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Investigation of effects of non-homogenous deformation of gas diffusion layer in a PEM fuel cell

Wang, Jiatang LU ; Yuan, Jinliang LU ; Yu, Jong-Sung and Sundén, Bengt LU (2017) In International Journal of Energy Research
Abstract

Proton exchange membrane fuel cells have been promoted due to improved breakthrough and increased commercialization. The assembly pressure put on a single cell and a fuel cell stack has important influence on the geometric deformation of the gas diffusion layers (GDLs) resulting in a change in porosity, permeability, and the resistance for heat and charge transfer in proton exchange membrane fuel cells. In this paper, both the finite element method and the finite volume method are used, respectively, to predict the GDL deformation and associated effects on the geometric parameters, porosity, mass transport property, and the cell performance. It is found that based on the isotropic Young's modulus and the finite element method, the... (More)

Proton exchange membrane fuel cells have been promoted due to improved breakthrough and increased commercialization. The assembly pressure put on a single cell and a fuel cell stack has important influence on the geometric deformation of the gas diffusion layers (GDLs) resulting in a change in porosity, permeability, and the resistance for heat and charge transfer in proton exchange membrane fuel cells. In this paper, both the finite element method and the finite volume method are used, respectively, to predict the GDL deformation and associated effects on the geometric parameters, porosity, mass transport property, and the cell performance. It is found that based on the isotropic Young's modulus and the finite element method, the porosity and thickness under a certain assembly pressure are non-homogeneous across the fuel cell in the in-plane direction. The variations of the porosity change and compression ratio in the cross-section plane are localized by three zones, that is, a linear porosity zone, a constant porosity zone, and a nonlinear porosity zone. The results showed that the GDL porosity and compression ratios maintain linear and nonlinear changes in the zone above the shoulders and the zone under the channel but close to the shoulder, respectively. However, a constant value is kept above the middle of the channel. The obtained non-homogeneous porosity distribution is applied together with the deformed GDL for further computational fluid dynamics analysis, in which the finite volume method is implemented. The computational fluid dynamic results reveal that a higher assembly pressure decreases the porosity, GDL thickness, gas flow channel cross-sectional areas, oxygen diffusion coefficient, oxygen concentration, and cell performance. The maximum oxygen mole fraction occurs where the maximum porosity exists. A sufficient GDL thickness is required to ensure transfer of fresh gas to the reaction sites far away from the channel. However, the reduction of porosity is a dominating factor that decreases the cell performance compared with the decreased gas channel flow area and GDL thickness in the assembly condition. Therefore, the assembly pressure should be balanced to consider both the cell performance and gas sealing security.

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author
organization
publishing date
type
Contribution to journal
publication status
epub
subject
keywords
Assembly pressure, Deformed GDL, Modeling, PEM fuel cells, Porosity, Transport phenomena
in
International Journal of Energy Research
publisher
John Wiley & Sons
external identifiers
  • scopus:85019571321
ISSN
0363-907X
DOI
10.1002/er.3774
language
English
LU publication?
yes
id
7c2bae69-8879-48f1-a002-7566b516be2f
date added to LUP
2017-06-13 10:44:19
date last changed
2017-06-13 10:44:19
@article{7c2bae69-8879-48f1-a002-7566b516be2f,
  abstract     = {<p>Proton exchange membrane fuel cells have been promoted due to improved breakthrough and increased commercialization. The assembly pressure put on a single cell and a fuel cell stack has important influence on the geometric deformation of the gas diffusion layers (GDLs) resulting in a change in porosity, permeability, and the resistance for heat and charge transfer in proton exchange membrane fuel cells. In this paper, both the finite element method and the finite volume method are used, respectively, to predict the GDL deformation and associated effects on the geometric parameters, porosity, mass transport property, and the cell performance. It is found that based on the isotropic Young's modulus and the finite element method, the porosity and thickness under a certain assembly pressure are non-homogeneous across the fuel cell in the in-plane direction. The variations of the porosity change and compression ratio in the cross-section plane are localized by three zones, that is, a linear porosity zone, a constant porosity zone, and a nonlinear porosity zone. The results showed that the GDL porosity and compression ratios maintain linear and nonlinear changes in the zone above the shoulders and the zone under the channel but close to the shoulder, respectively. However, a constant value is kept above the middle of the channel. The obtained non-homogeneous porosity distribution is applied together with the deformed GDL for further computational fluid dynamics analysis, in which the finite volume method is implemented. The computational fluid dynamic results reveal that a higher assembly pressure decreases the porosity, GDL thickness, gas flow channel cross-sectional areas, oxygen diffusion coefficient, oxygen concentration, and cell performance. The maximum oxygen mole fraction occurs where the maximum porosity exists. A sufficient GDL thickness is required to ensure transfer of fresh gas to the reaction sites far away from the channel. However, the reduction of porosity is a dominating factor that decreases the cell performance compared with the decreased gas channel flow area and GDL thickness in the assembly condition. Therefore, the assembly pressure should be balanced to consider both the cell performance and gas sealing security.</p>},
  author       = {Wang, Jiatang and Yuan, Jinliang and Yu, Jong-Sung and Sundén, Bengt},
  issn         = {0363-907X},
  keyword      = {Assembly pressure,Deformed GDL,Modeling,PEM fuel cells,Porosity,Transport phenomena},
  language     = {eng},
  month        = {05},
  publisher    = {John Wiley & Sons},
  series       = {International Journal of Energy Research},
  title        = {Investigation of effects of non-homogenous deformation of gas diffusion layer in a PEM fuel cell},
  url          = {http://dx.doi.org/10.1002/er.3774},
  year         = {2017},
}