A biodiesel fuel, obtained from Jatropha seed in China, was tested in a direct injection, high pressure common-rail diesel engine for passenger cars. Effects of biodiesel on particle number and size distribution of the diesel engine are studied using an Engine Exhaust Particle Sizer (EEPS). Base petroleum diesel fuel, 10% and 20% v/v biodiesel blends with the base petroleum diesel fuel, the biodiesel fuel (B0, B10, B20 and B100 fuels) were tested without engine modification.
For all test fuels, the particle number and size distribution show unimodal or bimodal log-normal distribution, with a nucleation mode peak value in 6.04nm to 10.8nm particle diameter, and with an accumulation mode peak value in 39.2nm to 60.4nm particle diameter.
With the biodiesel blend ratios increasing, the number of nucleation mode particles increases and the particle size at peak value also gets larger, and the number of accumulation mode particles decreases and the particle size at peak value gets smaller, and the total particle number ascend at most engine operating conditions. Nucleation mode particles dominates the total particle number, and accumulation mode particles shows more effects at lower engine load with lower blend ratios of biodiesel fuel. With engine load increasing, the total particle number has small change using the biodiesel blend ratios less than 10% v/v, and has continuous ascend using the biodiesel blend ratios more than 20% v/v.