A theoretical study of inlet relative humidity control in PEM fuel cell

In this paper, the individual roles of inlet anode and cathode humidification, and their influences on PEM fuel cell’s electrical performance are discussed systematically by using a pseudo two-dimensional, two-phase PEM fuel cell model. It follows that the maximum power density point of a PEM fuel cell is strongly dependent on the combination of the inlet anode and cathode humidification conditions. Their influences, however, are predicted to be highly asymmetrical, with the anode and cathode humidification mainly affecting ohmic and concentration overpotential, respectively. The physical explanation to this asymmetry is given with the aid of a detailed set of simulation results. Finally, the developed understanding of their influences are employed to formulate two examples on the use of inlet relative humidity control as a simple and effective method for maximizing the volumetric power density and operating range of PEM fuel cell, respectively. ► Roles of external humidification are discussed. ► Influences of inlet anode and cathode humidification are asymmetrical. ► The use of inlet relative humidity control are formulated.