INFLUENCE OF THERMOPHYSICAL CHARACTERISTICS ON FIGURE-OF-MERIT IN TURBULENT HEAT TRANSFER OF WATER AND ETHYLENE GLYCOL MIXTURE BASED RGO/NANODIAMOND HYBRID NANOFLUIDS

Abstract

The advantages of hybrid nanofluids over single-phase heat transfer fluids are greater. The thermophysical properties of hybrid nanofluids are critical before examining their heat transfer coefficient in a thermal device. For the manufacture of stable rGO/nanodiamond hybrid nanofluids, different base fluids such as 80:20%, 60:40%, and 40:60% (weight percentage) of water and ethylene mixture was used. At particle concentrations ranging from 0.2 to 1.0% and temperatures ranging from 20° C to 60° C, the thermophysical characteristics were examined experimentally. Under the turbulent flow condition, the figures-of-merit were analyzed from the thermophysical characteristics and various models. For the heat transfer coefficient and pumping power analysis, the same fluid velocity and diameter parameters for hybrid nanofluids and the base fluid were used. The thermal conductivity increase of 80:20% water and ethylene glycol (W/EG) nanofluid is 25.47; of 60:40% W/EG nanofluid is 20.47%; and of 40:60% W/EG nanofluid is 18.57% at 60° C, as compared to their own base fluids. Furthermore, compared to base fluid data, the viscosity increase of 1.0% vol. of nanofluid at 20° C for 80:20% W/EG nanofluid is 76.77%; 60:40% W/EG nanofluid is 81.63%; and 40:60% W/EG nanofluid is 88.70%. The obtained figures of merit for all cases of the hybrid nanofluid are less than unity.