基于国Ⅵ柴油机后处理系统综合性能试验研究

Comprehensive performance test of diesel engine aftertreatment system based on ChinaⅥstandard

为了研究柴油机后处理系统性能,文章搭建基于国Ⅵ标准下的柴油机后处理试验台架,采用柴油机氧化催化器(diesel oxidation catalyst,DOC)+柴油颗粒捕集器(diesel particulate filter,DPF)+选择性催化还原(selective catalytic reduction,SCR)+氨氧化催化器(ammonia slip catalyst,ASC)后处理技术路线进行试验。首先校对后处理台架中的温度和氮氧化物(NO_(x))传感器偏差,提升试验的精确性;然后通过试验研究发动机动力性能与排放性能之间的关系,分析在一定废气流量下温度、氨(NH_(3))存储量和NO_(x)转化率之间的关系;最后探究DPF载体涂敷层对后处理性能的影响。结果表明:发动机在最大转矩点,排气温度、油耗率达到最大,排放性能较差;NO_(x)转化率随着NH_(3)存储量的增加而增加,NH_(3)存储量随着温度的增加而降低;载体涂敷碱金属涂层后对发动机排放性能的影响较小。

In order to study the performance of the diesel engine aftertreatment system,this paper builds a diesel engine aftertreatment test bench based on ChinaⅥstandard,and adopts the aftertreatment technology route with diesel oxidation catalyst(DOC),diesel particulate filter(DPF),selective catalytic reduction(SCR)and ammonia slip catalyst(ASC).The test first corrected the temperature and NO_(x) sensor deviation in the aftertreatment bench,which improved the accuracy of the test.Then,the relationship between engine power and emission performance was explored through experiments,and the relationship between temperature,NH_(3) storage capacity and NO_(x) conversion rate at a certain exhaust gas flow was studied.The results show that when the engine is at the maximum torque point,the exhaust gas temperature and fuel consumption rate reach the maximum,and the emission performance is poor;the NO_(x) conversion rate increases with the increase of NH_(3) storage,and the NH_(3) storage decreases with the increase of temperature.In addition,the influence of the DPF carrier coating on the aftertreatment performance was explored,and it is shown that the carrier with an alkali metal coating has little effect on the engine emission performance.