Combustion And Emission Characteristics Of CI Engine Fueled With Different Biodiesel

With the rapid development of the global economy, the oil shortage and environmental pollution is getting worse. In terms of vehicle engines, to find and use efficient, clean and renewable alternative fuel is effective measures to mitigate this double pressure. Due to the similar physical and chemical properties with diesel fuel and excellent combustion characteristics, biodiesel has become a hot research on alternative fuel at home and abroad in recent years. Research on the impact of biodiesel on vehicle engine combustion and emission has a great significance for its application and promotion.As a new alternative fuel, to obtain biodiesel fuel physical parameters is particularly important when the engine working process is simulated. This paper has estimated physical parameters such as enthalpy, latent heat of vaporization, vapor pressure, surface tension, liquid viscosity and thermal conductivity of biodiesel with Fortran programming language.In this paper, numerical simulation are performed in KIVA-3V to investigate the effect of three kinds of biodiesel (soybean oil methyl ester, palm oil methyl ester and Jatropha oil methyl ester) on the characteristics of combustion and emission in a compression-ignition engine, compared with that of diesel fuel respectively. The results showed that:the overall average cylinder temperature of the biodiesel is lower than that of diesel, and after the peak of temperature, the average cylinder temperature of the three biodiesels reduces with the order of low calorie. In the case of same amount of fuel injection, the mean effective pressure of biodiesel is about10percent lower than diesel. In terms of exhaust, the soot, CO and NOx emissions of biodiesel are lower than diesel.In addition, the combustion and emission laws of diesel and jatropha oil methyl ester under different injection timing are studied. The results showed that:Jatropha oil methyl ester and diesel have a consistent variation in cylinder temperature and pressure at same injection time. With the delayed injection, the cylinder temperature gap between Jatropha oil methyl ester and diesel decreases. In terms of emissions, the formation of soot and NOx of the two fuels change consistently with the crank angle at same injection time. With the postponement of injection, the difference of soot final emissions between the two fuels increase, but the NOx emission decrease.