INCIPIENT BOILING AND THE BUBBLE BOUNDARY LAYER FORMATION OVER A HEATED PLATE FOR FORCED CONVECTION FLOW IN A PRESSURIZED RECTANGULAR CHANNEL
The inception of bubbles for forced convection flow over a heated plate in a pressurized channel and their consequent mutual interaction in the formation of a bubble boundary layer was investigated. A high pressure closed loop was designed to permit visual observation of boiling over a heated plate and to provide temperature measurements of the boiling fluid. The plate, which is 0.50 in. wide and 9.48 in. long, was vertically oriented in a 0.50 x 0.46 in. rectangular channel. Photographs and temperature profile measurements were obtained for forced convection boiling of distilled water at pressures of 200 to 1000 psia, velocities of 1 to 6 ft/sec, subcoolings of 50 to 300 deg F and heat flux of 0.14 x 10/sup 6/to 1.5 x 10/sup 6/ Btu/hr-ft/sup 2/. A correlation equation for the incipient heat flux (the flux necessary to initiate observable bubbles) was obtained. The equation predicts incipient heat flux to within plus or minus 15%. The bubble boundary layer thickness was correlated to within plus or minus 20% by a dimensionless equation. Temperature profiles at various locations from the leading edge were measured. The mean temperature at the single-phase core-bubble boundary layer interface was found to approach inlet temperature as heat flux is increased toward its maximum value. Large temperature fluctuations were detected in both the single-phase core and the bubble boundary layer. The temperature fluctuations indicate the existence of subcooled liquid at the inlet temperature along the singlephase core-bubble boundary layer interface. It was also observed that the amplitude of temperature fluctuations near the heated surface decreases as the heat flux is increased. This suggests that burnout is characterized by the formation of a stagnant layer of superheated vapor near the surface.
- Research Organization:
- Univ. of Michigan, Ann Arbor
- NSA Number:
- NSA-16-033138
- OSTI ID:
- 4752526
- Journal Information:
- Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 23
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
BUBBLES
BURNOUT
CLEANING
CONVECTION
COOLING
DETECTION
DISTRIBUTION
EFFICIENCY
ENGINEERING AND EQUIPMENT
EQUATIONS
FILMS
FLUID FLOW
FORCED CONVECTION
HEATING
IMAGES
MEASURED VALUES
PHOTOGRAPHIC FILM
PIPES
PRESSURE
REACTION KINETICS
SUBCOOLING
SUPERHEATING
SURFACES
TEMPERATURE
THERMODYNAMICS
THICKNESS
VAPORS
VELOCITY
WATER
ZONES