Two polytetrafluoroethylene distribution effects on liquid water dynamic behavior in gas diffusion layer of polymer electrolyte membrane fuel cell with a pore-scale method

Tao Lai and Zhiguo Qu

Energy, 2023, vol. 271, issue C

Abstract: The water management capacity of the gas diffusion layer (GDL) is a crucial factor in improving the performance of polymer electrolyte membrane fuel cells at high current densities. Owing to different hydrophobic properties, the distribution of polytetrafluoroethylene (PTFE) significantly adjusts the distribution of liquid water within the GDL. Moreover, the combined optimization of the pore structure and hydrophobicity further affects the water discharge behavior in the GDL. In this study, an improved stochastic method is proposed to reconstruct the realistic GDL porous structure with in-plane gradient distributed porosity and a microporous layer (MPL) with bending cracks. Subsequently, two forms of nonuniform PTFE distributions in the in-plane and through-plane directions were designed. A three-dimensional multi-relaxation time D3Q19 pseudopotential multicomponent multiphase Lattice Boltzmann Method (LBM) was adopted to numerically explore the liquid water dynamic behavior in coupled GDL and MPL systems with different combinations of the gradient porosity and gradient wettability distribution. The numerical results indicated that the pore structure water-collection effect, caused by the graded distributed porosity, drives liquid water to accumulate in the layer with relatively large pores. Whereas, the hydrophilic water-collection effect, caused by the graded distributed wettability, drives liquid water to move towards and accumulate in the relatively hydrophilic layer. For in-plane distribution wettability, the coordination of the pore structure and hydrophilic water-collection effect is realized by arranging the layer with a relatively large porosity into a relatively hydrophilic layer. Then the concentration effect of liquid water and the drainage rate is enhanced. For through-plane distribution wettability, the liquid content at the GDL/MPL interface could be significantly reduced by increasing the hydrophobicity of the region in the GDL close to the MPL/GDL interface. The present study consolidates our understanding of the influence mechanism of different PTFE distributions on liquid water transport in GDL/MPL systems, contributing to the optimization of the structural design of the GDL.

Keywords: Polymer electrolyte membrane fuel cells; Gas diffusion layer; Liquid water transport process; Lattice Boltzmann method; Gradient porosity distribution; Gradient wettability distribution (search for similar items in EconPapers)
Date: 2023
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Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:271:y:2023:i:c:s0360544223003146

DOI: 10.1016/j.energy.2023.126920

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