Effects of temperature and solid volume fraction on viscosity of SiO2-MWCNTs/SAE40 hybrid nanofluid as a coolant and lubricant in heat engines

In this study, an experimental investigation on the effects of temperature and concentration of nanoparticles on the dynamic viscosity of SiO2-MWCNTs/engine oil (SAE40) hybrid nanofluid is presented. The experiments were performed in the solid volume fraction range of 0-1.0% and temperature ranging from 25 °C to 60 °C. Viscosity measurements showed that SiO2-MWCNTs/SAE40 hybrid nanofluid behaves as a Newtonian fluid at all considered solid volume fractions and temperatures. Experimental results also revealed that the dynamic viscosity enhances with an increase in the solid volume fraction and decreases with increasing temperature. Moreover, results indicated that the maximum enhancement of viscosity of the hybrid nanofluid was 37.4%. Finally, an accurate correlation with maximum deviation of 0.75% has been proposed to predict the dynamic viscosity of SiO2-MWCNTs/SAE40 hybrid nanofluids.