Abstract: In order to investigate the effect of ethanol addition on gasoline direct injection engine particulate emission during the starting period, E10 and E20 fuels are obtained by blending 10% and 20% volume fraction ethanol fuel into gasoline. With the two fuels and gasoline fuel, study of particulate emission from GDI engine during the starting period is conducted. It is found that particle number concentration increases dramatically during the first 10 seconds of the initial starting period with each fuel, which is due to increase of both nuclear mode and accumulated mode particles. The particulate emission is dominated by nuclear mode particles. As the temperature of the coolant increases, the amount of accumulated particles decreases dramatically. Adding a certain amount of ethanol to gasoline can improve the emission of nuclear mode particles under the start condition. The total concentration of particulates reduces by 37.8% and 64.5% during 40s starting period respectively, at 20 and 80℃ with E20 fuel.

Key words: gasoline direct injection engine, ethanol, particulate, start, emission