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International Heat Transfer Conference 12

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

Vapour Film Collapse Characteristics on Specimens Undergoing Forced Convection Film Boiling

Hussam I. Jouhara
Nuclear Engineering Research Group Manchester School of Engineering, University of Manchester, Manchester M13 5PL

Brian P. Axcell
Nuclear Engineering Research Group Manchester School of Engineering, University of Manchester, Manchester M13 5PL

DOI: 10.1615/IHTC12.1570
6 pages

Abstract

Forced convection film boiling has been studied experimentally using five different heated specimens and the transient cooling technique. The variation of specimen temperature with time was recorded and the heat flux, heat transfer coefficient and average film thickness were calculated, with particular interest in the values immediately prior to film breakdown. The characteristics of the vapour film collapse during the transients have been observed and recorded on video. The collapse mode depended largely on water subcooling. Three collapse modes have been identified: an explosive collapse at high subcoolings, a progressive collapse for low subcoolings, during which a quench front moved over the surface, and an explosive-progressive mode at intermediate subcoolings. With the latter mode, which had not been noted before the current investigation, the vapour film reformed briefly following an explosive generation of vapour at first contact between the hot surface and the liquid. Aquench front then moved progressively over the entire specimen surface.

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