An ensemble Monte Carlo simulation study of water distribution in porous gas diffusion layers for proton exchange membrane fuel cells
Holzer, Lorenz; ; Schumacher, Jürgen (2017). An ensemble Monte Carlo simulation study of water distribution in porous gas diffusion layers for proton exchange membrane fuel cells. Journal of Electrochemical Energy Conversion and Storage, submitted Peer reviewed.; ;
Water management in proton-exchange membrane fuel cells (PEFCs) has a large impact on the performance of the device, as liquid water affects the transport properties of the gas diffusion layer (GDL). In this study we develop an ensemble-based model of the liquid water distribution in- side the GDL. Based on a water injection experiment, the wet structure of the porous medium is inspected via X-ray tomographic microscopy and, after an image segmentation process, a voxel-based meshing of the fiber, air and water domains is obtained. Starting from the obtained dry fiber structure, a Metropolis-Hastings Monte Carlo algorithm is used to obtain the equilibrium distribution of liquid water that minimizes the surface free energy of the ensemble. The different water distributions from the MC simulation and wa- ter injection experiment are identified as solution for differ- ent physical mechanisms which are both present in a run- ning fuel cell. The wet structure is then used to calcu- late saturation-dependent effective transport properties, us- ing the software GeoDict. Thereby, a strong influence of the saturation gradient on the macrohomogeneous transport properties is found.