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Title: Catalytic EGR-Loop Reforming for High Efficiency in a Stoichiometric SI Engine through TCR and Dilution Limit Extension. 1. Catalyst Performance and Fuel Effects

Abstract

The use of fuel reformate from catalytic processes is known to have beneficial effects on the spark-ignited (SI) combustion process through enhanced dilution tolerance and decreased combustion duration, but in many cases reformate generation can incur a significant fuel penalty. Here, in this two-part investigation, we demonstrate that efficient catalytic fuel reforming can result in improved brake engine efficiency while maintaining stoichiometric exhaust under the right conditions. In part one of this investigation, we used a combination of thermodynamic equilibrium calculations and experimental fuel catalytic reforming measurements on an engine to characterize the best possible reforming performance and energetics over a range of equivalence ratios and O 2 concentrations. Ideally, one might expect the highest levels of thermochemical recuperation for the highest catalyst equivalence ratios. However, reforming under these conditions is highly endothermic, and the available enthalpy for reforming is constrained. Thus for relatively high equivalence ratios, more methane and less H 2 and CO are produced. Our experiments revealed that this suppression of H 2 and CO could be countered by adding small amounts of O 2, yielding as much as 15 vol % H 2 at the catalyst outlet for 4 < Φ catalyst < 7 under quasi-steady-statemore » conditions. Under these conditions the H 2 and CO yields were highest and there was significant water consumption, confirming the presence of steam reforming reactions. Analyses of the experimental catalyst measurements indicated the possibility of both endothermic and exothermic reaction stages and global reaction rates sufficient to enable the utilization of higher space velocities than those employed in our experiments. Finally, in a companion paper detailing part two of this investigation, we present results for the engine dilution tolerance and brake engine efficiency impacts of the reforming levels achieved.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuels, Engines, and Emissions Research Center
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
OSTI Identifier:
1417235
Alternate Identifier(s):
OSTI ID: 1415204
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Published Article
Journal Name:
Energy and Fuels
Additional Journal Information:
Journal Volume: 32; Journal Issue: 2; Journal ID: ISSN 0887-0624
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 08 HYDROGEN; Reforming; EGR; hydrogen; thermochemical recuperation

Citation Formats

Chang, Yan, Szybist, James P., Pihl, Josh A., and Brookshear, Daniel William. Catalytic EGR-Loop Reforming for High Efficiency in a Stoichiometric SI Engine through TCR and Dilution Limit Extension. 1. Catalyst Performance and Fuel Effects. United States: N. p., 2017. Web. doi:10.1021/acs.energyfuels.7b02564.
Chang, Yan, Szybist, James P., Pihl, Josh A., & Brookshear, Daniel William. Catalytic EGR-Loop Reforming for High Efficiency in a Stoichiometric SI Engine through TCR and Dilution Limit Extension. 1. Catalyst Performance and Fuel Effects. United States. doi:10.1021/acs.energyfuels.7b02564.
Chang, Yan, Szybist, James P., Pihl, Josh A., and Brookshear, Daniel William. Tue . "Catalytic EGR-Loop Reforming for High Efficiency in a Stoichiometric SI Engine through TCR and Dilution Limit Extension. 1. Catalyst Performance and Fuel Effects". United States. doi:10.1021/acs.energyfuels.7b02564.
@article{osti_1417235,
title = {Catalytic EGR-Loop Reforming for High Efficiency in a Stoichiometric SI Engine through TCR and Dilution Limit Extension. 1. Catalyst Performance and Fuel Effects},
author = {Chang, Yan and Szybist, James P. and Pihl, Josh A. and Brookshear, Daniel William},
abstractNote = {The use of fuel reformate from catalytic processes is known to have beneficial effects on the spark-ignited (SI) combustion process through enhanced dilution tolerance and decreased combustion duration, but in many cases reformate generation can incur a significant fuel penalty. Here, in this two-part investigation, we demonstrate that efficient catalytic fuel reforming can result in improved brake engine efficiency while maintaining stoichiometric exhaust under the right conditions. In part one of this investigation, we used a combination of thermodynamic equilibrium calculations and experimental fuel catalytic reforming measurements on an engine to characterize the best possible reforming performance and energetics over a range of equivalence ratios and O2 concentrations. Ideally, one might expect the highest levels of thermochemical recuperation for the highest catalyst equivalence ratios. However, reforming under these conditions is highly endothermic, and the available enthalpy for reforming is constrained. Thus for relatively high equivalence ratios, more methane and less H2 and CO are produced. Our experiments revealed that this suppression of H2 and CO could be countered by adding small amounts of O2, yielding as much as 15 vol % H2 at the catalyst outlet for 4 < Φcatalyst < 7 under quasi-steady-state conditions. Under these conditions the H2 and CO yields were highest and there was significant water consumption, confirming the presence of steam reforming reactions. Analyses of the experimental catalyst measurements indicated the possibility of both endothermic and exothermic reaction stages and global reaction rates sufficient to enable the utilization of higher space velocities than those employed in our experiments. Finally, in a companion paper detailing part two of this investigation, we present results for the engine dilution tolerance and brake engine efficiency impacts of the reforming levels achieved.},
doi = {10.1021/acs.energyfuels.7b02564},
journal = {Energy and Fuels},
number = 2,
volume = 32,
place = {United States},
year = {Tue Dec 19 00:00:00 EST 2017},
month = {Tue Dec 19 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1021/acs.energyfuels.7b02564

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Cited by: 2 works
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