Experimental study on performance of a miniature heat pipe with woven-wired wick

Abstract

The thermal density of electronic parts and systems has been increased continuously as high speed and high density are required for them. The heat generation of the CPU of a notebook PC of higher than the Pentium-II grade has been recently increased to be more than 10 W, and the available packaging space has been compacted. Therefore, it has become inevitable to perform cooling by using miniature heat pipes. In the present study, new woven-wired-type wick with a large capillary limit and a high productivity has been developed, and heat pipes with the diameter of 3 mm or 4 mm to cooling of small-sized electronic parts such as CPU of a notebook PC. Have been designed and manufactured. Further, in as much as the operational characteristics of miniature heat pipes (MHPs) with the diameter of 3 mm or 4 mm are different from those of general medium-sized heat pipes, a performance test has been performed in order to review heat-transfer characteristics and affects of various factors on the performance of MHPs. The operational factors include charging ratio of working fluid, the total length of heat pipes, lengths of an evaporator and a condenser, inclination of installation, number of wick strands, thermal load, etc. The limiting powers of 3 mm MHP and 4 mm MHP are shown to be 6.8 W and 19.5 W, respectively, with angle of inclination of -5/spl deg/. These show that there is a high possibility of application if one or two MHPs are installed for cooling of CPU more than 10 W.