三效催化转化器结构与性能耦合仿真研究

摘要

Waste gas pessure loss,conversion rate are important performance indexes of the Three Way Catalytic Converter (TWC),and are coupled with TWC structure,such as entrance divergence angle,carrier length,carrier section shape,etc.In this paper,the physical model and the work process mathematical simulation model of TWC are established.The numerical solution of heat transfer equations based on the TDMA,the momentum equation based on the velocity and pressure correction have been proposed and the simulation process is designed.The coupling simulation of the TWC structure,velocity of flow,waste gas pessure loss,conversion rate shows that:the larger the radius is,the lower velocity is in the same cross section; At the same radius,the carrier longer is,the higher the flow rate is when the TWC volume is constant; The greater the ellipticity e is,the higher the flow rate is when the TWC carrier sectional area is unchanged; The higher the entrance velocity is,the greater pressure loss is.The conversion rate of the longer carrier and smaller cross-section TWC is higher than the shorter and bigger cross-section TWC;Reduce of the TWC carrier ellipticity can increase the conversion rate.The results provide a basis for the TWC structural optimization and performance improvements,which has great practice and application value.%压力损失、废气转化率是三效催化转化器(TWC)的重要性能指标,与结构(如入口扩张角、载体长度、载体截面形状等)相互耦合.通过建立三效催化转化器物理模型与工作过程数学模型,提出了基于TDMA方法的流动与传热方程解法及基于速度与压力修正的动量方程解法,设计了仿真流程.三效催化转化器结构、流速、压力损失与转化率的耦合仿真表明:扩张角越大,在同一半径处,排气流速越大;同一截面,半径越大,流速越低;体积一定,相同的半径处,载体越长,流速越高;载体截面积不变,椭圆率e越大,流速越高;入口流速越高,压力损失越大;体积一定时,小截面长载体比大截面短载体三效催化转化器的转化率高;减小椭圆率可提高三效催化转化器转化率.研究结论为三效催化转化器结构优化和性能改进提供依据,具有重要的实际应用价值.