Experimental investigation of combustion characteristics of ethanol-gasoline blended fuel in a T-GDI engine

Abstract

Interest in reducing greenhouse-gas emissions has increased in past decades because of global warming. In particular, research on alternative fuels for internal combustion engines is in progress for eliminating dependence on existing fossil fuels. Bioethanol-an alternative fuel-has attracted attention because it can be applied without major modifications to conventional internal combustion engines that use fossil fuels. However, further research is necessary, because gasoline and ethanol have different spray and combustion characteristics owing to differences in their physical properties. In this study, the penetration length, spray angle, and spray pattern were analyzed through spray experiments in which the blend ratio of ethanol-gasoline blended fuel was varied. In addition, a direct injection-type flex fuel vehicle engine test device was built, and the combustion and knocking characteristics were investigated with respect to the ethanol ratio through an engine test. Compared with the brake-specific fuel consumption and the combustion pressure of E0, those of E100 increased by 28.7% (because the lower heating value was lower for E100) and reduced by 11.2%, respectively. The heat-release rate of E22 increased faster than that of E0 owing to the characteristics of ethanol, which is an oxygen-containing fuel, and the high vaporization rate. The anti-knock properties of ethanol were superior to those of gasoline; therefore, knocking hardly occurred for fuel blend ratios above E50.