Surface Effects on Confinement-Driven Pool Boiling Enhancement in Vertical Parallel-Plate Channels

2005 ◽  
Author(s):  
Karl J. L. Geisler ◽  
Avram Bar-Cohen
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Boiling Heat Transfer ◽  
Parallel Plate ◽  
Nucleate Boiling ◽  
The Other ◽  
Transfer Enhancement ◽  
Channel Spacing ◽  
Boiling Enhancement ◽  
And Behavior

Evidence of confinement-driven boiling heat transfer enhancement in vertical channels is very well documented in the literature and much has been observed about its nature and behavior. However, the majority of the available correlations is empirically-based and they tend to be very restricted in their range of applicability and portability. In order to further elucidate the effect of this type of geometrical confinement on boiling heat transfer, an experimental study has been performed on vertical, rectangular parallel-plate channels immersed in the dielectric liquid FC-72. The enhancement of nucleate boiling performance with decreased channel spacing was found to depend on the type of heater employed but could not be explained by the surface roughness. On the other hand, degradation of the Critical Heat Flux (CHF) limit with decreasing channel spacing was found to be independent of the surface and to be well predicted by a correlation available in the literature.

Growth of Micro Bubbles on Micro-Configured Metal-Graphite Composite Surfaces and Boiling Enhancement

2008 ◽  
Author(s):  
David Chao ◽  
Nengli Zhang ◽  
Wen-Jie Yang
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Active Sites ◽  
Nucleate Boiling ◽  
Transfer Enhancement ◽  
Growth Processes ◽  
Graphite Composite ◽  
Boiling Enhancement ◽  
Structure Of Metal ◽  
Graphite Fibers

A series of studies in nucleate boiling phenomena on metal-graphite composite surfaces has been investigated by Prof. Wen-Jei Yang and their associates. It has been discovered that the unique micro-configured construction of the composite surfaces plays a crucial role in the enhancement of boiling heat transfer. The present paper focuses on the formation and growth processes of micro bubbles and the micro/nano scale boiling behavior to reveal the mechanism of boiling heat transfer enhancement on the unique surfaces. The growth processes of the micro and macro bubbles are analyzed and formulated followed by an analysis of bubble departure. Based on these analyses, the enhancement mechanism of the pool boiling heat transfer on the composite surfaces is clearly revealed. The micro-configured composite surfaces provide more even distribution of a great number of stable boiling active sites through the graphite fibers. Consequently, the heat conduction through the layers is increased, which provides the power of phase change at the interfaces on bubble bottoms. Experimental results convincingly demonstrate the enhancement effects of the unique structure of metal-graphite composite surfaces on boiling heat transfer.

scholarly journals Experimental study of nucleate boiling heat transfer enhancement by using surfactant

2011 ◽  
Vol 2 (3-4) ◽  
pp. 195-209 ◽  
Author(s):  
R.I. Elghanam ◽  
M.M.EL. Fawal ◽  
R. Abdel Aziz ◽  
M.H. Skr ◽  
A. Hamza Khalifa
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Enhancement ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Transfer Enhancement ◽  
Nucleate Boiling Heat Transfer

Effect of Heat Flux on Pool Boiling Heat Transfer Enhancement (Numerical Investigation Approach)

2020 ◽  
Author(s):  
T. S. Mogaji ◽  
O. A. Sogbesan ◽  
Tien-Chien Jen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Numerical Investigation ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Transfer Enhancement

Abstract This study presents numerical investigation results of heat flux effect on pool boiling heat transfer enhancement during nucleate boiling heat transfer of water. The simulation was performed for five different heated surfaces such as: brass, copper, mild steel, stainless steel and aluminum using ANSYS simulation software at 1 atmospheric pressure. The samples were heated in a domain developed for bubble growth during nucleate boiling process under the same operational condition of applied heat flux ranged from 100 to 1000 kW/m2 and their corresponding heat transfer coefficient was obtained numerically. Obtained experimental data of other authors from the open literature result is in close agreement with the simulated data, thus confirming the validity of the CFD simulation method used in this study. It is found that heat transfer coefficient increases with increasing heat flux. The results revealed that in comparison to other materials tested, better heat transfer performance up to 38.5% and 7.11% is observed for aluminum and brass at lower superheated temperature difference conditions of 6.96K and 14.01K respectively. This behavior indicates better bubble development and detachment capability of these heating surface materials and could be used in improving the performance of thermal devices toward producing compact and miniaturized equipment.

An Experimental Study of Transition and Film Boiling Heat Transfer in Liquid-Saturated Porous Bed

1986 ◽  
Vol 108 (1) ◽  
pp. 117-124 ◽  
Author(s):  
S. Fukusako ◽  
T. Komoriya ◽  
N. Seki
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Circular Cylinder ◽  
Boiling Heat Transfer ◽  
Heating Surface ◽  
Local Maximum ◽  
Nucleate Boiling ◽  
Film Boiling ◽  
Experimental Investigations ◽  
Porous Bed

Experimental investigations of transition and film boiling in a liquid-saturated porous bed are reported. The porous bed contained in a vertical circular cylinder is made up of packed spherical beads whose diameters range from 1.0 to 16.5 mm, while the depth of the bed overlying the heating surface varies from 10 to 300 mm. Water and fluorocarbon refrigerants R-11 and R-113 are adopted as testing liquids. Special attention is focused on the effect of the diameter of spherical beads on boiling heat transfer in the transition boiling region. It is found that for the small bead diameters the steady boiling heat transfer rises monotonically with temperature from nucleate boiling through the film boiling region, without going through a local maximum.

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