Research On Structures And Properties Of The Tube-fin Heat Exchanger Of Large-scale Transformer

Transformer plays an important role in power system,its Reliability is directly Related to the safety of the whole electrical networks.Large-scale power transformers generate large amount of heat during operation,increasing the temperature of the cooling medium.An excessively high temperature of the cooling medium will cause the failure of the transformer,and in severe cases it will lead to a fire and then will Result in the failure of the entire power supply system.Therefore,it is of great practical significance to study the heat transfer principle of the air cooler of a transformer and find a method that can effectively enhance the heat transfer for the safe operation and development of the electrical networks.In this paper,the influence of the fin structure of the perforated and vortex generator on the heat transfer and Resistance performance of the heat exchanger is studied for a certain tube-fin heat exchanger.The Research Results can provide theoretical guidance for the practical application of tube-fin heat exchangers.The main work of the thesis is as follows:1.According to the current Research at home and abroad,the enhanced heat transfer methods were determined.A 3-D simplified calculation model of the tube-fin heat exchanger was established using by Pro/E.The structural mesh generation was operated using by ICEM,and the commercial software FLUENT was used to simulate and analyze the model.2.Based on the theory of numerical heat transfer,enhanced heat transfer and fluid mechanics,the heat exchange and Resistance performance of tube-fin heat exchanger we Re analyzed,and the comprehensive evaluation methods for enhanced heat transfer was determined.The field synergy theory and boundary layer theory were used to Reveal the heat transfer mechanism of the optimized fin structure.3.The Research Results show that under different pipeline layout and different Reynolds number,the perforated fins and the fins with vortex generator exhibit different heat transfer performances,which can be selected according to the actual project.Under the working conditions of the air cooler studied in this paper,the heat transfer coefficient of the perforated fin heat exchanger is increased by up to 69%.