Thermal characterization of a nanofluid comprising nanocrystalline ZrO2 dispersed in water and ethylene glycol

Nanofluids, comprising Y2O3-stabilized (partially; 3 mol%) ZrO2 nanoparticles (up to 2 vol%) dispersed in water and ethylene glycol, were developed. A suitable surfactant and stirring routine ensured uniformity and stability of dispersion. Thermal conductivity ratio of the nanofluids, measured using an indigenously developed thermal comparator device, showed a significant increase of up to 100% with only 1.5 vol% nanoparticles. Furthermore, it was analytically shown that shape factor and aspect ratio significantly influence the effective thermal conductivity ratio of nanofluids with comparable vol% nanoparticles. The study demonstrated that a nanofluid of nano-ZrO2 dispersed in water and ethylene glycol could be usefully applied in closed-loop single-phase heat transfer conditions, such as in refrigerators or microchannels.