Characterization of Ceramic Foam Filters Used for Liquid Metal Filtration

Abstract

In the current study, the morphology including tortuosity, and the permeability of 50-mm thick commercially available 30, 40, 50, and 80 pores per inch (PPI) alumina ceramic foam filters (CFFs) have been investigated. Measurements have been taken of cell (pore), window, and strut sizes, porosity, tortuosity, and liquid permeability. Water velocities from~0.015 to 0.77 m/s have been used to derive both first-order (Darcy) and second-order (Non-Darcy) terms for being used with the Forchheimer equation. Measurements were made using 49-mm ''straight through'' and 101-mm diameter ''expanding flow field'' designs. Results from the two designs are compared with calculations made using COMSOL 4.2a Ò 2D axial symmetric finite element modeling (FEM), as a function of velocity and filter PPI. Permeability results are correlated using directly measurable parameters and compared with the previously published results. Development of improved wall sealing (49 mm) and elimination of wall effects (101 mm) have led to a high level of agreement between experimental, analytic, and FEM methods (±0 to 7 pct on predicted pressure drop) for both types of experiments. 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.

A study on effects of ceramic foam filter on flow aspect through water modeling experiment

“…There are also some studies that investigate the characteristics and functions of ceramic foam filters. In these studies, the researchers tried to obtain generalized principles about the filter along with experimental measurement data [19][20][21][22] .…”

Effect of Fluid Bypassing on the Experimentally Obtained Darcy and Non-Darcy Permeability Parameters of Ceramic Foam Filters

“…In metallurgy, CFFs are used to remove undesired nonmetallic particles from molten metal before casting, [1,4,[7][8][9][10][11][12][13] i.e., filtration. In order to prime the filters, the melt has to reach a certain pressure on the top of the filter to initiate passage through the filter.…”

“…[9][10][11][12]14] To estimate, adjust, and maintain the required pressure and to regulate the melt velocity, it is essential to determine the Darcy and non-Darcy permeability coefficients of the filter. [8,9,15] The permeability coefficients can be obtained using permeametry experiments. [16][17][18] In general, permeametry is based on a gas or liquid flow through a porous media.…”

“…Thereafter, the Darcy and non-Darcy permeability coefficients k 1 (m 2 ) and k 2 (m) can be estimated using the Forchheimer equation for incompressible fluids (Eq. [1]), [2,8,9,15,17,[19][20][21] if the fluid dynamic viscosity l (Pa s) and fluid density q (kg/m…”

“…In the literature, [8,9,17,18,[22][23][24][25][26][27][28][29][30][31][32] it has been stated that accurate pressure drop estimates only can be achieved when fluid bypassing is avoided. If the CFF samples are not fully sealed, fluid will flow through the filter as well as the gap between the filter and filter holder.…”