Liquid Permeability of Ceramic Foam Filters
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This project is in support of the PhD project: Removal of Inclusions from Liquid Aluminium using Electromagnetically Modified Filtration . The purpose of this project was to measure the tortuosity, and permeability of ~50mm thick: 30, 40, 50 and 80 pores per inch (ppi) commercial alumina ceramic foam filters (CFFs). Measurements have been taken of: cell (pore), window and strut sizes, porosity, tortuosity and liquid permeability. Water velocity from ~0.015-0.77 m/s have been used to derive both first order (Darcy) and second order (Non-Darcy) terms for use with the Forchheimer equation. Experiments were made using 49 mm diameter straight through and 101 mm diameter expanding flow field designs. Experimental data are compared with simulation results made using COMSOL 4.2a® 2D axial symmetric finite element modelling (FEM). Permeability results are correlated using directly measurable parameters. Development of improved wall sealing (49 mm) and elimination of wall effects (101 mm), has lead to a high level of agreement between experimental, analytical and FEM methods (±0-7% on predicted pressure drop) for both types of experiments. The liquid permeability experiments were also used to determine the variability of permeability between different filters of the same ppi and permeability variation within the same CFF for changes position. Tortuosity has been determined by two inductive methods, one using cold solidified samples at 60 kHz and the other using liquid metal at 50 Hz, giving comparable results.