Abstract: An experiment investigation was carried out to study the effect of fuel volatility on particle matter emission in common-rail diesel engine, and analyze the characteristics of particle size distribution under different load conditions. The results show that refining the fuel volatility can increase the nuclear state fine particle number concentration in low and medium load condition, reduce the emission fine particle number and mass concentration in high load condition, but has little influence on the accumulative state fine particle number concentration. For different volatile fuels, the fine particle number concentration in nuclear state reaches the highest point at the equivalent ratio of 0.4 with the same fuel in different load conditions. In low and medium load condition, adding small amount of volatile fuel into the fuel with poor volatility will result in sharp increase in the nuclear state fine particle number concentration. With further improvement of the fuel volatility when the adding proportion increased, both nuclear state fine particle number concentration and the total fine particle number concentration decrease in low and medium load condition, but the accumulative state fine particle number concentration rarely changes. For high load condition, with fuel of medium volatility, boiling point of 263 °C, both the nuclear state fine particle number concentration and total fine particle number concentration are the highest. For fuel of better volatility with boiling point of 244 °C, both the nuclear state fine particle number concentration and total fine particle number concentration are the lowest.

Key words: power engineering, common-rail diesel engine, fuel volatility, particulate emission, particle size distribution