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

摘要

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, π_I, π_K and π_D, 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 π_K and π_D. It was found that the dimensionless overpotential across the catalyst layer takes the form of η_(cat) = -ln π_I - f(π_K, π_D). The functional relation of f(π_K, π_D), which represents the mixture of ohmic overpotential and concentration overpotential, was then evaluated for various combinations of π_K and π_D, and finally two correlation equations for η_(cat) were proposed. The plot of f(π_K, π_D) and the proposed correlation equations are helpful for analysis, prediction and optimization of the performance of a PEM fuel cell.