K-1926 Effect of Injection Rate and Fuel Property on the Combustion Characteristics in a Direct-Injection Gasoline Engine

Abstract

This paper presents a study on the effect of injection rate on the performance and emissions in a direct injection gasoline engine. Five kinds of swirl injectors were utilized; their static injection rates were 600, 700, 800, 900 and 1000cc/min at the injection pressure of 7MPa. The BSFC is shown to have its optimum at lower rate of dynamic injection rate 10.7×10^<-2>cm^3/ms which is attributable to the combustion efficiency variation due to the behavior of droplet concentration. Two other factors of mechanical efficiency and cycle efficiency determining the thermal efficiency are discussed in comparison with the results of port injection operation.