Numerical investigation of electrochemical performance of commercial solid oxide cell stacks

This study employs a computationally efficient multi-scale stack model, integrating computational fluid dynamics (CFD) and finite element method (FEM), to investigate the electrochemical performance of commercial solid oxide cell (SOC) stacks from Elcogen. By utilizing a novel homogenized approach, the model provides a comprehensive evaluation of stack behavior while significantly reducing computational complexity. Validation against experimental data for 15- and 39-cell stacks operating in both fuel cell and electrolysis modes demonstrates excellent agreement, with polarization curves matching closely and central temperature predictions showing minor discrepancies. Maximum temperature deviations are 1.5% and 2.2% for the 15- and 39-cell stacks under fuel cell mode, respectively, and 1% for the 15-cell stack under electrolysis mode. This stack-scale model highlights the influence of stack geometry and operating conditions on distributions of species, pressure, temperature, area-specific resistance (ASR), and current density. Results reveal uniform species distributions across the stacks, attributed to their innovative header design, and underscore the dominant role of ASR in shaping current density trends at the gas inflow temperature of 613 degrees C, where reverse trends are observed at the stack outlet/inlet. Additionally, the taller stack configuration amplifies thermal stress risks due to localized temperature maxima at the outlet. This study highlights the impact and potential of a stack-scale model employing a homogenized approach for efficiently advancing the understanding of the electrochemical performance of SOC stacks.