EFFECT OF SURFACE TENSION ON LAMINAR FILM CONDENSATION ALONG A VERTICAL PLATE WITH A SMALL LEADING RADIUSShigeki Hirasawa DOI: 10.1615/IHTC6.170 摘要It was reported that a tube with many small sharp edge fins has a condensation heat transfer coefficient much higher than a tube without them. In this paper a theoretical investigation is made by introducing the surface tension term in fundamental equations as it is expected to play an important and essential part in laminar film condensation phenomenon near the sharp leading edge of a vertical flat plate providing both sides for the heat transfer surfaces. Numerical calculations by use of an iteration method by a computor are made to explain the high condensation heat transfer coefficient mentioned above. Results show that for a plate of a given height the heat transfer coefficient near the leading edge increases with a decrease of leading edge radius and there exists an optimum leading edge radius which makes the maximum condensation rate. The effect of heat transfer augmentation due to the edge radius decreases a little with decrease of the radius below this optimum radius and approaches a constant value. The effect of surface tension is less influenced by the temperature difference between the condensing surface and vapour and is found noticeable when the height of the plate is less than 5 mm for R113. 

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