Performance and Characterization Studies of Reduced Graphene Oxides Aqua Nanofluids for a Pool Boiling Surface

This experimental study deals with the critical heat flux (CHF) of aqua-based reduced graphene oxide (rGO) nanofluids at 0.2 %, 0.6 %, and 0.8 % concentrations. This investigation also interprets the results of different characterization studies of rGO nanofluid namely atomic force microscopy (AFM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), zeta potential and Branauer-Emmett-Teller (BET) surface area analysis to confirm the existence. Thermal conductivity and dynamic viscosity of the working fluid are measured over a range of temperatures (30-70 degrees C). From this investigation, it is inferred that the thermal conductivity increases with the increase in temperature while its viscosity gets reduced for both deionized water and rGO nanofluid. The heat transfer coefficient (HTC) augmentation is observed to be 0.9, 1.8, and 2.3 times greater than deionized water corresponding to 0.2 %, 0.6 %, and 0.8 % concentrations of rGO nanofluids. The HTC of the synthesized nanofluid increases with increase in concentration of rGO and its compared than deionized water. The CHF enhancement or deterioration by rGO nanofluids is due to the different volume concentrations including heat transfer surface and their interaction and the nanoparticles suspended in the liquid.