Mineral oil based CuO nanofluid-immersed transformers analysis concerning the efficacy of nanocrystalline alloy core in reduction of losses and HST

Abstract

Electromagnetic and thermal evaluation of transformers are required for better acquaintance with detailed and complex behaviors of the system components as well as accurate description of the corresponding magnetic and thermal performances. Hence, this paper is devoted to a comprehensive study of the impact of CuO nanoparticles on cooling performance enhancement of a three-phase transformer. Besides, as determination of proper values for heat generation rate of the transformer core is indispensable for thermal modeling, the core losses are acquired through electromagnetic modeling as an essential step. The results derived from the transformer with silicon steel core are compared with the case in which a type of nanocrystalline soft magnetic core material, Finemet, is used. In this paper, 3D simulations are performed for electromagnetic and heat transfer analysis of the transformer. The results gained for nanocrystalline core indicate its superior efficiency in lessening the core losses due to the drastic improvement found in its magnetic and thermal characteristics compared to conventional cores used in previous works. It also becomes apparent that the use of CuO nanoparticles in the pure oil as a novel approach leads to lower hotspot temperature accompanied by notable decrease in the average and maximum temperatures of the fluid. Mean heat transfer coefficients of the oil with and without nanoparticles are finally checked against experimental values to show the simulation results preciousness.