TY - JOUR
T1 - New insights into fuel blending effects: Intermolecular chemical kinetic interactions affecting autoignition times and intermediate-temperature heat release
AU - Cheng, Song
AU - Scott Goldsborough, S.
AU - Saggese, Chiara
AU - Wagnon, Scott W.
AU - Pitz, William J.
N1 - Funding Information:
This manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory, a U.S. Department of Energy Office of Science laboratory, under Contract No. DE-AC02?06CH11357. The work at LLNL was performed under the auspices of the U.S. Department of Energy (DOE), Contract DE-AC52?07NA27344. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The DOE will provide public access in accordance with http://energy.gov/downloads/doe-public-access-plan. This research was conducted as part of the Partnership to Advance Combustion Engines (PACE) sponsored by the U.S. Department of Energy (DOE) Vehicle Technologies Office (VTO), and the Co-Optimization of Fuels and Engines (Co-Optima) initiative sponsored by the U.S. DOE Office of Energy Efficiency and Renewable Energy and Bioenergy Technologies, and VTO. Co-Optima is a collaborative project of multiple national laboratories initiated to simultaneously accelerate the introduction of affordable, scalable, and sustainable biofuels and high-efficiency, low-emission vehicle engines. Special thanks to program managers Kevin Stork, Gurpreet Singh, and Mike Weismiller. The authors acknowledge Dr. Goutham Kukkadapu at LLNL for his suggestions to improve the paper.
Funding Information:
This manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory, a U.S. Department of Energy Office of Science laboratory, under Contract No. DE-AC02–06CH11357. The work at LLNL was performed under the auspices of the U.S. Department of Energy (DOE), Contract DE-AC52–07NA27344. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The DOE will provide public access in accordance with http://energy.gov/downloads/doe-public-access-plan .
Funding Information:
This research was conducted as part of the Partnership to Advance Combustion Engines (PACE) sponsored by the U.S. Department of Energy (DOE) Vehicle Technologies Office (VTO), and the Co-Optimization of Fuels and Engines (Co-Optima) initiative sponsored by the U.S. DOE Office of Energy Efficiency and Renewable Energy and Bioenergy Technologies, and VTO. Co-Optima is a collaborative project of multiple national laboratories initiated to simultaneously accelerate the introduction of affordable, scalable, and sustainable biofuels and high-efficiency, low-emission vehicle engines. Special thanks to program managers Kevin Stork, Gurpreet Singh, and Mike Weismiller.
Publisher Copyright:
© 2021
PY - 2021/11
Y1 - 2021/11
N2 - Fuel blending effects on chemically-dominated fuel properties, such as gasoline anti-knock quality, are influenced by fundamental chemical kinetic interactions between the blending agent and the base fuel. Historically, quantification of such interactions has focused on direct changes to the radical pool, including ȮH and HO2, while intermolecular chemical kinetic interactions pertaining to carbon-containing, non-fuel-specific intermediates are typically overlooked. In this regard, this work aims to derive new insight into intermolecular chemical kinetic interactions that are intrinsic to fuel blending effects, via a case study on blends of 0–30% ethanol (by volume) into FGF-LLNL (a multi-component gasoline surrogate for FACE-F research gasoline) using a rapid compression machine at a diluted/stoichiometric fuel loading, compressed pressure of 40 bar and low- to intermediate-temperature regimes that are representative of boosted SI engine operation. Ethanol blending effects on the intermediate temperature heat release (ITHR) of FGF-LLNL are characterized using experimental measurements, where ethanol is found to promote the extent of ITHR and suppress the transition from ITHR to main ignition. Chemical kinetic modeling is undertaken using recently updated gasoline surrogate and alcohol models. Sensitivity analyses on ITHR characteristics further corroborate the ethanol blending effects, and highlight the significant dependence of ITHR on both fuel-specific and non-fuel-specific reactions. An approach allowing comprehensive characterization of the complex intermolecular chemical kinetic interactions between constituents in a fuel blend is then proposed. Application of the approach to FGF-LLNL/E0–E30 reveals that ethanol perturbs the heat release and autoignition characteristics of FGF-LLNL not only by directly changing the ȮH and HO2 radical pools via fuel-specific reactions, but also indirectly through intermolecular interactions where participating intermediates can be produced and consumed by various sub-chemistries. Disabling the intermolecular interactions in carbon-containing species between ethanol and FGF-LLNL sub-chemistries leads to somewhat slower ITHR evolution and lower ignition reactivity. The role of the individual intermolecular interaction is also characterized using the proposed approach. Finally, implications of intermolecular interactions for future studies that aim to improve model performance are highlighted, where it is found that further investigations on the acetaldehyde sub-model and FGF-LLNL/ethanol interactive chemical reactions (e.g., FGF-LLNL+CH3O2 and RO2+ethanol) are needed for chemistry models to accurately predict fuel blending behavior.
AB - Fuel blending effects on chemically-dominated fuel properties, such as gasoline anti-knock quality, are influenced by fundamental chemical kinetic interactions between the blending agent and the base fuel. Historically, quantification of such interactions has focused on direct changes to the radical pool, including ȮH and HO2, while intermolecular chemical kinetic interactions pertaining to carbon-containing, non-fuel-specific intermediates are typically overlooked. In this regard, this work aims to derive new insight into intermolecular chemical kinetic interactions that are intrinsic to fuel blending effects, via a case study on blends of 0–30% ethanol (by volume) into FGF-LLNL (a multi-component gasoline surrogate for FACE-F research gasoline) using a rapid compression machine at a diluted/stoichiometric fuel loading, compressed pressure of 40 bar and low- to intermediate-temperature regimes that are representative of boosted SI engine operation. Ethanol blending effects on the intermediate temperature heat release (ITHR) of FGF-LLNL are characterized using experimental measurements, where ethanol is found to promote the extent of ITHR and suppress the transition from ITHR to main ignition. Chemical kinetic modeling is undertaken using recently updated gasoline surrogate and alcohol models. Sensitivity analyses on ITHR characteristics further corroborate the ethanol blending effects, and highlight the significant dependence of ITHR on both fuel-specific and non-fuel-specific reactions. An approach allowing comprehensive characterization of the complex intermolecular chemical kinetic interactions between constituents in a fuel blend is then proposed. Application of the approach to FGF-LLNL/E0–E30 reveals that ethanol perturbs the heat release and autoignition characteristics of FGF-LLNL not only by directly changing the ȮH and HO2 radical pools via fuel-specific reactions, but also indirectly through intermolecular interactions where participating intermediates can be produced and consumed by various sub-chemistries. Disabling the intermolecular interactions in carbon-containing species between ethanol and FGF-LLNL sub-chemistries leads to somewhat slower ITHR evolution and lower ignition reactivity. The role of the individual intermolecular interaction is also characterized using the proposed approach. Finally, implications of intermolecular interactions for future studies that aim to improve model performance are highlighted, where it is found that further investigations on the acetaldehyde sub-model and FGF-LLNL/ethanol interactive chemical reactions (e.g., FGF-LLNL+CH3O2 and RO2+ethanol) are needed for chemistry models to accurately predict fuel blending behavior.
KW - Autoignition
KW - Fuel blending effects
KW - Intermediate temperature heat release
KW - Intermolecular chemical kinetic interactions
KW - Simulated molecular tagging
UR - http://www.scopus.com/inward/record.url?scp=85108986035&partnerID=8YFLogxK
U2 - 10.1016/j.combustflame.2021.111559
DO - 10.1016/j.combustflame.2021.111559
M3 - Journal article
AN - SCOPUS:85108986035
SN - 0010-2180
VL - 233
JO - Combustion and Flame
JF - Combustion and Flame
M1 - 111559
ER -