A Computational Fluid Dynamics Analysis of Multiphase Flow in the Anode Side of a Proton Exchange Membrane Electrolyzer

A computational fluid dynamics analysis of the anode side of a proton exchange membrane (PEM) electrolyzer cell has been conducted. The geometry is symmetrical and allows for the investigation of a single feed channel and a single exhaust channel in an interdigitated flow field. The model utilizes the Eulerian approach and thus solves a full set of conservation equations for both gas and liquid phase. Moreover, it is non-isothermal and it includes phase change of water. The operating stoichiometric flow ratio results in segregated flow in the horizontal flow channels. At a current density of 1.0 A/cm2, a local hot spot with a temperature increase of 7 °C is predicted. A reduction in the operating pressure below atmospheric pressure results in a more favorable concentration ratio of water vapor to oxygen at the PTL/CL interface, and the temperature distribution is more even. However, when the outlet pressure is too low, the outlet temperature is below the inlet temperature which makes this operation mode unfeasible. Adjustment of the back pressure can generally be used to control the temperature of the electrolyzer.