Modeling of hydrocarbon trap systems

Hydrocarbon traps for gasoline engines are promising candidates for cold start emission control, provided that their design is based on a "systems approach". In this paper, an existing CAE methodology for exhaust after-treatment is expanded to include HC trap technology. The flow, heat transfer and chemical kinetics in a typical complex system, comprising a "barrel type" adsorber and two conventional catalysts are studied. A mathematical model is developed and applied for the computation of the flow and pressure distribution, as well as transient heat transfer in the barrel type adsorber. A physically relevant model is used to simulate HC adsorption desorption on the adsorbing material. The model is used in combination with an existing 2-d 3-way catalyst model to simulate different HC trap concepts. The aim is to understand and quantify the particular thermal response and HC retention behavior of hydrocarbon adsorber systems. Illustrative results with variable geometric parameters under realistic input conditions are presented. Copyright © 2000 Society of Automotive Engineers, Inc

Experimental and modeling study on zeolite catalysts for diesel engines

The work presented in this paper was aimed at detecting, understanding and modeling some critical behavior aspects of zeolite-containing diesel catalysts. An already available mathematical model for precious metal catalysts was used as a starting point. A specially designed set of experiments provided the information needed to improve certain modeling features. New submodels were introduced to account for hydrocarbon and H2O adsorption, as well as diffusion limitations in the zeolite. The effect of flow maldistribution during real world operation was investigated experimentally and computationally. Although a number of issues (especially regarding the DeNOx mechanisms) are not yet fully resolved, significant progress was achieved as regards the understanding and computational prediction of diesel catalyst operation