enhanced two-phase cooling

Enhanced Two-Phase Cooling

Darin Sharar: GTS / Army Research Laboratory*, University of Maryland+

Contributors: Brian Morgan*, Nicholas Jankowski*, and Avram Bar-Cohen+

Sensors & Electron Devices Directorate

U.S. Army Research Laboratory

2800 Powder Mill Rd.

Adelphi, MD 20783

[email protected]

[email protected]

Presented March 14, 2012

Outline

Two-phase offset fin minichannel cold plate

•Introduction

•Modeling

•Design and fabrication

•Performance

Two-phase surface enhancements

•Introduction

•Passive techniques

•Nucleate boiling enhancement

•Convective vaporization enhancement

1

Introduction & Motivation

Vehicle / Mission

Payloads

Distributed Power Conversion

Electronics

• AC/AC converters

• DC/DC converters

• Output switches

• Power inverters

Transition to more-electric vehicle platforms

– Replacing mechanical systems with electronic

equivalents

– Aligned efforts have lead to increased power

density electronics

Army-specific vehicle cooling goals

– Bypass coolant from 80-100 ºC engine loop

– Reduce filtering requirement

IGBT switching module

2

[1] D.J. Sharar, N.R. Jankowski, B. Morgan, 2011, “Two-phase minichannel cold plate

for Army vehicle power electronics,” ASME InterPACK2011-52079, pp. 133-142.

Single- & Two-Phase Predictive

Modeling

Dh ~ 2.1 mm

Offset fin minichannel cold plate

[2] F. Incropera, D. Dewitt, T. Bergman, A. Lavine, “Fundamentals of Heat and Mass Transfer; Sixth Edition”,

John Wiley & Sons, Inc., 2007, pp.486-559.

[3] J.C. Chen, “Correlation for Boiling Heat Transfer to Saturated Fluids in Convective Flow”, Industrial and

Engineering Chemistry – Process Design and Development”, Vol. 5 No. 3, 1966, pp. 322-329.

Two-phase can dissipate an order of

magnitude more heat for a fixed flowrate

1-20 times increase in heat transfer

coefficient

– Single-phase developing flow [2]

– Two-phase flow boiling [3]

1.5 to 6.5 times thermal resistance

improvement

000,8420186,4single mmTCmq p

000,130,1000,257,25.0lgtwo mmxhmq

0

0.2

0.4

0.6

0

10000

20000

30000

40000

50000

60000

0 1.5 3 4.5 6 7.5

Tw

o-p

hase Q

uality

(x)

Heat

Tra

nsfe

r C

oeff

icie

nt

(W/m

²K)

Position (cm)

2.17 cm³/s single-phase

2.17 cm³/s two-phase

quality (x)

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0 10 20 30 40

Are

a-S

pecif

ic T

herm

al

Resis

tan

ce (

cm

²K/W

)

Flowrate (cm³/s)

Single-phase correlation

Chen correlation

0

10

20

30

40

50

0 10 20 30 40

Dis

sip

ate

d H

eat

(kW

)

Flowrate (cm³/s)

Latent Heat (x=0.5) Sensible Heat (75C delta) Sensible Heat (20C delta)

3

Offset Fin Minichannel Cold Plate

Design & Fabrication

Cold plate design

– External footprint of 6.8 x 2.7 x 0.9 cm

– Offset-fin minichannel cold plate • Brazed copper

• 15 rows of offset fins

• One hundred fifty 0.85 x 0.6 x 0.05 cm

copper fins

• Inlet and outlet plenums

– Originally designed for single-phase

Cold plate fabrication

– Electroless Nickel Immersion Gold

(ENIG) plating process

– Twelve 50 Ω 0.86 cm² American

Technical Ceramic (ATC) chip resistors • 80/20 AuSn solder

– Solder-attached wire leads

– Swagelok tube fittings

– Boron Nitride for uniform emissivity [4]

[4] T.E. Salem, D. Ibitayo, B.R. Geil, “Calibration of an Infrared Camera for Thermal Characterization of High

Voltage Power Electronic Components”, Proc. IEEE Instrumentation and Measurement Tech. Conf., Ottawa,

Ontario, Canada, 2005, pp. 651-654.

Offset fins

Inlet/outlet plenums

ENIG plating Chip resistors

80/20 AuSn solder

4

Experimental Setup and Testing

Procedure

Performance criteria

– Input and output power

– Pressure drop vs flowrate

– Thermal resistivity vs flowrate

– Heat dissipated vs pumping power

– Chip temperature vs downstream position

Test parameters

– 25ºC and 80ºC single-phase water

– 99ºC saturated (two-phase) water

– >1 kW input power

– Flowrates 0-40 cm³/s

– Pressure drop < 35 kPa

Heat pump

Pressure

transducers

Rotameters

Condenser

Inline

heater

Power

supply

Thermal

camera

T1

T2 T3

T4

Experimental setup Test procedure

Test Tfluid in Tchip max ∆Tchip

1phase 80 ºC 100 ºC 20 ºC

2phase 100 ºC 135 ºC 35 ºC

0

20

40

60

80

100

120

140

0 50 100 150 200 250

Ch

ip T

emp

erat

ure

(°C

)

Time (s)

Single-phase 25C Single-phase 80C Two-phase

5

Area-Specific Thermal Resistance

Thermal resistance model

Agreement between experimental

and predicted results

– Single-phase -30% • Deviation due to spreading,

turbulence, and mixing

– Two-phase ±20% • Offset fins altered flow regime and/or

affected the wall thin liquid film

• Within ±25% typical for Chen [5]

chippfinspredictedchip

ACmAhkA

LR

2

11"

Conduction

Convection

[5] A. Bar-Cohen, E. Rahim, “Modeling and Prediction of Two-Phase Microgap Channel Heat Transfer

Characteristics”, Heat Transfer Engineering, Vol. 30 No. 8, 2009, pp. 601-625.

Experimental calculation

Two-phase outperforms single-phase

– 1.2 times improvement @ 40 cm³/s

– 4.8 times improvement @ 0.31 cm³/s

chip

chipchip

P

ATR

"

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0 10 20 30 40 50

Are

a-S

pe

cif

ic T

he

rma

l R

es

ista

nc

e

(cm

²K/W

)

Flowrate (cm³/s)

25C

80C

99C two-phase

Single-phase correlation

Chen correlation

0.34 cm²K/W

0.29 cm²K/W

1.5 cm²K/W

0.31 cm²K/W

6

Chip-to-Chip Temperature Variation

Physical causes for diverging

performance

– Single-phase developing flow [2]

– Downstream sensible heating

– Boiling occurs at nearly isothermal

conditions

x=0-0.068 m x*=.613 m

[2] F. Incropera, D. Dewitt, T. Bergman, A. Lavine, “Fundamentals of Heat and Mass Transfer; Sixth Edition”,

John Wiley & Sons, Inc., 2007, pp.486-559.

-9

-6

-3

0

3

6

9

∆T

fro

m A

ve

rag

e

(ºC

)

Chip Location

25C

80C

99C

64W @ 0.4cm³/s

∆T = 15.4 ºC

∆T = 1.50 ºC

x=0.075

Varying levels of temperature non-

uniformity in all tests

– Minimal improvement at high

flowrates

– Order of magnitude improvement

at 64W and 0.40 cm³/s

T

x(m)

7

Pumping Power Comparison

V pPpump

Two-phase can dissipate more heat

with lower pumping power

– 3 to 5.3 times improvement @ 170

µW pumping power

– 1.3 to 2.2 times improvement @ 270

mW pumping power

Two-phase can dissipate the same

heat with reduced pumping power

– 3 to 4 order of magnitude

improvement @ 16 W/ºC dissipated

heat

Two-phase provides better

temperature uniformity*

– 5.3 times improvement @ 260W

dissipated heat

0

100

200

300

400

500

600

700

0.0001 0.001 0.01 0.1 1 H

ea

t D

iss

ipa

ted

(W

)

Pumping Power (W)

99C

80C

Two-phase

(Device limited)

Single-phase

(Fluid limited)

2.2x

5.3x

*

8

Outline


•Introduction

•Modeling

•Design and fabrication

•Performance


•Introduction

•Passive techniques

•Nucleate boiling enhancement

•Convective vaporization enhancement

9

Surface Enhancement Introduction

[6] L. Cheng, G. Ribatski, and J.R. Thome, 2008, “Two-Phase Flow Pattern Maps:

Fundamentals and Applications,” ASME Applied Mechanics Reviews 61.

hAdTQ

cvnbtp hhh

Distance along channel

He

at T

ran

sfe

r C

oe

ffic

ien

t

Nucleate Boiling

Dominated

Annular Film Flow

Evaporation Dominated

Partial Dryout

10

Nucleate Boiling – Mechanisms

[2] Incropera, F.; Dewitt, D.; Bergman, T.; Lavine, A. Fundamentals of Heat and Mass

Transfer: Sixth Edition; John Wiley and Sons, Inc.: Hoboken, NJ, 2007.

Natural Convection

Onset of Nucleate Boiling

Nucleate Boiling Columns and Slugs

Transition Film Boiling

Stable Film Boiling

Hysteresis

11

Nucleate Boiling – Mechanisms

[2] Incropera, F.; Dewitt, D.; Bergman, T.; Lavine, A.

Fundamentals of Heat and Mass Transfer: Sixth Edition;

John Wiley and Sons, Inc.: Hoboken, NJ, 2007.

Bubble development, growth, and

departure from a nucleation site

Hysteresis

Effect of populating

heated surface with

nucleation sites

12

Nucleate Boiling Enhancement

– Porous Surfaces

Credit: Gilbert Moreno, NREL (all images)

Smooth

copper heat

spreader

Copper heat

spreader with

microporous

(3M) coating 440x magnification

IGBT heat flux: ~17 W/cm² (28W dissipated)

Rth=0.39 K/W (10.92K rise) Rth=0.1 K/W (2.8K rise)

13

Name

/Vendor

Schematic

High Flux Union

Carbide / UOP

Thermoexcel-E

Hitachi

GEWA-K

Wieland-Werke

GEWA-T

Wieland-Werke

GEWA-TX

Wieland-Werke

GEWA-TXY

Wieland-Werke

Turbo-B

Wolverine Tube

[7] Yilmaz, S., Hwalck, J. J., and Westwater, J. W., 1980, “Pool Boiling Heat Transfer

Performance for Commercial Enhanced Tube Surfaces,” ASME Paper 90-HT-41.

q”

(kW

/m²)

ΔTsat (˚C)

Plain GEWA-T

Thermoexcel-E

High Flux


– Reentrant Cavities

14


– Nanoparticle Fluid Additives

Pure water

2

-5 TiO %10

2

-4 TiO %10

2

-3 TiO %10

2

-2 TiO %10

2

-1 TiO %10

Additional nanoparticle fluid additives:

– Al2O3 [9] S.M. You, J.H. Kim, K.H. Kim, 2003, “Effect of nanoparticles on

critical heat flux of water in pool boiling heat transfer,” Appl. Phys. Lett. 83 pp.

3374–3376.

– SiO2 [10] P. Vassallo, R. Kumar, S. D’Amico, 2004, “Pool boiling heat

transfer experiments in silica-water nano-fluids,” Int. J. Heat Mass Transfer 47,

pp. 407-411.

– Fe [11] M.H. Shi, M.Q. Shuai, Z.Q. Chen, Q. Li, and Y. Xuan, 2007, “Sudy on

Pool Boiling Heat Transfer of Nano-Particle Suspensions on Plate Surface,” J. of

Enhanced Heat Transfer 14, pp. 223-231.

[8] H. Kim, J. Kim, M.H. Kim, 2006, “Effect of nanoparticles on CHF enhancement in pool boiling

of nano-fluids,” Int. J. of Heat and Mass Transfer 49, pp. 5070-5074.

15

Surface Enhancement Introduction

[6] L. Cheng, G. Ribatski, and J.R. Thome, 2008, “Two-Phase Flow Pattern Maps:

Fundamentals and Applications,” ASME Applied Mechanics Reviews 61.

hAdTQ

cvnbtp hhh

Distance along channel

He

at T

ran

sfe

r C

oe

ffic

ien

t

Nucleate Boiling

Dominated

Annular Film Flow

Evaporation Dominated

Partial Dryout

16

Convective Vaporization

Enhancement

[12] L.M. Schlager, M.B. Pate, A.E. Bergles, 1989, “The effect of oil on heat transfer and pressure drop

during evaporation and condensation of refrigerant inside augmented tubes,” Iowa State University

Heat Transfer Laboratory Report HTL-50, Ames, IA.

17

Convective Vaporization –

Inner-Grooved Tubes

[13] C. Dang, N. Haraguchi, and E. Hihara, 2010, “Flow boiling heat transfer of carbon dioxide

inside a small-sized microfin tube,” Int. J. of Refrigeration 33, pp. 655-663.

[14] J.R. Thome, 2004, “Engineering Data Book III: Chapter 11; Boiling heat transfer inside

enhanced tubes,” available at [http://www.wlv.com/products/databook/db3/data/db3ch11.pdf]

Credit: Wieland Copper Products, LLC.

Performance Increase:

– 2 to 8x improvement in heat

transfer coefficient [13,14]

– Reduction of early CHF

– 1 to 1.5x pressure drop increase

Standard Tube

Inner-Grooved Tube

18

Convective Vaporization – Twisted

Tape Insert


– 1.2 to 1.5x improvement in heat



– Easy insertion into existing tubes

– 2x pressure drop increase

[15] M.K. Jensen and H.P. Bensler, 1986, “Saturated forced-convection boiling heat transfer

with twisted-tape inserts,” J. Heat Transfer 108, pp. 93-99.

19



Convective Vaporization–

Corrugated Tubes


– 1.2 to 1.8x improvement in heat



– 2x pressure drop increase

[16] S. Laohalertdecha and S. Wongwises, 2011, “An experimental study into the

evaporation heat transfer and flow characteristics of R-134a refrigerant flow ing

through corrugated tubes,” Int. J. of Refrigeration 34, pp. 280-291.

20



Convective Boiling Enhancement –

Microfin/Microchannel Structures

Micro pin-fin heat sink

[18] S. Krishnamurthy and Y. Peles, 2008, “Flow boiling of water in a circular

staggered micro-pin fin heat sink,” Int. J. of Heat and Mass Transfer 51, pp. 1349-

1364.

Microchannel heat sink

200µm

Typical Macrochannel Flow Regimes

Typical Microchannel Flow Regimes

[17] B. Agostini, J.R. Thome, M. Fabbri, B. Michel, D. Calmi, and U.

Kloter, 2008, “High heat flux flow boiling in silicon multi-microchannels –

Part I: Heat transfer characteristics of refrigerant R236fa,” Int. J. of Heat

and Mass Transfer 51, pp. 5400-5414.

21

Conclusions


• 1 to 5x improvement in thermal resistance

• Better temperature uniformity

• Pumping power reduction


• Nucleate boiling – Increase in nucleation sites

• Order of magnitude increase in heat transfer coefficient

• >2x improvement in CHF

• Reduced / eliminated hysteresis

• Superheat reduction

• Convective vaporization enhancement

• 1.2 to 8x improvement in heat transfer coefficient

• Reduction of early film dryout

• Annular flow dominant in microfabricated structures

22

References

[1] D.J. Sharar, N.R. Jankowski, B. Morgan, 2011, “Two-phase minichannel cold plate for Army vehicle power electronics,” ASME InterPACK2011-52079, pp.

133-142.

[2] F. Incropera, D. Dewitt, T. Bergman, A. Lavine, “Fundamentals of Heat and Mass Transfer; Sixth Edition”, John Wiley & Sons, Inc., 2007, pp.486-559.

[3] J.C. Chen, “Correlation for Boiling Heat Transfer to Saturated Fluids in Convective Flow”, Industrial and Engineering Chemistry – Process Design and

Development”, Vol. 5 No. 3, 1966, pp. 322-329.

[4] T.E. Salem, D. Ibitayo, B.R. Geil, “Calibration of an Infrared Camera for Thermal Characterization of High Voltage Power Electronic Components”, Proc.

IEEE Instrumentation and Measurement Tech. Conf., Ottawa, Ontario, Canada, 2005, pp. 651-654.

[5] A. Bar-Cohen, E. Rahim, “Modeling and Prediction of Two-Phase Microgap Channel Heat Transfer Characteristics”, Heat Transfer Engineering, Vol. 30 No.

8, 2009, pp. 601-625.

[6] L. Cheng, G. Ribatski, and J.R. Thome, 2008, “Two-Phase Flow Pattern Maps: Fundamentals and Applications,” ASME Applied Mechanics Reviews 61.

[7] Yilmaz, S., Hwalck, J. J., and Westwater, J. W., 1980, “Pool Boiling Heat Transfer Performance for Commercial Enhanced Tube Surfaces,” ASME Paper 90-

HT-41.

[8] H. Kim, J. Kim, M.H. Kim, 2006, “Effect of nanoparticles on CHF enhancement in pool boiling of nano-fluids,” Int. J. of Heat and Mass Transfer 49, pp. 5070-

5074.

[9] S.M. You, J.H. Kim, K.H. Kim, 2003, “Effect of nanoparticles on critical heat flux of water in pool boiling heat transfer,” Appl. Phys. Lett. 83 pp. 3374–3376.

[10] P. Vassallo, R. Kumar, S. D’Amico, 2004, “Pool boiling heat transfer experiments in silica-water nano-fluids,” Int. J. Heat Mass Transfer 47, pp. 407-411

[11] M.H. Shi, M.Q. Shuai, Z.Q. Chen, Q. Li, and Y. Xuan, 2007, “Sudy on Pool Boiling Heat Transfer of Nano-Particle Suspensions on Plate Surface,” J. of

Enhanced Heat Transfer 14, pp. 223-231.

[12] L.M. Schlager, M.B. Pate, A.E. Bergles, 1989, “The effect of oil on heat transfer and pressure drop during evaporation and condensation of refrigerant inside

augmented tubes,” Iowa State University Heat Transfer Laboratory Report HTL-50, Ames, IA.

[13] C. Dang, N. Haraguchi, and E. Hihara, 2010, “Flow boiling heat transfer of carbon dioxide inside a small-sized microfin tube,” Int. J. of Refrigeration 33, pp.

655-663.

[14] J.R. Thome, 2004, “Engineering Data Book III: Chapter 11; Boiling heat transfer inside enhanced tubes,” available at

[http://www.wlv.com/products/databook/db3/data/db3ch11.pdf]

[15] M.K. Jensen and H.P. Bensler, 1986, “Saturated forced-convection boiling heat transfer with twisted-tape inserts,” J. Heat Transfer 108, pp. 93-99.

[16] S. Laohalertdecha and S. Wongwises, 2011, “An experimental study into the evaporation heat transfer and flow characteristics of R-134a refrigerant flow ing

through corrugated tubes,” Int. J. of Refrigeration 34, pp. 280-291.

[17] B. Agostini, J.R. Thome, M. Fabbri, B. Michel, D. Calmi, and U. Kloter, 2008, “High heat flux flow boiling in silicon multi-microchannels – Part I: Heat transfer

characteristics of refrigerant R236fa,” Int. J. of Heat and Mass Transfer 51, pp. 5400-5414

[18] S. Krishnamurthy and Y. Peles, 2008, “Flow boiling of water in a circular staggered micro-pin fin heat sink,” Int. J. of Heat and Mass Transfer 51, pp. 1349-

1364.

23

Convective Vaporization

Performance Comparison

Inner-Grooved, 75 fin, 23˚ helix

Inner-Grooved, 60 fin, 27˚ helix

Corrugated

Plain

From: [] P. Thors and J.E. Bogart, 1994, “In-tube evaporation of HCFC-22 with enhanced

tubes,” J. Enhanced Heat Transfer 1, pp. 365-377.

He

at

Tra

ns

fer

Co

eff

icie

nt

(W/m

²K)

Mass Velocity (kg/m²s)

enhanced two-phase cooling

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