Knudsen Diffusion and Its Effect on PEM Fuel Cell Model

Abstract

Davat1AbstractWith an aim of optimizing the operating points of the proton exchange membrane fuel cell (PEMFC), it is necessary to understand physical mechanisms of the cell. The physical mechanisms which play the important roles in the PEMFC are the gas transport in the gas diffusion layer and the proton transport in the membrane. Tremendous equations, which require massive computational cost, are used to describe the operations of the cell. However, the Knudsen diffusion, which is one kind of the transport mechanism in the fuel cell, is usually be neglected to reduce the computational cost. This paper presents a comparative study between two types of one-dimensional (1-D) steady isothermal PEMFC models; one of which is include the effect of the Knudsen diffusion and the other one is not. The numerical results of the transport phenomena from both models have been presented. Membrane resistances from each case are computed to evaluate the effect of neglecting the Knudsen diffusion. The result has shown that neglecting the Knudsen diffusion causes about 9% relative error to the membrane resistances, which is quite significant.