Prediction of the Operating Limits of Revolving Helically Grooved Heat Pipes

K. S. Klasing; S. K. Thomas; K. L. Yerkes

doi:10.1115/1.2825948

Operating Limits of Oscillating Heat Pipes

10.1615/ihtc12.2760 ◽

2002 ◽

Author(s):

Yoshiro Miyazaki ◽

Frantisek Polasek

Keyword(s):

Heat Pipes ◽

Operating Limits

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Transient Multidimensional Analysis of Nonconventional Heat Pipes With Uniform and Nonuniform Heat Distributions

Journal of Heat Transfer ◽

10.1115/1.2911233 ◽

1991 ◽

Vol 113 (4) ◽

pp. 995-1002 ◽

Cited By ~ 24

Author(s):

Y. Cao ◽

A. Faghri

Keyword(s):

Heat Pipe ◽

Three Dimensional ◽

Leading Edge ◽

Heat Pipes ◽

High Heat ◽

Heat Fluxes ◽

Multidimensional Analysis ◽

Vapor Flow ◽

Operating Limits ◽

Good Agreement

A numerical analysis of transient heat pipe performance including nonconventional heat pipes with nonuniform heat distributions is presented. A body-fitted grid system was applied to a three-dimensional wall and wick model, which was coupled with a transient compressible quasi-one-dimensional vapor flow model. The numerical results were first compared with experimental data from cylindrical heat pipes with good agreement. Numerical calculations were then made for a leading edge heat pipe with localized high heat fluxes. Performance characteristics different from conventional heat pipes are illustrated and some operating limits concerning heat pipe design are discussed.

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Thermodynamic Analysis of the Dryout Limit of Oscillating Heat Pipes

Energies ◽

10.3390/en13236346 ◽

2020 ◽

Vol 13 (23) ◽

pp. 6346

Author(s):

Florian Schwarz ◽

Vladimir Danov ◽

Alexander Lodermeyer ◽

Alexander Hensler ◽

Stefan Becker

Keyword(s):

Flow Pattern ◽

Annular Flow ◽

Analytical Data ◽

Heat Pipes ◽

Threshold Value ◽

Vapor Quality ◽

Cooling Systems ◽

Key Factor ◽

Operating Limits ◽

Experimental Approaches

The operating limits of oscillating heat pipes (OHP) are crucial for the optimal design of cooling systems. In particular, the dryout limit is a key factor in optimizing the functionality of an OHP. As shown in previous studies, experimental approaches to determine the dryout limit lead to contradictory results. This work proposes a compact theory to predict a dryout threshold that unifies the experimental and analytical data. The theory is based on the influence of vapor quality on the flow pattern. When the vapor quality exceeds a certain limit (x = 0.006), the flow pattern changes from slug flow to annular flow and the heat transfer decreases abruptly. The results indicate a uniform threshold value, which has been validated experimentally and by the literature. With that approach, it becomes possible to design an OHP with an optimized filling ratio and, hence, substantially improve its cooling abilities.

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Effects of Measurement Conditions on Operating Limits of Solar Horizontal Heat Pipes

Energy Procedia ◽

10.1016/j.egypro.2016.06.284 ◽

2016 ◽

Vol 91 ◽

pp. 366-375 ◽

Cited By ~ 1

Author(s):

Katharina Morawietz ◽

Tobias Röschl ◽

Ikhwan A. B. Abdul Halim ◽

Theresa Paul ◽

Michael Hermann

Keyword(s):

Heat Pipes ◽

Operating Limits

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A Parametric Investigation of Operating Limits in Heat Pipes Using Novel Metal Foams as Wicks

ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels: Parts A and B ◽

10.1115/fedsm-icnmm2010-31268 ◽

2010 ◽

Cited By ~ 6

Author(s):

Mahmood R. S. Shirazy ◽

Luc G. Fre´chette

Keyword(s):

Heat Transfer ◽

Metal Foam ◽

High Surface ◽

Heat Pipes ◽

Metal Foams ◽

Dimensionless Number ◽

Design Guideline ◽

Parametric Investigation ◽

Capillary Limit ◽

Operating Limits

A parametric investigation has been performed to study the different operating limits of heat pipes employing a novel type of metal foam as wick for chip cooling applications. These foams have a unique spherical pore cluster microstructure with very high surface to volume ratio compared to traditional metal foams and exhibit higher operating limits in preliminary tests of heat pipes, suggesting high cooling rates for microelectronics. In the first part of this parametric study, widely used correlations are applied to calculate the five types of heat transfer limits (capillary, boiling, viscous, entrainment and sonic) as a function of temperature, type of foam, and porosity. Results show that the dominant limit is mostly the capillary limit, but for 50 pore-per-inch (PPI) foam, the boiling limit will be dominant. Also, 50 and 60 PPI foams have higher heat transfer limits than sintered copper powder. In the second part of this study, thermodynamic steady state modeling of a flat heat pipe has been done to study the effect of the different parameters on the dominant limit (capillary). A dimensionless number has been proposed to evaluate the balance between the pressure loss in the vapor and liquid phases as an additional design guideline to improve the capillary limit in flat heat pipes.

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A Replica Technique for the Inside Surfaces of Small Diameter Pipes and Tubes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006177x ◽

1967 ◽

Vol 25 ◽

pp. 352-353

Author(s):

T. G. Gregory

Keyword(s):

Polyvinyl Chloride ◽

Small Diameter ◽

Replica Technique ◽

Tube Size ◽

Inside Diameter ◽

Complete Inspection ◽

Operating Limits

A nondestructive replica technique permitting complete inspection of bore surfaces having an inside diameter from 0.050 inch to 0.500 inch is described. Replicas are thermally formed on the outside surface of plastic tubing inflated in the bore of the sample being studied. This technique provides a new medium for inspection of bores that are too small or otherwise beyond the operating limits of conventional inspection methods.Bore replicas may be prepared by sliding a length of plastic tubing completely through the bore to be studied as shown in Figure 1. Polyvinyl chloride tubing suitable for this replica process is commercially available in sizes from 0.037- to 0.500-inch diameter. A tube size slightly smaller than the bore to be replicated should be used to facilitate insertion of the plastic replica blank into the bore.

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