Pore-network analysis of two-phase water transport in gas diffusion layers of polymer electrolyte membrane fuel cells

Lee, Kyu-Jin; Nam, Jin Hyun; Kim, Charn-Jung

doi:10.1016/j.electacta.2008.08.068

Cited by 112 publications

(91 citation statements)

References 46 publications

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“…This is typically done by calculating a saturation or liquid pore-volume fraction using relationships such as the Leverett J-function [5][6][7][8][9], and then using the saturation to modify the intrinsic or dry-medium transport properties using relations like those of Corey [10], (Brooks-Corey) [11], Van Genuchten [12], or Bruggemann [13][14][15]. The more intricate porelevel modeling [16][17][18][19][20][21][22][23][24] has allowed the calculation of various transport properties from a handful of statistical structural properties such as pore-and throat-size distributions, porosity, and bulktransport measurements including saturated permeabilities. While these models can provide some fundamental understanding of water percolation and movement, they are limited by a lack of measurements of the nonuniform chemical (i.e., wettability) distribution at the pore level.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…Another approach that does not rely on this assumption or constitutive relationships, but instead models the percolation process directly, is the pore network model. Lee et al observed the effect of compression on the saturation profile in the GDL which took a more linear shape under increasing compression [17]. The assumptions on the construction of the network and how the geometry changes under compression meant that the pore-entry pressure for liquid was unaffected in the through-plane direction but increased in the lateral in-plane directions thus creating preferential flow in the through-plane direction.…”

Section: Introductionmentioning

confidence: 99%

“…Excluding edge effects the average effective capillary tube diameter is calculated for all cases in both in-plane (x) and through-plane (y) directions and plotted as a function of compression ratio in Figure 7. Figure 8 shows the numerically calculated permeability according to Darcy's Law plotted against compression ratio along with a simplified K-C type permeability utilising the average effective capillary tube diameter and Equation (17). Here a constant value of C = 2.31 is used and Archie's Law is used for the tortuosity for lack of a better approximation that holds over the compression range.…”

Section: Single-phase Studymentioning

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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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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“…The network model has been used as tool to access the effective permeability, diffusivity, and capillary pressure on the PTL, since it is difficult to determine them experimentally due to the nonuniform flow distribution (15,21,22). This properties can later incorporated into a system-level fuel cell model.…”

Section: Pore-network Model and Simulationmentioning

confidence: 99%

“…The network model has been used to simulate particular percolation scenarios such as oil recovery (18), drug delivery (19) water transport in soil (20), fuel cells (13,16,(21)(22)(23)(24)(25)(26), among others. In the case of modeling liquid water movement in fuel cell, this approach has been validated against data obtained in carefully designed percolation experiments on porous layers with similar wetting and morphological properties to PTLs (27,28).…”

Section: Pore-network Model and Simulationmentioning

confidence: 99%

Modeling and Diagnostics of Fuel Cell Porous Media for Improving Water Transport

Médici¹,

Allen²

2011

ECS Trans.

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When a fuel cell is operating at high current density, water accumulation is a significant cause of performance and component degradation. Investigating the water transport inside the fuel cell is a challenging task due to opacity of the components, the randomness of the porous materials, and the difficulty in gain access to the interior for measurement due to the small dimensions of components. Numerical simulation can provide a good insight of the evolution of the water transport under different working condition. However, the validation of those simulations is remains an issue due the same experimental obstacles associated with in-situ measurements.The discussion herein will focus on pore-network modeling of the water transport on the PTL and the insights gained from simulations as well as in the validation technique. The implications of a recently published criterion to characterize PTL, based on percolation theory, and validate numerical simulation are discussed.

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Pore-network analysis of two-phase water transport in gas diffusion layers of polymer electrolyte membrane fuel cells

Cited by 112 publications

References 46 publications

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

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

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

Modeling and Diagnostics of Fuel Cell Porous Media for Improving Water Transport

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