Stability analysis and characterization of natural ester nanofluids for transformers

The present work aims at the preparation and characterization of a stable soybean natural ester nanofluid using alumina nanofiller, as an alternative to the conventional mineral oil. Stability using UV-Vis spectrophotometer and turbidity meter for various concentrations of nanofluids is reported and analyzed. Natural ester nanofluids with 0.02 wt% nanofiller concentration shows the highest stability. AC breakdown voltage shows a 21.5 and 27.9% increase for unfilled and 0.02 wt% nanofilled natural ester, respectively, when compared to the unfilled mineral oil. An improvement of 5.4 and 14.6% in the thermal conductivity can be observed for unfilled and 0.1 wt% nanofilled natural ester, respectively, when compared to that of unfilled mineral oil.