Effect of Gdl(+MPL) Compression on the PEM Fuel Cell Performance

Abstract

Two components of the PEM fuel cells play a critical role in obtaining a good performance, namely the gas diffusion layer (GDL) and the micro porous layer (MPL). The target of the reported investigation was the influence of the required gas diffusion layer compression, during stack assembly, onto PEM fuel cell performance. For developing a fuel cell it is necessary to assembly all the components together in order to ensure a good connection and to reduce the leakage problem, and this is done under a compression load. The compression applied can deform the GDL and modify its thickness, porosity, hydrophobicity and electrical resistance, and these can result in damaging or decreasing the performance of the PEM fuel cell. Also, the GDL may intrude in the flow field channels and can lead in significant disturbance of the reactants flow in the channels and consequently to a drop in the performance. Numerical simulations based on ANSYS software were carried out in order to investigate the effect of the clamping force on the fuel cell performance. Therefore, 4 geometries were considered in our study, by taking into account the uncompressed and compressed GDL and the presence or absence of MPL. Different levels of GDL compression and intrusion were considered and simulated. The 3D multiphase model revealed that the GDL compression and intrusion influence the in-plane gradient in liquid saturation, oxygen concentration, membrane water content, and especially current density profiles. Also, our study showed that inserting a micro porous layer between catalyst layer and GDL can lead to an improvement of the cell performance because it helps ensuring a good water management, reducing liquid saturation.