Grand canonical Monte Carlo study on water agglomerations within a polymer electrolyte membrane fuel cell gas diffusion layer

Lifetime and durability is one of the most relevant topics regarding PEMFCs. Especially, investigations on water agglomerations within the porous structure of the GDL have become more and more important to completely understand the effects on the fuel cell performance. Besides experimental visualization techniques which help to gain deeper insight the water distribution within the GDL, also different modelling approaches have been developed. We are using and further developing a Monte Carlo model for simulating and analysing the water inventory within PEMFC GDLs taking into account both movements and phase transitions. This model can be employed to identify preferred regions for water agglomerations within the porous structure of the GDL dependent on the surface properties, i.e. the PTFE coverage and the individual structure of the respective material. Our model can use real GDL structures as model input which allows for a direct comparison of the resulting mean water distribution obtained by simulations to experimental results from synchrotron tomography measurements on the same GDL structures. A very good qualitative agreement of the amount of water is found and also preferred regions for water agglomerations are identified consistently for both experiment and simulation. [Display omitted] ► Development of a grand canonical Monte Carlo model on the μm-scale. ► Simple systems to show the ability of the model to correctly reproduce the properties of water. ► Water distribution within a GDL obtained from synchrotron tomography measurements. ► Mean water distribution of a GDL was analysed performing MC simulations on real GDL structures. ► Comparison of the simulation results to experimental data regarding the inner GDL water distribution.