A novel micro counter-stream-mode oscillating-flow (COSMOS) heat-pipe

This paper presents, for the first time, a novel thin heat spreader based on COunter Stream Mode OScillating flow (COSMOS) concept. The heat spreader fabricated by silicon micromachining has 14 folded meander Si groove with total length of 700 mm, width of 575 /spl mu/m, depth of 400 /spl mu/m and the wall thickness between the adjacent channels of 150 /spl mu/m which is connected to two piezoelectric type pumps. The total device size was 86 /spl times/ 57 mm/sup 2/ and the effective cross-section of the heat-pipe was 0.5 /spl times/ 10 mm/sup 2/. The device demonstrated the temperature gradient of 500 K/m and the heat transport rate of 20 W with using water as working fluid. From these results, the effective thermal conductivity was calculated to 9/spl times/10/sup 3/ W/m/spl middot/K which is 23 times larger than that of copper.