基于XCT的气体扩散层传输特性孔尺度模拟

PORE-SCALE SIMULATION OF GAS DIFFUSION LAYER TRANSPORT CHARACTERICS BASED ON XCT

为了探究质子交换膜燃料电池气体扩散层中孔隙率对各向异性传输特性的影响,先利用X射线计算机断层扫描(XCT)可视化技术方法对Freudenberg H2315 GDL气体扩散层进行三维微观结构重构,随后利用孔尺度模型分别研究了气体有效扩散率、曲度、有效电导率、有效热导率与孔隙率的关系,利用格子-玻尔兹曼模型研究液态水渗透率在厚度方向和平面内方向与孔隙率的关系,以及液态水饱和度和毛细压强的关系。结果表明:孔隙率对传输特性有显著的影响,Freudenberg H2315 GDL气体扩散层表现出明显的各向同性。

To investigate the effect of porosity on the anisotropic transport properties in the gas diffusion layer of proton exchange membrane fuel cells(PEMFC),the 3D microstructure of the Freudenberg H2315 gas diffusion layer is reconstructed firstly by using X-ray computed tomography(XCT)visualization technology.Then,the relationship between the gas effective diffusivity,tortuosity,effective electrical conductivity,effective thermal conductivity and porosity are studied by using the pore-scale model.The relationship between liquid water permeability in the through-plane and in-plane and porosity and the relationship between liquid water saturation versus capillary pressure are solved by using the lattice-Boltzmann model.The results show that the porosity has a significant effect on the transport properties,and the Freudenberg H2315 gas diffusion layer exhibits obvious isotropy.