Physico-Chemical Characterization of a Multiparticle Vegetable Oil-Based Nanofluid for High Voltage Application

Abstract

Among the most significant functional elements of a high voltage system is the transformer oil (TO); usually a mineral-based oil (MO). Nonetheless, most conventional MOs have lower thermal conductivity and therefore present poor cooling performance. Furthermore, they are hazardous to the environment and non-renewable such that they keep depleting with time. The quest for a stable and eco-friendly alternative for MOs has attracted lots of research attention in the past few decades. The focus on nanofluids for next-generation high voltage (HV) application becomes imminent especially with vegetable oils being ecofriendly. This work focuses on the study of some physicochemical properties of a multi-particle nanofluid for HV application. Groundnut oil was used as the base oil from which a pure methyl ester was extracted. Ester-based nanofluids with varying percentages by weight (0.2 – 1.0 wt. %) of a blend of SiO₂ and TiO₂ nanoparticles were prepared and characterized. Favorable viscosity and density values, i.e. 2.06 mPa-s and 0.5% were recorded for nanofluids at lower loading (0.2 wt. %) and at a higher operating temperature (70 ⁰C) as compared to those of the pure ester. The average pour point value of -0.2 ⁰C was measured for the nanofluids as against -4.0 ⁰C for pure methyl ester. The obtained values placed the prepared nanofluid as a potential candidate to substitute conventional MOs in the insulation and cooling of HV equipment.