国六柴油机不同粒径颗粒物排放特性差异

Particles Emission Characteristics of Different Particle Size in China VI Diesel Engine

基于发动机台架同步测量了一台满足国六排放标准的重型柴油机在稳态工况和国六标准循环试验中PN10(10 nm以上颗粒物数量)和PN23(23 nm以上颗粒物数量)的排放,并分析了稀释比对测量结果的影响。结果表明,颗粒物的排放数量高度依赖后处理的碳累积状态,稀释比的变化会改变核态颗粒物的粒径分布;冷启动瞬态标准循环试验中,10 nm~23 nm细小颗粒物的占比在循环开始时处于最高水平,且在最初的150 s,因为油气燃烧不充分使得这一阶段的PN排放贡献了整个试验的80%以上;稳态标准循环试验中,PN10和PN23随工况的变化趋势一致,满负荷工况中对应最经济运行区的中等转速PN排放较小,偏离这一转速会导致PN增加。

Based on the methods of engine test bench,the emission of PN10(particulate number above 10 nm)and PN23(particulate number above 23 nm)for a heavy-duty diesel engine that meet the China VI emission standards in the steady state working conditions and the CHINA VI standard cycle tests were simultaneously measured,and the effect of dilution ratio on the measurement results was analyzed.The results show that the emission amount of particles is highly dependent on the carbon accumulation state of the pretreatment,and the change of the dilution ratio will change the distribution of the particle size.Within the initial of the cold start WHTC cycle,the proportion of 10 nm~23 nm fine particles was at the highest level at the beginning of the cycle,because the mixture of fuel and air combustion is insufficient,the emission of PN at first 150 s contributes more than 80%of the entire test.In the WHSC steady cycle test,PN10 and PN23 have basically the same trends under different cycle,and the emission of PN at the the full load corresponding the most economical operating region is small,and deviations from this speed will lead to an increase in PN.