A study on stability and thermophysical properties (density and viscosity) of Al2O3 in water nanofluid

Abstract

The dispersion and stability of nanofluids obtained by dispersing Al2O3 nanoparticles (obtained from different sources) in water have been analyzed. The differences arising from different dispersion techniques, the resulting particle size distribution, and time stability among the different samples are evaluated. Then the volumetric behavior up to high pressures (25 MPa) and atmospheric pressure viscosity were experimentally determined. It has been found that the influence of particle size in density is subtle but not negligible, but the differences in viscosity are very large and must be taken into account for any practical application. These viscosity differences can be rationalized by considering a theory describing the aggregation state of the nanofluid.

Determination of the packing fraction of silica nanoparticles from the rheological and viscoelastic measurements of nanofluids

“…The dispersion was performed using an ultrasonic probe (UP400s from Hielscher Company) that has been checked to be the most effective dispersion system (Pastoriza-Gallego et al, 2009;Petzold et al, 2009). Initially, the mixture of nanoparticles with the water was submitted to a sonication treatment for a period of time.…”

Characterization of halloysite-water nanofluid for heat transfer applications

“…Therefore, the use of carbon nanotubes is limited by its high viscosity. Hence, the combined study of thermal properties (thermal conductivity and specific heat) and rheological properties (viscosity) is of great importance, although only few works include rheological measurements of nanofluids (Lee et al, 2008;Pastoriza-Gallego et al, 2009Yu et al, 2012). As it was done for thermal conductivity, a benchmark study was carried out (Venerus et al, 2010), in order to compare the values of viscosity obtained by different researchers, when the same samples of Al 2 O 3 , SiO 2 , and Mn-Zn ferrite nanofluids were analyzed by several laboratories, at room temperature (ranging from 20 to 26°C).…”

Characterization of silica–water nanofluids dispersed with an ultrasound probe: A study of their physical properties and stability

“…Both the processing time and the energy influence the dispersion effect. It has been demonstrated that the ultrasonic probe is the most effective dispersion system due to its higher energy density that breaks the agglomerates more easily than the other mechanisms [11,14,15]. Only 2-4 minutes (depending on the conditions of the nanofluid) are needed to obtain well-dispersed suspensions.…”