Loading different sizes of titania nanoparticles into transformer oil: A study on the dielectric behavior

TiO2 (titania) nanoparticles (NPs) were successfully synthesized by the sol–gel route with different calcination temperature varied from 300 to 500 °C. The microstructure and morphology of the synthesized samples were characterized under the effect of changing the calcination temperature using X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM). The result obtained from such characteristic tools confirmed the formation of the anatase phase for all the synthesized titania NPs with pronounced dependence of size and agglomeration of particles on the used calcination temperatures. Various nanofluids systems from a commercially mineral oil and the synthesized TiO2 NPs were fabricated with different concentrations up to 5 g/L from each of the synthesized NPs. The dielectric properties of the fabricated nanofluids were examined by studying the effect of the concentration of titania NPs on the variation of ac breakdown voltage and dielectric constant (e′). All the prepared oil transformer-nanofluid based on the investigated concentrations of the synthesized TiO2 NPs exhibited enhancement in the ac breakdown voltage reaching 111.8% for nanofluid with concentration 0.7 g/L based on T400 sample more than that obtained for the pure oil transformer. The dependency of e′ on NPs concentration was studied under different applied frequency values from 30 Hz to 1 MHz. The nanoparticle features were reflected on the behavior of e′ with NPs concentration throughout the investigated range of the applied frequency.