Abstract

Transformers are an important part of the power distribution network and their design is important in various aspects of engineering. Thermally, when the winding temperature rises above the design value, the paper insulation is destroyed, thereby reducing the life of the insulation and the transformer. The purpose of this paper is to investigate the thermal behavior of a disc-type transformer by proposing three different geometries to direct the oil towards the critical discs and adding two types of multi-walled carbon or diamond nanoparticles to the base fluid using the mixed method. The results show that the oil directing is more effective than using the nanofluid in the oil natural method in reducing the temperature of discs, so that in one of the geometries, the average temperature at the critical discs is reduced by about 6 °C for the mineral oil, while this value is about 2 °C for the oil natural of the nanofluid. Also, the simultaneous use of oil directing method and nanofluid is investigated. The results show the synergy of the integration of these two methods and the further reduction of the temperature of the discs. Examining the load capacity of the transformer in the oil directing method shows a 20% increase compared to the oil natural method. Finally, the temperature uncertainty is investigated. The results show that there is an uncertainty of about one degree in the temperature of the discs.