Two-dimensional finite-element method study of the resistance of membranesin polymer electrolyte fuel cells

A two-dimensional model of fluid flow, mass transport and electrochemistry is presented to examine the effect of current density and cell pressure on the resistance of Nafion 117 membranes in polymer electrolyte fuel cells. T he finite element method is used to solve the continuity, potential and Ste fan-Maxwell equations in the flow channel and gas diffusion electrode regio ns and the concentrated solution theory equations in the membrane region. M odel calculations for concurrent flow indicate that current density and wat er flux through the membrane are non-uniform and reach a minimum at the bot tom of the membrane near the gas exit. A comparison of model results to mem brane resistance measurements in the literature is discussed. The multidime nsional nature of transport within the fuel cell is described and plots of flow streamlines, gas mole fractions and membrane water content are shown. The boundary condition for water transport across the active catalyst layer is examined. (C) 2000 Elsevier Science Ltd. All rights reserved.