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ISSN Online: 2377-424X

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

HEAT TRANSFER TO STEAM-WATER MIXTURES AT HIGH PRSSSURE - STUDIES OF BURNOUT IN ROUND TUBES

Get access (open in a dialog) DOI: 10.1615/IHTC3.90
pages 160-174

要約

Experiments are described in which "burnout" or "critical" heat flux has been determined for heat transfer to steam—water mixtures in uniformly heated round tubes at 1000 p.s.i.a. The tubes were 1/2 inch and 3/8 inch internal diameter and were heated over lengths ranging from 3 to 19 ft.
In the first series Of experiments, subcooled-water was introduced at the inlet to the tube and the steam phase generated within the test section. The maximum heated length used was somewhat greater than that which has been reported previously in the literature; the burnout power was found to increase markedly with heated length for high mass velocities but to change only a small amount with length at low mass velocities. The data were compared with four recent burnout correlations, all of which were found to perform, on average, about equally well. There were, however, regions in which particular correlations were found to be inadequate. The secondary variables of inlet throttling, tube wall thickness, and lagging were investigated and found to have little effect. Comparisons were also made with data obtained for nominally the same conditions with physically identical test sections on other equipment at A.E.E., Ninfrith; there appeared to be no great difference.
In the second series of experiments, steam was fed to the bottom of the tube and water was introduced around the tube periphery through a porous sinter. It was found that, in general, use of this type of mixed inlet gave somewhat higher burnout heat fluxes for a given exit quality than did the use of subcooled water at inlet. A minimum critical heat flux was observed at high qualities which corresponded to equality between the rate of droplet deposition and the rate of evaporation.