A Two-Dimensional, Two-Phase, Multicomponent, Transient Model for the Cathode of a Proton Exchange Membrane Fuel Cell Using Conventional Gas Distributors

Abstract

A two-dimensional, two-phase, multicomponent, transient model was developed for the cathode of the proton exchange membrane fuel cell. Gas transport was addressed by multicomponent diffusion equations while Darcy's law was adapted to account for the capillary flow of liquid water in the porous gas diffusion layer. The model was validated with experimental results and qualitative information on the effects of various operating conditions and design parameters and the transient phenomena upon imposing a cathodic overpotential were obtained. The performance of the cathode was found to be dominated by the dynamics of liquid water, especially in the high current density range. Conditions that promote faster liquid water removal such as temperature, dryness of the inlet gas stream, reduced diffusion layer thickness, and higher porosity improved the performance of the cathode. There seems to be an optimum in the diffusion layer thickness at the low current density range. The model results showed that for a fixed electrode width, a greater number of channels and shorter shoulder widths are preferred. The transient profiles clearly showed that liquid water transport is the slowest mass-transfer phenomenon in the cathode and is primarily responsible for mass-transfer restrictions especially over the shoulder.

Thermal Conductivity and Contact Resistance of Compressed Gas Diffusion Layer of PEM Fuel Cell

“…Because of its low operating temperature, typically less than 100 ˚C, the product water often remains in liquid form within the cell. The condensed water may flood the cell which significantly hinders mass transport [1][2][3][4][5][6][7]. Therefore, flooding must be properly prevented by e.g.…”

Multiscale Modeling of Single-Phase Multicomponent Transport in the Cathode Gas Diffusion Layer of a Polymer Electrolyte Fuel Cell

“…The detailed electrochemical treatment usually limits the mathematical treatment to one-dimension (through the thickness of the cell) [5,6] or two-dimensions (through-the thickness of the cell and along the channel length) [7,8,9,10,11].…”

Transient non-isothermal model of a polymer electrolyte fuel cell

“…The GDL must allow sufficient oxygen from the cathode channel to enter the CCL, but must be sufficiently hydrophobic to expel any build-up of liquid water beyond that required for optimal hydration of the membrane. The importance of water management explains the emphasis placed on capturing the effects of (particularly) liquid water in modelling studies [1][2][3][4][5][6][7][8][9]. However, a lack of understanding of the interaction between, and transport of, the three phases of water continues to retard progress towards a predictive model.…”