Effect of Electric Field Distribution Generated in a Micro Space on Pool Boiling Heat Transfer

2013 ◽  
Author(s):  
Ichiro Kano ◽  
Kyohei Sato
Keyword(s):  
Electric Field ◽  
Traveling Wave ◽  
Boiling Heat Transfer ◽  
Electric Field Distribution ◽  
Pool Boiling ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
Uniform Electric Field ◽  
Working Fluid ◽  
Helmholtz Instability

This paper describes results from an experimental study of the effect of an electric field on nucleate boiling and the critical heat flux (CHF) in pool boiling. A dielectric liquid of AE-3000 (AGC Co. Ltd) was used as working fluid. A heating surface was polished with the surface roughness (Ra) of 0.05 μm. A micro sized electrode, in which the slits were provided, was designed in order to generate non uniform electric field and to produce electrohydrodynamic (EHD) effects with the application of high dc voltages. The obtained results confirmed the enhancement of CHF since the EHD effects increased the CHF to 82 W/cm2 at the voltage of −3000 V, which was four times greater than CHF for the pool boiling. The usual traveling wave on the bubble interface induced by the Kelvin-Helmholtz instability was modified by adding the EHD effects.

Effect of Electric Field Distribution Generated in a Microspace on Pool Boiling Heat Transfer

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Ichiro Kano
Keyword(s):  
Electric Field ◽  
Traveling Wave ◽  
Electric Field Distribution ◽  
Pool Boiling ◽  
Heating Surface ◽  
Wave Model ◽  
Nucleate Boiling ◽  
Working Fluid ◽  
Helmholtz Instability ◽  
Good Agreement

This study describes the effect of an electric field on nucleate boiling and critical heat flux (CHF) in pool boiling. A dielectric liquid of AE-3000 was used as the working fluid. A heating surface was polished to a surface roughness of 0.05 μm. A microsized electrode, in which slits were provided, was designed to generate a nonuniform electric field and produce electrohydrodynamic (EHD) effects with the application of high dc voltages. The obtained results confirmed CHF enhancement as the EHD effects increased CHF to 86.2 W/cm2 with a voltage of −3000 V, which was four times greater than pool boiling in the absence of the electrode. The usual traveling wave on the bubble interface, induced by the Kelvin–Helmholtz instability, was modified by adding the EHD effects. The traveling wave model exhibits the essential features of the phenomenon and shows good agreement with the experimental data.

Experimental Verification of Analytical Prediction of Pool Boiling CHF Incorporating the Effects of EHD and Contact Angle

2015 ◽  
Author(s):  
Ichiro Kano ◽  
Takahiro Sato ◽  
Naoki Okamoto
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Electric Field ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Contact Angles ◽  
Dielectric Liquid ◽  
Working Fluid ◽  
Analytical Prediction ◽  
Compound Effect

Boiling heat transfer enhancement via compound effect of Electro-Hydro-Dynamic (EHD) and contact angle has been experimentally and analytically investigated. A fluorinated dielectric liquid (Asahi Glass Co. Ltd, AE-3000) was selected as the working fluid. Pool boiling heat transfer in the saturated liquid was measured at atmospheric pressure. In order to change the contact angle between the boiling surface and the dielectric liquid, the different materials Cu, Cr, NiB, Sn, and mixture of 5 and 1.5 micro meter diamond particles were electrically deposited on a boiling surface. The critical heat flux (CHF) for different contact angles showed 20.5 ∼ 26.9 W/cm2 which was −7 ∼ 25 % of that for a non-coated Cu surface (21.5 W/cm2). Upon application of a −5 kV/mm electric field to the micro structured surface (the mixture of 5 and 1.5 micro meter particles), a CHF of 99 W/cm2 at a superheat of 33.5 K was obtained. The previous theoretical equation of pool boiling predicted the CHF with the electric field and without the electrode.

Analysis of the Polarity Influence on Nucleate Pool Boiling Under a DC Electric Field

1999 ◽  
Vol 121 (4) ◽  
pp. 856-864 ◽  
Author(s):  
M. C. Zaghdoudi ◽  
M. Lallemand
Keyword(s):  
Heat Transfer ◽  
Electric Field ◽  
Heat Transfer Enhancement ◽  
Field Distribution ◽  
Electric Field Distribution ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Transfer Enhancement ◽  
Field Polarity ◽  
The One

An experimental study of the action of an intense electric field on the pool boiling of n-pentane is presented. By the application of a 25 kV/cm electric field strength, a threefold heat transfer enhancement is obtained. The effect of the electric field polarity has been researched. In nucleate boiling, the negative polarity allows to obtain a heat transfer enhancement, which is better than the one obtained in positive polarity. However, in natural convection and near the critical heat flux, the polarity of the electric field has a low influence on the heat transfer. The interpretations of the observed results are based on the action of the electric field on the boiling phenomenon and more particularly on the analysis of the electric field distribution between the electrodes. The influence of the space charge injection and the effect of the temperature on the electric field distribution have been investigated. The results obtained in the two cases of polarity are discussed in terms of effects of electrical and thermal phenomena on the distribution of the electric field between the electrodes.

Experimental Study of Boiling Phenomena by Micro/Milli Hydrophobic Dot on the Silicon Surface in Pool Boiling

2009 ◽  
Author(s):  
Hang Jin Jo ◽  
Hyungmo Kim ◽  
Ho Seon Ahn ◽  
Seontae Kim ◽  
Soon Ho Kang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Silicon Surface ◽  
Room Temperature ◽  
Pool Boiling ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
Working Fluid

Many pool boiling experiments to enhance the nucleate boiling condition have been conducted and could get brilliant and challengeable results. A consensus was that CHF and heat transfer were affected by a modified heating surface. One of the efforts was the nanofluids experiments, and they have exhibited an incredible enhancement of CHF when nanofluids have been used as a working fluid in pool boiling. The results also have showed clearly that such large CHF enhancement came from the deposition of nanoparticles on the heating surface changing the surface condition. The surface covered by oxidized metal nanoparticles has a high wettability, and so it affects CHF. The fact that the wettability effect is significant to the enhancement of CHF is also supported by other kinds of boiling experiments. In addition, many researchers reported that wettability enhances not only CHF but also nucleate boiling heat transfer coefficient. In this regard, the excellent boiling performance (a high CHF and a high heat transfer coefficient) in pool boiling could be achieved through some favorable surface modification which satisfies the optimized wettability condition. For finding the optimized condition, we design the special heaters to examine how two materials, which have different wettabilities, affect the boiling phenomena. The special heaters have hydrophobic dots on the silicon surface. The hydrophobic dots lead to an early bubble inception. The bubble interface is bounded on the material boundary. The peculiar teflon(AF1600) is used as the hydrophobic material. The contact angle of the heating surface which is made by teflon is 120° to water at the room temperature. The contact angle of the silicon surface is 60° at the room temperature. The experiments using the micro hydrophobic dots and milli hydrophobic dot are performed, and the results are compared with the reference surface.

Ultrasonic augmentation in pool boiling heat transfer over external surfaces: A review

2020 ◽  
pp. 095440622095035
Author(s):  
Abhishek Swarnkar ◽  
Vikas J Lakhera
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
High Heat ◽  
Ultrasonic Field ◽  
Ultrasonic Waves ◽  
Heat Fluxes ◽  
Surface Topology

Boiling heat transfer is known for high heat fluxes at relatively small temperature differences. However, over the decades, technological innovations have demanded further augmentation in heat fluxes associated with boiling. Among the various active and passive methods, use of ultrasonic waves in boiling liquid has emerged as a proven technique for the required heat transfer improvement as demonstrated by a number of researchers. The present article reviews the application of ultrasonic waves in enhancing the heat transfer in various regimes of pool boiling. It has been found that the use of ultrasonic field is more promising in case of sub-cooled boiling as compared to saturated condition. Along with ultrasonic field of lower frequency and higher power, the usage of various passive techniques of surface improvement such as micro channel, surface topology, nano coatings etc. leads to further augmentation of heat transfer. Also, the relative placement of heating surface in ultrasonic wave field must be considered inevitably while designing an ultrasonic field assisted pool boiling system. It requires further investigations to conduct more parametric studies such as effect of pressure along with the usage of ultrasonic waves during sub- cooled boiling. Also during ultrasonic assisted pool boiling, various nano fluids can be tested for improving the heat transfer characteristics particularly in the saturated nucleate boiling regime.

Pool Boiling Heat Transfer From Artificial Micro-Cavities Surface in Dielectric Liquid FC-72

2004 ◽  
Author(s):  
C. K. Yu ◽  
D. C. Lu ◽  
T. C. Cheng ◽  
B. C. Tsai
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Working Fluid ◽  
Pronounced Increase ◽  
Pool Boiling Heat Transfer ◽  
Micro Cavity

Pool boiling heat transfer phenomenon of artificial micro-cavity enhanced surfaces by wet etching MEMS fabrication immersed in a saturated dielectric fluid has been experimentally studied. The present research is to investigate pool boiling behavior including heat transfer performance and flow pattern of “artificial micro cavities” heating surfaces simulating microelectronic devices at atmospheric pressure with FC-72 as the working fluid. The test surfaces are the solid silicon based blocks with 200 μm diameter circular cavities with flat plane, 16 × 16, 25 × 25, 33 × 33 array and 50 μm depth. Effects of this double enhancement technique on critical heat flux (CHF) and nucleate boiling heat transfer in the horizontal orientation (microcavities are vertical) were also investigated. Results indicated that, in general, increasing the number of micro cavities also increase the enhanced surface area and it could increase the critical heat flux. The pronounced increase of boiling heat transfer coefficients with the application of the artificial micro-cavity to the heat surface were also investigated in this paper.

Pool Boiling Enhancement by Electrohydrodynamic Force and Diamond Coated Surfaces

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Ichiro Kano
Keyword(s):  
Heat Transfer ◽  
Electric Field ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Cutting Tools ◽  
Diamond Particle ◽  
Working Fluid ◽  
Microstructured Surface ◽  
Microstructured Surfaces ◽  
Coated Surfaces

Boiling heat transfer enhancement via compound effect of the electrohydrodynamic (EHD) effect and microstructured surfaces has been experimentally and analytically investigated. A fluorinated dielectric liquid (Asahi Glass Co., Ltd., AE-3000) was selected as the working fluid. Pool boiling heat transfer in the saturated liquid was measured at atmospheric pressure. Microstructured surfaces, which are mainly used for cutting tools, were developed with diamond particles using electrodeposition technique. Four different particle diameters were prepared: 5, 10, 15, and a mixture of 5 and 1.5 μm. The critical heat flux (CHF) for diamond particle surfaces showed 27–30 W/cm2 which was 26–40% increase for comparing with a noncoated surface (21.5 W/cm2). Upon application of a −5 kV/mm electric field to the microstructured surface (a mixture of 5 and 1.5 μm particles), a CHF of 70.2 W/cm2 at a superheat of 21.7 K was obtained. The previous theoretical equation of pool boiling predicted the CHF with electric field and without the electrode within 10%. Also, the CHF enhanced by the diamond coated surfaces was correlated well with the contact angle.

Sign in / Sign up

Export Citation Format

Share Document