Effect of particle concentration and temperature on the thermo-physical properties of ethylene glycol–water mixture based boron nitride nanofluids

Abstract

Present article focusses on the thermal and rheological characteristics of ethylene glycol–water mixture (volume = 60/40) based boron nitride (h-BN) nanofluids measured at different volume concentrations (0.5–2 vol% h-BN) between temperatures 30–60 °C. X-ray diffraction and TEM analysis have confirmed the hexagonal structure of h-BN nanoparticles and the size range of the nanoparticles is within 90–170 nm. To optimize the ultrasonication time, the thermal conductivity of h-BN nanofluids has been monitored after each 30 min of sonication until a maximum thermal conductivity increase is achieved. The thermal conductivity of h-BN nanofluids shows an increasing trend with respect to particle concentration. Also, the thermal conductivity enhancement exhibits a temperature independent nature. The viscosity studies carried out over a shear rate of 0.612–122 s−1 revealed an increasing trend with the increasing concentration of h-BN loading. For all the volume concentrations, at lower shear rates, the viscosity initially decreased, displaying a non-Newtonian nature, and with a further increase in shear rate, the viscosity stays constant exhibiting a Newtonian nature. Based on the experimental outcomes, a correlation is introduced. The correlation showed a strong agreement with the current results, with an R2 value of 0.99.