Experimental evaluation of dynamic viscosity of ZnO–MWCNTs/engine oil hybrid nanolubricant based on changes in temperature and concentration

In this work, an experimental investigation on the effects of temperature and concentration of nanoparticles on the viscosity of ZnO–MWCNTs/engine oil (SAE 10W40) hybrid nanolubricant is presented. The experiments were repeated at volume fractions of 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, and 0.8%, temperature range of 5–55 °C, and shear rates from 666.5 to 13,330 s−1. The viscosity of hybrid nanolubricant was measured using the Brookfield digital viscometer (CAP2000). We found that the nanofluid has a Newtonian behavior at all volume fractions and temperatures. Also, by increasing the volume fraction of nanoparticles and nanotubes at a constant temperature the nanofluid viscosity is increased. Nanofluid viscosity decreases with increasing the temperature at a constant volume fraction.