Investigation of Two-Phase Transport in Polymer Electrolyte Fuel Cell Channels Using the Volume of Fraction Method

In open-cathode polymer electrolyte fuel cell (PEFC) stacks, a significant temperature rise can exist due to insufficient cooling, especially at higher current densities. To improve stack thermal management while reducing the cost of cooling, we propose a forced air-convection open-cathode fuel cell stack with edge cooling (fins). The impact of the edge cooling is studied via a mathematical model of the three-dimensional two-phase flow and the associated conservation equations of mass, momentum, species, energy, and charge. The model includes the stack, ambient, fan, and fins used for cooling. The model results predict better thermal management and stack performance for the proposed design as compared to the conventional open-cathode stack design, which shows potential for practical applications. Several key design parameters—fin material and fin geometry—are also investigated with regard to the stack performance and thermal management.

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On the hydrophobicity and hydrophilicity of the cathode gas diffusion layer in a polymer electrolyte fuel cell

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2012.0695 ◽

2013 ◽

Vol 469 (2154) ◽

pp. 20120695 ◽

Cited By ~ 2

Author(s):

M. Vynnycky ◽

A. Gordon

Keyword(s):

Fuel Cell ◽

Polymer Electrolyte ◽

Diffusion Layer ◽

Gas Diffusion Layer ◽

Gas Diffusion ◽

Cell Performance ◽

Polymer Electrolyte Fuel Cell ◽

Liquid Region ◽

Catalytic Layer ◽

Two Phase

An anomaly in the modelling of two-phase flow in the porous cathode gas diffusion layer (GDL) of a polymer electrolyte fuel cell is investigated asymptotically and numerically. Although not commented on previously in literature, the generalized Darcy model used most commonly leads to the surprising prediction that a hydrophilic GDL can lead to better cell performance, in terms of current density, than a hydrophobic one. By analysing a reduced one-dimensional steady-state model and identifying the capillary number as a small dimensionless parameter, we find a potential flaw in the original model, associated with the constitutive relation linking the capillary pressure and the pressures of the wetting and non-wetting phases. Correcting this, we find that, whereas a hydrophilic GDL can sustain a two-phase (gas/liquid) region near the water-producing catalytic layer and gas phase only region further away, a hydrophobic GDL cannot; furthermore, hydrophobic GDLs are found to lead to better cell performance than hydrophilic GDLs, as is indeed experimentally the case.

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Through-Plane Water Distribution in a Polymer Electrolyte Fuel Cell at Various Operating Temperatures

2010 14th International Heat Transfer Conference, Volume 5 ◽

10.1115/ihtc14-23006 ◽

2010 ◽

Author(s):

Yun Wang ◽

Ken S. Chen

Keyword(s):

Fuel Cell ◽

Polymer Electrolyte ◽

Water Distribution ◽

Electrochemical Reaction ◽

Neutron Imaging ◽

Polymer Electrolyte Fuel Cell ◽

Two Phase ◽

Model Predictions ◽

Higher Temperature ◽

Operating Temperatures

A multi-dimensional mathematical model is formulated for simulating the transport and electrochemical reaction phenomena in a polymer electrolyte fuel cell (PEFC). The model describes the two-phase flows, electrochemical reaction kinetics, species transport, and heat transfer, as well as their intrinsic couplings within a PEFC. Two-dimensional model predictions are computed for the two typical operating temperatures at 40 and 80 °C. Computed results reveal that liquid water level may be lower at the higher temperature operation due to water vapor phase diffusion. Detailed water and temperature distributions are displayed to explain the water and heat transport and their interaction. The computed water-content profiles are compared with available experimental data obtained by neutron imaging.

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