Abstract:

Particle mass (PM) emissions and particle number (PN) emissions per km were measured for 55 light-duty vehicles in China to quantitatively evaluate the particle emissions for domestic light-duty vehicles. Some diesel, gasoline direct injection (GDI) and multi-point injection (MPI) gasoline vehicles were tested on a chassis dynamometer according to the driving cycles by using the methods of laser condensation particle counting and filter paper weighing. The results show that the particle emissions of gasoline vehicles are significantly lower than those of stage 4 diesel vehicles. The PM average emission of gasoline vehicles is 6% of those of stage 4 diesel vehicles, and PN average emission of gasoline vehicles is 5% of those. The PN emissions of MPI vehicles are lower by one magnitude than those of GDI vehicles. The PN emissions of MPI and diesel vehicles increase largely due to the high-speed and long-acceleration working conditions of Worldwide Harmonized Light Vehicles Test Cycle (WLTC). The PN emission peak of GDI vehicles in the coldstart stage lasts a longer time compared with MPI and diesel vehicles. Other emission peaks occur obviously in the subsequent acceleration dynamic working conditions.

Key words:  light-duty vehicle, emissions, particle mass (PM), particle number (PN), chassis dynamometer test