From Fig. 4, it can be seen that in

From Fig. 4, it can be seen that inlet anode humidification mainly affects the polarization curves of the simulated PEM fuel cell at the intermediate current density region whereohmic overpotential dominates. As shown by each matrix’s element in the figure set, the limiting current density remains virtually unchanged under various inlet anode humidification conditions when inlet cathode humidification is kept constant. On the contrary, Fig. 5 shows that the variation of inlet cathode humidification has an almost negligible effect on the polarization curves at the intermediate current densityregion, but produces a significant influence on the value of limiting current density and hence the operating range of the simulated fuel cell. From these simulated trends, it appears that the role of inlet anode and cathode humidification are asymmetrical in nature under the operating conditions being studied. Thus, we propose to consider their roles individually in the following discussion and attempt to optimize the performance of fuel cell by controlling these parameters separately.