Monolith Continuum Model

In the continuum model approach, the two-dimensional transient energy equation under the finite volume approach for the entire monolithic structure was solved. 

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Roy and Gidaspow (13-14) developed two-dimensional continuum models to describe cross-flow monolithic heat exchangers and catalytic reactors. 

A preliminary modelling analysis involved the parametric study of a multi-tubular externally-cooled fixed-bed reactor for a generic selective oxidation process, where the catalyst load consisted of cylindrical honeycomb monoliths with washcoated square chaimels, made of highly conductive supports. In this early work, the attention was focused on the effect of catalyst design. Simulation results were generated by a steady-state, pseudo-continuous 2D monolithic reactor model, where the catalyst is regarded as a continuum consisting of a static, thermally connected solid phase... 

Fig. 5.1 Schematic of the continuum model for the combustor monolith structure...

The two-dimensional temperature field of the monolith is presented for a selected case in Fig. 5.9, representative of the continuum model simulations. Mean outlet gas temperatures computed for the individual reactor channels allowed for an estimate of the average monolith exhaust gas temperature. In the case of Fig. 5.9, the computed outlet gas temperature was at 1,089 K, as opposed to a measured value of 1,041 K for the same experimental conditions. 

A propane-fueled, catalytic, mesoscale combustor was investigated numerically and expetimentaUy to assess its apphcabihty for a portable, gas-turbine-based power generahon system. After detailed parametric numerical studies of a single catalyhc channel, a subscale model of the metallic catalytic combustor was constructed. Experimental testing verified the suitability of the proposed mesoscale combustor after meeting flie required power output at the nominal mass throughput. A continuum model was used to simulate the two-dimensional temperature field of the monolith and allowed for a detailed description of the heat loss mechanisms in the monolith. 

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