Effect of oxide nanoparticles on the thermal, rheological and tribological behaviours of refrigerant compressor oil: An experimental investigation

Abstract

Oxide based nanolubricants are prepared by dispersing TiO2, SiO2 and Al2O3 nanoparticles into synthetic refrigerant compressor oil (Polyalkylene glycol) using two-step method. Thermal conductivity of nanolubricants for 0.07 to 0.6% volume fractions in the temperature range 20 °C–50 °C and rheological properties in the range 20 °C–80 °C have been investigated. The tribological characterization is performed with a four ball tribo-tester. The results show that as the volume fraction increases thermal conductivity and viscosity of nanolubricants increase. The maximum increase in thermal conductivity ratio for TiO2, SiO2 and Al2O3 nanolubricants are 1.38, 1.31 and 1.48, respectively and corresponding increase in viscosity ratios are 5.64, 10.34 and 9.71, respectively. Rheological studies show that, unlike pure lubricant, nanolubricants exhibit non-Newtonian shear thinning behaviour. The tribological test results disclose that, lubricant appended with TiO2 and SiO2 have excellent friction reduction and anti-wear properties compared to pure lubricant.