Three Dimensional Temperature Distribution Analysis in Directly Internal Reforming SOFC Fuelled by Methane

High SOFC operating temperature allows direct internal reforming (DIR) of methane within the SOFC anode, which is expected to be load-following simple dispersed power system. However, temperature decrease by endothermic reforming reaction leads to carbon formation and increase of thermal stress which cause decrease in the performance and durability of SOFC cells. We have developed a reactor model coupled with computer fluid dynamics and reactions to predict three dimensional temperature distributions. Calculated temperature distributions along flow direction agree with experimentally measured ones in both cases of homogeneous and functionally-graded paper structure catalysts. Detailed three dimensional analyses of temperature distributions tell us the importance of cell structures, gas inlet position, and catalyst thickness. Then, we have extended the analysis tool to more practical model where three SOFC cells are stacked. Temperature distribution in an upstream cell has steeper gradient than that in a downstream cell. Better temperature distribution was obtained by designing functionally-graded paper structure catalysts in two dimensions, along the stacking direction and the gas flow in a cell.