Year: 2003
Type: article
Abstract: The cathode of a Proton Exchange Membrane (PEM) fuel cell serves to conduct reactant ( 0 2 ) gas to the catalyst layer, while removing by-products of the reaction, namely water in both liquid and vapour phase.This leads to delicate transport issues involving counter propagation, multi-phase flow sensitively coupled to the temperature profile through the phase change.We develop a 1D model of this coupled liquid-gas transport in the gas diffusion layer of a PEM fuel cell electrode.We non-dimensionalize the model, indentifying scaling regimes in which the temperature and water vapour are slaved to the temperature profile at steady-state.We find that the liquid water transport is dominated by capillary pressure, that the heat transport is dominated by diffusion, while the gas transport is convectively dominated during transients but settles down to a diffusively driven steady-state.We introduce a parameter u whice determines the ratio of liquid water to water vapour production in the catalyst layer and tune v so there is no boundary layer in the slaved water vapour concentration.In this regime the liquid water equation will de-couple from the gas and temperature equations when we are solving up to leading order.We use the reduced model to examine the role of hydrophobicity on liquid water transport and the role of temperature gradients on gas transport.I would like to extend a huge thanks to my supervisor, Keith Promislow, for all his patience, suggestions and help -I would not have written this thesis without him.
Source: Summit (Simon Fraser University)
Author: Leslie J. Fairbairn
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Funder: Ballard Power Systems
OpenAlex ID: W2113422050