Thermal Resistance Measurement across a Wick Structure Using a Novel Thermosyphon Test Chamber

Abstract

A novel system is developed for measuring the thermal resistance across thin layers of sintered copper wicks of varying porosity. Wicks to be tested are integrated into a passive vertical thermosyphon system, and the resistance is measured for a series of input power levels. The wicks are sintered to a thermally conducting pedestal above a pool of deionized water and heated from below. The apparent thermal resistance across the wick (from the pedestal/wick interface to the vapor space) under the evaporative operating conditions encountered in heat pipes is measured using thermocouples. The apparent thermal resistance across the wick is measured to be as low as 0.01°C/W, corresponding to an evaporative heat transfer coefficient of greater than 128,000 W/m²K.

Keywords:

• heat pipe
• thermal resistance
• thermosyphon
• sintered copper wick

ACKNOWLEDGMENTS

The authors acknowledge financial support for this work from members of the Cooling Technologies Research Center (www.ecn.purdue.edu/CTRC), a National Science Foundation Industry/University Cooperative Research Center at Purdue University. Dr. Ioan Sauciuc and Dr. Hakan Erturk of Intel Corp. and Dr. Mark North of Thermacore Inc. are gratefully acknowledged for their assistance with fabrication of the experimental facility and for very useful technical discussions.