T. GANESAN, P. SEENI KANNAN: HEAT-TRANSFER ENHANCEMENT OF NANOFLUIDS IN A CAR RADIATOR
507–512
HEAT-TRANSFER ENHANCEMENT OF NANOFLUIDS IN A CAR
RADIATOR
IZBOLJ[ANJE PRENOSA TOPLOTE NANOTEKO^IN V
AVTOMOBILSKEM RADIATORJU
Thangasamy Ganesan
1
, Pauldurai Seeni Kannan
2
1
Department of Mechanical Engineering, AR College of Engineering & Technology, Kadayam, Tamilnadu 627 423, India
2
Department of Mechanical Engineering, AAA College of Engineering and Technology, Sivakasi, Tamilnadu 626 123, India
ganesanjoshi2012@gmail.com
Prejem rokopisa – received: 2017-10-07; sprejem za objavo – accepted for publication: 2018-02-22
doi:10.17222/mit.2017.171
In recent times, enhancing the efficiency of automobiles has become very important. As part of this effort, increasing the
efficiency of the heat transfer in the radiator of an automobile is also crucial. The present approach involves an addition of
nanoparticles to the cooling liquid. Most of the current results were obtained using a few types of nanoparticles. Only a limited
amount of work involved hybrid nanofluids including several types of nanoparticles. Multi-walled carbon nanotubes (MWCNT)
were used along with aluminium-oxide nanoparticles to form a nanofluid with the base fluid (ethylene glycol (EG) + distilled
water (DW) – 1:1 ratio) having volume concentrations of (0.03, 0.06, 0.09 and 0.12) %. The characterization of the
nanoparticles was carried out. The experiments were carried out at inlet temperatures of 40–75 °C, with increments of 5 °C. The
volume flow rate was varied from 0.6 m
3
/h to 0.96 m
3
/h, with increments of 0.12 m
3
/h. An increase in the heat transfer of 35 %
was achieved.
Keywords: computational fluid dynamics, nanofluids, alumina, multi-walled carbon nanotubes
V zadnjem ~asu je postalo zelo pomembno pove~anje zmogljivosti avtomobilov, hkrati s tem pa tudi pove~anje u~inkovitosti
prenosa toplote v avtomobilskih radiatorjih. V prispevku so avtorji dodali nanodelce v hladilno sredstvo (kapljevino). Ve~ina
podanih rezultatov se nana{a na uporabo nekaj razli~nih vrst nanodelcev. Delno pa so avtorji raziskovali tudi hibridna hladilna
sredstva oziroma vpliv isto~asnega dodatka ve~ razli~nih vrst nanodelcev. Uporabili so dodatek ve~stenskih ogljikovih nanocevk
(MWCNT; angl.: Multi Walled Carbon Nano Tubes) v kombinaciji z nanodelci Al oksida k osnovnemu hladilnemu sredstvu
(Etilen Glikol (EG) + destilirana voda (DW) – v razmerju 1:1) v volumskih koncentracijah (0,03, 0,06, 0,09 and 0,12) %. Izvedli
so karakterizacijo nanodelcev. Preizkuse so izvajali pri vstopnih temperaturah hladilnega sredstva od 40 °C do 75 °C v korakih
po 5 °C. Hitrost volumskega pretoka je varirala od 0,6 m
3
/h do 0,96 m
3
/h v korakih po 0,12 m
3
/h. Dosegli so pove~anje prenosa
toplote do 35 %.
Klju~ne besede: ra~unalni{ka dinamika teko~in (kapljevin in plinov), nanoteko~ine, aluminijev oksid, ve~stenske ogljikove
nanocevke
1 INTRODUCTION
Only a part of the heat energy produced with com-
bustion is converted to the mechanical energy to power
the automobiles while the remaining energy is rejected
and unutilized. A part of the energy is removed by the
cooling water surrounding the engine and then taken to
the radiator while the heat is released into the atmo-
sphere. If effective cooling is not done, the efficiency of
the engine can be reduced and, in extreme cases, engine
may be damaged by overheating. The cooling system
normally consists of a cooling medium surrounding the
engine cylinder, a pump allowing the circulation of the
cooling medium, a radiator with a cooling fan and a
thermostat. In the present work, an attempt to improve
the effectiveness of the heat transfer in the radiator was
made. With the advances made in the field of nanotech-
nology, we now have nanoparticles, which can be mixed
with the fluid to form a homogeneous mixture. These
mixtures are called nanofluids and they have better
thermal properties. They enhance the heat transfer even
with a low concentration of nanoparticles. The papers
published so far indicate improvement in the heat
transfer due to single nanoparticles. Further research can
be done using hybrid nanofluids, which are mixtures of
more than one type of nanoparticles. It is expected that
hybrid nanofluids will improve the heat transfer.
2 LITERATURE SURVEY
A brief survey of the work done so far is presented
below.
K. S Suganthi et al.
1
prepared a nanofluid using a
spherical ZnO by mixing it with water and propylene
glycol (PG). The heat-absorption capacity of their nano-
fluid was compared with that of the solution of just water
and PG. The nanofluid showed a higher heat absorption
capacity than the solution of water and PG. The
nanofluid showed an increase of 16 % in the case of heat
transfer under indicator conditions with2%v olume of
ZnO of 70 nm. B. Ilhan et al.
2
used hexagonal boron ni-
tride (HBN) to make a nanofluid using a volume con-
Materiali in tehnologije / Materials and technology 52 (2018) 4, 507–512 507
UDK 629.331:62-714:536.2:620.3 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 52(4)507(2018)

centration of 0.03–0.3 % to make nano sodium dodecyl
sulphate (SDS) and polyvinyl pyrrolidon was used as the
surfactant. The HBN nanofluild had a higher thermal
conductivity compared to the base fluid. M. A. A. Beha-
badi et al.
3
conducted experiments using multi-walled
carbon nanotubes (MWCNT). They were mixed with
water with weight concentrations of 0.05, 0.1 and 0.2.
The MWCNT nanofluid showed an enhanced heat-trans-
fer rate. The pressure drop in this case was higher than
that of the base fluid. W. H. Azmi et al.
4
compared the
performance of a water-based nanofluid and ethylene-
glycol water-based nanofluid. The water-based nanofluid
showed a higher heat-transfer rate. M. B. Bigdeli et al.
5
carried out a study of thermophysical properties of a
nanofluid. The study shows the nanofluid having better
thermal properties than the base fluids. However, the
details of the concentration and size of the nanoparticles
were not reported. M. Tamizi et al.
6
studied the thermo-
physical properties of a nanofluid with different volume
fractions. It was shown that the heat-transfer rate was
higher for a higher volume fraction. S. Suresh et al.
7
used
a hybrid nanofluid in their study. The nanofluid was
made with the nanoparticles of aluminium oxide and
copper. The experiment showed an improvement of 25 %
for the heat transfer compared to the base fluid. D. Mad-
hesh et al.
8
used copper and titanium nanoparticles with
volume concentrations varying from 0.1 % to 1 % in a
radiator and heat-transfer rates increased by up to 48.5 %
were attained. N. Bozorgan et al.
9
conducted a numerical
investigation of Al
2
O
3
nanoparticles with water as the
base fluid using empirical relations to determine the
properties such as density, viscosity, specific heat and
thermal conductivity. G. Huminic et al.
10
also studied the
thermal properties of a nanofluid and found the heat-
transfer rate increasing with an addition of nanoparticles.
3. EXPERIMENTAL PART
Figure 1 shows a diagram of the experimental set-up
and Figure 2 includes a photograph of the set-up.
The set-up included the radiator from a Maruthi Alto
car. The engine had the power of 85 BHP. There were
also the cooling fan, the water tank, the heater, and the
control for the heater used to maintain the temperature of
the inlet of the water, which was constant for the com-
ponents in the set-up. Instruments for measuring the
temperature of the water at the inlet and outlet were
provided. Two additional thermocouples were provided
to measure the temperature of the air, flowing across the
radiator. They were fixed to the air inlet and outlet of the
radiator.
A gate valve was provided to regulate the flow of the
water through the radiator. Three heater controllers were
provided to heat the water to be sent to the radiator to the
steady state temperature of the inlet. The radiator was
placed inside a duct and a fan was used to provide the
flow at two different speeds. Experiments were carried
out for different flow rates of 0.6 m
3
/h and 0.96 m
3
/h
with increments of 0.12 m
3
/h. The temperature of the
cooling fluid at the inlet was varied from 40 °C to 75 °C.
The thermocouple used to measure the temperature had
an accuracy of ±0.5 °C. A pump of 0.5 HP was used to
circulate the cooling fluid from the storage tank. An
T. GANESAN, P. SEENI KANNAN: HEAT-TRANSFER ENHANCEMENT OF NANOFLUIDS IN A CAR RADIATOR
508 Materiali in tehnologije / Materials and technology 52 (2018) 4, 507–512
Figure 2: Experimental set-up photograph
Figure 1: Circuit diagram of the experimental set-up
Table 1: Experimental set-up specifications
Radiator
Width: 370 mm; Height: 400 mm; Tube size: 20
× 2 mm; Fin thickness: 1 mm; Fin pitch: 1 mm
Tank
Capacity: 14 l; Material: stainless steel;
Diameter: 260 mm; Height: 300 mm
Heater
Type: Epson; Number of heaters: 3; Power:
2 kW; Thermostat: range of 0–75 °C (Girsheg);
Accuracy: ±0.5 °C
Pump
Made by CRI; Capacity: 0.5 hp; Speed:
2800 min
–1
; Water capacity: 1080 l/hr
Thermo-
meter
Type: digital; Make: Nanotech; Range:
0–400 °C; Accuracy: ±0.5 °C
Fan
Power: 80 W (motor); Number of speed rates:
2; Diameter: 400 mm; Number of blades: 6;
Type of blade: curved
Rotameter
Make: Acrylic; Type: micro; Capacity: 0.6–6
m
3
/h
Anemo-
meter
Model: AVM 06; Display: LCD; Make: BEE
Tech-Max; Show value: 9999; Accuracy: ±
(2.0 % reading + 50 characters)
Hose
Type: rubber; Length: 1552.5 mm (radiator to
tank: 900 mm, tank to pump: 450 mm,
rotameter to radiator: 202.5 mm)

anemometer was used to measure the velocity of the air
through the duct. Readings were taken at four points and
the operating average velocity was calculated. Table 1
shows the specifications of the experimental set-up for
this work.
3.1 Experimental procedure
The system was first cleaned thoroughly. Then the
tank was filled with distilled water. A test run was done
to ensure that the water circuit had no leakages. Then the
heaters were switched on for the water to reach the
required temperature. After that, the heating elements
were controlled by the temperature controller to maintain
a steady temperature. The water pump was switched on.
After that, the radiator fan was switched on and we
waited until steady-state conditions were reached and all
the readings were taken. The temperatures at the outlet
and inlet of the water and air were measured. The
velocity of the air was also measured. The experiment
was repeated for water-flow rates of (0.72, 0.84 and
0.96) m
3
/h. For the second set of experiments, a mixture
of water and ethylene glycol with a ratio of 1:1 was used.
The experiments were then conducted using nanofluids
with volume concentrations of 0.03–0.12 %, with incre-
ments of 0.03 %.
3.2 Nanofluid characterization
The characterization of nanofluids was done by eva-
luating the XRD test shown in Figures 3a and 3b. The
Sheerin formula was used to calculate the nanoparticle
size, which was 40 nm.
The precipitate formed was washed with distilled
water and dried. SEM images of the prepared sample are
shown in Figures 4 and 5. A nanofluid with the required
volume concentration was then prepared by dispersing a
specified amount of Al
2
O
3
nanoparticles in water using
an ultrasonic vibrator (Toshiba, India) generating ultra-
sonic pulses of 100 W at 36±3 kHz. To get a uniform
dispersion and stable suspension, which determine the
final properties of nanofluids, the nanofluids were kept
under ultrasonic vibration continuously for 9 h. No
surfactant or pH changes were used as they may have
some influence on the effective thermal conductivity of
nanofluids. The pH values of the prepared nanofluids
with different concentrations were measured and found
to be around 5, which is far from the isoelectric point of
9.2 for alumina nanoparticles. This value, being far from
the isoelectric point, ensures that the nanoparticles are
well dispersed and the nanofluid is stable because of
very large repulsive forces among the nanoparticles.
3.3 Prepartion of Al
2
O
3
/multi-walled carbon nanofluids
The nanoparticles were purchased from Alfa Aesar,
USA. The Al
2
O
3
nanoparticle MWCNTs were tested
with a Zetasizer machine for measuring the particle size,
T. GANESAN, P. SEENI KANNAN: HEAT-TRANSFER ENHANCEMENT OF NANOFLUIDS IN A CAR RADIATOR
Materiali in tehnologije / Materials and technology 52 (2018) 4, 507–512 509
Figure 5: SEM image of MWCNT
Figure 3: XRD test result for: a) Al
2
O
3
, b) MWCNT
Figure 4: SEM test report for Al
2
O
3

from Horibon, Japan. The machine is shown in Figure 6.
The nanofluids were prepared as per volume concen-
tration. Then a magnetic stirrer and an ultrasonicator
were used to mix them without any sedimentation as
shown below. The characteristics of aluminium are given
in Table 2.
Table 2: Properties of the nanoparticles
S. no. Properties Al 2O 3 MWCNT
1. Purity (%) 99.99 99.9
2.
Approximate
size (nm)
50 60
3. Color White Black
4. Morphology Nearly spherical Tubes
5. Density (g/cm
3
) 3.428 1.4
Next, an ultra-violet (UV) test was carried out to
check whether the nanofluids were without any sedimen-
tation. No sediment was identified. Figure 7 clearly
indicates that the nanofluids contained only the base
fluid.
4 RESULTS AND DISCUSSION
Nanofluids with various volume concentrations were
prepared. Then they were tested with the experimental
set-up and the readings were taken. The thermal
properties of various samples were tested and the results
are shown below.
4.1 Analysis of thermal properties
4.1.1 Measurement of viscosity values
The viscosity of the nanofluids was measured using a
Brookfield cone and plate viscometer (DV-E Visco-
meter), supplied by Brookfield Engineering Labora-
tories, USA, as shown in Figure 8. The device is
switched off before attaching the spindle. The spindle
speeds available with this viscometer are in a range of
0–100 min
–1
and the shear-rate range is 0–750 s. Then
the spindle is immersed in the center of the test material
so that the fluid’s level is at the immersion groove on the
spindle’s shaft. With a disc-type spindle, it is sometimes
necessary to tilt the spindle slightly while immersing it
to avoid trapping air bubbles on its surface. To make a
viscosity measurement, a speed of 12 min
–1
is selected.
The maximum time allows the indicated reading to
stabilize. The time required for its stabilization depends
on the speed of the viscometer and the characteristics of
the sample fluid. Now the device is switched off and the
sample is replaced by a new one. A minimum of three
measurements were made for each test sample. Then the
average value was taken. Each sample constituted of a
20-ml solution. Table 3 shows the values of the viscosity
for all the samples.
Table 3: Viscosity values for the samples
S. No. Name of the sample Viscosity (cP)
1. 0.03 % hybrid nanofluid 23.5
2. 0.06 % hybrid nanofluid 20.5
3. 0.09 % hybrid nanofluid 22.5
4. 0.12 % hybrid nanofluid 20.5
5. EG+DW (1:1 ratio) 18.5
6. DW 1.5
For the 0.03 % sample, the thermal conductivity
increases by 5 % where the heat transfer at a higher tem-
perature is considered to be the molecular-level diffe-
rence of the sample. At the mean time for the 0.06 %
sample, the thermal conductivity increases by 11 %. It is
concluded that with the increasing volume concentration
of nanofluids, the heat transfer also increases. Thus, at
the 0.12 % volume concentration of nanofluids, a high
heat-transfer rate is achieved. It is also concluded that
with the hybrid nanofluids containing the base fluids, a
high heat-transfer rate is achieved. With the increasing
volume concentration of nanofluids, there is also a
chance for pumping. This issue requires further research.
T. GANESAN, P. SEENI KANNAN: HEAT-TRANSFER ENHANCEMENT OF NANOFLUIDS IN A CAR RADIATOR
510 Materiali in tehnologije / Materials and technology 52 (2018) 4, 507–512
Figure 8: Viscometer
Figure 6: (a) Magnetic stirrer, (b) ultrasonicator
Figure 7: UV spectroscopy result

4.1.2 Thermal-conductivity measurement
The compact KD2 Pro controller is much more than a
simple readout for time and temperature as shown in
Figure 9. A proprietary algorithm fits the time and
temperature data with experimental integral functions
using a nonlinear least squares method. This fully ma-
thematical solution delivers thermal conductivity to
within ±10 %. The ASTM standard D5334 and IEEE
standard 442-1981 are followed. All the samples were
characterized at room temperature. The KD2 Pro was
configured in the low-power mode with a 1-minute read
time to prevent free convection in the fluid test samples.
The accuracy of the KS-1 sensor and the associated
KD-2 Pro unit was verified using the glycerol verifica-
tion standard immediately before the measurements
made on the test samples. A minimum of three measure-
ments was made for each test sample. Before the
beginning of each measurement, the vial with the mate-
rial was vigorously shaken until all the nanoparticles
were in the suspension and then the shaking continued
for at least 60 additional seconds to ensure that the
sample was well dispersed and fully suspended. The
accuracy and range repeatability of this instrument are
±1 % and ±0.2 %, respectively. The thermal conductivity
of all six samples measured using a 0.40 mL solution for
each sample is shown in Table 4.
Table 4: Thermal-conductivity values for the samples
S. no Name of the sample
Temperature
(°C)
Thermal
conductivity
(W/mK)
1. 0.03 % hybrid nanofluid 28.75 0.579
2. 0.06 % hybrid nanofluid 28.72 0.551
3. 0.09 % hybrid nanofluid 28.68 0.585
4. 0.12 % hybrid nanofluid 29.19 0.570
5. EG+DW (1:1 ratio) 28.7 0.569
6. DW 29.04 0.529
4.2 Uncertainity analysis
Experimental uncertainties were calculated using the
method developed by Kline and McClintock. This
method incorporates the estimated uncertainties of the
experimental measurements such as the water-inlet tem-
perature, water-outlet temperature and water-mass-flow
rate in the experiment. These are then compared with the
final parameters of the heat-transfer rate and the calcul-
ated Reynolds number. Using the measured uncertainties
of the above-mentioned parameters, the maximum
calculated uncertainties for the heat-transfer rate were
found to be 10 % and 9.7 % for pure water and the nano-
fluids, respectively. The fluid-mass-flow rate participated
significantly to the calculated uncertainty, especially in
the case of the nanofluids. The maximum uncertainty of
the calculated Reynolds number was found to be 2.8 %
for all the cases.
4.3 Computational-fulid-dynamics analysis (CFD)
The heat transfer rate was also measured using the
computational-fluid-dynamics (CFD) software. Its re-
sults were also compared with the experimental results.
It is shown that the results for the increasing heat transfer
in the experimental set-up were higher than those of the
CFD analysis. In Figure 10, for the 0.09 % Al
2
O
3
+1%
MWNCT nanofluid, the CFD analysis shows that a small
increment in the heat-transfer rate of 19 kW is obtained
at the given mass-flow rate (0.6 m
3
/hr) and the tempera-
ture of 40 °C. For the temperature of 70 °C and the
0.96 m
3
/h mass-flow rate, the maximum heat-transfer
rate of 56 kW is obtained with the CFD analysis. It is
observed that while adding 1 % MWNCT with the Al
2
O
3
nanofluids, the heat-transfer rate increases by 26 %
according to the CFD analysis.
Figure 11 shows the heat-transfer rate at the 0.6 m
3
/h
mass-flow rate for pure distilled water, 1 % MWNCT
and 1.5 % MWNCT with distilled water, 0.09 % Al
2
O
3
nanofluids with1%M W N C Ta n d1 . 5%M W N C T .
From this graph, it is clear that the heat-transfer rate of
the 0.09 % Al
2
O
3
nanofluid is followed by those of 1 %
T. GANESAN, P. SEENI KANNAN: HEAT-TRANSFER ENHANCEMENT OF NANOFLUIDS IN A CAR RADIATOR
Materiali in tehnologije / Materials and technology 52 (2018) 4, 507–512 511
Figure 10: CFD analysis for 0.09 % Al
2
O
3
with 1 % MWCNT Figure 9: Thermal-conductivity instrument

MWNCT and 1.5 % MWNCT. While considering the
comparison with the CFD analysis, we observe a high
heat-transfer rate.
5 CONCLUSIONS
Experimental and CFD analyses were done. The
MWCNT was added together with 0.09 % Al
2
O
3
nano-
fluids. The input temperature varied between (40, 45, 50,
55, 60, 65 and 70) °C. The mass-flow rate varied bet-
ween (0.6, 0.72, 0.84 and 0.96) m
3
/h, respectively. It was
concluded that when adding (0.5, 1 and 1.5) % MWCNT
together with the nanofluids, increased heat-transfer
rates were obtained. According to the CFD analysis, with
the 0.5 % MWCNT + 0.09 % Al
2
O
3
nanofluid, the heat-
transfer rate increased by 3.31 %; with 1% MWCNT +
0.09 % Al
2
O
3
, the heat-transfer rate increased by 8.96 %;
and, similarly, when 1.5 % MWCNT was added together
with the Al
2
O
3
nanofluid, an increase in the heat-transfer
rate of 13.814 % was obtained. In the case of the expe-
rimental analysis, when adding 0.5 % MWCNT together
with the 0.09 % Al
2
O
3
nanofluids, the maximum increase
in the heat transfer rate of 16 % was obtained at a mass-
flow rate of 0.96 m
3
/h. With the addition of 1 %
MWCNT and 0.09 % Al
2
O
3
nanofluid, the heat-transfer
rate increased by 34 %. Similarly, for 1.5 % MWCNT
and 0.09 % Al
2
O
3
nanofluid, the heat-transfer rate in-
creased by 35 %. It was proven that MWCNT signifi-
cantly improved the heat transfer when added together
with the Al
2
O
3
nanofluids.
6 REFERENCES
1
K. S. Suganthi, V. Leela Vinodhan, K. S. Rajan, ZnO-Propylene
Glycol-Water Nanofluids with Improved Properties for Potential
Applications in Renewable Energy and Thermal Management,
Colloids and Surfaces A: Physicochemical and Engineering Aspects,
506 (2016) 5, 63–73, doi:10.1016/j.colsurfa.2016.06.007
2
B. Ilhan, M. Kurt, H. Ertürk, Experimental investigation of heat
transfer enhancement and viscosity change of hBN nanofluids,
Experimental Thermal and Fluid Science, 77 (2016), 272–283,
doi:10.1016/j.expthermflusci.2016.04.024
3
M. A. A Behabadi, M. Shahidi, M. R. Aligoodarz, M. Fakoor, An
experimental investigation on rheological properties and heat transfer
performance of MWCNT-water nanofluid flow inside vertical tubes,
Applied Thermal Engineering, 106 (2016) 5, 916–924,
doi:10.1016/j.applthermaleng.2016.06.076
4
W. H. Azmi, K. Abdul Hamid, N. A. Usri, R. Mamat, K. V. Sharma,
Heat transfer augmentation of ethylene glycol: water nanofluids and
applications–Are vie w ,International Communications in Heat and
Mass Transfer, 75 (2016), 13–23, doi:10.1016/j.icheatmasstransfer.
2016.03.018
5
M. B. Bigdeli, M. Fasano, A. Cardellini, E. Chiavazzo, P. Asinari, A
review on the heat and mass transfer phenomena in nanofluid
coolants with special focus on automotive applications, 60 (2016),
1615–1633, doi:10.1016/j.rser.2016.03.027
6
M. Tamizi, M. Kamalv, M. Namazian, Dependency of the thermo-
physical properties of nanofluids on the excess adsorption, Inter-
national Journal of Heat and Mass Transfer, 99 (2016), 630–637,
doi:10.1016/j.ijheatmasstransfer.2016.04.029
7
S. Suresh, K. P. Venkitaraj, P. Selvakumar, M. Chandrasekar, Effect
of Al2O3–Cu/water hybrid nanofluid in heat transfer, Experimental
Thermal and Fluid Science, 38 (2012), 54–60, doi:10.1016/
j.expthermflusci.2011.11.007
8
D. Madhesh, S. Kalaiselvam, Experimental Analysis of Hybrid
Nanofluid as a Coolant, Procedia Engineering, 97 (2014),
1667–1675, doi:10.1016/j.proeng.2014.12.317
9
N. Bozorgan, K. Krishnakumar, N. Bozorganv, The Performance
Evaluation of Overall Heat Transfer and Pumping Power of -Al2O3/
water Nanofluid as Coolant in Automotive Diesel Engine Radiator,
Analele Universitãlii "Eftimie Murgu" Resita, 1 (2013)
10
G. Huminic, A. Huminic, Application of nanofluids in heat ex-
changers: A review, Renewable and Sustainable Energy Reviews, 16
(2012) 8, 5625–5638, doi:10.1016/j.rser.2012.05.023
T. GANESAN, P. SEENI KANNAN: HEAT-TRANSFER ENHANCEMENT OF NANOFLUIDS IN A CAR RADIATOR
512 Materiali in tehnologije / Materials and technology 52 (2018) 4, 507–512
Figure 11: Experimental comparison of the heat-transfer rate for
various percentages of MNCNT, Al
2
O
3
and water (0.6 m
3
/h)