An experimental study of dropwise condensation on horizontal condenser tubes

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Author
Manvel, John Talbot Jr.
Date
1979-06Advisor
Marto, P.J.
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Show full item recordAbstract
Three types of drop promoting coatings were applied to
the outside of 15.9 mm (5/8 in) outside-diameter condenser
tubes to determine their effect on heat transfer performance.
The coatings included a new fluoroepoxy, a commercial series
of fluorocarbon coatings, and sputtered TFE. Coating thickness
varied from 0.0 2 to 12.7 microns. Steam at about 21 KPa
(3 psia) was condensed on the outside surface of each coated
tube, horizontally mounted in the center of a dummy tube
bundle. Each test tube was cooled on the inside by water
at velocities of 0.80 to 7.60 m/sec (3 to 25 ft/sec).
The overall heat transfer coefficient was determined
directly from experimental data. The inside and outside,
heat transfer coefficients were determined by using the
Wilson Plot technique.
Of the commercial fluorocarbon coatings, the "Nedox"
coating on a copper-nickel tube enhanced the outside heat
transfer coefficient by 53% and improved the corrected
overall heat transfer coefficient by 27%. Of the sputtered
TFE coated tubes, the 0.08-micron thick coating on a copper-nickel
tube enhanced the outside heat transfer coefficient by
45% and improved the corrected overall heat transfer coefficient
by 21%. Evidence of the effect of the thermal conductivity
of the condensing surface substrate, and evidence of
an optimum coating thickness were found.
Rights
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.NPS Report Number
NPS 69-79-004Collections
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