Determination of permeability in fibrous porous media using the lattice Boltzmann method with application of PEM fuel cells.

摘要

The permeability of the porous transport layer is an important parameter in the computational fluid dynamics modelling of polymer electrolyte membrane fuel cells. The porous transport layer is a fibrous porous media with an anisotropic microstructure with two directions of interest (through-plane and in-plane). This thesis uses the lattice Boltzmann method to determine the permeability in idealised versions of the porous transport layer. This is done by a numerical experiment to determine the influence of porosity and fiber angle on the anisotropic permeability. It was found that the permeability is anisotropic and that permeability is a strong function of porosity. It was also found that permeability in the in-plane direction was strongly influenced by fiber angle as well as porosity. A number of other interesting results were also found. First, the use of perpendicular fibers in neighbouring layers can serve as an approximation to geometries with random fiber angles. Second, it was shown that using random locations of fibers results in different permeability values than those achieved using an ordered array. Work has been done in this study that provides a basis for study multiphase flow in the PTL including implementing a method for multiphase flow. The results of this study can be used to give numerical values for the permeability in computational fluid dynamics models as well as to provide a basis for the engineering of porous transport layers to have ideal permeability characteristics.