Effective diffusivity in partially-saturated carbon-fiber gas diffusion layers: Effect of local saturation and application to macroscopic continuum models

摘要: Abstract Macroscopic continuum models are an essential tool to understand the complex transport phenomena that take place in gas diffusion layers (GDLs) used polymer electrolyte fuel cells (PEFCs). Previous work has shown macroscopic require effective properties obtained under uniform saturation conditions get a consistent physical formulation. This issue, mostly unappreciated open literature, is addressed detail this work. To end, lattice Boltzmann simulations were performed on tomographic images of dry and water-invaded carbon-paper GDL subsamples with nearly porosity distributions. The computed diffusivity shows anisotropic dependence local similar reported for morphologically analogous GDLs. In contrast, rather isotropic, following quadratic power law. capability correlations recover layer-scale from inhomogeneous GDLs checked by global averaging. Good agreement found between upscaled results data which present taken, as well other presented literature. A higher blockage effect is, however, expected under-the-rib region operating PEFCs.