Abstract

Improvement of heat transfer in transformer cooling system is of great importance due to its high performance, efficiency and life time dependence on reducing oil temperature inside it. This research was carried out at the request of Iran Transfo Zanjan company in order to study and improve heat transfer in radiators of power transformers. Due to the construction constraints in the company, it is not possible to make major changes to the radiator structure. Therefore, in this study, using the Ansys-Fluent software, the effect of cross-section geometry of the oil passage channels and the shape of the radiator blades as well as the effect of cooling air flow velocity were investigated and then redesigned for radiators. Based on the principles of fluid mechanics and heat transfer theory to convert laminar to turbulent and the theory of boundary layer theory Geometry 2 instead of existing geometry (Geometry 1) was presented which was achieved by two pieces of oil passage channels for overall radiator improvement. The results show that while the cooling air pressure drop in Geometry 2 increases by about 30% compared to Geometry 1, the average Nusselt number is about 16% more achievable in Geometry 2 under the same boundary conditions.