| dc.description.abstract | Effects of various flow field designs and operating conditions on the flow and electrical resistances and the performance of proton exchange membrane fuel cells (PEMFC) are investigated. Nafion 117 membranes are used in the work. Operating conditions studied include humidification temperature, cell temperature, types of oxidizers, back pressure.
The measurement results show that PEMFC, in low temperature environment, starts up quickly and reaches stable condition very fast. For graphite bipolar plate, the optimal flow channel width is found to be 1mm by considering flow and electrical resistances. For the channel widths studied, the cell performance may very to an extent of 16 percent. If we fix the total flow channel area, then the performance variation is reduced to 8 percent, and the optimal channel width is found to be 1.6mm. Increase the operating temperature and back pressure of improves the performance. However, if the cell temperature goes too high, the membrane may dry out, and the cell performance will decrease. Increasing the humidification temperature increases the water content of the membrane, and hence lowers the cell interior impedance. However, this method becomes less effective at higher operating temperature if the humidification vapor amount is not adequately provided. | en_US |