An experimental study on the rheological behavior of hybrid Tungsten oxide (WO3)-MWCNTs/engine oil Newtonian nanofluids.

In recent years, numerous studies have been done on the rheological behavior and heat transfer of nanofluids. In this paper, an experimental study on the rheological behavior of hybrid WO 3 -MWCNTs/Engine Oil hybrid Newtonian nanofluid has been carried out. Tungsten oxide (WO 3) nanoparticles have diameter of 23–65 nm and MWCNTs nanoparticles have diameter of 20–30 nm. Experiments were carried out at 6 vol fraction of nanoparticles of φ = 0, 0.05, 0.1, 0.2, 0.4 and 0.6% at the temperatures of 20, 30, 40, 50 and 60 °C. The results show that the relationship between the shear rate and shear stress of the base fluid and the hybrid nanofluid of WO 3 -MWCNTs/Engine Oil is linear at all temperatures and volume fraction of nanoparticles. So, the base fluid and the hybrid nanofluids are Newtonian. Also, with increasing temperature, the viscosity of nanofluid decreases and with increasing volume fraction of nanoparticles, the viscosity increases. Finally, a mathematical model has been proposed to estimate the nanofluid viscosity. The results obtained from the model show good compatibility with experimental values. Image 10478 • Experimental investigation for developing a new model for rheological behavior of nanofluid. • Tungsten oxide-MWCNTs/motor Oil hybrid Newtonian nanofluid was prepared. • Experiments were repeated at different shear rates. • The viscosity at different solid volume fractions was measured. [ABSTRACT FROM AUTHOR]