Control System Design, Based On Matching The Characteristics Of A New Catalytic Transformation

Catalytic converter can effectively reduce the harmful exhaust emission, and is widely used on motor vehicle. Currently constructional design of the catalytic converter stops at the level of empirical design that it can't meet the property requirement of more and more strict motor vehicle exhaust emission regulation.In this paper, an automotive catalytic converter with Honeycomb substrate has been studied and it's found that catalytic converter efficiency cannot be given full play. To resolve this problem, a kind of design method that a deflector is put in the diffuser to farther improve catalytic converter efficiency is put forward, and the research on this method is carried out. It is shown that this design can help to increase catalytic converter efficiency. In the study, the performance of dual-bed three-way catalytic converters of conventional structure and with deflector are compared by numerical simulation and experiment. The numerical simulation results show that the flow uniformity of catalytic converter with deflector is higher than that of the conventional catalytic converter. The experiment results indicate that the light-off temperature of catalytic converter with deflector is lower than that of the conventional structure catalytic converter, the pressure loss of both catalytic converter are similar.This thesis is divided into five chapters. In the first chapter, the research backgrounds, the development and function of TWC (Three-way Catalytic Converter) are introduced. In the second chapter, the method of designing a new catalytic converter system based on matching characteristics is discussed. In the third chapter, a computational fluid dynamics (CFD) code was used to simulate the two- dimensional steady flows in the catalytic converter with the deflector. Simulation results offer a practical guide to the optimum design of TWC. In the forth chapter, the pressure lose and conversion efficiency of catalytic converters with various configurations have been measured on a steady flow rig and analyzed in theory. As a result, we can draw a conclusion that the TWC with deflector is better that the conventional TWC and havepracticability. At the same time, the experiment results demonstrate the prospect of application of CFD in construction design of catalytic converter. The last chapter is the summary, in which, the main results are given, and also some further study are presented.The research results in the present work are:(1)The deflector is designed and produced according to the technical requests.(2)The TWC with the deflector is optimized with ANSYS software then getting the optimized design method.(3) The experiment results show the resemble results with simulation. The results of the study show that a uniform velocity distribution can be obtained with the deflector.(4) As a result, optimum design criterion of catalytic converter is put forward. Besides, prospect of application of computational fluid dynamics in construction design of catalytic converter is discussed.