Effect of compression on liquid water transport and microstructure of PEMFC gas diffusion layers

Bazylak, Aimy; Sinton, David; Liu, Z.-S.; Djilali, Ned

doi:10.1016/j.jpowsour.2006.09.045

Cited by 302 publications

(160 citation statements)

References 26 publications

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“…The results agree with the observations of Bazylak et al [6] who observe preferential liquid pathways under compressed sections of a GDL and also explain the results of Gao et al [8] who observe a reduced saturation under compressed sections of a GDL before and after liquid breakthrough. The method of observation and experimental set-up is different in both of these experiments with the key difference being the location of liquid water injection.…”

Section: Saturationsupporting

confidence: 92%

“…Bazylak et al [6] Ex-situ study using fluorescence microscopy showed that 80% of liquid breakthroughs occur in compressed regions which is greater than the proportion of GDL being compressed, thus illustrating that compression creates preferential liquid pathways. The effect is attributed to the hydrophobic PTFE coating being damaged leading to the creation hydrophilic pathways.…”

Section: %mentioning

confidence: 99%

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The effects of compression on single and multiphase flow in a model polymer electrolyte membrane fuel cell gas diffusion layer

Tranter

Burns

Ingham

et al. 2015

International Journal of Hydrogen Energy

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A two-dimensional study of an idealised fibrous medium representing the gas diffusion layer of a PEMFC is conducted using computational fluid dynamics. Beginning with an isotropic case the medium is compressed uni-directionally to observe the effects on single and multiphase flow. Relations between the compression ratio and the permeability of the medium are deduced and key parameters dictating the changes in flow are elucidated. The main conclusions are that whilst compression reduces the absolute permeability of an isotropic medium, the creation of anisotropic geometry results in preferential liquid water pathways. The most important parameter for capillary flow, in uniformly hydrophobic media, is the minimum fibre spacing normal to the flow path. The effect is less pronounced with decreasing contact angle and non-existent for neutrally wettable media.

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Section: Saturationsupporting

confidence: 92%

Section: %mentioning

confidence: 99%

The effects of compression on single and multiphase flow in a model polymer electrolyte membrane fuel cell gas diffusion layer

Tranter

Burns

Ingham

et al. 2015

International Journal of Hydrogen Energy

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show abstract

“…concentrations. Second, the above analysis has ignored a couple of issues such as GDL anisotropies [68,84,85] and compression [8,86,87], which can somewhat be accounted for by using average properties and capillary pressure -saturation curves measured under operating-type conditions. Overall, the above methodology allows for one to go beyond simple curve fits and thus can provide educated guesses to the impact of various properties.…”

Section: Updated Porous-medium Model and Modeling Methodologymentioning

confidence: 99%

Improved modeling and understanding of diffusion-media wettability on polymer-electrolyte-fuel-cell performance

Weber¹

2010

Journal of Power Sources

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A macroscopic-modeling methodology to account for the chemical and structural properties of fuel-cell diffusion media is developed. A previous model is updated to include for the first time the use of experimentally measured capillary pressure -saturation relationships through the introduction of a Gaussian contact-angle distribution into the property equations. The updated model is used to simulate various limiting-case scenarios of water and gas transport in fuel-cell diffusion media. Analysis of these results demonstrate that interfacial conditions are more important than bulk transport in these layers, where the associated mass-transfer resistance is the result of higher capillary pressures at the boundaries and the steepness of the capillary pressuresaturation relationship. The model is also used to examine the impact of a microporous layer, showing that it dominates the response of the overall diffusion medium. In addition, its primary mass-transfer-related effect is suggested to be limiting the water-injection sites into the more porous gas-diffusion layer.

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“…Generally speaking, increasing compression improves the electric conductivity of GDL [25,26] and decreases the contact resistance at the interfaces [27][28][29][30]. Furthermore, the preferential pathway for liquid water transport may be created in the compressed part of the GDL [31][32][33]. While a certain compression pressure is necessary, excessive compression impedes reactant transport by decreasing GDL porosity [34,35] and may also damage typical paper type GDLs and other components [31,[36][37][38].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the preferential pathway for liquid water transport may be created in the compressed part of the GDL [31][32][33]. While a certain compression pressure is necessary, excessive compression impedes reactant transport by decreasing GDL porosity [34,35] and may also damage typical paper type GDLs and other components [31,[36][37][38]. Thus, an optimum compression pressure and compressed thickness, which trades off these competing issues, has to be identified for each system.…”

Section: Introductionmentioning

confidence: 99%

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

Nitta¹,

Himanen

Mikkola³

2008

Fuel Cells

104

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Faculty DepartmentAuthor ( This paper discusses the effect of compression pressure on the mechanical and thermal properties of gas diffusion layers (GDL).The stress-strain curve of the GDL revealed one nonlinear and two piecewise linear regions within the compression pressure range of 0 to 5.5 MPa. The thermal conductivity of the compressed GDL was found to be independent of the compression pressure and was determined to be 1.18 ± 0.11 W m-1 K-1. The thermal contact resistance between the GDL and graphite was evaluated by augmenting experiments with computer modeling. The thermal contact resistance decreased nonlinearly with increasing compression pressure. According to results here, the thermal bulk resistance of the GDL is comparable to the thermal contact resistance between the GDL and graphite. A simple one dimensional model predicted a temperature drop of 1.7-4.4 ˚C across the GDL and catalyst layer depending on compression pressures.

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Effect of compression on liquid water transport and microstructure of PEMFC gas diffusion layers

Cited by 302 publications

References 26 publications

The effects of compression on single and multiphase flow in a model polymer electrolyte membrane fuel cell gas diffusion layer

The effects of compression on single and multiphase flow in a model polymer electrolyte membrane fuel cell gas diffusion layer

Improved modeling and understanding of diffusion-media wettability on polymer-electrolyte-fuel-cell performance

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

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