Experimental investigation of rheological properties and thermal conductivity of SiO2–P25 TiO2 hybrid nanofluids

Abstract

Over many years, great efforts have been made to develop new fluids for heat transfer applications. In this paper, the thermal conductivity (TC) and viscosity of SiO2–P25 TiO2 (SiO2–P25) hybrid nanofluids were investigated for different nanoparticle volume concentrations (0.5, 1.0 and 1.5 vol%) at five various temperatures (20, 30, 40, 50 and 60 °C). The mixture ratio (SiO2:P25) in all prepared hybrid nanofluids was 1:1. Besides, pure SiO2, P25 nanofluids were prepared with the same concentrations for comparison with the hybrid nanofluids. The base fluid used for the preparation of nanofluids was a mixture of deionized water and ethylene glycol at a ratio of 5:1. Before preparing the nanofluids, the nanoparticles were analyzed with energy-dispersive X-ray analysis, scanning electron microscope, X-ray powder diffraction, and Fourier transform infrared spectroscopy. The zeta potentials of the prepared nanofluids except SiO2 nanofluids were above 30 mV. These nanofluids were visually observed for stability in many days. The TC enhancement of the hybrid nanofluid was higher than the pure nanofluid. In particular, with 1.0 vol% concentration, the maximum enhancement of SiO2, P25 and SiO2–P25 nanofluids were 7.5%, 9.9% and 10.5%, respectively. The rheology of the nanofluids was Newtonian. The viscosity increment of SiO2, P25 and hybrid nanofluids were 19%, 32% and 24% with 0.5 vol% concentration. A new correlation was developed for the TC and dynamic viscosity of SiO2–P25 hybrid nanofluid.

Comparative Study of Carbon Nanosphere and Carbon Nanopowder on Viscosity and Thermal Conductivity of Nanofluids

“…The nanofluids have been potential materials with improved electrical, optical, and thermal characteristics [ 10 ]. During the last decades, there were numerous attempts to enhance k, convective thermal transfer coefficient, and thermal transfer rate by adding nanoparticles into the base fluid [ 11 , 12 , 13 ]. The property enhancement is dependent on the type, size, shape, and concentration of nanoparticles.…”

A Novel Experimental Study on the Rheological Properties and Thermal Conductivity of Halloysite Nanofluids

“…Choi et al showed that non-metallic nanomaterials, multiwall carbon nanotubes (CNTs), in water increased the thermal conductivity up to 160% at 1% volume fraction. After that, much research on heat-transfer fluids was performed with different nanoparticles, such as aluminum [ 13 , 14 , 15 ], gold [ 16 ], copper oxide [ 17 ], CNT [ 18 , 19 ], silicon dioxide, titanium dioxide [ 20 ].…”

A CFD Study on Heat Transfer Performance of SiO2-TiO2 Nanofluids under Turbulent Flow

“…The HNs in point were considered incompressible, Newtonian, and single-phase fluids. Table 4 illustrates the density (ρ), k, dynamic viscosity (µ), and specific heat (c p ) of HNs obtained from the authors' previous study [24]. The measurements were conducted at the temperature range from 20 • C to 60 • C. Some empirical formulae in Tables 1 and 2 use the Pr numbers ratio as temperature correction.…”