Transformer oil is usually heated by electrical heating devices, which has defects of high temperature of heating devices thus low reliability. Therefore, an electromagnetic induction heating device of circulating oil was proposed in this paper. An electromagnetic-thermal coupling model of the heating device was built, and the modeling results were verified by experiments. Using the model, the structure of heating tube of circulating oil is optimized, and temperature-velocity field synergy analysis for each tube was carried out. The results show that the alternating elliptical axis tube has better heat transfer performance and temperature uniformity than the circular or elliptic straight tube. At last, the thermal resistance networks of the electromagnetic induction heating device and the traditional electrical device were built. The thermal resistance analysis results show that the electromagnetic induction heating device has much lower temperature thus higher reliability than the traditional electrical heating device.
Keywords electromagnetic induction heating, electromagnetic-thermal coupling model, structure optimization, field synergy, thermal resistance network