An experimental study of the effects of combustion systems and fuel properties on the performance of a diesel engine

Abstract

This paper investigates the effects of combustion system and fuel properties on spray, mixture formation, combustion process, and emissions, using a constant volume chamber and single- cylinder engine. In a combustion system, high-pressure injection, exhaust gas recirculation (EGR), and impingement spray are applied while visualizing and analysing exhaust gas. Also, light diesel fuel, which has approximately the same cetane value as the diesel but has low values of PAHs, boiling point, density, viscosity, and surface tension, were used. Spray and combustion images were taken using a high-speed video camera and analysed by their penetration and evaporation characteristics in comparison with current diesel fuel. The results showed that the mixture formation of the high- pressure injection, impingement spray, and light diesel fuel is faster than that of diesel fuel, depending on physical properties. In the engine test, a considerable reduction of smoke emission was observed using the high-pressure injection with supercharging, due to the enhanced fuel atomization and air entrainment. In addition, a high reduction of NOx emission can be achieved with a high EGR rate, and with supercharging can achieve a reduction of NOx emission without deteriorating BSFC.