Investigation of thermal conductivity and viscosity of ethylene glycol based ZnO nanofluid

Yu, Wei; Xie, Huaqing; Chen, Lifei; Li, Yang

doi:10.1016/j.tca.2009.03.007

Cited by 429 publications

(165 citation statements)

References 27 publications

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“…The shear stress depends linearly on the shear rate and the viscosity is constant, indicating the nanocolloidal dispersions exhibit Newtonian behavior under the conditions used in this study. Newtonian behavior of nanocolloidal dispersions with low volume fraction is consistent with previous research [4,7,8].…”

Section: Resultssupporting

confidence: 92%

“…Newtonian behavior has been observed for very dilute suspensions [4,7] and a considerable amount of effort has been devoted to determining the relationship between the viscosity and volume fraction of suspensions. Yu et al [8] observed shear-thinning behavior when the volume concentration was higher than 0.03. An interesting phenomenon is that most of the viscosities are under-predicted by the traditional Einstein viscosity model [9,10].…”

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confidence: 99%

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Viscosity and aggregation structure of nanocolloidal dispersions

Wang

Luo

et al. 2012

Chin. Sci. Bull.

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In this work, the effects of nanoparticle size, particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated. Both size and pH are found to significantly affect nanocolloid viscosity. Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion. The fractal concept is introduced to describe the irregular and dynamic aggregate structure. The structure of aggregates, which is considered to play an important role in viscosity, is affected by both intermolecular and electrostatic forces. The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction. The aggregate structure is also affected by the pH of the solution. Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force, the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure. In recent years, nanocolloidal dispersions, which are heterogeneous mixtures consisting of very small particles with sizes typically in the order of 1-1000 nm, have attracted much attention for applications related to cooling [1], nanolubricants [2], drug delivery and diagnosis [3]. In the application of nanocolloidal dispersions, the viscosity, which is related to the required pumping power and diffusion properties, plays an important role in delivery systems. The rheological behavior of nanoparticle-fluid mixtures have been investigated experimentally [4][5][6][7]. Newtonian behavior has been observed for very dilute suspensions [4,7] and a considerable amount of effort has been devoted to determining the relationship between the viscosity and volume fraction of suspensions. Yu et al.[8] observed shear-thinning behavior when the volume concentration was higher than 0.03. An interesting phenomenon is that most of the viscosities are under-predicted by the traditional Einstein viscosity model [9,10]. This discrepancy could be caused by aggregation of the nanoparticles and an underestimated effective volume fraction of clusters [10,11]. Rubio-Hernandez et al.[6] also noted that the intrinsic viscosity will be affected by the shape of aggregates, which could be changed by the pH and shear rate of a colloidal system. The formation of aggregates can greatly change the transfer of heat and stress in a system because of their porous structure and large effective volume fraction. Particularly for nanocolloidal dispersions, the distance between aggregates can be in the order of several nanometers. The aggregation of nanoparticles can simply be characterized as ellipsoidal with a certain effective size and axial ratio. The size and shape of aggregates can be determined from dynamic scattering light measurements and intrinsic viscosity data, respectively [6]. Aggregation is a dynamic process and the structure changes continuously because of Brownian m...

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Section: Resultssupporting

confidence: 92%

mentioning

confidence: 99%

Viscosity and aggregation structure of nanocolloidal dispersions

Wang

Luo

et al. 2012

Chin. Sci. Bull.

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“…9 The improvement of the thermal conductivity has been explored for various systems including BN in polyethylene, ZnO in silicone rubber, metal oxides in ethylene vinyl acetate (EVA), modified ZnO in EVA, and ZnO in ethylene glycol. 10,11 Due to the excellent thermal conduction behavior of CNTs, they are also used to enhance the thermal conductivity of polymeric composites not only for improving thermal conductivity but also electric conductivity and mechanical properties. 12,13 CNTs have a unique one-dimensional structure that enables the composites filled with CNTs to have low percolation threshold concentrations.…”

Section: Introductionmentioning

confidence: 99%

Improvement of Thermal Conductivity of Poly(dimethyl siloxane) Composites Filled with Boron Nitride and Carbon Nanotubes

Ha¹,

Hong²,

Kim³

et al. 2013

Polymer Korea

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In order to enhance the thermal conductivity of poly(dimethyl siloxane) (PDMS), boron nitride (BN) and carbon nanotubes (CNTs) were incorporated as the thermally conductive fillers. The amount of BN was increased from 0 to 100 phr (parts per hundred rubber) and the amount of CNTs was increased from 0 to 4 phr at a fixed amount of the boron nitride (100 phr). The thermal conductivity of the composites increased with an increasing concentration of BN, but the incorporation of CNTs had only a slight effect on the enhancement of thermal conductivity. Unexpectedly, the thermal degradation of the composites was accelerated by the addition of CNTs in 100 phr BN filled PDMS. Activation energy for thermal decomposition of the composites was calculated using the Horowitz-Metzger method. The curing behavior, electrical resistivity, and mechanical properties of PDMS filled with BN and CNTs were investigated.

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“…In recent years, much effort has been devoted to effectively improving the dielectric strength and heat transfer properties of mineral oil. Great progress has been made in improving the electrical breakdown strength and heat transfer of mineral oils by using nanoparticles as the modifying agent [2][3][4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

An investigation into the dynamics of partial discharge propagation in mineral oil based nanofluids

Jin

Morshuis

Mor

et al. 2014

2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)

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Abstract-Recent studies present a model which assumes that conductive nanoparticles can reduce the speed of the positive streamer propagation in mineral oil due to electron trapping at the particle surface. Time resolved partial discharge measurements can be used to evaluate the discharge dynamics and to verify this hypothesis. A special measurement setup was built to enable the recording of the discharge dynamics. In this study, the effect of nanoparticles with different conductivities on the discharge dynamics of mineral oil is investigated. The time resolved current shapes of partial discharges in nanofluids and mineral oil are compared. To understand the effect of the conductivity of the nanoparticles on the partial discharge dynamics of mineral oil, nanoparticles with two different conductivities are synthesized with mineral oil. The two types of nanoparticles are silica and fullerene. The host fluid used in this study is Shell DialaS3ZXIG mineral oil.

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Investigation of thermal conductivity and viscosity of ethylene glycol based ZnO nanofluid

Cited by 429 publications

References 27 publications

Viscosity and aggregation structure of nanocolloidal dispersions

Viscosity and aggregation structure of nanocolloidal dispersions

Improvement of Thermal Conductivity of Poly(dimethyl siloxane) Composites Filled with Boron Nitride and Carbon Nanotubes

An investigation into the dynamics of partial discharge propagation in mineral oil based nanofluids

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