Pollution Research Paper

CFD ANALYSIS OF ELECTRICALLY HEATED CATALYTIC CONVERTER TO REDUCE COLD START EMISSION IN GASOLINE ENGINE

S. PRAKASH, M. PRABHAHAR, M. VENKATRAMAN, VEMURI LAKSHMINARAYANA AND M. SARAVANA KUMAR

Abstract

Cold start emissions represent the greatest concentration of emissions from today‘s catalyst equipped vehicle. The existing catalytic converters are successful in reducing emissions after engine warm-up. The catalyst is not active during this warm-up period due to the lower temperatures during starting. The vehicle tail pipe emissions can be excessive for a period of one to two minutes following the cold start. Any strategy to significantly reduce vehicle emissions, therefore, needs to address the cold start operating. One strategy to reduce the quantity of pollutants emitted during the cold start operation is to have the catalyst active at the time the engine starts. Electrically heating the catalyst is an option to achieve catalyst activity during cold start. The goal is to have an active catalyst, capable of neither controlling cold start emissions to the neither levels achieved during nor mal running of the engine. The approach taken to solve this problem is to create a thermal model and perform thermal analysis of the different configurations using CFD code. The paper addresses the issue of modelling the transient thermal behavior of the Electrically Heated Metal Catalytic Converter (EHMCC) of an exhaust system using a CFD code will help to produce a more effective catalytic converter that uses less power. The model considers the different design used in the construction and for the involved heat transfer mechanisms. Different design configurations and materials have been simulated; to evaluate the influence on catalyst light-off time based on the temperature. Specific experimental tests have been carried out to validate the calculation results and the agreement was reasonably good. The paper presents an application of the CFD simulation to the prediction of the influence of various EHMCC configurations. The model has been setup using a commercial 3D CFD code. The model ignores the catalyst chemical reactions. The model shows a good correlation between experimental and simulated data during the first 120 seconds. The computational procedure has already proved to be useful in predicting and understanding better the transient behaviour of a close coup led catalyst and its thermal light-off time.