Rheological behaviour of functionalized graphene nanoplatelet nanofluids based on water and propylene glycol:water mixtures

Vallejo, Javier P.; Żyła, Gaweł; Fernández-Seara, José; Lugo, Luis

doi:10.1016/j.icheatmasstransfer.2018.10.001

Cited by 45 publications

(47 citation statements)

References 70 publications

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“…The dynamic viscosity values in the second plateau for the fGnP nafluid set were modelled by means of Vallejo et al’s equation [33], which includes, in the same expression, the concentration and temperature dependences of viscosity: η=η0·eA·T0T−T0+B·eCT· ϕv −D·ϕv2 with B , C , and D as the fitting parameters; η 0 , A , and T 0 as the previously fitted parameters from the VFT equation, Equation (3), for the corresponding base fluid; and ϕ v as the volume fraction. This equation was tested in previous works [33,34,66] for experimental viscosities of GnP-water dispersions [34,39], GnP-propylene glycol water 10:90 wt% dispersions [33], GnP-propylene glycol water 30:70 wt% dispersions [33,34,66], and GnP-propylene glycol water 50:50 wt% dispersions [34], obtaining very good results. Table 5 and Figure 7 show the goodness of Equation (4) for the fGnP nanofluids of this study, the reached AAD being lower than 0.9%.…”

Section: Resultsmentioning

confidence: 99%

Influence of Six Carbon-Based Nanomaterials on the Rheological Properties of Nanofluids

et al. 2019

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Nanofluids, dispersions of nanosized solid particles in liquids, have been conceived as thermally-improved heat transfer fluids from their conception. More recently, they have also been considered as alternative working fluids to improve the performance of direct absorption solar thermal collectors, even at low nanoadditive concentrations. Carbon-based nanomaterials have been breaking ground in both applications as nanoadditives during the last decade due to their high thermal conductivities and the huge transformation of optical properties that their addition involves. In any application field, rheological behavior became a central concern because of its implications in the pumping power consumption. In this work, the rheological behavior of four different loaded dispersions (0.25, 0.50, 1.0, and 2.0 wt%) of six carbon-based nanomaterials (carbon black, two different phase content nanodiamonds, two different purity graphite/diamond mixtures, and sulfonic acid-functionalized graphene nanoplatelets) in ethylene glycol:water mixture 50:50 vol% have been analysed. For this purpose, a rotational rheometer with double cone geometry was employed, which included a special cover to avoid mass losses due to evaporation at elevated temperatures. The flow curves of the twenty-four nanofluids and the base fluid were obtained by varying the shear rate between 1 and 1000 s−1 for seven different temperatures in the range from 283.15 to 353.15 K. The shear-thinning behaviors identified, as well as their dependences on carbon-based nanomaterial, concentration, and temperature, were analyzed. In addition, oscillatory tests were performed for samples with the clearest Non-Newtonian response, varying the deformation from 0.1 to 1000% with constant frequency and temperature. The dependence of the behaviors identified on the employed carbon-based nanomaterial was described.

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Section: Resultsmentioning

confidence: 99%

Influence of Six Carbon-Based Nanomaterials on the Rheological Properties of Nanofluids

et al. 2019

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“…But this should not be their only application; viscosity also plays a vital role in the efficiency of nanofluids in the convection processes. Vallejo et al [11] studied the rheological behavior of a graphene nanofluid by means of a rotational rheometer. They found that the nanofluid behaved as a non-Newtonian shear thinning liquid at a specific temperature and with a specific ratio of water and propylene glycol.…”

Section: Introductionmentioning

confidence: 99%

Symmetric MHD Channel Flow of Nonlocal Fractional Model of BTF Containing Hybrid Nanoparticles

et al. 2020

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A nonlocal fractional model of Brinkman type fluid (BTF) containing a hybrid nanostructure was examined. The magnetohydrodynamic (MHD) flow of the hybrid nanofluid was studied using the fractional calculus approach. Hybridized silver (Ag) and Titanium dioxide (TiO2) nanoparticles were dissolved in base fluid water (H2O) to form a hybrid nanofluid. The MHD free convection flow of the nanofluid (Ag-TiO2-H2O) was considered in a microchannel (flow with a bounded domain). The BTF model was generalized using a nonlocal Caputo-Fabrizio fractional operator (CFFO) without a singular kernel of order α with effective thermophysical properties. The governing equations of the model were subjected to physical initial and boundary conditions. The exact solutions for the nonlocal fractional model without a singular kernel were developed via the fractional Laplace transform technique. The fractional solutions were reduced to local solutions by limiting α → 1 . To understand the rheological behavior of the fluid, the obtained solutions were numerically computed and plotted on various graphs. Finally, the influence of pertinent parameters was physically studied. It was found that the solutions were general, reliable, realistic and fixable. For the fractional parameter, the velocity and temperature profiles showed a decreasing trend for a constant time. By setting the values of the fractional parameter, excellent agreement between the theoretical and experimental results could be attained.

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“…An increase in viscosity as the nanoparticle concentrations rise has been frequently observed in graphene-based [23,26,56,57,58,59] and other NFs [23,26]. This enhancement has been commonly associated with the tendency of the nanoparticles to agglomerate under pressure.…”

Section: Resultsmentioning

confidence: 98%

“…This enhancement has been commonly associated with the tendency of the nanoparticles to agglomerate under pressure. The agglomerates raise the internal shear stress and the resistance to flow in the NF, which leads to an increase in viscosity during measurement [58].…”

Section: Resultsmentioning

confidence: 99%

Modification of the Raman Spectra in Graphene-Based Nanofluids and Its Correlation with Thermal Properties

et al. 2019

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It is well known that by dispersing nanoparticles in a fluid, the thermal conductivity of the resulting nanofluid tends to increase with the concentration of nanoparticles. However, it is not clear what the mechanism behind this phenomenon is. Raman spectroscopy is a characterization technique connecting the molecular and macroscopic world, and therefore, it can unravel the puzzling effect exerted by the nanomaterial on the fluid. In this work, we report on a comparative study on the thermal conductivity, vibrational spectra and viscosity of graphene nanofluids based on three different amides: N, N-dimethylacetamide (DMAc); N, N-dimethylformamide (DMF); and N-methyl-2-pyrrolidinone (NMP). A set of concentrations of highly stable surfactant-free graphene nanofluids developed in-house was prepared and characterized. A correlation between the modification of the vibrational spectra of the fluids and an increase in their thermal conductivity in the presence of graphene was confirmed. Furthermore, an explanation of the non-modification of the thermal conductivity in graphene-NMP nanofluids is given based on its structure and a peculiar arrangement of the fluid.

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Rheological behaviour of functionalized graphene nanoplatelet nanofluids based on water and propylene glycol:water mixtures

Cited by 45 publications

References 70 publications

Influence of Six Carbon-Based Nanomaterials on the Rheological Properties of Nanofluids

Influence of Six Carbon-Based Nanomaterials on the Rheological Properties of Nanofluids

Symmetric MHD Channel Flow of Nonlocal Fractional Model of BTF Containing Hybrid Nanoparticles

Modification of the Raman Spectra in Graphene-Based Nanofluids and Its Correlation with Thermal Properties

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