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December 31, 2003. Study on Effective Thermal Conduction of the Nanoparticle Suspension. Calvin Hong Li Department of Mechanical, Aerospace & Nuclear Engineering Rensselaer Polytechnic Institute Troy, NY 12180. Presentation Outline. Introduction Background Effective Thermal Conduction - PowerPoint PPT Presentation
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Study on Effective Thermal Study on Effective Thermal Conduction of the Conduction of the
Nanoparticle SuspensionNanoparticle SuspensionCalvin Hong LiCalvin Hong Li
Department of Mechanical, Aerospace & Department of Mechanical, Aerospace & Nuclear Engineering Nuclear Engineering
Rensselaer Polytechnic InstituteRensselaer Polytechnic InstituteTroy, NY 12180 Troy, NY 12180
December 31, 2003
Presentation OutlinePresentation Outline
IntroductionIntroductionBackgroundBackgroundEffective Thermal Effective Thermal ConductionConductionAdsorption LayerAdsorption LayerBrownian MotionBrownian MotionConclusionsConclusions
BackgroundBackground
Nano tech is a very promising field and the Nano tech is a very promising field and the current focus of the world.current focus of the world.
Nanoparticle suspension is a kind of new heat Nanoparticle suspension is a kind of new heat transfer material which has very novel thermal transfer material which has very novel thermal properties. The study on it has covered chemical properties. The study on it has covered chemical physics, interfacial phenomena, heat and mass physics, interfacial phenomena, heat and mass transfer and some even grand fundamental transfer and some even grand fundamental fields. This new material will accompany the fields. This new material will accompany the advancing of future engineering and science advancing of future engineering and science development. development.
Research on Effective Thermal Research on Effective Thermal ConductivityConductivity
Theoretic StudyTheoretic Study Hamilton and CrossHamilton and Cross (( 19621962 ))
Maxwell (1881)Maxwell (1881)
Experimental StudyExperimental Study Transient Wire Method Transient Wire Method (Nagasaka & Nagashima) (Nagasaka & Nagashima) Thermal Probe MethodThermal Probe Method Other methodsOther methods
pffppffpfe kkknkkknknkkk 1/11/
12
131
f
e
k
k
12
131
f
e
k
k1s
fk
k
Working TheoryWorking Theory
Thermal Probe MethodThermal Probe MethodTransient Wire MethodTransient Wire Method
Calculating the effective thermal Calculating the effective thermal conductivity by measuring the change of conductivity by measuring the change of voltage of the probe and wirevoltage of the probe and wire
2730 *10851.5(*1094851.3 ttRR )--
5772.0
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00 r
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Experimental SetupExperimental Setup
Current StudyCurrent Study
Preparation of Nanoparticle Suspension Preparation of Nanoparticle Suspension
Study of Effective Thermal Conductivity Study of Effective Thermal Conductivity
Study on Other thermal Properties and Study on Other thermal Properties and Applications Applications
ObjectiveObjective
Measure the effective thermal conductivityMeasure the effective thermal conductivity
Reveal the interaction between particle and fluid
Study the effect of Brownian motion on effective thermal conductivity
Preparation of Nanoparticle Preparation of Nanoparticle SuspensionSuspension
MethodsMethods :: One-step MethodOne-step Method
Two-step MethodTwo-step Method
StabilityStability :(:( 11 )) PH ValuePH Value ;; (( 22 )) Chemical MethodChemical Method ;; (( 33 )) Physical MethodPhysical Method 。 。
Material: SiO2 nanoparticle, Mean diameter Material: SiO2 nanoparticle, Mean diameter 25nm 25nm ,, PurityPurity (( >99.9%>99.9% ),), non non crystal.crystal.
Pure water and ethanolPure water and ethanol
Preparation of the suspension: dispersed Preparation of the suspension: dispersed with microwave.with microwave.
Setups Error EvaluationSetups Error Evaluation
纯水测量值
0. 45596
0. 45598
0. 456
0. 45602
0. 45604
0
1.1
2.21
3.83
4.94
6.05
7.67
8.78
10.4
11.5
12.6
14.3
15.4 17
s时间
v电
压
Thermal Probe Transient wire
Experimental ResultsExperimental Results Thermal Probe MethodThermal Probe MethodThe higher of the suspension’s temperature, the higher the The higher of the suspension’s temperature, the higher the
effective thermal conductivityeffective thermal conductivityThe higher the ratio of nanoparticle in the suspension, the The higher the ratio of nanoparticle in the suspension, the
higher the effective thermal conductivity higher the effective thermal conductivity
Si O2 nanopart i cl e suspensi on
0. 599
0. 649
0. 699
0. 749
0. 799
0 20 40 60
temperature C
Effec
tive
the
rmal
cond
ucti
vity
w/(m
*K)
理论纯水
测量用水
质量浓度0. 1 %为
质量浓度0. 5 %为
Experimental ResultsExperimental ResultsTransient Wire MethodTransient Wire MethodWt ratio of 0.1%Wt ratio of 0.1% ,, effective thermal conductivity is 9.452% effective thermal conductivity is 9.452%
higher than pure waterhigher than pure water ;;Wt ratio of 0.2%Wt ratio of 0.2% , , effective thermal conductivity is 10.6% effective thermal conductivity is 10.6%
higherhigher ;;Wt ratio of 0.5%Wt ratio of 0.5% ,, 17.4% higher17.4% higher 。 。
Si O2 nanoparti cl e suspensi on
62
64
66
68
70
72
0. 1 0. 2 0. 5
wt rati o %
effec
tive
the
rmal
cond
ucti
vity
*10
0w/
(m*K
)
Results AnalysisResults Analysis With the high surface/volume ratio of With the high surface/volume ratio of
nanoparticles, basefluid is adsorbed on the nanoparticles, basefluid is adsorbed on the surface of nanoparticles. This lay of adsorbed surface of nanoparticles. This lay of adsorbed basefluid can help nanoparticles from basefluid can help nanoparticles from agglomerating. Meanwhile, the particles do the agglomerating. Meanwhile, the particles do the Brownian motion in the basefluid, which will help Brownian motion in the basefluid, which will help to form a micro convection around them. the to form a micro convection around them. the adsorption and Brownian motion help the adsorption and Brownian motion help the nanoparticle suspension to have very novel nanoparticle suspension to have very novel effective thermal conduction. effective thermal conduction.
Action between surface atoms and Action between surface atoms and fluid atomsfluid atoms
])2/([ 23
24 OOSi -+
or 2
5.24 OSi
3
24 2/OSi
Agglomeration of NanoparticlesAgglomeration of Nanoparticles
SiO2nanoparticles Hitachi 200CX TEM 1:120,000
Distribution of particles and the Distribution of particles and the agglomerationagglomeration
Four particle agglomerati-on
Two particle agglomerati-on
Single particle
huge agglomerati-on
Multiparticl-e agglomerati-on
Distribution of particles and the Distribution of particles and the agglomerationagglomeration
Agglomerations
The calculation of the thickness of The calculation of the thickness of adsorption layeradsorption layer
321321 GGGGGG
Particle, adsorbed layer and free basefluid
)( Ad : Two dimension surface work
when 0dG , there is 03
Addn ii
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0
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surf
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A 1
1
then
Study on the interaction between Study on the interaction between particles and basefluidparticles and basefluid
There are two ways how the heat is conducted in There are two ways how the heat is conducted in fluid. One is that molecules move in a area which is like fluid. One is that molecules move in a area which is like a cell, the other is that some molecules can get high a cell, the other is that some molecules can get high energy and move out the original cell to other adjacent energy and move out the original cell to other adjacent cells. So it seems that the Brownian motion of cells. So it seems that the Brownian motion of nanoparticles will change this process greatly by nanoparticles will change this process greatly by breaking the cell or helping molecules move to other cell breaking the cell or helping molecules move to other cell with rather low energy. And therefore the suspension with rather low energy. And therefore the suspension shows greater effective thermal conductivityshows greater effective thermal conductivity 。。
Analysis force acted on nanoparticlesAnalysis force acted on nanoparticles
Simulation of the Brownian motion effect of nanoparticles Simulation of the Brownian motion effect of nanoparticles having on basefluidhaving on basefluid
Force AnalysisForce Analysis
(( 11 )) Thermal Swimming ForceThermal Swimming Force : :
(( 22 )) Short range agglomerating forceShort range agglomerating force : :
(( 33 )) Electrostatic ForceElectrostatic Force : :
(( 44 )) Surface tensionSurface tension : :
diameterdiameter WaterWater (( 26 26 centigradecentigrade ))
airair (( 26 26 centigradecentigrade ))
(( umum )) Brownian motionBrownian motion Brownian motionBrownian motion
0.10.1 2.362.36 29.429.4
0.250.25 1.491.49 14.214.2
0.50.5 1.051.05 8.98.9
1.01.0 0.750.75 5.95.9
The displacement of particles with Brownian motion per second ( um )
With heat flux q
and the T gradient ,
Rkn 2/
,
is fluid molecule’s
110-Kn means the movement is in the slipping or temp. jumping area.
The Knudsen number with the particle’s diameter:
mean free moving distance,
CFD SimulationCFD Simulation
Micro convection zone
Particle
Layer of fluid molecules
tkT
x
22
Single particle moving model
Distribution of particles in suspension
The vel oci t y of nano- par t i cl e' s Br owni an mot i on
0
0. 001
0. 002
0. 003
0. 004
0. 005
0. 006
0. 007
0. 008
0. 009
0. 01
5E- 0
7
0.00
0001
0.00
0005
0.00
001
0.00
005
0.00
01
0.00
050.
001
0.00
50.
010.
05 0.1
0.5 1
1.5 2
t i me ( s)
Velo
city
(m/s
)
V
Velocity of Brownian motion
One, two and ten particles One, two and ten particles casescases
Mesh for ten particles caseMesh for single particle case
Temp. field around one particle Pressure field around one particle
Velocity field around one particleMoving situation
Comparing and contrasting of one Comparing and contrasting of one and two particles casesand two particles cases
Temperature field comparing and contrasting horizon plate Temperature field comparing and contrasting
upright plate
Ten particles caseTen particles case
Temperature field Velocity field
ConclusionConclusion Observation on the particles and their Observation on the particles and their
agglomerationagglomeration
Getting the effective thermal conductivity data Getting the effective thermal conductivity data through two kind of methods. through two kind of methods.
Calculating the thickness of adsorbing layer Calculating the thickness of adsorbing layer
Simulating the Brownian motion and its effect.Simulating the Brownian motion and its effect.
Other Study on Nanoparticle Other Study on Nanoparticle SuspensionSuspension
Study on the viscosityStudy on the viscosity
Study on the capillary performance and Study on the capillary performance and
chemical behavior chemical behavior
Study on the application as the refrigerant Study on the application as the refrigerant in MEMSin MEMS
MD SimulationMD Simulation In case that there is not a good way to In case that there is not a good way to
observe the adsorbed layer basefluid observe the adsorbed layer basefluid moleculesmolecules ,, the MD method should be the MD method should be used to study the adsorption process and used to study the adsorption process and its effect on the energy. Through the MD its effect on the energy. Through the MD simulation, hoping to get the information of simulation, hoping to get the information of kinetic energy, potential energy and other kinetic energy, potential energy and other changes in the process. changes in the process.
Effects between fluid moleculesEffects between fluid molecules Since the fluid molecules have polarity, based on the Since the fluid molecules have polarity, based on the
L-J modelL-J model ,, the model for the effect between fluid the model for the effect between fluid
molecules can be Stockmayer potential modelmolecules can be Stockmayer potential model ::
,,
44,,, 213
0
21
612
21 rrrrU
Brownian MotionBrownian Motion
Get experimental data of difference Get experimental data of difference viscosity basefluid, Find out the viscosity basefluid, Find out the relationship between viscosity and relationship between viscosity and effective thermal conductivity. Hence effective thermal conductivity. Hence reveal deeper the contribution of Brownian reveal deeper the contribution of Brownian motion.motion.
Thank you!Thank you!
And Happy NewAnd Happy New Year! Year!