Cell Shape Influence on Mass Transfer and Backpressure Losses in an Automotive Catalytic Converter.

The development of catalytic converter systems for automotive applications is, to a great extent, related to monolith catalyst support materials and design. In this paper improvements of converter channels fluiddynamics aiming to enhance pollutant conversion in all the engine operating conditions are investigated with respect to the role of channel cross-section shape on mass and heat transfer processes. The performances of different channel sections, characteristic of ceramic and metallic monoliths, have been compared by two strategies (respectively equal cell density and equal hydraulic diameter). The results have been examined in terms of mass conversion efficiency, thermal behavior and single channel backpressure for coated and non coated single channels. 3D numerical simulations have been used as an analysis tool to give a detailed insight of in-channel phenomena. Classical shapes have been analyzed and their relative performances are reported. Improvement strategies have been analyzed as well and evaluated allowing an enhancement of pollutant conversion and thermal response with non-relevant drawbacks in terms of backpressure with regard to an analogous classical empty-channel solution.