Influence of pH and SDBS on the Stability and Thermal Conductivity of Nanofluids

Wang, Xian-ju; Li, Xinfang; Yang, Shuo

doi:10.1021/ef800865a

Cited by 141 publications

(65 citation statements)

References 15 publications

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“…Fedele et al [157] showed that the ultrasonication method of nanoparticles dispersion was more effective than ball milling when they prepared DI-water-based nanofluids of CuO, TiO2 and SWCNHs. The addition of surfactant (dispersant or surface modifier) or pH modification was also shown to be effective [157,180]. However, there have been reports that surfactant and pH sometimes lead to an unnecessary increase in viscosity of nanofluids when not properly modified [82,211].…”

Section: Discussionmentioning

confidence: 99%

“…This is because pH modification has a direct link with the electrostatic condition of the interface between the suspended particles and the fluid medium. In another pH influence investigation, Wang et al [180] systematically prepared optimised Al2O3-water and Cu-water nanofluids by the two-step method using the zeta potential, nanoparticle size and absorbency of the nanofluids as stability indicators. They varied the pH and surfactant concentration (in this case, sodium dodecylbenzene sulfonate (SDS)) to synthesise a stable nanofluid as indicated by the measured values of zeta potential and absorbency.…”

Section: Nanofluid Stabilitymentioning

confidence: 99%

“…Secondly, nanofluid stability is an important issue as already highlighted in this review. The effect of pH on stability cannot be underestimated because through pH modification, nanofluid suspension can be electrostatically stabilised [179,180]. Studies have shown that as the pH of nanofluids moves further away from the IEP, the higher the absolute value of zeta potential, which is the measure of stability.…”

Section: Future Directionmentioning

confidence: 99%

See 2 more Smart Citations

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

Meyer

Adio

Sharifpur

et al. 2015

Heat Transfer Engineering

199

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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: Discussionmentioning

confidence: 99%

Section: Nanofluid Stabilitymentioning

confidence: 99%

Section: Future Directionmentioning

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

199

View full text Add to dashboard Cite

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“…Other similar works have shown that modifying the pH of nanofluid suspension further beyond the IEP have led to the formulation of stable nanofluids. [20][21][22][23] All the above cited literatures are unanimous on the fact that at IEP (point of zero charge on nanoparticles) the nanoparticles will aggregate due to insufficient electrostatic force to overcome the effectiveness of VDW forces of attraction. If the pH changes further away from the IEP, the ionic charge state of the particle surface increases which produces sufficient electrostatic repulsive force that overcomes the VDW forces of attraction.…”

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 stability is due to a large negative zeta potential of Au nanoparticles in water. The influence of pH and sodium dodecylbenzene sulfonate (SDBS) on the stability of two water-based nanofluids was studied [24], and zeta potential analysis was an important technique to evaluate the stability. Zhu et al [25] measured the zeta potential of Al 2 O 3 -H 2 O nanofluids under different pH values and different SDBS concentration.…”

Section: Zeta Potential Analysismentioning

confidence: 99%

Nanofluids

Wang¹,

Xie²,

Che³

2012

Smart Nanoparticles Technology

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Influence of pH and SDBS on the Stability and Thermal Conductivity of Nanofluids

Cited by 141 publications

References 15 publications

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

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

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

Nanofluids

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