环境温度对汽油缸内直喷汽车排放的影响

选取2辆典型汽油缸内直喷汽车(GDIV)，在环境舱内进行了不同环境温度下，车辆冷启动和热启动后按照全球轻型车统一测试循环(WLTC)运行时的排气污染物试验，测量并分析了GDIV排气中的气态污染物和颗粒物，旨在为GDIV排放系统设计、控制策略制定以及评价汽车排放对环境影响的相关研究提供理论依据。研究结果表明:环境温度对GDIV试验车辆冷启动和热启动的颗粒物数量(PN)和颗粒物质量(PM)排放因子影响显著。环境温度低于14℃，冷启动工况下行驶时PN排放难以满足国Ⅵ排放标准限值，总碳氢化合物(THC)和CO的排放因子受温度的影响显著，热启动时影响不明显。无论是热启动还是冷启动工况，当温度从-7℃逐步上升到40℃时，试验车辆的CO₂排放因子呈现先减少后增加的变化规律，2辆车在热启动时的CO₂排放因子比冷启动时平均降低4%和7%。冷启动和热启动时，氮氧化物(NO_x)排放因子受温度的影响均没有明显的规律。 

Impact of ambient temperature on GDIV emission

Two typical Gasoline Direct Injection Vehicles (GDIVs) were selected, and emission tests in the environmental cabin were performed under Worldwide harmonized Light-duty rehicles Test Cycle (WLTC) at different ambient temperatures after the vehicles cold-started and hot-started. The gaseous pollutants and particulates in GDIV emissions were measured and analyzed with the aim of providing a theoretical basis for the GDIV emission system design and control, as well as for related research to evaluate the impact of automobile emissions on the environment. The results show that ambient temperature has a significant effect on the Particle Number (PN) and Particle Matter (PM) emission factor of the tested vehicles. The PN emission factor under the cold start condition is difficult to meet the China 6 emission limit when ambient temperature is below 14℃. The emission factors of Total Hydrocarbons (THC) and CO are significantly affected by temperature under cold start condition but are not significantly affected under hot start condition. Regardless of the hot start or cold start conditions, when the temperature gradually rises from -7℃ to 40℃, the CO₂ emission factor of the test vehicle first decreases and then increases, and the CO₂ emission factor of the two vehicles during hot start is reduced by 4% and 7% on average compared to cold start. There is no obvious rule of Nitrogen Oxide (NO_x) emission factor influenced by temperature under cold start and hot start conditions.