Eulerian-Eulerian CFD Modeling of Multiphase Flow and Heat Transfer in Alkaline Electrolysis Cells

This study presents a comprehensive three-dimensional, two-phase, non-isothermal model for an alkaline water electrolyzer (AWE), designed to capture the intricate interactions at gas-liquid interfaces, alongside the ion transport mechanisms and electrochemical reactions. By incorporating local temperature variations and considering the spatial distribution of species, the model enhances the understanding of the thermodynamics and kinetics governing the electrolysis process. Key features of the model include the detailed representation of local gas volume fractions, hydrogen and oxygen crossover, and the coupling of electrical and electrolyte potentials. The polarization curve and overpotential analysis highlight the significant impact of current density on the efficiency of both the cathodic and anodic reactions, with particular emphasis on the greater challenges associated with oxygen evolution. The temperature gradients and mass transport phenomena, including the effects of supersaturation and the mass transfer coefficient, are shown to depend on current density, influencing the local saturation dynamics and limiting diffusion efficiency at high current densities. Additionally, the analysis of gas fraction and liquid velocity reveals the critical role of buoyancy in enhancing convective transport within the electrolyte. This model provides a state-of-the-art framework for understanding and optimizing AWE performance.