Steady state comparative-longitudinal heat flow method using specimen of different thicknesses for measuring thermal conductivity of lotus-type porous metals

Abstract

Lotus-type porous metal with many straight pores is attractive as a heat sink, because larger heat transfer capacity is obtained, owing to the small diameter of the pores. In order to use lotus-type porous metal effectively as a heat sink, it is important to clarify the effective conductivity and to consider the pore effect on heat conduction in the lotus-type porous metal. Because lotus-type porous metal is an anisotropic material, a steady state comparative-longitudinal heat flow (SCHF) method for thermal conductivity, referring to the ASTM standard, is thought to be better than a nonsteady method such as a laser flash method. This paper investigated the variable of the steady state comparative-longitudinal heat flow method by using specimens of different thicknesses (SCHF-DT) method for measuring the effective thermal conductivity. As a result, the uncertainty of effective thermal conductivity of a specimen was found to be smaller, as the diameter of a rod became larger and the length of a rod became shorter. In addition, it was found by error analysis that a dominant factor in the uncertainty of this method was the contact thermal difference between the rod and specimen.