Thermo-fluidic performance of SiO2–ZnO/water hybrid nanofluid on enhancement of heat transport in a tube: Experimental results

Abstract

This paper reports an experimental investigation on the convective heat transfer and flow performance of silica-zinc oxide (SiO2–ZnO)/water hybrid nanofluid (HNF) flowing inside a tube with constant heat flux at different Reynolds number (Re) from 7743 to 23,228. A well-stabilized SiO2–ZnO/water HNF with 0.025–0.10weight fractions(φ) was produced via two-step method. Thermal conductivity and viscosity of HNF were measured. The convective heat transfer and flow characteristics of the HNF were determined. Thermal conductivity and viscosity of HNF showed notable enhancements as compared to water. The convective heat transfer coefficient (CHTC) of HNF enhanced with increasing φ and Re. A maximum of 29.44% enhancement in CHTC was obtained with φof 0.10 at Re = 20,131 when compared to water. Further, the friction factor and pressure drop of HNF increased with increasingφ. A maximum of 17.45% increase in friction factor and a maximum increase of 24% in pressure drop were recorded withφ of 0.10 at Re = 23,228 as compared to water. New CHTC and friction factor correlations of high accuracies (R2>90%) have been proposed. A Figure of Merit (FOM) was drawn to describe the thermal performance of HNF. Based on the analysis, the optimum thermal performance was achieved with φ of 0.10 at Re = 20,131.