AC breakdown voltage and viscosity of mineral oil based SiO<inf>2</inf> nanofluids

Abstract

A nanofluid is a fluid containing nano-sized materials. It exhibits more efficient heat transfer abilities compared to the host fluid. However the precise effect on the electrical properties of the host fluid is still uncertain. The purpose of the present study is to analyze the AC breakdown strength and viscosity of mineral oil based SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanofluids. The host fluid used in this paper is Shell Diala S3ZXIG. This type of mineral oil is widely used in HV transformers and in the power supplies of X-ray systems. The size of the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanoparticles is ranging between 10 and 20 nm. The mass fractions of the investigated nanofluids are between 0.005% and 0.02%. The influence of nanoparticle concentration and moisture content on the breakdown strength is studied. The AC breakdown test results are analyzed with Weibull statistical distributions. Viscosity is an important physical property of mineral oil, which has an effect on both the electrical and the thermal performance of mineral oil. Viscosity tests were performed with a rheology meter.