Optimal design of the diphasic flow pattern in water electrolyzers with CFD-independent multiphysics model

Abstract

The diphasic flow in the flow channel in water electrolyzers is one of the most significant phenomena affecting the efficiency of power-to-hydrogen. The produced bubbles during electrolysis will cover the catalyst layer, isolating the contact between the electrolyte and the catalyst. The topology of the flow channel, determining the bubble distribution on the catalyst, should be well-designed to attenuate the insulated bubble effect. Aiming at maximizing the hydrogen production rate from flow topology optimization, a CFD-independent multiphysics model is proposed in this paper considering the bidirectional coupling between electrochemical reaction and diphasic flow. Unlike the traditional diphasic models whose resolving depends on CFD methods, the proposed model features a node association matrix recording the topology of the flow channel, so that the multiphysics fields can be obtained through a set of matrix equations. By comparing the results with the CFD model, the resolving of the proposed model accelerates over 50 times at maximum, while the multiphysics fields can be obtained with different flow topologies at an accuracy loss within 5% by increasing the differencing segments. Therefore, the model can be applied to the optimization of the flow topology due to outperforming mathematical properties. By weighing the bubble accumulation and pressure drop in the paralleled flow channel, the optimal topology can be acquired for minimized bubble effect with various structural parameters of the flow channel in pursuit of maximum power-to-hydrogen efficiency.