Measurement and analysis of effective thermal conductivities of lotus-type porous copper

Lotus-type porous copper is a porous medium made of copper that contains many straight pores. To effectively employ lotus-type porous copper as a heat sink, it is necessary to clarify the pore effect on the thermal conductivity of lotus copper. This article describes an experimental and analytical investigation on the effective thermal conductivities of lotus copper parallel and perpendicular to the pores. The lotus copper displayed anisotropy of the effective thermal conductivity. The effective thermal conductivity k(effperpendicular to) perpendicular to the pores was lower than that of the parallel ones k(effparallel to) and was 40% that of lotus copper material k(s) with porosity epsilon of 0.4. Experimental data for k(effparallel to) showed good agreement with analytical results derived from the assumption that heat flow through the cross-sectional area parallel to the pore axis is proportional to (1-epsilon). Experimental data for k(effperpendicular to) showed good agreement with the analytical results derived from the assumption of orthorhombic symmetry and with the numerical results under a uniform staggered array with a nonuniform pore diameter. (C) 2004 American Institute of Physics.