Modeling the catalyst layer of a PEM fuel cell cathode using a dimensionless approach

This paper presents the results of the modeling and analysis of the catalyst layer of a PEM fuel cell cathode. We nondimensionalized the governing equations and introduced three dimensionless parameters, πI, πK and πD, to simplify the description of the complicated phenomena occurring in the catalyst layer. The three dimensionless parameters indicate the resistance to oxygen reduction, the resistance to proton conduction, and the resistance to oxygen diffusion, respectively. The profiles of oxygen concentration, reaction rate, and current density in the catalyst layer were investigated in terms of πK and πD. It was found that the dimensionless overpotential across the catalyst layer takes the form of image. The functional relation of f(πK,πD), which represents the mixture of ohmic overpotential and concentration overpotential, was then evaluated for various combinations of πK and πD, and finally two correlation equations for image were proposed. The plot of f(πK,πD) and the proposed correlation equations are helpful for analysis, prediction and optimization of the performance of a PEM fuel cell.