Abstract
Further improvement in the purification performance of exhaust gas is required for the three-way catalyzers (TWC) to purify gasoline engine exhaust gas. Therefore it is necessary to investigate the purification characteristics, in detail, and improve the catalyzer geometry, etc. In this study the conversion efficiencies of exhaust gas components; CO, HC and NO in the TWC were estimated by three-dimensional calculation with the authors' GTT code, in which a catalytic reaction model was incorporated in order to analyze the thermo-fluid flow with chemical reaction in the TWC. The effects of the shapes of exhaust pipe and diffuser in the upstream part of the monolith catalyzer on conversion efficiency were investigated. It has been found that both exhaust pipe and diffuser shapes considerably affect the conversion efficiency of catalyzer, especially in the range of catlyzer activation temperature, i.e., from about 400 K to 520 K.
