缸内直喷汽油车颗粒物化学组分特征

With the widespread use of direct-injection gasoline vehicles, their tailpipe particulate emissions are becoming a serious problem for the urban atmosphere. The study of tailpipe particulate components from direct-injection gasoline vehicles is an important preliminary work to control particulate emissions effectively. In this study, five direct-injection gasoline vehicles meeting the China-6 emission standard were tested to analyze the carbonaceous components, water-soluble ions, and polycyclic aromatic hydrocarbons of tailpipe particulate emissions. It was found that carbonaceous substances were the major components of exhaust particles, accounting for approximately 70%. More organic carbon than elemental carbon was found in the particulate emissions of direct-injection gasoline vehicles, with OC/ EC ratios of 1. 03 to 3. 43. The study also measured various water-soluble ions of particles. The total mass proportions of water-soluble ions were 11. 3% to 17. 6%. Ca^{2 +} and SO²₄^- were the main water-soluble ions, with oil additives being the main source of these two ions. In addition, it was found that the PAHs emissions were significantly reduced with stricter regulations. PAHs emission factors of GDI vehicles meeting the China-6 standard were reduced by more than half of the emission factors of China-6-standard GDI vehicles. Moreover, GDI vehicles had a high proportion of high-cyclic PAHs emissions in exhaust particles, which damages public health and requires more attention.