One-dimensional automotive catalyst modeling

Classical one-dimensional (1D) models of automotive catalysts with simplified representation of the fluid flow through the device have proven their effectiveness in designing catalyst systems that have met emission standards to date. This paper reviews the history of 1D catalyst modeling to illustrate the physical phenomena that exist in the catalyst along with the corresponding numerical models. To further advance the state of the art, this paper proposes a promising approach where the bulk gas equations are reformulated based on the governing equations of inviscid flow, while retaining full transient capability. While a compressible formulation of the bulk gas equations will yield the most accurate results, it is rather impractical for kinetics calibration because of its long computational time. It can, however, be used to help calibrate the simpler models by determining the actual residence time within the catalyst. On the other hand, either the incompressible or the constant velocity and density formulations can be used for fast calibration of the kinetics and for full transient cycle studies. In fact, if reactor tests are used to calibrate the kinetics, there is little difference between the compressible and incompressible formulations.