Abstract
Up to now, there have been developed various applications of thermal micro pipes[1-3], such as refrigerating systems, high heat flux electronics cooling, and biological devices etc., based on vacuum vaporization followed by a convective phenomenon that allows vapor transfer from the vaporization area to the condensation one. This article presents studies carried out on the enhancement of the convective phenomenon taking place in flat thermal micro pipes. The proposed method[4] is aimed at the cooling of power electronics components, such as microprocessors. The conducted research focused on the use of shape memory materials that allow, by a semi-active method, to bring extra fluid in the vaporization area of the thermal micro pipe. The conducted investigations analyzed the variation of the liquid layer thickness in the trapezoidal micro channels and the thermal flow change over time. The modification of liquid flow was studied in correlation with the capacity of the polysynthetic material to retain the most extra fluid in its pores. The enhancement of the convective heat transfer phenomenon in flat thermal micro pipes was investigated in correspondence to the increase of liquid quantity in the vaporization zone. The charts obtained by aid of Mathcad[5] allowed to represent the evolution during a period of time (or with the pipe’s length) of the liquid film thickness, the flow and the thermal flow, as a function of the liquid supply variation due to the shape memory materials and the modification of the working temperature.
