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First Thermal and Fluids Engineering Summer Conference

ISSN: 2379-1748
ISBN: 978-1-56700-430-4

EFFECTS OF SURFACE MODIFICATION USING CARBON NANOTUBES ON FLUID FLOW AND HEAT TRANSFER PERFORMANCE IN MICRO-CHANNEL HEAT SINK

DOI: 10.1615/TFESC1.mnt.012857
pages 1687-1692

Taha J. Taha
Thermal Engineering, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands

Theo H. Van der Meer
Department of Applied Physics, Delft University of Technology. Thermal Engineering, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands


KEY WORDS: CNTs, micro-channel, Heat transfer Augmentation

Abstract

An experimental heat transfer investigation was carried out to examine the influence of the carbon nanotubes (CNTs) layer deposits on convective heat transfer performance inside rectangular microchannels. Successful synthesis of vertically aligned CNTs was achieved using catalytic vapor deposition (CVD) process on silicon sample substrate. By varying the synthesis time, on average 6 pm and 20 pm thick layer of CNTs were made with surface roughness of (Sa=1.062 µm, Sq=1.333 µm) and (Sa=0.717 µm, Sq=0.954 µm) respectively. The external surface area of the samples increased 7 times compared to the bare silicon chip. The heat transfer performance of each sample was measured inside two rectangular microchannels with cross-section of 125 µm × 9 mm and 200 µm × 9 mm. For the 125 µm channel height, the 6 µm and 20 µm thick layer of CNTs resulted in 12% and 26% increase in friction factor respectively. Friction factors obtained from the 200 µm channel height show a similar trend with an increase of 6% and 16.4% for 6 µm and 20 µm CNTs layer thickness respectively. An average heat transfer enhancement of 19% and 74% is obtained inside the 125 µm height microchannel with 6 µm and 20 µm CNTs layer thickness respectively. Whereas, the average heat transfer enhancement of 22% and 62% are obtained inside the 200 µm channel with respective CNTs layer thicknesses of 6 µm and 20 µm. Enhancements are attributed to an increase in surface area and effective thermal conductivity inside the thermal boundary layer.

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