Abstract: This work is devoted on the rheological behavior of ethylene glycol based nanofluids containing maghemtite nanoparticles. The size of these maghemite nanoparticles was measured using XRD an

G R Bardajee

Z Hooshyar

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Viscosity and  Rheological Behavior of Ethylene 
Glycol-Maghemite Nanofluids
Z. Hooshyar*, G. R. Bardajee 
Department of Chemistry, Payame Noor University, Qazvin Branch, Qazvin, I. R. Iran
(*) Corresponding author: hooshyar@ch.iut.ac.ir
(Received: 22 May 2010 and Accepted: 23 Aug.2010)
 
Abstract:
This work is devoted on the rheological behavior of ethylene glycol based nanofluids containing maghemtite 
nanoparticles. The size of these maghemite nanoparticles was measured using XRD and found to be about <50 
nm. Major factors that influence on viscosity and rheological behavior, such as, temperature and particle mass 
concentration, were investigated over 25–80°C and 0.2 and 2% respectively. It was found that the nanofluids 
show shear-thinning behavior particularly at particle concentrations in excess of 0.2%. Temperature imposes 
a very strong effect on the rheological behavior of the nanofluids at higher temperatures. For a given particle 
concentration, there exists a certain shear rate below which the viscosity decreases by increasing the temperature.
Keywords: Viscosity, Nanofluid, Ethylene glycol, Fe2O3 , Nanoparticle 
1. INTRODUCTION
In traditional heat transfer fluids, properties 
that mainly determine the thermal performance 
of a liquid for heat transfer applications are the 
thermal conductivity, viscosity and density [1]. 
Recently a class of heat transfer fluids containing 
dispersed metallic nanoparticles with typical 
size scales in the order of 1-100 nm has attracted 
great interests. Most attention has been paid in 
the past decade to this new type of heat transfer 
materials due to their enhanced properties and 
behaviors associated with heat transfer, mass 
transfer, wetting, spreading and antibacterial 
activities. These enhanced characteristics implies 
an enormous potential of nanofluids in device 
miniaturization and process intensification which 
could have an impact on many industrial sectors 
including chemical processes, transportation, 
electronics, energy and environment [1,2].
Most published studies on nanofluids deal with 
the heat transfer behavior including thermal 
conductivity [2], phase change (boiling) heat 
transfer [3] and convective heat transfer [4], which 
have been reviewed recently [5]. Very few studies, 
however, have been reported on the rheological 
behavior of nanofluids. Key requirements for 
nanofluids include low solids loading but with high 
thermal properties, favorable rheological properties 
and flow behavior, and great stability over a wide 
range of temperatures to meet the industrial needs. 
Clearly, there is a gap in the literature for studies on 
the rheological behaviors of these fluids. 
Here in, the rheological behavior of a nanofluid 
material is investigated. The focus will be on the 
nanofluids containing spherical particles. We used 
ethylene glycol based Maghemite (EG-Fe2O3) 
nanofluid. The reasons for the use of EG-Fe2O3 
nanofluid can be summarized as: both EG and 
γ-Fe2O3 are generally regarded as a safe material 
for humans and animals although it may change in 
the future with more fundamental research on their 
nano-toxicology and γ-Fe2O3 nanoparticeles can be 
produced on large industrial scales [6-8]. 
Int. J. Nanosci. Nanotechnol., Vol. 6, No. 3,  Sep. 2010, pp. 191-193
Short Communication
192 Hooshyar and Bardajee
2. MATERIALS  AND  METHODS 
2.1. Analytical Methods
In this study, all chemicals are reagent grade and 
deionized distilled water was used to prepare 
nanoparticles. Anhydrous FeCl3 and FeCl2.4H2O were 
obtained from Sigma–Aldrich (USA). Ammonia and 
ethylene glycol were purchased from loba. Chem. 
2.2. Batch Experiment
The nanoparticles (γ-Fe2O3) were prepared 
according to previously reported procedures [9]. 
Briefly, anhydrous FeCl3· (3.25 g) and FeCl2.4H2O 
(1.99 g) were separately dissolved in 20 mL of 
deionized water, followed by the mixing of the 
two iron salt solutions under vigorous stirring (800 
rpm). Then, 30 mL of 25 w/w % aqueous ammonia 
was added to the solution. The color of the bulk 
solution changed from orange to black immediately. 
The magnetic precipitates were washed twice with 
deionized water. The size of the nano particles was 
obtained with an X-ray diffraction. 
The analysis was carried out on the ethylene glycol 
(EG) based nanofluids containing 0.2 and 2 Vol % 
spherical γ-Fe2O3 nanoparticeles at 25-80°C. The 
viscosity of nanofluids (γ-Fe2O3/EG) was measured 
with fungilab F.A. instrument.
3. RESULTS  AND  DISCUSSION
The crystal structure of the synthesized nanoparticles 
was investigated using XRD measurement using 
Cu Kα radiation (Philips, PW1800). It was found 
that the size distribution of the prepared maghemite 
nanoparticles is around 40 nm with a good 
monodispercity (Figure 1).
Figure 2 shows the viscosity of pure EG and EG-
Fe2O3 nanofluids as a function of shear rate at 
25°C. It can be seen that the EG-Fe2O3 nanofluids 
exhibit highly shear-thinning behavior particularly 
when the γ-Fe2O3 concentration exceeds 2%. Such 
behavior is different from the observed Newtonian 
behavior of EG-TiO2 nanofluids containing spherical 
nanoparticles over similar shear rate range [10] 
where the base liquid (EG) is the same as that used 
in the current work. This behavior also is similar 
to the observations of carbon nanotube nanofluids 
[11] and CuO nanorod nanofluids [12], although 
there are important differences between them such 
as temperature dependence.
0
1000
2000
3000
4000
5 20 35 50 65 80
2θ

((200)
(222)
(111) (220)
(311)
Figure 1: XRD patterns of Maghemite 
nanoparticles
Figure 3 shows the measured viscosity at different 
temperatures for 0.2 and 2 Vol. % nanofluids at high 
shear rates. It can be seen that the temperature has 
a very strong effect on the rheological behavior of 
nanofluids. 
The temperature dependence of the entitled 
nanofluids can be interpreted as follows. Given 
the base liquid and nanoparticles, the functional 
dependence of viscosity on shear rate is determined 
by the relative importance of the Brownian diffusion 
and convection effects. The contribution from the 
Brownian diffusion becomes increasingly important 
by increasing the temperature particularly above 
40°C due to the exponential dependence of the base 
liquid viscosity on temperature (Figure 3). At very 
high-shear rates, the Brownian diffusion plays a 
negligible role in comparison with the convective 
contribution and hence independent of the high-
shear viscosity on the temperature.
(200)
q
193
Figure 2: Viscosity as a function of shear rate for 
different nanoparticle concentrations at 25°C. 
(a) 0 Vol. % ; (b) 0.2 Vol. % ; (c) 2 Vol. % 
Figure 3: Viscosity as a function of temperature 
for different nanoparticle concentrations at the 
constant shear rate (a) 0.2 Vol. % ; (b) 2 Vol. %  
International Journal of Nanoscience and Nanotechnology
250
200
150
100
50
0
0 5 10 15 20 25 30 35
4. CONCLUSIONS
It was determined that the viscosity of Ethylene 
glycol solutions increased by increasing Maghemite 
nanoparticle concentrations. Also the viscosity 
of EG-Fe2O3 nanofluids was very sensitive to the 
temperature since its rheological properties were 
significantly affected. This nanofluids show non-
Newtonian behavior under the conditions implied 
in this work. The non-Newtonian shear-thinning 
behavior becomes stronger at lower temperatures or 
higher concentrations. 
REFERENCES
1. Wang, X. Q. & Mujumdar, A. S., Int J Therm 
Sci, 46 (2007): 1–19.
2. Krishnamurthy, S., Lhattacharya, P., Phelan, P. E. 
& Prasher, R. S., Nano Lett 6(3) (2006): 419-423.
3. Wasan, D. T. & Nikolov, A. D., Nature, 423 
(2003): 156-159.
4. Keblinski, P., Eastman, J. A. & Cahill, D. G., 
Mater Today, June Issue (2005): 36-44.
5. Wang, X. W., Xu, X. F. & Choi, SUS, J 
Thermphys Heat Transf, 13(1999): 474.
6. Eastman, J. A., Choi, SUS, Li, S. & Yu, W., 
Thompson, L. J., Appl Phys Lett 78(2001):718-720.
7. He, Y. R., Jin, Y., Chen, H. S., Ding, Y. L. & Cang, 
D. Q., Int J Heat Mass Transf 50 (2007): 2272-2281.
8. L. H. Kligman, F. J. Akin & A. M. Kligman, J. 
Invest. Dermatol. 81 (1983): 98.
9. Van. Ewijk, G. A., Vroege, G. J. & Philipse, 
J. Magnetism and Magnetic Marterials, 
201(1999): 31-33.
10. Chen, H. S., Ding, Y. L. & He, Y. R., Chem Phys 
Lett 444 (4–6) (2007): 333-337.
11. Ding, Y. L., Alias, H., Wen, D. S. & Williams, 
R. A., Int J Heat Mass Transf 49(1–2) (2006): 
240-250.
12. Kwak, K. & Kim, C., Korea-Aust Rheol J 17(2) 
(2005): 35–40.
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150
100
50
0
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Viscosity and Rheological Behavior of Ethylene Glycol-Maghemite Nanofluids

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Viscosity and Rheological Behavior of Ethylene Glycol-Maghemite Nanofluids

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