Transient Pool Boiling CHF in FC-72

2008 ◽  
Author(s):  
P. F. Sutopo ◽  
Katsuya Fukuda ◽  
Qiusheng Liu
Keyword(s):  
Pool Boiling ◽  
Heat Fluxes ◽  
Current Work ◽  
Film Boiling ◽  
Wide Range ◽  
Horizontal Cylinders

In the current work, critical heat fluxes (CHFs) and related boiling phenomena due to transient heat inputs, Q0exp(t/τ), to horizontal finite heaters were investigated in a pool of FC-72. Investigations were made on 1.0 mm diameter horizontal cylinders and a horizontal vertically oriented ribbon (4.0 mm × 0.1 mm × 31.5 mm) under a wide range of pressures ranged from 79.5 kPa up to 1278.1 kPa and liquid subcoolings ranged from saturated up to 140 K. The CHFs obtained from each heater with their dependency on pressure and liquid subcooling, and the typical ones against exponential period, τ, were observed and compared. The transition boiling processes to film boiling including mechanisms of incipient boiling and CHF, and vapor and bubble behaviors were also derived.

Transition Boiling Curves in Saturated Pool Boiling From Horizontal Cylinders

1996 ◽  
Vol 118 (3) ◽  
pp. 654-661 ◽  
Author(s):  
E. K. Ungar ◽  
R. Eichhorn
Keyword(s):  
High Speed ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Film Boiling ◽  
High Speed Flow ◽  
Wall Superheat ◽  
Speed Flow ◽  
Single Transition ◽  
Horizontal Cylinders

Pool boiling heat flux versus wall superheat boiling curves were obtained for horizontal 3.18-mm-dia thin-walled brass tubes heated by an internal high-speed flow of ethylene glycol. The boiling liquids were saturated n-pentane, R-113, acetone, methanol ethanol, benzene, and isopropanol. Boiling results include nucleate and transition boiling in all the test liquids, but film boiling was achieved only with methanol. The measured peak heat fluxes are well correlated by available predictions. The methanol experiments clearly display two transition boiling curves, one obtained on increasing the cylinder temperature from nucleate boiling, the other on decreasing the cylinder temperature from film boiling. For the cases in which the highest cylinder temperature reached only into the transition regime, a single transition boiling curve resulted.

Bubble Dynamics for Nucleate Pool Boiling of Electrolyte Solutions

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Seyed Ali Alavi Fazel ◽  
Seyed Baher Shafaee
Keyword(s):  
Experimental Data ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Close Relation ◽  
Electrolyte Solutions ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Nucleate Pool Boiling ◽  
Wide Range

Bubble dynamics is the most important subphenomenon, which basically affects the nucleate pool boiling heat transfer coefficient. Previous investigations state that the effect of physical properties of liquid and vapor phases on bubble departure diameter are often conflicting. In this article, extensive new experimental data are presented for the bubble departure diameter for various electrolyte aqueous solutions over a wide range of heat fluxes and concentrations. Experimental results show that the bubble detachment diameter increase with increasing either boiling heat flux or electrolyte concentration. Experimental results also present a close relation between the dimensionless capillary and bond numbers. A new model for the prediction of vapor bubble departure diameter in nucleate boiling for the electrolyte solutions is proposed, which predicts the experimental data with a satisfactory accuracy.

Dynamics of Pool Boiling on Plain and Nanotube Coated Silicon Surfaces

2010 ◽  
Author(s):  
Vijaykumar Sathyamurthi ◽  
Debjyoti Banerjee
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Chaotic Dynamics ◽  
Pool Boiling ◽  
Deterministic Chaos ◽  
Nucleate Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Film Boiling ◽  
Test Fluid

Saturated pool boiling experiments are conducted over silicon substrates with and without Multi-walled Carbon Nanotubes (MWCNT) with PF-5060 as the test fluid. Micro-fabricated thin film thermocouples located on the substrate acquire surface temperature fluctuation data at 1 kHz frequency. The high frequency surface temperature data is analyzed for the presence of chaotic dynamics. The shareware code, TISEAN© is used in analysis of the temperature time-series. Results show the presence of low-dimensional deterministic chaos, near Critical Heat Flux (CHF) and in some parts of the Fully Developed Nucleate Boiling (FDNB) regime. Some evidence of chaotic dynamics is also obtained for the film boiling regimes. Singular value decomposition is employed to generate pseudo-phase plots of the attractor. In contrast to previous studies involving multiple nucleation sites, the pseudo-phase plots show the presence of multi-fractal structure at high heat fluxes and in the film boiling regime. An estimate of invariant quantities such as correlation dimensions and Lyapunov exponents reveals the change in attractor geometry with heat flux levels. No significant impact of surface texturing is visible in terms of the invariant quantities.

Transient Pool Boiling Critical Heat Flux of FC-72 Under Saturated Conditions

2006 ◽  
Author(s):  
Sutopo P. Fitri ◽  
Katsuya Fukuda ◽  
Qiusheng Liu ◽  
Jongdoc Park
Keyword(s):  
Steady State ◽  
Hydrodynamic Instability ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Cylinder Surface ◽  
Empirical Correlations ◽  
Direct Transition ◽  
Spontaneous Nucleation ◽  
Horizontal Cylinders

In this study, the steady-state and transient critical heat fluxes (CHFs) in pool boiling were measured on 1.0 mm diameter horizontal cylinders of gold and platinum heaters under saturated conditions due to transient heat inputs, Q0exp(t/τ), in a pool of Fluorinert FC-72. Heaters were heated by electric current with the periods, τ, ranged from 10 ms to 20 s, and the pressures ranged from atmospheric up to around 1.2 MPa. The steady-state CHFs measured are dependent on pressure and almost agree with the values obtained by Kutateladze’s correlation based on hydrodynamic instability (HI) model. It was considered that the boiling inception and the direct transition during the steady-state period occur by the pre-pressure of ∼1.2 MPa. The trend of typical transient CHFs were clearly divided into the first, second, and third groups for long, short, and intermediate periods, respectively. The direct transition processes to film boiling without nucleate boiling for the short periods obtained from both heaters were confirmed due to the heterogeneous spontaneous nucleation (HSN) in flooded cavities on the cylinder surface. The empirical correlations to express each of corresponding CHFs measured on both heaters for the short periods are presented in this paper.

An Experimental Investigation of the Effects of Subcooling and Velocity on Boiling of Freon-113

1996 ◽  
Vol 118 (2) ◽  
pp. 436-441 ◽  
Author(s):  
L. Huang ◽  
L. C. Witte
Keyword(s):  
Weber Number ◽  
Large Scale ◽  
Heat Fluxes ◽  
Film Boiling ◽  
Electric Resistance ◽  
Stagnation Line ◽  
Maximum Heat ◽  
Fluid Velocities ◽  
Wide Range ◽  
Minimum Heat

Boiling heat transfer correlations were obtained for the maximum and minimum heat fluxes. Relationships among qmin/qmax, Weber number, and liquid Jakob number were obtained. Compelling evidence was found to indicate that significant cooling of the wake and/or the forward stagnation line can be caused by large-scale liquid–solid contacts while other parts of the surface experienced film boiling with little or no contact in the transition-film boiling regime. A criterion for large-scale liquid-solid contacts was developed. Another purpose of this study was to investigate whether a stable transition of boiling exists, i.e., if the ratio of the minimum and maximum heat fluxes approaches unity as liquid subcooling and velocity are increased. Extensive data using Freon-113 were taken, covering a wide range of fluid velocities (1.5 to 6.9 m/s) and liquid subcooling (29 to 100°C) at pressures ranging from 122 to 509 kPa. Cylindrical electric resistance heaters of two diameters, 6.35 mm and 4.29 mm, and made of Hastelloy-C and titanium, respectively, were used. The maximum qmin/qmax achievable with the apparatus was 0.9.

Film Boiling on Horizontal Cylinders in Helium II

1971 ◽  
Vol 93 (1) ◽  
pp. 11-18 ◽  
Author(s):  
R. M. Holdredge ◽  
P. W. McFadden
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Film Boiling ◽  
Experimental Measurements ◽  
Helium Ii ◽  
Horizontal Cylinders

The analysis of Rivers and McFadden for film boiling heat transfer from horizontal cylinders immersed in Helium II is briefly reviewed and results are recapitulated. Experimental measurements of film boiling heat transfer are made for horizontal cylinders of 0.145 cm and 0.245 cm dia immersed in Helium II baths at 1.78, 1.96, and 2.1 K at wall heat fluxes up to 2.84 w/cm2. The nondimensionalized experimental results are compared with the accepted correlations of Bromley and Breen and West-water to demonstrate the inability of the usual film boiling correlations to predict film boiling in Helium II. The nondimensionalized experimental results are compared with the predictions of the Rivers and McFadden analysis which considers Helium II properties, and the results of the analysis are substantiated.

Oxford Studies in Ancient Philosophy

2018 ◽  
Keyword(s):  
Political Philosophy ◽  
Middle Ages ◽  
Ancient Philosophy ◽  
Perceptual Content ◽  
Current Work ◽  
Ancient Greek ◽  
Original Essays ◽  
Wide Range ◽  
The Middle Ages

Oxford Studies in Ancient Philosophy provides, twice each year, a collection of the best current work in the field of ancient philosophy. Each volume features original essays that contribute to an understanding of a wide range of themes and problems in all periods of ancient Greek and Roman philosophy, from the beginnings to the threshold of the Middle Ages. From its first volume in 1983, OSAP has been a highly influential venue for work in the field, and has often featured essays of substantial length as well as critical essays on books of distinctive importance. Volume LIII contains: an article on several of Zeno of Elea’s paradoxes and the nihilist interpretation of Eudemus of Rhodes; an article on the coherence of Thrasymachus’ challenge in Plato’s Republic book 1; another on Plato’s treatment of perceptual content in the Theaetetus and the Phaedo; an article on why Aristotle thinks that hypotheses are material causes of conclusions, and another on why he denies shame is a virtue; and a book review of a new edition of a work possibly by Apuleius and Middle Platonist political philosophy.

Oxford Studies in Medieval Philosophy Volume 7

2019 ◽  
Keyword(s):  
Late Antiquity ◽  
Full Range ◽  
Current Work ◽  
Medieval Philosophy ◽  
Original Essays ◽  
Wide Range ◽  
Extended Review

Oxford Studies in Medieval Philosophy annually collects the best current work in the field of medieval philosophy. The various volumes print original essays, reviews, critical discussions, and editions of texts. The aim is to contribute to an understanding of the full range of themes and problems in all aspects of the field, from late antiquity into the Renaissance, and extending over the Jewish, Islamic, and Christian traditions. Volume 6 includes work on a wide range of topics, including Davlat Dadikhuda on Avicenna, Christopher Martin on Abelard’s ontology, Jeremy Skrzypek and Gloria Frost on Aquinas’s ontology, Jean‐Luc Solère on instrumental causality, Peter John Hartman on Durand of St.‐Pourçain, and Kamil Majcherek on Chatton’s rejection of final causality. The volume also includes an extended review of Thomas Williams of a new book on Aquinas’s ethics by Colleen McCluskey.

Pool Boiling Characteristics of Metallic Nanofluids

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
K. Hari Krishna ◽  
Harish Ganapathy ◽  
G. Sateesh ◽  
Sarit K. Das
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boiling Heat Transfer ◽  
Volume Fraction ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Solid Particles ◽  
Heater Surface ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Nanofluids, solid-liquid suspensions with solid particles of size of the order of few nanometers, have created interest in many researchers because of their enhancement in thermal conductivity and convective heat transfer characteristics. Many studies have been done on the pool boiling characteristics of nanofluids, most of which have been with nanofluids containing oxide nanoparticles owing to the ease in their preparation. Deterioration in boiling heat transfer was observed in some studies. Metallic nanofluids having metal nanoparticles, which are known for their good heat transfer characteristics in bulk regime, reported drastic enhancement in thermal conductivity. The present paper investigates into the pool boiling characteristics of metallic nanofluids, in particular of Cu-H2O nanofluids, on flat copper heater surface. The results indicate that at comparatively low heat fluxes, there is deterioration in boiling heat transfer with very low particle volume fraction of 0.01%, and it increases with volume fraction and shows enhancement with 0.1%. However, the behavior is the other way around at high heat fluxes. The enhancement at low heat fluxes is due to the fact that the effect of formation of thin sorption layer of nanoparticles on heater surface, which causes deterioration by trapping the nucleation sites, is overshadowed by the increase in microlayer evaporation, which is due to enhancement in thermal conductivity. Same trend has been observed with variation in the surface roughness of the heater as well.

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