Boiling on free-falling spheres; Drag and heat transfer coefficients

Journal Article · Mon Jan 01 00:00:00 EST 1990 · Experimental Heat Transfer; (USA)

DOI:https://doi.org/10.1080/08916159008946386· OSTI ID:6432900

Zvirin, Y ^[1]; Hewitt, G F ^[2]; Kenning, D B.R. ^[3]

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1. Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Mechanical Engineering
2. Imperial Coll. of Science and Technology, London (UK). Dept. of Chemical Engineering and Chemical Technology
3. Oxford Univ. (UK). Dept. of Engineering Science

Experiments have been conducted to measure drag (c{sub D}) and heat transfer coefficients (h) and to study the boiling nature on heated spheres free-falling in saturated and subcooled water. Simultaneous measurements of the transient sphere velocity and temperature during the fall enabled calculation of c{sub D}, heat fluxes, and h values. It has been found that the drag decreases with the initial sphere temperature, T{sub 0}. The measured results, as well as still and motion photography, show that at T{sub 0} {gt} 450{degrees}C film boiling prevails, with low heat fluxes at the beginning of the transient. In some cases the film collapses, leading to a transition to disturbed-film and micro-bubble regimes, associated with larger heat fluxes and also solid-liquid interactions, with lateral motion of the sphere (shoot-off).

• OSTI ID: 6432900
• Journal Information: Experimental Heat Transfer; (USA), Vol. 3:3; ISSN 0891-6152
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
WATER COOLED REACTORS
HEAT TRANSFER
DRAG
HEAT FLUX
INTERACTIONS
LIQUIDS
MEASURING METHODS
SOLIDS
ENERGY TRANSFER
FLUIDS
REACTORS
420400* - Engineering- Heat Transfer & Fluid Flow