Effect of the downstream blockage induced under-rib convection on oxygen feeding in a PEMFC with parallel flow field

Abstract In the parallel flow field of a proton exchange membrane fuel cell (PEMFC), liquid water could totally block a channel, potentially inducing under-rib convection between the blocked channel and adjacent unblocked ones. This work establishes a three-dimensional PEMFC model with three parallel-connected channels on the cathode side, specifically focusing on the middle channel, which simulates blockage caused by liquid water. Our findings indicate that the blockage-induced under-rib convection could reach velocities up to 0.1 m s −1 , suggesting that it plays a key role in maintaining oxygen supply to the catalyst layer despite the blockage. However, reducing the gas diffusion layer’s permeability to a tenth of its intrinsic value significantly weakens this convection, leading to localized oxygen starvation and up to 15% performance loss. These findings highlight the critical role of under-rib convection in mitigating the adverse effects of channel blockages on PEMFC performance and underscore the need for optimized design and operational strategies to manage liquid water within the cell.