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ISSN Online: 2377-424X

ISBN Print: 0-89116-909-1

International Heat Transfer Conference 9
August, 19-24, 1990 , Jerusalem, Israel

ON THE CHARACTERISTICS OF TRANSITIONAL PHENOMENA IN HEAT TRANSFER FROM EXTENDED SURFACES TO BOILING LIQUID

Get access (open in a dialog) DOI: 10.1615/IHTC9.1350
pages 87-92

Аннотация

Two modes of boiling heat transfer are known well, called nucleate and film boiling. There are two rapid transition of nucleate-film and film-nucleate boiling. In the same way, boiling heat transfer from an extended surface has two transitional phenomena moving back and forth between two boiling modes; the one is film, transition and nucleate boiling coexisting along the fin surface, and the other is fully developed film boiling. The time required for transition is fairly long comparing with an unfinned surface.
In this study the characteristics of this transitional phenomenon were discussed for three types of fin geometry, i.e., cylindrical, conical and annular fins, especially noticing the change of fin-tip temperature. The transition was largely affected by the heat capacity of fin tip. An annular fin showed sudden transition with large jump up or down of fin temperature as well as heat flux. On the other hand a conical fin had only slow and small jump, which is a favorite character to control. The effect of fin height, fin diameter and heat capacity of the heating block were also examined for cylindrical fins.