THE EFFECTIVE THERMAL-CONDUCTIVITY OF POROUS MATERIAL WITH SPHERICAL INCLUSIONS IN A TETRAGONAL OR SIMPLE CUBIC ARRAY

The experimental and the numerical studies on the effective thermal co nductivity of porous material with spherical inclusions in a tetragona l or simple cubic array have been performed. Based on the unit cell mo del, an experimental device has been constructed to measure the effect ive thermal conductivity. Also, the numerical simulation based on the finite element method is adopted to calculate the present three-dimens ional heat conduction problem with the complex geometry. The compariso n between experimental and numerical results verify the availability o f unit cell model for porous materials. As the unit cell is in simple cubic array, the results are in good agreement with some existing mode ls predicted by Maxwell [5], Rayleigh [6], and Davis [10]. As to the u nit cell in tetragonal array, all the experimental and numerical resul ts show that the distance between the spheres in the direction of heat flow has a more significant effect on the effective thermal conductiv ity than other directions.