Analysis Of Flow And Heat Transfer Inside A Power Transformer Cooled By Nature Oil Circulation

The cooling method of nature oil circulation is not only widely used in small-middle type power transformer, but also used in large type power transformer with low load and low ambient temperature.This thesis brings some new proposals for the computation of temperature rise in nature oil transformer. Some useful formulas for convection calculation of vertical and horizontal duct are given. So temperature decrease at the surface of discs and temperature rise of oil flow can be obtained.On this basis, Fortran program is written to solve temperature and velocity fields in transformer. By using this program we can calculate total flow, duct flow, mean temperature rise of transformer oil, oil time constant, mean oil temperature rise in each winding-coil, temperature distribution in each winding-coil, and stable/ transient state temperature field. So this program has a great use value. Using the result, we can draw nephograms and curves of winding-coil temperature distribution by Microcal Origin.This numerical simulation is not limited by number of cooler, winding at each pole, directed area, and horizontal duct in each directed area, and not limited by geometrical size of discs and ducts. In addition, it is applied to the condition when cooler are placed to both sides and ipsilateral all.