Effects of molar expansion ratio of fuels on engine efficiency

Duc Khanh Nguyen; James Szybist; Louis Sileghem; Sebastian Verhelst

doi:10.1016/j.fuel.2019.116743

Effects of molar expansion ratio of fuels on engine efficiency

Duc Khanh Nguyen, James Szybist, Louis Sileghem, Sebastian Verhelst

Buildings and Transportation Science Div

Research output: Contribution to journal › Article › peer-review

16 Scopus citations

Abstract

Fuel properties have a strong impact on the efficiency of internal combustion engines. Contrary to other physical and thermochemical fuel properties, the molar expansion ratio is normally ignored. Molar expansion ratio is the ratio of number of moles of the products to the reactants. In this work, the impact of the fuel's molar expansion ratio on engine efficiency is investigated. Findings are based on simulations of a spark ignition engine using different fuels (standard fuels and user-defined fuels) and different dilution ratios. Simulations without heat transfer and friction were performed first. The combustion then takes place at top dead center with a very short combustion duration to approach the ideal Otto cycle. The heat transfer and friction were then added step by step. From this analysis, it could be concluded that the heat loss and friction work decrease as molar expansion ratio increases. The gross indicated and brake thermal efficiencies thus increase. User-defined fuels with different molar expansion ratio, but the same physical and thermochemical properties were then employed. The simulated results showed that the brake thermal efficiency increases by around 1.15% with an increase in molar expansion ratio of 0.02 compared to a fuel with a molar expansion ratio of unity. The simulation was also done with air and exhaust gas recirculation dilution.

Original language	English
Article number	116743
Journal	Fuel
Volume	263
DOIs	https://doi.org/10.1016/j.fuel.2019.116743
State	Published - Mar 1 2020

Funding

The financial supports from the Special Research Fund (BOF) of Ghent University (Grant No. 01N03013 ) and GOA project (BOF16/GOA/004) are gratefully acknowledged. The authors also acknowledge the support of the US Department of Energy Vehicle Technologies Office, particularly program managers Gurpreet Singh and Mike Weismiller. This manuscript has been authored in-part by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

Funders	Funder number
US Department of Energy Vehicle Technologies Office
UT-Battelle
Universiteit Gent	01N03013, BOF16/GOA/004
Bijzonder Onderzoeksfonds

Keywords

Energy losses
Engine efficiency
Fuel properties
Molar expansion ratio
Spark-ignition engines

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10.1016/j.fuel.2019.116743

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title = "Effects of molar expansion ratio of fuels on engine efficiency",

abstract = "Fuel properties have a strong impact on the efficiency of internal combustion engines. Contrary to other physical and thermochemical fuel properties, the molar expansion ratio is normally ignored. Molar expansion ratio is the ratio of number of moles of the products to the reactants. In this work, the impact of the fuel's molar expansion ratio on engine efficiency is investigated. Findings are based on simulations of a spark ignition engine using different fuels (standard fuels and user-defined fuels) and different dilution ratios. Simulations without heat transfer and friction were performed first. The combustion then takes place at top dead center with a very short combustion duration to approach the ideal Otto cycle. The heat transfer and friction were then added step by step. From this analysis, it could be concluded that the heat loss and friction work decrease as molar expansion ratio increases. The gross indicated and brake thermal efficiencies thus increase. User-defined fuels with different molar expansion ratio, but the same physical and thermochemical properties were then employed. The simulated results showed that the brake thermal efficiency increases by around 1.15% with an increase in molar expansion ratio of 0.02 compared to a fuel with a molar expansion ratio of unity. The simulation was also done with air and exhaust gas recirculation dilution.",

keywords = "Energy losses, Engine efficiency, Fuel properties, Molar expansion ratio, Spark-ignition engines",

author = "Nguyen, {Duc Khanh} and James Szybist and Louis Sileghem and Sebastian Verhelst",

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year = "2020",

month = mar,

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doi = "10.1016/j.fuel.2019.116743",

language = "English",

volume = "263",

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T1 - Effects of molar expansion ratio of fuels on engine efficiency

AU - Nguyen, Duc Khanh

AU - Szybist, James

AU - Sileghem, Louis

AU - Verhelst, Sebastian

PY - 2020/3/1

Y1 - 2020/3/1

N2 - Fuel properties have a strong impact on the efficiency of internal combustion engines. Contrary to other physical and thermochemical fuel properties, the molar expansion ratio is normally ignored. Molar expansion ratio is the ratio of number of moles of the products to the reactants. In this work, the impact of the fuel's molar expansion ratio on engine efficiency is investigated. Findings are based on simulations of a spark ignition engine using different fuels (standard fuels and user-defined fuels) and different dilution ratios. Simulations without heat transfer and friction were performed first. The combustion then takes place at top dead center with a very short combustion duration to approach the ideal Otto cycle. The heat transfer and friction were then added step by step. From this analysis, it could be concluded that the heat loss and friction work decrease as molar expansion ratio increases. The gross indicated and brake thermal efficiencies thus increase. User-defined fuels with different molar expansion ratio, but the same physical and thermochemical properties were then employed. The simulated results showed that the brake thermal efficiency increases by around 1.15% with an increase in molar expansion ratio of 0.02 compared to a fuel with a molar expansion ratio of unity. The simulation was also done with air and exhaust gas recirculation dilution.

AB - Fuel properties have a strong impact on the efficiency of internal combustion engines. Contrary to other physical and thermochemical fuel properties, the molar expansion ratio is normally ignored. Molar expansion ratio is the ratio of number of moles of the products to the reactants. In this work, the impact of the fuel's molar expansion ratio on engine efficiency is investigated. Findings are based on simulations of a spark ignition engine using different fuels (standard fuels and user-defined fuels) and different dilution ratios. Simulations without heat transfer and friction were performed first. The combustion then takes place at top dead center with a very short combustion duration to approach the ideal Otto cycle. The heat transfer and friction were then added step by step. From this analysis, it could be concluded that the heat loss and friction work decrease as molar expansion ratio increases. The gross indicated and brake thermal efficiencies thus increase. User-defined fuels with different molar expansion ratio, but the same physical and thermochemical properties were then employed. The simulated results showed that the brake thermal efficiency increases by around 1.15% with an increase in molar expansion ratio of 0.02 compared to a fuel with a molar expansion ratio of unity. The simulation was also done with air and exhaust gas recirculation dilution.

KW - Energy losses

KW - Engine efficiency

KW - Fuel properties

KW - Molar expansion ratio

KW - Spark-ignition engines

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Effects of molar expansion ratio of fuels on engine efficiency

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Keywords

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