| Of various existing fuel cell systems, the Polymer Electrolyte Membrane Fuel Cell (PEMFC) is the most promising, because of the simplicity of its design and low temperature operation. Water management is of concern because adequate hydration of the solid polymer electrolyte is necessary for the cell to function. In this study a commercial PEMFC was characterized emphasizing water management effects. A water saturator for the hydrogen gas and cell temperature was controlled in the experiments. The key variable for the saturator was the bath temperature. At higher cell temperatures, the membrane holds less water, and this decrease in water content causes a lower conductivity. Meanwhile, the results obtained indicate that increased humidification level in the feed gas improves the ionic conductivity of the cell. A maximum current density (74.4 mA/cm2) was obtained at a cell temperature of 45°C, operated at a bath temperature of 95°C. When membrane resistance was measured at different cell temperatures, with the same bath temperature, the resistance increased with increases in cell temperature. Membrane resistance values as high of 223.4 Ωcm2 were observed. Membrane drying was producing the higher values due to different transport uncompensated resistances and undetermined water profiles. |
