Numerical investigations of two-phase flow coupled with species transport in proton exchange membrane fuel cells

Abstract

A 3D + 1D model is developed to investigate the effect of liquid water in cathode channels on oxygen transportation. The gas-liquid interface is tracked by volume of fluid (VOF) method and the oxygen transportation is solved by a species transport model. It is found that the existence of liquid water in channels can hinder the transportation of oxygen towards catalyst layers. The water coverage is a key factor that affects the oxygen transportation. It is influenced by the droplet numbers, volumes, contact angles and liquid regimes. Compared to the case with 0 droplet, the current densities for the cases with 6 and 12 droplets decrease by 1.4% and 10.6% respectively, for the cases with a droplet volume of 0.05 μL, 0.1 μL, 0.2 μL and 0.3 μL decrease by 1.7%, 3.9%, 9.6% and 14.9% respectively, for the cases with the contact angles of 115°, 125°, 135°, 145° and 155° decrease by 15.2%, 13.8%, 9.6%, 6.6% and 5.3% respectively. Compared to the droplet regime, the current densities of the film regime with the water volume of 1.2 μL and 2.4 μL increase by 3.6% and 9.4% respectively.