Numerical Simulation of a Biogas-fueled Solid Oxide Fuel Cell and the Investigation of the Influence of Operating Conditions

Using biogas, rather than pure hydrogen, in a solid oxide fuel cell (SOFC) can help the green energy production chain. This research investigates the influence of operating conditions on the performance of a biogas-fueled SOFC. In this regard, a 3D numerical model is developed using finite volume approach and Fluent software. User Defined Functions are employed to introduce the steam reforming processes inside the SOFC. Second-order upwind scheme and SIMPLE algorithm are used for the discretization of governing equations and the pressure-velocity coupling. The results indicate that the power density first increases and then decreases by increasing the steam to fuel (S/C) ratio. Increasing the biogas methane content causes the performance of the SOFC to improve through enhancing the rates of reforming reactions. At a voltage of 0.5V and an operating temperature of 1073K, increasing the biogas methane percentage from 45% to 65%, causes the power to increase by 15%. Also, increasing the operating temperature enhances the SOFC performance through increasing the rates of reforming and electrochemical reactions and the electrolyte ionic conductivity. At a voltage of 0.5V, for a biogas methane percentage of 65%, increasing the operating temperature from 1073K to 1273K, leads to a 132% growth of power. It is also found that the optimal S/C ratio decreases with temperature and increases with biogas methane content and lies within the range of 0.3-1.2.