Modeling of fluid behavior and calculation of the permeability of the gas diffusion layer in PEM fuel cell using lattice Boltzmann method

摘要

In the current work, a lattice Boltzmann method (LBM) is developed to study the fluid flow through digitally reconstructed 3D models of carbon paper GDLs generated by x-ray computed tomography, and the research on permeability calculation in the gas diffusion layer is also included. The methods involves the generation of a 3D digital model of a carbon paper GDL as manufactured using x-ray images acquired through x-ray micro-tomography at a resolution of 1.74 microns. The reconstructed 3D images then read into the LB model in order to predict three orthogonal permeability tensors when pressure is prescribed in the different flow direction.The Lattice Boltzmann method (LBM), an evolving pore-scale modeling approach, has received increasing attention in computational fluid dynamics. In the LBM, fluid is represented by a distribution of particles moving on a regular lattice. The LBM is extremely appealing in porous medium simulation, because the bounce-back boundary condition is efficient to treat solidboundary. It can deal with the boundary condition more easily than other tradition method. At the inlet/outlet boundaries, a pressure boundary condition is applied. This study characterizes the relationships between anisotropic permeability and porosity for gas diffusion layer, where hydrodynamics is analyzed in detail. The results indicate that the LBM is powerful and is able to provide excellent estimation on the permeability in a porous medium. The calculated permeability is in good agreement with existing measurements. The relationship between the permeability and the porosity is fitted well with the Kozeny-Carman equation and existing results.