Effect of Titanium Dioxide (TiO2) Nanoparticle Concentration on the Thermal Conductivity and Stability of Water-Ethylene Glycol Nanofluids

Abstract

Nanofluids have attracted considerable attention for their potential use as advanced heat transfer media in various cooling applications. This study investigates the effect of titanium dioxide (TiO2) nanoparticle concentration on the thermal conductivity and stability of nanofluids. Five concentrations of TiO2 nanofluids were prepared using water-ethylene glycol (60:40) as a base fluid and polyvinylpyrrolidone (PVP) as the surfactant. The TiO2 nanoparticles were characterized by ATR-FTIR, FESEM and EDX. Thermal conductivity measurements were carried out at room temperature (28 oC) and elevated temperature (e.g. 40 °C and 60 °C). The stability of the nanofluids was evaluated through visual inspection, UV-Vis spectroscopy and dynamic light scattering analysis. The TiO2 nanoparticles displayed spherical shape and tend to form clusters with an average particle diameter of approximately 30 nm. The 0.5 wt.% nanofluid achieved the greatest thermal conductivity value of 0.748 W/m·K resulting in 49.89% thermal conductivity enhancement at 60 °C. Freshly prepared nanofluids exhibited good dispersion stability and reduced when left undisturbed for extended period. Further improvements in long term stability are required for industrial applications.