ENHANCEMENT OF CONVECTIVE HEATTRANSFER IN INTERNAL FLOWS USING ANELECTRICALLY-INDUCED CORONA JET

Reza Baghaei LakehPh.D. Candidate

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

CORONA DISCHARGE

Ionization of a neutral gas surrounding a conductor Strong electric field near a sharp electrode Ionization of neutral molecules

CORONA DISCHARGE

Ion generation mechanisms: α – process (electron impact ionization)α process (electron impact ionization)

γ – process (electron emission from cathode)

Field Emission (Electron Quantum Tunneling ) Field Emission (Electron Quantum Tunneling )

Electrons in a metal see a Electrons in a metal see a surface potential barrier due to the material’s work function.

For strong enough electric fields, the electrons can tunnel through the barrier tunnel through the barrier and materialize in the gap space.

Gomer, “Field Emission and Field Ionization,” 1961

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

CORONA WIND AND ION-DRAG FLOWS

Engineering point of view neglect “Sheath Layer”!I j ti f th i (O + d N + ) Injection of the ions (O2

+ and N2+ )

Dragging the neutral molecules and imposing a bulk flow referred as “Corona Wind” or “Ion-Drag” flow

CORONA WIND AND ION-DRAG FLOWS

Castellanos, “Electrohydrodynamics,” 1998

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

APPLICATIONS

Ion-Drag pumps

Heat Transfer Electrostatic Adamiak, 2004

Garimella, 2009

Transfer Enhancement

EHD Drag

R d i

Precipitators

EHD Thrusters

Reduction

Cooling

Lerner, 2000Go, 2010

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

BRIEF LITERATURE REVIEW

Pioneers: Velkoff (1963) and Moss (1966)

• Experimental Experimental • Circular Tube• Influence of Electric Field on the flow field and heat

transfer• Suggested Flow Field based on Heat Transfer

Augmentation:Augmentation:

S.M. Macro, H.R. Velkoff, Effect of Electrostatic, ASME Paper No. 63-HT-9, 1963R.A. Moss, J. Grey , Proceeding of Heat Transfer and Fluid Mechanics Institute, Santa Clara, CA , 1966

BRIEF LITERATURE REVIEW

Ohadi and Nelson (1987)

• Experimental • Circular tube• Noticeable heat transfer enhancement• Noticeable pressure dropNoticeable pressure drop

M.M. Ohadi, D.A. Nelson, S. Zia, International Journal of Heat and Mass Transfer, 1987

BRIEF LITERATURE REVIEW

Seyed-Yagoobi and Owsenek

• Experimental Numerical• Experimental, Numerical• EHD flow by electric conduction• Dielectric liquid refrigerants (Dissociation & Dielectric liquid refrigerants (Dissociation &

Recombination)• Heat Transfer enhancement in channels and ducts

B.L. Owsenek, J. Seyed-Yagoobi,, Journal of Heat Transfer, 1997

BRIEF LITERATURE REVIEW

Garimella (Cooling Technology Research Center)

• Experimental Numerical• Experimental, Numerical• Ion- Drag flows in micro-scale• Low voltage ionization (Quantum Tunneling)Low voltage ionization (Quantum Tunneling)• Enhancement of heat transfer in internal and external

flows

D.B. Go, S.V. Garimella, T.S. Fisher, IEEE 10th Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronics Systems, 2005

BRIEF LITERATURE REVIEW

Lai et al

• Experimental NumericalExperimental, Numerical• EHD gas pumps using needle-to-ring electrodes• Noticeable delivery of airflow y• Developed the EHD Drying mechanisms• Oscillatory flows

F.C. Lai, J. Mathew, Journal of Heat Transfer, 2007

BRIEF LITERATURE REVIEW

Molki et al.

• Experimental Numerical • Experimental, Numerical • Electrically-induced Secondary flow fields • Effect of corona discharge on natural convectionEffect of corona discharge on natural convection• Heat Transfer enhancement in channels with

rectangular, triangular and circular cross sections

M. Molki, K.L. Bhamidipati, International Journal of Heat and Mass Transfer, 2004

BRIEF LITERATURE REVIEW

Go and Balagopal (2011)

• ExperimentalExperimental• Localized Hot Spot Cooling• Wire-to-Rod• Counter-flow ionic wind and impingement-like effect• Cooling as much as 5K

Go and Balagopal, ESA Annual Meeting on Electrostatics, 2011

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

ION-DRAG FLOW IN CIRCULAR TUBES

Wire – tube Radial body force Navier – Stokes

ρEρuν

ρPu.u

tu c2

General view:

Wangnipparnto et al., Journal of Energy Conversion and Management, 2003

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

FORMULATION OF THE PROBLEM

Maxwell Equations in Electrohydrodynamics reduce to

Gauss’s Law

Maxwell–Faraday equation

Continuity Continuity

Magnetic field equations (rarely needed in Electrohydrodynamics)

FORMULATION OF THE PROBLEM

Electric Potential

Gauss’s Law

Conservation of electric charge

Ion mobility is the Electric current density Ion mobility is the dominant term of current density

y

Charge Convection Electric Conduction

Charge Diffusion

FORMULATION OF THE PROBLEM

B d C di i Boundary Conditions Electric Potential (Elliptic PDE)

V = Vo @ emitting electrode (Wire) V = 0 @ collecting electrode (Tube)

Charge Density (Hyperbolic PDE)Charge Density (Hyperbolic PDE) ρ = ρc,o @ emitting electrode ρc,o is found by measuring the time-average corona current

experimentally.p y

M. Molki, K.L. Bhamidipati, International Journal of Heat and Mass Transfer, 2004

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

ELECTRIC FIELD RESULTS+

Method of characteristics ++

Fluctuations i FVM in FVM Solution

Method of Characteristic Finite Volume Method

Baghaei Lakeh, R., Molki, M., ASME International Mechanical Engineering Congress & Exposition, 2009

FLOW FIELD RESULTS

Concentric configuration Hydrostatic condition Eccentric configuration

Secondary Flow Fi ldField

Recirculation Zones

Corona Jet

Baghaei Lakeh, R., Molki, M., Journal of Fluids Engineering, 2010

HEAT TRANSFER ENHANCEMENT

The corona-induced jet flow can significantly enhance the local heat transfer.

Hot Components

Temperature distributionMolki, M., Baghaei Lakeh, R., 63rd Annual Meeting of the American Physical Society, Division of Fluid Dynamics, 2010

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

PROPOSED RESEARCH

Ion-Drag flows in channels

Generating pumping effectHeat Transfer Enhancement

Disturbing the Boundary Layer Parallel Electric Force

Secondary Flows Fields

Direction of electric body-force in parallel configurationg

Corona Jet

PROPOSED RESEARCH

Corona Jet Circular Tube (eccentric wire

electrode)electrode)

Rectangular Channel with Rectangular Channel with longitudinal flat electrodes

PROPOSED RESEARCH

Methodology•Analytical (Method of Characteristics)•Computational (Finite Volume Method)

Electric Field

•Computational (Finite Volume Method)•Programming the code in C++•Experimental (Measurement of time-averaged corona current)

Flow ld

•Interpolating electric body-force between Electric Field and Flow Field grid points

•User-Defined-Function (UDF)•Commercial CFD Software ANSYS FLUENT 13Field •Commercial CFD Software, ANSYS FLUENT 13

Heat Transfer

•Temperature field•Heat Transfer Enhancement

PROPOSED RESEARCH

Extensive Grid Refinement Study according to Fluids Engineering Division of ASME.*g g

VerificationAnd

ValidationValidation

Comparison with i lifi d A l ti l

Comparison with il bl E i t l simplified Analytical

solutionsavailable Experimental

literature.

* Celik, I.B., Journal of Fluids Engineering, 2010

* Roache, P.J., Proceedings of Quantification of Uncertainty in Computational Fluid Dynamics, 1997

PROPOSED RESEARCH

Expected Results• Distributions of Electric field and Charge density :C g y

• Circular channels with centered wire electrode

• Rectangular channels with parallel longitudinal electrode arrays.y

• Secondary flow field on the cross section of the channels or along the channel axischannels or along the channel axis

• The effect of electric body-force on the buoyancy y y ydriven flows

PROPOSED RESEARCH

E t d R ltExpected Results•Distribution of temperature fields in various

configurations in rectangular and circular channels.

•The enhancement level of convective heat transfer using electrically-driven secondary flow fields in fully developed and developing regions of channels.

•Developing the targeted-cooling method by corona jets in circular and rectangular

igeometries.

PRESENTATION OUTLINEPRESENTATION OUTLINE

Corona Discharge Corona Wind and Ion-Drag Flows Applications

B i f Lit t R i Brief Literature Review Ion-Drag flow in Circular Tubes Formulation of the Problem Formulation of the Problem Preliminary Results Proposed Researchp Conclusion

CONCLUSION

Corona Discharge may lead to formation of Ion-Drag flows or Corona Discharge may lead to formation of Ion Drag flows or corona wind.

The electrically-induced secondary flow fields can be used for many applications including Heat Transfer Enhancement.

The ion-drag flows in some configurations lead to formation of a corona jet which may be used in different applications.

The proposed research studies the enhancement of heat transfer in internal flows and develops the idea of targeted spot cooling using a corona jet.p g g j

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