Thermal analysis of a low voltage winding of a power transformer working with natural ester and mineral oil

SANTISTEBAN, A; DORELLA, JONATHAN J.; GARELLI, L.; STORTI M.; DELGADO, F

Krakow

Congreso; 6th International Conference on Contemporary Problems of Thermal Engineering. CPOTE 2020; 2020

Silesian University of Technology and AGH University of Science and Technology

In this work a thermal-hydraulic analysis of the low voltage winding of a power transformer working in ONAN mode will be performed. The study considers the thermal and hydraulic balance of the cooling loop to determine the mass flow and oil temperature at the inlet of the winding. Balance of the windings and radiator determine the boundary conditions of the model. The insulating fluid considered is mineral oil. The CFD simulations are made with a 2D axisymmetric model run with the commercial code ANSYS Fluent. Several phenomena appear in the winding, due its configuration, that affects the heat transfer in local regions, reducing the local hot-spots in regions where the oil mass flow is low. The results will be compared to those obtained when the mineral oil is replaced by a natural ester. For natural ester, the same phenomena appears with lower intensity due to the lower mass flow and the higher viscosity. The results of this study predicts lower bottom-oil temperature and higher hot-spot temperature for the natural ester compared to the mineral oil.