柴油机NO_x选择性催化还原催化箱出口温度特性及其计算模型  

Outlet temperature characteristics for NO_x catalyst container of diesel engine SCR system and its calculation model

作　　者：仇滔[1,2] 宋鑫[1] 雷艳[1] 刘兴华[3] 梁虹[3] 

机构地区：[1]北京工业大学环境与能源工程学院,北京100124 [2]北京电动车辆协同创新中心,北京100081 [3]北京理工大学机械与车辆学院,北京100081

出　　处：《农业工程学报》2016年第6期89-94,共6页Transactions of the Chinese Society of Agricultural Engineering

基　　金：北京市教委促进人才培养综合改革基金项目(JZ005011201401)

摘　　要：在不增加出口温度传感器的条件下,为准确预测SCR(selective catalytic reduction)催化箱温度,该文在柴油发动机台架上开展SCR系统催化箱的进出口温度特性测试。并基于Mtalab/Simulink模块对SCR催化箱开展仿真计算,提出了出口温度的计算模型。结果表明:稳态工况及过渡工况下,催化箱进口温度与出口温度变化并不相同;过渡工况时,催化箱出口温度改变过程滞后于入口温度改变过程;提出的计算模型在稳态和过渡工况下均对出口排气温度有良好的预测性能,可在不增加出口排温传感器前提下,获得催化箱出口温度,从而提升了SCR温度控制精度。同时,该文将提出的算法应用到实际整车试验中,在ESC(European steady-state cycle)和ETC(European transient cycle)标准测试中,NO_x的排放量均低于国IV排放法规限值,试验测试表明该文提出的算法满足了整车的控制需求。The selective catalytic reduction（SCR） technology is considered as a highly efficient and promising aftertreatment technology for deducing the diesel engine NO_x emission. The temperature inside an SCR catalyst container is important for NO_x conversion efficiency and SCR control precision. Accurate prediction for the temperature of the SCR catalyst under the condition of transient loads has important influence on the NO_x conversion efficiency. In order to gain the detail of the temperature distribution inside the SCR catalyst container, this work designs 5 test plates with thermocouples which are mounted inside the SCR catalyst container in different places. These 5 test plates contain a serial of thermocouples located in different position to test the temperature distribution inside the SCR catalyst container. These 5plates are orderly located from the inlet to the outlet of the container, and in each plate, there are totally 17 test points successively along 2 diameters which are respectively the horizontal and vertical directions. During the experiment, the diesel engine with the SCR system is tested under the varied operation engine speeds and loads to supply the SCR catalyst container with exhaust gases of different temperatures and mass flow rates. In addition, a mathematic model is proposed to predict the catalyst temperature at the outlet based on the tested inlet temperature data of the SCR catalyst container. The mathematic model is solved based on a program which is compiled by Matlab/Simulink codes. The experimental results show that under the steady conditions, the temperature inside the SCR catalyst container decreases from the inlet to the outlet of the container along the axial direction. The reason is that as the exhaust gas flows through the SCR catalyst container, the thermal energy of the exhaust gas decreases due to the thermal energy exchanges such as heat convection,heat conduction between the exhaust gas and the catalyst carrier, the container wall, as well as the environmental atmos

关 键 词：柴油机 温度 模型 选择性催化还原 催化箱温度 控制策略 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]