Experimental investigation on the viscosity characteristics of water based SiO2-graphite hybrid nanofluids

The hybrid nanofluids were obtained by dispersing Silicon dioxide and Graphite nanoparticles in distilled water. Viscosity is regarded as internal resistant of a fluid, and it affects the pumping power and the convective heat transfer coefficient. This hybridization requires to be experimentally determined since its properties are unknown. For viable real life applications viscosity and density parameters are significant, owing to their influence on energy and cost saving of heat exchangers by affecting pressure drops. The viscosity measurements of hybrid nanofluids were performed using capillary tube viscometer, within a temperature range of 15 °C to 60 °C at several volume concentrations up to 2%. Furthermore, the volumetric fraction ratios within nano composites have also been changed, since there is more than one nano particle. The highest increment of viscosity was observed to be 36.12% in the nanofluid of 2 vol% at 15 °C. The conclusion was supported with SEM images and a regression correlation was proposed and afterward the results were compared with relevant literature. It is able to estimate the viscosity of hybrid nanofluid with 2.4% accuracy.