Effects of Pre-spark Heat Release of Ethanol-Blended Gasoline
Surrogate Fuels on Engine Combustion Behavior 04-17-01-0003
This also appears in
SAE International Journal of Fuels and Lubricants-V133-4EJ
Regulations limiting greenhouse gas (GHG) emissions in the transport sector have
become more restrictive in recent years, drawing interest to synthetic fuels
such as e-fuels and biofuels that could “decarbonize” existing vehicles. This
study focuses on the potential to increase the thermal efficiency of
spark-ignition (SI) engines using ethanol as a renewable fuel, which requires a
deep understanding of the effects of ethanol on combustion behavior with high
compression ratios (CRs). An important phenomenon in this condition is pre-spark
heat release (PSHR), which occurs in engines with high CRs in boosted conditions
and changes the fuel reactivity, leading to changes in the burning velocity.
Fuel blends containing ethanol display high octane sensitivity (OS) and limited
low-temperature heat release (LTHR). Consequently, their burning velocities with
PSHR may differ from that of gasoline. This study therefore aimed to clarify the
effects of ethanol on SI combustion behavior under PSHR conditions. Combustion
behavior was studied by performing single-cylinder engine experiments and
chemical kinetics simulations. The experimental measurements were performed to
characterize the relationship between the occurrence of PSHR and the main
combustion duration. Analysis of this relationship showed that the
ethanol-blended fuel has a lesser PSHR and a longer combustion duration than the
non-ethanol fuel by approximately 5% in high engine load conditions. Simulations
using input data from the experiments revealed that the ethanol-blended fuel has
a lower laminar burning velocity due to the lower temperature in the unburned
mixture caused by its PSHR. Additional simulations examining the chemical effect
of partially oxidized reactants caused by PSHR on the laminar burning velocity
showed that partially oxidized reactants increase the laminar burning velocity
of the ethanol-blended fuel but decrease that of a reference fuel without
ethanol. A large number of fuel radicals and oxides of the ethanol-blended fuel
enhances chain-branching reactions in the pre-flame zone and possibly increases
its laminar burning velocity. However, the thermodynamic effect of PSHR on
laminar burning velocity exceeds the chemical effect, and thus the
ethanol-blended fuel has a lower turbulent burning velocity in the PSHR
conditions.
Citation: Yoshimura, K., Isobe, K., Kawashima, M., Yamaguchi, K. et al., "Effects of Pre-spark Heat Release of Ethanol-Blended Gasoline Surrogate Fuels on Engine Combustion Behavior," SAE Int. J. Fuels Lubr. 17(1):2024, https://doi.org/10.4271/04-17-01-0003. Download Citation
Affiliated:
Waseda University, Graduate School of Creative Science and Engineering,
Japan, Kokushikan University, School of Science and Engineering,
Mechanical Engineering, Japan, Waseda University, The Research Organization for Next Generation
Vehicles, Research Council, Japan, Suzuki Motor Corporation, Automobile Power Unit Design Department,
Japan, Waseda University, Graduate School of Creative Science and
Engineering, Japan
Pages: 14
ISSN:
1946-3952
e-ISSN:
1946-3960
Related Topics:
Synthetic fuels
Single cylinder engines
Spark ignition engines
Combustion and combustion processes
Ethanol
Greenhouse gas emissions
Engines
Gasoline
Biofuels
Octane
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