Enhanced thermal conductivities of graphene oxide nanofluids.

In this study, graphene oxide (GO) nanosheets were synthesized by the modified Hummers method. GO structure was estimated by XRD, UV–vis-spectrophotometer and SEM imaging. Then homogeneous and stable GO/water nanofluid was prepared. The effects of GO concentration and temperature on the thermal conductivity were investigated. The measurements of thermal conductivity indicate that the nanofluids have substantially higher thermal conductivities than the base fluid. The thermal conductivity enhancement depends strongly on the concentration of GO and increases with the increasing loading. When the nanosheet loading is 0.25 wt.%, the enhancement ratio is 33.9% at 20 °C and when the temperature increased to 40 °C the enhancement is up to 47.5%. Therefore the level of enhancement is dependent of temperature in the measured temperature range. [ABSTRACT FROM AUTHOR]