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Pore-scale analysis of diffusion transport parameters in digitally reconstructed SOFC anodes with gradient porosity in the main flow direction

Abstract:

One of the promising devices to obtain electrical and thermal energy with considerable high efficiency is the solid oxide fuel cell (SOFC). The electrical energy is the result of the electrochemical reactions that occur inside the fuel cell (FC) when the reactant gases reach the so-called three-phase boundary (TPB). The nonhomogeneous and anisotropic characteristics of the layer between the gas channel and the TPB region require a pore-scale analysis to understand the effect of microstructural configurations. The purpose of this paper is to provide understanding of the behavior of the fluid flow through the digitally reconstructed SOFC anodes, with gradient porosity in the main flow direction, using the lattice Boltzmann method (LBM). The impact of the porosity distribution over the fluid behavior is determined for different digitally created SOFC anodes. The SOFC anodes are analyzed keeping the total porosity constant, but varying the local porosity in the flow direction. The impact of a gradient porosity over the gas-phase tortuosity and the normalized effective diffusion coefficient are presented.