Modelling and Validation of Water Hydration of PEM Fuel Cell Membrane in Dynamic Operations
In the present study, a novel mathematical zero-dimensional model has been formulated for the water mass balance and hydration of a polymer electrolyte membrane. This model incorporates all the essential fundamental physical and electrochemical processes occurring in the membrane electrolyte and considers the water adsorption/desorption phenomena in the membrane. The effect of diffusivity model, surface roughness and water content driving force is considered. The model is validated against experimental data.
In the results it is shown that the fuel cell water balance calculated by this model display better fit with experimental data-points compared with model where only water transport equilibrium were considered. We conclude that this discrepancy is due a different rate of water transport when membrane absorption/ desorption is considered in the model.
Many studies have erroneously considered fuel cell membrane in equilibrium condition disrigarding non-ficknian behavior of the cell membrane. For this reason the model presented in this study becomes useful when studying PEM fuel cell system in dynamic conditions.