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 DETCHEMMONOLITH /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 threedimensional
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temperature field of the entire converter.