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Title: An assessment of thermodynamic merits for current and potential future engine operating strategies

Journal Article · · International Journal of Engine Research
 [1];  [2];  [2];  [2];  [2];  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuels, Engines and Emissions Research Center
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
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The present work compares the fundamental thermodynamic underpinnings (i.e., working fluid properties and heat release profile) of various combustion strategies with engine measurements. The approach employs a model that separately tracks the impacts on efficiency due to differences in rate of heat addition, volume change, mass addition, and molecular weight change for a given combination of working fluid, heat release profile, and engine geometry. Comparative analysis between measured and modeled efficiencies illustrates fundamental sources of efficiency reductions or opportunities inherent to various combustion regimes. Engine operating regimes chosen for analysis include stoichiometric spark-ignited combustion and lean compression-ignited combustion including HCCI, SA-HCCI, RCCI, GCI, and CDC. Within each combustion regime, effects such as engine load, combustion duration, combustion phasing, combustion chamber geometry, fuel properties, and charge dilution are explored. Model findings illustrate that even in the absence of losses such as heat transfer or incomplete combustion, the maximum possible thermal efficiency inherent to each operating strategy varies to a significant degree. Additionally, the experimentally measured losses are observed to be unique within a given operating strategy. The findings highlight the fact that in order to create a roadmap for future directions in ICE technologies, it is important to not only compare the absolute real-world efficiency of a given combustion strategy, but to also examine the measured efficiency in context of what is thermodynamically possible with the working fluid and boundary conditions prescribed by a strategy.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuels, Engines and Emissions Research Center (FEERC); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Transportation Research Center (NTRC)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1345788
Journal Information:
International Journal of Engine Research, Vol. 18, Issue 1-2; ISSN 1468-0874
Publisher:
SAGECopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 14 works
Citation information provided by
Web of Science

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Cited By (2)

Characterization of temporal variations and feedback timescales of exhaust gas recirculation gas properties using high-speed diode laser absorption spectroscopy for next-cycle control of cyclic variability journal August 2018
Improving the controllability of partial fuel stratification at low boost levels by applying a double late injection strategy journal January 2020

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33 ADVANCED PROPULSION SYSTEMS
42 ENGINEERING
Thermodynamics
Otto cycle
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efficiency
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