The effects of viscous dissipation on the entropy generation of water–alumina nanofluid convection in circular microchannels subjected to exponential wall heat flux are investigated. Closed-form solutions of the temperature distributions in the streamwise direction are obtained for the models with and without viscous dissipation term in the energy equation. The two models are compared by analyzing their relative deviations in entropy generation for different Reynolds numbers and nanoparticle volume fractions. The incorporation of viscous dissipation prominently affects the temperature distribution and consequently the entropy generation. When the viscous dissipation effect is neglected, the total entropy generation and the fluid friction irreversibility are nearly twofold overrated while the heat transfer irreversibility is underestimated significantly. By considering the viscous dissipation effect, the exergetic effectiveness for forced convection of nanofluid in microchannels attenuates with the increasing nanoparticle volume fraction and nanoparticle diameter. The increase in the entropy generation of nanofluid is mainly attributed to the intensification of fluid friction irreversibility. From the aspect of the second-law of thermodynamics, the widespread conjecture that nanofluids possess advantage over pure fluid associated with higher overall effectiveness is invalidated.

References

References
1.
Lee
,
J.
, and
Mudawar
,
I.
,
2007
, “
Assessment of the Effectiveness of Nanofluids for Single-Phase and Two-Phase Heat Transfer in Micro-Channels
,”
Int. J. Heat Mass Transfer
,
50
(
3–4
), pp.
452
463
.
2.
Hussein
,
A. M.
,
Sharma
,
K. V.
,
Bakar
,
R. A.
, and
Kadirgama
,
K.
,
2014
, “
A Review of Forced Convection Heat Transfer Enhancement and Hydrodynamic Characteristics of a Nanofluid
,”
Renewable Sustainable Energy Rev.
,
29
, pp.
734
743
.
3.
Ting
,
T. W.
,
Hung
,
Y. M.
, and
Guo
,
N.
,
2014
, “
Viscous Dissipative Forced Convection in Thermal Non-Equilibrium Nanofluid-Saturated Porous Media Embedded in Microchannels
,”
Int. Commun. Heat Mass Transfer
,
57
, pp.
309
318
.
4.
Vajjha
,
R. S.
, and
Das
,
D. K.
,
2009
, “
Experimental Determination of Thermal Conductivity of Three Nanofluids and Development of New Correlations
,”
Int. J. Heat Mass Transfer
,
52
(
21–22
), pp.
4675
4682
.
5.
Murshed
,
S. M. S.
,
Leong
,
K. C.
, and
Yang
,
C.
,
2008
, “
Thermophysical and Electrokinetic Properties of Nanofluids—A Critical Review
,”
Appl. Therm. Eng.
,
28
(
17–18
), pp.
2109
2125
.
6.
Bejan
,
A.
,
1996
,
Entropy Generation Minimization: The Method of Thermodynamic Optimization of Finite-Size Systems and Finite-Time Processes
,
CRC Press
, Boca Raton, FL.
7.
Hung
,
Y. M.
,
2008
, “
Viscous Dissipation Effect on Entropy Generation for Non-Newtonian Fluids in Microchannels
,”
Int. Commun. Heat Mass Transfer
,
35
(
9
), pp.
1125
1129
.
8.
Hung
,
Y. M.
,
2009
, “
A Comparative Study of Viscous Dissipation Effect on Entropy Generation in Single-Phase Liquid Flow in Microchannels
,”
Int. J. Therm. Sci.
,
48
(
5
), pp.
1026
1035
.
9.
Sciacovelli
,
A.
, and
Verda
,
V.
,
2010
, “
Entropy Generation Minimization in a Tubular Solid Oxide Fuel Cell
,”
ASME J. Energy Resour. Technol.
,
132
(
1
), p.
012601
.
10.
Shamshiri
,
M.
,
Khazaeli
,
R.
,
Ashrafizaadeh
,
M.
, and
Mortazavi
,
S.
,
2012
, “
Heat Transfer and Entropy Generation Analyses Associated With Mixed Electrokinetically Induced and Pressure-Driven Power-Law Microflows
,”
Energy
,
42
(
1
), pp.
157
169
.
11.
Matin
,
M. H.
, and
Khan
,
W. A.
,
2013
, “
Entropy Generation Analysis of Heat and Mass Transfer in Mixed Electrokinetically and Pressure Driven Flow Through a Slit Microchannel
,”
Energy
,
56
, pp.
207
217
.
12.
Safari
,
M.
, and
Sheikhi
,
M. R. H.
,
2014
, “
Large Eddy Simulation for Prediction of Entropy Generation in a Nonpremixed Turbulent Jet Flame
,”
ASME J. Energy Resour. Technol.
,
136
(
2
), p.
022002
.
13.
Ting
,
T. W.
,
Hung
,
Y. M.
, and
Guo
,
N.
,
2014
, “
Entropy Generation of Nanofluid Flow With Streamwise Conduction in Microchannels
,”
Energy
,
64
, pp.
979
990
.
14.
Ting
,
T. W.
,
Hung
,
Y. M.
, and
Guo
,
N.
,
2014
, “
Effects of Streamwise Conduction on Thermal Performance of Nanofluid Flow in Microchannel Heat Sinks
,”
Energy Convers. Manage.
,
78
, pp.
14
23
.
15.
Mahian
,
O.
,
Mahmud
,
S.
, and
Heris
,
S. Z.
,
2012
, “
Analysis of Entropy Generation Between Co-Rotating Cylinders Using Nanofluids
,”
Energy
,
44
(
1
), pp.
438
446
.
16.
Moghaddami
,
M.
,
Mohammadzade
,
A.
, and
Esfehani
,
S. A. V.
,
2011
, “
Second Law Analysis of Nanofluid Flow
,”
Energy Convers. Manage.
,
52
(
2
), pp.
1397
1405
.
17.
Feng
,
Y.
, and
Kleinstreuer
,
C.
,
2010
, “
Nanofluid Convective Heat Transfer in a Parallel-Disk System
,”
Int. J. Heat Mass Transfer
,
53
(
21–22
), pp.
4619
4628
.
18.
Li
,
J.
, and
Kleinstreuer
,
C.
,
2010
, “
Entropy Generation Analysis for Nanofluid Flow in Microchannels
,”
ASME J. Heat Transfer
,
132
(
12
), p.
122401
.
19.
Shalchi-Tabrizi
,
A.
, and
Seyf
,
H. R.
,
2012
, “
Analysis of Entropy Generation and Convective Heat Transfer of Al2O3 Nanofluid Flow in a Tangential Micro Heat Sink
,”
Int. J. Heat Mass Transfer
,
55
(
15–16
), pp.
4366
4375
.
20.
Sarkar
,
S.
,
Ganguly
,
S.
, and
Dalal
,
A.
,
2012
, “
Analysis of Entropy Generation During Mixed Convective Heat Transfer of Nanofluids Past a Square Cylinder in Vertically Upward Flow
,”
ASME J. Heat Transfer
,
134
(
12
), p.
122501
.
21.
Feng
,
Y.
, and
Kleinstreuer
,
C.
,
2012
, “
Thermal Nanofluid Property Model With Application to Nanofluid Flow in a Parallel Disk System—Part II: Nanofluid Flow Between Parallel Disks
,”
ASME J. Heat Transfer
,
134
(
5
), p.
051003
.
22.
Mohammadian
,
S. K.
,
Reza Seyf
,
H.
, and
Zhang
,
Y.
,
2013
, “
Performance Augmentation and Optimization of Aluminum Oxide-Water Nanofluid Flow in a Two-Fluid Microchannel Heat Exchanger
,”
ASME J. Heat Transfer
,
136
(
2
), p.
021701
.
23.
Koo
,
J.
, and
Kleinstreuer
,
C.
,
2004
, “
Viscous Dissipation Effects in Microtubes and Microchannels
,”
Int. J. Heat Mass Transfer
,
47
(
14–16
), pp.
3159
3169
.
24.
Hung
,
Y. M.
,
2010
, “
Analytical Study on Forced Convection of Nanofluids With Viscous Dissipation in Microchannels
,”
Heat Transfer Eng.
,
31
(
14
), pp.
1184
1192
.
25.
Mah
,
W. H.
,
Hung
,
Y. M.
, and
Guo
,
N.
,
2012
, “
Entropy Generation of Viscous Dissipative Nanofluid Flow in Microchannels
,”
Int. J. Heat Mass Transfer
,
55
(
15–16
), pp.
4169
4182
.
26.
Prasher
,
R.
,
Bhattacharya
,
P.
, and
Phelan
,
P. E.
,
2005
, “
Thermal Conductivity of Nanoscale Colloidal Solutions (Nanofluids)
,”
Phys. Rev. Lett.
,
94
(
2
), p.
025901
.
27.
Buongiorno
,
J.
,
2006
, “
Convective Transport in Nanofluids
,”
ASME J. Heat Transfer
,
128
(
3
), pp.
240
250
.
28.
Anoop
,
K. B.
,
Kabelac
,
S.
,
Sundararajan
,
T.
, and
Das
,
S. K.
,
2009
, “
Rheological and Flow Characteristics of Nanofluids: Influence of Electroviscous Effects and Particle Agglomeration
,”
J. Appl. Phys.
,
106
(
3
), p.
034909
.
29.
Jang
,
S. P.
,
Lee
,
J.-H.
,
Hwang
,
K. S.
, and
Choi
,
S. U. S.
,
2007
, “
Particle Concentration and Tube Size Dependence of Viscosities of Al2O3-Water Nanofluids Flowing Through Micro- and Minitubes
,”
Appl. Phys. Lett.
,
91
(
24
), p.
243112
.
30.
Singh
,
P. K.
,
Anoop
,
K. B.
,
Sundararajan
,
T.
, and
Das
,
S. K.
,
2010
, “
Entropy Generation Due to Flow and Heat Transfer in Nanofluids
,”
Int. J. Heat Mass Transfer
,
53
(
21–22
), pp.
4757
4767
.
31.
Bergman
,
T. L.
,
2009
, “
Effect of Reduced Specific Heats of Nanofluids on Single Phase, Laminar Internal Forced Convection
,”
Int. J. Heat Mass Transfer
,
52
(
5–6
), pp.
1240
1244
.
32.
Gad-el-Hak
,
M.
,
1999
, “
The Fluid Mechanics of Microdevices—The Freeman Scholar Lecture
,”
ASME J. Fluids Eng.
,
121
(
1
), pp.
5
33
.
33.
Wang
,
X.
,
Xu
,
X.
, and
Choi
,
S. U. S.
,
1999
, “
Thermal Conductivity of Nanoparticle-Fluid Mixture
,”
J. Thermophys. Heat Transfer
,
13
(
4
), pp.
474
480
.
34.
Guo
,
S. Z.
,
Li
,
Y.
,
Jiang
,
J. S.
, and
Xie
,
H. Q.
,
2010
, “
Nanofluids Containing γ-Fe2O3 Nanoparticles and Their Heat Transfer Enhancements
,”
Nanoscale Res. Lett.
,
5
(
7
), pp.
1222
1227
.
35.
Hall
,
W. B.
,
Jackson
,
J. D.
, and
Price
,
P. H.
,
1963
, “
Note on Forced Convection in a Pipe Having a Heat Flux Which Varies Exponentially Along Its Length
,”
J. Mech. Eng. Sci.
,
5
(
1
), pp.
48
52
.
36.
Sparrow
,
E. M.
, and
Patankar
,
S. V.
,
1977
, “
Relationships Among Boundary Conditions and Nusselt Numbers for Thermally Developed Duct Flows
,”
ASME J. Heat Transfer
,
99
(
3
), pp.
483
485
.
37.
Barletta
,
A.
, and
Zanchini
,
E.
,
1995
, “
On the Laminar Forced Convection With Axial Conduction in a Circular Tube With Exponential Wall Heat Flux
,”
Heat Mass Transfer
,
30
(
5
), pp.
283
290
.
38.
Maranzana
,
G.
,
Perry
,
I.
, and
Maillet
,
D.
,
2004
, “
Mini- and Micro-Channels: Influence of Axial Conduction in the Walls
,”
Int. J. Heat Mass Transfer
,
47
(
17–18
), pp.
3993
4004
.
39.
Hung
,
Y. M.
, and
Tio
,
K. K.
,
2010
, “
Analysis of Microheat Pipes With Axial Conduction in the Solid Wall
,”
ASME J. Heat Transfer
,
132
(
7
), p.
071301
.
40.
Hetsroni
,
G.
,
Mosyak
,
A.
,
Pogrebnyak
,
E.
, and
Yarin
,
L. P.
,
2005
, “
Heat Transfer in Micro-Channels: Comparison of Experiments With Theory and Numerical Results
,”
Int. J. Heat Mass Transfer
,
48
(
25–26
), pp.
5580
5601
.
41.
Bergman
,
T. L.
,
Lavine
,
A. S.
,
DeWitt
,
D. P.
, and
Incropera
,
F. P.
,
2011
,
Introduction to Heat Transfer
,
Wiley
,
New York
.
42.
Asadi
,
M.
,
Xie
,
G.
, and
Sunden
,
B.
,
2014
, “
A Review of Heat Transfer and Pressure Drop Characteristics of Single and Two-Phase Microchannels
,”
Int. J. Heat Mass Transfer
,
79
, pp.
34
53
.
43.
Kadam
,
S. T.
, and
Kumar
,
R.
,
2014
, “
Twenty First Century Cooling Solution: Microchannel Heat Sinks
,”
Int. J. Therm. Sci.
,
85
, pp.
73
92
.
44.
Green
,
D.
, and
Perry
,
R.
,
2007
,
Perry's Chemical Engineers' Handbook
,
McGraw-Hill
,
New York
.
You do not currently have access to this content.