COMPUTATION OF DEHYDRATION EFFECTS OF THE MEMBRANE IN A PEM FUEL CELL

摘要

The water management is one of crucial issues to secure a safe and reliable operation of a fuel cell system. Particularly, water flooding blocks influx of reactants in the porous materials or a lack of water in membrane may lead to decrease proton conductivity. Computational methodologies using 3D CFD are employed to conduct analyses. However, the exponentially increasing computational time and the complexity of the validation process necessary for the models are impeding further dynamic study. On the other hand, nost of the current models used for the analysis are based on the empirical polarization curve, which does not include the phenomena of water dehydration. We developed a dynamic quasi-1D model for a membrane layer appropriate for an analysis of the dehydration, which considers two aspects: (1) water removed by the outlet gases at the two electrodes; (2) water transported by diffusion and electro-osmotic forces in the membrane. Simulations have been conducted to analyze the effects of load currents and anode/cathode inlet pressure as well as flow rates on the dynamic variation of water content in the membrane and derive impacts on the behavior of the whole PEM fuel cell system.