Determination of the anisotropic permeability of a carbon cloth gas diffusion layer through X‐ray computer micro‐tomography and single‐phase lattice Boltzmann simulation

An investigation of the anisotropic permeability of a carbon cloth gas diffusion layer (GDL) based on the integration of X‐ray micro‐tomography and lattice Boltzmann (LB) simulation is presented. The method involves the generation of a 3D digital model of a carbon cloth GDL as manufactured using X‐ray shadow images acquired through X‐ray micro‐tomography at a resolution of 1.74 µm. The resulting 3D model is then split into 21 volumes and integrated with a LB single‐phase numerical solver in order to predict three orthogonal permeability tensors when a pressure difference is prescribed in the through‐plane direction. The 21 regions exhibit porosity values in the range of 0.910–0.955, while the average fibre diameter is 4 µm. The results demonstrate that the simulated through‐plane permeability is about four times higher than the in‐plane permeability for the sample imaged and that the corresponding degrees of anisotropy for the two orthogonal off‐principal directions are 0.22 and 0.27. The results reveal that flow channelling can play an important role in gas transport through the GDL structure due to the non‐homogeneous porosity distribution through the material. The simulated results are also applied to generate a parametric coefficient for the Kozeny–Carman (KC) method of determining permeability. The current research reveals that by applying the X‐ray tomography and LB techniques in a complementary manner, there is a strong potential to gain a deeper understanding of the microscopic fluidic phenomenon in representative models of porous fuel cell structures and how this can influence macroscopic transport characteristics which govern fuel cell performance. Copyright © 2010 John Wiley & Sons, Ltd.