Multi-scale modelling of a reacting flow through a porous bed using COMSOL Multiphysics®

Using the software COMSOL Multiphysics based on the finite element method, a one-dimensionnal model has been developped to predict the transient behaviour of a gas flow through a porous bed. The problem is solved at a macroscopic scale, therefore, the porous bed is seen as a continuum with adapted equations such as Darcy’s law. Because the gas phase is composed of different species, diffusive effects are taken into account. The solid matrix is composed of a metal which can absorb gas within its lattice. Therefore, chemical exchanges occur between the gaseous species and the species initially loaded in the solid phase. The chemical exchange is assumed to be rate-limited by the surface exchange taking place at the gas and solid phases interface. Thermal effects are also taken into account and coupled with the others mechanisms (convection, diffusion and chemical reaction). Finally, numerical results have been compared with experimental data from the litterature.