A Model for Fluid Flow During Saturated Boiling on a Horizontal Cylinder

1987 ◽  
Vol 109 (2) ◽  
pp. 485-490
Author(s):  
K. Kheyrandish ◽  
C. Dalton ◽  
J. H. Lienhard
Keyword(s):  
Heat Flux ◽  
Fluid Flow ◽  
Weber Number ◽  
Flow Boiling ◽  
Density Ratio ◽  
Horizontal Cylinder ◽  
Vapor Film ◽  
Vapor Density ◽  
Saturated Liquid ◽  
Saturated Boiling

A model has been developed to represent the vapor removal pattern in the vicinity of a cylinder during nucleate flow boiling across a horizontal cylinder. The model is based on a potential flow representation of the liquid and vapor regions and an estimate of the losses that should occur in the flow. Correlation of the losses shows a weak dependence on the Weber number and a slightly stronger dependence on the saturated liquid-to-vapor density ratio. The vapor jet thickness, which is crucial to the prediction of the burnout heat flux, and the shape of the vapor film are predicted. Both are verified by qualitative experimental observations.

Critical Heat Flux in Saturated Forced Convection Boiling on a Heated Disk With an Impinging Jet

1987 ◽  
Vol 109 (4) ◽  
pp. 991-996 ◽  
Author(s):  
M. Monde
Keyword(s):  
Heat Flux ◽  
High Pressure ◽  
Forced Convection ◽  
Critical Heat Flux ◽  
Weber Number ◽  
High Pressures ◽  
Density Ratio ◽  
Vapor Density ◽  
Heated Disk ◽  
Jet Velocity

Critical heat flux during forced convection boiling on an open heated disk being supplied with saturated liquids through a small round jet which impinges at the center of the disk has been studied experimentally employing refrigerant R12 at comparatively high pressures from 0.6 to 2.8 MPa. Generalized correlations, predicting the CHF within an experimental range of liquid-to-vapor density ratio 5.3–41.25 and the reciprocal of Weber number 2 × 10−3–2 × 10−7, are given for three different characteristic regimes: V-regime where the CHF increases with an increase in the jet velocity, I-regime where the CHF is nearly constant with jet velocity, and HP-regime where the CHF appears only at high pressure and again rises with an increase in the jet velocity.

A Study on Flow Boiling in Microchannel With Piranha Pin Fin

2015 ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Flow Boiling ◽  
Transfer Performance ◽  
Flow Conditions ◽  
Pin Fin ◽  
Flow And Heat Transfer

In this paper we reported an advanced structure, the Piranha Pin Fin (PPF), for microchannel flow boiling. Fluid flow and heat transfer performance were evaluated in detail with HFE7000 as working fluid. Surface temperature, pressure drop, heat transfer coefficient and critical heat flux (CHF) were experimentally obtained and discussed. Furthermore, microchannels with different PPF geometrical configurations were investigated. At the same time, tests for different flow conditions were conducted and analyzed. It turned out that microchannel with PPF can realize high-heat flux dissipation with reasonable pressure drop. Both flow conditions and PPF configuration played important roles for both fluid flow and heat transfer performance. This study provided useful reference for further PPF design in microchannel for flow boiling.

Effect of a Heat Flux Spike on the Downstream Dryout Behavior

1974 ◽  
Vol 96 (2) ◽  
pp. 121-125 ◽  
Author(s):  
D. C. Groeneveld
Keyword(s):  
Heat Flux ◽  
Density Ratio ◽  
Interfacial Instability ◽  
Force Balance ◽  
Vapor Density ◽  
Uniform Heating ◽  
Axial Conduction ◽  
Dry Patch ◽  
Wall Interaction ◽  
Patch Boundary

The effect of a short hot patch on the downstream dryout behavior was investigated in heated tubes cooled by Freon-12 at conditions equivalent (on the basis of liquid to vapor density ratio) to 69 bar in steam-water. The hot patch, located well upstream from the heated end, generated a heat flux spike which resulted in a local dry patch. Following an increase in downstream surface heat flux the dry patch would often spread in the downstream direction even though the heat flux was only a small fraction of the measured critical heat flux with uniform heating. A force balance on the dry patch boundary showed that, for certain conditions, spreading of the dry patch in the downstream direction is inevitable. This spreading however can be limited by interfacial instability, droplet-wall interaction and axial conduction.

Flow Film Boiling From a Sphere to Subcooled Freon-11

1986 ◽  
Vol 108 (4) ◽  
pp. 934-938 ◽  
Author(s):  
J. A. Orozco ◽  
L. C. Witte
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Velocity ◽  
Flow Boiling ◽  
Empirical Correlation ◽  
The Other ◽  
Film Boiling ◽  
Vapor Film ◽  
Peak Heat Flux ◽  
Semi Empirical

The boiling curves for flow boiling of freon-11 from a fluid-heated 3.81-cm-dia copper sphere showed dual maxima. One maximum corresponded to the nucleate peak heat flux while the other was caused by transitory behavior of the wake behind the sphere. Film boiling data were predicted well by the theory of Witte and Orozco. A semi-empirical correlation of the film boiling data accounting for both liquid velocity and subcooling predicted the heat transfer to within +/− 20 percent. The conditions at which the vapor film became unstable were also determined for various sub-coolings and velocities.

On the Prediction of the Minimum Pool Boiling Heat Flux

1980 ◽  
Vol 102 (3) ◽  
pp. 457-460 ◽  
Author(s):  
J. H. Lienhard ◽  
V. K. Dhir
Keyword(s):  
Heat Flux ◽  
Film Boiling ◽  
Vapor Film ◽  
Saturated Liquid ◽  
Flat Plates ◽  
Rate Of Increase ◽  
Constant Rate ◽  
Empirical Generalizations ◽  
Film Collapse ◽  
Minimum Heat

A criterion is offered for the collapse of film boiling in a saturated liquid at the minimum heat flux. The criterion says the vapor film collapse occurs when insufficient vapor is generated to sustain the growing wave after it reaches a constant rate of increase of amplitude. This criterion yields an accurate prediction for horizontal flat plates and cylinders. The prediction requires the use of empirical generalizations about the configuration of film boiling, which are also developed here.

SECOND‐GRADE FLUID FLOW WITH POWER‐LAW HEAT FLUX AND A HEAT SOURCE

2013 ◽  
Vol 44 (8) ◽  
pp. 687-702 ◽  
Author(s):  
Tasawar Hayat ◽  
Sabir A. Shehzad ◽  
Muhammad Qasim ◽  
F. Alsaadi ◽  
Ahmed Alsaedi
Keyword(s):  
Heat Flux ◽  
Fluid Flow ◽  
Heat Source ◽  
Power Law ◽  
Second Grade ◽  
Second Grade Fluid ◽  
Grade Fluid ◽  
Power Law Heat Flux
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