Liquid water in cathode gas diffusion layers of PEM fuel cells: Identification of various pore filling regimes from pore network simulations

A pore network model (PNM) aiming at simulating the liquid water pore filling in the cathode gas diffusion layer (GDL) in an operating PEM-fuel cell is presented. Compared to previous works, the model allows simulating a significantly larger range of operating regimes. It notably allows considering the situation where the channel gas is fully humidified both for low temperature operating conditions (similar to 40 degrees C) and standard temperature operating conditions (similar to 80 degrees C) as well as for intermediate operating temperatures. The model leads to results in good agreement with several experimental observations from the literature. This allows defining a regime diagram summarizing the main operating regimes identified in the course of the study, namely the dry regime, the dominant condensation regime, the dominant liquid injection regime, the mixed regime where both the capillarity controlled invasion in liquid phase from the adjacent layer and condensation are important. The proposed model opens up new perspectives for understanding the water transfer in proton exchange membrane fuel cells and the associated water management and performance degradation issues. (C) 2018 Elsevier Ltd. All rights reserved.