Transition boiling heat transfer during reflooding transients

Journal Article · Sat Feb 01 04:00:00 EST 1986 · A.I.Ch.E. J.; (United States)

DOI:https://doi.org/10.1002/aic.690320229· OSTI ID:6077072

Weisman, J; Kao, Y K

Transition boiling heat transfer is characterized by a heat flux which declines as the heater wall temperature increases. Steady state transition boiling is also characterized by alternate periods of high and low heat transfer caused by intermittent wetting of the heated surface. In flow boiling, the reason for intermittent wetting depends on the volume fraction of vapor present. At high vapor volume fractions, annular flow exists during what is generally called the nucleate boiling region, and a thin liquid film is present on the surface. The remainder of the passage is filled with vapor carrying entrained droplets. Above the nucleate boiling region there is no liquid film, and heat is transferred to droplet-laden vapor. In the narrow transition boiling region between nucleate boiling and heat transfer to steam, the liquid film is present only part of the time. The intermittent wetting produces significant wall temperature oscillations. Recent phenomenologically based modeling of steady state transition boiling heat transfer at high vapor fractions has been successful in predicting the magnitude of both temperature oscillations and heat transfer rates. After a brief review of the steady state model, this note shows how the results of the steady state analysis for vertical surfaces may be used to obtain heat transfer rates during reflooding transients.

• Research Organization: Department of Chemical and Nuclear Engineering, University of Cincinnati, Cincinnati, OH 45221
• OSTI ID: 6077072
• Journal Information: A.I.Ch.E. J.; (United States), Journal Name: A.I.Ch.E. J.; (United States) Vol. 32:2; ISSN AICEA
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
BOILING
DROPLETS
ENERGY TRANSFER
FILMS
FLOW MODELS
FLUID MECHANICS
FLUIDS
GASES
HEAT FLUX
HEAT TRANSFER
HYDRAULICS
LOSS OF COOLANT
MATHEMATICAL MODELS
MECHANICS
NUCLEATE BOILING
PARTICLES
PHASE TRANSFORMATIONS
QUENCHING
REACTOR ACCIDENTS
REACTOR COMPONENTS
REACTOR CORES
STEADY-STATE CONDITIONS
TEMPERATURE EFFECTS
THIN FILMS
TRANSIENTS
VAPORS