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ISSN Online: 2377-424X

ISBN Print: 0-89116-299-2

International Heat Transfer Conference 7
September, 6-10, 1982, Munich, Germany

INVESTIGATION OF THE EFFECTS OF HEATER CHARACTERISTICS ON CHF PERFORMANCE OF A LONG VERTICAL ANNULUS IN HIGH PRESSURE WATER

Get access (open in a dialog) DOI: 10.1615/IHTC7.1120
pages 303-308

Resumo

CHF tests were performed in water on two identical annuli with 4.88 m heated length. The inner tube in one annulus was heated directly; the other was heated indirectly. These experiments were conducted at 9.7 MPa exit pressure over mass fluxes ranging from 2000 to 5000 kg/(s m2) and exit qualities of 14 to 28 per cent. One objective was to determine the effect of heating on CHF. A second and more important objective was to test the CHF predictive capabilities of multifluid models. The results show that the direct and indirect heaters have similar CHF characteristics in spite of the large difference in thermal heat capacitance. With regard to the multifluid model, CHF dryout was assumed to occur when the liquid film flow on the inner rod approached zero. CHF predictions were in good agreement with the experimental results. The main deviations were a trend toward under-prediction of CHF at low inlet subcoolings and over-prediction of CHF at high inlet subcoolings.