EUROPEAN COMMISSION DG MOVE - LNG BClngbc.eu/system/files/deliverable_attachments/LNG BC_D_3.11_Studies regarding Ageing of...EUROPEAN COMMISSION DG MOVE SEVENTH FRAMEWORK PROGRAMME

EUROPEAN COMMISSION

DG MOVE

SEVENTH FRAMEWORK PROGRAMME

GC.SST.2012.2-3 GA No. 321592

Studies regarding Ageing of Fuel

LNG Blue Corridors Project is supported by the European Commission under the Seventh Framework

Programme (FP7). The sole responsibility for the content of this document lies with the authors. It does

not necessarily reflect the opinion of the European Union. Neither the FP7 nor the European

Commission is responsible for any use that may be made of the information contained therein.

Deliverable No. LNG BC D3.11

Deliverable Title Studies regarding Ageing of Fuel

Dissemination level Public

Written By Stefan Ernebrant (E.ON Gas)

Tobias Johansson (E.ON Gas)

April 2017

Checked by Björn Fredriksson Möller (E.ON Gas)

Dorian González (GNF)

July 2017

Approved by Judith Dominguez, Javier Lebrato (IDIADA) July 2017

Issue date 11/08/2017

LNG-BC D3.11 – Studies regarding Ageing of Fuel Public

2

REVISION HISTORY AND STATEMENT OF

ORIGINALITY Revision History

Rev Date Author Organization Description

0.1 April ‘17 Björn Fredriksson Möller E.ON Gas Mainly editing and rephrasing

0.2 July’17 Javier Lebrato IDIADA General Revision

Statement of originality:

This deliverable contains original unpublished work except where clearly indicated

otherwise. Acknowledgement of previously published material and of the work of others

has been made through appropriate citation, quotation or both.


3

Executive Summary E.ON Gas Sverige AB has got the opportunity to participate and present one of the deliverables to the

LNG Blue Corridors Project. The LNG Blue Corridor Project is a European project organized by NGVA

Europe and is financed by the Seventh Framework Programme (FP7). This study regard aging of

Liquefied Natural Gas (LNG) constitutes the 11th

deliverable within the third work package of the LNG

Blue Corridor Project.

The project started with a literature study where reports and articles were evaluated. The literature

study is the basis of the report. Following the literature study, several phone interviews with people

with experience of ageing were performed. Most of the knowledge received in the literature study was

confirmed by the phone interviews and further information was also gained. Calculation examples

were performed to show in a comprehensive way how fast ageing of LNG is completed as a function of

the heat leakage rate. At last the results from the literature study, phone interviews and example

calculations were compiled into this report.

The objectives of this report are to analysis and clarify the LNG ageing phenomena.

The report summarize that ageing is a gradual change in the initial composition of the liquid over a

period of time i.e. ageing occurs due to evaporation of boil-off gas. It also illustrates that LNG with a

high content of heavier hydrocarbons has a high tendency to age. Thus ageing affects the composition

of LNG but has only minor effect on the composition of the LBG. The report describes that ageing

decreases the methane number and increases the heating value. It implies that the risk of damaging

the engine is more probable when ageing has occurred i.e. has reduced the methane number outside

the recommended range. In this report is it also stated that the original of LNG have a greater impact

on methane number than the effects of ageing.


4

Contents Executive Summary ................................................................................................................................. 3

1 Introduction ..................................................................................................................................... 6

1.1 Background .............................................................................................................................. 6

1.1.1 LNG Blue Corridors Project .............................................................................................. 6

1.1.2 Ageing of LNG .................................................................................................................. 7

1.2 Objectives ................................................................................................................................ 7

1.2.1 LNG Blue Corridor Project ............................................................................................... 7

1.2.2 Ageing of LNG .................................................................................................................. 7

1.3 Limitations ............................................................................................................................... 7

2 Theory .............................................................................................................................................. 8

2.1 Composition of LNG and LBG .................................................................................................. 8

2.2 Methane number .................................................................................................................... 9

2.3 Boil-off ..................................................................................................................................... 9

2.4 Ageing/Weathering ................................................................................................................. 9

2.5 Roll-Over .................................................................................................................................. 9

2.6 Knocking .................................................................................................................................. 9

3 Methodology ................................................................................................................................. 11

4 Result ............................................................................................................................................. 12

5 Discussion and conclusions ........................................................................................................... 15

5.1 Initiation of roll-over ............................................................................................................. 15

5.2 Increased risk of ageing in small tanks .................................................................................. 15

5.3 Time to fulfil ageing ............................................................................................................... 15

5.4 Differences in ageing between LNG and LBG ........................................................................ 16

5.5 Methods to prevent or revers ageing ................................................................................... 16

5.5.1 Re-liquefy ....................................................................................................................... 16

5.5.2 Mathematic analysis to prevent ageing ........................................................................ 16

5.5.3 Refuelling by re-liquefy boil-off gas ............................................................................... 16

5.6 Consequences of ageing ........................................................................................................ 17

5.6.1 Knocking ........................................................................................................................ 17

5.6.2 Environmental challenges ............................................................................................. 17

5.7 Conclusions ............................................................................................................................ 17

5.8 Future Work .......................................................................................................................... 17


5

6 Bibliography ................................................................................................................................... 18


6

1 Introduction E.ON Gas Sverige AB has got the opportunity to participate and present one of the deliverables to the

LNG Blue Corridors Project. The LNG Blue Corridor Project is a European project organized by NGVA

Europe and is financed by the Seventh Framework Programme (FP7). This study regard aging of

Liquefied Natural Gas (LNG) constitutes the 11th

deliverable within the third work package of the LNG

Blue Corridor Project.

1.1 Background

E.ON Gas Sverige AB strives to be in the forefront of development in the gas business and therefor is it

a matter of course to take part in European projects to develop and strengthen the competitiveness of

gas as a propellant. The LNG Blue Corridors Project fulfils E.ONs guidelines of development and is a

step in the right direction to handle the environmental challenges that the world stands in front of.

1.1.1 LNG Blue Corridors Project

The LNG Blue Corridors project’s object is to establish LNG as a real alternative for medium- and long-

distance transport—first as a complementary fuel and later as an adequate substitute for diesel. Up to

now the common use of gas as fuel has been for heavy vehicles running on natural gas (NG) only for

municipal use, such as urban buses and garbage collection trucks. In both types of application, engine

performance and autonomy are good with present technologies, as they are well adapted to this

alternative cleaner fuel.

However, analysing the consumption data, the equivalence in autonomy of 1 liter of diesel oil is 5 liters

of CNG (Compressed Natural Gas), compressed to 200 bar. Five times more volume of fuel prevents

the use of CNG in heavy road transport, because its volume and weight would be too great for a long-

distance truck. This opens the way for LNG (Liquefied Natural Gas), which is the way natural gas is

transported by ship to any point of the globe. NG liquefies at 162ºC below zero and the cost in energy

is only 5% of the original gas. This state of NG gives LNG the advantage of very high energy content.

Only 1.8 liters of LNG are needed to meet the equivalent autonomy of using 1 liter of diesel oil. A 40-

ton road tractor in Europe needs a tank of 400 to 500 liters for a 1.000 km trip; its equivalent volume

with liquid gas would be 700 to 900 liters of LNG, a tank dimension that could easily be fitted to the

side of the truck chassis. LNG therefore opens the way to the use of NG for medium- and long-

distance road transport.

LNG has huge potential for contributing to achieving Europe’s policy objectives, such as the

commission’s targets for greenhouse gas reduction, air quality targets, while at the same time reducing

dependency on crude oil and guaranteeing supply security. Natural gas heavy-duty vehicles already

comply with Euro V emission standards and have enormous potential to reach future Euro VI emission

standards, some without complex exhaust gas after-treatment technologies, which have increased

procurement and maintenance costs.

To meet the objectives, a series of LNG refuelling points have been defined

along the four corridors covering the Atlantic area (green line), the

Mediterranean region (red line) and connecting Europe’s South with the

North (blue line) and its West and East (yellow line) accordingly. In order to

implement a sustainable transport network for Europe, the project has set

the goal to build approximately 14 new LNG stations, both permanent and

Figure 1-1. Impression of the

LNG Blue Corridors


7

mobile, on critical locations along the Blue Corridors whilst building up a fleet of approximately 100

Heavy-Duty Vehicles powered by LNG.

This European project is financed by the Seventh Framework Programme (FP7), with the amount of

7.96 M€ (total investments amounting to 14.33 M€), involving 27 partners from 11 countries.

http://www.lngbluecorridors.eu/.

1.1.2 Ageing of LNG

The demand and interest of liquid fuels continues to grow and to ensure continuous supply, a priority

is to guarantee high quality of fuels during long term storage [1]. Vessels, trucks and stationary tanks

are common places where long term storage is utilized. It is therefore important to understand how

LNG is ageing during time to ensure a certain quality of LNG is delivered after storage.

This study regard aging of LNG constitutes the 11th

deliverable within the third work package of the

LNG Blue Corridor Project.

1.2 Objectives

1.2.1 LNG Blue Corridor Project

The primary objectives of the LNG Blue Corridors Project are to utilize the expertise of industrial

partners and research institutes in LNG transport and infrastructure technology to roll out a network of

LNG refuelling points and to aid the market development of heavy-duty vehicles running on natural

gas.

1.2.2 Ageing of LNG

The objectives of this report are to analysis and clarify the LNG ageing phenomena.

1.3 Limitations

This report concentrates on methods that reduce the ageing process of LNG i.e. reduce the

evaporation of boil off gas. Other methods that only reduce the environmental impact by taking care

of the boil off gas are neglected.

Performed calculations are computed to illustrate in a comprehensive way the change in methane

number caused by boil-off effect as a function of time. More thoroughly computed calculations are

not included in this report.


8

2 Theory The purpose of this section is to make the reading process easier by describing topics that are

addressed in this report thoroughly.

2.1 Composition of LNG and LBG

LNG is natural gas that is cooled down to liquid phase, about -160 °C at atmospheric pressure. LBG is

bio gas cooled down to liquid phase. LNG/LBG is a colorless and odorless liquid. The composition of

LNG/LBG can vary depending on the source and the method of liquidation, but methane is the main

component in all LNG/LBG. Except from methane, LNG can contain heavier hydrocarbons like ethane,

propane, butane and pentane, and also nitrogen. Table 1 below describes the composition, heating

value and Wobbe Index of LNG from different countries. LBG typically contains no heavier

hydrocarbon at all, but methane and only small parts of nitrogen.

Table 1 – Worldwide average LNG compositions.

Worldwide average LNG compositions

Nitrogen Methane Ethane Propane

Higher

HC

Gross/High

Heat value

Wobbe

index

Methane

number

% % % % % MJ/Sm3 MJ/Sm

3 -

USA-Alaska 0,17 99,74 0,08 0,01 0,00 37,75 50,62 99,6

Trinidad 0,03 96,82 2,74 0,31 0,10 38,82 51,29 89,2

Egypt-Damietta 0,08 97,70 1,80 0,22 0,20 38,39 51,03 88,9

Egypt-Idku 0,00 97,20 2,30 0,30 0,20 38,61 51,19 88,9

Algeria-Bethioua 2 0,92 91,39 7,17 0,52 0,00 39,78 51,41 81,0

Algeria-Skikda 1,02 91,19 7,02 0,66 0,11 39,87 51,42 79,9

Indonesia-Arun 0,06 91,16 6,01 1,84 0,93 41,32 52,64 72,9

Algeria-Arzew 0,56 87,98 9,00 1,99 0,47 41,68 52,62 72,6

Abu Dhabi 0,29 84,77 13,22 1,63 0,09 42,45 53,16 72,1

Algeria-Bethioua 1 1,20 87,59 8,39 2,12 0,70 41,01 51,96 71,6

Malaysia 0,16 91,15 4,96 2,79 0,94 41,52 52,70 71,5

Qatar 0,36 90,10 6,23 2,32 0,99 41,58 52,65 71,4

Nigeria 0,08 91,28 4,62 2,62 1,40 41,76 52,87 69,9

Austraia-NWS 0,09 87,39 8,33 3,35 0,84 42,74 53,40 69,1

Brunei 0,05 90,61 4,97 2,89 1,48 42,09 53,06 68,8

Oman 0,35 87,89 7,27 2,92 1,57 42,73 53,27 67,2

Indonesia-Badak 0,02 89,76 5,06 3,54 1,62 42,61 53,34 67,0

Libya 0,69 81,57 13,38 3,67 0,69 44,02 53,82 66,7

Sources: NGVA Europe Position Paper: LNG Fuel for all Transport Models, Methane number calculated

according to DNVGL, https://pkicalculator.dnvgl.com

More information about gas quality of LNG and LBG can be found in Work Package 3.2 of this project.


9

2.2 Methane number

The methane number defines the natural gas fuel´s resistance against knocking in a piston engine. The

methane number for natural gas fuel is similar to the octane number for other fuels. A fuel with 100%

methane has a methane number of 100. The more amounts of heavier hydrocarbons a fuel contains,

the lower methane number [2].

2.3 Boil-off

LNG is a cryogenic liquid i.e. a low temperature liquid with a boiling point around -160°C. Inevitable

heat enters from the surroundings and warms the liquid even though the tank is equipped with high

insulation and double walls etc. The increasing temperature implies that the liquid approaches its

boiling point and eventually evaporates. This phenomenon is known as boil-off and is abbreviated

BOG (Boil-Off Gas). As previous mentioned in chapter 2.2, LNG consist of different components with

associated boiling points. Components with a low boiling point will be evaporated first such as

nitrogen and methane and components as heavier hydrocarbons such as ethane, propane and butane

will boil off later [3].

2.4 Ageing/Weathering

LNG ageing or weathering as it also can be named is a gradual change in the initial composition of the

liquid over a period of time. The phenomenon occurs due to heat transfer from the surroundings

which initiates evaporation of the stored liquid and hence gives boil-off gas. The composition of the

liquid change in terms of an increased content of heavier components due to that the volatile

components in the liquid evaporate. During the ageing process both quality and properties of the

liquid are changed. This is known as ageing of fuel.

2.5 Roll-Over

Stratification in tanks is a phenomenon that occurs due to differences in density. The stratification is

commonly initiated by boil-off or when a new liquid with a different density is injected to a partly filled

tank. The warmer liquid is rising to the top where it eventually is evaporated by heat transfer from the

surroundings. In the top layer after the lighter gases are evaporated, the remaining liquid in top layer

becomes denser. At the same time the liquid in the bottom layer becomes warmer and rises to the

area where the top layer merges with the bottom layer. However the liquid in the bottom layer cannot

evaporate due the pressure head created by the top layer. The bottom layer continues to become

warmer i.e. lighter and the two liquids densities approach each other until they are rapidly mixed.

When the mixing occurs the bottom layer is superheated which realise large amount of vapour

creating a large pressure increase. This phenomenon is known as roll-over.

The pressure increased created by roll-over could lead to damages to the tank and the corresponding

systems such as over-pressurization of the tank or that the relief system of the tank may not be able to

handle the rapid increase of boil-off gas.

One should note that stratification can be used to reduce production of boil-off gas but must at the

same time be monitored thoroughly to not initiate roll-over [4].

2.6 Knocking

Engine knocking is when the combustion process in the cylinder of the combustion engine occurs

when the piston is not in the optimal position for combustion, e.g. before the piston has reached the


10

highest point. Knocking comes when the fuel pre ignites from the heat caused by the compression in

the cylinder instead of being ignited from the spark plug. Knocking causes shock waves of high

pressure in the cylinder and can cause huge damage inside the engine. The name “knocking” comes

from the sound when the pre ignition occurs.


11

3 Methodology In this section insight into different procedures that have been executed during the research is given. It

serves to provide an understanding of the decisions that were made during this research about ageing

of LNG.

The project started with a literature study where reports and articles were evaluated. The literature

study is the basis of the report. Following the literature study, several phone interviews with people

with experience of ageing were performed. Most of the knowledge received in the literature study was

confirmed by the phone interviews and further information was also gained. Following persons

participated during phone interviews:

• Bo Winberg (Euromekanik)

• Torgny Eriksson (Teramek)

• Lars Ohlson (Fordonsgas Sverige)

Calculation examples were performed to show in a comprehensive way how fast ageing of LNG is

completed as a function of the heat leakage rate. Three web based calculation programs where used in

the calculations, programs from DNV GL [5], Wärtsilä [6] and Cummins Westport [7]. Results from the

calculations are illustrated in the result chapter.

At the beginning of the calculation a start composition of the LNG fuel and a boil-off rate (%w per day)

is defined. The assumption is made that the boil-off from LNG only consists of methane, resulting in

only a reduction of methane in the liquid fuel. After each day a new fuel composition is calculated,

based on the reduced amount of methane and a constant amount of higher hydrocarbons, in this case

ethane and propane. The fuel composition from each day is then used for calculating the methane

number of the fuel. When calculating the methane number, three public web based programs were

used. The methane number is then plotted as a function of time (days). Data for actual boil-off rates

has not been available for this report, but a realistic rule-of-thumb value for large storage tanks of

0,1% has been used. In the low-end scale of storage tanks 1% boil-off rate has been chosen. A further

study to follow-up on actual boil-off rates with different gas compositions is recommended.

The same procedure is used when analysing LBG, with the only difference that the assumption is made

that the fuel only contains methane.

At last the results from the literature study, phone interviews and example calculations were compiled

into this report.


12

4 Result Four different calculations were made, each calculation with different combinations of LNG fuel

specification and different boil-off rates. The fuel specifications and boil-off rates were:

Calculation 1

• Fuel specification: 90% CH4, 7% C2H6 and 3% C3H8.

• Boil-off rate 1% of the methane per day.

• See result from the calculation in diagram 1.

Calculation 2

• Fuel specification: 97% CH4 and 3% C2H6.

• Boil-off rate 1% of the methane per day.


Calculation 3

• Fuel specification: 90% CH4, 7% C2H6 and 3% C3H8.

• Boil-off rate 0.1% of the methane per day.


Calculation 4

• Fuel specification: 90% CH4 and 3% C2H6.

• Boil-off rate 0.1% of the methane per day.


Figure 1 - The first calculation of methane number as a function of days with boil-off.


13

Figure 2 - The second calculation of methane number as a function of days with boil-off.

Figure 3 - The third calculation of methane number as a function of days with boil-off.


14

Figure 4 - The fourth calculation of methane number as a function of days with boil-off.


15

5 Discussion and conclusions 5.1 Initiation of roll-over

As previously mentioned in the theory chapter roll-over occurs when two liquids with different density

rapidly are mixed in a tank. The stratification which could lead to roll-over is commonly initiated by

boil-off or when a new liquid with a different density is injected to a partly filled tank. According to

literature and performed phone interviews it seems roll-over occurs exclusively in large tanks and is

not a common problem in tanks for trucks etc. However most of the trucks refills once a day which

implies that the fuel is renewed continuously and at the same time is mixed. The fact that the truck is a

moving unit affects the mixing process of the fuel. Theoretically could roll-over occur in a truck tank

but no accidents are known by the authors.

The best way to prevent roll-over is to continuously use the vehicle by consuming fuel; both problem

regard ageing and consequences as roll-over appear mostly when the vehicle has not been used for a

long period of time.

Unless LNG is stored in tanks for an extended period of time there is no need for further analysis of

this phenomena.

5.2 Increased risk of ageing in small tanks

The risk of ageing is greater with small tanks due to that the metal coating constitutes a large part in

comparison to the stored liquid. The large metal coating implies a large surface for heat transfer i.e.

large heat leakage from the tank to the surroundings. It is also more cost efficient to invest in systems

to prevent ageing in large applications than in small e.g. re-liquefy boil-off gas and transfer it back to

the truck tank. However, some truck manufacturers are providing system for preventing ageing in

there new models of trucks [8].

5.3 Time to fulfil ageing

In this report calculations have been made describing how the methane number of LNG fuel over time

is affected by the boil-off from an LNG tank.

For larger stationary LNG-tanks, an average boil-off rate of 0.1% methane per day is set and for smaller

LNG-tanks on trucks an average boil-off rate of 1% methane is used.

The calculations shows that if the boil-off rate is 1% per day and the fuel from the beginning contains

90% methane and 10% heavier hydro carbons, the methane number decreases between 0.5 and 1.0

units per day (Calculation 1 in chapter 4). With the same fuel, but a boil-off rate of only 0.1%, the

decrease in methane number is only about 0.1 units per day (Calculation 3 in chapter 4). If the

methane content is higher from the beginning, the methane number drops a bit more rapid, due to

the higher methane content (Calculation 2 and 4 in chapter 4).

The calculations show that ageing of LNG has an influence on the methane number of the fuel over

time in smaller vehicle tanks, but probably not in larger tanks with smaller boil-off rates.

The analysis does also show that, from a methane number perspective, it is more important to define

the initial quality of the LNG compared to the quality change cause by ageing. It is important that the

methane number in the fuel already when coming from the LNG source has a specification that is

corresponding to the application where the LNG shall be used. E.g. engines that cannot handle


16

methane numbers below 75, should not use LNG fuels with the specification used in calculation 1 and

3.

When the methane level is low enough to be harmful for the engine differs from engine to engine.

Accepted methane level in the fuel does also differ by country, mainly defined by the quality of the gas

supplied in the specific geographical region. Minimum accepted methane number in FPrEN 16723-2

(Natural gas and biomethane for use in transport and biomethane for injection in the natural gas

network - Part 2: Automotive fuels specification) is 65.

5.4 Differences in ageing between LNG and LBG

As already concluded in this report, ageing of LNG that is harmful for truck engines depends on the

amount of heavier hydrocarbons in the fuel. The more amounts of heavier hydrocarbons, the higher is

the risk for harmful ageing of the fuel.

Compared to LNG, LBG does not contain any heavier hydro carbons, but only methane and small parts

of nitrogen and oxygen, thus LBG is not affected by ageing that is harmful for truck engines.

5.5 Methods to prevent or revers ageing

5.5.1 Re-liquefy

Once the evaporation of gas from LNG has started, the liquid phase starts to change specification. The

only way to keep the original specification of the LNG, is to re-cool the gas phase back to liquid phase

and insert the liquid into the tank again. This is called re-liquefy. Re-liquefy can be used when it is

important to keep the specification of the fuel constant, or when boil-off to the atmosphere must be

minimized and there is no other solution available to prevent the boil-off from the system.

5.5.2 Mathematic analysis to prevent ageing

Several companies are using mathematic analysis to calculate effects of ageing as a function of time

based on mass and energy balance. A simplified method to solve the above stated problem is by using

a thermophysical property prediction method. Using mathematical models enables to monitor the

ageing process in different types of storage and may be used as a tool to prevent the effect of the

ageing process.

Further information on the methods above can be found in literature [9].

5.5.3 Refuelling by re-liquefy boil-off gas

Refuelling of a LNG tank can be utilized to reduce boil-off gas in the tank by injecting cold LNG at the

top of the tank to liquefy the boil-off gas. Tanks where this refuelling method is applied to need to be

equipped with two refilling nozzles; one placed at the top of the tank and one at the bottom. The

nozzle placed at the top is used at the start of the refuelling process to liquefy the boil-off gas and the

bottom nozzle is used later for further refuelling. This refuelling method is well known and has shown

great potential to reduce boil-off gas.


17

5.6 Consequences of ageing

5.6.1 Knocking

Ageing of LNG fuel decreases the amount of methane in the fuel and hence affects the methane

number of the fuel that is left in the LNG-tank. A fuel with lower methane number has a decreased

ability to prevent knocking. Lowest possible methane number for a specific engine to prevent knocking

differs from engine manufacturer and from engine type. EUROMOT (The European Association of

Internal Combustion Engine Manufacturers) states in a report [10] that their recommended minimum

methane level for a combustion engine is 80. The same report claims that similar limit value in US is 75.

The pre ignition in the cylinder causes a very high pressure in the cylinder, which can complete

damage the engine.

5.6.2 Environmental challenges

If boil-off gas from the ageing process is released into the atmosphere by a relief valve, environmental

deleterious substances is let out into the atmosphere e.g. methane. Methane is a greenhouse gas and

is 34 times more potent than carbon dioxide [11]. However methane does not linger as long in the

atmosphere than carbon dioxide.

The loss of fuel by ageing is another environmental disadvantage. The evaporated fuel must be

replaced with new processed LNG. However this aspect is just applicable when a truck has been

park/unused for a long period of time e.g. several months.

5.7 Conclusions

Conclusions are drawn in relation to earlier work.

• Ageing is a gradual change in the initial composition of the liquid over a period of time i.e.

ageing occurs due to evaporation of boil-off gas.

• LNG with a high content of heavier hydrocarbons has a high tendency to age.

• Ageing affects the composition of LNG i.e. it includes heavier hydrocarbons, but has only a

minor effect on the composition of the LBG i.e. LBG mainly consist of methane.

• Ageing decreases the methane number and increases the heating value.

• Truck engines are recommended to operate in a range based on methane number. The

risk of damage to the engine is more probable when ageing has occurred i.e. has reduced

the methane number outside the recommended range.

• The original of LNG have a greater impact on methane number that the effects of ageing.

The high content of methane in LBG is an advantage compared to LNG.

5.8 Future Work

The following course of action is suggested as future work:

• Investigate and analyse how truck engines can be operated outside the recommended

methane number range.

• Experimental verification of how the boil-off effects the fuel composition as a function of

time, including actual boil-off rates.


18

6 Bibliography [1] Liquid Fuel Ageing Processes in Long-term Storage Conditions [Internet]. [Place unknown]:

INTECH; 2015 [cited 2017 Mars 29]. Available from: https://www.intechopen.com/books/storage-

stability-of-fuels/liquid-fuel-ageing-processes-in-long-term-storage-conditions

[2] Alvarez Henrik. Energigasteknik. Lund: Studentlitteratur; 1990.

[3] Benito Angel. Accurate determination of LNG quality unloaded in. Barcelona: Enagás, S.A;-.

[4] [Unknown]. Rollover in LNG Storage Tanks. Second edition. Paris: International Group of Liquefied

Natural Gas Importers; 2015.

[5] PKI Methane Number Calculator for LNG [Internet]. [Place unknown]: DNV GL 2017 [cited 2017

Mars 29]. Available from: https://www.dnvgl.com/oilgas/natural-gas/fitness-for-purpose-of-lng-pki-

methane-number-calculator.html

[6] Wärtsilä methane number calculator [Internet]. [Place unknown]: Wärtsilä 2017 [cited 2017 Mars

29]. Available from: https://www.wartsila.com/products/marine-oil-gas/gas-solutions/methane-

number-calculator

[7] Fuel Quality Calculator [Internet]. [Place unknown]: Cummins Westport 2017 [cited 2017 Mars 29].

Available from: http://www.cumminswestport.com/fuel-quality-calculator

[8] Gunnarsson Linda, Helander Erik. How to Handle Boil-off Gases from LNG Trucks. Södertälje:

Linköping University; 2015.

[9] Timmerhaus K.D. Advances in Cyrogenic Engineering volume 19. Colorado: Springer

Science+Business; 1995.

[10] Technical Statement on Commercial Natural Gas in CNG- and LNG Fueled Mobile Heavy-Duty

Engine Applications [Internet]. [Place unknown]: Truck & Engine Manufactures Association; 2014 [cited

2017-04-13]. Available from: https://www.intechopen.com/books/storage-stability-of-fuels/liquid-fuel-

ageing-processes-in-long-term-storage-conditions

[11] Faktablad: Växthuseffekten [Internet]. [Place unknown]: Naturskyddsföreningen; 2017 [cited 2017

Mars 29]. Available from: http://www.naturskyddsforeningen.se/skola/energifallet/faktablad-

vaxthuseffekten

Documents

EUROPEAN COMMISSION DG MOVE - LNG BClngbc.eu/system/files/deliverable_attachments/LNG BC_D_3.11_Studies regarding Ageing of...EUROPEAN COMMISSION DG MOVE SEVENTH FRAMEWORK PROGRAMME