Numerical analysis of catalyst agglomerates and liquid water transport in proton exchange membrane fuel cells

Abstract

A two-dimensional computational fluid dynamics model of a proton exchange membrane fuel cell (PEMFC) was formulated by taking into account the liquid water transport through the membrane electrode assembly (MEA) on the basis of the agglomerate catalyst framework. Various modes of water transport in the PEMFC, including electro-osmotic drag, back diffusion, water generation by oxygen reduction reaction, etc., were considered in the presence of three-phase water, i.e., gas-, liquid- and dissolved-phase water. The presented model was validated with cell polarization data taken from experimental data prepared by the authors, and the agreement was good. Various parameters were investigated to analyze the influence on cell polarization and are summarized as follows: i) various compositions of Pt/C, Nafion and void in the catalyst layer and ii) various channel-to-shoulder ratios. Consequently, detailed investigations on the degree of flooding, the potential field, and polarizations were fully discussed.