Modeling and simulation of three-way catalysts
Tariq Shamim, University of Michigan-Dearborn
The pollutant conversion performance of a converter is influenced by a number of physical and chemical processes that take place in gaseous and solid phases as the exhaust gases flow through the catalyst. A quantitative predictive understanding of these complex catalyst processes involving flow dynamics, heterogeneous surface reactions, and heat and mass transport mechanisms is important in accurate modeling of catalyst operation. This talk presents the results of a computational investigation on the role of chemical kinetics and convective heat and mass transport mechanisms. The study assessed the performance of various chemical kinetic schemes by comparing the results of numerical model with the experimental measurements. By showing significant differences in catalyst behavior during steady state and transient conditions, the talk also emphasizes the importance of studying the catalyst dynamic behavior. It discusses the effect of fluctuation in air-fuel ratio, which is a major contributor to transient operating conditions of catalysts. The talk elucidates the coupled response of transients and chemical kinetics on the catalyst HC, CO, and NO conversion efficiencies.