Improvement of the cooling process of oil-immersed electrical transformers using heat pipes

A system to improve the cooling process of oil-immersed electrical transformers based on heat pipes is presented. The methodology used considers a theoretical analysis to predict the oil critical regions from the heat transfer point of view, and an experimental work to validate the theoretical predictions and to determine the effects of heat pipes installed in critical regions of the oil. The theoretical analysis of a 75-kVA electrical transformer is chosen as the physical model, whose thermal and fluid dynamic behaviors are described by a two-dimensional mathematical model. The experimental work is accomplished in a system built to simulate the heat generation due to energy losses. This unit is able to work with or without the heat pipes. Results obtained for the time evolution of the temperature distribution in the cooling fluid show a good agreement between theoretical and experimental predictions, and positive effects of the heat pipes mission.