Combustion losses in automotive spark ignition and diesel engines. [VEHSIM computer code]

Technical Report · Sun Aug 01 00:00:00 EDT 1982

OSTI ID:6500190

Mascetti, G J; Roessler, W U

This report quantifies the magnitude of combustion losses occurring in automotive engines due to both incomplete and slow combustion of the air-fuel mixture. The magnitude of these losses serves to define the maximum fuel economy improvement potentially available through use of fuel additives and/or engine modifications intended to improve the combustion process. Incomplete combustion is characterized by the presence of unreacted fuel-derived species in the exhaust. Concentrations of these species are measured on the engine dynamometer for eight spark ignition engines and three diesel engines, and are used to calculate combustion losses. A computer simulation of vehicle operation (VEHSIM Program) is then used to determine losses over the EPA Urban Driving Cycle, which typifies normal driving patterns. Slow combustion converts chemical energy to thermal energy over a range of piston positions, rather than at top dead center. A loss in available work occurs because expansion then takes place for less than the full piston stroke. These losses are evaluated analytically by utilizing ideal thermal efficiency calculations for each increment of the air-fuel charge and the effective compression ratio at which its combustion occurs. The thermal efficiencies for these increments are then integrated to obtain the average value for combustion of the entire charge.

• Research Organization: Aerospace Corp., El Segundo, CA (USA)
• DOE Contract Number: AI01-82CS50286
• OSTI ID: 6500190
• Report Number(s): DOE/CS/50286-2; ON: DE83006015
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
AUTOMOTIVE FUELS
COMBUSTION
DIESEL ENGINES
ENERGY LOSSES
THERMAL EFFICIENCY
SPARK IGNITION ENGINES
AUTOMOBILES
COMBUSTION PROPERTIES
FUEL-AIR RATIO
V CODES
CHEMICAL REACTIONS
COMPUTER CODES
EFFICIENCY
ENGINES
FUELS
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
LOSSES
OXIDATION
THERMOCHEMICAL PROCESSES
VEHICLES
330101* - Internal Combustion Engines- Spark-Ignition
330102 - Internal Combustion Engines- Diesel