SIMULATION OF WATER VAPOR TRANSPORT PHENOMENA IN PROTON EXCHANGE MEMBRANE FUEL CELLS (PEMFCs)

摘要

The objective of this paper is to study the influences of water vapor concentration in membrane and flow channels under the different operation conditions. The studied flow channels by CFDRC code include serpentine and interdigitated flow channels which have different gas transportation mechanisms. At the same time, the computer code, based upon Okada's one dimensional model, was built to predict the influences of the electro-osmosis effect, the foreign impurity cations and the water balance time on water concentration in the membrane by Fortran 90. Both of interdigitated and serpentine flow fields show that water vapor accumulates near the cathode outlet of the membrane. And, the serpentine flow field accumulates more water vapor than interdigitated flow field does. As the inlet water mass fraction below 10%, the drying out problem may happen to reduce current density. In addition, the foreign impurity cations may induce the stronger electro-osmosis effect and reduce the effect of water back diffusion; hence, cause the accumulating of water in the cathode. It needs more water balance time and decreases the membrane performance.