柴油机不同测试循环气态污染物排放特性

Diesel Engine Gas Emission Characteristics in Different Test Cycles

相比于国六法规的发动机测试循环(WHTC和WHSC),中国汽车行驶工况发动机测试循环(CATC和CASC)更能反应我国车辆实际行驶状态。为了研究上述4种测试循环的不同,本文通过一款4L四缸柴油机,分别开展了CATC、CASC以及WHTC、WHSC下的排放测试并进行了气态污染物排放特性分析。结果表明:WHSC和CASC循环的平均排温较WHTC和CATC循环的平均排温高100℃,对应的NOx和PM排放在WHSC和CASC循环下能满足国六限值,而在WHTC和CATC循环下未能满足限值要求;CO和THC的排放则受排温和测试循环中低负荷工况占比影响较大。本文同时还总结了在不同测试循环的排气流量、转速、扭矩和平均排温等工况特性,阐述了产生差异的原因。

Compared with WHTC and WHSC,Chinese vehicle driving cycle(CATC and CASC)can better reflect the actual driving state of Chinese vehicles.In order to study the differences of the above four test cycles,a 4L four-cylinder diesel engine is applied in this paper.The emission tests under CATC,CASC,WHTC and WHSC were carried out respectively,and the emission characteristics of gaseous pollutants were analyzed.The results show that the average exhaust temperature of WHSC and CASC cycles is 100℃higher than that of WHTC and CATC cycles,and the corresponding NOx and PM emissions can meet the National VI limit values under WHSC and CASC cycles,but cannot meet the limit values under WHTC and CATC cycles.The emission of CO and THC was greatly affected by exhaust temperature and the proportion of low load condition in the test cycle.At the same time,the characteristics of exhaust flow,speed,torque and average exhaust temperature in different test cycles are summarized,and the reasons for the differences are expounded.