Digital Chemical Engineering (Dec 2021)
A 3-D multiphase model of proton exchange membrane electrolyzer based on open-source CFD
Abstract
In this study, a 3-D multiphase model of the proton exchange membrane (PEM) electrolyzer is developed on an open-source computational fluid dynamics (CFD) platform, OpenFOAM. A pseudo-coupling method is presented to consider the detailed two-phase distribution conditions at the interface between the flow channel and liquid/gas diffusion layer (L/GDL) in anode flow channel of a 3-D PEM electrolyzer model. The detailed two-phase distribution conditions can be obtained by high-speed optical images or volume of fluid (VOF) simulation results. Through this method, it is possible to predict the effect of two-phase flow existing in the anode flow channel on the transport phenomena in the porous electrode, and thus cell performance. The 3-D model is validated with experimental test results at three current density conditions (0-1, 0-2, 0-3 A cm−2) considering the existence of two-phase flow. It is found that if the two-phase flow in the anode flow channel is neglected, the simulation polarization curves will deviate from the experimental test results, especially at high current density conditions. In contrast, the simulated polarization curves manage to fit the experimental data accurately with the pseudo-coupling method, indicating that it is necessary to consider the effect of two-phase flow. In addition, this pseudo-coupling model can not only take the multi-phase mass transport into consideration but also the distribution of temperature and current density inside a PEM electrolyzer. With the help of this model, a novel double-layer flow field is proposed to enhance the performance of electrolyzer. It is found that the cell performance of the proposed flow field is 0.171 V better that of the traditional parallel flow field at 3 A cm−2. Also, the temperature distribution and current density distribution of the new flow field are more uniform, which could benefit the durability and performance of PEM electrolyzer.
