Gas diffusion layer properties on the performance of proton exchange membrane fuel cell: pc-s relationship with K-function

Accurate capillary pressure-liquid water saturation relationship (pc-s) plays a key role in predicting the performance of proton exchange membrane (PEM) fuel cells and the two-phase flow characteristics in gas diffusion layer (GDL). In this work, a validated Leverett function (K-function) based on the experimental pc-s data for SGL24 and SGL10 series carbon paper GDL materials is incorporated into a three-dimensional and two-phase PEM fuel cell model to investigate the effects of gas diffusion layer properties on the cell performance. Special emphasis is put on Polytetrafluoroethylene (PTFE) loading (5-20 wt%) in the GDL, compression pressure (1-4 MPa) and micro-porous layer (MPL). The results show that the cell exhibits better performance when a higher PTFE loading of 20% and a lower compression pressure of 1 MPa are adopted. However, liquid water is hard to drain from the GDL with the 5 wt% PTFE loading due to the low hydrophobicity, especially under the ribs; for the high compression pressure of 4 MPa, small effective porosity caused by the pressure becomes the major resistance of water drainage. The existence of MPL is also very helpful to reduce the water saturation in the GDL.