Adjusting porous media properties to enhance the gas-phase OER for PEM water electrolysis in 3D simulations

Abstract

A three-dimensional computational fluid dynamics study was employed to investigate the extent of the gas-phase contribution to the oxygen evolution reaction. The model was parametrized via comparison with experimental data. It was concluded from comparing non-isothermal and isothermal models that evaporation likely plays a key role in cell performance, along with heat generation. Porous transport layer (PTL) properties were adjusted in the model to compute the impact of such properties on cell performance. Current density increased as a result of reducing PTL permeability, increasing the liquid/gas interfacial area, and increasing porosity. Effects of the flow field plate were investigated as well. It was found that high in-plane permeability in the PTL may lead to redirection of flow in the channels, causing non-uniformity in anode conditions. Utilizing the insight from these investigations, the anode PTL properties were adjusted in an attempt to improve cell performance by regulating liquid water transport while maintaining uniformity. The simulation suggests that current can be increased by about 5–10% under constant operating conditions via changes in PTL properties.