Experimental investigation on thermal conductivity and viscosity of purified aged transformer oil based SiO2, Al2O3 and TiO2 nanofluid for Electric Multiple Unit Train

Abstract

High voltage traction transformer of electric train demands reliable transformer oil with good heat transfer properties. Anyhow thermal stress due to high temperature initiates premature thermal ageing that deteriorates the properties of transformer oil even after multiple purification process. Influence of silicon dioxide (SiO 2), aluminium oxide (Al 2O 3) and titanium oxide (TiO 2) nanoparticles on treating purified aged transformer oil (PATO) has been addressed in this study. Oil samples were collected after validation process using colour condition standards. Each nanoparticle was suspended in the aged oil using magnetic stirrer and ultrasonic bath at 0.1% volume concentration. Stability analysis was conducted using photo capturing and zeta potential analyser method. Thermal conductivity and viscosity were investigated from temperature range of 30°C to 70°C. Based on the experimental results, PATO-based SiO 2 nanofluid was chosen as no sedimentation detected even after 144 hours with zeta potential value of 71.83mV. Thermal conductivity of PATO was enhanced up to 20.83%. Besides that, the suggested nanofluid obeys Newtonian fluid law with the viscosity enhancement up to 6.7%. On the other hand, it was found that the properties of PATO were improved with the suspension of SiO 2 nanoparticles, thus helps railway industry to optimize the life span of transformer oil.