Numerical effect of random poral microstructures in stacking gas diffusion layers on water transport capability

Abstract

The gas diffusion layer (GDL) is currently manufactured from randomly stacked carbon fibers, with each layer forming a different pore structure. This investigation attempts to know the effect of the random poral microstructures on the water transport capacity. The stochastic reconstruction approach to numerically establishes random fiber distributions in GDL and a three-dimensional two-phase volume of fluid model are developed and validated. By combining the two models the liquid water transporting inside the randomly different GDLs is numerically processed. Thus, those observed relations, such as the water coverage ratio (WCR) of the fiber layer (FL) plane and gas channel wall, saturation and pressure drop, are comparable in simulations. The results show that even if the porosity of each FL is the same, the uncertainty of liquid water movement due to the random structure can cause large state deviations with different GDLs, within the studied range. They can lead to significant differences in oxygen content within the same GDL volume and ultimately results in significantly different fuel cell performance. The mechanism of the effect of the randomness of GDL microstructure on water transport capacity is beneficial for further mining valid characteristic information of FLs and structure improvement.