Dryout stability and inception at low flowrates
A theoretical model for the heat flux required to maintain a stable hot patch on a heated surface cooled by a falling liquid film is developed. The dryout patch may be initially formed by hydrodynamic processes within the liquid film, but a higher heat flux is required to maintain the patch at an equilibrium size, neither growing or shrinking. The theoretical model is based on an analytical solution of the two-dimension heat equation with boundary conditions supplied by heat transfer coefficient correlations appropriate to the fluid conditions at the hot dry patch and at the wet region from the patch. The analytical results show that the heat flux required to maintain a dry patch is a function of only these correlations. This functional dependency has also been observed for the physically similar processes associated with quenching of an initially hot surface by a falling (or rising) liquid film. Using physically reasonable correlation forms for the dry patch and wet region heat transfer correlations, the heat flux is expressed as a function of the liquid film Reynolds number. The experimental data were obtained for liquid films falling on the outside of heated rods with heated lengths from 0.50 m to 3.66 m and heated diameters from 7.5 mm to 52.0 mm. The liquid film Reynolds number for the experimental data ranges from about 100 to about 10,000 and the heat flux ranges from about 1 kW/m{sup 2} to about 300 kW/m{sup 2}. 19 refs., 3 figs.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- DOE/NE
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 7166767
- Report Number(s):
- EGG-EAST-8491; ON: DE90006955
- Country of Publication:
- United States
- Language:
- English
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99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
HEAT FLUX
MATHEMATICAL MODELS
BOUNDARY CONDITIONS
COMPARATIVE EVALUATIONS
COOLING SYSTEMS
DATA PROCESSING
DESIGN
DIRAC EQUATION
EQUILIBRIUM
EVAPORATION
FLUID FLOW
HEAT TRANSFER
HYDRODYNAMICS
LAMINAR FLOW
NUSSELT NUMBER
STABILITY
THERMODYNAMICS
TURBULENT FLOW
TWO-DIMENSIONAL CALCULATIONS
VARIATIONS
VERIFICATION
DIFFERENTIAL EQUATIONS
ENERGY SYSTEMS
ENERGY TRANSFER
EQUATIONS
FLUID MECHANICS
MECHANICS
PARTIAL DIFFERENTIAL EQUATIONS
PHASE TRANSFORMATIONS
PROCESSING
WAVE EQUATIONS
420400* - Engineering- Heat Transfer & Fluid Flow
990200 - Mathematics & Computers