余皎;王军;佟德辉;
1:潍柴动力股份有限公司技术中心
摘要：尿素选择性催化还原系统(SCR)在高催化效率下的正常运行是柴油机满足排放法规的关键因素。本文利用计算流体力学方法CFD模拟混和管中尿素水溶液的喷雾情况,对不同排气温度和排气流量下液滴的运动,水溶液蒸发后水蒸气的浓度分布进行了计算,优化排气管道形状以及优化喷射位置和喷射角度,从而避免尿素水溶液撞壁出现沉积,堵塞管路。同时对SCR载体内的流动性能进行计算,保证排气在载体入口的速度、反应物浓度分布均匀,以此来保证SCR实现高的催化效率。
关键词： 柴油机;;CFD;;SCR;;优化设计
Abstract: Liquid urea dosing systems with
selective catalytic reduction(SCR) technologies have proven to be a potentially
viable solution for meeting stringent diesel NOx emission standards.This paper
presents a simulation of the spray atomization of urea-water solutions,the
motion of urea-water droplets for a combination of different exhaust gas temperatures
and mass flow,as well as the concentration distribution of the evaporized
urea-water utilizing CFD tools.After optimization of the mounting location of
urea dosing injector and the injection angle,the issue of the exhaust pipe
clogs caused by urea deposits on exhaust pipe wall due to urea-water solutions
impingements can be eliminated.In addition,a further thorough CFD analysis of
exhaust gas flow in SCR catalyst ensures the attainments of the high NOx
conversion efficiency with SCR,and a uniform distribution of both the exhaust
gas velocity and the ammonia concentration at the entrance of the SCR catalyst
substrate.
Keywords: Diesel
Engine;SCR;Optimization;CFD
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