Abstract
When the effects of humidification temperature on air utilization properties of PEFCs were investigated, (1) in standard humidification conditions, cell voltage decreased with increase of air utilization, (2) in low humidification conditions, cell voltage increased with increase of air utilization, (3) in high humidification and high utilization conditions, cell voltage suddenly dropped with slight increase of air utilization. We proved that based on experimentally obtained ohmic polarization, oxygen gain, and internal resistance free cell voltage during pure oxygen tests, by combining the following results we could provide an explanation for cell voltage behavior in the three cases: (1) calculation of water vapor partial pressure in the cell and change in activation polarization based on oxygen concentration decrease in the cell, (2) increase in relative humidity in the cell due to increase in air utilization, and consequent increase of concentration polarization, and (3) change in catalyst utilization rate with change in humidification temperature, and resulting change in properties such as cell voltage.
