Effect of Shear Rate, Temperature, and Particle Concentration on the Rheological Properties of ZnO and ZrO₂Nanofluids

Abstract

The rheological behavior of ZnO and ZrO 2 nanoparticle suspensions in a polyalphaolefin (PAO 6) was investigated at high shear rates. Nanoparticles were dispersed at 0.5, 1.0, and 2.0 wt% in PAO 6 using an ultrasonic probe to produce nanofluids whose viscosity was determined over shear rates and temperatures ranging from 10 6 to 10 7 s −1 and 40 to 100 • C, respectively. For the particle concentrations tested, the nanofluids exhibited a shear-thinning rheological behavior. The classical models typically used to predict nanofluid viscosity failed under these conditions because the viscosity depends not only on the temperature but also on the shear rate imposed. Two new experimental viscosity models were developed and validated for the studied nanofluids and constitute a practical tool to estimate the tribological behavior in lubricated pairs.

Viscosity, density, and thermal conductivity of aluminum oxide and zinc oxide nanolubricants

“…For example, the nanolubricants of Hernandez Battez et al (2014) were Newtonian for shear rates less than 700 s −1 and non-Newtonian for significantly larger shear rates (10 6 s −1 to 10 7 s −1 ). Conversely, all of Tseng and Lin (2003) water-based nanofluids exhibited non-Newtonian behavior for shear rates less than 700 s −1 and one of them showed Newtonian behavior for shear rates larger than 700 s −1 .…”

Effects of hexagonal boron nitride based nanofluid on the tribological and performance, emission characteristics of a diesel engine: An experimental study

“…Nanoparticles are responsible for increasing the thermal conductivity of base fluid because of its size which is generally in the extent of 1 to 100 nm 13 . The nanoparticles dispersion in the base oil is termed as Nanofluid 14 . Most of the literature was focused on the use of oxide‐based nanoparticles such as aluminium oxide (Al 2 O 3 ), copper oxide (CuO), and titanium oxide (TiO 2 ) due to their increasing combustion efficiency characteristics.…”

Tribological Properties of the Lubricant Containing Titanium Dioxide Nanoparticles as an Additive

“…Thus, it can be concluded that both methods (listed above) are classical and have their own defects (the addition of dispersant or usage of surfactant into base oil) for solving the oil solubility of TiO 2 nanoparticles. This claim is strengthened by the works of several researchers [3,[8][9][10][11]23,24,[36][37][38]. Therefore, the application process of the two classical methods was named the traditional process (TP).…”

“…The use of nanoparticles as oil additives and lubricants is a recent idea. Numerous nanoparticles have been investigated in recent years [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. These oil additives contain small particles of solid material, and their use is not straightforward and only recently has been recognized as feasible.…”