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A Numerical Model of a Liquid-Feed Solid Polymer Electrolyte DMFC and Its Experimental Validation

Lookup NU author(s): Dr Giovanni Murgia, Professor Ashok Shukla, Emeritus Professor Keith Scott

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Abstract

A one-dimensional, biphasic, multicomponent steady-state model based on phenomenological transport equations for the catalyst layer, diffusion layer, and polymeric electrolyte membrane has been developed for a liquid-feed solid polymer electrolyte direct methanol fuel cell (SPE-DMFC). The model employs three important requisites: (i) implementation of analytical treatment of nonlinear terms to obtain a faster numerical solution as also to render the iterative scheme easier to converge, (ii) an appropriate description of two-phase transport phenomena in the diffusive region of the cell to account for flooding and water condensation/evaporation effects, and (iii) treatment of polarization effects due to methanol crossover. An improved numerical solution has been achieved by coupling analytical integration of kinetics and transport equations in the reaction layer, which explicitly include the effect of concentration and pressure gradient on cell polarization within the bulk catalyst layer. In particular, the integrated kinetic treatment explicitly accounts for the nonhomogeneous porous structure of the catalyst layer and the diffusion of reactants within and between the pores in the cathode. At the anode, the analytical integration of electrode kinetics has been obtained within the assumption of macrohomogeneous electrode porous structure, because methanol transport in a liquid-feed SPE-DMFC is essentially a single-phase process because of the high miscibility of methanol with water and its higher concentration in relation to gaseous reactants. A simple empirical model accounts for the effect of capillary forces on liquid-phase saturation in the diffusion layer. Consequently, diffusive and convective flow equations, comprising Nernst-Plank relation for solutes, Darcy law for liquid water, and Stefan-Maxwell equation for gaseous species, have been modified to include the capillary flow contribution to transport. To understand fully the role of model parameters in simulating the performance of the DMCF, we have carried out its parametric study. An experimental validation of model has also been carried out. © 2003 The Electrochemical Society. All rights reserved.


Publication metadata

Author(s): Murgia G, Pisani L, Shukla AK, Scott K

Publication type: Article

Publication status: Published

Journal: Journal of the Electrochemical Society

Year: 2003

Volume: 150

Issue: 9

Pages: A1231-A1245

Print publication date: 01/09/2003

ISSN (print): 0013-4651

ISSN (electronic): 1945-7111

Publisher: Electrochemical Society

URL: http://dx.doi.org/10.1149/1.1596951

DOI: 10.1149/1.1596951


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