Turbulent Convective Heat Transfer and Pressure Drop of Graphene-Water Nanofluid Flowing Inside a Horizontal Circular Tube

Turbulent convective heat transfer of graphene-water nanofluids with various concentrations inside a uniformly heated circular tube is studied experimentally. For this purpose, experiments are conducted to measure thermal conductivity, viscosity, pressure drop, and heat transfer coefficient. Results show enhancement of thermal conductivity and moderate increment of viscosity with addition of low amounts of nanoparticles. Moreover, heat transfer coefficient shows relatively high augmentation, and pressure drop remains unchanged. The maximum enhancements are 10.30%, 4.95%, and 6.04% for thermal conductivity, viscosity, and heat transfer coefficient, respectively. UV-Vis spectroscopy results show that the nanofluids are highly stable.