THEORETICAL STUDY ON HEAT TRANSFER PERFORMANCE OF DIRECTIOANLLY SOLIDIFIED POROUS COPPER HEAT SINK

Porous copper with long cylindrical pores fabricated by unidirectional solidification of metal-gas eutectic system can be used to manufacture a special kind of micro-channel heat sink. In order to simplify the heat transfer analysis, a fin model was introduced into the theoretical study on heat transfer performance of directionally solidified porous copper heat sink. The heat transfer performance of porous copper heat sink was also tested by experiments, and it was found that experimental values are far less than theoretical predicted ones. That is because the structure of porous copper might deviate from its ideal structure, such as, some pores are not penetrated, and the distribution of pore size and pore location is not uniform. After the model was modified by introducing area ratio of penetrating pores and mean diameter of penetrating pores, the theoretical results were consistent with the experimental results. Thus the analytical method based on the fin model in this paper can be used to predict the heat transfer performance of directionally solidified porous copper heat sink. According to the theoretical analysis, porous copper used for heat sink with excellent heat transfer performance should have the following porous structure: the pore diameter is 0.1-0.6 mm, the porosity is 30%-70%, the height of porous copper is more than 4 mm when its length along the direction of pore axis is 20 mm.