Numerical Simulation Research of NOx Emissions Characteristic of Vehicle Engine Fueled with LPG

NO_x emissions characteristic of vehicle engine fueled with LPG (liquid petrol gas) was studied. A numerical simulation model was established by GT-POWER and was validated by experimental data. Based on the model, the variable parameters study including air-fuel radio, compression radio and ignition advance angle were carried out. The model results showed that the compression radio and the air-fuel radio played an important role during the NO_x emissions characteristic. There is a significant improvement of the NO_x emissions with the compression ratio increases. The cylinder pressure and temperature increased with the improvement of the compression ratio brought out the NO_x emissions rise. With the improvement of the air-fuel ratio, NO_x emissions increased first and then decreased. A larger ignition advance angle can decrease the NO_x emissions, at the same time the danger of knock corresponding increased. So the ignition advance angle must be appropriate selected.