Heat transfer, entropy generation, economic and environmental analyses of linear fresnel reflector using novel rGO-Co3O4 hybrid nanofluids

This work aims to enhance the heat transfer of a small prototype linear Fresnel reflector by using rGOCo(3)O(4)/water hybrid nanofluids at a location in Blida region, in Algeria. Hybrid nanofluids, with varying concentrations (0.05, 0.10, and 0.20 wt%) and temperatures (20-60 degrees C), are prepared. For 0.2 wt % of rGO-Co3O4 nanofluids, the viscosity and density increased by 70.83%, and 0.47%, respectively, while the specific heat decreased by 0.17% at a temperature of 60 degrees C over the base fluid data. The receiver pipe energy balance equations are solved using MATLAB software. With the use of 0.2 wt% of hybrid nanofluid, the mean thermal efficiency enhanced by 2.75%-31.95%, the mean exergy efficiency improved by 23.67%-2.27%, and the mean temperature increased by 9.42 degrees C, while, the receiver pipe temperature decreased by 2.69 degrees C. In addition, the mean heat transfer coefficient, mean thermal conductivity, Nusselt number, and the performance evaluation criteria were improved by using rGO-Co3O4/water nanofluid at 0.2 wt % by 309.67%, 19.31%, 254.75%, and 240.92%, respectively, while the mean entropy generation and electrical energy consumption decreased by 59.48% and 20.30%, respectively, as the CO2 emission mitigation was 253.94 kg. (C) 2020 Elsevier Ltd. All rights reserved.