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Research Papers

Steady and Unsteady Air Impingement Heat Transfer for Electronics Cooling Applications

[+] Author and Article Information
Mehmet Arik

Faculty of Engineering,
Department of Mechanical Engineering,
Ozyegin University Cekmekoy,
34782 Istanbul, Turkey
e-mail: mehmet.arik@ozyegin.edu.tr

Rajdeep Sharma

Exponent Inc.,
Menlo Park, CA 94025

Xin He

National Renewable Energy Laboratory,
Golden, CO 80401

Contributed by the Heat Transfer Division of ASME for publication in the Journal of Heat Transfer. Manuscript received April 25, 2012; final manuscript received December 22, 2012; published online September 23, 2013. Assoc. Sujoy Kumar Saha.

J. Heat Transfer 135(11), 111009 (Sep 23, 2013) (8 pages) Paper No: HT-12-1188; doi: 10.1115/1.4024614 History: Received April 25, 2012; Revised December 22, 2012

This paper focuses on two forced convection methods—steady jet flow and pulsating flow by synthetic jets—that can be used in applications requiring significant amounts of heat removal from electronics components. Given the dearth of available data, we have experimentally investigated steady jets and piezoelectrically driven synthetic jets that provide pulsating flow of air at a high coefficient of performance. To mimic a typical electronics component, a 25.4-mm × 25.4-mm vertical heated surface was used for heat removal. The impingement heat transfer, in the form of Nusselt number, is reported for both steady and unsteady jets over Reynolds numbers from 100 to 3000. The effect of jet-to-plate surface distance on the impingement heat transfer is also investigated. Our results show that synthetic jets can provide significantly higher cooling than steady jets in the Reynolds number range of 100 to 3000. We attribute the superior performance of synthetic jets to vortex shedding associated with the unsteady flow.

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References

Figures

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Fig. 4

Hot-wire probe positioned in front of the jet orifice (photo credit: Mr. Tunc Icoz GE GRC)

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Fig. 5

Variation of instantaneous jet exit velocities for 8 mm jet at 60 V and 600 Hz

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Fig. 3

Close up (oblique) view of synthetic jet and the vertical heater (photo credit: Mr. Sitki Ulcay)

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Fig. 2

Synthetic jet test setup (photo credit: Mr. Sitki Ulcay)

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Fig. 1

Typical operation of a synthetic jet; synthetic jets shown from top view

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Fig. 6

Schematic of the steady jet experimental setup. 1-compressed air, 2-desiccant dryer, 3-filter/regulator, 4-mass flow controller, 5-plate heat exchanger, 6-recirculating bath, 7-laminar flow element, 8-settling chamber, 9-nozzle, 10-heater target, 11-heater power supply, 12-isolation box

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Fig. 7

Steady jet experimental setup at NREL laboratory (photo credit: Jason A. Lustbader, NREL)

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Fig. 8

Comparison of synthetic jet experiments performed at GE GRC and NREL laboratories for the same jet

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Fig. 9

Nusselt number versus Reynolds number characteristic for synthetic and steady jet (S/Dh = 5)

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Fig. 10

Nusselt number versus Reynolds number characteristic for synthetic and steady jet (S/Dh = 10)

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Fig. 11

Nusselt number versus Reynolds number characteristic for synthetic and steady jet (S/Dh = 15)

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Fig. 12

Nusselt number versus Reynolds number characteristic for synthetic and steady jet (S/Dh = 20)

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Fig. 13

Nusselt number versus S/Dh for steady jet

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Fig. 14

Nusselt number versus S/Dh for synthetic jet

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