Three-dimensional numerical simulation of counter gas transport in porous anodes of solid oxide fuel cells

Abstract

The counter gas transport of hydrogen and steam in solid oxide fuel cell anodes is numerically investigated to clarify the local behavior of gases and the effect of pore structure on the gas transport. The three-dimensional analysis simulating equimolar counter transport of hydrogen and steam revealed that diffusion is dominant in fine pores, while convection is dominant in larger pores. It is also clarified that hydrogen is primarily transported in fine pores, while steam is primarily transported in larger pores at equimolar gas transport. The hydrogen transport in large pores significantly decreases as the gas concentration gradient decreases, and this suggests the importance of diffusional property at lower gas concentration gradients. On the other hand, changes in the gas concentration gradient have little effect on the correlation between steam transport and pore size. Additionally, the dependence on the gas concentration gradient becomes more pronounced with larger pore-structural scales.