Further developments in washcoat reaction-diffusion solutions for small diffusion resistance

Edward  Bissett, Gamma Technologies, Inc.

At last year’s CLEERS workshop, I presented the basics of a new approach to washcoat diffusion resistance based on the asymptotics of small dimensionless washcoat diffusion resistance, which is intermediate between assuming constant washcoat concentrations and the “1+1D” approach. This year I will address further aspects, including (1) dual washcoat layers, (2) relationship of this solution to those in other parameter regimes, and (3) implementation details arising from small concentrations and large rate constants. Point (2) is aided by analysis of a simple example using the Thiele modulus and, just as importantly, the Biot number. These topics should help modelers see how this asymptotic solution fits into the larger picture and how to maintain positive concentrations in practice.

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