Filmwise Condensation of Steam on Externally-Finned Horizontal Tubes.
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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The film-condensation characteristics of a smooth tube and six externally-finned tubes having fins 1 mm high and 1 mm thick, and ptiches of 1.5, 2.0, 2.5, 3.0, 5.0, and 10.0 mm, were experimentally tested. A smooth copper tube with an active length of 133.5 mm, an outside diameter of 19.05 mm, and an inside diameter of 12.7 mm was first tested to correlate the inside heat-transfer coefficient using the Sieder-Tate equation. The leading coefficient for this equation was found to be 0.034 or - 0.001, and was used to derive the external condensing coefficient for all of the tubes by subtracting the inside and wall resistances from the measured overall resistance. The condensing coefficient was measured, both at atmospheric pressure and vacuum 84 mm hg, with the heat flux as a variable. Condensation data taken for the smooth tube were compared with data in the literature to check the reliability of the apparatus and the data-reduction procedures. The data for the finned tubes showed an optimum pitch of 2.5 mm. Author
- Marine Engineering