Research On Heat Exchangers Of Oil-immersed Transformer

When oil-immersed power transformers operate, their windings and iron cores incur losses which lead to thermal energy transferring into oil and box wall; thus, temperature of windings, iron cores and oil layer rise. Because high temperature will decrease the longevity of transformers in normal use, it is necessary to control the increase of temperature by heat exchangers.Slice heat exchanger is the mainstream. It is important to find a way that would enhance the capability of heat transfer, raise exchangers' lives and decrease the cost of producing.In order to find that way, we do some researches which will be reported by this thesis. Firstly, we analyze theoretically to find a direction. To improve the heat transfer efficiency of ONAN exchangers attributes to the increase of oil layer's performance, which relies to a series of experiments.In addition, when the number of slices is large, the environment of the fins which are far away from the transformer is the best. Assuming that the flow rate of all channels of fins would be identical, the oil in the fins discussed above will be cooled more quickly and then the viscosity of it will also increase significantly. In the view of heat transfer, some areas will be waste; in the view of flow, the resistance of movement will rise. If the height of the fins which have a long distance from transformers can be reduced, the problem will be solved. Both the flow and heat transport will benefit from this solution. Considering the uncertainty of this solution and the costs of experiments, we choose numerical simulation instead to examine its feasibility. The result reveals that this method has some effect.