国Ⅳ汽油出租车的冷、热启动污染物排放特征

Emission characteristics of gasoline taxi cabs complying with China Ⅳ emission standards during cold and hot starts

为研究冷、热启动对中国轻型汽油车排放的影响,利用便携式排放测试系统(PEMS),对3辆国Ⅳ汽油出租车的尾气排放开展了实际道路测试。研究发现:冷启动和热启动对车辆排放的影响分别在启动300s和120s后基本结束。车辆在不同状态下启动时的HC和CO排放差异很大,启动前发动机熄火的时间越短,启动时的HC和CO排放越低。冷启动阶段的HC和CO排放分别达到3.3g和21.9g,约是第1次热启动的10倍和6倍,约是第2次热启动和31倍和12倍。但NOx排放受此影响较小,而受驾驶习惯的影响更大。

Cold and hot start emissions play a more and more important role in light-duty vehicles in China. Three gasoline taxi cabs were chosen, which comply with China IV emission standards, for emission testing on the real road using a portable emission measurement system （PEMS）. The results show that cold start almost ended its impact on vehicle emissions after 300 s and hot start almost ended after 120 s according to the emission data. There are significant differences in HC and CO emissions under different kinds of vehicle starts conditions. The shorter the interval between engine stop and start, the less HC and CO emissions right after the starts. During the cold start, HC and CO emissions were 3.3 g and 21.9 g, which are 10 and 6 times of those in the first hot start, and 31 and 12 times of those in the sencond hot start, respectively. The influence of start conditions is not so significant on NOx emission, which is affected more by driving behavior.