The influences of inlet anode and c

The influences of inlet anode and cathode humidification can be utilized in two ways to control the performance of PEM fuel cell, and each is now illustrated by using a simulatedexample. The first example relates to the case when a PEM fuel cell is intended to operate at static condition and an absolute maximum power density is always desired, such as in grid-connected power generation. For analysis, a comparison between the highest and lowest maximum power density under each air stoichiometry value is made, as shown in Fig. 8.They correspond to the highest and lowest maximum power density extracted from the nine output power curves plotted in Fig. 4 or Fig. 5. It is interesting and important to note that the maximum power density attained under a given air stoichiometry can vary significantly depending on the inlet anode and cathode humidification conditions under which a PEM fuel cell operates. For example, under one air stoichiometry, 0.37 W cm2 is obtained when both anode and cathode are fully humidified, but it can be improved significantly to0.54 W cm2 by simply reducing the inlet relative humidity at cathode from 100% to 20%. For other air stoichiometry values, different absolute maximum power density values can beobtained similarly