An experimental study on the performance and exhaust emissions of a diesel engine fuelled with soybean oil methyl ester

Abstract In order to optimize the application of biodiesel for diesel engines, the emissions, fuel economies, and power performances of diesel, soybean oil methyl ester, and its blends with diesel from 10 to 80wt% were compared and analysed by bench tests of a supercharged direct injection (DI) diesel engine. The exhaust emissions (smoke density, NO x , CO, and HC), the brake specific fuel consumption rate, the specific energy consumption rate, and the brake power and torque were investigated under different engine loads and speeds. Experimental results show that, compared with diesel fuel, with increase in the soybean oil methyl ester percentage in the blends, smoke density and HC decrease while NO x emissions increase, CO increases under full load at 2000r/min but decreases at 3000r/min, specific energy consumption decreases and brake specific fuel consumption increases under different loads at 2200r/min, and brake power and torque increase at different speeds under full load. A biodiesel content of 20wt% is an optimum compromise between increased NO x and reduction in smoke density.