芳香烃含量对直喷汽油机颗粒物排放影响的试验研究

在一台增压中冷缸内直喷(GDI)汽油机上,开展了不同芳香烃含量的汽油对发动机颗粒物粒径分布和数量浓度影响的研究.结果表明,在正常热机工况下,随着负荷增加,核态颗粒物增加明显,颗粒物排放逐渐由三峰分布演变为双峰分布,并且芳烃含量高时,颗粒物排放明显增多.冷机工况及冷怠速时,芳烃含量对颗粒物的排放影响较小.和冷怠速相比,热怠速时颗粒物向小粒径方向移动,且颗粒物数量减少.热怠速时高芳烃含量的汽油排气中颗粒物相对较多.不同芳烃含量下,发动机参数对颗粒物排放会有一定影响,重芳烃含量高的汽油其颗粒物排放也高.

Effect of aromatics on the particulate matter emission of a GDI engine

Particulate matter (PM) emissions from a turbocharged GDI gasoline engine operating on two kinds of fuels with different amount of aromatics were examined and compared. The results indicated that, under the normal operation condition, the proportion of number concentration of particles in nucleation mode increased and became dominant with increasing engine load, and their distribution curves were converted from trimodal to bimodal. The fuel with higher aromatics could lead to higher concentration of PM. As a contrast, the amounts of aromatics in gasoline had little effect on PM emission while the engine was operated at low temperature condition including cold starting and idling condition. Comparing with cold idling condition, warm idling condition led to lower amount of PM emissions with smaller size, but PMs were more concentrated from gasoline with high concentration of aromatics. When amounts of aromatics in gasoline are different, heavy aromatics played an important role in PM emission. Engine parameters of engine also had certain influence on PM emissions.