Properties of glycerol and ethylene glycol mixture based SiO2-CuO/C hybrid nanofluid for enhanced solar energy transport

Hybrid nanofluids are a novel class of colloidal fluids which have drawn significant attention due to potential tailoring of their thermo-physical properties for heat transfer enhancement by a combination of more than one nano-additive to meet specific requirements of an application. In the present work, ceramic copper oxide/carbon (SiO2-CuO/C) nanoparticles in 80:20 (wt) composition were prepared by ultrasonic-assisted wet mixing technique. The hybrid nanofluid was formulated by dispersing the nanoparticles into a base fluid mixture of 60:40 ( by mass) glycerol and ethylene glycol (G/EG) using the two-steps method. The influence of nanoparticles on the augmentation of specific heat, thermal conductivity and viscosity was examined in the volume concentration range of 0.5�2.0 in the temperature range of 303.15�353.15 K. The results demonstrate that the synthesized SiO2-CuO/C hybrid nanoparticles enhanced the thermo-physical properties of the base fluid mixture which is higher than using SiO2 alone. In the case of SiO2�G/EG nanofluid, the specific heat capacity decremented by a maximum value of 5.7 whereas the thermal conductivity and viscosity incremented by 6.9 and 1.33-times as compared with G/EG at maximum volume concentration of 2.0 at a temperature of 353.15 K. Comparatively, a reinforcement of 80 SiO2 with 20 CuO/C in G/EG mixture led to thermal conductivity and viscosity enhancement by 26.9 and 1.15-times, respectively with a significant reduction of specific heat by 21.1. New empirical correlations were proposed based on the experimental data for evaluation of thermophysical properties. © 2017 Elsevier B.V.