缸内直喷汽油机排放颗粒有机物特征及影响因素分析

Characteristics of Particulate Organic Matters Emissions From Gasoline Direct Injection Engine and Its Influence Factors

机动车排放颗粒物是我国城市大气PM_（2.5）重要来源。缸内直喷（gasoline direct injection,GDI）汽油机具有油耗低、CO2排放低等优点,将成为未来汽油车发展方向。然而GDI汽油机颗粒物排放高,造成的环境影响值得关注。有机物（organic matters,OM）是大气颗粒物的重要组分,有着重要的健康效应和气候效应。其中可以定量检测的部分颗粒有机物（particulate organic matters,POM）有着较好的源指示作用。通过台架实验研究了GDI汽油机排放PM_（2.5）中POM的组成、排放因子等的特征,以及转速、负荷、催化剂等因素对POM组成的影响,给出汽油机排放POM源谱。定量颗粒有机物的总质量分别可以占到总有机物OM和PM_（2.5）质量浓度的14%~56%和7%~44%。多环芳烃、正构烷烃、正构烷酸、芳香酸、二元羧酸是最主要的物种。POM排放因子随转速增加而增大,对于中、低转速,POM排放因子随着负荷的增加呈现出先降低后增加的趋势;在高转速时,POM排放因子随着负荷增加而增加。三效催化剂对颗粒有机物的排放的削减作用可达到19%~64%。我国汽油车排放POM源谱与国外源谱有差异。采集和测量我国实地源样品,得到符合我国实际情况的汽油车POM源谱,对于解析我国大气颗粒物来源中的汽油车贡献至关重要。

Vehicle emitted particulate matters is an important source for urban atmospheric PM_（2.5）. Gasoline direct injection（GDI） engines can reduce fuel consumption and CO2 emissions, and it would become more and more popular in the near future. The large amount of particle emission by GDI engine should take the public attention. Organic matter（OM） is one of the main components of atmospheric particulate matters, which has important health and climate effects. Particulate organic matter（POM）, the quantifiable part of OM, is good source indicators for source identification. The characteristics of POM component, emission factors and source profile were investigated from GDI engine, particularly focused on the effect of engine speed, load and the catalyst. Results show that POM recognized and quantified in this research account for 14%~56% of organic matters, and 7%~44% of total PM_（2.5） mass concentration. PAHs, n-alkanes, n-alkanoic acids, aromatic acids and dicarboxylic acids are the main components of POM. At low and median engine speed, with the increase of engine load, POM firstly decreases and then gradually increases,while it show an increasing trend with the increase of load in high engine speed. Three-way catalyst（TWC） decreases the POM emission by 19%~64%. The POM source profile of China differs a lot from foreign source profile. It＇s quite urgent to collect our own gasoline vehicle emitted samples and get the actual POM source profile in order to acquire the precise result of source apportionment.