Numerical modelling of thermal processes in an electrical transformer dipped into polymerised resin by using commercial CFD package fluent

This paper discusses a numerical model of the heat dissipation processes in an electrical transformer dipped into polymerised resin. The transformer is cooled by both natural convection (via the ambient air) and forced convection (via the water cooling system attached to the bottom wall). In order to improve the modelling of the natural convection problem, an independent geometrical model of the surrounding air was created and considered separately. The continuity of temperature and heat flux along the interface between transformer and air was enforced by an iterative procedure. This procedure allowed one to calculate and then prescribe local heat fluxes to the external walls of the transformer. The numerical results obtained with the present model were compared to those for the transformer with prescribed average values of the boundary conditions.