A theoretical framework for multiphysics modeling of methane fueled solid oxide fuel cell and analysis of low steam methane reforming kinetics

Abstract

Solid oxide fuel cell (SOFC) fueled by methane with low steam content is desirable from the energy efficiency and power density point of view. Improved understanding about the low steam methane fuel operation is required for advancing the technology. A rigorous and comprehensive multiphysics model for methane fueled SOFCs is described for the first time. The model considers explicitly the detailed balance of local electrical potentials for methane fueled SOFCs to ensure mathematical rigor. A commonly overlooked but important difference between the Nernst potential and the open circuit voltage (OCV) is critically analyzed. Numerical simulations with this multiphysics model show that OCV for low-steam methane fuel is sensitive to the methane steam reforming (MSR) kinetics. The steam reaction order and activation energy of MSR with low-steam methane are then determined accurately by a systematic comparison of the theoretical and experimental OCVs. Moreover, several literature MSR models are shown to be invalid for low steam methane. The multiphysics model and the deduced MSR kinetics are capable of producing the experimental I–V relations without any additional parameter adjustment, demonstrating the predictive power of the theoretical method.