Sage Journals: Discover world-class research

Abstract

Resistance to fluid flow creates various problems, and fluid viscosity reduction can effectively control these problems. Hydrophilic TiO₂-water and hydrophilic-lipophilic TiO₂-water nanofluids were prepared by stirring and ultrasonic mixing; the rotational viscometer was used to measure the viscosity of nanofluids that formed by different surface modifications of nano-titanium dioxide and deionized water. The results show that the viscosity of TiO₂-water nanofluid increases with the decrease in the temperature and increase in the mass fraction of nanoparticles, the hydrophilic TiO₂-water nanofluids has a slightly larger viscosity than the hydrophilic-lipophilic TiO₂-water nanofluids, and the higher the mass fraction of the nanoparticles is, the greater the difference is.

Keywords

Nano-titanium dioxide nanofluids viscosity hydrophilicity lipophilicity

Introduction

As a physical and chemical property of fluid, viscosity is a physical quantity to measure the fluid viscosity, as well as a presentation of the internal friction caused by the mobilization force from the fluid itself. Fluid with viscosity will generate resistance when it deforms. Nanofluids are typically categorized as suspensions of 1–100 nm particles in fluids. As a new type of heat transferring medium,¹ nanofluids have a higher heat conductivity coefficient than pure water and a lower condensate depression. As a very important physical parameter of nanofluids, the property of viscosity plays a very important role in fluid flowing and heat transfer process. The reduction of viscosity can effectively reduce the resistance of the fluid flow, reducing the energy consumption of the fluid transport, reducing equipment wear and tear.

The viscosity of nanofluids is relative to temperature,^2–14 particle concentration,^{2–11,15–29} particle shape and size,^{2–4,12,13,15,16,30–36} particle density³⁷ and physical properties of the base fluid,^{3,14,17–19,37,38,39} and so on. In addition, the study on the viscosity of nanofluids in model^{3,5–9,20–22,40–46} and shear thinning^{10,11,23,45–49} is relatively comprehensive, but the data on the influence of different hydrophilicity of nanoparticles on the viscosity of nanofluids are still not enough. So, this article adopts nano-titanium dioxide (nano-TiO₂) with different hydrophilicity and deionized water (DIW) to create different nanofluids, and rotational viscometer is used to measure the viscosity, thus to research the influence of hydrophilicity of nanoparticles on the viscosity of nanofluids. The viscosity of the nanofluids can be controlled by modifying the hydrophilicity of nanoparticles, thereby reducing the energy consumption of fluid delivery.

Experiment methods

Experiment materials

The nano-TiO₂ used in the experiment has gone through different surface modifications, which are hydrophilic nano-TiO₂ (Aladdin^®, T104949-500g, Lot# H1603025; average particle size of 10 nm) and hydrophilic-lipophilic nano-TiO₂ (Aladdin^®, T104940-100g, Lot#J1614006; average particle size of 7.5 nm). The hydrophilic type was modified by silica, and the hydrophilic-lipophilic type was modified by silane coupling agent (KH550).

Preparation of nanofluids

Mix certain quality of nano-TiO₂, which should be accurately weighed with an analytical balance with accuracy of 0.1 mg, in a beaker with corresponding amount of DIW, then the mixture was stirred for 2 h. After that, ultrasonically mixed for 1 h, thus to make TiO₂-DIW nanofluids with different mass fractions (0.10, 0.50, 0.99, 1.96, and 3.85 wt%), which are 0.03, 0.13, 0.26, 0.51, and 1.02 vol% in volume fraction. Equation (1) is the conversion formula of mass fraction and volume fraction

$φ = \frac{φ_{m} ρ_{f}}{φ_{m} ρ_{f} + (1 - φ_{m}) ρ_{p}}$ (1)

where φ is the volume percentage of nano-TiO₂ in the nanofluids, φ_m is the weight percentage of nano-TiO₂ in the nanofluids, ρ_f is the density of base fluid, 1.0 g/cm³, and ρ_p is the density of nanoparticles, 3.9 g/cm³.

Viscosity measurement of nanofluids

This experiment uses the NDJ-5S-type rotational viscometer produced by Shanghai Changji Geological Instrument Co., Ltd. The rotor of the viscometer is driven by the motor through the electron speed variation to make constant speed rotation. When the rotor rotates in some kind of liquid, there will be a viscous torque produced to act on the rotor. The more the viscosity is, the greater the viscous torque will be; and the less the viscosity, the weaker the viscous torque. This viscous torque acting on the rotor is detected by sensors, and after computer processing, the viscosity of the liquid can be obtained.

Considering that the viscosity of the liquid to be tested is relatively low, adaptive No. 0 rotor with a low viscosity is adopted, with the speed of the rotor being 60 r/min and the range of the measuring viscometer being 10 mPa s. During the measurement, No. 0 rotor system forms by loading the samples into specially designed water jacket used for measuring low viscosity. Place the whole No. 0 rotor system within glass insulation sleeves, whose temperature is controlled by the circulatory system of DC-2006 low-temperature thermostatic bath produced by Ningbo Xinzhi Biotechnology Co., Ltd, with the temperature control range being 20°C–100°C, and the temperature fluctuations being ±0.05°C. Under these conditions, the viscosity of the nanofluids with different mass fractions of hydrophilic-lipophilic and hydrophilic nano-TiO₂ and DIW was measured at 283.15, 293.15 and 303.15 K, respectively.

The figure of the experimental device is shown as Figure 1.

Figure 1.

Schematic diagram for the viscosity measurement setup.

Experimental result

All viscosity results reported in this article are average values from at least five measurements.

Effect of temperature on the viscosity of TiO₂-DIW nanofluids

Figure 2 shows the effects of temperature on the viscosity of TiO₂-DIW nanofluids. Figure 2(a) is hydrophilic-lipophilic nano-TiO₂, and Figure 2(b) is hydrophilic nano-TiO₂.

Figure 2.

Viscosity of TiO₂-DIW nanofluids as a function of the temperature: (a) hydrophilic-lipophilic nano-TiO₂ and (b) hydrophilic nano-TiO₂. ■ represents the mass fraction of nano-TiO₂-0.00% (wt%), • represents the mass fraction of nano-TiO₂-0.10% (wt%), ▲ represents the mass fraction of nano-TiO₂-0.50% (wt%), ▼ represents the mass fraction of nano-TiO₂-0.99% (wt%), ♦ represents the mass fraction of nano-TiO₂-1.96% (wt%), ◀ represents the mass fraction of nano-TiO₂-3.85% (wt%).

It can be seen from Figure 2 that the viscosity of nanofluids decreases with the increase in the temperature, which is identical to the results from many researchers. Meantime, Figure 2 also shows that with the same concentration, the decreasing speed of the viscosity is getting slower when the temperature gets higher. Take hydrophilic-lipophilic TiO₂-DIW nanofluids as an example, with the mass fraction being 3.85 wt%, when the temperature increases from 283.15 to 293.15 K, the viscosity of the nanofluids will reduce by 25%, and when the temperature increases from 293.15 to 303.15 K, the viscosity of the nanofluids will reduce by 13%.

After fitting the experimental data, it can be found out that the change rules of the viscosity of the nanofluids conform to equation (2) put forward by Namburu et al.⁵⁰ and others, and the correlation coefficient R² of the fitting equation is above 0.9. The fitted value of the parameters A and B in the equation is shown in Table 1

$Log (μ_{nf}) = A e^{- BT}$ (2)

where μ_nf is the viscosity of the nanofluids, mPa S; T is temperature in Kelvin, K; A, B is function of φ, the volume percentage of nanoparticles. Equations (3) and (4) represent the relation expression of the changing rule of parameters A and B of the nanofluids; equation (3) is the nanofluid of DIW and hydrophilic-lipophilic nano-TiO₂, and equation (4) is the nanofluid of DIW and hydrophilic nano-TiO₂

$\begin{matrix} A = 1 \times 10^{7} {(φ)}^{2} - 5 \times 10^{6} (φ) + 208902 \\ R^{2} = 0.9865 \\ B = - 0.308 {(φ)}^{2} - 0.0184 (φ) + 0.1267 \\ R^{2} = 0.9985 \end{matrix}$ (3)

$\begin{matrix} A = 1240 {(φ)}^{2} - 598.59 (φ) + 31.823 \\ R^{2} = 0.9863 \\ B = - 0.0294 {(φ)}^{2} - 0.0717 (φ) + 0.1282 \\ R^{2} = 0.9956 \end{matrix}$ (4)

where φ is the volume percentage of nano-TiO₂ in the nanofluids.

Table 1.

Fitted value of the parameters in equation (2) for the viscosity of nanofluids.

Nanoparticles type andvolume percentage		0.00	0.03	0.13	0.26	0.51	1.02
Hydrophilic-lipophilic nano-TiO₂	A	8.05 × 10¹⁴	6.24 × 10¹⁴	2.57 × 10¹⁴	9.13 × 10¹³	7.75 × 10¹²	5.65 × 10⁸
Hydrophilic-lipophilic nano-TiO₂	B	0.12739	0.12627	0.12286	0.11907	0.11023	0.07566
Hydrophilic nano-TiO₂	A	8.05 × 10¹⁴	2.86 × 10¹⁴	2.27 × 10¹⁴	6.80 × 10¹²	2.77 × 10⁹	719.5462
Hydrophilic nano-TiO₂	B	0.12739	0.12342	0.12215	0.10966	0.08147	0.02536

It can be seen from equations (3) and (4) that the values of A and B are definite values when the concentration of the nanofluids is certain. Under the concentration of the nanofluids in this article, since the maximum value of the volume percentage φ is 0.0102 (1.02%), the maximum value of its squared value φ² is 10⁻⁴. So, the sign symbols of A in equations (3) and (4) depend on the sign symbol of the constant term, which means the values of A in equations (3) and (4) are both above 0. Similarly, the sign symbols of B in equations (3) and (4) also depend on the sign symbol of the constant term, both being above 0.

By deriving equation (2), the derivative μ_nf of the viscosity $μ'_{nf}$ can be obtained (equation (5)). From equation (5), it can be seen that for nanofluids with certain concentration, the values of A and B are constant and with the same sign symbol. The derivative of viscosity to temperature is under zero, and the viscosity decreases with the increase in the temperature

$μ'_{nf} = 10^{A e^{- BT}} \times A e^{- BT} \times \ln 10 \times (- B)$ (5)

It can be seen from Table 1 that the values of A and B of hydrophilic-lipophilic nano-TiO₂ are far bigger than that of the hydrophilic nano-TiO₂, and the difference of these two is getting bigger when the concentration gets larger. So, it can be concluded that the hydrophilicity of nanoparticles in equation (2) has influence on both of parameters A and B.

Effect of mass concentration on the viscosity of TiO₂-DIW nanofluids

Figure 3 shows the effect of nano-TiO₂ mass fraction on viscosity of the TiO₂-DIW nanofluids at 283.15, 293.15, and 303.15 K, respectively.

Figure 3.

Viscosity of TiO₂-DIW nanofluids as a function of the mass fraction of nano-TiO₂ at 283.15, 293.15, 303.15 K, respectively: (a) hydrophilic-lipophilic nano-TiO₂ and (b) hydrophilic nano-TiO₂.

It can be seen from Figure 3 that the viscosity of the nanofluids increased with the increasing mass fraction of nanoparticles, and the increasing speed of the viscosity increased with the increasing mass fraction. With regard to the relationship between viscosity and nanoparticles concentration, Einstein⁵¹ first proposed equation (6). After that, constant amendments were made by Batchelor,⁵² Lundgren,⁵³ Bicerano et al.,⁵⁴ and Pak and Cho⁵⁵ on basis of equation (6), that’s when equations (7)–(10) were obtained. When our experimental data are fitted with these equations, it can be found out that the experiment result conforms to equation (9), and the correlation coefficient R² of the fitting equation is above 0.9. The fitting values of parameters η and k_H are shown in Table 2

$\frac{μ_{nf}}{μ_{f}} = 1 + 2.5 φ$ (6)

$μ_{nf} = μ_{f} (1 + 2.5 φ + 6.5 φ^{2})$ (7)

$μ_{nf} = μ_{f} [1 + 2.5 φ + \frac{25}{4} φ^{2} + f (φ^{3})]$ (8)

$μ_{nf} = μ_{f} (1 + η φ + k_{H} φ^{2})$ (9)

$μ_{nf} = μ_{f} (1 + 39.11 φ + 533.9 φ^{2})$ (10)

where μ_nf is the viscosity of nanofluids, mPa s; μ_f is the viscosity of base fluid, mPa s; η is the Virial coefficient; k_H is the Huggins coefficient; and $φ$ is the volume percentage of nano-TiO₂ in the nanofluids, vol%.

Table 2.

Fitted values of parameters in equation (9) for viscosity of nanofluids.

Temperature (K)		283.15	293.15	303.15
Hydrophilic-lipophilicnano-TiO₂	η	0.24525	0.16047	0.00246
	k_H	0.00893	0.04141	0.19454
	R ²	0.94283	0.98785	0.99296
Hydrophilicnano-TiO₂	η	0.38503	0.21078	0.10491
	k_H	0.87131	1.01885	1.08818
	R ²	0.96437	0.97191	0.97119

The Huggins coefficient is the parameter to characterize the interaction between the polymer and the solvent; Virial coefficient means the internal interaction of the particles. They are related to the shear behavior and used to describe the properties of the particles themselves. Both of Huggins coefficient and Virial coefficient are functions of the temperature.

It can be found from Table 2 that under the same temperature, the values of η and k_H of hydrophilic nano-TiO₂ are both larger than that of hydrophilic-lipophilic nano-TiO₂, so the shear force among the hydrophilic nano-TiO₂ particles and its interaction with the DIW are both larger than that of the hydrophilic-lipophilic nano-TiO₂ particles. Therefore, it can be considered that the relative sliding among hydrophilic-lipophilic nano-TiO₂ particles is relatively weaker than that of the hydrophilic nano-TiO₂ particles. Besides, compared with hydrophilic-lipophilic nano-TiO₂, hydrophilic nano-TiO₂ can more easily agglomerate, and its dispersity in DIW is relatively weaker, which might be greatly related to its larger Virial coefficient. However, the interaction of hydrophilic nano-TiO₂ with DIW is larger than that of the hydrophilic-lipophilic nano-TiO₂, and the water accepting layer on the surface of hydrophilic nano-TiO₂ is thicker than that of the hydrophilic-lipophilic nano-TiO₂.

Effect of the hydrophilicity of the nanoparticles on the viscosity of TiO₂-DIW nanofluids

For comparison, the data in Figure 3 are re-prepared into Figure 4, in which it shows the comparison figure of the viscosity of hydrophilic nano-TiO₂ and hydrophilic-lipophilic nano-TiO₂ under different temperatures.

Figure 4.

Effect of surface modification of nano-TiO₂ on the viscosity: (a) 303.15, (b) 313.15, and (c) 323.15 K.

From Figure 4, it can be seen that under the same temperature, the viscosity of hydrophilic TiO₂-DIW nanofluids is always larger than that of hydrophilic-lipophilic TiO₂-DIW nanofluids, and this trend is increasing with the increase in the mass fraction.

Discussion

Influence of temperature on the viscosity of TiO₂-DIW nanofluids

With the increase in the temperature, the Brownian movement of nanofluids gets stronger; the Brown velocity increases; the average speed of each single molecule increases; the contact time of the particles in the nanofluids decreases; and the time of interaction reduces too; meanwhile, as the Brownian movement intensifies, the distance between molecules increases, resulting in less attraction between molecules. However, the adhesive power between the particles and molecules and the interaction between nanoparticles-molecules and molecules-molecules decrease with the increase in the temperature, that’s why the viscosity of the nanofluids decreases with the increase in the temperature. Besides, under relatively high temperature, the energy of the molecules gets more and the distance among molecules gets larger, resulting in a relatively smaller influence of molecules on each other. Thus, the changing velocity of the viscosity is larger.

Influence of the concentration of the nanofluids on the viscosity of TiO₂-DIW nanofluids

Due to the attraction of van der Waals force existed among the particles of nanofluids, the nanoparticles are inclined to gather to form aggregate in nanofluids, and when the mass fraction of the nanoparticles in the nanofluids increase, the quantity of the nanoparticles will increase too, thus the nanoparticles more easily form bigger aggregate in the nanofluids; meantime, because of the increase in the quantity of the nanoparticles, the average distance between particles is reduced and the interaction between particles increases, which not only increase the shear stress within the nanofluids but also increase the resistance for flowing, thus more power and activation energy are needed to disperse it. So, the viscosity of nanofluids increases with the increase in the concentration of the nanoparticles.

Influence of the hydrophilicity of the nanoparticles on the viscosity of TiO₂-DIW nanofluids

The absorbed water layer can be formed around the nanoparticles in nanofluids, which increases the equivalent radius of nanoparticles. Higher interfacial resistance will form for higher surface area, which will hinder the mobility of the nanoparticles in base fluid, causing the increase in the viscosity. Hydrophilic nano-TiO₂ more easily form absorbed water layer with the surrounding mediums than hydrophilic-lipophilic nano-TiO₂, with the layer being thicker, which results in a higher viscosity of the hydrophilic TiO₂-DIW nanofluids compared with hydrophilic-lipophilic TiO₂-DIW nanofluids.

Conclusion

In summary, we can conclude as follows:

First, the increasing temperature makes the Brownian motion of the nanofluid become more intense, so the viscosity of the nanofluid decreases with increasing temperature.

Second, the van der Waals attractive force of the nanofluid particles increases with the increasing mass fraction of nanoparticles, so the viscosity of nanofluids increases with the increasing mass fraction of nanoparticles.

Finally, the important one and the innovation of this article is the following. The thickness of the absorbed water layer formed around the nanoparticles with different surface hydrophilicity is different. The hydrophilic nanoparticles are easier to form the water-absorbing layer than the hydrophobic nanoparticles, and the water-absorbing layer is thicker. Therefore, the viscosity of nanofluids formed by the hydrophilic nanoparticles is greater than that formed by the hydrophobic nanoparticles.

Footnotes

Handling Editor: Ito Kazuhisa

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research,authorship,and/or publication of this article.

Funding

The author(s) received no financial support for the research,authorship,and/or publication of this article.

References

Choi

SUS

. Enhancing thermal conductive of fluids with nanoparticles. In: Siginer

Wang

(eds) Developments and applications of non-Newtonian flows, FED-vol. 231. New York: ASME, 1995, pp.99–105.

Syzrantsev

Zavyalov

Bardakhanov

. The role of associated liquid layer at nanoparticles and its influence on nanofluids viscosity. Int J Heat Mass Tran 2014; 72: 501–506.

Dalkilic

Küçükyıldırımb

Akdogan Eker

et al . Experimental investigation on the viscosity of water-CNT and antifreeze-CNT nanofluids. Int Commun Heat Mass 2017; 80: 47–59.

Karimi-Nazarabad

Goharshadi

Youssefi

. Particle shape effects on some of the transport properties of tungsten oxide nanofluids. J Mol Liq 2016; 223: 828–835.

Duangthongsuk

Wongwises

. Measurement of temperature-dependent thermal conductivity and viscosity of TiO₂-water nanofluids. Exp Therm Fluid Sci 2009; 33: 706–714.

Sundar

MLS

Hortiguela

Singh

et al . Thermal conductivity and viscosity of water based nanodiamond (ND) nanofluids: an experimental study. Int Commun Heat Mass 2016; 76: 245–255.

Tamizi

Kamalvand

Namazian

. Dependency of the thermophysical properties of nanofluids on the excess adsorption. Int J Heat Mass Tran 2016; 99: 630–637.

Ghodsinezhad

Sharifpur

Meyer

. Experimental investigation on cavity flow natural convection of Al₂O₃-water nanofluids. Int Commun Heat Mass 2016; 76: 316–324.

Sarsam

Amiri

Zubira

MNM

et al . Stability and thermophysical properties of water-based nanofluids containing triethanolamine-treated graphene nanoplatelets with different specific surface areas. Colloid Surface A 2016; 500: 17–31.

10.

Abareshi

Sajjadi

Zebarjad

et al . Fabrication, characterization, and measurement of viscosity of α-Fe₂O₃-glycerol nanofluids. J Mol Liq 2011; 163: 27–32.

11.

Sharifpur

Adio

Meyer

. Experimental investigation and model development for effective viscosity of Al2O3–glycerol nanofluids by using dimensional analysis and GMDH-NN methods. Int Commun Heat Mass 2015; 68: 208–219.

12.

Nguyen

Desgranges

Roy

et al . Temperature and particle-size dependent viscosity data for water-based nanofluids-Hysteresis phenomenon. Int J Heat Fluid Fl 2007; 28: 1492–1506.

13.

Pastoriza-Gallegoa

Casanova

Legido

et al . CuO in water nanofluid: influence of particle size and polydispersity on volumetric behaviour and viscosity. Fluid Phase Equilibr 2011; 300: 188–196.

14.

Lifei

Huangqing

Yang

et al . Nanofluids containing carbon nanotubes treated by mechanochemical reaction. Thermochim Acta 2008; 477: 21–24.

15.

Colangelo

Favale

Miglietta

et al . Thermal conductivity, viscosity and stability of Al2O3-diathermic oil nanofluids for solar energy systems. Energy 2016; 95: 124–136.

16.

Kole

Dey

. Effect of aggregation on the viscosity of copper oxide-gear oil nanofluids. Int J Therm Sci 2011; 50: 1741–1747.

17.

Chen

Witharana

Jina

et al . Predicting thermal conductivity of liquid suspensions of nanoparticles (nanofluids) based on rheology. Particuology 2009; 7: 151–157.

18.

Xinwei

Xianfan

. Thermal conductivity of nanoparticle-fluid mixture. J Thermophys Heat Tr 1999; 13: 474–480.

19.

Sundar

Ramana

Singh

et al . Viscosity of low volume concentrations of magnetic Fe₂O₄ nanoparticles dispersed in ethylene glycol and water mixture. Chem Phys Lett 2012; 554: 236–242.

20.

Kai

Xiaosong

et al . Influence of ingredient s of carbon black nano-particle suspension of ammonia solution on viscosity of nanofluid. J Hunan Univ 2009; 36: 115–118.

21.

Chandrasekar

Suresh

Chandra Bose

. Experimental investigations and theoretical determination of thermal conductivity and viscosity of Al₂O₃/water nanofluid. Exp Therm Fluid Sci 2010; 34: 210–216.

22.

Adio

Mehrabi

Sharifpur

et al . Experimental investigation and model development for effective viscosity of MgO-ethylene glycol nanofluids by using dimensional analysis, FCM-ANFIS and GA-PNN techniques. Int Commun Heat Mass 2016; 72: 71–83.

23.

Phuoc

Massoudi

. Experimental observations of the effects of shear rates and particle concentration on the viscosity of Fe₂O₃-deionized water nanofluids. Int J Therm Sci 2009; 48: 1294–1301.

24.

Banerjee

. Viscosity measurements of multi-walled carbon nanotubes-based high temperature nanofluids. Mater Lett 2014; 122: 212–215.

25.

Bobbo

Fedele

a L

Benetti

a A

et al . Viscosity of water based SWCNH and TiO₂ nanofluids. Exp Therm Fluid Sci 2012; 36: 65–71.

26.

Yang

Zhou

et al . Experimental investigation on the thermal conductivity and shear viscosity of viscoelastic-fluid-based nanofluids. Int J Heat Mass Tran 2012; 55: 3160–3166.

27.

Żyła

Fal

. Viscosity, thermal and electrical conductivity of silicondioxide–ethylene glycol transparent nanofluids: an experimentalstudies. Thermochim Acta 2017; 650: 106–113.

28.

Murshed

SMS

Leong

Yang

. Investigations of thermal conductivity and viscosity of nanofluids. Int J Therm Sci 2008; 47: 560–568.

29.

Mahmoodi

Kandelousi

. Kerosene-alumina nanofluid flow and heat transfer for cooling application. J Cent South Univ 2016; 23: 983–990.

30.

Nguyen

Desgranges

Galanis

et al . Viscosity data for Al₂O₃-water nanofluid-hysteresis: is heat transfer enhancement using nanofluids reliable. Int J Therm Sci 2008; 47: 103–111.

31.

Jeong

Kwon

et al . Particle shape effect on the viscosity and thermal conductivity of ZnO nanofluids. Int J Refrig 2013; 36: 2233–2241.

32.

Prasher

Song

Wang

. Measurements of nanofluid viscosity and its implications for thermal applications. Appl Phys Lett 2006; 89: 133108.

33.

Hojjat

Etemad

Bagheri

et al . Convective heat transfer of non-Newtonian nanofluids through a uniformly heated circular tube. Int J Therm Sci 2011; 50: 525–531.

34.

Yurong

Haisheng

et al . Heat transfer and flow behavior of aqueous suspensions of TiO2 nanoparticles (nanofluids) flowing upward through a vertical pipe. Int J Heat Mass Tran 2007; 50: 2272–2281.

35.

Chevalier

Tillement

Ayela

. Rheological properties of nanofluids flowing through microchannels. Appl Phys Lett 2007; 91: 233103.

36.

Timofeeva

Routbort

Singh

. Particle shape effects on thermophysical properties of alumina nanofluids. J Appl Phys 2009; 106: 014304.

37.

Yousaf

Khan

Imran

et al . Influence of particle size on density, ultrasonic velocity and viscosity of magnetite nanofluids at different temperatures. Nano 2014; 9: 1450089.

38.

Haisheng

Yulong

Yurong

et al . Rheological behaviour of ethylene glycol based titania nanofluids. Chem Phys Lett 2007; 444: 333–337.

39.

Wei

Huaqing

Yang

et al . Experimental investigation on thermal conductivity and viscosity of aluminum nitride nanofluid. Particuology 2011; 9: 187–191.

40.

Phuoc

Massoudi

Chen

. Viscosity and thermal conductivity of nanofluids containing multi-walled carbon nanotubes stabilized by chitosan. Int J Therm Sci 2011; 50: 12–18.

41.

Hosseini

Mohebbi

Ghader

. Correlation of shear viscosity of nanofluids using the local composition theory. Chin J Chem Eng 2010; 18: 102–107.

42.

Chamkha

Abu-Nada

. Mixed convection flow in single- and double-lid driven square cavities filled with water-Al₂O₃ nanofluid: effect of viscosity models. Eur J Mech B: Fluid 2012; 36: 82–96.

43.

Esfe

Razi

Hajmohammad

et al . Optimization, modeling and accurate prediction of thermal conductivity and dynamic viscosity of stabilized ethylene glycol and water mixture Al₂O₃ nanofluids by NSGA-II using ANN. Int Commun Heat Mass 2017; 82: 154–160.

44.

Aminian

. Predicting the effective viscosity of nanofluids for the augmentation of heat transfer in the process industries. J Mol Liq 2017; 229: 300–308.

45.

Halelfadl

Estellé

Aladag

et al . Viscosity of carbon nanotubes water-based nanofluids: influence of concentration and temperature. Int J Therm Sci 2013; 71: 111–117.

46.

Rashin

Hemalatha

. Viscosity studies on novel copper oxide–coconut oil nanofluid. Exp Therm Fluid Sci 2013; 48: 67–72.

47.

Fengchen

Juancheng

Wenwu

et al . Experimental study on the characteristics of thermal conductivity and shear viscosity of viscoelastic-fluid-based nanofluids containing multiwalled carbon nanotubes. Thermochim Acta 2013; 556: 47–53.

48.

Aladag

Halelfadl

Doner

et al . Experimental investigations of the viscosity of nanofluids at low temperatures. Appl Energy 2012; 97: 876–880.

49.

Żyła

Fal

. Experimental studies on viscosity, thermal and electrical conductivityof aluminum nitride–ethylene glycol (AlN–EG) nanofluids. Thermochim Acta 2016; 637: 11–16.

50.

Namburu

Kulkarni

Misra

et al . Viscosity of copper oxide nanoparticles dispersed in ethylene glycol and H₂O mixture. Exp Therm Fluid Sci 2007; 32: 397–402.

51.

Einstein

. Eine neue bestimmung der moleküldimensionen. Annalen Der Physik 1906; 19: 289–306.

52.

Batchelor

. The effect of Brownian motion on the bulk stress in a suspension of spherical particles. J Fluid Mech 1977; 83: 97–117.

53.

Lundgren

. Slow flow through stationary random beds and suspensions of spheres. J Fluid Mech 1972; 51: 273–299.

54.

Bicerano

Douglas

Brune

. Model for the viscosity of particle dispersions. J Macromol Sci: Pol R 1999; 39: 561–642.

55.

Pak

Cho

. Hydrodynamic and heat transfer study of dispersed fluids with submicron metallic oxide particles. Exp Heat Transfer 1998; 11: 151–170.

Effect of different surface modified nanoparticles on viscosity of nanofluids

Abstract

Keywords

Introduction

Experiment methods

Experiment materials

Preparation of nanofluids

Viscosity measurement of nanofluids

Experimental result

Effect of temperature on the viscosity of TiO2-DIW nanofluids

Effect of mass concentration on the viscosity of TiO2-DIW nanofluids

Effect of the hydrophilicity of the nanoparticles on the viscosity of TiO2-DIW nanofluids

Discussion

Influence of temperature on the viscosity of TiO2-DIW nanofluids

Influence of the concentration of the nanofluids on the viscosity of TiO2-DIW nanofluids

Influence of the hydrophilicity of the nanoparticles on the viscosity of TiO2-DIW nanofluids

Conclusion

Footnotes

Declaration of conflicting interests

Funding

References

Effect of temperature on the viscosity of TiO₂-DIW nanofluids

Effect of mass concentration on the viscosity of TiO₂-DIW nanofluids

Effect of the hydrophilicity of the nanoparticles on the viscosity of TiO₂-DIW nanofluids

Influence of temperature on the viscosity of TiO₂-DIW nanofluids

Influence of the concentration of the nanofluids on the viscosity of TiO₂-DIW nanofluids

Influence of the hydrophilicity of the nanoparticles on the viscosity of TiO₂-DIW nanofluids