Effect of Relative Humidity on Temperature and Current Distributions within a Segmented H 2 /Air PEM Fuel Cell

The effect of the operating relative humidity (RH) values on the temperature and current distributions within a 5-5 segmented H2/air polymer electrolyte membrane fuel cell was studied. Different relative humidity values were applied ranging from 0 to 100%. All the measurements were done at a constant potential mode rather than a constant current mode. While the temperature distributions in front of the 5 subcells at different RH values were measured using thermocouples inserted at the back of the graphite current collectors, and the current distributions within these 5 subcells were measured using 5 potentiostats that have been used as zero resistance ammeters. The results show significant temperature gradients at the different loads as a function of the operating RH values. In addition, the fraction of current (α) passed through every subcell revealed interesting behaviors at the corresponding RH values.