burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243.2 Vaporizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.3 Flame Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

3.3.1 Fuel Flow Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.4 Laser Extinction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.4.1 Laser Extinction Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.4.2 Laser Extinction Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

3.5 Rapid Thermocouple Insertion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283.5.1 Correction for Radiation Heat Losses . . . . . . . . . . . . . . . . . . . . . 30

3.6 Apparatus Improvements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313.6.1 Lock-In Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313.6.2 Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

3.7 Error Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4 Results and Discussion 394.1 Soot Volume Fraction Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.1.1 Biodiesel Surrogate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.1.2 n-Decane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.1.3 Biodiesel Surrogate vs. n-Decane . . . . . . . . . . . . . . . . . . . . . . . . 394.1.4 Decene Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

4.1.4.1 1-Decene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424.1.4.2 5-Decene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

4.1.5 Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434.2 Temperature Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

4.2.1 Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474.2.2 Center Line and Maximum Temperatures . . . . . . . . . . . . . . . . . . . 47

5 Conclusions and Recommendations 515.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515.2 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

5.2.1 Improvements to Methodology . . . . . . . . . . . . . . . . . . . . . . . . . 525.2.2 Future Tests/Comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Bibliography 54

Appendix A Temperature Profiles 65A.1 Inlet Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

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A.2 Surrogate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66A.3 n-Decane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67A.4 1-Decene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68A.5 5-Decene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Appendix B Error Analysis 70B.1 Soot Volume Fraction Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Appendix C MATLAB Code 71C.1 Soot Volume Fraction MATLAB Code . . . . . . . . . . . . . . . . . . . . . . . . 71C.2 Temperature MATLAB Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Appendix D Biodiesel 78D.1 Biodiesel Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78D.2 Biodiesel Flow Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Appendix E Flow Rates 82E.1 Surrogate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82E.2 n-Decane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83E.3 Decene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Appendix F Raw Data 84F.1 Soot Volume Fraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84F.2 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

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List of Tables

Table 2.1: Changes in Particulate Emission Standards for European Union, Japan,and the USA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 2.2: Properties of F-T diesel and No. 2 petroleum diesel fuels. . . . . . . . . . 11Table 2.3: Properties of Dimethyl Ester and No. 2 petroleum diesel fuels. . . . . . . 12Table 2.4: Properties of Vegetable Oils. . . . . . . . . . . . . . . . . . . . . . . . . . . 13Table 2.5: Properties of biodiesel compared with Diesel fuel. . . . . . . . . . . . . . . 14Table 2.6: Major Fatty Acids (weight %) in Some Oils and Fats Used as Alternative

Diesel Fuels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Table 2.7: Average reduction in biodiesel emissions compared to conventional diesel. . 18

Table 3.1: Pressures used for liquids and gasses in the experiment. . . . . . . . . . . 26Table 3.2: Flow rates for each of the fuels tested in the experiment. . . . . . . . . . . 27Table 3.3: Values and error for each component of soot volume fraction. . . . . . . . 36Table 3.4: Sources of error and their values for thermocouple probe measurements. . 37

Table 4.1: Maximum soot volume fraction values for all fuels studied from 40–80mmflame heights. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Table 4.2: Percentage difference between the biodiesel surrogate and Decene fuelsfrom n-Decane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table D.1: Test results of several parameters for B100 biodiesel produced from animalfats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Table D.2: Free acid methyl ester (FAME) composition analysis by gas chromatography. 79

Table F.1: Soot volume fraction data for the biodiesel surrogate fuel. . . . . . . . . . 84Table F.2: Soot volume fraction data for the n-Decane fuel. . . . . . . . . . . . . . . 85Table F.3: Soot volume fraction data for the 1-Decene fuel. . . . . . . . . . . . . . . . 86Table F.4: Soot volume fraction data for the 5-Decene fuel. . . . . . . . . . . . . . . . 87Table F.5: Temperature data for the biodiesel surrogate fuel. . . . . . . . . . . . . . . 88Table F.6: Temperature data for the n-Decane fuel. . . . . . . . . . . . . . . . . . . . 89Table F.7: Temperature data for the 1-Decene fuel. . . . . . . . . . . . . . . . . . . . 90Table F.8: Temperature data for the 5-Decene fuel. . . . . . . . . . . . . . . . . . . . 91

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List of Figures

Figure 2.1: Overview of the soot formation mechanism for a co-flow annular diffusionflame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 2.2: Growth of polycyclic aromatic hydrocarbons through the HACA mecha-nism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 2.3: Transmission electron microscope images of soot particles from a coflowdiffusion flame of a Jet A-1 surrogate showing transparent and fully ma-ture soot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 2.4: Schematic of a diesel soot particle that has undergone coagulation. . . . . 7Figure 2.5: World diesel production and consumption in thousands of barrels per day. 11Figure 2.6: World Biodiesel Consumption (thousand of barrels per day). . . . . . . . 14Figure 2.7: Cetane number (CN) of pure fatty acid methyl esters. . . . . . . . . . . . 15Figure 2.8: A triglyceride molecule consisting of Lauric acid (12:0), Palmitic acid

(16:0), and Myristic acit (14:0) attached to a glycerin molecule. . . . . . . 16Figure 2.9: Simplified Block diagram of the transesterification process to produce

biodiesel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Figure 2.10: Chemical Equation of the transesterification process to produce biodiesel. 17Figure 2.11: Chemical diagrams comparing two typical biodiesel molecules with diesel

fuel highlighting differences. . . . . . . . . . . . . . . . . . . . . . . . . . . 20Figure 2.12: Molecular comparison of the methyl-octanoate/n-Decane surrogate and

the similar methyl esters found in biodiesel. . . . . . . . . . . . . . . . . . 22Figure 2.13: Comparison of n-Decane with 1-Decene and 5-Decene to show the method

of analysing of the double bond and its position. . . . . . . . . . . . . . . 23

Figure 3.1: Schematic of the burner apparatus with the acrylic tube used for laserextinction measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 3.2: Pictures of all four flames studied. . . . . . . . . . . . . . . . . . . . . . . 26Figure 3.3: Schematic of the laser extinction setup. . . . . . . . . . . . . . . . . . . . 29Figure 3.4: Pictures of Rapid Temperature Insertion Setup . . . . . . . . . . . . . . . 29Figure 3.5: Thermocouple measurements for a soot free location (a) and a soot con-

taining location (b) within the flame. . . . . . . . . . . . . . . . . . . . . 30Figure 3.6: Lock in amplifier schematic showing the three main components. . . . . . 32

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Figure 3.7: Comparison of lock in amplifier versus only the photodiode when mea-suring the laser intensity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 3.8: Difference in laser intensities for different chopper frequencies when mea-suring the laser and flame. . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 3.9: Difference in laser intensities for different lock-in amplifier time constantswhen measuring the laser and flame. . . . . . . . . . . . . . . . . . . . . . 33

Figure 3.10: HeNe laser beam path starting at the polarizing beam splitter. . . . . . . 34Figure 3.11: Trend comparison of attenuated and pure laser intensities without polar-

ization for three consecutive radial positions at a height of 70mm in theflame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 3.12: Trend comparison of attenuated and pure laser intensities with polar-ization for three consecutive radial positions at a height of 70mm in theflame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 3.13: Differences in radial position between subsequent tests for maximum tem-perature (a) and soot volume fraction (b). . . . . . . . . . . . . . . . . . . 38

Figure 4.1: Soot volume fraction profiles for the biodiesel surrogate. . . . . . . . . . . 40Figure 4.2: Soot volume fraction profiles for n-Decane. . . . . . . . . . . . . . . . . . 40Figure 4.3: Soot volume fraction profiles comparing the biodiesel surrogate and n-

Decane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Figure 4.4: Soot volume fraction profiles comparing n-Decane at z = 70mm (90%

of total flame height) and the biodiesel surrogate at the correspondingflame height percentage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 4.5: Soot volume fraction profiles for 1-Decene. . . . . . . . . . . . . . . . . . 43Figure 4.6: Soot volume fraction profiles for 5-Decene. . . . . . . . . . . . . . . . . . 44Figure 4.7: Maximum soot volume fraction measured at different vertical heights in

the flame for each fuel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Figure 4.8: Maximum soot volume fraction measured at different vertical heights in




the flame for each fuel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Figure A.1: Temperature profiles for all fuels at the fuel tube inlet. . . . . . . . . . . 65Figure A.2: Temperature profiles with error for biodiesel surrogate. . . . . . . . . . . 66Figure A.3: Temperature profiles with error for n-Decane. . . . . . . . . . . . . . . . . 67Figure A.4: Temperature profiles with error for 1-Decene. . . . . . . . . . . . . . . . . 68

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Figure A.5: Temperature profiles with error for 5-Decene. . . . . . . . . . . . . . . . . 69

Figure E.1: Scale reading of the biodiesel surrogate for a target flow rate of 18.6 g/h. 82Figure E.2: Scale reading of n-Decane for a target flow rate of 16.0 g/h. . . . . . . . . 83Figure E.3: Scale reading of Decene for a target flow rate of 15.8 g/h. . . . . . . . . . 83

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Chapter 1

Introduction

1.1 Motivation

Soot is a term given to the particulates formed during hydrocarbon combustion under fuelrich conditions [1]. Soot is formed mostly as nanoparticles suspended in burned combustiongasses [2] and is produced by the burning of fossil fuels, especially coal, in power-generatingfacilities, as well as by diesel-powered vehicles, aircraft, wood-burning stoves and fireplaces, andthe smelting of metals [3].

Soot contributes greatly to the luminosity of the flame [4]. The bright yellow incandescencein flames indicate the presence of microscopic soot particles that are formed and transported bythe combustion gases which consists primarily of micron-sized, fractal aggregates of 20-50 nmnanoparticle spheres [5]. In large flames, soot can be used as a radiating agent to promote heattransfer [1]. In addition, black soot is used as a filler for elastomers as well as copy machinesand laser printers [6]. However with internal combustion engines, particularly diesels, it canfoul exhaust systems and generate dark exhaust plumes [1]. Soot particles primarily from fossilfuel combustion, show increased mortality due to respiratory and cardiovascular disease [7], area major factor in global warming due to the greenhouse effect [8], and decreases atmosphericvisibility [9].

The U.S. Congress passed the Clean Air and Air Quality Acts in which put a limit on theamount of particulates particulates smaller than 2.5 µm (PM2.5) allowed in the air both dailyand annually to improve air quality. Throughout the years they have constantly reduced theamount of allowed particulate emissions in vehicle exhaust. In 1997 the standards were set ata level of 15 µg/m3 of annual mean PM2.5 concentrations and 65 µg/m3 daily. In 2006, EPAreduced the daily amount to 35 µg/m3, and retained annual PM2.5 at 15 µg/m3. Most recentlyin 2012 the annual fine particle standard was lowered from the current level of 12 µg/m3 [10].Similar laws were also adopted in other countries creating a need to constantly improve thecombustion process and fuel to reduce the amount of soot created.

Over the past decade public interest in using biodiesel has grown significantly. This intereststems from the fact that biodiesel is renewable, domestically produced and can reduce partic-

1

Chapter 1. Introduction 2

ulate emissions when blended with traditional diesel [11]. Biodiesel is a fuel which is typicallyderived from a variety of vegetable oils and animal fats [12] and consists of a mixture of fattyacid methyl esters with exact amounts depending on the source oil or fat. Biodiesel has twomain molecular differences when compared to conventional diesel which are the inclusion of adouble bond at different positions along the FAME molecule, and an ester function group whichcontains an oxygen atom. In addition, biodiesel contains no aromatic compounds unlike diesel.

Biodiesel, like other oxygenated diesel fuels, can reduce the amount of soot formed in thecombustion process and can lead to reduced total particulate emissions. In addition, the sootproduced is more reactive toward oxidation [13] which is provided by the ester function group.However the double bond present in the methyl ester has the opposite effect. High-pressureshock tube studies on the oxidation of methyl-octanoate and methyl-octenoate showed thatthere is a correlation between increased soot formation and the presence of carbon-carbondouble bonds in the ester structure [14]. In addition, for methyl esters with the same carbonnumber, studies showed the exact position of the double bond appears to have only a slightimpact on the amount of soot produced [15]. Furthermore, there is a reduction in particulatematter when using biodiesel instead of regular diesel due to the aromatic compounds that arepresent in regular diesel but are absent in biodiesel fuels [16].

The study of soot in laminar co-flow diffusion flames is important to better understand theprocess [17]. Diffusion flames are simpler versions of more complex flames while still containingall of the soot production processes and are much simpler to model numerically over turbulentflames of the same fuel. Of the past studies performed on biodiesel no detailed studies have beendone which look at the effect of soot production for all of the different molecular differences.

1.2 Objectives

The main objective of this work is to study the structural effects of biodiesel on soot volumefraction in a laminar co-flow diffusion flame. These include the effects of an ester function group,the inclusion of a double bond, and the positional effect of the double bond. This was doneby measuring both the soot volume fraction and temperature profiles of a biodiesel surrogate(50% n-Decane 50% methyl-octanoate by mole), n-Decane, 1-Decene, and 5-Decene fuels. Thesoot volume fraction profiles were measured using a laser extinction method, while temperatureprofiles were measured using a rapid thermocouple insertion method. In order to determinethe effect of the ester function group n-Decane will be used as a baseline compared with thebiodiesel surrogate. The effect of the double bond is determined by comparing n-Decane with 1-Decene, and 5-Decene to further analyze the effect of its position. Before taking measurementsadditional improvements were made to both experimental methods. These included adding achopper and lock-in amplifier to improve the signal to noise ratio, and polarization of the laserto allow for better soot volume fraction measurements.

Chapter 2

Literature Review

2.1 Soot Formation

The idea that carbon particles were the cause of flame luminosity due to the splitting ofacetylene into hydrogen and carbon was initially proposed in the 1800s [18]. Since then there hasbeen much interest in understanding the process of soot formation. Most hydrocarbon diffusionflames are luminous, and this luminosity is due to carbon particulates that radiate strongly atthe high combustion gas temperatures [19]. When examined under an electron microscope,carbon deposits appear to consist of aggregates of roughly spherical particles whose diametersvary most commonly from 10 nm to 50 nm [20]. The overall process of soot formation consistsof six major processes [21]:

1. Fuel pyrolysis or the initial decomposition of the hydrocarbon fuel.

2. Polycyclic aromatic hydrocarbon (PAH) Formation, which includes the formation of thefirst aromatic ring from open carbon chains.

3. PAH Growth through a two step Hydrogen-abstraction-C2H2-Addition (HACA) process.

4. Particle Nucleation consisting of coalescence of PAH into three dimensional clusters.

5. Particle Growth through coagulation, surface reactions, carbonization, and agglomeration.

6. Soot Oxidation where the soot particles lose mass and size before exiting the flame.

Figure 2.1 shows all of the possible mechanisms of soot formation at different stages startingwith soot inception, followed by particle growth and finally oxidation. The entire process ofsoot formation starting with the formation of the first aromatic ring, mass growth, and finallyaggregating into fractal structures involves many fast parallel reactions all of which occur oververy short periods of time, typically within a few milliseconds. Because of this, the entire sootformation mechanism is still not completely understood [2, 6].

3

Chapter 2. Literature Review 4

Figure 2.1: Overview of the soot formation mechanism for a co-flow annular diffusion flame[22].

2.1.1 Fuel Pyrolysis

The initial step in the formation of soot from a hydrocarbon regardless of flame type is thepyrolysis of the fuel [19]. The large fuel hydrocarbons break down into smaller fuel fragmentsin the presence of high temperature. The rate that a fuel decomposes is strongly dependant onthe temperature as well as the concentration [23].

Fuel pyrolysis results in the production of some species which are soot precursors or thebuilding blocks for soot. The formation of soot precursors is a competition between the rate ofpure fuel pyrolysis and the rate of fuel and precursor oxidation by O2 and OH radicals. Bothpyrolysis and oxidation rates increase with temperature, but the oxidation rate increases faster.This explains why premixed flames (where some amount of oxygen is present) soot less anddiffusion flames (no oxygen is present in the pyrolysis region) soot more as the temperatureincreases [23].


2.1.2 Polycyclic Aromatic Hydrocarbon (PAH) Formation

Once a fuel undergoes pyrolysis it is reduced into several smaller species mainly: unsaturatedhydrocarbons, polyacetylenes, polycyclic aromatic hydrocarbons and acetylene [23]. In the caseof fuels that already contain aromatics, PAHs are formed in relatively large concentrationsduring the decomposition of the fuel. However, in the case of aliphatic fuels such as acetylene,ethylene or methane, the first aromatic ring must be formed from fuel decomposition productsby a sequence of elementary reactions [24]. It is believed that polycyclic aromatic hydrocarbonsare the key intermediate compounds in soot formation [6]. The formation of the first aromaticring from small aliphatics is the primary focus in soot because it is perceived to be the rate-limiting step in the reaction sequence to form larger aromatics [25].

2.1.3 Polycyclic Aromatic Hydrocarbon Growth

The tendency to produce soot is determined by the initial rate of formation of the first andsecond PAH ring structures. The processes of growth to even larger aromatic ring structuresleading to soot nucleation and growth are similar for all fuels and faster than the formation ofthe initial rings [19]. Therefore, the slow formation of the initial aromatic rings controls thesoot formation rate, which determines the amount of soot formed.

After the first aromatic ring is formed it continues to grow through H-abstraction-C2H2-addition or the HACA process shown in Figure 2.2. HACA growth is a repetitive reactionsequence of two principal steps (i) abstraction of a hydrogen atom from the reacting hydrocarbonby a gaseous hydrogen atom followed by (ii) addition of a gaseous acetylene molecule to theradical site formed [25]. The conversion of the hydrocarbon into a radical can be accomplishedin many different ways. Experimental analysis has shown that H-abstraction by a gaseous Hatom typically dominates as the growth mechanism [25].

2.1.4 Soot Evolution

As PAHs continue to grow, several parallel processes occur which converts the aromaticsinto larger soot particles. These processes are particle nucleation, and particle growth whichencompasses surface reactions, coagulation, agglomeration, and carbonization.

2.1.4.1 Particle Nucleation

Nucleation or soot particle inception is the formation of particles from gas-phase reactants[23]. As the PAH continues to grow, they agglomerate into clusters and develop into a sootparticle nuclei know as a primary particle. Studies of particle inception temperatures showthat nucleation occurs in regions of the flame that are between 1300–1600K. An examinationof soot in a laminar coflow diffusion flame of Jet A-1 surrogate show that certain particlesproduced along the centerline do not absorb visible light, are fairly transparent, and appear tobe liquid like [27]. These liquid like particles are shown in Figure 2.3 where particle samples


C

C

C

C

C

C

C

C

H(-H2)

H

C2H2(-H)

H

H

H

H

H

C2H2

C2H2

C2H2(-H) C2H2(-H)

H(-H2)

C2H2(-H)Large PAHs

Figure 2.2: Growth of polycyclic aromatic hydrocarbons through the HACA mechanism [26].

were taken at different heights along the centerline. These particles are widely considered to bethe precursor stage to the more commonly observed carbon aggregates [28] and tend to occurat flame position where the temperature is <1500K.

Figure 2.3: Transmission electron microscope images of soot particles from a coflow diffusionflame of a Jet A-1 surrogate showing transparent and fully mature soot [29].

2.1.4.2 Particle Growth

Surface growth is the process of adding mass to the surface of a primary soot particle.There is no clear distinction between the end of nucleation and the beginning of surface growthmaking the two processes occur simultaneously [23]. During surface growth, the hot reactivesurface of the soot particles combines with gas-phase hydrocarbons, which appear to be mostlyacetylenes. This results in an increase in the mass of the soot particle while the number ofparticles remains constant [23].


The majority of the soot mass is added during surface growth meaning the residence timeof the surface growth process has a large influence on the total soot mass or soot volumefraction. Surface growth rates are higher for small particles than for larger particles becausesmall particles have more reactive radical sites [30].

In addition to surface growth, there are two other methods of particle growth. Coagulationand agglomeration are both processes in which soot particles collide and combine together.Soot coagulation also known as coalescence occurs when particles collide and form a singlelarger particle, which are “glued” together by a common outer shell [31]. This results in adecrease in the number of particles while holding the combined mass of the two soot particlesconstant. During coagulation, two roughly spherically shaped particles combine to form a singlespherically shaped particle shown in Figure 2.4.

The structure of soot particles were initially studied in Acetylene [32], Benzene [33] andPropane [34] flames using light scattering methods and electron microscope analysis. It wasfound that coagulation of carbon particles occurs at all positions in the flame. The coagulationprocess combined with surface growth to form particle clusters that gradually change fromroughly spherical, at early and intermediate stages of growth, to chain-like in the later stages.These differences in the particle structure classifies soot into two different types known asincipient soot or soot precursors and mature soot.

a) b)

Figure 2.4: Schematic of a diesel soot particle that has undergone coagulation [31, 35].

Experiments have found that the coagulation process occurs almost immediately after thesoot particle formation, or when soot particles are relatively small or young [36]. Soot ag-glomeration takes place in the late phase of soot formation when, due to lack of surface growth,coagulation is no longer possible [31]. During the agglomeration process the primary soot parti-cles stick to each other, forming chain-like aggregate structures consisting of the basic sphericalparticles [6].

Carbonization is the irreversible physical and chemical transformation of coalesced materialtoward solid soot. The carbonization process is characterized by a loss of hydrogen in the


soot and occurs during and after coagulation and agglomeration [37]. This process convertsthe liquid-like soot into a progressively more graphitic carbon material, with some decrease inparticle mass but no change in particle number. Due to the reduction in the number of activesites on the soot particles for surface growth, the carbonization process leads to the formationof chain-like, open structured aggregates, containing 30-1800 primary particles [38].

2.1.5 Soot Oxidation

In a flame, the soot particles are eventually transported into a region where oxidative speciesare present [39]. Oxidation is the conversion of carbon or hydrocarbons to combustion products.Oxidation occurs primarily as a result of attack by molecular oxygen, O2, and the OH radical.Other oxygenated species such as the O atom, H2O and CO2 may be important under someconditions [40]. Once carbon has been partially oxidized to CO, the carbon will no longer evolveinto a soot particle even if entering a fuel-rich zone [23]. If soot oxidation is complete, no sootis emitted from the flame [39]. Oxidation can take place at any time during the soot formationprocess from pyrolysis through agglomeration [23]. Unlike the soot growth process, in whichatoms are added to the particles, the soot oxidation depletes the carbon mass accumulated inthe soot particles [36].

2.2 Combustion Engines

Diesel engines work on a fundamentally different process than spark ignition engines. Whilea spark ignition engine injects fuel into an engine cylinder, it allows for the fuel to vaporizeand mix with the air to produce premixed conditions where a spark ignites the mixture. Adiesel engine injects fuel under high pressure into the chamber where the droplets begin toevaporate and the fuel vapour mixes with air. Portions of the fuel-air mixture autoignite andinitiate nonpremixed combustion. Therefore combustion in a diesel engine takes place in bothpremixed and diffusion modes [41]. The main advantage of the diesel engine is that it has ahigher efficiency than a spark ignition engine with the highest efficiency being 45% and 30%for compression and spark ignition engines respectively [42].

The particulate formation and oxidation processes in spark ignition engines have not beenstudied as well as in diesel engines [43]. Studies of particulate matter has shown that sparkignition engines can emit a significant number of particulates in comparison with compressionignition engines. However, these are in the ultra-fine-particle and nanoparticle range, comparedwith the larger particles from compression ignition engines [44].

2.2.1 Emission Standards

The USA, EU and Japan are the three countries that are leading the way in air qualitystandards and policies for limiting particulate emissions (PM2.5) from vehicles. Table 2.1 showsthe changes in average allowable particulate emissions since the standards came into effect.


Different measurement systems are used across the world with the USA measuring the con-centration of particulates in exhaust gas while other countries measure the mass per distancethe vehicle travels. However the USA will start to use mass per distance in future standards.In addition, the current USA limits encompass all fuels while other countries divide the limitsbetween diesel and gasoline engines. However in more recent years the limits on particulateemissions have been the same for all fuel types.

Table 2.1: Changes in Particulate Emission Standards for European Union, Japan, and theUSA (Data gathered from [10],[45]).

Year EU Japan USADiesel(g/km)

Gasoline(g/km)

Diesel(g/km)

Gasoline(g/km)

All Fuels(µg/m3)

1992 0.14 0.14 - - -1996 0.08 0.14 - - -1997 - - - - 152000 0.05 0.14 - - -2002 - - 0.052 - -2005 0.025 0.14 0.014 - -2006 - - - - 152009 0.005 0.005 0.008 0.005 -2012 - - - - 122014 0.005 0.005 - - -2015 0.0045 0.0045 - - -

One important limit that has only recently been adopted by the EU and recommended tothe USA [46] is number of particles in exhaust. This is especially important when comparinggasoline and diesel since the total contribution of particulates of both spark ignition vehiclesthan diesel-fuelled vehicles could be similar [47]. This means that while the mass of particles arethe same, we may breathe in more harmful particles from spark ignition vehicles due to theirsmaller size particulates. Studies have shown that gasoline-fuelled vehicle PM2.5 contributionexceeded the contribution from diesel vehicles by approximately a factor of 3 [48].

2.2.2 Soot Formation in Diesel Engines

Most diesel engines emit less carbon monoxide and unburned hydrocarbons than comparablespark ignition engines [49]. Due to the non-premixed nature of the combustion process moreparticulate matter is produced in a compression ignition engine. The entire combustion processof a diesel engine is very complex and its detailed mechanisms are not well understood. Whenfuel is injected into the engine, autoignition occurs at locations where the fuel mixture iscombustible. Under most engine operating conditions, ignition starts while some portion ofthe fuel has not yet been injected. The distribution of the fuel within the combustion spacehas a great effect on the mechanisms of combustion and emission formation. This distributiondepends mainly on the injection process and the air motion [49].


Primary particles that coagulate into large aggregates are not necessarily found in dieselexhaust gasses. Their concentration strongly depends on the temperature and time the particlesspend in the oxidizing medium. Therefore only a few thousandth of the initially formed mass ofsoot is not completely oxidized and enter the diesel exhaust gasses [6]. The amount of oxidationthat occurs depends upon the oxygen concentration in the vicinity of the surface of the sootparticles, temperature, and residence time [49]. In addition, soot emissions from diesel enginescan also be influenced by the atomization and configuration of the spray, the method of airsupply, turbulence level, pressure, injection time, and ignition delay [50].

2.2.3 Diesel Fuel

Diesel engines power much of the worlds equipment, are used in many heavy trucks, buses,tractors [51], are becoming popular in passenger vehicles in Europe [52] and gaining popularityin USA [48]. Figure 2.5 shows the current world diesel fuel production and consumption inbarrels per day. There has been a small increase over the past decade however over the pastcouple of years diesel production and consumption has become stagnant. Traditionally, dieselengines run on petrodiesel, which is produced by distilling crude oil extracted from bedrock.A good diesel fuel is characterized by low sulphur and aromatic content, good ignition quality,good cold weather properties, low pollutant content, and the right density, viscosity, and boilingpoint [42]. The usage of conventional petrodiesel fuel is already quite well investigated and theproblems related mainly to NOx and PM emissions are very well known. With a limited supplyof oil reserves and the need to reduce emissions, the usage of alternative fuels has been studiedto either replace or blend with traditional diesel [53]. The evaluation of alternative fuels shouldkeep into account the need to limit emissions, production cost, and keep the same physicalproperties and energy output as current petrodiesel.

2.3 Alternative Fuels

Although there are solutions to reducing particulate matter in engines through reformedexhaust gas recirculation, selective catalytic reduction, and diesel particulate filters alternativefuels provide chemical and physical characteristics that can contribute to lower emissions [55].There are four alternative fuels that can be easily implemented in conventional compressionignition engines. These are: Fischer-Tropsch (F-T) diesel, dimethyl ether (DME), vegetableoil, and biodiesel [42].

2.3.1 Fischer-Tropsch Diesel

In 1923, Fischer and Tropsch discovered the production of liquid hydrocarbons from syn-thesis gas (CO + H2) with the aid of catalysts [56]. Originally synthesized from coal, the F-Tconversion process can be used to create diesel fuels natural gas, and biomass in addition to


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2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

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World Production

World Consumption

Figure 2.5: World diesel production and consumption in thousands of barrels per day [54].

traditional coal [42]. The F-T synthesis is described by the overall reaction equation:

nCO+ (n+m/2)H2 −−→ CnHm + nH2O (2.1)

Where n is the length of the hydrocarbon chain and m is the number of hydrogen atomsper carbon. Table 2.2 shows the comparison of synthetic Fischer-Tropsch diesel versus regularpetrodiesel.

Table 2.2: Properties of F-T diesel and No. 2 petroleum diesel fuels [57].

Property Fischer-TropschDiesel

No. 2Petroleum Diesel

Density, g/cm3 0.7836 0.832HHV, MJ/kg 47.1 45.77 [58]Aromatics, % 0-0.1 8-16Cetane Number (CN) 76-80 40-44Sulphur Content, ppm 0-0.1 <15 [59]

Fischer-Tropsch diesel fuel is characterized by a high cetane number, a near-zero sulphurcontent and a very low aromatic level. In addition, F-T diesel fuel can be used without anyengine modifications. Experiments have shown that the use of FT diesel over regular dieselin test trucks can reduce particulate matter by an average of 24-26% [60]. Additional studiesreported that the CO, HC, NOx, smoke emissions from an unmodified diesel engine operatingon F-T diesel fuel were reduced simultaneously when compared with those of conventional diesel


fuel operation. Smoke emissions in particular were reduced by 40.3% with F-T diesel fuel [61].The main problem with F-T diesel is that the lubricity is poor due to its low aromatic contentand sulphur, but this can be improved with additives [62].

2.3.2 Dimethyl Ether

Dimethyl Ether is a new fuel which has attracted much attention recently. Today DME ismade from natural gas but can also be produced from coal or biomass [42]. Dimethyl ether isthe simplest ether, with a chemical formula of CH3OCH3 and its physical properties are similarto those of liquefied petroleum gases. It is produced in a two step process where syngas is firstconverted to methanol, then to its final product [63]. Its net chemical reaction is:

3H2 + 3CO −−→ CH3OCH3 + CO2 (2.2)

A major advantage of DME is its naturally high cetane number, which means that self-ignition will be easier. The high cetane rating makes DME most suitable for use in dieselengines however the energy content of DME is lower than in diesel. Table 2.3 shows thecomparison of Dimethyl Ether with traditional diesel fuel.

Table 2.3: Properties of Dimethyl Ester and No. 2 petroleum diesel fuels.

Property Dimethyl Ether [58] No. 2Petroleum Diesel [42]

Density, g/cm3 0.661 0.832HHV, megaJ/kg 31.68 45.77 [58]Cetane Number (CN) >55 40-44Sulphur Content, ppm 0 <15 [59]

DME can be used directly as a fuel when mixed with methanol, or as a fuel additive todiesel. DME can be used as an ultraclean alternative fuel for diesel engines. Studies haveshown that diesel mixed with 20 wt% DME there is a 70% reduction in smoke [64]. Theadvantages of using DME are ultralow emissions of nitrogen oxides, reduced engine noise orquiet combustion, virtually soot-free which means there is no need for exhaust after treatment,and high diesel thermal efficiency [63].

The main disadvantage of using DME as a fuel is the lower energy density which means aDME fuel storage tank must be twice the size of a conventional diesel fuel tank. In addition,the viscosity of DME is lower than that of diesel by a significant amount causing an increasedamount of leakage in pumps and fuel injectors. There are also lubrication issues with DMEwhich results in early failure of pumps and fuel injectors [63].


2.3.3 Vegetable Oil

Vegetable oil as an alternative fuel is renewable and a potentially inexhaustible source ofenergy. The energy content is similar to that of regular diesel fuel with many possible sources.Table 2.4 shows properties of several vegetable oils compared with pure diesel. It is seen thatthe cetane number of vegetable oils varies from 37-40 with some vegetable oils reaching as highas 44 [65] which are not significantly lower than diesel.

Table 2.4: Properties of Vegetable Oils [65].

Vegetable Oil Kinematic Viscosityat 38 ◦C (mm2/s) Cetane No. Heating Value

(MJ/kg)Density(kg/L)

Corn 34.9 37.6 39.5 0.9095Rapeseed 37 37.6 39.7 0.9115Sunflower 33.9 37.1 39.6 0.9161Sesame 35.5 40.2 39.3 0.9133Diesel 3.06 40-44 41.6 0.832

Vegetable oils are extremely viscous due to their molecular weight with viscosities rangingfrom 10 to 20 times higher than petrodiesel fuel [65]. Because of this, vegetable oils do notburn completely and form deposits when used directly in diesel engines. However, vegetableoils contain lower sulphur content, aromatic content, and are biodegradable [42]. Studies usingfour different vegetable oils at 10 and 20% blends with regular diesel observed that the amountof % soot emitted by all vegetable oil blends is lower than the ones for the corresponding neatdiesel fuel, with the reduction of soot being greater at the higher percentage blend [66].

2.3.4 Biodiesel

Biodiesel is a fuel consisting of long chain fatty acids derived from renewable feedstocks suchas vegetable oils, recycled cooking grease, or animal fats for use in diesel engines [67]. Biodieselis compatible with conventional diesel and can be used as a complete alternative or blended inany proportion however it is most commonly blended at 20% biodiesel 80% conventional diesel(B20) [51]. Figure 2.6 shows the world production and consumption of biodiesel. Althoughthe amount is significantly smaller than conventional diesel, the technology and production iscontinuously growing. In addition, Table 2.5 compares properties of biodiesel and conventionaldiesel fuel. The heating value for biodiesel is slightly lower than conventional diesel howevermost other properties are similar or better.

Biodiesel must follow the international biodiesel standard specifications provided by Ameri-can standard for testing materials (ASTM) and European Union (EU) standards for alternativefuels. These set limits to important properties such as the viscosity, cetane number, and acidnumber. Biodiesel with a high acid number may result in the severe operational problems suchas engine deposits, filter clogging, or fuel deterioration and can also cause corrosion duringstorage. The acid number is also an important indicator of the degradation or age of biodiesel


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World Biodiesel Production and Consumption

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Figure 2.6: World Biodiesel Consumption (thousand of barrels per day) [54].

as it becomes more acidic the longer it is unused [68].

Table 2.5: Properties of biodiesel compared with Diesel fuel.

Property Biodiesel No 2. DieselDensity, g/cm3 0.86-0.90 0.832HHV megaJ/kg 39-41 45.77Cetane Number (CN) 47 min 40-44Sulphur Content, ppm 0 <15

Another indicator which affects both chemical and physical properties of biodiesel is theiodine number. The iodine number is often used to determine the amount of unsaturation ofthe fuel, or how many double bonds there are. The more unsaturated the biodiesel is the higherthe iodine number, and the more double bonds present. Table 2.6 outlines the major fatty acidpercentages of several biodiesel sources with vegetable oils which are usually less saturated thananimal fats, having a larger percent of double bonds. Over 1000 fatty acids are known, but 20 orless are encountered in significant amounts in the oils and fats used in biodiesel production withthe most common acids being Oleic (18:1) and Linoleic (18:2) [69]. The amount of unsaturationof biodiesel fuels was found to have significant effects on particulate emissions. As the biodieselbecomes more unsaturated it produces more soot precursors and has a greater tendency to sootthan saturated biodiesel [70].

The cetane number of biodiesel can be affected by various parameters including the oilprocessing technology, climatic conditions where the feedstock is collected, and the percentage


Table 2.6: Major Fatty Acids (weight %) in Some Oils and Fats Used as Alternative DieselFuels [71].

Oil or Fat IodineValue

PalmiticAcid

StearicAcid

OleicAcid

LinoleicAcid

LinolenicAcid

Carbons 16 18 18 18 18Double Bonds 0 0 1 2 3Canola 110-126 3.6 1.5 61.6 21.7 9.6Corn 103-140 11.7-14.5 1.4-2.6 22-32.3 52.2-61.7 <1Palm 35-61 44.1 4.4 39 10.6 <1Peanut 86-107 10.8-14.2 2.1-3.3 36.4-67.1 13-43 <1Tallow (beef) 35-48 29.5 26 34.9 1.5 <1

of different methyl esters present in the original feedstock [72]. The chemical structure ofthe FAMEs contributes significantly to the cetane number. The amount of saturation, chainlength, and branching of the fatty compounds have also been found to influence the CN tovarying degrees [73]. As the biodiesel increases the number of double bonds and their positionin the chain the CN will decrease [74]. The effect of cetane number by specific methyl esters isshown in Figure 2.7.

0

10

20

30

40

50

60

70

80

90

Lauric

(12:0)

Myristic

(14:0)

Palmitic

(16:0)

Palmitoleic

(16:1)

Stearic

(18:0)

Oleic

(18:1)

Linoleic

(18:2)

Linolenic

(18:3)

Ce

tan

e N

um

be

r

Fatty Acid Methyl Ester

Figure 2.7: Cetane number (CN) of pure fatty acid methyl esters [75].

The major drawbacks inhibiting commercial production of biodiesel include the cost ofraw materials, the presence of free fatty acids, and water in the oils. The presence of watermolecules reduces the catalytic effectiveness while free fatty acids lead to the formation of soapwhen during biodiesel production [76]. Generally the cost of raw materials accounts about70-80% of the total production cost of biodiesel. Currently, about 84% the world biodieselproduction is met by rapeseed oil. The remaining portion is from sunflower oil (13%), palm


oil (1%) and soybean oil and others (2%) meaning more than 95% of the worlds biodiesel ismade from edible oil [77]. By converting edible oils into biodiesel, food resources are actuallybeing converted into fuel. A study on the feasibility of using edible oils as a biodiesel sourcebelieved that large-scale production of biodiesel may bring global imbalance to the food supplyand demand market [77].

The purity and quality of biodiesel fuel can be significantly influenced by numerous factorsamongst others include: the quality of feedstock, fatty acid composition of the vegetable oils,animal fats and waste oils, type of production and refining process used, and post-productionparameters [77].

2.3.4.1 Production Process

In general, animal fat and vegetable oil consist of 85-95% triglycerides [78]. Triglyceridesare molecules composed of three long fatty acid chains attached to a single glycerin molecule.An example of a triglyceride is shown in Figure 2.8.

Figure 2.8: A triglyceride moleculte consisting of Lauric acid (12:0), Palmitic acid (16:0), andMyristic acid (14:0) attached to a glycerin molecule [79].

Biodiesel can be made through several processes however the most commonly used technol-ogy is the transesterification [67]. Transesterification is the process of using an alcohol in thepresence of a catalyst to break the molecule of the raw renewable oil chemically into methylor ethyl esters of the renewable oil, with glycerol as a by-product [80]. A simplified processdiagram is shown in Figure 2.9 while the chemical equation is shown in Figure 2.10.

During the transesterification reaction triglycerides are first reduced to diglycerides. Thediglycerides are subsequently reduced to monoglycerides which are finally reduced to fatty acidesters [67]. A study of the yield % of crude and refined vegetable oils as feedstocks found thatthe yield of methyl esters for refined vegetable oil from 93-98% and crude vegetable oil yielded67-86% [81]. As for other feedstocks depending on the catalyst, alcohol, and molar ratios at


Transesterification Reactor

Methanol Source Oil or Fat

Catalyst

Glycerin Biodiesel

Figure 2.9: Simplified Block diagram of the transesterification process to produce biodiesel.

different temperature transesterification normally yields between 80 and 95% [82].

C

CH OOR′′

H

CH OOR

H

OOR′H

Triglyceride

+ 3CH3OH

Alcohol

Catalyst C

CH OH

H

CH OH

H

OHH

Glycerin

+ R′OCH3

ROOCH3

R′′OOCH3

Biodiesel

Figure 2.10: Chemical Equation of the transesterification process to produce biodiesel.

2.3.4.2 Transesterification Byproducts

The European Union standard specifications for biodiesel limits the amount of fuel watercontent, free fatty acids, and free bound glycerine requiring the final product to be at least96.5% pure [83]. There are many secondary products produced from transesterification whichcan consist of soap, diglycerides, monoglycerides, glycerol, alcohol, and catalyst all in differentconcentrations. Glycerol, a major byproduct must be sold in order to make biodiesel costeffective. As a result it is sold to various commercial manufacturing industries such as cosmetic,food, tobacco, and pharmaceutical industries [76].

2.3.4.3 Viscosity Effects

Since viscosity is one of the most important properties of a fuel it is an important factorin biodiesel specifications. When using biodiesel as a fuel the viscosity can have a significantimpact on the operation of fuel injection equipment, particularly at lower temperatures wherean increase in viscosity affects the fluidity of the fuel [84]. In addition, having a higher viscosity


leads to poorer atomization of the fuel spray and which affects the operation of fuel injectors[85]. The conversion of triglycerides into methyl or ethyl esters through the transesterificationprocess reduces the viscosity by a factor of about eight [84].

2.3.4.4 Biodegradability

Biodegradable fuels such as biodiesels have an large range of potential applications andare environmentally friendly. Biodiesel is non-toxic and degrades about four times faster thanpetrodiesel mainly due to its oxygen content [86]. Studies on the biodegradation of biodieselcompared with conventional diesel demonstrated that all biodiesels tested degraded between80.4 and 91.2% after 30 days, whereas the diesel sample reached only 24.5% biodegradation[87].

Studies of a polymer additive that is nontoxic, rapidly biodegrades, and does not have anadverse impact on the environment has shown to reduce the acid number of biodiesel blendswhich results in improved fuel quality [88]. Additional studies have looked at the productionof biodegradable lubricant base fluids from biodiesel esters. These lubricants can have prop-erties such as high viscosity index and good oxidation stability and are produced safer, moreeconomical and more efficient than other lubricants [89].

2.3.4.5 Emissions

Biodiesel is said to be carbon neutral so it contributes no net carbon dioxide or sulphurto the atmosphere and emits less gaseous pollutants than normal diesel. In addition, carbonmonoxide, aromatics, PAHs, and partially burned or unburned hydrocarbon emissions are allreduced in vehicles operating on biodiesel [90]. Table 2.7 outlines the average reduction of purebiodiesel and B20 emissions compared to conventional diesel. A life cycle analysis done onbiodiesel [91] showed that substituting 100% biodiesel for petroleum diesel in buses reduces thelife cycle consumption of petroleum by 95%. Also, when using B20 the life cycle consumptionof petroleum drops 19%. Similar results were found for net emissions of CO2 in which B100 andB20 biodiesel blends reduce the net emissions by 78.45% and 15.66% compared to petroleumdiesel respectively. Additional measurements were made of exhaust emissions where particulatesless than 10 µm in size were 67% lower for buses running on biodiesel compared to conventionaldiesel [91].

Table 2.7: Average reduction in biodiesel emissions compared to conventional diesel [92].

Emission Type B100 B20Particulate Matter -47% -12%Total Unburned Hydrocarbons -67% -20%PAH -80% -30%NOx +10% +2% to -2%

A study on the effect of different biodiesel blends on particulate and PAH emissions for


different size ranges showed a reduction in all sizes when compared to conventional diesel. As theblending fractions of biodiesel increased, the PM emissions for coarse (1.8–10 µm), fine (0.32–1.8 µm), ultrafine (0.056–0.32 µm), and nano (0.01–0.056 µm) particle size ranges decreased.The reductions were significant especially for ultrafine and fine particulate matter reductionwith the reduction percentages reaching 45.1% and 63.7% for B60, 66.5% and 68.3% for B100,respectively in ultrafine and fine size ranges [93].

2.3.4.6 Engine Performance

Studies have reported that biodiesel fuels have improved lubrication characteristics, but cancontribute to the formation of deposits, plugging of filters, depending mainly on degradability,glycerol content, cold flow properties, and on other quality specifications [94]. This lubricationproperty help in improving the fuel injectors and fuel pumps lubrication capacity. Biodieselreduced long term engine wear in test diesel engines to less than half of what was observed inengines running on current low sulphur diesel fuel [86]. Studies of increased lubricity reportedthat even biodiesel levels below 1% can provide up to a 30% increase in lubricity [95]. Ingeneral, biodiesel does not cause any loss of power unless the engine is running at its maximumpower. Most of the published literature report some decrease in rated power proportional tothe difference in heating values. However, increased fuel consumption would compensate forthe lower heating value of biodiesel compared with diesel fuel [94].

2.3.4.7 Biodiesel Molecular Characteristics

As stated previously, biodiesel is made up of many methyl esters however most are similarin structure. Diesel fuel is significantly different, with the main components in diesel fuelbeing n-alkanes, iso-alkanes, cycloalkanes and aromatics [96]. Biodiesel has two main moleculardifferences when compared to conventional diesel which are the inclusion of a double bond andan ester function group. In addition, biodiesel fuel contains no aromatic compounds howeveraromatics comprise a large fraction of diesel (about 30-35% by weight on average) [96]. Whilediesel fuel may contain thousands of compounds, biodiesel fuels typically contain fewer thanten [97]. Figure 2.11 shows the differences between both diesel and biodiesel molecules.

The oxygen content of the biodiesel molecule allows for more complete combustion evenin regions of the combustion chamber with fuel-rich diffusion flames, and promotes the oxida-tion of the already formed soot [98]. However, ester molecular structures, such as the methylthat are found in biodiesel, are less effective at reducing soot than other structures. The es-ter group reacts with carbon in the flame through a process called decarboxylation to createCO2. Decarboxylation is important in the combustion process of oxygenated fuels to reduceparticulate matter [99]. Typically fuel-bound oxygen reduces particulate matter formation byforming CO in the fuel-rich portions of the diesel flame, effectively preventing carbon atomsfrom participating in soot precursor reactions [100]. By forming CO2 from fuel-bound oxygeninstead of CO, more oxygen is being used therefore, a smaller amount of carbon is removed


Biodiesel Diesel

n-alkane

iso-alkane

cyclo-alkane

aromatic

Methyl-Oleate (C18:1)

Double BondEster Group

Methyl-Palmitate (C16:0)

Figure 2.11: Chemical diagrams comparing two typical biodiesel molecules with diesel fuelhighlighting differences.

from soot-precursor reactions and the fuel-bound oxygen is not fully utilized [99]. There is astrong correlation between particulate matter emissions and the oxygen content in the fuel.Studies observed that the need for additional oxygen to get a certain reduction in particulatematter emissions was lower when using oxygenated fuel than when using oxygen-enriched airas combustion reagent [101].

Oxygen in the fuel shows a clear trend that reduces the amount of soot in the flame, howeverthe double bond present in the methyl ester has the opposite effect. High-pressure shock tubestudies on the oxidation of Methyl-Octanoate and Methyl-Octenoate showed that there is acorrelation between increased acetylene production and the presence of carbon-carbon doublebonds in the ester structure [14]. In addition, for methyl esters with the same carbon number,studies showed that the presence of a double bond results in significantly higher maximumsoot volume fraction while the exact position of the double bond appears to have only a slightimpact on the amount of soot produced [15]. A study of decene with its double bond at differentpositions showed that a higher yield of benzene, an important soot precursor, was found whenthe double bond was more centrally located. This implied that for fuels with such molecularstructure its pollutant formation characteristics can be significantly different depending on theposition of the double bond in very similar molecules [102].

There is also a difference in the structure of soot particles between biodiesel and dieselfuels with promotes the oxidation of soot from biodiesel. Biodiesel has been found to have amore disordered arrangement of graphene segments in the soot molecules as opposed to dieselsoot. Studies have observed that the internal structure of primary particles had hollow cavitiesprobably caused by the internal oxygen of biodiesel molecules which could also favour faster


oxidation [103]. Studies of different length methyl esters found that shorter alkyl chain lengthsresulted in higher soot reactivity and lower structural order. In addition, the impact of oxygenwithin the fuel on the reactivity of soot became less significant as the carbon chain lengthincreased [104].

Since biodiesel contain virtually no aromatic content, biodiesel blends emit fewer aromaticcompounds than pure diesel [105] There is a close correlation between total PAHs emissionsand particulate matter emissions. Experimental studies comparing diesel with B100 and B20biodiesel can greatly reduce the total PAHs emissions of diesel engine by 19.4% and 13.1%,respectively [106].

2.4 Biodiesel Surrogates

In order to study the more fundamental combustion chemistry process, it is much easier tolook at a simpler fuel or surrogate fuel [107]. A surrogate fuel is a fuel composed of a smallnumber of pure compounds whose behaviour matches certain characteristics of a target fuelthat contains many compounds. Both the chemical and physical characteristics of the targetfuel need to be represented by the surrogate fuel so that the surrogate will properly reproducenot only the combustion characteristics of the fuel, but also the injection, vaporization, andmixing processes that precede ignition in practical devices [97].

In addition to being useful for computational studies, surrogate fuels are important forexperimental work. Because of their simpler compositions, they can provide information andproperty effects on the combustion process to help determine engine efficiency, performance,after-treatment system requirements, and emissions [108]. The compositions of biodiesel anddiesel fuels can vary between batches due to different processing methods and feedstocks. Sur-rogate fuels have the advantage of providing consistent results without any effects of fuel com-position changes.

As mentioned previously, biodiesel is a complex mixture of fatty acid methyl esters whosemolecular structure consists of different degrees of saturation (number of double bonds) andchain lengths. However, the numerous possible reaction pathways for long chain FAME wouldresult in extremely large and complicated chemical kinetic mechanisms which are undesirable[107]. In order to avoid the difficulties associated with long chain FAME, surrogate fuels withshorter chain lengths and known physical chemical properties are chosen for biodiesel com-bustion chemistry studies. Using surrogate fuels simplifies the chemical kinetic mechanism byreducing the number of possible chemical reactions, while still representing the role of the molec-ular structure in combustion such as the role of the methyl ester and the role of carbon-carbondouble bonds. In addition, surrogates fuels are more volatile, and therefore easier to work withexperimentally [107].

Previous studies of a B30 biodiesel surrogate using a a blend of n-Decane, Methyl-Octanoate,and 1-Methylnaphthalene was previously used as a surrogate and showed reasonable agree-


ment between experimental data and computations under various temperature, pressure, andequivalence ratios [109]. Another study of pure biodiesel used a mixture of 50% Methyl-Octanoate/50% n-Decane by mole to represent biodiesel oxidation. The blend was chosen dueto its properties being similar to those of biodiesel: a very close empirical formula, a density of835 kg/m3, and similar autoignition characteristics [110].

This study used the same mixture of 50% Methyl-Octanoate/50% n-Decane by mole torepresent a pure B100 biodiesel. This surrogate was chosen to be similar to previous B30studies but without 1-Methylnaphthalene since there are no aromatics present in biodiesel.Figure 2.12 shows the molecular comparison of the surrogate chosen and similar methyl estersfound in biodiesel.

Methyl-Oleate C19H36O2

Methyl-Stearate C19H38O2

Total C=19 H=40 O=2

n-Decane Methyl-Octanoate

Figure 2.12: Molecular comparison of the methyl-octanoate/n-Decane surrogate and the similarmethyl esters found in biodiesel.

Although the chemical composition is similar to biodiesel, the surrogate does not containa double bond which is also commonly found in biodiesel methyl esters and has been found toaffect the amount of soot produced. In addition, the position of the double bond which alsoaffects soot volume fractions is not accounted for in the surrogate. To determine the effects ofthe double bond and its position, n-Decane was studied on its own and further compared with1-Decene and 5-Decene with their comparison shown in Figure 2.13.


n-Decane Methyl-Octanoate

1-Decene

5-Decene

Figure 2.13: Comparison of n-Decane with 1-Decene and 5-Decene to show the method ofanalysing of the double bond and its position.

Chapter 3

Experimental Methodology

3.1 Burner

A co-annular Gülder burner was used in this study to create a laminar diffusion flame atatmospheric pressure. The burner consists of a 0.43 ′′ inner diameter (ID) stainless steel fueltube with a wall thickness of 0.035 ′′ and a concentric 3.5 ′′ ID air annulus. The combination ofthe fuel transfer line and 14 ′′ long fuel tube allows for proper mixing of the vaporized fuel anddiluent. A schematic of the burner is illustrated in Figure 3.1.

Atomizer +Vaporizer

LiquidMass FlowController

Gas VolumeFlow Meter

Fuel

He PressurizedFuel Tank

Air + O2

Vaporized fuel

BronkhorstVaporizer System

CeramicHoneycomb

Viewingports

CoilHeater

Vertical PositioningStage

N2

HorizontalPositioning

Stages

Air + O2

HeatedTransfer Line

Figure 3.1: Schematic of the burner apparatus with the acrylic tube used for laser extinctionmeasurements.

24

Chapter 3. Experimental Methodology 25

To deliver the vaporized mixture to the burner a heated tube was used with flexible heaters1

at the vaporizer outlet and the burner inlet with the temperature of the heated tube set to 560K.Once the mixture entered the burner it was heated along the fuel tube using coil heaters2 setto 660K to stop the fuel from condensing as it leaves and mixes with the air and allows fora short flame lift-off. Adding extra oxygen with air improves the stability of the flame. Theoxygen and air mixture flows through the air annulus of the burner at 3.30 SLPM and 55 SLPMrespectively. The annulus is filled with 5mm spherical glass beads enclosed by two porous metaldisks which results in a uniform laminar flow velocity profile and improved flame stability. Thisallows for a uniform radial temperature profile at the fuel tube outlet ranging from 580K atthe center-line to 522K located 10mm away from the centre.

The flame is protected from outside air currents using a clear acrylic tube with a 6 ′′ outerdiameter, 1/8 ′′ wall thickness, and 1 ′ long. Different slots are machined into different tubesfor laser extinction and temperature sampling methods to minimize any gaps in which air canenter and prevents any distortion of the flame. On top of the acrylic tube a 100mm tall ceramichoneycomb flow straightener is used to prevent any air recirculation and helps achieve a stableflame. The burner is mounted on two translational stages and connected to a lab jack to allowfor three degrees of freedom. One of the horizontal stages uses a high speed motorized actuator3

to allow for quicker and more accurate movement through the radial direction of the flame.

3.2 Vaporizer

In this experiment the liquid fuel was diluted with nitrogen using a Bronkhorst® Controlled-Evaporator-Mixer (CEM)4 unit consisting of a mass-flow controller for nitrogen (EL-Flow)5,mass-flow meter for the fuel (LIQUI-FLOW)6, and a 3-way mixing valve and evaporator. Theflow rates and vaporizer temperature were controlled using a digital readout system7. Thenitrogen flow rate, fuel flow rate, and temperature were set to 0.900L/min of gas, 16.0 g/h offuel, and 195.0 ◦C respectively. The fuel flow rate is measured using a high precision scale8 (withan accuracy of ±0.1 g) and connected to a computer to closely monitor and calculate the flowrate. The fuel is supplied to the system using a Millipore9 tank pressurized with Helium. Thesolubility of helium in the fuel is assumed to be negligible at the pressures and temperaturesused in the experiment. The pressures used for all liquids and gasses are outlined in Table 3.1.

1Omegalux Catalogue No. SWH171 - 0202O.E.M. Heaters Model No. K4601823Newport Model No. LTA-HS4CEM Model No. W-102A-222-K5EL-Flow Model No. F-201-CV-5K0-AAD-22V6LIQUI-FLOW Model No. L13-AAD-22K-10S7Digital Readout Model No. E-71208Adventure Pro AV8101, OHAUS Corporation, USA9Model No. XX6700P01 | Dispensing Pressure Vessel, 1 gal


Table 3.1: Pressures used for liquids and gasses in the experiment.

Component Pressure (psi)Fuel+Helium 35Air 50Oxygen 35–40Nitrogen 40–45

3.3 Flame Descriptions

Figure 3.2 shows each of the three flames used to measure soot volume fraction and tem-perature. Each of the flames had a height of approximately 7.5–8mm, with n-Decane and theBiodiesel Surrogate being the longest. Both Decene flames were the same height due to thesame flow rate and density.

Figure 3.2: Pictures of all four flames studied.

There is an obvious difference in luminosity between the surrogate, n-Decane, and Deceneflames with the Biodiesel Surrogate having the smallest luminosity area and both Decene flameshaving the largest. Because soot is only formed under fuel rich conditions, it is only producedin the luminous flame regions and will burn out if the fuel-air equivalence ration (ϕ) is less thanone.

3.3.1 Fuel Flow Rate

The flow rate for the biodiesel surrogate was chosen to produce a stable flame with minimalliftoff from the fuel tube. The surrogate was then used as a baseline for determining the rest ofthe flow rates. The flow rate for n-Decane was calculated by matching the same energy density


as the surrogate. Furthermore, both 1-Decene and 5-Decene flow rates were matched by thenumber of carbon atoms as n-Decane. Although B100 was not measured in this experiment thenecessary flow rate was also calculated by matching the energy content of the surrogate. Themolecular weight and heat of combustion of the biodiesel needed to calculate the correct flowrate were found to be 273.1 g/mol and 39.662MJ/kg respectively through laboratory testing.The test results and flow rate calculation can be found in Appendix D. Table 3.2 outlines theflow rates of all fuels used in the experiment.

Table 3.2: Flow rates for each of the fuels tested in the experiment.

Fuel Flow Rate (g/h)Biodiesel Surrogate 18.6n-Decane 16.01-Decene 15.85-Decene 15.8B100 Biodiesel 20.5

3.4 Laser Extinction

Laser Extinction (LE) is a well-established method of measuring the local soot volumefraction throughout the flame. LE is a non-intrusive optical technique that uses the extinctionof light by the soot particle along the optical path. An advantage of using LE over anotheroptical technique to measure soot volume fraction is that measurements can be taken withoutthe need of calibration by another technique [111].

3.4.1 Laser Extinction Theory

When laser light passes through a flame or absorbing medium, light extinction occurs. Theamount of extinction is the sum of both the absorption and scattering of the laser source.The soot particles located within the flame are small enough to be in the Rayleigh regimecharacterized by:

πd/λ <= 0.3 (3.1)

Because of this, scattering of the laser can be neglected [112]. Therefore the transmittanceof the laser through the flame Tλ can be found according to Beer-Lambert’s law giving thefollowing equation:

Tλ = IT /I0 = exp[∫ +∞

−∞Kextdl

](3.2)

Where I0 is the laser beam intensity before it passes through the flame, IT is the attenuatedlaser beam excluding the flame luminosity and Kext is the local extinction coefficient. Assuming


the soot particles are mostly spherical [113], soot volume fraction can be calculated using:

fv =λ

KeKext (3.3)

Ke = 6π(1 + ρs,a)E(m) (3.4)

WhereKe is a dimensionless optical extinction coefficient, ρs,a is the scattering to absorptionratio (zero in this instance) and E is a function of the soot refractive index coefficient m whichcan be found using:

E(m) = − Im(∣∣m2 − 1

∣∣|m2 + 1|

)(3.5)

Combining these we get a soot volume fraction equation of:

fv =Kextλ

6π(1 + ρs,a)E(m)(3.6)

In this experiment, a value of 1.75− 1.03i for 635 nm was used as the refractive index [114].The local extinction coefficient can be calculated using the Three-Point Abel inversion method[115].

3.4.2 Laser Extinction Apparatus

The experimental apparatus used for laser extinction measurements is shown in Figure 3.3.The light source is a 30mW helium-neon laser, and a lock-in amplifier (modulated at 1500Hz)created in LabVIEW was used to isolate the laser signal. The laser power may be reduced usinga neutral density filter however the full power was used to minimize the amount of gain fromthe photodiodes which results in a lower signal to noise ratio. The beam is then polarized andsent through a beam splitter to two photodiodes which measure the laser power (Photodiode1) and the attenuated laser (Photodiode 2). The collection lens is used to refocus the laserbeam that passes through the flame and is located two focal lengths away from the centre ofthe flame. A bandpass filter is used to filter out any wavelengths outside of 632.8±0.2 nm andthe polarizing filters are used to reduce the amount of signal noise.

3.5 Rapid Thermocouple Insertion

Radial temperature profiles were measured at different flame heights using a thermocoupleinsertion apparatus shown in Figure 3.4. A thin uncoated pre-welded R-type thermocouple witha diameter of 75 µm and a junction diameter of 150 µm was used for measurements. In orderto mitigate soot deposits on the junction the thermocouple is rapidly swept into the correctposition in the flame and held there for two seconds. In addition, when exiting the flame the


Photodiode 1P

hotod

iode 2

BandpassFilter

BandpassFilter

Burner

BeamSplitter

CollectionLens

NeutralDensityFilter

DeflectedBeam

2f 2f

HeNe Laser632.8 nm

Viewing port

Chopper Polarizing Beam

Splitter

Lock-In Amplifier

PolarizingFilter

PolarizingFilter

Parallel Polarization

Figure 3.3: Schematic of the laser extinction setup.

junction is brought to a high temperature area to burn off any remaining soot. The maximumvalue of temperature measured was used as the corresponding temperature of that flame region.Catalytic effects of the junction and errors due to conduction along the wires were expected tobe negligible [116]. In addition, correction for radiation loss due to soot deposits was consideredwhen processing the data [117].

Optical Rail

Barrier

NI-9123CeramicTubes

ThermocoupleJunction

Copper Foil

Bracket

PlexiglasPlate

Triggering Signal

To Computer

Burner

Flame

Side ViewTop View

Figure 3.4: Pictures of Rapid Temperature Insertion Setup

Figure 3.5 shows two possible thermocouple readings that occur at different locations withinthe flame. There is an initial response time of the thermocouple to reach its the correct flametemperature. For soot free regions (a) the thermocouple reaches its maximum temperature


and stays constant for the duration of the test. When the thermocouple is inserted into sootcontaining regions (b) a maximum is reached followed by a decrease in the temperature as thesoot deposits onto the thermocouple and radiates heat away from the junction. During thefirst stage the emissivity and diameter of the junction increase both reducing the temperature.The second stage occurs when the junction is completely covered in soot resulting in a constanttemperature loss due to emissivity, but a consistently decreasing temperature due to the furtherincrease in junction diameter.

0

400

800

1200

1600

2000

0 500 1000 1500 2000

Jun

ctio

n T

em

pe

ratu

re (

K)

Time (ms)

(a) Soot free location

(b) Soot containing location

Stage 1 Stage 2

Thermocouple

Response Time

Figure 3.5: Thermocouple measurements for a soot free location (a) and a soot containinglocation (b) within the flame [26].

3.5.1 Correction for Radiation Heat Losses

When a thermocouple is inserted into a flame region containing soot, particles will depositon the junction and increase both its emissivity and diameter. Because of this, soot depositioncan greatly increase the error in a temperature measurement with regards to radiation [118]. Inorder to correct for this, radiation losses from the surface of the thermocouple were calculatedusing the method suggested by Shaddix [119]. In the steady state condition, radiation lossesfrom the thermocouple junction are equal to the heat transferred to the thermocouple from thegas. The heat transfer balance for a thermocouple is calculated by:

Tg = Tm +εσ(Tm

4 − Tw4)d

kNu(3.7)

Where Tg is the gas temperature and Tm is the measured temperature or in this case thethermocouple junction temperature, and Tw is the wall (ambient) temperature to which heat is


radiated (300 K). The other parameters needed are ε the emissivity of the thermocouple junc-tion, σ Stefan-Boltzmann constant (5.67× 10−8 W/m2K2), d the diameter of the thermocouplejunction, Nu the Nusselt number and k the thermal conductivity of the gas.

The thermocouple’s junction diameter, its emissivity and the Nusselt number are three mainfactors that affect radiation losses. A thin 75 µm thermocouple was used to minimize the effectof junction diameter. The value of the emissivity at different temperatures for the uncoatedthermocouple was obtained from [120] and the Nusselt number was estimated to be 2 using thecorrelation suggested by [119]. Due to the rapid insertion of the thermocouple and temperaturemeasurements recorded before significant amounts of soot are deposited, there is a negligibleeffect of soot on the emissivity corrections.

3.6 Apparatus Improvements

Several improvements were made to the apparatus over the course of the experimentaltesting period. These included adding a chopper 10 and lock-in amplifier to isolate the lasersignal, polarization of the laser to improve the analysis and data processing, and an automatedradial positioning stage to increase the accuracy and speed of the experiment.

3.6.1 Lock-In Amplifier

Lock-in Amplifier is an instrument that can detect the amplitude and phase of sinusoidalsignal with known frequency in different signal to noise environments. The basic principle of alock-in amplifier is shown in Figure 3.6 and is mainly composed of three parts: signal channel,reference channel, and the phase sensitive detector (PSD) [121]. The measured signal is firstamplified, then through a filter to remove noise and further amplified before put through thePSD. The reference channel is first sent through a phase shifter to account for any drift in thefrequency and to match the two signals in phase then sent to the PSD as well. Noise is removedby performing a Fourier transform on the input signal at the frequency and phase carried bythe reference signal.

Before the lock-in amplifier was implemented the pure output of the photodiode was usedfor calculating the soot volume fraction. One minute of data was used for each radial flameposition and an average laser intensity was calculated every 0.5 seconds from 1000 samples.Figure 3.7 shows the different in readings when comparing the two methods over 0.5 seconds.It is clear that there is external noise included when only using the photodiode measurements.When the signal is run through the lock-in amplifier the noise is removed and signal slightlyamplified.

In this experiment the two main parameters that were changed to determine optimal settingsof the lock in amplifier were the chopper frequency and the filter time constant. Other exper-iments studying soot in laser light scattering and extinction experiments have used choppers

10Thorlabs Model No. MC2000 with Chopper Blade MC1F15


Signal Channel

Bandpass

FilterAC

Reference Channel

Phase

Shifter

Reference Signal

Measured SignalAC

Phase Sensitive Detector

Lowpass

Filter

Mixer

Output

Figure 3.6: Lock in amplifier schematic showing the three main components.

4.66

4.67

4.68

4.69

4.7

4.71

4.72

4.73

4.74

4.75

0 0.1 0.2 0.3 0.4 0.5

Lase

r In

ten

sity

(V

)

Time (s)

Lock-In Amplifier

Photodiode Only

Figure 3.7: Comparison of lock in amplifier versus only the photodiode when measuring thelaser intensity.

from 1000–2000Hz [122, 123, 124]. An independent study of chopper frequencies measuringboth the laser and flame in Figure 3.8 shows the output of the lock in amplifier at 100Hz,500Hz, 1000Hz, and 1500Hz for one minute of sampling. At very low frequencies (100Hz)a sinusoidal pattern appeared in the signal making it an unsuitable frequency. The outputintensity was consistent over all frequencies with minor differences due to small fluctuations inthe laser source. This shows that the lock in amplifier is able to isolate the laser at a largerange of frequencies. Taking literature into consideration an average frequency of 1500Hz wasused as the chopper frequency for experiments.

The low pass filter time constant was further looked at to determine the optimal lock-inamplifier settings. Literature shows time constants for lock in amplifiers ranging from 0.125–3 seconds [125, 126, 127]. Figure 3.9 shows the laser intensity readings for time constants of0.1 s, 1 s, 5 s, and 10 s in this experimental setup. Setting the time constant to 0.1 s resulted in


4.7

4.71

4.72

4.73

4.74

4.75

4.76

4.77

4.78

4.79

4.8

0 20 40 60 80 100

Lase

r In

ten

sity

(V

)

Sample Number

Chopper Frequency Effects

1500Hz

1000Hz

500Hz

100Hz

Figure 3.8: Difference in laser intensities for different chopper frequencies when measuring thelaser and flame.

having the most detailed but noisy signal while anything past 5 s had a much smoother moreaveraged signal. In this experiment a time constant of 1 s was chosen since it since it had acombination of detail while still having a high signal to noise ratio. This allowed for a betterunderstanding of the soot profiles when taking real-time measurements.

4.73

4.74

4.75

4.76

4.77

4.78

4.79

4.8

0 500 1000 1500 2000 2500 3000

Lase

r In

ten

sity

(V

)

Sample Number

Time Constant Effects

0.1 Sec

1 Sec

5 Sec

10 Sec

Figure 3.9: Difference in laser intensities for different lock-in amplifier time constants whenmeasuring the laser and flame.


3.6.2 Polarization

The LE apparatus was upgraded to include polarizers before splitting the laser as well asbefore entering each photodiode. Figure 3.10 shows the beam path after leaving the HeNelaser and entering the beam splitters. The HeNe laser source is randomly polarized meaningthere is no uniformity of the lasers direction when being split into two beams. Because of this,without any polarization the split beams will have different intensities and trends. This makesit impossible to calculate the soot volume fraction since the ratio of the two signals calculatedusing Equation Equation 3.2 will not be consistent. Using a polarizer reduces the intensity ofthe laser however the combination of lock-in amplifier and gain from the photodiodes gives anacceptable voltage reading.

Photodiode 1

Ph

otodiod

e 2

BandpassFilter

BandpassFilter

BeamSplitter

CollectionLens

DeflectedBeam

Polarizing Beam

Splitter

PolarizingFilter Polarizing

Filter

Parallel Polarization

Figure 3.10: HeNe laser beam path starting at the polarizing beam splitter.

The initial polarizing beam splitter is used to linearly polarize the laser in the horizontaldirection. After the beam passes through the splitter the two different beams are furtherpolarized to improve the extinction ratio of the light and remove any phase shifted light dueto the beam splitter. The effect of polarization is shown in Figure 3.11 and Figure 3.12. Theattenuated laser intensity tends to have more noise than the pure laser due to different amountof gain set on the photodiodes. When there is no polarization, the laser intensity readingsfollow different trends which results in incorrect soot volume fraction results. When the beamsare polarized, the trend of both beams are very consistent with one another allowing for propersoot volume fraction calculations.

3.7 Error Analysis

An experimental uncertainty analysis was conducted for both soot volume fraction andtemperature measurements. This analysis was similar to previous studies using the currentexperimental apparatus [128]. The variance formula was used to calculate the maximum devi-


1.85

1.90

1.95

2.00

4.15

4.20

4.25

4.30

4.35

4.40

4.45

4.50

4.55

0 20 40 60 80 100 120 140 160 180

Att

en

ua

ted

La

ser

Inte

nsi

ty (

V)

Pu

re L

ase

r In

ten

sity

(V

)

Time (s)

Laser Intensity

Attenuated Laser

r = 0.0 mm

r = 0.2 mm

r = 0.4 mm

Without Polarization

Figure 3.11: Trend comparison of attenuated and pure laser intensities without polarization forthree consecutive radial positions at a height of 70mm in the flame.

1.85

1.90

1.95

2.00

4.15

4.20

4.25

4.30

4.35

0 20 40 60 80 100 120 140 160 180

Att

en

ua

ted

La

ser

Inte

nsi

ty (

V)

Pu

re L

ase

r In

ten

sity

(V

)

Time (s)

Laser Intensity

Attenuated Laser

r = 0.0 mm r = 0.2 mm

r = 0.4 mm

With Polarization

Figure 3.12: Trend comparison of attenuated and pure laser intensities with polarization forthree consecutive radial positions at a height of 70mm in the flame.

ation between subsequent soot volume fraction experiments with sample calculations shown inAppendix B:

sf =

√(∂f

∂x

)2

s2x +

(∂f

∂y

)2

s2y +

(∂f

∂z

)2

s2z + ... (3.8)

Here the total error of the function sf is calculated from the combined errors of each


component x, y and z. Knowing the equation for soot volume fraction:

fv =Kextλ

6π(1 + ρs,a)E(m)(3.9)

The total error propagation can be calculated using:

sfv =

√(∂f

∂Kext

)2

s2Kext+

(∂f

∂λ

)2

s2λ +

(∂f

∂ρs,a

)2

s2ρs,a +

(∂f

∂E(m)

)2

s2E(m) (3.10)

The values and errors for each component are outlined in Table 3.3. The uncertainty inthe laser wavelength was considered to be ±2 nm, which is the out of band transmission of thebandpass filters used. Since the scattering of the soot was considered negligible the scatteringto absorption ratio was zero. A variation in refractive index to account for the differences insoot properties as it matures to aid in the accuracy of scattering and extinction diagnostics[129]. An uncertainty of 25% was used for the refractive index. Previous measurements of thedimensionless extinction coefficient estimated the uncertainties to be less than 14% for a bestcase with laser sources, to a maximum of 26% at long wavelengths for other sources whereoptical signal-noise ratios become a factor [130]. Therefore, an error of 20% was chosen for thedimensionless extinction coefficient.

Table 3.3: Values and error for each component of soot volume fraction.

Source Value Errorλ 632.8 nm 2nmρ 0 0E(m) 0.373 25%Kext – 20%

Although the refractive index has the largest percentage of error associated with it the valuesfor Kext are significantly larger, meaning the extinction coefficient is the most significant sourceof error followed by the refractive index with very little error coming from the wavelength. Ifscattering were considered in this experiment, the amount of error would be almost insignificanthowever the calculated soot volume fraction would be changed slightly, but stay within thecalculated error.

Similarly to soot volume fraction, the temperature uncertainty was estimating using theroot-sum-squares analysis method. Table 3.4 outlines the sources of error and their amountwhen measuring temperature.

Catalytic Effects are minimal when taking flame measurements with reported errors smallerthan 30K [116] and coating the thermocouple junction increases the emissivity, diameter, andresponse time [131, 132]. An error of 10K is considered for the effect of conductive heat transferalong the 75 µm thermocouple wire which is obtained by comparing the temperature results ofa 75 µm and a more accurate but fragile 50 µm thermocouple wire [118]. The radiative heat


Table 3.4: Sources of error and their values for thermocouple probe measurements.

Source ErrorCatalytic Effects ±30KConductive Heat Transfer ±10KRadiation Correction ±50KSoot Deposition ±10KPrecision ±5%

transfer between the thermocouple bead and the luminous flame zone is typically not expectedto exceed 50K [117] which was used as the uncertainty value.

The radial position error was determined by analyzing differences in the radial position ofpeak temperature and soot volume fraction during subsequent tests. The largest deviation inradial position was typically 0.2–0.4mm with the larger error occurring at higher flame heightswhere there was the most flicker. Figure 3.13 shows two subsequent tests of soot volume fraction(a) and temperature (b). The temperature profiles were taken at a height of 70mm and hada 0.4mm difference in radial position for peak temperature. The soot volume fraction profileswere taken at a height of 40mm and had a 0.2mm difference in radial position.


4.2 mm,

1,910.8 K

3.8 mm,

1,908.3 K

1500

1700

1900

2100

2 3 4 5 6

Tem

pe

ratu

re (

K)

Radial Position (mm)

Test 1

Test 2(a)

3.80 mm,

2.04 ppm3.60 mm,

1.71 ppm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3 3.5 4 4.5 5

So

ot

Vo

lum

e F

ract

ion

(p

pm

)


Test 1

Test 2(b)

Figure 3.13: Differences in radial position between subsequent tests for maximum temperature(a) and soot volume fraction (b).

Chapter 4

Results and Discussion

4.1 Soot Volume Fraction Profiles

The soot volume fraction profiles of each fuel used in this study are discussed. Each fuel isfirst looked at showing the associated error then compared with one another along with theirradial positions of maximum soot volume fraction. The centre-line measurements have beenshifted by 0.05mm to allow for proper reading of the error. As mentioned earlier, the radialerror for the experiment was ±0.4mm but is not shown for clarity.

4.1.1 Biodiesel Surrogate

Figure 4.1 shows the soot volume fraction profiles of the Biodiesel surrogate used in thisstudy. The surrogate flame was the longest of all studied fuels therefore it was the only flame tohave a profile at 80mm above the fuel tube. In addition, the biodiesel surrogate did not producemeasurable amounts of soot below 50mm. It is seen that maximum soot occurs initially in thewings and quickly moves towards the centre-line. The soot begins to oxidize after it reaches itsmaximum of 1.8±0.4 ppm at 70mm where the soot volume fraction drops significantly.

4.1.2 n-Decane

The soot volume fraction profiles for n-Decane are shown in Figure 4.2. Because of theshorter flame, soot was seen in the flame starting at 40mm. Similarly to the surrogate, thepeak soot volume fractions started near the edge of the fuel tube and moved inwards to thecentre-line with a maximum of 2.3±0.4 ppm occurring at 70mm.

4.1.3 Biodiesel Surrogate vs. n-Decane

Comparing both the surrogate and n-Decane in Figure 4.3, the surrogate produces less sootat all heights below 70mm however these differences are minimal when considering error. Atheights of 70mm and 80mm, the surrogate produces slightly more soot however this is most

39

Chapter 4. Results and Discussion 40

0.0

0.5

1.0

1.5

2.0

2.5

0 1 2 3 4 5

Fv

(p

pm

)


z = 60 mm

0.0

0.5

1.0

1.5

2.0

2.5

0 1 2 3 4 5

Fv

(p

pm

)


z = 50 mm

0.0

0.5

1.0

1.5

2.0

2.5

0 1 2 3 4 5

Fv

(p

pm

)


z = 80 mm

0.0

0.5

1.0

1.5

2.0

2.5

0 1 2 3 4 5

Fv

(p

pm

)


z = 70 mm

Figure 4.1: Soot volume fraction profiles for the biodiesel surrogate.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5

Fv

(p

pm

)


z = 50 mm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5

Fv

(p

pm

)


z = 70 mm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5

Fv

(p

pm

)


z = 40 mm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5

Fv

(p

pm

)


z = 60 mm

Figure 4.2: Soot volume fraction profiles for n-Decane.


likely due to the longer flame. The soot volume fraction measured from n-Decane at 70mm isat approximately 90% of the flame length. The corresponding height for the surrogate fuel at90% is approximately 75mm which gives a similar soot volume fraction profile when comparedwith n-Decane shown in Figure 4.4.

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)Radial Position (mm)

z = 50 mm

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 70 mm

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 40 mm

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 60 mmSurrogate

n-Decane

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 80 mm

Figure 4.3: Soot volume fraction profiles comparing the biodiesel surrogate and n-Decane.

As stated earlier in Chapter 2, the oxygen content within the methyl ester function groupits known to reduce the amount of soot produced in a biodiesel flame. The surrogate usedin this study contained that function group through the methyl-octanoate molecule. This inturn produced a flame with less soot than the straight chained n-Decane molecule. Howeverthe oxygen molecules will only affect two of the carbons located on the methyl ester chainwhich can vary between 12 and 20. The overall soot produced in the surrogate flame was fairly


0

0.5

1

1.5

2

2.5

3

0 1 2 3 4 5

Fv

(p

pm

)


n-Decane

(z = 70mm)

Surrogate

(Estimate for

z = 75mm)

Figure 4.4: Soot volume fraction profiles comparing n-Decane at z = 70mm (90% of total flameheight) and the biodiesel surrogate at the corresponding flame height percentage.

minimal compared to other higher sooting fuels which normally contain aromatics which reachmaximum soot volume fractions of over 8 ppm [26]. This means that while oxygen does reducethe amount of soot formed, the lack of aromatics in biodiesel is the main contributing factor tolower measured soot volume fractions.

4.1.4 Decene Fuels

The effects of the double bond and its position on the soot volume fraction can be seen bycomparing both of the Decene fuels. It was found that for both Decene fuels soot starts earlierin the flame.

4.1.4.1 1-Decene

The soot volume fraction profiles for 1-Decene can be seen in Figure 4.5. With a similarflame height to n-Decane, the soot volume fraction profiles were measured from 40–70mm. Themaximum soot volume fraction follows the same trend with peaks starting at the wings at lowerflame heights, to a maximum of 2.5±0.5 ppm occurring at the 70mm centre-line.


0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5

Fv

(p

pm

)


z = 50 mm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5

Fv

(p

pm

)


z = 70 mm

0

0.5

1

1.5

2

2.5

3

0 1 2 3 4 5

Fv

(p

pm

)


z = 40 mm

0

0.5

1

1.5

2

2.5

3

0 1 2 3 4 5

Fv

(p

pm

)


z = 60 mm

Figure 4.5: Soot volume fraction profiles for 1-Decene.

4.1.4.2 5-Decene

The soot volume fraction profiles for 5-Decene are shown in Figure 4.6. Unlike the otherfuels in this study, 5-Decene produced enough soot at 30mm to be detected in the LE setupallowing for profiles to be measured from 30–70mm. Starting at the wings, the peak sootvolume fraction increased to a maximum of 3.5±0.6 ppm occurring at the 70mm centre-line.

4.1.5 Comparison

Figure 4.7 compares the soot volume fraction of all fuels at every measured flame height. Itis clear that there is a significant increase in soot volume fraction when going from n-Decaneto Decene. With the only difference between n-Decane and either of the Decene fuels is theinclusion of a double bond this has to be the primary source of the increase. In addition, 5-Decene results in a further increase in soot volume fraction when compared to 1-Decene. Whenthe double bond is included in the fuel, an increase in acetylene production results in more sootprecursors. This explains why going from n-Decane to 1-Decene resulted in a higher soot volumefraction. Studies of a more centrally located double bond showed that when the molecule is


0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 1 2 3 4 5

Fv

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pm

)


z = 40 mm

0.0

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1.0

1.5

2.0

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Fv

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)


z = 60 mm

0

0.5

1

1.5

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4.5

0 1 2 3 4 5

Fv

(p

pm

)


z = 30 mm

0

0.5

1

1.5

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3

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4

4.5

0 1 2 3 4 5

Fv

(p

pm

)


z = 50 mm

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 1 2 3 4 5

Fv

(p

pm

)


z = 70 mm

Figure 4.6: Soot volume fraction profiles for 5-Decene.

broken down, the fragments can more easily form into an aromatic species which will resultsin more soot precursors and increase the soot volume fraction [102]. One discrepancy can beseen on the centre-line at 60mm where 1-Decene seems to produce higher soot than 5-Decene.This is likely due to propagation of error during the Abel inversion calculation which typicallyintroduces some error towards the centre-line.

Figure 4.8 shows the peak soot volume fraction at all measured flame positions for each fuel.Here it is seen that the amount of soot produced follows the following trend for all positions in


0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 40 mm

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 60 mm

0

0.5

1

1.5

2

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0 1 2 3 4 5

Fv

(p

pm

)


z = 80 mm

0

0.5

1

1.5

2

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3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 30 mm

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 50 mmSurrogate

n-Decane

1-Decene

5-Decene

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Fv

(p

pm

)


z = 70 mm

Figure 4.7: Maximum soot volume fraction measured at different vertical heights in the flamefor each fuel.

the flame:

Biodiesel Surrogate < n-Decane < 1-Decene < 5-Decene

In addition, the peak soot volume fraction increases until approximately 70mm where it beginsto oxidize and decreases. The measurement of 5-Decene at 60mm decreases from its lowerheight measurement however the trend still follows within error. This further verifies that theinclusion of the oxygen in biodiesel reduces the amount of soot when comparing the BiodieselSurrogate to n-Decane. Also, the double bond increases the amount of soot produced with a


more centrally located double bond producing more soot than a double bond at the end of thecarbon chain.

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0 20 40 60 80 100

Ma

xim

um

So

ot

Vo

lum

e F

ract

ion

(p

pm

)

Vertical Height (mm)

Surrogate

n-Decane

1-Decene

5-Decene


Table 4.1 and Table 4.2 contain the values of the maximum soot volume fractions at eachmeasured flame height and the percentage change from the n-Decane baseline. This shows theeffects of the double bond and its position, and the effects of the methyl ester function group.At lower flame heights there is a significant increase in the amount of measured soot for both1-Decene and 5-Decene. Overall the inclusion of a double bond in the center of the molecule (5-Decene) increases the soot volume fraction more than the surrogate decreases the soot volumefraction when compared to n-Decane. However, pure biodiesel does not contain a double bondin all of its methyl esters nor is the position always centrally located while there is an oxygenon every molecule. This was shown with a larger reduction in soot volume fraction for moresaturated fats that are used for biodiesel.

Table 4.1: Maximum soot volume fraction values for all fuels studied from 40–80mm flameheights.

Fuel z = 40 mm z = 50 mm z = 60 mm z = 70 mm5-Decene 1.88 2.58 2.40 3.461-Decene 0.85 1.79 2.18 2.53Surrogate - 0.38 0.81 1.81n-Decane 0.41 0.66 1.46 2.26


Table 4.2: Percentage difference between the biodiesel surrogate and Decene fuels from n-Decane.

Fuel z = 40 mm z = 50 mm z = 60 mm z = 70 mm5-Decene 359% 291% 64% 53%1-Decene 107% 171% 49% 12%Surrogate - -42% -45% -20%n-Decane - - - -

4.2 Temperature Profiles

In order to determine the effect temperature has on the sooting tendency of each fuel radialtemperature profiles were measured. Each of the four fuels profiles are shown starting at 10mmabove the fuel tube to the top of the flame. The separate profiles for each fuel including its errorcan be found in Appendix A. Since the heat of combustion was used to match the surrogatefuel and n-Decane, and number of carbon atoms were used to match n-Decane with Decene,none of the temperature profiles are significantly different.

4.2.1 Comparison

The temperature profiles for the surrogate, n-Decane, 1-Decene, and 5-Decene are shownin Figure 4.9. All four temperature profiles agree very well for 10mm and 20mm. Startingat 30mm, the surrogate peak temperature stays further away from the centre-line due to thelonger flame length. This is also seen at higher flame heights for n-Decane which had a flamelength in between the surrogate and Decene fuels.

The sudden jumps in temperature seen around 3.5–4mm for heights at 30–60mm in theflame are due to its temperature being above 1500K when oxidation of the soot begins. Attemperatures below 1500K soot deposits on the thermocouple junction which reduces the overalltemperature measured. Once the thermocouple is inserted into radial positions that are able toburn the fuel off of the junction, the temperature spike occurs. The similarity of all temperatureprofiles means the soot particles follow the same evolution process in each flame, therefore thereis minimal temperature effects on the soot volume fraction and may be neglected.

4.2.2 Center Line and Maximum Temperatures

The centre-line temperatures for each flame are shown in Figure 4.10 and vary from 700Kat the lowest height in the flame to 1900K at the highest point. The differences in temperaturesbetween the fuels are due to slightly different conditions between tests and are all within error.

In addition to centre-line temperatures, the peak temperatures for each vertical positionare shown in Figure 4.11. The maximum temperatures are located at the radius of the fuelnozzle at lower flame heights, and move towards the centre-line when moving up the flame.


500

700

900

1100

1300

1500

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2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 80 mm

500

700

900

1100

1300

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2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 70 mm

500

700

900

1100

1300

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1700

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2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 60 mm

500

700

900

1100

1300

1500

1700

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2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 50 mm

500

700

900

1100

1300

1500

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1900

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2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)

Title

z = 40 mm

500

700

900

1100

1300

1500

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1900

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2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)

Title

z = 30 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 20 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 10 mmSurrogate

n-Decane

1-Decene

5-Decene


The peak temperatures increase until approximately 40–50mm above the fuel tube and thendecrease significantly. Again, because of the longer surrogate and n-Decane flame heights the


0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 20 40 60 80

Ce

nte

rlin

e T

em

pe

ratu

re (

K)

Flame Height (mm)

Surrogate

n-Decane

1-Decene

5-Decene


peak temperatures occur at higher positions in the flame. Both Decene flames have higher sootconcentrations than the surrogate and n-Decane which results in lower flame temperatures byapproximately 50–100K. This is because soot particles radiate strongly which decreases localflame temperatures. In addition, the shorter Decene flames means the temperature peaks atlower heights in the flame. Since soot formation tends to increase with temperature, the higherDecene soot concentrations are not due to any temperature effects.


1600

1650

1700

1750

1800

1850

1900

1950

2000

2050

2100

0 20 40 60 80

Ma

xim

um

Te

mp

era

ture

(K

)

Flame Height (mm)

Surrogate

n-Decane

1-Decene

5-Decene


Chapter 5

Conclusions and Recommendations

5.1 Conclusions

An experimental study of soot volume fractions and temperatures in a co-flow laminardiffusion flame using laser extinction and rapid thermocouple insertion were done on a biodieselsurrogate, n-Decane, 1-Decene, and 5-Decene. The biodiesel surrogate was composted of amixture of 50% n-Decane and 50% methyl-octanoate by mole to represent an average fatty acidmethyl ester found in pure B100 biodiesel.

In order to study the effects of the ester function group contained in biodiesel molecules,n-Decane was used. Although the chemical composition of the surrogate is similar to biodieselit does not contain a double bond which has been shown to affect the soot volume fraction. Todetermine the effects of the double bond and its position, both 1-Decene which contains thedouble bond at the end of the molecule, and 5-Decene which contains the double bond in themiddle were studied.

Generally, all of the fuels have very similar temperature profiles at different flame heights.This is because the heat of combustion was used to match the flow rates of the biodieselsurrogate and n-Decane, while the number of carbons was used to match n-Decane with bothDecene fuels. However the Decene flames with higher soot concentrations and shorter flamelengths have lower flame temperatures due to the strong radiation of the soot particles whichin turn decreases the local flame temperature.

Because of the similar flame temperatures, difference in soot volume fraction measurementsmust only come from difference in fuel composition which in this case are the ester functiongroup and the double bond.

The sooting tendency of the biodiesel surrogate was lower than all of the other fuels studiedand significantly lower than both Decene fuels. When comparing the surrogate to n-Decanethis means the inclusion of the ester group moderately reduces the amount of soot produced.

Looking at the inclusion of a double bond both 1-Decene and 5-Decene produced more sootthan n-Decane, with 5-Decene producing the most soot at all measured heights in the flame.This means that the inclusion of a double bond increases the amount of soot and a more central

51

Chapter 5. Conclusions and Recommendations 52

position in the molecule further increases the soot volume fraction.

5.2 Recommendations

The following outlines improvements can be made to both the apparatus and processingmethods as well as other experiments than can provide a more comprehensive understandingof biodiesel fuel.

5.2.1 Improvements to Methodology

There are four main improvements to the experimental setup and methodology that can beundertaken to improve both soot volume fraction and temperature results. They are as follows:

1. The current laser used in the extinction apparatus is unable to detect transparent sootprecursor particles. This results in a lower soot volume fraction at the current detectablepositions as well as the inability to detect soot at low flame heights. Using a UV laserwill allow for detection of the transparent particles as well as PAHs can be combined withthe current HeNe laser apparatus.

2. In addition to adding a laser to detect transparent particles, the index of refraction be-tween different stages of soot will not be consistent. The index of refraction of bothprecursor and mature particles can be measured using a multiple angle laser scatteringdetection apparatus. These results can be used during processing of the laser extinctiondata to provide a more comprehensive profile of the flames refractive index.

3. Currently the carrier gas for the liquid fuels is Nitrogen. Diluting the fuel creates a loweroverall flame temperature which can affect the soot volume fraction results. Althoughthe difference from ambient flame temperature is not significant, replacing the carriergas to another inert gas such as Argon will bring the temperature closer to the desiredconditions.

4. Flame stability and flicker is another issue that can be improved upon by reducing thelength of the heated fuel tube the evaporated fuel travels through before it reaches theburner. A longer line increases the chance of vertical flame flicker which is undesirablewhen testing.

5. The current experimental apparatus was unable to keep the vaporized B100 biodieselfuel temperature above its condensation point. In order to create a biodiesel flame thevaporizer and heated transfer line should be able to reach temperatures greater than300 ◦C. In addition, shortening of the transfer line will reduce the amount of time thevaporized fuel has to cool down and condense, and results in a more stable flame.

Chapter 5. Conclusions and Recommendations 53

5.2.2 Future Tests/Comparisons

There are several tests that can be done to further enhance the results that were gathered.

1. Because biodiesel was unable to be run through the apparatus it would be advantageousto measure the soot volume fraction of a B100 biodiesel. Either a vegetable oil or animalfat based feedstock could be used with minimal differences in soot volume fraction dueto saturation however biodiesel made from vegetable oil is more common throughout theworld.

2. One disadvantage of measuring a specific biodiesel is the variation in feed-stocks andprocessing techniques used. This can be further expanded upon by measuring commonmethyl esters in biodiesel such as Stearic acid (C18:0) which does not contain a doublebond and Oleic acid (C18:1) which does contain a double bond.

3. Analyzing the soot throughout the flame using either a transmission electron microscope(TEM) or high resolution TEM would also be beneficial. These results can be used tocalculate the soot volume fraction as a comparison to the laser extinction measurements,as well as analyze the soot particles further than what laser extinction is capable of byproviding particle diameters (dp), and number of particles (np).

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Appendix A

Temperature Profiles

A.1 Inlet Profiles

400

600

800

1000

1200

1400

1600

1800

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


Surrogate

n-Decane

1-Decene

5-Decene

Figure A.1: Temperature profiles for all fuels at the fuel tube inlet.

65

Appendix A. Temperature Profiles 66

A.2 Surrogate

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 80 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 70 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 60 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 50 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 40 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 30 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 20 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 10 mm

Figure A.2: Temperature profiles with error for biodiesel surrogate.


A.3 n-Decane

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 70 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 60 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 50 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 40 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 30 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 20 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 10 mm

Figure A.3: Temperature profiles with error for n-Decane.


A.4 1-Decene

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 70 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 60 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 50 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 40 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 30 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 20 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 10 mm

Figure A.4: Temperature profiles with error for 1-Decene.


A.5 5-Decene

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 70 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 60 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 50 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 40 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 30 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 20 mm

500

700

900

1100

1300

1500

1700

1900

2100

2300

0 2 4 6 8 10

Tem

pe

ratu

re (

K)


z = 10 mm

Figure A.5: Temperature profiles with error for 5-Decene.

Appendix B

Error Analysis

B.1 Soot Volume Fraction Error

This sample error calculation is for the biodiesel surrogate at a height z = 60mm in the flameand radial position r = 1.4mm. This gives values for local extinction coefficient of Kext = 7.24,wavelength λ = 632.8 nm, scattering to absorption ratio ρs,a = 0, and E(m) = 0.373.

Using Table 3.3 the error associated with each component is used in the variance equationas follows:

sfv =

(λ

6π(1 + ρs,a)E(m)sKext

)2

+

(Kext

6π(1 + ρs,a)E(m)sλ

)2

+

(− λKext

6π(1 + ρs,a)E(m)2sE(m)

)2

(B.1)With a local extinction coefficient error of 1.45, wavelength error of 2 nm, and refractive

index error of 0.09325 this gives us:

sfv =

√(0.1305)2 + (7.63E−4)2 + (−2.25E−2)2 (B.2a)

sfv = 1.32E−1 (B.2b)

70

Appendix C

MATLAB Code

C.1 Soot Volume Fraction MATLAB Code

1 c l o s e a l l ;2 c l c ;3 c l e a r ;4

5 V1=csvread ( ’V1 . csv ’ ) ;6 V2=csvread ( ’V2 . csv ’ ) ;7 I = Vcalc (V1) ;8 I0 = Vcalc (V2) ;9

10 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%11

12 I 0 c o r r e c t ed = I (1 ) . * I0 ( 1 : end ) . / I0 (1 ) ;13 s t a r t p o i n t = 2 ;14 I = I ( s t a r t p o i n t : end ) ;15 I 0 c o r r e c t ed = I0 co r r e c t ed ( s t a r t p o i n t : end ) ;16

17 r a t i o = I . / I 0 c o r r e c t ed ;18 f o r i = 1 : l ength ( r a t i o )19 i f r a t i o ( i ) > 120 r a t i o ( i ) = 1 ;21 end22 end23

24 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%25

71

Appendix C. MATLAB Code 72

26 [ F ,D, I ,X, Fv]=main ( ra t i o ’ , 0 . 2 ) ;27

28 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%29

30 x = 0 : 0 . 2 : ( s i z e (Fv , 1 )−1) * 0 . 2 ;31

32 f i g u r e ;33 hold a l l ;34 p lo t (x , Fv*10^6 , ’ ’ , ’ LineWidth ’ , 4 )35 Fv = smooth (Fv , 9 , ’ l o e s s ’ ) ;36 f o r j = 1 : l ength (Fv) ;37 i f Fv( j ) < 0 ;38 Fv( j ) = 0 ;39 end40 end41 p lo t (x , Fv*10^6 , ’ ’ , ’ LineWidth ’ , 4 )42 ax i s ( [ 0 5 0 5 ] ) ;43 Soot = Fv*10^6;44

45 x l sw r i t e ( ’ Soot . x l s ’ , Soot )46

47 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

1 f unc t i on [ I ] = Vcalc (V)2 f o r i =1: l ength (V)3 %looks f o r when ambient l i g h t i s read (2x drop in vo l tage )4 i f ( ( (max(V)−V( i ) ) /V( i ) )>2)5 drop=i ;6 break ;7 end8 end9 V1=V(1 : drop−1) ;

10

11 Lum=V( length (V1)+1:end ) ;12

13 f o r i =1: s i z e (V1 , 1 )14 i f (mod( i , 1 20 )==0)15 I ( i /120)=sum(V1( i −119: i ) ) /120 ;16 end17 end


18 end19

20 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

1 f unc t i on [F ,D, I ,X, Fv]=main ( I I0 , l )2

3 i_ i0=−l og ( I I 0 ) ;4 x=0: l : l *(max( s i z e ( i_i0 ) )−1) ;5

6 [ F ,D, Fv]= Inve r s i on ( i_i0 , x , l ) ;7 I=i_i0 ;8 X=x ;9 end

10

11 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%12

13 f unc t i on [F ,D, Fv]= Inve r s i on ( I_I0 , x , l )14 i =0:max( s i z e ( x ) ) ;15 j =0:max( s i z e ( x ) ) ;16 I=i +1;17 J=j +1;18

19 f o r i =0:max( s i z e ( x ) )−120 f o r j =0:max( s i z e ( x ) )−121 i f ( j <( i −1) )22 D( i +1, j +1)=0;23 e l s e i f ( ( i −1)==j )24 D( i +1, j +1)=I0 ( i , j +1)−I1 ( i , j +1) ;25 e l s e i f ( i==j )26 D( i +1, j +1)=I0 ( i , j +1)−I1 ( i , j +1)+2*I1 ( i , j ) ;27 e l s e i f ( ( i +1)<=j )28 D( i +1, j +1)=I0 ( i , j +1)−I1 ( i , j +1)+2*I1 ( i , j )−I0 (

i , j−1)−I1 ( i , j−1) ;29 i f ( i==0 & j==1)30 D( i +1, j +1)=I0 ( i , j +1)−I1 ( i , j +1)+2*I1 ( i , j )

−2*I1 ( i , j−1) ;31 end32 end33 end34 end


35 end36 end37 end38 F=(1/( l * . 001 ) ) *(D*I_I0 ) ;39 m=1.75−1.03 i ;40 Fv=632.8e−9*F/(6* p i *(− imag ( (m^2−1) /(m^2+2) ) ) ) ;41 end42

43 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%44

45 f unc t i on I z e r o=I0 ( i , j )46 i f ( ( i==0 & j==0) | ( j<i ) )47 I z e r o =0;48 end49 i f ( ( i==j ) & ( j ~=0) )50 I z e r o =(1/(2* p i ) ) * l og ( ( sq r t ( (2* j +1)^2−4* i ^2)+2* j +1)/(2* j ) ) ;51 end52 i f ( i<j )53 I z e r o =(1/(2* p i ) ) * l og ( ( sq r t ( (2* j +1)^2−4* i ^2)+2* j +1)/( sq r t ( (2* j−1)

^2−4* i ^2)+2*j−1) ) ;54 end55 end56

57 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%58

59 f unc t i on Ione=I1 ( i , j )60 i f ( j<i )61 Ione=0;62 e l s e i f ( i==j )63 Ione =(1/(2* p i ) ) * sq r t ( (2* j +1)^2−(2* i ) ^2)−2* j * I0 ( i , j ) ;64 e l s e65 Ione =(1/(2* p i ) ) *( sq r t ( (2* j +1)^2−(2* i ) ^2)−s q r t ( (2* j−1)^2−(2* i

) ^2) )−2* j * I0 ( i , j ) ;66 end67 end68 end

C.2 Temperature MATLAB Code

1 c l e a r ;


2

3 f i l e = u i g e t f i l e ( ’ . csv ’ ) ;4 T = csvread ( f i l e ) ;5

6 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%7

8 Te=[9009 1000

10 110011 120012 130013 140014 145015 ] ;16

17 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%18

19 emis =[0.172320 0 .183721 0 .193722 0 .203223 0 .212224 0 .220625 0 .224326 ] ;27

28 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%29

30 Tk=[80031 90032 100033 ] ;34

35 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%36

37 k=[57.2538 62 .5439 67 .6840 ] ;


41

42 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%43

44 E=po l y f i t (Te , emis , 1 ) ;% f i t s a l i n e a r curve to emis data45 K=po l y f i t (Tk , k , 1 ) ;% f i t s a l i n e a r curve to k data46

47 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%48

49 j =0;50 f o r i =1: s i z e (T, 1 )51 i f (mod( ( i −1) ,200)==0)52 j=j +1;53 Tmax( j )=max(T( i : i +199) )+273;% change i f number o f data per

po int i s more than 200 (2 sec )54 Tj ( j )=sum(T( i +25: i +49) ) /25+273;% change i f you want to

average over another time i n t e r v a l55 Tg1( j )=Tj ( j )+po lyva l (E, Tj ( j ) ) *0 .0000000567*0 .000075*( Tj ( j )

^4−296^4) /( .001*2* po lyva l (K, Tj ( j ) ) )56 Tg( j )=Tj ( j )+po lyva l (E, Tj ( j ) ) *0 .0000000567*0 .000075*( Tj ( j )

^4−296^4) /( .001*2* po lyva l (K, Tg1( j ) ) )57 end58 end59

60 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%61

62 f o r j =1: s i z e (Tg , 2 )−2% I s t a r t ed g e t t i n g data from 0 .4 mm (2i n t e r v a l s ) be f o r e cente r l i n e . change i t i f use another method

63 Tmax( j )=Tmax( j +2) ;64 Tg( j )=Tg( j +2) ;65 end66

67 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%68

69 x=0 : . 2 : . 2 * ( s i z e (Tg , 2 )−1) ;70

71 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%72

73 hold a l l74 p lo t (x ,Tg , ’ LineWidth ’ , 2 )


75 ax i s ( [ 0 15 0 3000 ] )76 x l ab e l ( ’R (mm) ’ )77 y l ab e l ( ’T (K) ’ )78 Temperature = Tg ;79

80 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%81

82 x l sw r i t e ( [ f i l e ’ . x l s ’ ] , Temperature ’ )83

84 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Appendix D

Biodiesel

Since B100 biodiesel was unable to be run through the experimental apparatus the follow-ing is the necessary information needed to use pure biodiesel under the same conditions as acomparison to the other fuels. The obtained biodiesel was produced from animal fats with asample sent for testing of several important parameters outlined below.

D.1 Biodiesel Test Results

The biodiesel was tested for its heat of combustion and gas chromatography needed tocalculate its flow rate. In addition its acid number was tested to determine how much it hadaged since it was first obtained. Finally its iodine number was tested for an indication of howsaturated the used feedstock was.

Table D.1: Test results of several parameters for B100 biodiesel produced from animal fats.

Test Parameter ResultASTM D4809 Gross Heat of Combustion 39.662 MJ/kg

Net Heat of Combustion 37.064 MJ/kg

ASTM 664 Acid Number 0.28 mgKOH/g

EN 14103 Ester Content 100m/m) %(m/m)Linolenic Acid Methyl Ester Content 0.88 %(m/m)

EN 14111 Iodine Value 59

The biodiesel molecular weight was calculated using the FAME composition test resultsoutlined in Table D.2. Only FAME with a mass % higher than 0.2 was used in the calculation.In addition any unknown fame used the molecular weight of the previous know FAME. Thesetwo conditions accounted for 98% of the total FAME which was further adjusted to 100% givinga total molecular weight of 273.01 g/mol

78

Appendix D. Biodiesel 79

Table D.2: Free acid methyl ester (FAME) composition analysis by gas chromatography.

Peak # Fame ID Mass % FilteredMass %

MW(g/mol)

AverageMW

1 c8:0 02 c9:0 03 c10:0 0.064 c11:0 05 c11:1 06 c12:0 0.0857 c12:1 0.0098 c13:0 0.0119 c13:1 0.03210 C14:0 2.175 2.175 228.3709 4.9711 c14:1 0.454 0.454 226.355 1.0312 unknown FAME 0.1313 c15:0 0.295 0.295 242.3975 0.7214 Polyunsaturated FAME 0.02115 Polyunsaturated FAME 0.00516 c15:1 0.13217 c16:0 22.781 22.781 256.4241 58.4218 c16:1 3.17 3.17 254.4082 8.0619 unknown FAME 0.29 0.29 254.4082 0.7420 unknown FAME 0.421 0.421 254.4082 1.0721 unknown FAME 0.01222 c17:0 0.738 0.738 270.4507 2.0023 c17:1 0.48 0.48 268.4348 1.2924 Polyunsaturated FAME 0.09625 Polyunsaturated FAME 0.00826 Polyunsaturated FAME 0.01827 c18:0 14.035 14.035 284.4772 39.9328 c18:1 42.072 42.072 282.4614 118.8429 unknown FAME 0.309 0.309 282.4614 0.8730 unknown FAME 0.05331 unknown FAME 0.271 0.27132 c18:2 8.619 8.619 280.4455 24.1733 unknown FAME 0.229 0.229 280.4455 0.6434 c19:0 0.05635 unknown FAME 0.03836 unknown FAME 0.08637 unknown FAME 0.06538 c18:3 0.0339 c18:3 0.845 0.845 278.4296 2.3540 Polyunsaturated FAME 0.024

Continued on next page


Table D.2 – continued from previous page

Peak # Fame ID Mass % FilteredMass %

MW(g/mol)

AverageMW

41 Polyunsaturated FAME 0.266 0.266 278.4296 0.7442 Polyunsaturated FAME 0.01743 Polyunsaturated FAME 0.00744 c20:0 0.17545 unknown FAME 0.00446 c20:1 0.578 0.578 310.5145 1.7947 unknown FAME 0.02448 unknown FAME 0.02149 unknown FAME 0.01250 unknown FAME 0.00451 c20:2 0.19552 unknown FAME 0.01353 c20:3 0.01754 c21:0 0.07255 Polyunsaturated FAME 0.00356 c20:4 0.12357 c20:5 0.03558 Polyunsaturated FAME 0.00659 c22:0 0.03760 unknown FAME 0.03261 c22:1 0.0262 c22:2 0.02663 c22:3 0.02364 c23:0 0.03965 c22:4 066 c22:5 067 c24:0 0.03868 c24:1 0.0669 c22:6 0

Total 100.00 98.028 4533.32 267.62Adjusted 273.01


D.2 Biodiesel Flow Rate

The necessary flow rate for biodiesel in this experiment was calculated to match the heatof combustion of the stable surrogate flame. First the average molecular weight and heat ofcombustion were calculated for the 50-50 mole percent blend of methyl-octanoate and n-Decanegiving:n-Decane:

∆Hc,C10H22 = 6778.33 kJ/mol, (D.1a)

MWC10H22 = 142.2817 g/mol (D.1b)

Methyl-Octanote:

∆Hc,C9H18O2 = 5493.6 kJ/mol, (D.2a)

MWC9H18O2 = 158.238 g/mol (D.2b)

Surrogate:

∆Hc,surrogate = 6135.665 kJ/mol, (D.3a)

MWsurrogate = 150.26 g/mol (D.3b)

Therefore the surrogate energy to match for a flow rate of 18.6 g/h is:

Energy = ∆Hc × m/MW, (D.4a)

Energy = 759.51 kJ/h (D.4b)

Using the biodiesel heat of combustion ∆Hc,net = 37.064 kJ/g and the calculated molecularweight of 273.01 g/mol the biodiesel flow rate is calculated to be:

m×∆Hc (Biodiesel) = 759.51 kJ/h (Surrogate) (D.5a)

m× 37.064 = 759.51 kJ/h (D.5b)

m = 20.49 g/h (D.5c)

Appendix E

Flow Rates

Flow rates were measured during each experiment using a scale with an accuracy of ±0.1 g.A deviation of ±0.3 g/h was allowed for different days of testing. The fuel was flowed throughthe system for at least one hour before any tests were started to allow for a more stable flame.In addition, the readings were watched throughout the experiment to determine if the flow ratesettled down to the correct value and remained constant.

E.1 Surrogate

17

17.5

18

18.5

19

19.5

20

0 3000 6000 9000 12000 15000

Flo

w R

ate

(g

/h)

Time (s)

Figure E.1: Scale reading of the biodiesel surrogate for a target flow rate of 18.6 g/h.

82

Appendix E. Flow Rates 83

E.2 n-Decane

14.5

15

15.5

16

16.5

17

17.5

0 3000 6000 9000 12000 15000

Flo

w R

ate

(g

/h)

Time (s)

Figure E.2: Scale reading of n-Decane for a target flow rate of 16.0 g/h.

E.3 Decene

13.5

14

14.5

15

15.5

16

16.5

0 3000 6000 9000 12000

Flo

w R

ate

(g

/h)

Time (s)

Figure E.3: Scale reading of Decene for a target flow rate of 15.8 g/h.

Appendix F

Raw Data

F.1 Soot Volume Fraction

Table F.1: Soot volume fraction data for the biodiesel surrogate fuel.

Biodiesel Surrogatex position z = 50 z = 60 z = 70 z = 80

0 0 0.40 1.81 0.450.2 0 0.52 1.71 0.280.4 0 0.52 1.38 0.240.6 0 0.51 1.13 0.130.8 0 0.56 1.08 01 0 0.56 0.90 0

1.2 0 0.64 0.79 01.4 0 0.65 0.63 01.6 0 0.77 0.54 01.8 0 0.81 0.35 02 0 0.80 0.14 0

2.2 0 0.80 0.09 02.4 0.12 0.72 0.03 02.6 0.20 0.69 0 02.8 0.32 0.58 0 03 0.38 0.51 0 0

3.2 0.38 0.39 0 03.4 0.20 0.29 0 03.6 0.13 0.18 0 03.8 0.06 0.06 0 04 0 0 0 0

4.2 0 0 0 04.4 0 0 0 04.6 0 0 0 04.8 0 0 0 05 0 0 0 0

84

Appendix F. Raw Data 85

Table F.2: Soot volume fraction data for the n-Decane fuel.

n-Decanex position z = 40 z = 50 z = 60 z = 70

0 0 0 0.68 2.260.2 0 0 0.68 1.170.4 0 0.01 0.69 0.820.6 0 0.02 0.75 0.490.8 0 0.01 0.82 0.561 0 0.02 0.78 0.40

1.2 0 0.02 0.83 0.161.4 0 0.02 0.96 0.231.6 0 0.08 1.07 0.131.8 0 0.07 1.24 0.102 0 0.08 1.38 0.05

2.2 0 0.12 1.46 02.4 0 0.12 1.44 02.6 0 0.20 1.32 02.8 0.04 0.36 1.12 03 0.09 0.51 0.95 0

3.2 0.18 0.66 0.68 03.4 0.24 0.66 0.41 03.6 0.35 0.54 0.20 03.8 0.40 0.41 0.12 04 0.41 0.24 0.03 0

4.2 0.36 0.11 0 04.4 0.33 0.02 0 04.6 0.19 0.01 0 04.8 0.08 0 0 05 0 0 0 0


Table F.3: Soot volume fraction data for the 1-Decene fuel.

1-Decenex position z = 40 z = 50 z = 60 z = 70

0 0 0 2.16 2.530.2 0 0 2.18 2.480.4 0 0 2.13 2.380.6 0 0 2.08 2.260.8 0 0 2.02 2.09

1 0 0 2.00 1.881.2 0 0 2.01 1.631.4 0 0.0 2.02 1.371.6 0 0.1 2.04 1.061.8 0 0.3 2.02 0.73

2 0 0.6 1.90 0.412.2 0 0.9 1.74 0.112.4 0.00 1.3 1.47 02.6 0.10 1.6 1.14 02.8 0.18 1.8 0.79 0

3 0.27 1.8 0.49 03.2 0.41 1.6 0.23 03.4 0.61 1.3 0.08 03.6 0.78 1.0 0.01 03.8 0.85 0.8 0 0

4 0.71 0.5 0 04.2 0.45 0.4 0 04.4 0.27 0.2 0 04.6 0.23 0.1 0 04.8 0.10 0.1 0 0

5 0 0 0 0


Table F.4: Soot volume fraction data for the 5-Decene fuel.

5-Decenex position z = 30 z = 40 z = 50 z = 60 z = 70

0 0 0 0.75 1.72 3.460.2 0 0 0.77 1.68 3.440.4 0 0.01 0.77 1.70 3.290.6 0 0.04 0.76 1.77 2.980.8 0 0.04 0.75 1.90 2.541 0 0.07 0.72 2.09 2.01

1.2 0 0.13 0.66 2.26 1.351.4 0 0.15 0.65 2.36 0.731.6 0 0.17 0.71 2.40 0.321.8 0 0.21 0.84 2.39 0.082 0 0.24 1.04 2.35 0

2.2 0 0.27 1.26 2.28 02.4 0 0.26 1.49 2.12 02.6 0.02 0.24 1.74 1.96 02.8 0.03 0.27 2.02 1.83 03 0.04 0.40 2.35 1.64 0

3.2 0.09 0.70 2.58 1.28 03.4 0.20 1.16 2.54 0.84 03.6 0.36 1.63 2.18 0.53 03.8 0.57 1.88 1.53 0.39 04 0.77 1.73 0.82 0.28 0

4.2 0.78 1.22 0.28 0.19 04.4 0.61 0.68 0.07 0.14 04.6 0.42 0.31 0 0.10 04.8 0.20 0.04 0 0.06 05 0.07 0 0 0.03 0


F.2 Temperature

Table F.5: Temperature data for the biodiesel surrogate fuel.

Biodiesel Surrogatex z = 10 z = 20 z = 30 z = 40 z = 50 z = 60 z = 70 z = 800 701.4 820.8 1033.3 1228.6 1509.4 1587.0 1842.0 1903.70.2 708.4 826.4 1030.6 1221.4 1492.4 1573.3 1861.6 1918.00.4 702.0 836.6 1033.8 1216.3 1507.7 1567.6 1836.2 1918.50.6 704.2 850.4 1040.3 1217.9 1501.4 1559.7 1838.8 1922.40.8 709.2 868.5 1050.9 1218.1 1511.9 1553.7 1846.9 1919.71 714.4 890.8 1063.6 1234.8 1518.5 1557.7 1852.7 1921.71.2 725.7 919.8 1077.0 1249.2 1527.7 1558.8 1847.2 1922.31.4 737.2 941.5 1102.6 1251.0 1529.1 1553.9 1840.8 1920.51.6 753.4 981.4 1127.5 1281.1 1559.1 1562.4 1863.9 1919.71.8 773.9 1014.3 1145.1 1309.1 1548.5 1576.3 1871.8 1918.22 799.0 1055.3 1184.1 1314.8 1586.4 1579.1 1879.5 1911.62.2 826.9 1099.8 1203.7 1337.6 1593.7 1577.4 1887.2 1896.52.4 867.0 1125.9 1234.7 1359.5 1606.4 1587.2 1901.2 1901.22.6 910.7 1173.7 1269.0 1427.8 1623.6 1605.2 1912.5 1879.62.8 963.6 1228.1 1312.3 1468.5 1626.8 1635.7 1929.3 1887.63 1006.3 1265.7 1344.4 1478.9 1650.1 1706.6 1921.9 1872.53.2 1066.4 1317.3 1395.5 1507.3 1688.0 1691.2 1951.5 1860.13.4 1119.5 1372.0 1420.1 1555.1 1749.2 1801.3 1947.8 1852.63.6 1180.9 1411.0 1451.2 1591.9 1800.2 1920.8 1950.1 1836.23.8 1244.5 1453.8 1489.1 1658.1 1827.2 1913.3 1941.3 1823.44 1313.6 1490.7 1532.6 1657.0 1931.3 1964.9 1931.9 1822.84.2 1379.2 1532.3 1516.3 1696.8 1992.2 1988.3 1894.4 1799.64.4 1453.3 1576.9 1526.6 1749.5 1998.7 2001.0 1888.7 1787.34.6 1510.2 1628.5 1580.3 1818.2 2036.2 2017.6 1890.2 1791.24.8 1553.9 1686.0 1652.3 1801.6 2027.1 2019.0 1867.0 1742.95 1594.8 1805.0 1819.0 1883.5 2011.3 2015.6 1853.1 1739.65.2 1655.2 1929.4 1952.0 1974.6 2004.4 1981.8 1790.3 1720.55.4 1788.2 1963.9 1982.7 1987.9 1912.6 1959.6 1781.0 1705.55.6 1886.0 1965.3 1987.7 2002.7 1931.7 1930.5 1775.2 1683.55.8 1918.1 1923.4 1963.4 1982.6 1866.2 1901.4 1752.3 1659.36 1898.5 1883.0 1901.7 1930.0 1817.1 1861.1 1731.5 1634.86.2 1842.5 1824.5 1861.2 1901.7 1736.5 1855.6 1658.4 1626.06.4 1768.9 1773.4 1820.7 1877.8 1755.2 1785.9 1670.7 1562.96.6 1707.5 1723.6 1774.6 1832.2 1669.6 1761.8 1631.0 1561.36.8 1639.0 1645.6 1716.7 1763.0 1632.0 1739.1 1580.6 1550.37 1554.2 1569.1 1661.3 1715.9 1554.0 1690.1 1597.4 1492.67.2 1478.2 1533.2 1605.5 1671.3 1534.7 1673.1 1515.5 1506.07.4 1411.9 1455.1 1549.0 1625.2 1495.6 1615.8 1508.8 1461.87.6 1333.7 1406.3 1515.9 1565.3 1451.2 1601.2 1452.3 1439.67.8 1248.5 1345.7 1468.8 1518.5 1354.1 1523.2 1438.5 1412.68 1183.1 1265.6 1415.6 1472.7 1387.1 1514.7 1385.8 1344.58.2 1097.3 1204.4 1348.9 1396.4 1315.6 1452.9 1384.4 1342.48.4 1026.9 1147.4 1306.6 1327.5 1225.4 1422.0 1312.6 1338.48.6 960.1 1092.1 1254.1 1290.0 1219.6 1384.0 1294.7 1268.38.8 895.1 1032.9 1203.2 1249.5 1130.5 1323.2 1277.7 1234.39 827.5 964.6 1125.1 1180.9 1104.6 1296.1 1239.7 1220.59.2 770.0 914.2 1087.7 1125.5 1071.0 1223.1 1198.0 1149.29.4 727.5 863.6 1034.6 1075.7 1005.6 1221.5 1145.0 1173.99.6 673.8 830.8 999.2 1063.3 980.1 1202.6 1108.3 1122.59.8 638.0 782.7 951.9 1006.7 950.7 1137.5 1058.4 1096.110 603.5 728.6 901.4 960.3 908.3 1094.5 1048.2 1064.9


Table F.6: Temperature data for the n-Decane fuel.

n-Decanex position z = 10 z = 20 z = 30 z = 40 z = 50 z = 60 z = 700 712.6 883.4 1076.6 1286.6 1499.5 1561.5 1828.60.2 715.2 891.4 1091.8 1280.2 1510.3 1564.6 1841.90.4 719.6 909.5 1087.7 1298.2 1503.5 1585.9 1840.40.6 726.5 931.0 1113.9 1317.1 1527.8 1580.3 1844.50.8 735.2 952.5 1123.8 1328.9 1523.9 1579.8 1833.81 747.7 983.3 1138.0 1346.2 1534.4 1603.6 1862.61.2 763.3 1014.3 1177.1 1385.5 1536.4 1609.9 1879.01.4 781.8 1051.5 1200.3 1423.7 1540.2 1626.5 1863.91.6 803.9 1084.1 1225.4 1457.8 1562.2 1625.5 1869.01.8 834.2 1121.2 1264.6 1479.4 1558.4 1698.5 1908.72 865.7 1160.0 1287.8 1491.9 1552.6 1717.1 1912.82.2 910.4 1202.5 1347.4 1520.5 1560.2 1735.1 1940.72.4 953.0 1250.1 1362.1 1552.1 1572.2 1936.5 1952.62.6 1002.7 1301.0 1413.8 1566.1 1614.7 1944.2 1949.32.8 1049.8 1348.1 1432.6 1591.1 1626.5 1967.8 1949.33 1108.0 1402.0 1454.0 1617.7 1681.5 1987.4 1953.63.2 1168.0 1442.8 1464.2 1617.3 1775.2 2017.8 1941.23.4 1223.9 1482.6 1489.5 1638.3 1826.2 2029.3 1904.93.6 1295.7 1517.3 1482.1 1673.0 1953.1 2026.6 1912.53.8 1366.7 1557.7 1527.8 1740.6 2019.6 1998.7 1890.14 1431.8 1593.2 1554.3 1871.1 2056.2 2008.4 1885.54.2 1497.3 1641.3 1600.7 1963.0 2062.3 1980.4 1853.54.4 1557.8 1717.1 1677.6 2031.7 2046.4 1923.3 1831.24.6 1611.7 1796.0 1973.7 2043.7 2028.2 1870.0 1829.84.8 1686.0 1892.5 2024.1 2040.0 2016.6 1872.7 1782.85 1772.8 1982.1 2033.3 1995.2 1934.8 1815.5 1763.05.2 1867.7 1990.1 2005.8 1954.3 1895.2 1766.8 1750.05.4 1928.0 1960.6 1964.9 1928.0 1854.3 1777.1 1724.15.6 1934.5 1909.6 1907.8 1887.9 1808.1 1692.1 1685.85.8 1881.1 1849.6 1861.7 1839.5 1728.8 1676.9 1661.56 1824.3 1806.2 1794.0 1797.6 1727.8 1663.9 1613.86.2 1741.6 1743.7 1752.4 1725.0 1681.9 1651.6 1576.86.4 1670.8 1682.2 1692.8 1690.5 1654.1 1602.8 1591.66.6 1601.1 1613.9 1651.9 1636.1 1597.1 1518.7 1541.86.8 1522.7 1555.0 1578.1 1591.6 1544.3 1528.1 1518.07 1430.2 1484.8 1514.2 1525.5 1469.8 1489.3 1463.57.2 1354.0 1425.0 1452.7 1486.4 1445.6 1419.9 1440.67.4 1284.9 1368.3 1376.0 1388.4 1399.4 1389.3 1401.37.6 1204.7 1313.9 1331.0 1374.2 1333.6 1355.5 1379.47.8 1147.4 1248.4 1266.1 1329.1 1329.3 1263.8 1324.68 1073.2 1189.4 1203.0 1254.2 1280.0 1266.9 1363.08.2 1005.2 1138.6 1160.6 1247.1 1227.2 1245.8 1274.28.4 951.2 1083.2 1115.8 1207.0 1205.2 1207.4 1257.08.6 887.7 1024.5 1043.4 1137.5 1179.4 1176.6 1243.58.8 841.1 982.8 1019.4 1088.1 1095.4 1144.6 1185.19 788.3 943.7 966.1 1045.9 1047.5 1109.9 1153.09.2 748.5 896.3 909.0 998.9 990.5 1076.5 1110.49.4 713.1 858.8 881.4 953.2 933.6 1043.0 1074.99.6 684.1 812.1 831.7 907.4 876.6 1009.6 1037.59.8 654.2 766.1 777.9 861.6 819.6 976.1 1000.210 673.5 720.3 697.3 815.8 762.7 942.7 962.9


Table F.7: Temperature data for the 1-Decene fuel.

1-Decenex position z = 10 z = 20 z = 30 z = 40 z = 50 z = 60 z = 700 743.0 885.9 1127.3 1363.9 1503.1 1548.6 1776.80.2 742.4 897.0 1145.5 1377.0 1509.8 1575.8 1778.40.4 740.5 909.4 1159.9 1365.4 1510.3 1569.7 1780.20.6 745.9 924.6 1155.2 1368.7 1506.0 1543.7 1762.00.8 757.1 942.4 1193.8 1376.6 1519.4 1559.4 1771.11 769.5 968.5 1208.2 1389.9 1510.5 1552.0 1775.51.2 787.4 997.0 1238.3 1399.5 1512.4 1550.5 1786.41.4 806.1 1022.0 1271.7 1430.7 1505.5 1554.0 1782.81.6 833.8 1055.9 1303.4 1433.2 1505.2 1543.5 1785.11.8 865.4 1098.8 1324.1 1448.6 1499.0 1572.2 1804.62 905.2 1129.4 1369.9 1470.1 1497.5 1571.6 1812.42.2 940.7 1159.4 1416.9 1486.3 1500.0 1620.5 1824.12.4 980.6 1205.7 1448.4 1501.9 1516.0 1625.5 1827.22.6 1032.5 1293.4 1482.8 1513.7 1507.4 1733.6 1825.52.8 1078.2 1335.2 1504.8 1535.0 1531.9 1740.6 1826.83 1136.4 1392.4 1543.8 1542.0 1561.6 1842.4 1819.43.2 1195.2 1437.9 1564.6 1542.3 1574.8 1874.8 1779.63.4 1240.5 1470.9 1575.0 1551.3 1602.5 1905.6 1808.03.6 1320.6 1534.7 1609.8 1582.4 1617.1 1925.0 1775.23.8 1378.7 1583.0 1669.3 1660.3 1695.8 1921.1 1771.64 1435.2 1594.2 1722.1 1802.6 1829.6 1899.5 1741.54.2 1492.5 1672.1 1895.3 1901.7 1931.7 1873.0 1753.44.4 1538.4 1738.9 1961.9 1959.1 1974.4 1864.7 1725.84.6 1607.1 1800.5 1971.8 2000.3 1981.6 1840.5 1728.14.8 1672.1 1872.2 1971.6 2005.2 1970.0 1816.0 1696.95 1787.9 1937.3 1948.3 2003.8 1972.1 1809.9 1671.65.2 1859.1 1960.8 1904.7 1969.2 1919.6 1794.7 1669.65.4 1905.0 1958.6 1877.7 1915.8 1902.8 1747.5 1628.05.6 1899.3 1938.8 1831.5 1897.2 1881.8 1722.8 1597.25.8 1848.6 1883.1 1774.4 1852.2 1859.7 1689.0 1593.46 1790.5 1824.4 1709.6 1806.1 1808.9 1675.6 1598.76.2 1722.6 1779.0 1667.7 1755.8 1788.4 1626.0 1511.66.4 1648.2 1703.2 1621.5 1702.7 1728.3 1617.7 1513.56.6 1568.7 1654.0 1539.4 1638.8 1672.9 1542.2 1499.56.8 1499.6 1586.2 1507.7 1600.4 1640.6 1550.1 1500.17 1424.4 1550.2 1465.3 1540.3 1589.0 1505.5 1438.37.2 1349.4 1458.6 1418.4 1515.0 1572.3 1469.8 1398.97.4 1284.9 1368.3 1376.0 1388.4 1399.4 1389.3 1401.37.6 1204.7 1313.9 1331.0 1374.2 1333.6 1355.5 1379.47.8 1147.4 1248.4 1266.1 1329.1 1329.3 1263.8 1324.68 1073.2 1189.4 1203.0 1254.2 1280.0 1266.9 1363.08.2 1005.2 1138.6 1160.6 1247.1 1227.2 1245.8 1274.28.4 951.2 1083.2 1115.8 1207.0 1205.2 1207.4 1257.08.6 887.7 1024.5 1043.4 1137.5 1179.4 1176.6 1243.58.8 841.1 982.8 1019.4 1088.1 1095.4 1144.6 1185.19 788.3 943.7 966.1 1045.9 1047.5 1109.9 1153.09.2 748.5 896.3 909.0 998.9 990.5 1076.5 1110.49.4 713.1 858.8 881.4 953.2 933.6 1043.0 1074.99.6 684.1 812.1 831.7 907.4 876.6 1009.6 1037.59.8 654.2 766.1 777.9 861.6 819.6 976.1 1000.210 673.5 720.3 697.3 815.8 762.7 942.7 962.9


Table F.8: Temperature data for the 5-Decene fuel.

5-Decenex position z = 10 z = 20 z = 30 z = 40 z = 50 z = 60 z = 700 717.3 887.1 1114.9 1388.0 1511.0 1653.1 1779.00.2 716.9 894.6 1113.4 1395.0 1507.6 1658.3 1778.30.4 717.1 904.9 1115.4 1382.2 1501.8 1626.1 1775.40.6 721.2 917.9 1120.6 1375.3 1500.6 1645.4 1770.90.8 723.0 938.3 1121.4 1395.2 1502.1 1614.8 1766.61 732.0 966.8 1144.2 1399.7 1507.3 1597.4 1747.11.2 741.8 996.0 1156.2 1403.6 1492.0 1599.9 1743.31.4 753.3 1027.5 1179.5 1426.5 1508.8 1637.7 1739.21.6 772.8 1059.7 1206.4 1428.3 1496.9 1610.3 1754.81.8 790.4 1093.9 1301.3 1451.0 1509.7 1679.5 1767.82 816.8 1126.1 1283.3 1465.0 1537.3 1686.4 1775.12.2 844.0 1174.6 1323.3 1468.4 1535.6 1645.1 1786.22.4 877.0 1222.7 1393.8 1470.5 1534.8 1705.1 1780.02.6 923.6 1276.1 1417.6 1506.0 1562.1 1698.4 1791.42.8 966.1 1308.9 1423.1 1494.7 1534.8 1731.5 1792.33 1021.6 1347.7 1464.9 1507.9 1654.9 1778.1 1787.53.2 1071.8 1385.8 1495.6 1526.0 1646.9 1808.8 1790.43.4 1120.7 1410.3 1525.0 1547.3 1794.2 1873.6 1756.83.6 1181.1 1438.8 1549.1 1602.1 1817.2 1880.1 1769.23.8 1258.6 1459.3 1563.5 1593.8 1903.5 1896.8 1749.04 1315.1 1465.9 1585.3 1691.2 1945.6 1904.1 1736.74.2 1388.5 1489.5 1663.9 1892.5 1958.7 1893.4 1727.54.4 1439.9 1522.9 1783.8 1961.9 1983.6 1874.9 1727.84.6 1486.0 1582.7 1896.1 2007.7 1970.3 1848.7 1699.74.8 1525.0 1697.0 1977.0 2003.4 1949.2 1832.8 1687.95 1579.8 1843.9 1995.8 1965.5 1895.5 1801.3 1656.95.2 1643.7 1966.8 1977.2 1931.4 1903.1 1775.1 1643.35.4 1732.4 1947.8 1937.0 1891.9 1884.0 1749.3 1628.95.6 1880.7 1903.4 1889.2 1859.1 1845.4 1714.0 1620.85.8 1949.3 1848.8 1842.4 1832.3 1771.2 1686.4 1577.96 1925.1 1785.7 1789.1 1760.0 1751.4 1674.4 1538.56.2 1859.8 1727.1 1735.3 1709.8 1713.7 1623.1 1532.06.4 1782.6 1645.0 1691.5 1636.3 1675.7 1599.3 1489.26.6 1715.6 1587.8 1635.3 1620.1 1617.6 1573.8 1488.96.8 1632.4 1524.0 1578.1 1551.9 1601.2 1529.7 1447.77 1547.2 1464.2 1524.3 1524.3 1511.0 1492.2 1438.07.2 1462.1 1385.2 1462.9 1486.2 1480.4 1475.9 1414.47.4 1376.9 1331.3 1405.3 1419.1 1463.4 1407.5 1375.97.6 1304.9 1265.1 1351.1 1367.5 1401.3 1389.1 1331.87.8 1215.6 1206.1 1292.1 1315.8 1334.0 1354.9 1311.78 1134.9 1148.4 1240.7 1281.9 1310.8 1326.9 1268.58.2 1058.5 1071.3 1184.5 1239.8 1238.6 1291.6 1265.88.4 992.4 1018.6 1134.1 1184.3 1208.4 1242.4 1265.48.6 923.6 967.0 1081.2 1179.5 1170.4 1195.9 1225.48.8 862.7 917.4 1029.2 1080.9 1143.6 1215.0 1105.89 802.5 859.2 980.0 1080.9 1108.8 1146.5 1054.79.2 749.3 812.6 937.8 1007.1 1040.2 1121.2 1088.79.4 710.3 776.2 899.8 949.3 997.0 1054.0 1055.19.6 673.3 736.9 853.5 942.9 968.9 1027.5 1010.19.8 637.2 699.0 812.1 892.3 944.7 985.2 992.010 609.6 663.7 770.1 859.7 891.2 949.1 964.3

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