The Effect of Fiber Orientation on Stochastic Reconstruction and Permeability of a Carbon Paper Gas Diffusion Layer

Abstract

By analyzing the three-dimensional digital model of a real carbon paper gas diffusion layer (GDL) reconstructed by X-ray computed tomography (CT), it was found that fibers are not distributed at any angle but within a certain range. The fiber orientation can be represented by fiber pitch (i.e., the angle between a single fiber and the in-plane direction). The effect of fiber orientation on stochastic reconstruction and transport properties (permeability) was investigated in this paper to find which fiber pitch range can achieve a better GDL on fluid flow. First, the actual fiber pitch was measured by analyzing SGL-24BA images obtained by X-ray CT. Also, seven different ranges of fiber pitch were randomly chosen to reconstruct GDL. Then, the permeability of these digital models was calculated using the Lattice Bolzmann Method (LBM) and discussed to obtain the fiber pitch range of the optimal permeability. The results show that the mean fiber pitch of SGL-24BA is 2.40° and the individual values are all less than 6°, also, the permeability of the through-plane direction increases gradually as the range of fiber pitch increases, which can be used for the structural design of carbon paper GDL.

Pore-Scale Modeling of Liquid Water Transport in Compressed Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells Considering Fiber Anisotropy

“…A GDL reconstruction method considering fiber orientation was proposed by Simaafrookhteh et al [ 24 ] and the permeability of the GDL was evaluated for through-plane and in-plane directions. Gao et al [ 25 ] stochastically reconstructed GDLs with different fiber tilt angles and found that the greater the tilt angle, the greater the permeability of the GDL. Multi-component gas flow within three GDLs with different anisotropy was simulated by Molaeimanesh et al [ 26 ], and it was found that the fiber distribution perpendicular to the rib resulted in a more inhomogeneous current density distribution on the catalyst layer surface.…”