Numerical modeling of liquid-gas two-phase flow in a hydrogen production cell

Abstract

Hydrogen, when produced through water electrolysis, has gained importance as a clean energy carrier and storage medium due to its low environmental impact. However, this production route still accounts for only a small fraction of global hydrogen production, mainly because of the high costs associated with its limited efficiency. Among the various factors affecting process performance, the formation of gas bubbles at the electrodes during electrolysis stands out for directly influencing the ohmic voltage drop and the system’s hydrodynamics, which negatively impact energy efficiency and gas production rates. In this context, the present study carries out a detailed numerical investigation of gas-liquid two-phase flow in alkaline water electrolyzers, using CFD simulations to assess the impact of bubble characteristics, such as diameter, distribution, and interfacial forces, on flow dynamics. Monodisperse and polydisperse models were compared, allowing for analysis of the system’s sensitivity to variations in operational parameters such as electrolyte flow rate and gas generation rate. The results showed that bubble size heterogeneity significantly affects gas phase distribution, recirculation patterns, and the stability of the gas layer near the electrode, reinforcing the importance of using models that more accurately represent physical reality. Furthermore, the analysis of bubble trajectories and gas entrapment regions contributes to a better understanding of gas residence time and provides a basis for geometric and operational optimization strategies in electrolytic cells.