Sedimentation and stabilization of nano-fluids with dispersant

Abdullah, Muhammad; Malik, Shahid Raza; Iqbal, Muhammad Haseeb; Sajid, Muhammad Munir; Shad, Naveed Akhtar; Hussain, Syed Zajif; Razzaq, Wasif; Javed, Yasir

doi:10.1016/j.colsurfa.2018.06.030

Cited by 40 publications

(12 citation statements)

References 23 publications

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“…In all cases, a tendency of the nanocellulose particles to agglomerate along with the subsequent settling was observed. This is a practical drawback of these nanofluids, which may prevent their reliable and useful characterization . In consequence, all samples were sonicated for 5 min just before measuring them, in such a way that agglomeration of nanoparticles was mitigated, and only homogeneous dispersions were passed on for subsequent dielectric, electrorheological, and electrotribological characterization.…”

Section: Methodsmentioning

confidence: 99%

On the Electro-Active Control of Nanocellulose-Based Functional Biolubricants

Canto

Fernández-Silva

Roman

et al. 2020

ACS Appl. Mater. Interfaces

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This research work aims to explore the development of functional nanocellulose-based biolubricants, which allow for an electro-active control of the friction behavior. With this purpose, the influence of both nanocellulose concentration and electric field strength on the lubricant's electrorheological behavior was analyzed. Electric field strengths up to 4 kV/mm were imposed and two different kinds of nanocellulose were studied as the polarizable particulate phase: cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs). Nanocellulose particles were added to castor oil at weight fractions ranging from 0 to 6 wt %. All dispersions exhibited a noticeable variation in their dielectric constant, but not in their conductivity, within a wide frequency range between 1 Hz and 200 kHz, and their dielectric behavior was significantly affected by the particle weight fraction. Noteworthily, it was found that the critical value of nanocellulose concentration, 4 wt %, at which the electro-viscous effect displayed by these dispersions was constrained, yielding a limiting electrorheological (ER) behavior. In addition, the dynamic yield stress dependence on the electric field strength showed a critical value within the interval of 0.8−1.2 kV/mm, suggesting a nonlinear conduction model for these nanocellulose-based ER dispersions. Finally, a maximum leak current intensity for 1 wt % CNF or CNC dispersions and an asymptotic decay at higher concentrations were observed. We conclude that both CNC and CNF nanoparticles have demonstrated that they can endow castor oil with significant ER properties, which remarkably reduced the friction coefficient within the boundary and mixed lubrication regions at electric field strengths lower than 40 V.

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Section: Methodsmentioning

confidence: 99%

On the Electro-Active Control of Nanocellulose-Based Functional Biolubricants

Canto

Fernández-Silva

Roman

et al. 2020

ACS Appl. Mater. Interfaces

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“…The stability of nanofluids is one of the major factors determining effectiveness, so the sedimentation and stabilization of alumina nanoparticles (size ~50 nm) in an ethanol-water mixture with and without dispersant was investigated experimentally by Abdullah et al [ 133 ]. The sodium salt of polymethacrylic acid was used to measure the stability.…”

Section: Thermophysical Properties Of Nanofluids: Fundamentals and Ch...mentioning

confidence: 99%

Application of Nanofluids in Gas Turbine and Intercoolers—A Comprehensive Review

et al. 2022

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Today, the optimal use of non-renewable energy sources, reducing pollution, and increasing the efficiency of power-generating cycles are of particular importance. There are several ways to increase the efficiency of gas turbines; one that has recently attracted attention is to use an intercooler. However, the efficiency of the heat exchanger used in intercoolers depends on the type of heat exchanger, the characteristics of the operating fluid and the thermal boundary layers, and the pump speed. Improving the thermophysical properties of the working fluid is a passive method of increasing heat transfer, which has attracted the attention of those researching engineering applications. The current review addresses the latest methods of improving gas turbine efficiency using nanofluids and includes experimental and numerical studies. First, the general principles governing turbines are described, then the commonly used types of heat exchangers are introduced. Finally, studies on the use of nanofluids in heat exchangers are reviewed. The technology of producing nanoparticles that can be used in heat exchangers is also discussed. This review article can provide the reader with comprehensive information on making nanofluids and using them in heat exchangers used as intercoolers.

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“…The reaction products are linked together in the form of ionic bonds, thus forming a single molecule coating on the surface of nanoparticles, forming a microcellular shape, which can effectively avoid the contact of nanoparticles and forms a steric hindrance to prevent a large number of particles from settling. If the amount of the surfactant is too small to completely cover the surface of all particles, causing some particles to agglomerate and settle, But if the amount of the surfactant is too large, the modi er is simultaneously adsorbed on two or more adjacent Particle surfaces, bridging between particle surfaces are more likely to form larger aggregates to accelerate sedimentation and reduce the stability of the nano uid, so matching an appropriate amount of surfactant with the nanoparticles is of great signi cance [41,44,59].…”

Section: Effect Of Surfactant Concentrationmentioning

confidence: 99%

Effect of Mixing Temperature, Ultrasonication Duration and Nanoparticles/Surfactant Concentration on the Dispersion Performance of Al2O3 Nanolubricants

Liu¹,

Hou²,

Li³

et al. 2020

Preprint

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The main goal of this study is to improve the dispersion stability of Al2O3 nanoparticles in polyalphaolefin oil to overcome the sedimentation problem of nanoparticles using the addition of oleic acid as a surfactant. This work investigates the effect of the settling time, temperature, ultrasonic duration and nanoparticles/surfactant (oleic acid) concentration on the dispersion stability of Al2O3 nanoparticles in oil-based solutions. Herein, the visual observation, UV–Vis spectroscopy, dynamic light scattering (DLS) analysis, and transmission electron microscopy (TEM) images were used to evaluate the dispersion stability of the Al2O3 nanoparticles. The results reveal that the thermal method during the synthesis of nanofluids using 50 °C temperature improves the dispersion of nanoparticles. The results also exhibited that increasing the ultrasonic amplitude and prolonging the ultrasonic time during the synthesis of nanofluids influences the dispersion stability. The results showed that the nanolubricant with 0.8 wt.% oleic acid provides better dispersion behavior. Furthermore, the nanolubricants containing 0.005wt% and 0.01wt% Al2O3 nanoparticles demonstrated outstanding dispersion performance, and the stability time reached more than 160 days.

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Sedimentation and stabilization of nano-fluids with dispersant

Cited by 40 publications

References 23 publications

On the Electro-Active Control of Nanocellulose-Based Functional Biolubricants

On the Electro-Active Control of Nanocellulose-Based Functional Biolubricants

Application of Nanofluids in Gas Turbine and Intercoolers—A Comprehensive Review

Effect of Mixing Temperature, Ultrasonication Duration and Nanoparticles/Surfactant Concentration on the Dispersion Performance of Al2O3 Nanolubricants

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