INVESTIGATION OF LIQUID METAL BOILING HEAT TRANSFER
Analytical and experimental investigations were conducted on liquid metal boiling heat transfer. A study of saturated pool boiling of potassium in the nucleate regime supported the nucleate boiling data of Bonilla and coworkers at Columbia University. Values for the critical heat flux were determined experimentally over a pressure range of 0.1 to 22 psia. The data fall substantially above the theoretical predictions of Zuber and Tribus, Rohsenow and Kutateladze. The results are of the same magnitude as predicted by Noyes of Atomics international based on his experimental work with sodium at the lower end of this pressure range. The slope of the burnout flux versus pressure curve is much is much flatter than was predicted by Noyes on the basis of his data and a modified version of the hydrodynamic correlations.'' At atmospheric pressure the burnout flux was found to be approximately 600,000 Btu/ (hr)(sq ft). Significant temperature fluctuations were observed in the potassium pool during the course of these investigations. Superheating was attributed to the difficulty in establishing nucleating sites at the heat transfer surface in view of the strong wetting tendencies of the potassium and its high thermal diffusivity. The latter served to dissipate rapidly the energy required for nucleation in the boundary layer. Preliminary data in the stable film boiling regime have not yielded conclusive results. The studies to date have confirmed the superheating tendencies of alkali metal systems. Operation which was believed to have been in a stable film boiling regime produced fluxes much larger than predicted by analytical studies. Further data should be fonthcoming from this apparatus shortiy. The forced circulation studies have been plagued by a number of difficulties which have required substantial effort and time to resolve. Loop operation commenced in the spring of 1963, but was terminated shortly thereafter when persistent plugging difficulties in the primary potassium circuit prevented further operation. These difficulties were finally overcome during the summer months following the installation of a zirconium chip hot trap and potassium circulation has proceeded without difficulty since that time. An apparent break in the test section region has prevented the attainment of heat transfer results and has resulted in the contamination of the potassium circuit with sodium. The contamination was slight and it was possible to obtain two- phase pressure drop data and void fraction measurements with this apparatus. These results suggest that the Martinelli-Nelson correlation predicts pressure drops substantially lower than those observed experimentally at qualities up to 40%. Agravic studies with mercury have not produced data. The fabrication of the apparatus is nearing completion and initial check out procedures should begin shortiy. The program calls for the pool boiling of mercury at pressures up to 300 psia and accelerations up to 20 times that of normal gravity. The apparatus is capable of producing fluxes up to 500,000 Btu/ (hr) (sq ft). (auth)
- Research Organization:
- Michigan. Univ., Ann Arbor
- DOE Contract Number:
- AF33(616)-8277
- NSA Number:
- NSA-18-014033
- OSTI ID:
- 4080414
- Report Number(s):
- RTD-TDR-63-4130; AD-429182
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- United States
- Language:
- English
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INVESTIGATION OF LIQUID METAL BOILING HEAT TRANSFER. Quarterly Progress Report No. 3
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Related Subjects
ALKALI METALS
BOILING
BURNOUT
COOLANT LOOPS
DIAGRAMS
EQUATIONS
FABRICATION
FILMS
FLUID FLOW
GRAVITATION
HEAT TRANSFER
IMPURITIES
LAYERS
LIQUID METALS
MATHEMATICS
MEASURED VALUES
MERCURY
NUCLEATE BOILING
OPERATION
POTASSIUM
PRESSURE
SODIUM
STABILITY
SUPERHEATING
SURFACE TENSION
SURFACES
TEMPERATURE
TESTING
THERMAL DIFFUSION
TRAPS
VARIATIONS
ZIRCONIUM