Studies in boiling heat transfer in two phase flow through tube arrays: nucleate boiling heat transfer coefficient and maximum heat flux as a function of velocity and quality of Freon-113

Thesis/Dissertation · Sat Jan 01 00:00:00 EST 1983

OSTI ID:6024817

Rahmani, R

The nucleate boiling heat-transfer coefficient and the maximum heat flux were studied experimentally as functions of velocity, quality and heater diameter for single-phase flow, and two-phase flow of Freon-113 (trichlorotrifluorethane). Results show: (1) peak heat flux: over 300 measured peak heat flux data from two 0.875-in. and four 0.625-in.-diameter heaters indicated that: (a) for pool boiling, single-phase and two-phase forced convection boiling the only parameter (among hysteresis, rate of power increase, aging, presence and proximity of unheated rods) that has a statistically significant effect on the peak heat flux is the velocity. (b) In the velocity range (0 < U/sub infinity/ < 0.68 ft/sec) covered in this study the peak heat flux appears to exhibit a shallow minimum in the vicinity of U/sub infinity/ - 0.4 ft/sec. (c) The two-phase flow peak heat flux is 8 to 15% higher than the single-phase flow peak heat flux and the increase is independent of the quality of the flowing mixture. (d) For simultaneously heated elements at identical power inputs the excursion into film boiling always occurs at the most upstream heater regardless of the flow conditions. (2) Boiling pattern: single-phase forced convection drastically reduces the thickness of the two-phase zone surrounding the heater. (3) Local surface temperature: the coldest and the hottest spots of the heater are identified as the bottom (0/sup 0/ position or the point of impact of the incident fluid) and the top (180/sup 0/ position) of the test element, respectively.

• Research Organization: California Univ., Berkeley (USA)
• OSTI ID: 6024817
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

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FREONS
HEAT TRANSFER
TWO-PHASE FLOW
NUCLEATE BOILING
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EXPERIMENTAL DATA
TUBES
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HALOGENATED ALIPHATIC HYDROCARBONS
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NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHASE TRANSFORMATIONS
REACTORS
WATER COOLED REACTORS
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