CFD simulation of time-dependent oxygen production in a manifold electrolyzer using a two-phase model

In a polymer electrolyte membrane electrolyzer cell (PEMEC), the two electrode compartments are separated by a polymer membrane. Liquid water is fed to the anode side, forming oxygen gas on the anode, and hydrogen gas on the cathode side, respectively. The respective designs of the flow field patterns are important to obtain a uniform distribution of flow, in combination with low-pressure drops, during operation. In this study, oxygen production in a manifold electrolyzer is investigated using the Computational Fluid Dynamics (CFD) method. The flow is considered unsteady, three-dimensional, and two-phase. A mixture model is applied to simulate the water consumption and oxygen production. The anode side is analyzed and after the reaction, gas bubbles are produced inside the lower surface of the electrode. The simulation is performed for 5 s. The results show that from the moment of start to 2 s is an important time for the formation of pressure and velocity balance inside the manifolds. In 0.75 s, the oxygen reaches its highest concentration and, due to its physical nature, begins to move from low to high levels in the manifold. Increasing the rate of oxygen production and reducing the pressure drop in the system can be controlled by the number of different channels.