Effect of moisture and sonication time on dielectric strength and heat transfer performance of transformer oil based Al2O3 nanofluid

The dielectric breakdown strength of transformer oil plays an important role in the performance of transformers. The presence of moisture and excess heat in the transformer oil degrade its performance. In this study, the effect of moisture and sonication time on dielectric strength, stability, and heat transfer performance is investigated experimentally. Nanofluids are the colloidal homogenous suspensions, prepared by dispersing the nanoparticles (< 100 nm) in the required quantity. Nanoparticles consist of good thermo-physical properties like thermal conductivity, specific heat, etc. By dispersing nanoparticles into base fluids, nanofluid shows improved properties compared to base fluids. Al2O3 nanoparticles based nanofluid is a proven heat transfer fluid for the applications like automobile radiators, electronic cooling, nuclear cooling, etc. So, in the present study, transformer oil - Al2O3 nanofluid is considered to study the effect of moisture on the heat transfer performance and breakdown strength. Results indicated that the performance of transformer oil nanofluid was decreased with an increase in the moisture content present in it. Also, breakdown voltage and heat transfer coefficient were maximum at 0.1% volume fraction of nanofluid.