Synthesis, characterization and heat transfer study of reduced graphene oxide-Al2O3 nanocomposite based nanofluids: Investigation on thermal conductivity and rheology

Investigation of thermophysical properties of reduced graphene oxide-Al2O3 (rGO-Al2O3) nanocomposite based nanofluid along with convective heat transfer study and associated pressure drop has been done in the present work. Formation of the rGO-Al2O3 nanocomposite was confirmed with the help of various characterization techniques like UV/Vis, XRD, FTIR, Raman spectroscopy, TEM, Elemental mapping and XPS analysis. Thermal conductivity at different temperatures of various volume % (0.01-0.1%) of the prepared rGO-Al2O3 nanofluid was measured by dispersing and ultrasonicating the nanocomposite in deionized water. Thermal conductivity increased with increase in temperature as well as concentration of the rGO-Al2O3 nanofluid. These nanofluids exhibited non-Newtonian behavior as found from their rheological study. Different viscosity models also were employed to predict the viscosity at a range of applied shear rate (0-2000 s(-1)). Convective heat transfer study at a wall condition of constant heat flux was done at different concentration and Reynolds number of the rGO-Al2O3 nanofluid. Maximum value of heat transfer coefficient of 5461.602 W/m(2)degrees C was achieved at the exit of test section by using 0.05 vol.% rGO-Al2O3 nanofluid flowing at Reynolds number of 7510.

Automated summary

In this study, the formation of rGO-Al2O3 nanocomposite was confirmed using various characterization techniques, and the thermal conductivity of the nanofluid was found to increase with temperature and concentration. The nanofluids exhibited non-Newtonian behavior, and showed promising results for convective heat transfer studies.