A modified dusty gas model in the form of a Fick's model for the prediction of multicomponent mass transport in a solid oxide fuel cell anode

The dusty gas model (DGM) is accurate but difficult to use for describing multicomponent mass transport in porous media. Based on a reasonable approximation that is exact for binary mixtures, the DGM is reformulated in the form of a Fick's model with explicit analytical expressions for the flux of each species. The validity of the new formulation, the DGMFM, is tested using a numerical model of a solid oxide fuel cell (SOFC) anode with realistic microstructure data and partially reformed methane fuel. Methane steam reforming and the water gas-shift reaction in the anode are included in the model. The accuracy of the DGMFM is checked by systematically varying the factors that may affect the mass transport in the porous anode, such as the pore radius, porosity, tortuosity factor, anode thickness, temperature, current density and fuel composition. The comprehensive study shows conclusively that the DGMFM is highly accurate in reproducing the DGM results for all practical SOFC operations.

► The dusty gas model is transformed to provide decoupled flux expressions for easy use.
► The new formalism is tested systematically for multicomponent fuel transport in the SOFC.
► The new formulation is shown to be equivalent to the dusty gas model in all cases.
► The reason for the high accuracy of the new model is analyzed.