The Influence of External Electric Field on Heat Transfer at Boiling on Non-Uniform Surfaces

Characteristics of heat transfer and hydrodynamics of boiling of liquid nitrogen on the surfaces with different types of non-uniformities at the presence of external electric fields are experimentally investigated. It is shown that the formation of field traps is a major mechanism of heat transfer enhancement. And this effect result in noticeable change of two-phase hydrodynamics in vicinity of heated surface.

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Effect of Electric Fields on Two-Phase Impingement Heat Transfer

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 1 ◽

10.1115/ht2007-32863 ◽

2007 ◽

Author(s):

Xin Feng ◽

James E. Bryan

Keyword(s):

Heat Transfer ◽

Electric Fields ◽

Capillary Flow ◽

Heated Surface ◽

Heat Fluxes ◽

Working Fluid ◽

Geometrical Parameters ◽

Two Phase ◽

Transfer Rates ◽

Impingement Heat Transfer

The effect of electric fields applied to two-phase impingement heat transfer is explored for the first time. The application of an electric field between a capillary and heated surface results in the ability to control the free boundary flow from discreet drops to jets to sprays. Through an experimental study, the impingement heat transfer was evaluated over a range of operating and geometrical parameters using subcooled ethanol as the working fluid. The ability to change the mode of impinging mass did change the surface heat transfer. The characteristics of the impinging mass on heat transfer was dependent on capillary flow rate, applied voltage, capillary to heated surface spacing, capillary geometry, and heat flux. Enhancement occurred primarily at low heat fluxes (below 30 W/cm2) under ramified spray conditions where the droplet momentum promoted thin films on the heated surface. Higher heat fluxes resulted in greater vapor momentum from the surface minimizing the effect of different modes. However, under ramified spray conditions less mass was impacting the heated surface showing that heat transfer rates at higher heat fluxes were achievable with less mass, resulting in greater evaporation efficiency.

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A Review on Heat Transfer of Nanofluids by Applied Electric Field or Magnetic Field

Nanomaterials ◽

10.3390/nano10122386 ◽

2020 ◽

Vol 10 (12) ◽

pp. 2386

Author(s):

Guannan Wang ◽

Zhen Zhang ◽

Ruijin Wang ◽

Zefei Zhu

Keyword(s):

Magnetic Field ◽

Heat Transfer ◽

Electric Field ◽

Electric Fields ◽

Applied Electric Field ◽

Heat Transfer Performance ◽

Transfer Enhancement ◽

Heat Transfer Medium ◽

Conductivity Enhancement ◽

Chaotic Convection

Nanofluids are considered to be a next-generation heat transfer medium due to their excellent thermal performance. To investigate the effect of electric fields and magnetic fields on heat transfer of nanofluids, this paper analyzes the mechanism of thermal conductivity enhancement of nanofluids, the chaotic convection and the heat transfer enhancement of nanofluids in the presence of an applied electric field or magnetic field through the method of literature review. The studies we searched showed that applied electric field and magnetic field can significantly affect the heat transfer performance of nanofluids, although there are still many different opinions about the effect and mechanism of heat transfer. In a word, this review is supposed to be useful for the researchers who want to understand the research state of heat transfer of nanofluids.

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Numerical Study of EHD-Enhanced Forced Convection Using Two-Way Coupling

Journal of Heat Transfer ◽

10.1115/1.1578505 ◽

2003 ◽

Vol 125 (4) ◽

pp. 760-764 ◽

Cited By ~ 27

Author(s):

M. Huang ◽

F. C. Lai

Keyword(s):

Heat Transfer ◽

Electric Field ◽

Heat Transfer Enhancement ◽

Forced Convection ◽

Electric Fields ◽

Numerical Solutions ◽

Numerical Study ◽

Transfer Enhancement ◽

Wide Range ◽

The Difference

Numerical results are presented for heat transfer enhancement using electric field in forced convection in a horizontal channel. The main objective of the present study is to verify the assumption that is commonly used in the numerical study of this kind of problem, which assumes that the electric field can modify the flow field but not vice versa (i.e., the so-called one-way coupling). To this end, numerical solutions are obtained for a wide range of governing parameters (V0=10, 12.5, 15 and 17.5 kV as well as ui=0.0759 to 1.2144 m/s) using both one-way and two-way couplings. The results obtained, in terms of the flow, temperature, and electric fields as well as the heat transfer enhancement, are thoroughly examined. Since the difference in the results obtained by two approaches is insignificant, it is concluded that the assumption of one-way coupling is valid for the problem considered.

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Interactions Between Bubbles in Close Proximity Under Uniform and Non-Uniform Electric Fields

Volume 8: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A and B ◽

10.1115/imece2007-42762 ◽

2007 ◽

Author(s):

Matthew R. Pearson ◽

Jamal Seyed-Yagoobi

Keyword(s):

Heat Transfer ◽

Electric Field ◽

Heat Transfer Enhancement ◽

Electric Fields ◽

Nucleate Boiling ◽

Numerical Results ◽

Electrode Spacing ◽

Transfer Enhancement ◽

Close Proximity ◽

Multiple Bubbles

It is widely known that dielectrophoretic force can be harnessed to enhance the separation of liquid and vapor phases, with several known benefits in heat transfer enhancement. It has been shown that, when the electrode spacing and the bubble radius are of the same order of magnitude, the presence of the electric field can significantly deform the bubble, and this deformation can significantly affect the bubble’s behavior. Additionally, the presence of a bubble can provide significant, local distortion of the electric field. Consequently, the existence of multiple bubbles in close proximity may generate interactions that serve to further affect bubble deformation and motion behavior. Of course, nucleate boiling involves the generation of several bubbles in close proximity, and it is useful to understand whether these interactions may favorably or adversely affect the potential for heat transfer enhancement. This numerical study simulates the behavior of two and three bubbles within an external, electric field. The geometric deformation of the bubbles due to the electric field and the distortion of the electric field due to the existence of the bubbles are both incorporated into the mathematical model. The numerical results provide information about the effect that one bubble can have on the others’ motion, and also illustrate any tendencies of the bubbles to attract or repel each other when subject to various electric fields. Based on the numerical results, conclusions are drawn on the implications that the observed phenomenon may have on heat transfer enhancement applications.

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Mechanism of Annular Two-Phase Flow Heat Transfer Enhancement and Pressure Drop Penalty in the Presence of a Radial Electric Field—Turbulence Analysis

Journal of Heat Transfer ◽

10.1115/1.1571089 ◽

2003 ◽

Vol 125 (3) ◽

pp. 478-486 ◽

Cited By ~ 12

Author(s):

Y. Feng ◽

J. Seyed-Yagoobi

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Electric Field ◽

Heat Transfer Enhancement ◽

Annular Flow ◽

Radial Electric Field ◽

Phase Flow ◽

Transfer Enhancement ◽

Two Phase ◽

Flow Heat

The mechanism of heat transfer enhancement and pressure drop penalty in the presence of a radial electric field for the two-phase (liquid/vapor) annular flow is presented. The turbulence spectral theory shows that the radial electric field fluctuation changes the turbulent energy distribution, especially in the radial direction. Consequently, the Reynolds stresses are directly affected by the applied electric field. The analysis reveals that the influence of the applied electric field on the turbulence distribution in an annular two-phase flow leads to the changes in the heat transfer and the pressure drop. The magnitudes of the heat transfer enhancement and the pressure drop penalty are strongly related to the ratio of the radial pressure difference generated by the EHD force to the axial frictional pressure drop. The existing experimental data agree with the predictions of the analysis presented in this paper. The analysis developed here can be a valuable tool in properly predicting the two-phase annular flow heat transfer enhancement and pressure drop penalty in the presence of a radial electric field for both convective boiling and condensation processes.

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Numerical Study of EHD-Enhanced Forced Convection Using Two-Way Coupling

10.1115/imece2001/htd-24292 ◽

2001 ◽

Author(s):

M. Huang ◽

F. C. Lai

Keyword(s):

Heat Transfer ◽

Electric Field ◽

Heat Transfer Enhancement ◽

Forced Convection ◽

Electric Fields ◽

Numerical Solutions ◽

Numerical Study ◽

Transfer Enhancement ◽

Wide Range ◽

The One

Abstract In this paper, numerical results are presented for heat transfer enhancement using electric field in forced convection in a horizontal channel. The electric field is generated by charging a wire electrode located at the center of the channel with direct current at a high voltage. The main objective of the present study is to verify the assumption that is commonly used in the numerical study of this kind of problems, which assumes the electric field can modify the flow field but not vice versa (i.e., the so-called one-way coupling). To this end, numerical solutions have been obtained for a wide range of governing parameters (Vo = 10, 12.5, 15 and 17.5 kV as well as ui = 0.0759 to 1.2144 m/s) using both one-way and two-way couplings. Using the two-way coupling approach, the possible modification of the electric field by the primary flow, which was previously neglected, is accounted for. The results obtained using these two approaches, in terms of the flow, temperature, and electric fields as well as the heat transfer enhancement, are thoroughly examined. In addition, their influence over the flow stability is investigated. Finally, the conclusion about the validity of the one-way coupling is reached at the end of the study.

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