Performance And Emission Characteristics Of Diesel Engine Fueled With Biodiesel-Ethanol Blends

Environmental pollution and energy source shortage are two main factors that restrict the development of diesel engine industry. Developing "clean alternative fuels" has become a trend to release this problem. Ethanol and biodiesel have been the hot spot because of their environment friendly and renewability.This paper is mainly concerned about the solubility of different biodiesel -ethanol blends , their performing on the diesel engine and the influences on the emission characteristics and the combustion characteristics of the diesel engine fueled with biodiesel and biodiesel - ethanol blends(BEF).The result shows that after using the BEF on the diesel engine, it can well reach the original engine power, and the equivalent brake specific fuel consumption rate have been improved to some extent when the proportion of ethanol in BEF is below 30%. Compared with conventional diesel fuel, BEF show sharply reduction in carbon monoxide (CO) at high load condition and with the increasing proportion of ethanol it shows slightly higher HC emissions but slightly improvement in NOx emissions. And it shows apparently lower smoke emissions at all conditions. When the diesel engine is fueled with E30(the proportion of ethanol is 30%), CO NOx and smoke emissions get the maximum reduction by 80% 20% and 86% respectively, while HC emissions get the maximum increase by 67.6% at rated condition. It also shows that there is an optimal fuel supply advance angle and an optimal value of fuel injection pressure to improve the total performance of the diesel fueled with ethanol-biodiesel blends.As for the combustion characteristics, with the decrease of the engine load ,it gets a reduction in the in-cylinder pressure, the average rising rate of pressure, heat release and in-cylinder temperature and results in longer ignition delay period and shorter combustion duration when fueled with the same blends. With the increase of ethanol proportion, the period of ignition delay becomes longer, the maximum of heat release rate is increased and its appearance is delayed, the combustion duration becomes shorter, both the maximum ofin-cylinder pressure and the maximum of pressure rise are increased.In summary, biodiesel - ethanol blends showed great advantages on the diesel engine. Thus promoting ethanol-biodiesel blends on the diesel engine is practical.