台架中冷气管长度对发动机排放影响的研究

为研究发动机台架中冷器出气口与发动机进气口之间的连接管(简称中冷气管)长度对发动机排放的影响,采用国家标准GB17691-2018 《重型柴油车污染物排放限值及测量方法(中国第六阶段)》规定的世界统一瞬态测试循环(World harmonized transient cycle,WHTC)进行相关试验研究。以整车中冷气管为基准,设计了2种发动机台架排放试验方案。第1种方案中冷气管长度大于整车中冷气管长度,第2种方案中冷气管长度等同于整车中冷气管。试验结果表明:2种试验方案的一氧化碳(CO)、氮氧化物(NOx)、碳氢化合物(HC)气态污染物测量结果相差不大:CO的偏差为1. 14%、NOx的偏差为2. 21%,HC的偏差为2. 61%;第2种方案的颗粒物(PM)比第1种方案的PM降低了67%左右。这表明台架中冷气管长度对发动机CO、NOx、HC气态污染物排放几乎没有影响,但对PM排放影响较大。

Influence of Intercooler Air Outlet Tube Length on Engine Emissions

In order to study the influence of different lengths of air tube between intercooler air out⁃let and engine intake air inlet(hereinafter referred to as the intercooler air tube)on engine emissions,relevant tests were conducted with the World harmonized transient cycle(WHTC)which is stipulated in the national standard GB17691⁃2018"Limits and Measurement Methods for Emissions from Diesel Fu⁃elled Heavy⁃duty Vehicles(ChinaⅥ)".Two schemes for engine emissions bench test were designed with the length of the intercooler air outlet tube on a vehicle as a basis.The first one was using an inter⁃cooler air tube which was longer than that on the vehicle,the second was adopting an intercooler air tube which was as same as that on the vehicle.The results of measured CO,NOx and HC gaseous pollutants of the two schemes were similar.The deviations of CO,NOx and HC were 1.14%,2.21%and 2.61%re⁃spectively.The particulate matter(PM)of the second scheme was about 67%lower than that of the first scheme.This indicates that the length of an intercooler air tube has little effect on CO,NO,HC emis⁃sions from an engine,but has a great effect on PM emissions.