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Effects of molar expansion ratio of fuels on engine efficiency

Nguyen, Duc Khanh ; Szybist, James ; Sileghem, Louis and Verhelst, Sebastian LU (2020) In Fuel 263.
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... (More)

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.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Energy losses, Engine efficiency, Fuel properties, Molar expansion ratio, Spark-ignition engines
in
Fuel
volume
263
article number
116743
publisher
Elsevier
external identifiers
  • scopus:85076619055
ISSN
0016-2361
DOI
10.1016/j.fuel.2019.116743
language
English
LU publication?
yes
id
264fe17e-475e-447e-b4f2-e29d250f0213
date added to LUP
2020-01-02 13:16:41
date last changed
2020-01-08 08:58:12
@article{264fe17e-475e-447e-b4f2-e29d250f0213,
  abstract     = {<p>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.</p>},
  author       = {Nguyen, Duc Khanh and Szybist, James and Sileghem, Louis and Verhelst, Sebastian},
  issn         = {0016-2361},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Fuel},
  title        = {Effects of molar expansion ratio of fuels on engine efficiency},
  url          = {http://dx.doi.org/10.1016/j.fuel.2019.116743},
  doi          = {10.1016/j.fuel.2019.116743},
  volume       = {263},
  year         = {2020},
}