Three-dimensional modeling of gas-liquid flow in the anode bipolar plate of a PEM electrolyzer

Abstract

Polymer electrolyte membrane water electrolyzers (PEM-WEs) are electrochemical devices increasing in popularity and are commonly used to produce hydrogen with at least a pureness of 99.9% from water. Computational fluid dynamics is essential in PEM electrolyzer research. Most numerical models based on the electrolysis process have been developed considering a steady-state and single-phase flow. Two-phase simulation models of the anode side of the PEM-WE were generally generated using volume-of-fluid and Eulerian approaches. This study contributes to the existing discussion related to the two-phase modeling approaches. A three-dimensional mixture-approached viscosity model of the PEM-WE is developed to characterize the two-phase flow in the flow field plate. The finite-volume method was used to solve the time-dependent, isothermal model coupled within a laminar regime, oxygen defining the dispersed phase and the water the continuous phase. The two-phase flow characteristic has been investigated with the mixture model approach. The effect of the number of channels on the pressure drop behavior, velocity profile, and oxygen concentration distribution will make a novel contribution to the literature. The numerical results show that as the number of channels increases, the oxygen concentration increases, and the pressure drop decreases. It was concluded that the oxygen gas volume fraction, which is the highest at the center of the flow field plate, increases from the channel inlet to the channel outlet. This paper will give the electrolyzer cell or stack manufacturer a practical perspective before the product development.