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Effective Properies of Porous Ni-metal Electrode

Electrode behaviour and performance are often modelled by considering homogeneous electrode characterized with the macroscopic averaged microstructure descriptors. The electrode thickness, their porosity, the pore dimensions, the tortuosity factor and pore connections are some of the main parameters affecting the mass transport of chemical species through the electrode/electrolyte interface. The actual Ni metal foam network was represented geometrically as a set of repeating units in the form of tetrakaidecahedron elements. The cell is idealized as the three-dimensional model by cubical nodes and cylindrical ligaments. Taking the cells in their connected state, a representative volume element (RVE) was selected based on symmetry, a one sixteenth of a single tetrakaidecahedron cell. The set of RVE’ s with various distributions of cell-sizes are generated numerically. The asymptotic expansion homogenization method is formulated for some experimentally determined examples in order to perform both localization and homogenization for the electrode surrounded in fluid. The rate of heat transfer is enhanced by conducting the heat to the material struts which have a large accessible specific surface area with high interaction with the fluid flowing through electrode. The effective properties for electrode from open-cell metal foam are determined by finite element method procedure. The effective thermal conductivity dependence upon porosity and ratio ( solid conductivity, fluid conductivity) are determined.

porous electrode; multiscale modelling; effective properties; heat conduction

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