Numerical study of ceramic catalytic turbine technology for emission reduction during vehicle warm-up

Abstract

Ceramic Catalytic Turbine (CCT) Technology is expected to become an important means to reduce vehicle emissions, especially during engine warm-up. In this paper, catalytic reaction was numerically simulated in 3D for a CCT on a gasoline engine during the warm-up period. The results showed that turbulence in the turbine promotes catalytic activity; CCT starts to significantly affect exhaust pollution since turbine inlet temperature of 550 K; the conversion efficiency of harmful gas in exhaust rises sharply when turbine inlet reaches 575–625 K; when the inlet temperature is about 720 K, the conversion efficiencies of C₃H₆, CO, and NO reach 23.7%, 21.1%, and 15.5%, respectively. Meanwhile the gas temperature is increased by about 30 K at turbine outlet. In addition, during the process of numerical modeling and calculation, it is found that minor change in boundary layer thickness has a negligible impact on the simulation. However, an extremely thin boundary layer will cause computational divergence. The intensity of catalytic reaction can influence the convergence of numerical calculation, while the moving average of the catalytic reaction with the turbine inlet temperature, in return, can reveal the catalytic light-off process.