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ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

LOCAL HEAT TRANSFER COEFFICIENTS ON CONDENSATION IN A VERTICAL TUBE

Get access (open in a dialog) DOI: 10.1615/IHTC6.210
pages 437-342

Abstract

Local heat transfer measurements for film condensation of steam in cocurrent downflow inside a vertical copper tube 30/36 mm I/OD are reported. The Reynolds-number of the liquid film Ref was varied from 50 to 2000 and the ReG was varied from 7300 to 25400. It should be remarked that the Reynolds-numbers both for liquid and vapour flow Ref and ReG were varied independently. The experimental results indicate :
1. A distinctly laminar-turbulent transition Ref was not found.
2. In the Ref range below 150 the local Nusselt-number (Nux) exceed the prediction of the Nusselt theory for laminar film flow with interfacial shear by some 10-30 %.
3. The Nux-values in the middle Ref-range (150-800) are slightly sensitive to a Ref-variation and, they are substantially smaller than the Nux predicted according to Rohsenow or Dukler.
4. For Ref greater than 900 the Nux number is proportional to Ref04. That slope can be satisfactorily described by means of turbulence models with a wall and free interphase laws for the total viscosities.