CHARACTERISTIC WATER TRANSPORT PHENOMENA IN POLYMER ELECTROLYTE FUEL CELLS

摘要

Comprehensive analytical and numerical analyses were performed, focusing on anode water loss, cathode flooding, and water equilibrium for polymer electrolyte fuel cells. General features of water concentration profile as a function of membrane thickness and current density were presented to illustrate the net effect of back-diffusion of water from the cathode to anode and the water production by the cathode catalytic reaction on water transport over a fuel cell domain. Numerical Results showed a good agreement with experimental data available in the literature for a low humidity case and analytical solutions were then compared with computational results in predicting those characteristics of water transport phenomena. Along-the-channel locations of membrane/electrode interfaces characterizing anode water loss and cathode flooding, and water activities at the channel outlets based on the continuous stirred fuel cell reactor (CSFCR) model were theoretically predicted to gain more theoretical insight into water transport in a fuel cell power system. In the present study, it was found that a thinner membrane facilitates water transport in the through-membrane direction and therefore water concentration at the anode and cathode channel outlets reaches an equilibrium state particularly at low operating current densities.