HYDRODYNAMIC ASPECTS OF NUCLEATE POOL BOILING. PART I. THE REGION OF ISOLATED BUBBLES

Technical Report · Wed Jan 27 04:00:00 EST 1960

OSTI ID:4128751

Zuber, N

The theory of Bosnjakovic and Jakob (bubble growth is limited by the rate of heat transfer) is extended to predict the rate of vapor formation, in steady or transient boiling, with the assumption that the evaporation takes place at the base of the bubble. The predicted values are in satisfactory agreement with experimental results. An analytical expression, in terms of the bubble population, is derived for the velocity of the liquid adjacent to the heating surface. This velocity is used to estimate the heat transfer in nucleate boiling. Experimental data indicate that when bubbles can be considered as isolated, the heat transfer in nucleate boiling is intermittent and bears a similarity to the transfer of heat from a flat plate with boundary-layer formation. Experimental data indicate also that as the vapor void fraction (vapor hold-up) on the heating surface increases, a change occurs in the hydrodynamic conditions of the two- phase system. This change occurs at a heatflux density well below the critical heat flux. The vapor removal is altered from an intermittent to a continuous process. The mechanism of heat transfer is affected but not the process. An equation is derived for analyzing the relation which exists between the heat-flux density, the liquid-superheat temperature, and the bubble population in nucleate pool boiling. The predicted values are in qualitative and quantitative agreement with available experimental results. (auth)

• Research Organization: Ramo-Wooldridge. Div. of Thompson Ramo Wooldridge Inc., Canoga Park, Calif.
• NSA Number: NSA-14-025615
• OSTI ID: 4128751
• Report Number(s): TID-6338; RW-RL-164
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BOILING
BUBBLES
BURNOUT
DISTRIBUTION
ENGINEERING AND EQUIPMENT
EVAPORATION
FLUID FLOW
HEAT FLOW
HEAT TRANSFER
HEATING
HYDRAULICS
MATHEMATICS
MECHANICS
NUCLEATE BOILING
QUANTITATIVE ANALYSIS
QUANTITY RATIO
SUPERHEATING
SURFACES
TESTING
TRANSIENTS
VAPORS
VELOCITY
VOID FRACTION