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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

PRE-HEATING EFFECT ON THE EXPANSION OF A BOILING BUBBLE ON A SMALL FILM HEATER HIGH PULSE POWERED

Get access (open in a dialog) DOI: 10.1615/IHTC13.p28.550
10 pages

Resumo

The pre-heating effect on the bubble expansion following spontaneous nucleation on a small film heater of high pulse power is investigated experimentally using ethyl alcohol as a test liquid. The pre-heating stage by a low-power pulse preceding the high-power pulse heating to cause spontaneous nucleation over the heater surface provides the significant storage of liquid superheat energy before boiling incipience. The growth configuration and the size of a single bubble formed by the coalescence of simultaneously nucleated bubbles are compared to the case without preheating. The bubble volume, which is estimated from top- and side-view photographs, increases significantly by the pre-heating and is well correlated with the liquid superheat energy at boiling incipience rather than the total pre-heating energy, regardless of the power or the period of the preheating. The bubble size (length, width and height) at maximum growth also correlated with the bubble volume, regardless of the pre-heating conditions.