Thermophysical Evaluation of Silica Nanoparticles in Refrigerant Compressor Oil for Enhanced Refrigeration Performance

The thermo-physical properties of nanolubricants are essential for assessing their suitability in refrigeration systems.This study uses a two-step method to explore the preparation and characterization of a novel nanolubricant by dispersing SiO2 nanoparticles into compressor lubricants.The composition of SiO2 was analyzed via SEM-EDS and FTIR, while XRD confirmed its amorphous nature.Density, viscosity, and thermal conductivity were measured at room temperature for SiO2 nanoparticles suspended in mineral and synthetic oils at different fractions (0.1%, 0.3%, 0.5%, and 0.7%) by volume.Performance improvements were compared to base lubricants.Results indicate that increasing SiO2 concentration enhances density, viscosity, and thermal conductivity in both lubricant types.The highest density occurs at a 0.7% volume fraction, reaching 819.83 kg/m (mineral) and 861.22 kg/m' (synthetic).The peak viscosity is also observed at 0.7%, measuring 36.97 mPa s (mineral) and 65.39mPa s (synthetic).For synthetic nanolubricants, the maximum density increase (5.29%) appears at 0.3%, while viscosity rises by 77.81% at the same fraction.Thermal conductivity peaks at 0.7%, with values of 0.1105 W/m K (mineral) and 0.1375 W/m K (synthetic), achieving a 26.12% increase at 0.5%.The superior performance of synthetic nanolubricants over mineral ones suggests that they may enhance the efficiency of refrigeration systems.