Impinged Droplet on High Temperature Heating Surface: Boiling Heat Transfer and Generation of Acoustic Sound

Nucleate pool boiling heat transfer experiments have been conducted to nanofluids on a horizontal cylinder tube under atmospheric pressure. The nanofluids are prepared by dispersing Al2O3 nanoparticles into distilled water at concentrations of 0.001, 0.01, 0.1, 1 and 2[Formula: see text]wt.% with or without sodium, 4-dodecylbenzenesulfonate (SDBS). The experimental results showed that: nanofluids at lower concentrations (0.001[Formula: see text]wt.% to 1[Formula: see text]wt.%) can obviously enhance the pool boiling heat transfer performance, but signs of deterioration can be observed at higher concentration (2[Formula: see text]wt.%). The presence of SDBS can obviously enhance the pool boiling heat transfer performance, and with the presence of SDBS, a maximum enhancement ratio of BHTC of 69.88%, and a maximum decrease ratio of super heat of 41.12% can be found in Group NS5 and NS4, respectively. The tube diameter and wall thickness of heating surface are the influential factors for boiling heat transfer coefficient. Besides, we find that Rohsenow formula failed to predict the characteristics of nanofluids. The mechanism study shows that: the decrease of surface tension, which leads to the decrease of bubble departure diameter, and the presence of agglomerates in nanofluids are the reasons for the enhanced pool boiling heat transfer performance. At higher concentration, particle deposition will lead to the decrease of distribution density of the vaporization core, and as a result of that, the boiling heat transfer performance will deteriorate.

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Pool boiling heat transfer in an upward horizontal rough heating surface.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.52.2998 ◽

1986 ◽

Vol 52 (480) ◽

pp. 2998-3002

Author(s):

Kinichi TORIKAI ◽

Kohoichi SUZUKI

Keyword(s):

Heat Transfer ◽

Boiling Heat Transfer ◽

Pool Boiling ◽

Heating Surface ◽

Pool Boiling Heat Transfer

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Visualization of Boiling Heat Transfer on Micro Porous Coated Surface in Confined Space

ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2013-73175 ◽

2013 ◽

Author(s):

Chien-Yuh Yang ◽

Chien-Fu Liu

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Boiling Heat Transfer ◽

Heat Transfer Performance ◽

Heating Surface ◽

Nucleate Boiling ◽

Confined Space ◽

Two Phase ◽

Nucleate Boiling Heat Transfer ◽

Coated Surface

Numerous researches have been developed for pool boiling on microporous coated surface in the past decade. The nucleate boiling heat transfer was found to be increased by up to 4.5 times than that on uncoated surface. Recently, the two-phase micro heat exchangers have been considered for high flux electronic devices cooling. The enhancement techniques for improving the nucleate boiling heat transfer performance in the micro heat exchangers have gotten more importance. Previous studies of microporous coatings, however, have been restricted to boiling in unconfined space. No studies have been made on the feasibility of using microporous coatings for enhancing boiling in confined spaces. This study provides an experimental observation of the vapor generation and leaving processes on microporous coatings surface in a 1-mm confined space. It would be helpful for understanding the mechanism of boiling heat transfer and improving the design of two-phase micro heat exchangers. Aluminum particles of average diameter 20 μm were mixed with a binder and a carrier to develop a 150 μm thickness boiling enhancement paint on a 3.0 cm by 3.0 cm copper heating surface. The heating surface was covered by a thin glass plate with a 1 mm spacer to form a 1 mm vertical narrow space for the test section. The boiling phenomenon was recorded by a high speed camera. In addition to the three boiling regimes observed by Bonjour and Lallemand [1], i.e., isolated deformed bubbles, coalesced bubbles and partial dryout at low, moderate and high heat fluxes respectively in unconfined space, a suction and blowing process was observed at the highest heat flux condition. Owing to the space confinement, liquid was sucked and vapor was expelled periodically during the bubble generation process. This mechanism significantly enhanced the boiling heat transfer performance in confined space.

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Can microorganisms survive high-temperature heating during the interplanetary transfer by meteorites?

BIOPHYSICS ◽

10.1134/s0006350907060176 ◽

2007 ◽

Vol 52 (6) ◽

pp. 640-644 ◽

Cited By ~ 2

Author(s):

A. K. Pavlov ◽

V. N. Shelegedin ◽

V. T. Kogan ◽

A. A. Pavlov ◽

M. A. Vdovina ◽

...

Keyword(s):

High Temperature ◽

Temperature Heating ◽

High Temperature Heating

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