The rheological behavior of MWCNTs–ZnO/Water–Ethylene glycol hybrid non-Newtonian nanofluid by using of an experimental investigation

In the current study, an experimental study was carried out on the rheological properties of hybrid non-Newtonian nanofluid (MWCNTs–ZnO/Water–Ethylene glycol (80:20 vol.%)) to develop a new model. The viscosities of nanofluid were evaluated in the temperature range of 25–50 °C with volume fractions of φ = 0.075%, 0.15%, 0.3%, 0.6%, 0.9%, and 1.2%. We find that the effect of changes is more obvious when the φ is increased. So the property of non-Newtonian nanofluid is more likely to appear. In addition to a temperature of 25 °C, the viscosity increase from a φ = 0% to 1.2% is higher than 90%, which is very significant. Also, in the maximum φ, at T = 50 °C, 40 °C and 30 °C, the viscosity reduction is 21%, 17%, and 8%, respectively, relative to the reference temperature (25 °C). The above results can be of great help to engineers in designing thermal systems to increase heat transfer and considering pumping power.