Investigation of transport properties of gas diffusion layer of PEMFC with metallic bipolar plates based on mechanical compression

The clamping pressure applied to proton exchange membrane fuel cell (PEMFC) stack alters the parameters related to mass transfer including porosity, permeability, conductivity and electrical contact resistance between metallic bipolar plates (BPs) and gas diffusion layers (GDLs). In this study, a model coupling mechanics and multiphase non-isothermal electrochemical is proposed, by considering the deformation of GDL, the impact of clamping pressure on a single straight channel of PEMFC is evaluated. The results show that oxygen concentration, oxygen reaction rate and current density are much lower under the rib, oxygen reaction rate gradually accumulates towards the region under the channel. With clamping pressure increasing, pressure drop increases remarkably, the average membrane water content slightly ascends, liquid water saturation near outlet of the channel increases while temperature under the rib descends. The power density enhances 13.6% from clamping pressure neglected (CPN) to 0.5MPa, and the parasitic power decreases 49.5% at the same time. However, the concentration loss occurs in advance and peak power density decreases when clamping pressure continues to increase. Although the uniformity indexes of oxygen concentration and temperature of 0.5 MPa are slightly higher than CPN, 0.5 MPa is still assumed to be the optimum clamping pressure.