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Thermal Management Electronics Cooling

Paper By:

1. Prof. Kiran D. Devade (Lecturer, Mech Dept.)

2. Prof. Avinash M. Patil (Professor, Mech Dept.)

3. Prof. Sunil B. Ingole (Assistant Professor, Mech Dept)

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Thermal Management

1. Introduction

2. Need3. Methods Available

4. Research Work

5. Future Prospective

6. Conclusion

The Paper deals With,

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Introduction

• Electronics is

developing field, since

long through decades itis moving towards

miniaturization in size 

and maximizing

capacities.

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History

• This was the CPU of a

computer before 

introduction of

microprocessors

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PAST

• After microprocessors

computers becamemore smaller and

cheaper

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Now,

• But with advancements

the computers are

becoming more

compact and morecheaper

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The graph indicates the relation of size vs  computing ability of a chip it is increasing

exponentially.

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Old 

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Latest

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Why Electronic Cooling

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Other Source of heat generation

Due to the advantages of high local heat and mass transferrate and a relatively easy control of areas to be cooledor heated, impinging jets are widely used in manyindustrial applications such as,

•  cooling of hot steel plates.• annealing of glass and sheet metals.

•  drying of papers, films , textiles.

• cooling of turbine blades.

•  electronic components.•  most recently manufacturing of TFT-LCD plate.

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Methods for cooling- forced convection

Various cooling options that are available till date are:

*Liquid Vapor phase change

*Direct Liquid cooling*Indirect Liquid cooling

*Impinging jets

*Droplets*Sprays

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Liquid Vapor phase change 

It is also known as TWO PHASE HEAT TRANSFER:

In this a fluid is used as a media to transfer the heat from

source to surrounding, the fluid at liquid state absorbs heat from the hot

source and turns vapor. The vapor gives of the absorbed heat to

surrounding and regains liquid state. The fluid is transported through

closed tube hence it is also called as heat pipe. 

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Mark Aaron Chan, Christopher R. Yap, Kim Choon Ng in 2009

tested a CPU with phase change system and reported that

after modeling, design, and testing of a high flux and yetcompact two-phase CPU cooler, with excellent attributes of

low thermal resistance that are derived from the intrinsic

design features of phase change phenomena and minimal

vapor pressure drop of the device. For the same footprint of a

conventional cooler, the prototype rejects more than twice the

capacity of CPUs of today. The unique design minimizes its

overall size and yet provides adequate area for forced

convection cooling. Testing was conducted over an assorted

heat loads and air flow rates flowing through the fins,

achieving a best performance of 0.206 K/W of device thermal

resistance at a rating of 203 W under an air flow rate of0.98 m3/min.

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Direct Liquid cooling

• In this method of cooling liquid is circulated continuously through the

sources of heat generation using small size pumps.

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Cristina H. Amon, Jayathi Murthy, S. C. Yao, Sreekant Narumanchi, Chi-

Fu Wu, Cheng-Chieh Hsieh in 2001 sudied the effects of direct liquid

cooling for electronics applications and developed the technique fordroplet impingement for integrated cooling of electronics (EDIFICE). The

EDIFICE project seeks to develop an integrated droplet impingement

cooling device for removing chip heat fluxes in the range 70 –100 W/cm2,

employing latent heat of vaporization of dielectric fluids (50 –100 μm

droplets) to achieve these high heat removal rates. Micro-manufacturing

and micro electro-mechanical systems (MEMS) will be discussed as

enabling technologies for innovative cooling schemes recently proposed.

 A novel feature to enable adaptive on-demand cooling is MEMS sensing

(on-chip temperature, remote IR temperature and ultrasonic dielectric

film thickness) and MEMS actuation. EDIFICE will be integrated within

the electronics package and fabricated using advanced micro-manufacturing technology (e.g., deep reactive ion etching (DRIE) and

complementary metal-oxide-semiconductor (CMOS) CMU-MEMS).

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Indirect Liquid cooling

• In this method of electronics cooling the cooling is achieved by convection

heat transfer principles where the liquid is not in contact with the heat

source directly.

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• Yam Lai, Nicolás Cordero, Frank Barthel, Frank Tebbe,Jörg Kuhn, Robert Apfelbeck, Dagmar Würtenbergein 2009 performed experiments with Led’s and with

liquid cooling the thermal design from device toboard to system level has been carried out in thisresearch. Air cooling and passive liquid coolingmethods were investigated and excluded asunsuitable, and therefore an active liquid coolingsolution was selected. Several configurations of theactive liquid cooling system were studied and

optimization work was carried out to find anoptimum thermal performance.

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Impinging jets

• In this method of electronics cooling a jet of air or liquid is directly blown

on to the heated surface in normal orientation

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• Jemmy S. Bintoro, Aliakbar Akbarzadeh, and Masataka Mochizuki in 2005 carriedout experiments with single jet and heat exchangers and reported that thesystem has the cooling capacity of 200 W over a single chip with a hydraulicdiameter of 12 mm. The equivalent heat flux is 177 W/cm2. The cooling systemmaintains the chip’s surface temperature below 95 °C maximum when theambient temperature is 30 °C. De-ionized water is the working fluid of thesystem. For the impinging jet, two different nozzles are designed and tested. Thehydraulic diameters (d N) are 0.5 mm and 0.8 mm. The corresponding volumeflow rates are 280 mL/min and 348 mL/min. Mini channels heat exchanger has 6(six) copper tubes with the inner diameter of 1.27 mm and the total length ofabout 1 m. The cooling system has a mini diaphragm pump and a DC electric fanwith the maximum power consumptions of 8.4 W and 0.96 W respectively. The

coefficient of performance of the system is 21.4• A.M. Kiper in 1984 used water sprays for VLSI circuit cooling new method of

cooling of planar Very Large Scale Integrated (VLSI) circuits which allows one toobtain chip heat fluxes in excess of 500 W/cm2 with acceptable temperaturerises. It is shown that by scaling impinging fluid jet heat transfer technology tosmall geometrical dimensions, and by using water as the coolant, a high-performance cooling system can be designed. The convective heat transfer

coefficients obtained in this method are significantly greater than that obtainedin the convectional liquid cooling technology used for microelectronic devices,including the immersion cooling.

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Droplets

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In this method of electronics cooling droplets of various sizes andat varying velocities are used to remove heat fluxes from a

electronic system

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• H. Oprins, J. Danneels, B. Van Ham, B. Vandevelde, M.

Baelmans in 2008 studied heat transfer rates for varying

droplet velocities and It is shown that the internal droplet

flow exhibits a parabolic characteristic at one hand and thatthe presence of two convection cells decreases the heat

transfer to the lower part of the droplet, thereby limiting the

overall heat transfer through the droplet. A typical

enhancement of the heat transfer with a factor 2 is achieved

with respect to the minimal value that would be obtained

assuming heat conduction as the only means of heat transfer

in the liquid. Further an analytic lumped model is presented

to estimate the transient average droplet temperature with an

accuracy of 5% compared to the full transient computationalfluid dynamics modeling.

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Sprays

Thermal Management- Electronic Cooling

In this system to remove chip level heat fluxes the liquid or is

sprayed using number of nozzles on the heated surface.

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• B.Q. Li, T. Cader, J. Schwarzkopf, K. Okamoto, B. Ramaprian An experimentaland inverse computational study is presented of spray cooling ofmicroelectronics with an emphasis on the spray angle effects on cooling

performance. A thermal test chip provides the heated target, and is cooledby a single pressure swirl atomizer. Thermal readings were taken at thespray angles of 0 –60°, at a fixed distance of 1.4 cm from the heated diesurface. An inverse heat transfer computational algorithm is developed tocalculate the unknown spray cooling heat fluxes using the measuredtemperature data inside the die. The computational scheme is acombination of the finite element method and the truncated single value

decomposition with the discrepancy principle for determining the optimaltruncation threshold value. Good agreement is obtained between theexperimental measurements and calculated results. For this particularsystem, a direct estimate using temperature readings at two adjacentpoints would produce incorrect heat flux results and an inverse algorithm isdeemed essential if an accurate heat flux is to be obtained from the

measurements. It is found that a major cause for the drop-off is thereduction in spray volumetric flux delivered to the die at the greater sprayangles.

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Research Status

Thermal Management- Electronic Cooling

*Liquid Vapor phase change- 5853

*Direct Liquid cooling- 7117*Indirect Liquid cooling-1737

*Impinging jets-549

*Droplets-2005*Sprays-1854

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0

1000

2000

3000

4000

5000

6000

7000

8000

   L   i  q   u   i  d   v  a

  p  o  r   p   h  a

  s  e   c   h  a

  n  g   e

   D   i  r  e

  c   t    L   i  q 

  u   i  d   c  o  o   l   i  n

  g 

   I  n  d   i  r  e

  c   t    L   i

  q   u   i  d

   c  o  o   l   i  n  g 

 

   I  m  p   i  n  g    i  n

  g     j   e   t

  s

   D  r  o  p   l  e   t

  s

  S  p  r  a  y  s

Series1

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CONCLUSION

• Number of solutions have been used till date for electronicscooling problem, as the working demands are higher andheat flux being induced is increasing with time still asatisfactory solution can be put into action

• For electronics cooling with jet impingement experiments

can be performed by varying the nozzle shapes and to breaklaminar boundary layer various flow patterns can be used toenhance the heat transfer rates.

• Some fin geometries are in practice till date a compromisebetween cost and efficiency can be attained by varying the

arrangements and fin geometries.

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• for spray cooling the pressurized air and liquid mixture ca beused as mist to spray and combinations of air and liquid canbe studied at various flow rates to determine the best suitedflow-mixture combination.

• parabolic droplets of various cooling fluids can be studied forthis to remove the heat generated

• From the graph it is also clear that a lot of scope is there for

work in jet impingement cooling area.• Cross cutting of flat fins into multiple sections is also suggested

to improve heat transfer coefficient.

• Augmentation of the fins can also improve the performance.

• Jet impingement cooling using high speed blow directedtowards the base of the fin arrangement is effective.

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References1. Michroelectromechanical system – based evaporative thermal management of high heat flux electronics,

Journal of heat and mass transfer, Volume 127,January 2005, Pages 66-75, Cristina H. Amon, S.C. Yao, C. F.Wu,C.C. Hseih.

2. Modeling and testing of an advanced compact two-phase cooler for electronics cooling International Journal of Heat and Mass Transfer , Volume 52, Issues 15-16, July 2009, Pages 3456-3463,Mark Aaron Chan, Christopher R. Yap, Kim Choon Ng

3. The experimental investigation on thermal performance of a flat two-phase thermosyphon International Journal of Thermal Sciences, Volume 47, Issue 9, September 2008, Pages 1195-1203,MingZhang, Zhongliang Liu, Guoyuan Ma

4. MEMS-enabled thermal management of high-heat-flux devices EDIFICE: embedded droplet impingementfor integrated cooling of electronics Experimental Thermal and Fluid Science, Volume 25, Issue 5, November 2001, Pages 231-242,Cristina H.

Amon, Jayathi Murthy, S. C. Yao, Sreekant Narumanchi, Chi-Fu Wu, Cheng-Chieh Hsieh5. An absorption based miniature heat pump system for electronics cooling 

International Journal of Refrigeration, Volume 31, Issue 1, January 2008, Pages 23-33 Yoon Jo Kim, Yogendra K. Joshi, Andrei G. Fedorov

6. Development of a chip-integrated micro cooling device Microelectronics Journal , Volume 34, Issue 11, November 2003, Pages 1067-1074 J. Darabi, K. Ekula

7. Modeling and testing of an advanced compact two-phase cooler for electronics cooling International Journal of Heat and Mass Transfer , Volume 52, Issues 15-16, July 2009, Pages 3456-3463 Mark Aaron Chan, Christopher R. Yap, Kim Choon Ng

8. Liquid cooling of bright LEDs for automotive applications  Applied Thermal Engineering, Volume 29, Issues 5-6, April 2009, Pages 1239-1244 Yan Lai, Nicolás Cordero, Frank Barthel, Frank Tebbe, Jörg Kuhn, Robert Apfelbeck, Dagmar Würtenberger

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9. Micro cooling systems for high density packaging Revue Générale de Thermique, Volume 37, Issue 9, October 1998, Pages 781-787  Bernd Gromoll

10. A closed-loop electronics cooling by implementing single phase impinging jet and minichannels heat exchanger  Applied Thermal Engineering, Volume 25, Issues 17-18, December 2005, Pages 2740-2753,Jemmy S. Bintoro, Aliakbar Akbarzadeh, Masataka Mochizuki

11. Impinging water jet cooling of VLSI circuits International Communications in Heat and Mass Transfer , Volume 11, Issue 6, November-December 1984, Pages 517-526 A.M. Kiper

12. Convection heat transfer in electrostatic actuated liquid droplets for electronics cooling Microelectronics Journal , Volume 39, Issue 7 , July 2008, Pages 966-974 H. Oprins, J. Danneels, B. Van Ham, B. Vandevelde, M. Baelmans

13. Spray angle effect during spray cooling of microelectronics: Experimental measurements andcomparison with inverse calculations 

 Applied Thermal Engineering, Volume 26, Issue 16, November 2006, Pages 1788-1795 B.Q. Li, T. Cader, J. Schwarzkopf, K. Okamoto, B. Ramaprian

14. Intermittent spray cooling: A new technology for controlling surface temperature International Journal of Heat and Fluid Flow , Volume 30, Issue 1, February 2009, Pages 117-130,Miguel R.O. Panão, António L.N. Moreira

15. WWW.sciencedirect.com