轻型国六商用柴油车尾气N_(2)O排放特性试验研究  

Experimental study on N_(2)O emission characteristics of ChinaⅥlight-duty commercial diesel vehicle

作　　者：王明伟 WANG Mingwei(Xiamen Environment Protection Vehicle Emission Control Technology Center,Xiamen 361023,Fujian,China)

机构地区：[1]厦门环境保护机动车污染控制技术中心,福建厦门361023

出　　处：《柴油机设计与制造》2024年第4期35-39,共5页Design and Manufacture of Diesel Engine

摘　　要：为了研究轻型国六商用柴油车尾气的氧化亚氮(N_(2)O)排放特性,选取5台国六轻型商用柴油车进行了冷启动全球统一轻型车辆测试循环(WLTC)排放测试。结果表明:5台样车N_(2)O比排放量均高于15 mg/km,其中1台样车的比排放量为28.8 mg/km,接近法规限值(30 mg/km);在整个测试循环中,在加减速工况下N_(2)O排放体积分数易出现波动,峰值在1.5×10^(-5)上下;在试验循环的前3个速度段,样车的N_(2)O排放量水平相当,差异主要体现在超高速段;超高速段出现NH3泄漏的样车,其N_(2)O排放量也较高,在加速工况下该车辆负荷高、排温高,原排中氮氧化物(NO_(x))质量分数升高,尿素喷射量增大,多余的NH3在选择性催化还原反应器(SCR)和氨气氧化催化器(ASC)中发生氧化反应,均促进了N_(2)O的生成;在减速断油工况下,后处理管路中含氧量增加,且后处理温度下降,ASC中残余的NH_(3)发生氧化反应,仍会促进N_(2)O的生成,导致N_(2)O质量分数维持在较高水平。In order to study the N_(2)O emission characteristics of ChinaⅥlight-duty commercial die⁃sel vehicle,five ChinaⅥlight-duty commercial diesel vehicles were selected for cold start world light ve⁃hicle test cycle(WLTC)emission testing.Results show that N_(2)O emissions of all five vehicles exhibit were higher than 15 mg/km,with one vehicle reaching a specific emission of 28.8 mg/km,which is close to the limit of 30 mg/km.The N_(2)O concentration tends to fluctuate under acceleration and deceleration conditions throughout the cycle,with peak values around 1.5×10^(-5).While the N_(2)O emissions are compa⁃rable in the first three phases of WLTC,differences are primarily observed in extra high-speed phase where vehicles with NH_(3)leakage produce more N_(2)O.During acceleration conditions,the vehicle has high load and exhaust temperature,resulting in an increase in NO_(x)concentration and urea injection in the original exhaust.The excess NH_(3)undergoes oxidation reactions in selective catalytic reduction(SCR)re⁃actor and ammonia slip catalyst(ASC),which promote the generation of N_(2)O.Additionally,under decel⁃eration and fuel cut-off conditions,the oxygen concertation in the post-treatment pipeline increases and the after-treatment temperature decreases.The residual NH3 in ASC undergoes oxidation reaction,which still promotes the generation of N_(2)O and maintains a high concentration level of N_(2)O.

关 键 词：轻型柴油车 排放特性 全球统一轻型车辆测试循环(WLTC) 

分 类 号：U467.48[机械工程—车辆工程]