Gas-species dependence of permeation flow in solid oxide fuel cell porous anodes fabricated with pore formers

The gas-species dependence of permeation flow in solid oxide fuel cell anodes is experimentally and numerically investigated to clarify the Knudsen effect on the gas transport phenomena in porous media. The effective permeability of porous anodes fabricated with pore former is experimentally measured using various working gases with different mean free paths, and the effect of the working gas species on the permeation phenomena is evaluated. A linear relationship is found between the effective permeability and the mean free path of the gas species. It is clarified that the representative pore size of the porous media fabricated with the pore formers considering the permeation phenomena is larger than that quantified by the microstructural analysis. A numerical model based on the dusty-gas model is developed and three-dimensionally visualizes the flow distribution in porous anodes. The 3D simulation shows that permeation gas mainly flows through the larger pores formed by the pore formers. In addition, the molar flux distribution of the permeation flow for the gases is similar, and its absolute flow rate depends on the physical properties of the permeation gas.