中文摘要：

采用计算流体力学和化学反应动力学相结合的方法,建立了车用柴油机尿素选择性催化还原（Urea-SCR）排气后处理系统的数值模型,该模型包含了尿素水溶液喷射雾化、液滴的蒸发和热解、壁面液膜和表面催化还原化学反应等过程.通过模拟分析尿素溶液喷射过程中管道壁面液膜的形成量,优化了尿素溶液喷射角度.然后对Urea-SCR催化器系统进行全尺寸模拟,研究分析了催化器内部组分浓度的分布规律.最后模拟了装有混合器的SCR系统,表明混合器可以改善SCR催化剂入口还原剂的均匀性,提高SCR系统的NOx转化效率.

英文摘要：

A model of diesel Urea-SCR aftertreatment system was proposed with CFD coupled with chemical kinetics. The model includes the spray atomization, evaporation and thermolysis of urea, wall film modeling and surface catalytic reactions in the monolith. Spray angle of urea was optimized to reduce the wall film formation on exhaust pipe. Distribution of component concentration of a full scale Urea-SCR catalyst system was simulated and analyzed. Meanwhile, the SCR system with a simple mixer was simu- lated. Results indicate that SCR mixer can enhance the uniformity of reducing agentat at the entrance of SCR catalyst and increase the NOx conversion efficiency of SCR system.