Design and test of carbon nanotube biwick structure for high-heat-flux phase change heat transfer

Qingjun Cai*, Chung-Lung Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


With the increase in power consumption in compact electronic devices, passive heat transfer cooling technologies with high-heat-flux characteristics are highly desired in microelectronic industries. Carbon nanotube (CNT) clusters have high thermal conductivity, nanopore size, and large porosity and can be used as wick structure in a heat pipe heatspreader to provide high capillary force for high-heat-flux thermal management. This paper reports investigations of high-heat-flux cooling of the CNT biwick structure, associated with the development of a reliable thermometer and high performance heater. The thermometer/heater is a 100-nm-thick and 600 μm wide Z-shaped platinum wire resistor, fabricated on a thermally oxidized silicon substrate of a CNT sample to heat a 2×2 mm2 wick area. As a heater, it provides a direct heating effect without a thermal interface and is capable of high-temperature operation over 800°C. As a thermometer, reliable temperature measurement is achieved by calibrating the resistance variation versus temperature after the annealing process is applied. The thermally oxidized layer on the silicon substrate is around 1-μm-thick and pinhole-free, which ensures the platinum thermometer/heater from the severe CNT growth environments without any electrical leakage. For high-heat-flux cooling, the CNT biwick structure is composed of 250 μm tall and 100 μm wide stripelike CNT clusters with 50 μm stripe-spacers. Using 1×1 cm2 CNT biwick samples, experiments are completed in both open and saturated environments. Experimental results demonstrate 600 W/cm2 heat transfer capacity and good thermal and mass transport characteristics in the nanolevel porous media.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalJournal of Heat Transfer
Issue number5
StatePublished - 1 May 2010


  • Carbon nanotube
  • Thermometer
  • Wick structure


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