July 19, 2010Thesis Defense, USC Experimental Investigation of the Effect of Copper Nanowires on...

July 19, 2010 Thesis Defense, USC

Experimental Investigation of the Effect of Copper Nanowires on Heat Transfer and Pressure Drop

for a Single Phase Microchannel Heat Sink

M.S. Thesis DefenseJuly 19, 2010

M. Yakut Ali, M.S. Candidate Dr. Jamil A. Khan, Advisor

Outline of the presentation

Introduction Overview of Heat Sinks for Electronics Cooling Motivation / Problem Statement

Experimental facilities/ Setup Synthesis of Cu Nanowires on Cu Heat Sink Characterization of Cu Nanowires using SEM Flow Loop and Test Section Design & Fabrication Data acquisition and Post Processing

Results and Discussions

Summary and Future Works


Image Source : http://en.wikipedia.org/wiki/Heat_sink

Overview of Heat sinks for Electronics Cooling

A heat sink is a term for a component that efficiently transfers heat generated within a solid material to a fluid medium, such as air or a liquid.

For high power electronics cooling, many alternative cooling schemes have been examined in recent years to meet this demand.

Microprocessor heat sink

Heat sinks for Electronics Cooling

Motherboard Heat sink

Liquid Cooled Microchannel Heat Sink is on The Rise

http://en.wikipedia.org/wiki/Heat_sink

Microchannel Heat Sink

Tuckerman and Pease 1981

removal of large amount of heat from a small area

Dense package

Small foot-print cooling scheme

Larger surface area per unit volume

Dimensions from 10 to 1000 µm

Channels may be rectangular, circular or trapezoidal

Single-phase/two-phaseDixit et al. 2007

Microchannel Heat Sink

Thesis Defense, USCJuly 19, 2010

Enhancing Microchannel Heat Transfer is the Focus!

Ref. : Moore GE 1965 Electronics 38 : 114–117 and Intel Websitehttp://en.wikipedia.org/wiki/Moore's_law

Moore’s Law

Motivation

Motivation

# of Transistors in a given area doubles every 2 years due to reduction of transistor size

http://en.wikipedia.org/wiki/Moore's_law

Advancement in Nanotechnology

Motivation

Li C. et al. 2008, Small

Chen R. et al. 2009, Nano Letters Diatz et al. 2006


Mudawar et al. 2009, IJHMT

Launay et al. 2006, Microelectronics Journal

Proposed Investigation

Proposed Investigation

Thesis Defense, USCJuly 19, 2010

Cu nanowiresHeat Flux from Bottom Heat Flux from Bottom

Inlet

Outlet

Typical Microchannel Heat Sink

Nanowires Coated Microchannel Heat Sink

Synthesis of Cu nanowires on Cu heat sink Characterization of CuNWs Design and Fabrication of Experimental Thermal and Flow loop Design Experimental metrics Assessment and Comparison of the thermal performance and pressure drop results Investigation of surface Morphology before and after the heat transfer experiments

Approach:

Cu Nanowires Growth on Cu Heat Sink

Synthesis and Characterization of Nanowires on Heat Sink

Synthesis : Electrochemical technique

Tao Gao et al. 2002

Copper Heat Sink

Cu Heat Sink

PAA Template

PAA Template on Cu Substrate

Electrochemical Deposition

Washing away PAA template


Growth Conditions

Voltage -0.3 V

Time 3600 s

Electrolyte CuSO4 .5H2 O+ H2SO4


Experimental Facilities

Flow loop


Top plate/ cover plate

Base plate

Cu foil

Intermediate plate

Rubber Cushion

Cu foil

Cu heat sink

Pre-moistened filter paper

PAA template

Exploded View of the Reactor Components



Digital Photographs of Reactor components


Assembled Reactor

Electrochemical Work Station

Characterization of Cu Nanowires

Characterization : SEM


Bare Cu Heat Sink

Cu Nanowires on Heat Sink

Experimental Facilities for Convective Heat Transfer Experiments

Flow Loop


Test Section

Data AcquisitionLiquid Reservoir Gear Pump

Degasifier and Filter

Control Valve

Liquid ReservoirComputer

Schematic diagram of the flow loop



Digital Photographs




Cover plate

Housing

Coolant in

Coolant out

Pressure ports

Cartridge Heater

Insulation Block

Insulation Block

Base plate / Support plate

Inlet plenum

Copper Heat Sink

Test Section

Thermocouples Location

Exploded view of Test Section Components

Experimental Facilities for Convective Heat Transfer Experiment


Insulation Block

Support Plate

Cover Plate

Outlet port

Housing

O-Ring Seal

Cartridge HeaterBolts

Inlet port

Insulation Block

Assembly of the test section

Digital Photographs of Test Section Components

Summary


Experimental Procedure, Postprocessing and Uncertainty Analysis

Postprocessing


Sensible Heat Gain by Coolant

Power Input to Cartridge Heater

Average Heat Transfer Coefficient

Log Mean Temperature Difference

Nomenclature: ρ = Density of water at Tm

Cp = Specific Heat of Water at Tm

V = VoltageI = CurrentAht =Heat Transfer AreaTi = Inlet TemperatureTo = Outlet Temperature Ts = Surface TemperatureTm = Mean TemperatureTs,j =Heat Sink Surface Temperature Tc,j=Thermocouple readingkCu = Thermal Conductivity of Copper s = Distance from thermocouple location to top surface q’’ = Heat flux

Heat Sink Surface Temperature


Postprocessing Average Nusselt Number

Hydraulic Diameter

Friction Factor

Nomenclature:

Nu= Nusselt Numberh = Average convective heat transfer coefficientDh = Hydraulic diameterkf = Thermal conductivity of the fluid at Tm Ac = Channel cross sectional areaPw = Wetted Perimeter µ = Viscosity of water at Ti

Q = Flow RateTm = Mean TemperatureL = Length of test sectionPr = Prandtl number∆p = Pressure drop

Dimensionless Hydrodynamic Axial Distance

Reynolds Number

Dimensionless Thermal Axial Distance


Uncertainty Analysis


Parameter Uncertainty

Dh 3%

Re 5%

q 6%

P 1%

∆TLMTD 9%

h 11%

Nu 12%

x+ 5%

x* 5%

Kline and McClintock :

Measured Parameter

Uncertainty

Pressure 0.25%

Temperature ±0.3 C ̊�

Voltage ±0.01V

Current 0.4%

Flow Rate 0.02%

Measurement Uncertainty Propagated Uncertainty


Test Procedure


Test

#

Reynolds

Number

(Re)

Width, w

(mm)

Height,

b (µm)

Length,

L (mm)

Hydraulic

Diameter

Dh ( µm)

Aspect ratio,

α = w/b

(Dimensionless)

1 106 5 360 26 672 13.89

2 208 5 360 26 672 13.89

3 316 5 360 26 672 13.89

4 428 5 360 26 672 13.89

5 529 5 360 26 672 13.89

6 636 5 360 26 672 13.89

Results

Results : Surface Wettability Characteristics


58.070.5 E

Bare Cu Heat Sink CuNWS Coated Heat Sink

Improvement in Surface Wettability!

Results

Results : Bare Microchannel Heat Sink


100 200 300 400 500 600 700 8000

1

2

3

4

5

6

7

Experimental results Hausen [39] Qu [40] Harms [41]

Re

Nu

Heat Transfer Results

Re 106 208 316 428 529 636

x+ 0.363 0.186 0.123 0.09 0.073 0.060

x* 0.067 0.032 0.021 0.015 0.012 0.010

Results




0 100 200 300 400 500 600 7000

1000

2000

3000

4000

5000

6000

7000

Heat transfer coefficient

Re

h (

W/m

2k)

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080

1000

2000

3000

4000

5000

6000

7000

Heat transfer coefficient

x*

h (

W/m

2k)

Results




0 1 2 3 4 5 6 730

35

40

45

50

55

60

Re=106Re=208Re=316Re=428Re=529Re=636

Thermocouple number along heat sink

Hea

t S

ink

Tem

per

atu

re

(EC)

Results



Pressure Drop Results

0 100 200 300 400 500 600 7000

500

1000

1500

2000

2500

Pressure Drop

Re

Pre

ssu

re d

rop

(P

a)

0 100 200 300 400 500 600 70050

60

70

80

90

100

Calculated from experimentsMorini [43]Shah and London [44]

Re

fRe

Results


Results : Comparison between Bare and CuNWs Coated Microchannel Heat Sink


0 100 200 300 400 500 600 7000

1

2

3

4

5

6

7

8

Bare Microchannel

CuNWs coated heat sink

Re

Nu

Results




0 100 200 300 400 500 600 7000

1000

2000

3000

4000

5000

6000

7000

Bare Microchannel Heat sinkCuNWs coated heat Sink

Re

h

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080

1000

2000

3000

4000

5000

6000

7000

Bare Microchannel heat sinkCuNWs coated heat sink

x*

h

Results




0 1 2 3 4 5 6 750

51

52

53

54

55

56

57

58

59

60

Re=106

Bare microchannel heat sink

CuNWs coated heat sink

Thermocouple number along heat sink

Tem

per

atu

re (

EC)

Results



Pressure Drop Results

0 100 200 300 400 500 600 7000

500

1000

1500

2000

2500

3000

Bare MicrochannelCuNWs coated microchannel

Re

Pre

ssu

re d

rop

(P

a)

Results

Results : Assessment of Surface Morphology SEM Images After Heat Transfer Experiments

Summary and Future Works

Summary Cu Nanowires have been successfully grown on heat sink Experimental flow loop and test section has been designed and fabricated Heat transfer and pressure drop characteristics have been measured Enhancement in single phase microchannel heat transfer has been

demonstrated

Future Works

Experimental investigation of effect of CuNWs on two phase heat sink Fabrication of CuNWs on lower aspect ratio microchannels


PublicationsJournal Publications

Ali, M. Y.; Yang, F.; Fang, R.; Li, C.; Khan, J. “Investigation on the Effect of Cu Nanowires on Heat transfer and Pressure drop Characteristics of Single Phase Microchannel Heat Sink” , To be Submitted

Conference Proceedings

Ali, M. Y.; Yang, F.; Fang, R.; Li, C.; Khan, J. “Effect of 1D Cu Nanostructures on Single Phase Convective Heat transfer of Rectangular Microchannel” ASME/JSME 8th Thermal Engineering Conference, Mar 13-17, 2011, Honululu, Hawaii, USA (Abstract has been accepted).


Acknowledgement

Acknowledgement

Special thanks to Dr. Guiren Wang and Dr. Chen Li, Mechanical Engineering, USC and Dr. Qian Wang, Department of Chemistry & Biochemistry, USC.

Thanks to research group members, speciallyFanghao YangRuixian Fang

Thanks goes to ONR for financial support under ESRDC Consortium.

Acknowledge the facilities of EM Centre, USC.


Conclusion

Thanks!

?


July 19, 2010Thesis Defense, USC Experimental Investigation of the Effect of Copper Nanowires on...

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