Experimental and analytical study of the effects of wettability on nucleation site density during pool boiling

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7036441

Wang, Chunghsiung

Pool boiling of saturated water at one atmosphere pressure was investigated. A vertical copper surface was used and the surface was prepared by following a certain well-defined procedure. After preparation of the surface, the cumulative number density of the cavities and their shapes were determined. Wettability of the surface was changed by controlling the degree of oxidation of the surface. Wall heat flux and superheat were determined with the help of thermocouples embedded in the test block. A gamma ray densitometer was used to measure the void fraction in steady nucleate boiling experiments. The density, spatial distribution, local distribution, and nearest-neighbor distances distribution of active nucleation sites in partial and fully developed nucleate boiling were determined from still pictures. A theoretical model is proposed to describe the effect of wettability on nucleation site density. The theory successfully predicts active site densities with different contact angles and compares well with experimental data. By applying stationary vapor stem model, the theoretical boiling heat flux as a function of wall superheat is obtained results to compare well with experimental results.

• Research Organization: California Univ., Los Angeles, CA (United States)
• OSTI ID: 7036441
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
BOILING
CAVITATION
COPPER
ELEMENTS
HEAT FLUX
HYDROGEN COMPOUNDS
METALS
NUCLEATION
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
POOL BOILING
SURFACES
TRANSITION ELEMENTS
WATER