Effect of aggregation on the viscosity of copper oxide–gear oil nanofluids

Kole, Madhusree; Dey, T.K.

doi:10.1016/j.ijthermalsci.2011.03.027

Cited by 266 publications

(95 citation statements)

References 45 publications

(35 reference statements)

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“…At least five types of viscometers with different principles of operations have been used in viscosity measurements, viz. capillary tube viscometer [42,94], vibro-viscometer [17,182], rotating viscometer which includes cone-plate, flat plate and concentric geometries [18,32,43,44,68,76,81,82,85,86,[183][184][185][186][187], falling ball/falling piston viscometer [87] and cup-type viscometer.…”

Section: Experimental Set-upsmentioning

confidence: 99%

“…Moreover, the level of miniaturisation of devices today as technology advances is overwhelming. Devices such as microprocessors, microelectromechanical systems (MEMS), nanoelectromechanical systems (NEMS), microchannels and lab-on-chips come with high-density heat flux that needs quick heat removal for 4 The mismatch between model and experimental results obtained from studies [42][43][44] on the rheological behaviour of nanofluids is of great concern. Besides, [2,45] have shown that despite good agreement between experimental and theoretical results in certain cases, a wide range of constitutive factors need to be incorporated into the models in order to account for the rheological behaviour of the nanofluids in widely varying conditions [39].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Viscosity of Nanofluids: A Review of the Theoretical, Empirical, and Numerical Models

Meyer

Adio

Sharifpur

et al. 2015

Heat Transfer Engineering

201

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The enhanced thermal characteristics of nanofluids have made it one of the fastest-growing research areas in the last decade. Numerous researches have shown the merits of nanofluids in heat transfer equipment. However, one of the problems is the increase in viscosity due to the suspension of nanoparticles. This viscosity increase is not desirable in the industry, especially when it involves flow, such as in heat exchanger or micro-channel applications INTRODUCTIONColloidal suspension dates back to Maxwell's study in 1873 [1]. Though the idea behind his study was vivid, the imposed problems were too enormous for profitable engineering solutions [2]. In 1995, Choi [3] came up with a pioneering idea based on Maxwell's study and suspended ultrafine particles (nanoparticles) in conventional heat transfer fluids. His invention has opened up a myriad of opportunities in research and development. Nanofluids descriptively are colloidal suspensions containing metallic (Ag, Au, Al, Cu, Ni, etc.), non-metallic (single-and multi-wall carbon nanotube (SWCNT and MWCNT), Si, Graphene, etc.), metallic oxide (Al2O3, CuO, NiO2,TiO2, etc.) and oxides of non-metals (SiO2, SiC, MgO, CaCO3, etc.) nanoparticles suspended in conventional heat transfer fluids such as water, engine oil, ethylene glycol, transformer oil, gear oil or mixture of two or more heat transfer fluids [2,3]. When compared with previous microparticle suspensions in conventional heat transfer fluids, it is a special type of fluid with numerous applications potentials because of its enhanced thermal conductivity, stability and homogeneity [3,4]. Microscale particles in suspensions lead to abrasion, clogging of flow paths, pressure drop and high pumping power requirements, therefore, its sustainability was impossible. Besides, nanofluids can reduce the pumping power in engineering equipment significantly and do not pose the problem of clogging and abrasion of equipment flow paths [5][6][7][8]. Therefore, the design and engineering of physical systems are now being tailored towards using nanofluid as working fluid.The impact of colloidal suspension cuts across the fields of science, biological science, medical, pharmaceutical and engineering. In the context of sustainable energy development and thermal management, nanofluids are becoming more and more significant as the need for efficient thermal management is of paramount importance. Moreover, the level of miniaturisation of devices today as technology advances is overwhelming. Devices such as microprocessors, microelectromechanical systems (MEMS), nanoelectromechanical systems (NEMS), microchannels and lab-on-chips come with high-density heat flux that needs quick heat removal for 3 efficient performance, stability and durability, which, from all indications, could be provided by nanofluids for now [9][10][11][12]. The following are also emerging areas of applications of nanoparticles and nanofluids: (i) they could be useful in medicine in the targeted treatment of malignant cells without damaging healthy tis...

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Section: Experimental Set-upsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Viscosity of Nanofluids: A Review of the Theoretical, Empirical, and Numerical Models

Meyer

Adio

Sharifpur

et al. 2015

Heat Transfer Engineering

201

View full text Add to dashboard Cite

show abstract

“…3 Generally, nanofluids have shown higher thermal conductivity 4,5 and specific heat capacity 6,7 as a result of the containing nanoparticles. However, problem of increase in viscosity with regard to the increase in the volume fraction of nanoparticles [8][9][10] is major and requires utmost attention. Besides, a balance must be there between the thermal conductivity and viscosity to be able to maximize the potentials of nanofluids for heat transfer applications.…”

Section: Introductionmentioning

confidence: 99%

Factors affecting the pH and electrical conductivity of MgO–ethylene glycol nanofluids

2015

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Abstract. The pH and electrical conductivity are important properties of nanofluids that have not been widely studied, especially with regard to temperature and ultrasonication energy. To study the factors that affect the pH and electrical conductivity of magnesium oxide-ethylene glycol (MgO-EG) nanofluid, the effects of temperature, volume fraction, particle size and ultrasonication energy were investigated. Two different sizes of MgO were dispersed in EG base fluid up to the volume fraction of 3%, and the pH and electrical conductivity were monitored between the temperatures of 20 and 70°C. Characterization by transmission electron microscopy and size analyses revealed the morphology and sizes of the nanoparticle samples. The pH values dropped consistently with the increase of temperature, while electrical conductivity value increased with the increase of temperature. The experimental result showed that the increase in the MgO volume fraction increased both the pH and electrical conductivity values of the MgO-EG nanofluid. There was no recognizable influence of ultrasonication energy density on the pH and electrical conductivity of the nanofluid; therefore, it was concluded that temperature, volume fraction and particle size are the predominant factors affecting both the pH and electrical conductivity of MgO-EG nanofluid within the present experimental conditions.

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“…The rheological properties of nanofluids are also closely related to the dispersion state of the nanosuspensions, their stability and the presence (or not) of agglomerates. So, it is clear that shear-thinning behaviour of nanofluids is mainly associated with the presence of nanoparticle agglomerates even with Newtonian base fluids [8][9][10][23][24][25].…”

Section: Introductionmentioning

confidence: 99%