汽油車顆粒物排放特性

在底盤測功機上按NEDC循環工況,使用輕型汽油車、輕型柴油車排放測試系統以及電子低壓沖擊儀(ELPI)對滿足國Ⅲ、國Ⅳ的氣道噴射和缸內直噴汽油車進行了冷起動和熱起動條件下的顆粒物排放特性研究。結果表明:國Ⅲ汽油車冷起動排出的顆粒物數目和粒徑比其他汽油車都高,而國Ⅳ直噴汽油車排出的顆粒物的表面積濃度和質量濃度最大。各種汽油車排放的粒子數濃度的數量級相同,均為106,熱起動下的顆粒物排放比冷起動減少40%。汽油車的粒徑濃度90%以上都分布在0.007～0.378μm,表面積濃度90%以上都分布在0.055～9.83μm,顆粒物質量濃度99%分布在0.091～9.83μm。ELPI計算和顆粒測試系統測量的結果都證明,氣道噴射汽油車在EUDC循環下顆粒物質量排放比ECE循環高。試驗結果也發現,ELPI計算的顆粒物質量與法規測試系統測量的顆粒物質量之間存在差異。

Characteristics of particulate emissions from gasoline vehicles

The characteristics of particulate emissions from gasoline vehicles complying to Euro 3 or Euro 4 emission standards with port fuel injection ( PFI) engine or gasoline direct injection ( GDI) engine were investigated under cold start and hot start conditions by means of an electrical low-pressure impactor( ELPI) and an exhaust emission measuring system for the light-duty vehicle on a chassis dynamometer. The results show that the particulates emission from a Euro 3 PFI gasoline vehicle at cold start is characterized by higher particle number concentration and larger particle size,and that from a Euro 4 GDI vehicle is characterized by the highest particle area and mass concentrations. The particle number concentrations exhausted from both vehicles are in the same magnitude order of 106,and the particulates emission at hot start condition is 40% lower than that at cold start condition. More than 90% of the particle size concentration is distributed in the size range of 0. 007 ～ 0. 378 μm,more than 90% of the particle area concentration in the range of 0. 055 ～ 9. 83 μm,and 99% of the particle mass concentration in the range of 0. 091 ～ 9. 83 μm. Both the results calculated by ELPI and measured by particulate measuring system show that the particulates mass emissions from PFI gasoline vehicle under EUDC driving cycle are higher than those under ECE driving cycle. Results also show the particulates mass calculated by ELPI is different from that measured by standard measuring system.