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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

HEAT FLUX CONTROLLED BOILING IN CONFINED SPACES

Get access (open in a dialog) DOI: 10.1615/IHTC13.p28.480
12 pages

Resumo

Recent interest in process intensification has resulted in many studies of boiling in confined spaces. Typically, these examine the relationships between heat flux, mass flux and quality similar in form to those widely accepted for use in conventional (>6 mm diameter) channels. As with large tubes, heat flux controlled, convective and dry out regions have been identified during boiling in confined spaces. The heat flux controlled region, often referred to as the apparently nucleate range, as indicated by the heat transfer being independent of quality, tends to be more marked in confined spaces than in conventional channels. In highly compact geometries, growth of confined bubbles controls the fluid flow and distribution at low to intermediate qualities. In this paper, from consideration of the growth of confined bubbles, it is shown that boiling heat transfer mechanisms in confined spaces are such that the mean heat transfer coefficient is a function of the rate of vapour generation, which in turn is directly proportional to the heat flux. Preliminary results from a study of boiling on a compact tube bundle are discussed and it is shown that the heat flux controlled region predominates in such a bundle.