基于PEMS车载排放测试系统，对一辆安装DOC+CDPF的重型柴油货运车进行了三次不同行驶里程下的道路排放跟踪测试。试验结果表明：从低速工况到高速工况，原车的CO、THC、PM排放因子呈下降趋势，而NO_x、PN则呈上升趋势。加装DOC+CDPF后，CO、THC、PM、PN减排率基本随车速的增大逐渐升高，而DOC+CDPF对NO_x排放影响不大。随着车辆行驶里程的增加，DOC+CDPF对CO、NO_x的减排性能逐渐减弱，减排率在第1次试验时有最大值，分别为59.8%，9.7%；DOC+CDPF对THC、PN、PM的减排性能则先增强后减弱，减排率在第2次试验时有最大值，分别为53.5%，99%，87.3%。

Based on the PEMS, three road tracking emission tests in different vehicle mileage were conducted on a heavy-duty diesel truck with DOC and CDPF. Test results showed that CO, THC and PM emission factors of original vehicle showed a downward trend, while NO_x and PN showed an upward trend from low speed to high speed condition. After installing DOC and CDPF devices, the emission reduction rates of CO, THC, PM and PN all increased gradually with the increase of vehicle speed, but the NO_x emission almost kept the same. With the increase of vehicle mileage, the DOC and CDPF device's performances of reducing CO and NO_x emissions became worse. The maximum reduction rates of CO and NO_x appeared in the first test, which was 59.8% and 9.7% respectively. The device's performances of reducing THC, PN and PM emissions were first good and then became worse. The maximum reduction rates for three pollutants appeared in the second test, which was 53.5%, 99% and 87.3% respectively.