Pressure losses in automotive catalytic converters

Catalytic converters in the automotive exhaust system increase the engine's exhaust back pressure, thus penalizing the vehicle's fuel economy and power output. The sensitivity of the main factors affecting the pressure losses in automotive catalytic converters was investigated based on a theoretical analysis of the logarithm derivative. A computational fluid dynamics (CFD) code was used to simulate the flow in the catalytic converters to study the effects of structures and configurations of the diffusion and contraction headers on the pressure losses. Theoretical results show that the converter pressure losses mainly result from the monolith resistance and diffusion header losses. Of the physical monolith parameters, the channel diameter has the largest impact on the monolith resistance. The inlet diffusion cone angle, inlet diffusion header configuration and outlet contraction cone angle also contribute to the pressure losses.