Impact of the inlet flow distribution on the light-off behavior of a 3-way catalytic converter

Numerical simulations are increasingly assisting research and development in the field of emission control of automotive vehicles. Our work focuses on the prediction of the tail-pipe emissions, based on a numerical simulation of the automotive catalytic converter. Besides the prediction of the tail-pipe emissions, an understanding of the processes occurring inside a monolithic catalytic converter implies new opportunities for the design of the optimum exhaust gas system. In this paper, we present a three-dimensional transient numerical study of the influence of the velocity distribution in front of the inlet face on the thermal behavior of the monolith during the light-off of a 3-way catalytic converter. The differences in the thermal and chemical behavior due to the shape of the velocity distribution are discussed. The recently developed code DETCHEM M O N O L I T H /1/ is used for the numerical simulation. This code, for the first time, combines two-dimensional simulations of the reactive flow inside a large number of single monolith channels including a heterogeneous multi-step reaction mechanism with a transient simulation of the three-dimensional temperature field of the entire converter.