Numerical investigation on double gas diffusion backing layer functionalized on water removal in a proton exchange membrane fuel cell

Since flooding is a limiting factor of cell performance in a proton exchange membrane fuel cell (PEMFC), it is important to remove produced water effectively from GDL. In this study, a multi-layer GDL containing single micro porous layer (MPL) and double gas diffusion backing layer (GDBL) was introduced as a practical design and the effect of porosity and/or hydrophobicity of GDBL on water removal was investigated with one-dimensional steady-state model based on a capillary pressure-saturation relationship. The results shows that double GDBL with different porosity in a positive direction (GDBL with lower porosity near the MPL and GDBL with higher porosity near the flow channel) and/or different hydrophobicity in a negative direction (more hydrophobic GDBL near the MPL and less hydrophobic GDBL near the flow channel) enhances the water removal ability of the GDL compared with uniform single GDBL. Based on the results, the property arrangements of double GDBL were optimized to minimize the amount of liquid water remaining in GDL. It is expected that the amount of produced water remaining in ML-GDL can be reduced about 9.2% with optimized porosity arrangement and 5.6% with optimized hydrophobicity arrangement.