Prediction and evaluation of the cooling performance of radiators used in oil-filled power transformer applications with non-direct and direct-oil-forced flow

Lifetime and reliability of a power transformer are highly dependent on cooling modes as excessive heat generation is the major cause of deteriorating insulation performance. For these reasons, optimal cooling design is necessary to avoid operating faults and materials degradation due to thermal damage. This paper presents prediction and experimental study on the cooling performance of radiators used in oil-filled power transformer applications with non-direct flow (ONAN) and direct-oil-forced flow (ODAN). Radiator temperature distribution and cooling performance was predicted using theoretical calculations, then validated using CFD simulation results. In the experiment, cooling capacity was evaluated with the ONAN and the ODAN flow. For ODAN flow, the maximum cooling capacity was enhanced 20.1% more than ONAN flow. These results confirm that the prediction and the evaluation of radiator cooling performance can be applied to design optimization of cooling mode for oil-filled power transformer applications.