Impact of operational and design variables on the thermodynamic behavior of a simulated 500 kw ng-fueled solid oxide fuel cell stack

Abstract This paper presents a detailed analysis of the impact that some operating (e.g. fuel utilization, percentage of gas recirculation in the anode and temperature differences across the stack) and design (e.g. effective diffusivities of both the anode and cathode and the thickness of the anode) parameters of a solid oxide fuel cell stack have on its energy performance. A validated mathematical model of chemical, electrochemical and thermodynamic equations is integrated to simulate the operation of a 500 kWe anode-supported natural gas-fueled solid oxide fuel cell stack. The investigation mainly focuses on the exergy efficiency and power-to-heat ratio. Analysis of the results indicates that the operating variable with the greatest effect on the exergy efficiency of the SOFC stack is the percentage of gas recirculation at the anode, achieving a maximum of 54%. Meanwhile, both the exergy efficiency and power-to-heat ratio were more sensitive to changes in the effective anode diffusivity. Finally, the paper outlines the results in the context of a wide range of experimentally verified operations.