Metal foam flow field in solid oxide electrolysis cells coupled with methane oxidation: A 3D fully coupled multiphysics analysis

Solid oxide electrolysis cells coupled with methane oxidation (SOEC-CH 4 ) are attractive as an emerging green hydrogen production technology owing to their ability to reduce electrical energy consumption by decreasing the oxygen partial pressure gradient across the electrolyte. Nonetheless, the endothermic steam methane reforming (SMR) yields a steep temperature gradient near the anode inlet, posing a significant challenge to the thermal management during the scale-up of the technology. In the present work, a fully coupled three-dimensional (3D) computational fluid dynamics (CFD) model is developed for an SOEC-CH 4 single repeating unit (SRU) with the Ni foam flow field, and validated against experimental data measured on the button cell and the large-area single cell. Numerical modeling indicates that the Ni foam flow field significantly enhances heat and mass transfer, enabling a more uniform distribution of temperature and gas composition and thereby improving the electrolysis performance, especially at high current densities. As a baseline, the maximum temperature gradient is 1.36 K · mm −1 with the conventional channel-rib flow fields for both electrodes. Upon adopting Ni foams for both electrodes, the thermal gradient drops to 1.15 K · mm −1 with a concomitant 10.5% decrease in the electrolysis voltage from 0.401 V to 0.359 V. Further parametric analyses reveal that optimizing the porosity of the Ni foam and the gas inlet flow rate can effectively mitigate the thermal gradients with slightly increased pumping power, thereby enabling savings in electricity consumption. These findings provide useful guidelines in the design of durable and robust SOEC-CH 4 stacks for practical applications.