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ISSN Online: 2377-424X

International Heat Transfer Conference 3
August, 7-12, 1966, Chicago, USA

TRANSIENT BOILING OF WATER AT ATMOSPHERIC PRESSURE

Get access (open in a dialog) DOI: 10.1615/IHTC3.1040
pages 186-192

Abstract

Rapid power transients in nuclear reactors raise the question of the mechanism of boiling when the heat flux into the water increases exponentially with time. There are reasons for expecting that this mechanism may change radically when the period of the exponential reaches about 1 m.sec, and experiments were made which extend the published information from periods of about 5 m.sec down to about 0.7 m.sec.

It is evident from the results that, even at the lowest periods tested, a short burst of nucleate boiling precedes film boiling; during this burst heat fluxes of several kilowatts per cm2 were measured. These heat fluxes exceed, by a factor of between 5 and 10, the "burnout" heat fluxes for steady pool boiling under similar conditions of sub-cooling. The "micro-layer vapourisation" mechanism proposed by Moore and Mesler could nevertheless reasonably explain the magnitude of the heat flux.