Nanoparticle-enhanced dielectric oils for improved electrical insulation: Comparison of MgO, Al2O3, and SiO2-based dielectric nanofluids

This study provides comprehensive and quantitative assessments of the electrical insulation, viscosity, thermal conductivity, flash point, acidity, and stability of dielectric nanofluids. In the experiment, naphthenic mineral oil was chosen as the base fluid. MgO, Al₂O₃, and SiO₂ were preferred as nanoparticles. In the dielectric breakdown voltage (BDV) tests performed, increased values were observed at certain concentrations for each nanofluid, with the highest value in the SiO₂-based nanofluid being 83.47 kV at a concentration rate of 0.05 g/L. Adding nanoparticles to the base oil increased the viscosity of all suspensions. Except for MgO-based dielectric nanofluid, the flash points of other nanofluids increased as compared to pure oil. Total acid number (TAN) values, on the other hand, increased for SiO₂- and Al₂O₃-based nanofluids but decreased for MgO-based nanofluids. However, all values are quite below the standard limit of 0.25 mgKOH/g. The percentage transmittance values calculated from the ultraviolet and visible light (UV–vis) spectrophotometry results differed for each nanofluid. However, they were all lower than the base oil. In general, the results indicate that the use of dielectric nanofluids in electrical systems will be beneficial, provided that the problem of long-term stabilisation is solved.