柴油机低温工况下SCR尿素喷射及NH3分布特性研究  

Research on urea injection and NH3 distribution characteristics of scr in diesel engine under low-temperature working conditions

作　　者：和志高 杨树启 郭宇辰 杨继孔 杨辉 HE Zhigao;YANG Shuqi;GUO Yuchen;YANG Jikong;YANG Hui(West Yunnan University of Applied Sciences,Dali 671006,Yunnan,China;Dehong Vocational College,Dehong 678400,Yunnan,China;Inner Mongolia Agricultural University,Hohhot 010018,Inner Mongolia,China)

机构地区：[1]滇西应用技术大学,云南大理671006 [2]德宏职业学院,云南德宏678400 [3]内蒙古农业大学,内蒙古呼和浩特010018

出　　处：《农业装备与车辆工程》2024年第7期130-134,138,共6页Agricultural Equipment & Vehicle Engineering

基　　金：滇西应用技术大学校级科研项目资助(2024XJKY0005)。

摘　　要：在柴油机加装后处理系统DOC+CDPF+SCR试验研究基础上,构建并开展SCR三维CFD数值模拟,研究尿素喷射过程中液滴的生成扩散和水解蒸发,对比分析不同低温工况下NH_(3)分布特性和NH_(3)分布均匀度对NOX转化效率的影响。结果表明,在低温工况下随着尿素喷射量增大,混合器前后区域催化器内表面形成较多的尿素壁膜,持续尿素喷射易产生尿素结晶;低温工况混合器和整流器对气体流动有明显的扩散作用,但随着气流量增大,NH_(3)分布集中在载体外侧区域,导致外侧发生NH_(3)逃逸量较高;在不同低温工况下,载体入口面NH_(3)分布均匀度的增大,有效提高了NOX转化效率,减小了NH_(3)逃逸量及低温下尿素结晶的可能性。Based on experimental research on the installation of the DOC+CDPF+SCR aftertreatment system in diesel engines,a 3D CFD numerical simulation of SCR was constructed and conducted,studying the generation,diffusion,and hydrolysis evaporation of urea droplets during urea injection.Comparative analysis was done on the impact of NH_(3) distribution characteristics and uniformity on NOX conversion efficiency under different low-temperature conditions.The results indicated that under low-temperature conditions,with increasing urea injection,more urea wallfilms were formed on the surfaces inside the catalyst before and after the mixer,leading to crystallization due to continuous urea injection.The mixer and diffuser play a significant diffusive role in gas flow under low-temperature conditions.However,with increased airflow,NH_(3) distribution becomes concentrated in the outer areas of the carrier,resulting in higher NH_(3) escape on the outer side.Increasing the uniformity of NH_(3) distribution at the carrier inlet surface under different low-temperature conditions effectively enhances NOX conversion efficiency,reduces NH_(3) escape,and minimizes the possibility of urea crystallization at low temperatures.

关 键 词：低温工况 尿素壁膜 NH3分布均匀度 尿素结晶 

分 类 号：TK421[动力工程及工程热物理—动力机械及工程]