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Research Papers

Thermal Management of Time-Varying High Heat Flux Electronic Devices

[+] Author and Article Information
T. David, D. Mendler, A. Mosyak

Department of Mechanical Engineering,
Technion—Israel Institute of Technology,
Haifa 32000, Israel

A. Bar-Cohen

Mechanical Engineering Department,
University of Maryland,
College Park, MD 20742

G. Hetsroni

Department of Mechanical Engineering,
Technion—Israel Institute of Technology,
Haifa 32000, Israel
e-mail: hetsroni@techunix.technion.ac.il

1Corresponding author.

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received July 4, 2013; final manuscript received March 27, 2014; published online April 29, 2014. Assoc. Editor: Gongnan Xie.

J. Electron. Packag 136(2), 021003 (Apr 29, 2014) (10 pages) Paper No: EP-13-1064; doi: 10.1115/1.4027325 History: Received July 04, 2013; Revised March 27, 2014

The thermal characteristics of a laboratory pin-fin microchannel heat sink were empirically obtained for heat flux, q″, in the range of 30–170 W/cm2, mass flux, m, in the range of 230–380 kg/m2 s, and an exit vapor quality, xout, from 0.2 to 0.75. Refrigerant R 134a (HFC-134a) was chosen as the working fluid. The heat sink was a pin-fin microchannel module installed in open flow loop. Deviation from the measured average temperatures was 1.5 °C at q = 30 W/cm2, and 2.0 °C at q = 170 W/cm2. These results indicate that use of pin-fin microchannel heat sink enables keeping an electronic device near uniform temperature under steady state and transient conditions. The heat transfer coefficient varied significantly with refrigerant quality and showed a peak at an exit vapor quality of 0.55 in all the experiments. At relatively low heat fluxes and vapor qualities, the heat transfer coefficient increased with vapor quality. At high heat fluxes and vapor qualities, the heat transfer coefficient decreased with vapor quality. A noteworthy feature of the present data is the larger magnitude of the transient heat transfer coefficients compared to values obtained under steady state conditions. The results of transient boiling were compared with those for steady state conditions. In contrast to the more common techniques, the low cost technique, based on open flow loop was developed to promote cooling using micropin fin sinks. Results of this experimental study may be used for designing the cooling high power laser and rocket-born electronic devices.

Copyright © 2014 by ASME
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References

Figures

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Fig. 1

Experimental facility: (1) reservoir, (2) valve, (3) gear pump, (4) pressure regulator, (5) Coriolis mass flow meter, (6) transparent tube, (7) temperature gauge, (8) throttle regular, and (9) test section

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Fig. 2

Adiabatic test section assembly

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Fig. 3

CFD simulation of pressure distribution across the microchannel

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Fig. 4

Heated test section assembly

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Fig. 5

Dimensions of pin-fin microchannel

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Fig. 6

Corresponding state points in a pressure-enthalpy diagram

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Fig. 7

Heater calibration

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Fig. 8

Dependence of the vapor quality at the outlet of test section on heat flux

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Fig. 9

Dependence of the heat transfer coefficient on heat flux

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Fig. 10

The heat transfer coefficient versus vapor quality at different values of mass flux

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Fig. 11

Time variation of heat flux: (a) m = 230 kg/m2 s and (b) m = 380 kg/m2 s

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Fig. 12

Time variation of heated wall temperature: (a) m = 230 kg/m2 s and (b) m = 380 kg/m2 s

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Fig. 13

Steady state temperature at the early stage of time-varying heat flux. q = 30 W/cm2 and m = 380 kg/m2 s.

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Fig. 14

Temporal temperature variations. Temperature field and histogram at fixed time instant of 10 s, and qmax = 170 W/cm2, m = 380 kg/m2 s.

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Fig. 15

Time variation of vapor quality at the outlet of text section: (a) m = 230 kg/m2 s and (b) m = 380 kg/m2 s

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Fig. 16

Variation of the heat transfer coefficient with vapor quality at the outlet of the test section

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