Improvement of flow field uniformity and temperature field in gasoline engine catalytic converter

Abstract

The uneven temperature field, flow field, and internal low temperature of the catalytic converter can cause substrate thermal deformation and catalytic ability decrease, which is not conducive to the service life of catalytic converter and control of automotive pollutants emission. A novel substrate structure with uniformly changes cell density and a new heater of three layers diffuser with optimized flow field uniformity are proposed. Their application in catalytic converter can effectively improve the above problems. Firstly, physical and mathematical models of the new catalytic converter were established, and the accuracy was verified by experiments. Next, the flow characteristics and catalytic performance was analyzed. Finally, the effects of different parameters on catalytic performance and temperature were analyzed. The results show that: (1) Compared with traditional catalytic converter, gas uniformity and NO conversion efficiency of the new catalytic converter are increased by 0.0885% and 13.66%, respectively, improving flow field uniformity and NO conversion. (2) The NO conversion efficiency increases and then decreases with adding of electric power, exhaust inlet temperature and exhaust inlet velocity; substrate temperature increases with adding of electric power and exhaust inlet temperature, but decreases with increase of exhaust velocity. During heating time, the NO conversion efficiency and substrate temperature first increase and then tend to stabilize. After heating is stopped, the NO conversion efficiency and substrate temperature will decrease. (3) The field synergy theory shows that synergy angle cosβ tends to − 1 with increase of electric power, which means convective heat transfer effect inside substrate becomes worse. (4) The grey relational analysis shows that exhaust inlet temperature is a key factor affecting the new catalytic converter performance.