Further developments of filmwise condensation of steam on horizontal integral finned tubes
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Authors
Guttendorf, Mark Brady
Subjects
filmwise condensation
integral finned tubes
LMTD
integral finned tubes
LMTD
Advisors
Marto, Paul J.
Date of Issue
1990-06
Date
Publisher
Monterey, CA; Naval Postgraduate School
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Abstract
Heat transfer measurements have been made for filmwise condensation of steam on three families of horizontal integral finned copper tubes. The families differ from each other in their tube root diameter (12.7mm, 19.05mm, 25.00mm). The tubes making up each family differ from each other only in the fin spacing. Similar measurements have been carried out on three smooth horizontal copper tubes of outside diameters equal to the root diameters of each family, allowing the heat transfer enhancements due to the fins to be measured directly. Results carried out under vacuum and atmospheric conditions indicate that there is a optimum fin spacing which is independent of tube root diameter and operating pressure. This optimum fin spacing is 1.5mm. Heat transfer measurements were carried out on all tubes with and without the use of a spiral insert (used to enhance the internal heat transfer). It was found that with the current processing technique used, the heat transfer enhancement for a finned tube (which is based on the outside heat transfer coefficient) varies depending on whether or not an insert is used, the enhancement being lower when no insert is used. However, it was found that when testing a smooth tube there was no difference when an insert was or was not used. There is a need to develop a more accurate correlation for the inside heat-transfer coefficient. Further tests have been repeated using a finned tube geometrically similar to one being tested at the University of London. Discrepancies that existed between the two sets of data have been eliminated.
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Approved for public release; distribution is unlimited.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.