Heat Transfer Enhancement Due to Electrically Induced Resonant Oscillation of Drops

1985 ◽  
Vol 107 (4) ◽  
pp. 788-793 ◽  
Author(s):  
N. Kaji ◽  
Y. H. Mori ◽  
Y. Tochitani
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Silicone Oil ◽  
Low Frequency ◽  
Transfer Enhancement ◽  
Resonant Oscillation ◽  
Second Mode ◽  
Shape Oscillation ◽  
Enhancing Heat Transfer ◽  
Water Drops

By applying a low-frequency alternating field with a specially designed waveform, we succeeded in making water drops in a medium of silicone oil undergo a resonant shape oscillation of the second mode. The resonant oscillation was found to be quite effective for enhancing heat transfer between the medium and drops.

Electrically Induced Shape Oscillation of Drops as a Means of Direct-Contact Heat Transfer Enhancement: Part 2—Heat Transfer

1988 ◽  
Vol 110 (3) ◽  
pp. 700-704 ◽  
Author(s):  
N. Kaji ◽  
Y. H. Mori ◽  
Y. Tochitani
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Electric Fields ◽  
Silicone Oil ◽  
Low Frequency ◽  
Transfer Enhancement ◽  
Contact Heat ◽  
Shape Oscillation ◽  
Sinusoidal Waveform ◽  
Water Drops

The heat transfer enhancement caused by the application of a low-frequency (1 ∼ 16 Hz) alternating field having the sinusoidal waveform has been studied experimentally with water drops in a medium of silicone oil. The heat transfer coefficient has been found to peak at three particular frequencies. The data newly obtained with the sinusoidal waveform are compared with earlier results obtained with electric fields having other waveforms. The waveform and the frequency that yield the largest enhancement of heat transfer are sought.

Flow and heat transfer enhancement in condensing water drops in steam flows

2014 ◽  
Vol 104 (7) ◽  
pp. 074101 ◽  
Author(s):  
Zhen Yang ◽  
Yuan-Yuan Duan ◽  
Zhao Zhu ◽  
Wei Gong ◽  
Xiao-Chen Ma ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Transfer Enhancement ◽  
Flow And Heat Transfer ◽  
Water Drops

Electrically Induced Shape Oscillation of Drops as a Means of Direct-Contact Heat Transfer Enhancement: Part 1—Drop Dynamics

1988 ◽  
Vol 110 (3) ◽  
pp. 695-699 ◽  
Author(s):  
N. Kaji ◽  
Y. H. Mori ◽  
Y. Tochitani
Keyword(s):  
Direct Contact ◽  
Low Frequency ◽  
Immiscible Liquid ◽  
Contact Heat ◽  
Resonant Oscillation ◽  
Liquid Drops ◽  
Contact Heat Exchange ◽  
Second Mode ◽  
Shape Oscillation ◽  
Sinusoidal Waveform

The shape oscillation of liquid drops passing through an immiscible liquid medium subject to a low-frequency (1 ∼ 16 Hz) alternating electric field having a sinusoidal waveform has been studied experimentally with the intention of investigating the enhancement of the direct-contact heat exchange between the two liquids. We have found that the field can induce, depending on its frequency, not only the resonant oscillation of the second mode of the drops, but also another peculiar oscillation that is related to the resonant oscillation of the third mode superposed on the second-mode oscillation.

Heat Transfer in Liquid-Liquid Taylor Flow in a Mini-Scale Tube With Constant Wall Temperature

2015 ◽  
Author(s):  
W. M. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Wall Temperature ◽  
Silicone Oil ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Flow Rates ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, heat transfer enhancement using liquid-liquid Taylor flow is examined. The experiments are conducted in mini-scale tubes with constant wall temperature. The segmented flow is created using several fractions of low viscosity silicone oil (1 cSt) and water for a wide range of flow rates and segment lengths. The variety of liquids and flow rates change the Prandtl, Reynolds, and capillary numbers. The dimensionless mean wall flux and the dimensionless thermal flow length are used to analyze the experimental heat transfer data. The comparison shows the heat transfer rate for Taylor flow is higher than in single-phase flow. The heat transfer enhancement occurs due to internal circulation in the fluid segments.

Enhancing Heat Transfer of Air-Cooled Heat Sinks Using Piezoelectrically-Driven Agitators and Synthetic Jets

2011 ◽  
Author(s):  
Youmin Yu ◽  
Terrence Simon ◽  
Min Zhang ◽  
Taiho Yeom ◽  
Mark North ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Single Channel ◽  
Synthetic Jets ◽  
Heat Sinks ◽  
Transfer Performance ◽  
Transfer Enhancement ◽  
Enhancing Heat Transfer

Air-cooled heat sinks prevail in microelectronics cooling due to their high reliability, low cost, and simplicity. But, their heat transfer performance must be enhanced if they are to compete for high-flux applications with liquid or phase-change cooling. Piezoelectrically-driven agitators and synthetic jets have been reported as good options in enhancing heat transfer of surfaces close to them. This study proposes that agitators and synthetic jets be integrated within air-cooled heat sinks to significantly raise heat transfer performance. A proposed integrated heat sink has been investigated experimentally and with CFD simulations in a single channel heat sink geometry with an agitator and two arrays of synthetic jets. The single channel unit is a precursor to a full scale, multichannel array. The agitator and the jet arrays are separately driven by three piezoelectric stacks at their individual resonant frequencies. The experiments show that the combination of the agitator and synthetic jets raises the heat transfer coefficient of the heat sink by 80%, compared with channel flow only. The 3D computations show similar enhancement and agree well with the experiments. The numerical simulations attribute the heat transfer enhancement to the additional air movement generated by the oscillatory motion of the agitator and the pulsating flow from the synthetic jets. The component studies reveal that the heat transfer enhancement by the agitator is significant on the fin side and base surfaces and the synthetic jets are most effective on the fin tips.

scholarly journals Effect of the distance between the micro/nanostructures on pool boiling heat transfer with water on a copper heater

2021 ◽  
Vol 2119 (1) ◽  
pp. 012081
Author(s):  
V Yu Vladimirov ◽  
S Ya Khmel
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Boiling Heat Transfer ◽  
Silicon Oxide ◽  
Pool Boiling ◽  
Copper Surface ◽  
Transfer Enhancement ◽  
Pool Boiling Heat Transfer ◽  
Enhancing Heat Transfer

Abstract Copper heaters were made. On the surface of these heaters the arrays of micrococoons were synthesized from silicon oxide (SiOx) nanowires with different concentrations of micro/nanostructures and hence different average distances between them. Boiling curves were obtained for these samples and it was found that heat transfer enhancement during boiling occurs on them in comparison with a smooth copper surface. It was shown that the effect increases with decreasing concentration of micro/nanostructures and reaches a maximum for microrelief with an approximate concentration of microstructures equal to unity per square micron. It was found that surfaces with micrococoons are sufficiently stable and suitable for enhancing heat transfer during boiling.

Melting Process Expedition of Phase Change Materials via Silicone Oil

2018 ◽  
Author(s):  
Sarvenaz Sobhansarbandi ◽  
Fatemeh Hassanipour
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Heat Transfer Enhancement ◽  
Phase Change Materials ◽  
Silicone Oil ◽  
Storage Systems ◽  
Ccd Camera ◽  
Melting Process ◽  
Operating Conditions ◽  
Transfer Enhancement

This paper presents a novel method of heat transfer enhancement and melting process expedition of phase change materials (PCMs) via silicone oil for the application in thermal energy storage systems. Sudden spot heating/cooling of the PCM causes a non-uniform melting process and in some cases the volume expansion/contraction. To avoid this malfunction, silicone oil can be applied in these systems to increase convective heat transfer (stirring effect). The feasibility of this method is investigated by two experimental analysis, one by having the mixture in a cylindrical container and one in a cubic container. The results from the images taken by Charge-Coupled Device (CCD) camera in the first analysis show a uniform melting process of the PCM. In the second analysis, the comparison is made for the two parallel setups with and without the silicone oil with the same operating conditions. The results show that in the system that lacks silicone oil, the paraffin starts melting after around 11 minutes from the heater start-up, while this time is around 6 minutes in the system with silicone oil. The effectiveness of silicone oil in enhancing the heat transfer rate is shown by a temperature rise of around 10 °C in the container. Applying PCMs in conjunction with silicone oil in various thermal storage systems for heating/cooling applications specifically in solar thermal collectors, enables heat transfer enhancement and consequently heat storage directly on the system.

Effect of Rib Width on the Heat Transfer Enhancement of a Rib-Turbulated Internal Cooling Channel

2009 ◽  
Author(s):  
A. P. Le ◽  
J. S. Kapat
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Reynolds Numbers ◽  
Internal Cooling ◽  
Transfer Enhancement ◽  
Cooling Channels ◽  
The Past ◽  
Rib Turbulators ◽  
Enhancing Heat Transfer ◽  
Straight Duct

In the quest for enhancing heat-transfer for the internal cooling channels of advanced turbo-machines, many schemes have been used and developed over the years. One such scheme is the use of rib turbulators. There have been fundamental studies in the past to understand the heat transfer enhancement phenomena caused by flow separation due to the presence of ribs. Typical ribs investigated in laboratory type experiments are square in nature i.e. the height, e, of the rib and the width, w, is the same. Although the literature deals with the effects of various rib shapes, little is known about the effect of having e/w not equal to unity. In this paper we investigate the degree of heat transfer enhancement caused by ribs with e/w not equal to unity. Experiments are carried out in a straight duct with ribs oriented normal to the main flow. The P/e ratio, P being the pitch of the ribs, is kept at a constant value of 10 while the ratio w/P is varied systematically from 0.1 to 0.5. Results are reported for Reynolds numbers ranging from 20,000 to 40,000. The aspect ratio of the channel is varied from 1:4 to 1:8 (Height : Width) and their effect is also shown. For all the cases investigated, pressure drop penalty is also presented.

Heat Transfer Enhancement in Spirally Corrugated Tube

2014 ◽  
Vol 7 (6) ◽  
pp. 970 ◽  
Author(s):  
Tholudin Mat Lazim ◽  
Zaid Sattar Kareem ◽  
M. N. Mohd Jaafar ◽  
Shahrir Abdullah ◽  
Ammar F. Abdulwahid
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Transfer Enhancement ◽  
Corrugated Tube
Sign in / Sign up

Export Citation Format

Share Document