摘要
为研究柴油机细颗粒物排放特性，选取一台搭配SCR(selective catalytic reduction)后处理系统的国六重型柴油发动机进行世界统一瞬态循环WHTC(word harmonized transient cycle)测试。为获取对比数据，分别在原排、DPF(diesel particulate filter)后、尾排3个位置获取PN10和PN23细颗粒物数据。基于PN10和PN23排放特性，搭建紧耦合ccSCR(close coupling selective catalytic reduction)后处理系统，探究后处理系统对PN10和PN23颗粒物排放的影响。试验结果表明：尾排细颗粒物排放量随着尿素喷射量和SCR入口温度的提升而增加，其中PN10增加趋势比PN23更明显。粒径为10~23 nm细颗粒物占比与温度同样为正向关系，温度为200 ℃时占总粒径的55%，240~280 ℃时占比达到75%，280 ℃以上时占比超过80%。ccSCR与SCR相比，稳态工况下PN10与PN23排放均下降50%~80%；瞬态WHTC循环下，ccSCR的PN10和PN23排放分别为1.61×1011，2.92×1010 个/(kW·h)，对比SCR的PN10和PN23排放分别下降57.2%和62.3%。
Abstract
Based on a China Ⅵ heavy-duty diesel engine equipped with selective catalytic reduction (SCR) aftertreatment system, the fine particulate matter emission characteristics of diesel engine were tested according to WHTC.To obtain comparative data, particle numbers PN10 and PN23 were obtained from the raw exhaust pipe, the rear pipe of diesel particulate filter (DPF), and the end pipe. Based on the results of PN10 and PN23 emissions, a close coupling selective catalytic reduction (ccSCR) aftertreatment system was constructed to investigate the influence of aftertreatment system on emission characteristics of PN10 and PN23. The test results show that the fine particulate matter emissions in end pipe increase with the urea injection volume and the SCR inlet temperature, and the increasing trend for PN10 is more obvious than that for PN23. The percentage for fine particulate matters of 10-23 nm size is also positively related to temperature, which accounts for 55% of total particle size at 200 ℃, 75% at most between 240-280 ℃, and higher than 80% beyond 280 ℃. The comparison between the ccSCR route and the SCR route reveals that the ccSCR route can reduce PN10 and PN23 of steady state operating conditions by 50%-80% at each point. PN10 and PN23 emissions of transient WHTC cycle are 1.61×1011 and 2.92×1010 #/(kW·h) respectively, which reduce by 57.2% and 62.3% compared to the SCR route.
关键词
选择性催化还原 /
颗粒 /
尿素喷射量 /
SCR入口温度 /
紧耦合
Key words
selective catalytic reduction (SCR) /
particle /
urea injection amount /
SCR inlet temperature /
close coupling
张旺，吴撼明，刘强，王懋譞，李振国，邵元凯.
柴油机后处理系统对细颗粒物排放特性的影响研究[J]. 车用发动机. 2024, 0(5): 42 https://doi.org/10.3969/j.issn.1001-2222.2024.05.006
ZHANG Wang，WU Hanming，LIU Qiang，WANG Maoxuan，LI Zhenguo，SHAO Yuankai.
Influence of Diesel Engine Aftertreatment System on Fine Particulate Matter Emission Characteristics[J]. Vehicle Engine. 2024, 0(5): 42 https://doi.org/10.3969/j.issn.1001-2222.2024.05.006
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