Laminar to weakly turbulent mixed convection in a square duct heated from the bottom side is highly strengthened by ionic jets generated by an array of high voltage points, opposite to the heated strip. Negative ion injection is activated within the dielectric liquid HFE-7100. Local temperatures on the heated wall are measured by liquid crystal thermography. Distributions of the Nusselt number are obtained at different forced flow rates, applied heat flows, and transiting electrical currents. In correspondence of the point emitters, higher Nusselt numbers in the impingement areas are measured and an analogy with the thermo-fluid dynamic behavior of an array of submerged impinging jets in a crossflow is drawn. The diameter of the ionic jets is evaluated and an electrohydrodynamic Reynolds number is employed for correlation and similarity purposes. Potential applications of the technique are high-efficiency compact heat exchangers and heat sinks.
References
1.
Metais
, B.
, and Eckert
, E. R. G.
, 1964
, “Forced, Mixed, and Free Convection Regimes
,” ASME J. Heat Transfer
, 86
, pp. 295
–296
.10.1115/1.36871282.
Grassi
, W.
, and Testi
, D.
, 2006
, “Heat Transfer Correlations for Turbulent Mixed Convection in the Entrance Region of a Uniformly Heated Horizontal Tube
,” ASME J. Heat Transfer
, 128
(10
), pp. 1103
–1107
.10.1115/1.23454363.
Testi
, D.
, 2013
, “A Novel Correlation for Azimuthal and Longitudinal Distributions of Heat Transfer Coefficients in Developing Horizontal Pipe Flow Under Transitional Mixed Convection
,” Int. J. Heat Mass Transfer
, 60
, pp. 221
–229
.10.1016/j.ijheatmasstransfer.2013.01.0034.
Ohadi
, M. M.
, Darabi
, J.
, and Roget
, B.
, 2000
, “Electrode Design, Fabrication, and Material Science for EHD-Enhanced Heat and Mass Transport
,” Annu. Rev. Heat Transfer
, 11
, pp. 563
–632
.10.1615/AnnualRevHeatTransfer.v11.1105.
Grassi
, W.
, and Testi
, D.
, 2006
, “Heat Transfer Enhancement by Electric Fields in Several Heat Exchange Regimes
,” Ann. N. Y. Acad. Sci.
, 1077
, pp. 527
–569
.10.1196/annals.1362.0626.
Grassi
, W.
, Testi
, D.
, and Della Vista
, D.
, 2007
, “Optimal Working Fluid and Electrode Configuration for EHD-Enhanced Single-Phase Heat Transfer
,” J. Enhanced Heat Transfer
, 14
(2
), pp. 161
–173
.10.1615/JEnhHeatTransf.v14.i2.607.
Testi
, D.
, 2006
, “Single-Phase Thermo-Fluid Dynamics Under Electric Fields: Phenomenology and Technological Potential
,” Ph.D. thesis, Electrical and Thermal Energetics, University of Pisa, Pisa, Italy.8.
Spring
, S.
, Xing
, Y.
, and Weigand
, B.
, 2012
, “An Experimental and Numerical Study of Heat Transfer From Arrays of Impinging Jets With Surface Ribs
,” ASME J. Heat Transfer
, 134
, p. 082201
.10.1115/1.40061559.
Lamont
, J. A.
, Ekkad
, S. V.
, and Alvin
, M. A.
, 2012
, “Effects of Rotation on Heat Transfer for a Single Row Jet Impingement Array With Crossflow
,” ASME J. Heat Transfer
, 134
, p. 082202
.10.1115/1.400616710.
Ivanova
, E. M.
, Noll
, B. E.
, and Aigner
, M.
, 2013
, “A Numerical Study on the Turbulent Schmidt Numbers in a Jet in Crossflow
,” ASME J. Eng. Gas Turbines Power
, 135
, p. 011505
.10.1115/1.400737411.
Lacarelle
A.
, and Paschereit
, C. O.
, 2012
, “Increasing the Passive Scalar Mixing Quality of Jets in Crossflow With Fluidics Actuators
,” ASME J. Eng. Gas Turbines Power
, 134
, p. 021503
.10.1115/1.400437312.
Huber
, A. M.
, Viskanta
, R.
, 1994
, “Effect of Jet-Jet Spacing on Convective Heat Transfer to Confined, Impinging Arrays of Axisymmetric Air Jets
,” Int. J. Heat Mass Transfer
, 37
(18
), pp. 2859
–2869
.10.1016/0017-9310(94)90340-913.
Gao
, X.
, and Sundén
, B.
, 2003
, “Experimental Investigation of the Heat Transfer Characteristics of Confined Impinging Slot Jets
,” Exp. Heat Transfer
, 16
, pp. 1
–18
.14.
Siw
, S. C.
, Chyu
, M. K.
, Shih
, T. I.-P.
, and Alvin
, M. A.
, 2012
, “Effects of Pin Detached Space on Heat Transfer and Pin-Fin Arrays
,” ASME J. Heat Transfer
, 134
, p. 081902
.10.1115/1.400616615.
Kim
, S.
, Choi
, E. Y.
, and Kwak
, J. S.
, 2012
, “Effect of Channel Orientation on the Heat Transfer Coefficient in the Smooth and Dimpled Rotating Rectangular Channels
,” ASME J. Heat Transfer
, 134
, p. 064504
.10.1115/1.400601316.
Lamont
, J. A.
, Ekkad
, S. V.
, and Alvin
, M. A.
, 2012
, “Detailed Heat Transfer Measurements Inside Rotating Ribbed Channels Using the Transient Liquid Crystal Technique
,” ASME J. Thermal Sci. Eng. Appl.
, 4
, p. 011002
.10.1115/1.400560417.
Grassi
, W.
, Testi
, D.
, and Saputelli
, M.
, 2005
, “EHD Enhanced Heat Transfer in a Vertical Annulus
,” Int. Commun. Heat Mass Transfer
, 32
(6
), pp. 748
–757
.10.1016/j.icheatmasstransfer.2004.10.01118.
Grassi
, W.
, and Testi
, D.
, 2006
, “Heat Transfer Augmentation by Ion Injection in an Annular Duct
,” ASME J. Heat Transfer
, 128
(3
), pp. 283
–289
.10.1115/1.215083819.
Testi
, D.
, 2007
, “Ion Injection as an Effective Technique of Heat Transfer Enhancement in Space
,” AIAA J. Thermophys. Heat Transfer
, 21
(2
), pp. 431
–436
.10.2514/1.2497720.
Schanda
, J.
, 2007
, Colorimetry: Understanding the CIE System
, John Wiley & Sons
, Hoboken, NJ
.21.
Grassi
, W.
, Testi
, D.
, Della Vista
, D.
, and Torelli
, G.
, 2007
, “Calibration of a Sheet of Thermosensitive Liquid Crystals Viewed Non-Orthogonally
,” Measurement
, 40
(9–10
), pp. 898
–903
.10.1016/j.measurement.2006.10.02022.
Grassi
, W.
, and Testi
, D.
, 2011
, “Quantitative Measurements in Thermo-Fluid Dynamics Based on Colour Processing
,” Opt. Laser Technol.
, 43
(2
), pp. 381
–393
.10.1016/j.optlastec.2009.09.00723.
Bagnoli
, T.
, 2006
, “Application of a Thermographic Technique to the Study of Heat Transfer in a Square Duct in the Presence of EHD Phenomena
,” Graduate thesis, Aerospace Engineering, University of Pisa
, Pisa, Italy
.24.
Moffat
, R. J.
, 1988
, “Describing the Uncertainties in Experimental Results
,” Exp. Therm. Fluid Sci.
, 1
, pp. 3
–17
.10.1016/0894-1777(88)90043-X25.
Grassi
, W.
, and Testi
, D.
, 2009
, “Electrohydrodynamic Convective Heat Transfer in a Square Duct
,” Ann. N. Y. Acad. Sci.
, 1161
, pp. 452
–462
.10.1111/j.1749-6632.2008.04330.x26.
Geers
, L. F. G.
, 2003
, “Multiple Impinging Jet Arrays: An Experimental Study on Flow and Heat Transfer
,” Ph.D. thesis, Thermal and Fluids Sciences, Delft University of Technology
, Delft, The Netherlands
.27.
Findlay
, M. J.
, 1998
, Experimental and Computational Investigation of Inclined Jets in a Crossflow
, Ph.D. thesis, Mechanical Engineering, University of British Columbia
, Vancouver, Canada
.28.
Al-aqal
, O. M. A.
, 2003
, “Heat Transfer Distributions on the Walls of a Narrow Channel With Jet Impingement and Cross Flow
,” Ph.D. thesis, Mechanical Engineering, University of Pittsburgh
, Pittsburgh, PA.29.
Dano
, B. P. E.
, Liburdy
, J. A.
, and Kanokjaruvijit
, K.
, 2005
, “Flow Characteristics and Heat Transfer Performances of a Semi-Confined Impinging Array of Jets: Effect of Nozzle Geometry
,” Int. J. Heat Mass Transfer
, 48
(3–4
), pp. 691
–701
.10.1016/j.ijheatmasstransfer.2004.07.04630.
Kanokjaruvijit
, K.
, Martinez-Botas
, R. F.
, 2005
, “Jet Impingement on a Dimpled Surface With Different Crossflow Schemes
,” Int. J. Heat Mass Transfer
, 48
(1
), pp. 161
–170
.10.1016/j.ijheatmasstransfer.2004.08.00531.
Grassi
, W.
, Testi
, D.
, and Della Vista
, D.
, 2006
, “Heat Transfer Enhancement on the Upper Surface of a Horizontal Heated Plate in a Pool by Ion Injection From a Metallic Point
,” J. Electrost.
, 64
(7–9
), pp. 574
–580
.10.1016/j.elstat.2005.10.02532.
Crowley
, J. M.
, Wright
, G. S.
, and Chato
, J. C.
, 1990
, “Selecting a Working Fluid to Increase the Efficiency and Flow Rate of an EHD Pump
,” IEEE Trans. Ind. Appl.
, 26
(1
), pp. 42
–49
.10.1109/28.5267233.
Webb
, B. W.
, and Ma
, C.-F.
, 1995
, “Single-Phase Liquid Jet Impingement Heat Transfer
,” Adv. Heat Transfer
, 26
, pp. 105
–217
.10.1016/S0065-2717(08)70296-X34.
Kataoka
, K.
, 1990
, “Impingement Heat Transfer Augmentation Due to Large Scale Eddies
,” Proceedings of 9th International Heat Transfer Conference
, pp. 255
–273
.35.
Barata
, J. M. M.
, 1996
, “Fountain Flows Produced by Multiple Impinging Jets in a Crossflow
,” AIAA J.
, 34
(12
), pp. 2523
–2530
.10.2514/3.1343436.
Pan
, Y.
, Stevens
, J.
, and Webb
, B. W.
, 1992
, “Effect of Nozzle Configuration on Transport in the Stagnation Zone of Axisymmetric, Impinging Free-Surface Liquid Jets: Part 2—Local Heat Transfer
,” ASME J. Heat Transfer
, 114
, pp. 880
–886
.10.1115/1.2911896Copyright © 2013 by ASME
You do not currently have access to this content.
