Study on water transport in hydrophilic gas diffusion layers for improving the flooding performance of polymer electrolyte fuel cells

Abstract

For hydrogen-based polymer electrolyte fuel cells (PEFCs), water transport control in gas diffusion layers (GDLs) by wettability distribution is useful to suppress the flooding problem. In this study, the water transport of a novel GDL with hydrophilic-hydrophobic patterns was investigated. First, we clarified that the water motion in the hydrophilic GDL with microstructures could be reproduced by the enlarged scale model. The scale model experiment also showed that the same water behavior in hydrophilic GDL can be obtained from Capillary numbers (Ca) in a range of Ca ~ 10−5 to 10−3. As the computational load is inversely proportional to Ca, the computational load could be reduced by 1/100th by using Ca ~ 10−3, which is 100 times higher than PEFC operation (Ca ~ 10−5). Finally, the simulation with Ca ~ 10−3 was performed, and we showed that the GDL with straight region of contact angle 50° minimized the water accumulation.