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Numerical investigation of the optimal Nafion^® ionomer content in cathode catalyst layer: An agglomerate two-phase flow modelling

Lookup NU author(s): Lei Xing, Professor Mohamed MamloukORCiD, Emeritus Professor Keith Scott

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Abstract

A two dimensional, across the channel, isothermal, two-phase flow model for a proton exchange membrane fuel cell is presented. Reactant transport in porous media, water phase transfer and water transport through the membrane are included. The catalyst layer is modelled as a spherical agglomerate structure. Liquid water occupies the secondary pores of the cathode catalyst layer to form a liquid water coating surrounding the agglomerate. The thickness is calculated by coupling the two-phase flow model with the agglomerate model. Ionomer swelling is associated with the non-uniform distribution of water in the ionomer determined from several processes occurring simultaneously, namely (1) water phase transfer between the vapour, dissolved and liquid water; (2) membrane/ionomer water content depending on the water vapour pressure; (3) a water film covering the catalyst agglomerate; (4) water transport through the membrane via electro-osmotic drag, back diffusion and hydraulic permeation. The model optimises the initial dry ionomer content in the cathode catalyst layer. The simulation results indicate that, to achieve the best fuel cell performance, the initial dry ionomer volume fraction should be controlled around 10%, corresponding to 0.3 mg cm(-2). By considering the effect of ionomer swelling on the reduction in CCL porosity and the increase in oxygen mass transport resistance, the accuracy of the model prediction is improved, especially at higher current densities. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Publication metadata

Author(s): Xing L, Mamlouk M, Kumar R, Scott K

Publication type: Article

Publication status: Published

Journal: International Journal of Hydrogen Energy

Year: 2014

Volume: 39

Issue: 17

Pages: 9087-9104

Print publication date: 05/06/2014

Online publication date: 24/04/2014

Acceptance date: 29/03/2014

ISSN (print): 0360-3199

ISSN (electronic): 1879-3487

Publisher: Elsevier

URL: http://dx.doi.org/10.1016/j.ijhydene.2014.03.225

DOI: 10.1016/j.ijhydene.2014.03.225

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