THE MINIMUM HEAT FLUX DURING FILM BOILING

1978 ◽  
Author(s):  
J. Berghmans
Keyword(s):  
Heat Flux ◽  
Film Boiling ◽  
Minimum Heat

On the Minimum Film Boiling Conditions for Spherical Geometries

1980 ◽  
Vol 102 (2) ◽  
pp. 335-341 ◽  
Author(s):  
F. S. Gunnerson ◽  
A. W. Cronenberg
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Flat Plate ◽  
Analytical Method ◽  
Boiling Point ◽  
Film Boiling ◽  
Heater Surface ◽  
Wide Range ◽  
Minimum Heat ◽  
Good Agreement

An analytical method is presented for predicting the minimum heater temperature and the minimum heat flux at the onset of film boiling for spherical and flat plate heaters in saturated and subcooled liquids. Consideration is given to a variety of factors known to affect the minimum film boiling point, including transient liquid-heater contact, interfacial wettability, heater geometry, and liquid subcooling. The theoretical correlations developed are the first known predictions for spherical geometries. A comparison of theory with experimental data indicates good agreement for the minimum heat flux and the minimum film boiling temperature. Results indicate that the minimum conditions may span a wide range depending upon the thermophysical nature of the heater surface and the boiling liquid.

The Dominant Unstable Wavelength and Minimum Heat Flux During Film Boiling on a Horizontal Cylinder

1964 ◽  
Vol 86 (2) ◽  
pp. 220-225 ◽  
Author(s):  
J. H. Lienhard ◽  
P. T. Y. Wong
Keyword(s):  
Surface Tension ◽  
Heat Flux ◽  
Flat Plate ◽  
Transverse Direction ◽  
Horizontal Cylinder ◽  
Heat Fluxes ◽  
Taylor Instability ◽  
Film Boiling ◽  
Minimum Heat ◽  
Effect Of Surface

Predictions of the dominant unstable wavelength and the minimum heat flux during film boiling above a flat plate are found to be inapplicable in the case of boiling on small wires. New expressions are developed for the case of a horizontal cylinder, by accounting for the effect of surface tension in the transverse direction upon the Taylor instability of the interface. Original measurements of wavelengths and minimum heat fluxes on small wires are also provided. These data support the predictions.

Effects of Gravity and Size Upon Film Boiling From Horizontal Cylinders

1970 ◽  
Vol 92 (2) ◽  
pp. 292-298 ◽  
Author(s):  
J. H. Lienhard ◽  
Kauo-Hwa Sun
Keyword(s):  
Heat Flux ◽  
Transition Point ◽  
Single Parameter ◽  
Film Boiling ◽  
Removal Mechanism ◽  
Low Gravity ◽  
Horizontal Cylinders ◽  
Minimum Heat

The vapor removal mechanism during film boiling on horizontal cylinders has been observed over an 81-fold variation of gravity and a tenfold variation of radius. These measurements are the basis for an assessment of prior predictions of wavelength. A significant low-gravity transition point in the vapor removal mechanism is identified and explained. “Best” formulas are recommended for the prediction of the wavelength and the minimum heat flux. These depend upon a single parameter which represents both size and gravity.

MHF (Minimum Heat Flux) Point on Anodized Zirconium Surface During Quenching

2014 ◽  
Author(s):  
Jun-young Kang ◽  
Seol Ha Kim ◽  
HangJin Jo ◽  
Ho Seon Ahn ◽  
Moo Hwan Kim ◽  
...  
Keyword(s):  
Heat Flux ◽  
High Speed ◽  
Visual Observation ◽  
Film Boiling ◽  
Temperature History ◽  
Complete Wetting ◽  
Wetting Contact Angle ◽  
History Of ◽  
Minimum Heat ◽  
Cylindrical Test

Quenching experiment for the evaluation of the Minimum Heat Flux (MHF) point on an anodized zirconium surface was conducted. The anodized zirconium surface showed complete wetting (Contact Angle, ∼ 0°) due to the capillary wicking force by nano- and micro-scaled structures in contrast to bare zirconium surface (∼ 54.3±2°). The cylindrical test sections (bare and anodized zirconium surface) heated up to 800 [°C] by radiation furnace was rapidly immersed into saturated distilled water. The temperature history of the test section showed the enhancement of the MHF point noticeably from 324 [°C] for the bare to 497 [°C] for the anodized zirconium surface. High speed visualization focusing on the interfacial dynamics at the film boiling showed stable wavy motion at the bare zirconium surface. On the contrary, vigorous fluctuation of the liquid-vapor interface on the anodized zirconium surface occurred. The visual observation suggested that it was caused by completely wetting features at the anodized zirconium surface. Therefore, it triggered the enhancement of the MHF point.

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