Effect of Nanoparticles on the Degradation, Ageing and other Properties of Ester-based Nanofluids

Vegetable-based natural esters serve the dual purpose of insulating and cooling electrical transformers as a natural alternative to conventional mineral oils. The factory-functionalized SiO2 nanoparticles were dispersed into purified cotton seed oil methyl ester to produce a nanofluid with excellent electrical and thermal properties. A dispersion method was used to prepare the nanofluids with 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8 wt. % nanoparticles into the ester at 0.1 wt. % increments. Scanning electron microscopy (SEM) coupled with electron dispersive X-ray (EDX) analysis was performed on the nanoparticles to determine their morphology and elemental composition. This study compares the results of testing samples of mineral oil, ester, and SiO2-based nanofluids before and after aging to determine their water content, flash point, pour point, dynamic viscosity, density, dielectric loss, permittivity, and breakdown strength. The results showed that CNF5 (Ester + 0.5 wt. % SiO2) performs better even after the samples have aged, owing to the addition of 0.8 wt. % SiO2 nanoparticles. CNF5 outperformed the other samples of nanofluid in terms of both thermal and dielectric properties. For CNF5, it was observed that the breakdown voltage, flash point, dynamic viscosity, tan delta, pour point, and water content decreased after ageing. It was also found that the cottonseed oil-based nanofluid improved the electrical and thermal properties more than mineral oil as nanoparticles were added to the samples.