Combustion Efficiencies of Spark Ignition Engine. Estimation of Combustion Efficiencies from Concentration of Unburned Species in Exhaust and Residual Gases.

Abstract

In order to improve the fuel economy of internal combustion engines it is desirable to attain higher combustion efficiencies. Usually combustion efficiencies should be more than 90% in spark ignition engines. However they may depend on engine operating conditions and some engine design parameters. They were analyzed by a method of estimation of the concentration of unburned species in the exhaust and residual gases. The concentrations of burned and unburned species in the combustion chamber were measured at the time of the late exhaust process by the gas sampling technique. The unburned species-intake fuel ratio was calculated from the hydrocarbon and carbon monoxide masses in the residual and exhaust gases. They were estimated under several sets of operating conditions, equivalent ratio and ignition advance. The influence of compression ratios was also investigated. It was concluded that combustion efficiencies of a spark ignition engine could be estimated precisely by the gas sampling method.