Counter-current flow limitation in thin rectangular channels
The phenomenon of counter-current flow limitation (CCFL) in thin rectangular channels is important in determining the heat removal capability of research reactors which use plate-type fuel elements similar to the MTR design. An analytical expression for predicting CCFL in narrow rectangular channels was derived from the momentum equations for the liquid and gas phase. The model assumes that the liquid downflow is in the form of a film along the narrower side walls of the channel, while the gas flow occupies the wide span of the rectangular channel. The average thickness of liquid film is related to the rate of gas flow through a stability criterion for the liquid film. The CCFL correlation agrees with air/water data taken at relatively high gas velocities. Depending on the magnitude of the dimensionless channel width W{sup *}, the new CCFL correlation approaches zero liquid penetration either in the form of a Wallis correlation or in terms of a Kutateladze number. The new correlation indicates that for a thin rectangular channel, the constant C in the Wallis flooding correlation depends on the aspect ratio of the channel. The approach to the appropriate asymptotic solutions also justifies the use of twice the wide span as the correct length scale for thin rectangular channels. 14 refs., 6 figs.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6674560
- Report Number(s):
- BNL-44836; CONF-900917--14; ON: DE90015124
- Country of Publication:
- United States
- Language:
- English
Similar Records
Analytical study on mechanism of countercurrent flow limitation in vertical rectangular channels
Scaling ability of the counter-current flow limitation (CCFL) correlations for application to reactor thermal hydraulics
Related Subjects
22 GENERAL STUDIES OF NUCLEAR REACTORS
220600 -- Nuclear Reactor Technology-- Research
Test & Experimental Reactors
220900* -- Nuclear Reactor Technology-- Reactor Safety
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ACCIDENTS
COMPARATIVE EVALUATIONS
CORE FLOODING SYSTEMS
COUNTER CURRENT
COUNTERFLOW SYSTEMS
CRITICALITY
ECCS
ENERGY TRANSFER
ENGINEERED SAFETY SYSTEMS
FILMS
FLUID FLOW
FLUID MECHANICS
FORECASTING
GAS FLOW
HEAT TRANSFER
HYDRAULICS
INTERFACES
LIQUID FLOW
LOSS OF COOLANT
MATHEMATICAL MODELS
MECHANICS
REACTOR ACCIDENTS
REACTOR CHANNELS
REACTOR COMPONENTS
REACTOR PROTECTION SYSTEMS
REACTOR SAFETY
REACTORS
RESEARCH AND TEST REACTORS
SAFETY
SHEAR
STABILITY
TWO-PHASE FLOW
VELOCITY