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Proceedings Paper

Microlayer Topology And Bubble Growth In Nucleate Boiling
Author(s): H. H. Jawurek; H. G. Macgregor; J. S. Bodenheimer
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Paper Abstract

During nucleate boiling thin liquid films (nicrolayers) form beneath the base of bubbles and evaporate into the bubble interiors. A technique is presented which permits the simultaneous determination of microlayer topology and the contribution of microlayer evaporation to bubble growth. Isolated-bubble boiling takes place on an electrically heated, transparent tin-oxide coating deposited on a glass plate, the latter forming the floor of a vessel. With coherent Claser) illumination from beneath, the microlayers reflect fringe patterns similar to Newton's rings. Owing to the rapid evaporation of the layers (the process is completed within milliseconds) the fringes are in rapid motion and are recorded by eine photography at some 4 000 frames per second and exposure times of 50 μs. The resulting interferograms provide details of microlayer shape and thickness versus time, and thus evaporation rate. Simultaneously, and on the same film, bubble profiles (and thus volumes) are obtained under white light illumination. The two bubble images are manipulated by mirrors and lenses so as to appear side by side on the same frame of film, the fringes magnified and the profiles reduced. Sample results for methanol boiling at a pressure of 58.5 kPa and with the liquid bulk at saturation temperature, are presented. Under such conditions microlayer evaporation accounts for 37 per cent of the total bubble volume at detachment.

Paper Details

Date Published: 1 September 1987
PDF: 13 pages
Proc. SPIE 0674, 17th Intl Congress on High Speed Photography and Photonics, (1 September 1987); doi: 10.1117/12.975554
Show Author Affiliations
H. H. Jawurek, University of the Witwatersrand (South Africa)
H. G. Macgregor, Witwatersrand (South Africa)
J. S. Bodenheimer, Hebrew University (Jerusalem)

Published in SPIE Proceedings Vol. 0674:
17th Intl Congress on High Speed Photography and Photonics
Donald Hollingworth; Maurice W. McDowell, Editor(s)

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