Analysis on the influence of crack structure on MPL transmission properties

Abstract

Microcracks in micro porous layer(MPL) have influence on the liquid water and gas transport properties. A 3D MPL model was developed and Cracks at different depths and different horizontal inclination angles were added, and then the single-phase LBM model was used to simulate the liquid water transport process in the reconstructed MPL. Studies have shown that liquid water will reach a higher flow velocity in the cracks and larger interconnected gaps in the MPL. When the porosity is same, the permeability of MPL without cracks is 34.7% higher than the average permeability of the MPL with cracks in different depths. The permeability when the cracks appear on the side of the MPL is also greater than that in the interior and varies with the crack depth like a cosine function. For the different horizontal inclination angle of the crack, the permeability and the flow velocity of liquid water in the crack will increase correspondingly with the increase of the horizontal inclination angle. When the crack begins to perforate the MPL, the permeability increases significantly, forming a stable drainage channel. Some valuable discoveries were found which could provide some effective basis for structural and performance improvements of the fuel cell.