Study on a Numerical Method for Calculating the Heating Process of HTS DC Induction Heater

A commercial HTS dc induction heater for aluminium billets is going to be built in Shanghai Jiao Tong University, China. To achieve an optimal design, a numerical model is proposed to accurately calculate the heating process of the billets due to induced current. The model is based on two physics fields i.e. including thermodynamics and electromagnetism. The changes of relevant parameters with increase of billet´s temperature are taken into account. In the model, the billets rotate in a dc magnetic field generated by a HTS magnet with iron cores. The induction heating power and temperature distribution inside the billets can be calculated accurately. In order to validate the calculation, a small laboratory-scale prototype dc inductive heater for aluminium billets is built. The coils are immersed in liquid nitrogen to flow higher current, and the billet is rotated by a motor. Comparison is carried out on the results of numerical model and experiment and analysis is made for the discrepancy between them. The discrepancy is acceptable for engineering applications. Finally, some examples of using the numerical model to calculate the electromagnetic behaviour for a commercial industry-scale dc induction heater are given.