Heat Transfrer Characteristics of Dropwise Condensation of Steam on a Vertical Bank of Horizontal Circular Tubes

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An objective of this study was to verify our prediction that, in the case of dropwise condensation, the heat transfer performance would not be deteriorated up to a certain number of rows, in a vertical bank of horizontal tubes. The heat transfer coefficient of film condensation decreases as the number of rows increases due to the effect of inundation. However, frequent sweing of the surface by drops falling from superior tubes are likely to enhance the heat transfer in the case of dropwise condensation, and would exceed the effect of inundation. Heat transfer measurements were carried out for both film and dropwise condensation of steam on the outside surface of a horizontal tube. The effect of the condensate dropping from the bank of tubes was simulated by regulating the flow rate of water draining onto the test tube from a perforated thbe placed just above.Conclusions obtained were:"(1) A bank of tube could be well simulated using a dripping tube, if it was designed and manufactured properly.(2) Heat transfer coefficient of dropwise condensation of steam on a bank of tubes did not deteriorate up to about tenth stage under the experimental condition employed in the present study.