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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

HEAT TRANSFER PERFORMANCE OF WATER FLOW IN MICRO TUBES

Get access (open in a dialog) DOI: 10.1615/IHTC13.p14.140
10 pages

Sinopsis

This study provides an experimental investigation on forced convective heat transfer performance of water flowing through six micro tubes with inside diameters ranging from 0.123 to 0.962 mm. A non-contacted Liquid Crystal Thermography (LCT) temperature measurement method that proposed by Lin and Yang [2005] was used in this study to measure the surface temperature of micro tubes. The test results shows that, for all six tubes, the measured thermal developing and fully developed turbulent flow heat transfer coefficients agree very well with those predicted by conventional correlations. However, while the Reynolds numbers are greater than 1,000, the heat transfer coefficients increase with increasing Reynolds number. This is caused by that the tube length is not long enough for flow to be fully developed at high Reynolds number conditions and the flow is still in developing condition. The laminar-turbulent transition flow regime can be easily observed from the tube wall temperature variations. The wall temperature fluctuated within 0.2 °C during laminar and turbulent flow. But it fluctuated up to 2.3 °C while in transition regime. The transition occurs at Reynolds number from 2300 to 3000 and independent of size of the tubes. This is also the same range as that for conventional larger tubes. There is no size effect within the tested tube diameter range.