Viscosity and Rheological Properties of Graphene Nanopowders Nanofluids

Abstract

The dynamic viscosity and rheological properties of two different non-aqueous graphene nano-plates-based nanofluids are experimentally investigated in this paper, focusing on the effects of solid volume fraction and shear rate. For each nanofluid, four solid volume fractions have been considered ranging from 0.1% to 1%. The rheological characterization of the suspensions was performed at 20 ∘C, with shear rates ranging from 10−1s−1 to 103s−1, using a cone-plate rheometer. The Carreau–Yasuda model has been successfully applied to fit most of the rheological measurements. Although it is very common to observe an increase of the viscosity with the solid volume fraction, we still found here that the addition of nanoparticles produces lubrication effects in some cases. Such a result could be very helpful in the domain of heat extraction applications. The dependence of dynamic viscosity with graphene volume fraction was analyzed using the model of Vallejo et al.

Viscosity of graphene in lubricating oil, ethylene glycol and glycerol

“…After fitting the data of viscosity with volume fractions using the model (5), for different shear rates. In the case of EG, the model applied well to the description of the evolution of EG viscosity as a function of GNP volume fraction φ and a quasi-systematic increase in the dynamic viscosity with the GNP volume fraction has been observed, whatever the shear rate considered, which is same observed in the study of Bakak et al [3]. For GL, the results of fitting the Vallejo model are in good agreement with the data.…”

“…In Fig. 7, it can be observed that the viscosity of EG+GNP8 nanofluids also decreases at higher temperatures and similar trends have also been observed before [3,5]. There is an evident increase of viscosity at high concentrations, e.g.…”

“…Within the shear rates range investigated, 1 ≤ γ ≤ 1000, it is observed that the shear viscosity is dependent on the shear rate and the solid fraction. In comparison with previous experiments [3] using a cone-plate geometry, the present viscosity increase at low shear rate is smaller. Presumably, the concentric cylinder geometry limits slip at the wall but enhances the sedimentation effect that maybe present for LO.…”

“…Presumably, the concentric cylinder geometry limits slip at the wall but enhances the sedimentation effect that maybe present for LO. Bakak et al [3] used the Carreau-Yasuda (CY) model to fit their rheological measurements results: where η 0 is he zero-shear rate dynamic viscosity, η ∞ is the infinite shear rate dynamic viscosity and, λ is a relaxation time characteristic of the studied fluid, a is a parameter characteristic of the transition width between the zero-shear rate viscosity domain and the shear-thinning domain and n is the power law index. Unfortunately, the present measurement do not give access to µ 0 as the zero shear rate plateau is not clearly observed.…”

Therapeutic potential of nanotechnology-based approaches in osteoarthritis

“…Therefore, finding a more effective lubricant for OA patients may be of great significance for the improvement of their joint function ( Lin and Klein, 2021 ). The lubricant suspension added with NPs is called nano-lubricant, and NPs can be stably suspended in the lubricant to enhance the lubrication effect of the lubricant ( Bakak et al, 2021 ). Graphite nanoplatelets (GNP) can improve the lubricating property of the lubricant.…”