An Investigation On Combustion Characteristics Of Direct Injection Diesel Engine Fuelled With Biodiesel

The shortage of energy sources and the worsen of environment are two important and serious problems that mankind is confronted with. Internal-combustion engine, as the main power-supply device of automobile, is not only a huge-energy-consuming device, but also a huge-pollutant-letting device. So recent years, the "clean alternative fuels" of engine have been receiving increasing attention. And biodiesel, because it is non-toxic, biodegradable and renewable, is becoming an important member of them.This paper has investigated the combustion characteristics of direct injection diesel engine fuelled with biodiesel and its effect to engine's performance and its pollutant emissions.At the beginning, it introduced the development of biodiesel and analyzed the environmental and economic benefits of developing it. And then, combining with experiment, the chemical theory and the detailed process of producing biodiesel in laboratory was presented.Then by comparative experiment on YZ4102QF diesel engine, the comparison of engine's performance and pollutant emissions of using diesel, B20 and B100 under 5 different loads at 3200r/min and 2200r/min have been gained. Then using computer program, the fuels' heat release rates and combustion characteristic parameters have been computed. Based on them, combustion characteristics of biodiesel and their reasons and effects have been researched. The main conclusions are: 1.The combustion characteristics: the shorter ignition delay and the earlier ignition, the decline of the peak value of heat release rate and the advance of its taking place, the decrease of diffusive combustion speed and the prolonging of combustion duration; 2. Its effect to engine's performance and emissions: the fuel consumption increases, the exhaust temperature decreases, the emissions of PT, CO and HC decrease greatly with nearly no increase of NO_x.At last, the effect of delaying its fuel delivery advance angles when using biodiesel has been investigated. By comparing the heat release rates and combustion characteristic parameters with different fuel delivery advance angles, the optimum value of this engine fueled with biodiesel has been educed.