Review and a Methodology to Investigate the Effects of Monolithic Channel Geometry

Abstract

A typical monolithic catalyst consists of long, narrow, square channels containing a washcoat of catalytic material. While this geometry is the most common, other shapes may be better suited for particular applications. Of interest are hexagonal, triangular, and circular channel geometries. This paper provides a succinct review of these channel shapes and their associated heat and mass transfer correlations when used in a one plus one-dimensional model including diffusion in the washcoat. In addition, a summary of the correlations for different mechanical and thermal stresses and strains are included based on channel geometry. By including the momentum equation in the model formulation with geometry specific friction factors, this work illustrates a unique optimization procedure for light off, pressure drop, and lifetime operation according to a desired set of catalyst specifications. This includes the recalculation of washcoat thickness and flow velocity through the channels when cell density changes.