日本熱物性学会 研究分科会「マイクロナノスケールの熱物性とシステムデサ゛イン」
日時： ２００８年５月２４日（土）１３：３０～１７：００
場所： キャンパス・イノベーションセンター２階，多目的室４

ナノ流体を用いた熱流動特性
について
鳥居 修一
熊本大学大学院自然科学研究科
産業創造工学専攻 先端機械システム講座
Tel&FAx: 096-342-3756
E-mail: torii@mech.kumamoto-u.ac.jp
http://www.mech.kumamotou.ac.jp/Info/lab/heat/torii/toriiindex.html
http://www.gsst.kumamotou.ac.jp/kenkyu/pdf/sangyo/sentan/torii.pdf

内 容
z 研究の背景z 既存の研究成果の紹介
z 研究の目的z 実験装置z 結果と考察（圧力損失、熱伝導率、熱伝達係数）
z まとめ

研究背景
伝熱性能の向上： 機器の小型化

伝熱性能の向上のための方法：
作動媒体への微粒子の混合

粒径がミリ･マイクロオーダーの粒子：•懸濁液の安定性不足•
流路のつまりや侵食
•
圧力損失

研究背景
ナノ技術の進歩：
ナノオーダーの粒子が安価に製造可能

作動媒体にナノオーダーの粒子を混合した，新しい作動媒体が開発： 「ナノ流体」
ミリ・マイクロ流体と比較•伝熱面積の増加•流路のつまりや侵食がない•安定性の増加

Choi, U. S., 1995
“Enhancing Thermal Conductivityof Fluids with Nanoparticles”,
FED-Vol. 231/MD-Vol. 66, pp. 99105, 1995,
The 1995 ASME International
Mechanical Engineering Congress&Exposition, San Francisco, Nov.
12-17, 1995.

既存の研究成果
zzzzz

Lee and Choi:
Performance of microchannel heat exchangers with water, liquid nitrogen and nanofluids as the working
fluid.
Pak and Cho:
Convective heat transfer in the turbulent flow regime using the mixing fluids of water-Al2O3 and waterTiO2.
Xuan and Roetzel:
Effects of transport properties of the nanofluid.
Xuan and Li :Convective heat transfer of water-Cu nanofluids.
Wen and Ding :Convective heat transfer of nanofluids made of water and g-Al2O3 nanoparticles in the laminar flow
region.
Enhancement of convective heat transfer is attributed to a non-uniform distribution of thermal
conductivity and viscosity field and an attenuation of the thermal boundary layer thickness.

zDing et al. :Heat transfer behavior of aqueous suspensions of multi-walled carbon nanotubes(CNT) in the laminartube flow.
Enhancement of the convective heat transfer is ascribed to particle re-arrangement, shear induced
thermal conduction enhancement, reduction of thermal boundary layer thickness, and the higher aspectratio of CNTs.

Experimental investigation into convective heat transfer of nanofluids at theentrance region under laminar flow conditions
Dongsheng Wen, Yulong Ding
International Journal of Heat and Mass Transfer 47 (2004) 5181–5188

Laminar Flow Region>Shah Equation
Turbulent Flow Region>Dittus–Boelter equation(B-D Equation)
Experimental System

x/D=63x/D=116

Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids)
Yulong Ding *, Hajar Alias, Dongsheng Wen, Richard A. Williams
International Journal of Heat and Mass Transfer 49 (2006) 240–250

TEM image of carbon nanotubes.
Effect of Reynolds number on the convective heattransfer coefficient (a) and heat transfer enhancement (b) for
0.1 wt.% CNT at pH = 6.

Heat transfer and flow behaviour of aqueous suspensions of TiO2
nanoparticles (nanofluids) flowing upward through a vertical pipe
Yurong He a, Yi Jin b, Haisheng Chen c, Yulong Ding a,*, Daqiang Cangb, Huilin Lu d
International Journal of Heat and Mass Transfer 50 (2007) 2272–2281

An SEM micrograph ofthe TiO2 nanoparticles(20nm)

Experimental System

Comparison of the measurements with the empirical
Shah and Gnielinski equations for pure water flows.

Pressure drop as a function of Reynolds
number (95 nm nanoparticles)Assessment of the effectiveness of nanofluids for single-phaseand two-phase heat transfer in micro-channels
Jaeseon Lee, Issam Mudawar
International Journal of Heat and Mass Transfer 50 (2007) 452–463

ナノ粒子の体積分率の増加

x/Dh=13x/Dh=48

Experimental Loop

x/Dh=84

Nanofluid settling over 30-day period.

x/Dh=117

Variation of heat transfer coefficient with Reynolds number for different
heat inputs and different Al2O3 concentrations

Investigation on Convective HeatTransfer and Flow Features of Nanofluids
Yimin Xuan, Qiang Li
ASME Journal of Heat Transfer

Cu particles below 100 nm diameter
Experimental System

The friction factors of nanofluids for the turbulent flow

The Nusselt numbers of nanofluids with the Reynolds
numbers and the predicated values from the Dittus-Boeltercorrelation

Thermal conductivity and particle agglomeration in alumina nanofluids:
Experiment and theory
Elena V. Timofeeva, Alexei N. Gavrilov, James M. McCloskey, and Yuriy V.
Tolmachev*
Department of Chemistry, Kent State University, Kent, Ohio 44242, USA
PHYSICAL REVIEW E 76, 061203 , 2007

X. Q. Wang and A. S. Mujumdar, Int. J. Therm. Sci. 46, 1, 2007..

Water

Ethylene Glycol

Thermal conductivity at 23 °C of suspensions prepared from alumina nanoparticlesEffect of nanofluid on the heat transport capability in an oscillating heat pipe
H. B. Ma,a C. Wilson, B. Borgmeyer, K. Park, and Q. Yu
University of Missouri—Columbia, Columbia, Missouri 65211
S. U. S. Choi
Argonne National Laboratory, Argonne, Illinois 60439
APPLIED PHYSICS LETTERS 88, 143116, 2006

Steve Choi
Energy Systems Division
Argonne National Laboratory
The thermal conductivity enhancement of the nanoparticle-water
increases with both nanoparticle concentration and temperature.

TEM micrograph of 2nm gold nanoparticles.

Thermal conductivity enhancement of 2nm goldnanoparticle in waterChoi. Stephen,“Nanofluid Technology: Current Status and Future Research”
theSecond Korean-American Scientists and Engineers Association
Research Trend Study,Vienna, 1998

Normalized conductivity (keff/kBF)Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITYz

A new model that accounts for theBrownian motion of nanoparticles innanofluids captures the concentrationand temperature-dependentconductivity.

z

In contrast, conventional theories withmotionless nanoparticles fail to predict
this behaviour (horizontal dashed line).

z

The model predicts that water-basednanofluids containing 6-nm Cu
nanoparticles (curve with triangles) aremuch more temperature sensitive thanthose containing 38-nm Al2O3 particles,with an increase in conductivity ofnearly a factor of two at 325 K.

Water+ Cu

1.8(6nm)
1.6
1.4

Water+ Al2O3(38.4nm)

1.2
1.0300305

310315320

325

Temperature (K)Temperature-dependent thermal
conductivities of nanofluids at a fixed
concentration of 1 vol.%, normalized to thethermal conductivity of the base fluid.

Pool boiling characteristics of nano-fluids
Sarit K. Das a, Nandy Putra b, Wilfried Roetzel
International Journal of Heat and Mass Transfer 46 (2003)
851–862

TEM of agglomerated nanoaluminium oxide powder.
Pool boiling characteristic of nano-fluids

研究目的

作動媒体： ナノ流体（ダイヤモンド，Al2O3，CuO）
乱流領域における・ 粘度
・ 圧力損失・ 伝熱性能ナノ粒子(b) Al2O3(a) Diamond(c) CuO

TEM image of nanoparticles
Table Physical property of nanoparticles
Nanoparticle

Particle diameter[nm]

Thermal conductivity[W/mk]

Particle shape

Diamond

2~10

2000

SphereAl2O33336

SphereCuO

4720Polyhedronナノ流体(a) Diamond(b) Al2O3Photographs of nanofluids

体積分率：１％(c) CuO

６０日経過後•Water•Nanodiamonod(10nm)(a) 0.4 % and pH=6.62(b) 1.0 % and pH=6.35

Jaeseon Lee, Issam
MudawarInternational Journal ofHeat and Mass Transfer
50 (2007)
Nanofluid settling over 30-day period.

実験装置

Experimental apparatus

加熱部Electrodes

ｔ = 0.17

D = 3.96

150

T1140

140
140
140140
T2
T3T4T5T6 150
L = 1000
Test section

ステンレス管を使用
熱電対：等間隔に設置
直接通電によって流体を加熱

単位：mm

実験条件
Experimental conditions
Re～ 8000

Power [W]200, 235, 270, ･･･

Heating surface area [m2]1.24×10-2

Cross-sectional area [m2]1.23×10-5

流入温度：20oC
加熱量：流入，流出温度の差が約5oCに設定

ナノ流体の熱伝導率

Hamilton, R.L. and Crosser, O.K.,
Thermal conductivity of heterogenenous
two-component system
I&EC Fundamentals , 1(1962), 182-191.

Hamilton and crosserの式⎡ k s + (n − 1)k f − (n − 1)V (k f − k s ) ⎤k = kf ⎢⎥⎢⎣ k s + ( n − 1) k f + V ( k f − k s ) ⎥⎦Table Thermal conductivity of test materials
Thermal conductivity coefficientk [W/m･K]
Water

0.589

Diamond2000

Al2O336CuO

20理論熱伝導率

Thermal conductivity ratio k / kf

1.15

体積分率5％においてダイヤモンドナノ流体の熱伝導率は約16％増加

1.11.05
Diamond
Al2O3
CuO
10.02
Volume fraction

0.04

Fig. Thermal conductivity of nanofluids

ダイヤモンドナノ流体の熱伝導率が最も優れているBatchelorの式
η= 6.2V 2 + 2.5V + 1
η baseViscosity ratio η / η base

結果と考察 [粘度]Batchelor
Diamond
Al2O3
CuO

1.6

1.20
ウベローデ粘度計

0.02
0.04
Volume fraction

Comparison between experimental and theoreticalvalues of viscosity at 20oC結果と考察 [圧力損失]
計算式•ナノ流体の圧力損失Pressure drop [ kPa ]l v2
Δp = λ ⋅⋅ρgd 2g

20

1 vol.％ Al2O3
1 vol.％ CuO
1 vol.％ DiamondWater
Theoretical value

10•ナノ流体の種類による変化
0.5

1Flow late [L/min]

1.5

Pressure drops of water and nanofluids軸方向の局所熱伝達係数
1.5
0.1％
0.4％
1％

Heat transfer coefficient ratio

Re=6000

Enhancement of Heat Transfer

Xuan and Li :Turbulent flow regime.
z

1.25

Wen and Ding :The entrance region in thelaminar flow regime.
z1
Pure water

100200
X/D

Streamwise variation of local heat transfer fordifferent particle concentrations (Nano-diamond)結果と考察 [伝熱性能]

Nu =hDNu =k)

f = [1.82 log 10 (Re ) − 1.64]−2NuCuOナノ流体についてはNuが減少(

1.07 + 12.7 f 8 Pr 2 3 − 1

Al2O3 1％
CuO 1％
Diamond 1％
Water
Gnielinski

60

熱伝導率よりも熱伝達率の向上率の方が大きい( f 8)(Re − 1000)Pr40

粒子の凝縮が原因？
4000

6000
Re

8000

Nusselt numbers of water and nanofluids

現在実験中の結果
5 vol.％ CuO
0.1 vol.％ CuO
GnielinskiNu60

5 vol.％ Al2O30.1 vol.％ Al2O31 vol.％ Diamond
Water

40

4000

6000
Re

8000

Nusselt numbers of water and nanofluids with different volume fractions

結言①ナノ流体の粘度はBatchelorの式で算定することができない。
②圧力損失は単相流と比較して大きい。
③ナノ流体は単相流と比較して優れた伝熱性能を示した。ナノ流体によっては、単相流に比べて伝熱性能が低下する傾向が見られた。これに対しては更なる考察と研究は必要。

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