An Analysis of the Impact of Selected Fuel Thermochemical Properties on Internal Combustion Engine Efficiency
- ORNL
- Oak Ridge National Laboratory (ORNL)
In this study we model the effects of 23 different fuels on First and Second Law thermodynamic efficiency of an adiabatic internal combustion engine. First Law efficiency is calculated using lower heating value (LHV) while Second Law efficiency is calculated with exergy, which represents the inherent chemical energy available to produce propulsion. We find that First Law efficiency can deviate by as much as nine percentage points between fuels while Second Law efficiency exhibits a much smaller degree of variability. We also find that First and Second Law efficiency can be nearly the same for some fuels (methane and ethane) but differ substantially for other fuels (hydrogen and ethanol). The differences in First and Second Law efficiency are due to differences in LHV and exergy for a given fuel. In order to explain First Law efficiency differences between fuels as well as the differences between LHV and exergy, we introduce a new term: the molar expansion ratio (MER), defined as the ratio of product moles to reactant moles for complete stoichiometric combustion. We find that the MER is a useful expression for providing a physical explanation for fuel-specific efficiency differences as well as differences between First and Second Law efficiency. First and Second Law efficiency are affected by a number of other fuel-specific thermochemical properties, such as the ratio of specific heat and dissociation of combustion products.
- 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)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1043931
- Journal Information:
- Energy & Fuels, Vol. 26, Issue 5; ISSN 0887-0624
- Country of Publication:
- United States
- Language:
- English
Similar Records
A Study of the Theoretical Potential of Thermochemical Exhaust Heat Recuperation in Internal Combustion Engines
Exergy and Economic Analysis of Catalytic Coal Gasifiers Coupled With Solid Oxide Fuel Cells