Abstract
The in situ growth and chemical co-precipitation method was used for the synthesis of uniform dispersion of Co3O4 nanoparticles on the graphene oxide (GO) nanosheet. The reductions of aqueous cobalt chloride in the presence of GO with sodium borohydrate result in the formation of hybrid GO/Co3O4 nanoparticles. The synthesized GO/Co3O4 nanoparticles were characterized using X-ray power diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The hybrid nanofluids were prepared by dispersing synthesized GO/Co3O4 nanoparticles in water, ethylene glycol, and ethylene glycol/water mixtures. The properties such as thermal conductivity and viscosity were estimated experimentally at different volume concentrations and temperatures. The thermal conductivity enhancement of water based nanofluid is 19.14% and ethylene glycol based nanofluid is 11.85% at 0.2% volume concentration and at a temperature of 60 degrees C respectively compared to their respective base fluids. Similarly, the viscosity enhancement of water based nanofluid is 1.70-times and ethylene glycol based nanofluid is 1.42-times at 0.2% volume concentration and at a temperature of 60 degrees C respectively. The obtained thermal conductivity and viscosity data is compared with the literature values. (C) 2017 Elsevier Ltd. All rights reserved.