Pore-network simulations of two-phase flow in a thin porous layer of mixed wettability: Application to water transport in gas diffusion layers of proton exchange membrane fuel cells

Kuttanikkad, S. Pulloor; Prat, Marc; Pauchet, Joël

doi:10.1016/j.jpowsour.2010.09.029

Cited by 53 publications

(47 citation statements)

References 33 publications

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“…Sinha and Wang 24 demonstrated, based on a pore-network model, that liquid water will preferentially flow through connected GDL hydrophilic networks, which could be responsible for the flooding of pores. Pore network simulations have shown that, as hydrophilic pore ratio increases, gas diffusion will decrease 25 and performance of PEMFC will decline. 26 Therefore, the fraction of hydrophilic pores is a key parameter for mass transport losses, a criterion for an optimum content of PTFE.…”

Section: Introductionmentioning

confidence: 99%

New Method for Super Hydrophobic Treatment of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells Using Electrochemical Reduction of Diazonium Salts

Thomas

Benayad

Schroder

et al. 2015

ACS Appl. Mater. Interfaces

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The purpose of this article is to report a new method for the surface functionalization of commercially available gas diffusion layers (GDLs) by the electrochemical reduction of diazonium salt containing hydrophobic functional groups. The method results in superhydrophobic GDLs, over a large area, without pore blocking. An X-ray photoelectron spectroscopy study based on core level spectra and chemical mapping has demonstrated the successful grafting route, resulting in a homogeneous distribution of the covalently bonded hydrophobic molecules on the surface of the GDL fibers. The result was corroborated by contact angle measurement, showing similar hydrophobicity between the grafted and PTFE-modified GDLs. The electrochemically modified GDLs were tested in proton exchange membrane fuel cells under automotive, wet, and dry conditions and demonstrated improved performance over traditional GDLs.

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Section: Introductionmentioning

confidence: 99%

New Method for Super Hydrophobic Treatment of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells Using Electrochemical Reduction of Diazonium Salts

Thomas

Benayad

Schroder

et al. 2015

ACS Appl. Mater. Interfaces

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“…(Bradford et al, 1997;Tsakiroglou and Fleury, 1999;Jackson et al, 2003;Gladkikh and Bryant, 2006;Kuttanikkad et al, 2011;Tsakiroglou, 2014). Under mixed-wet conditions, that characterize the majority of natural porous media (e.g.…”

Section: Introductionmentioning

confidence: 99%

Steady-state two-phase relative permeability functions of porous media: A revisit

Tsakiroglou

Aggelopoulos

Terzi

et al. 2015

International Journal of Multiphase Flow

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“…Therefore, more sophisticated models focusing only on the water transport in the GDL domain and its implications on gas transport have been developed, based either on pore network modeling, 26,27 two-phase Lattice Boltzmann models, 14,[27][28][29] or other approaches. 30,31 These models incorporate the complex geometry of the GDL on the pore scale (from X-ray micro-tomography or artificial reconstructions), but their validity is unclear due to assumptions needed e.g.…”

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confidence: 99%

Saturation Dependent Effective Transport Properties of PEFC Gas Diffusion Layers

Rosén

Eller²,

Kang

et al. 2012

J. Electrochem. Soc.

125

122

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Operating Polymer Electrolyte Fuel Cells (PEFC) under high current density conditions, causes significant losses related to liquid water saturation in the gas diffusion layer (GDL). The blockage of pores inside the material has a strong influence on its effective gas transport properties. Here we report on the combination of in-situ X-ray tomographic microscopy (XTM) of PEFC and the numerical determination of gas transport properties using Lattice Boltzmann and finite difference methods. The GDL domains (Toray TGP-H-060) of two identical cells, each with 11 mm 2 active area, were analyzed in sections of about 0.3 to 0.8 mm 2 size. Saturation levels between 0.1 and 0.4 were found, with higher saturation under the ribs. The saturated and the non-saturated states of the GDL samples were compared in order to quantify the dependence of gas phase permeability and effective relative diffusivity on liquid water saturation. Both these relative measures were found to follow power relationships of (1 − s) λ , where the exponent λ was approximately 3 for all cases except for the in-plane diffusivity where it was closer to 2.Performance of polymer electrolyte fuel cells (PEFC) at high current densities is limited by mass transport losses associated with the presence of liquid water in the porous structures. In the gas diffusion layers (GDL) this issue is particularly relevant.The porous GDL structure allows collecting current under the flow field channels and provides access for the gases under the ribs. 1 This requires a high permeability and relative diffusivity in the pore space and a high conductivity in the solid. GDLs, made from carbon fibers with diameters in the order of typically 6-8 μm, have porosities around 75% and the internal surface is treated with hydrophobing agents. The formation and transport of liquid water in the GDL is thus governed by its internal structure and surface properties, and the presence of liquid water in the pore space of the GDL influences its gas transport properties. At high current density and/or moderate temperature conditions, the oxygen transport in the cathode GDL is particularly affected, which may lead to significant overvoltages. 2,3The effective relative diffusivity of GDLs has been determined with sulphuric acid filled samples and an electrochemical method. 4,5 LaManna et al. 6 have obtained the effective relative diffusivity in a test cell by inducing mass transfer using a concentration gradient of water vapor. These methods however fail to produce saturation dependent results. Opposite to the experimental methods, effective medium theory was used to describe the diffusion through a porous medium consisting of packed spheres. 7 Later, numerical models yielded similar relations particularly for hydrophobic fibrous materials such as the GDL. Tomadakis and Sotirchos 8 used Monte-Carlo simulations in fiber structures and found that the effective relative diffusivity was strongly dependent on the fiber orientation. Nam and Kaviany 9 extended the work of Tomadakis and Sotirchos 8 and...

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Pore-network simulations of two-phase flow in a thin porous layer of mixed wettability: Application to water transport in gas diffusion layers of proton exchange membrane fuel cells

Cited by 53 publications

References 33 publications

New Method for Super Hydrophobic Treatment of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells Using Electrochemical Reduction of Diazonium Salts

New Method for Super Hydrophobic Treatment of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells Using Electrochemical Reduction of Diazonium Salts

Steady-state two-phase relative permeability functions of porous media: A revisit

Saturation Dependent Effective Transport Properties of PEFC Gas Diffusion Layers

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