2014 Volume 22 Issue 4 Pages 85-95
As an application of a thermal management device for a high power microprocessor used in server computers, a loop heat pipe (LHP) containing a new design evaporator with a pin array conduction structure to enhance the evaporation area was developed. It was experimentally proven that the LHP can transfer a heat load of up to 360 W and that the thermal resistance of the LHP decreases to 0.138 °C ⁄ W in a heat load range of 295 to 334 W. The entire LHP is a flat structure in which the evaporator and a condenser are aligned in horizontal orientation. And the total height of the LHP is less than 40 mm, so it can be installed in a 1U (44.5 mm) server. The wick built into the evaporator consists of porous PTFE resin, and its mean pore radius of 10 um provides sufficient capillary pressure for continuous circulation of the working fluid around the LHP (with total piping length of 1.3 m). A cooling module using conventional heat pipes of the same shape as the LHP was fabricated and compared with the developed LHP in term of heat transfer characteristics over a distance of 200 mm. The comparison indicated that the LHP can stably transfer heat when it is subjected to three times or more power than that applied to a conventional heat pipes cooling module.
