Effect of channel rib on oxygen removal in 3D porous transport layer of proton exchange membrane electrolysis cell, a numerical investigation

Abstract

<p>Mass transfer resistance due to oxygen accumulation in the porous transport layer (PTL) of proton exchange membrane electrolysis cell (PEMEC) is a notorious problem for its high-power operation. In literature, most modeling works focus on 2D simulation of this phenomenon, while 3D investigation considering the effect of channel rib has not been conducted yet. Considering this, a two-phase flow model based on the phase field method is developed here to study oxygen behavior inside the 3D PTL with both flow channel and channel rib above it. To quantify the modeling result, variation of the oxygen saturation and the oxygen breakthrough velocity inside the 3D PTL are analyzed for different study cases. It is found that the oxygen breakthrough process generally includes three stages of bubble growth, contraction and stabilization. When oxygen is generated right below the channel rib, a significant impeding effect can be observed, leading to serious oxygen accumulation inside the PTL. To tackle this issue, an innovative method of PTL oblique perforation is further proposed, which can provide a fast track for oxygen removal and greatly alleviate its accumulation under the channel rib, so as to improve the PEMEC performance at high power densities. By the ascending of model dimension and the considering of channel rib, this work provides a deeper understanding of the gas-liquid two-phase flow inside PTL and promotes its structural optimization for future PEMECs.</p>