DC induction heating of aluminum billets using superconducting magnets

Purpose – To analyse the heating process of an aluminum billet rotating in a static magnetic field produced by superconducting coils. Design/methodology/approach – The idea is to force the billet to rotate in a static magnetic field produced by a DC superconducting magnet. Since, a static superconducting magnet has no losses, the efficiency of the system is the efficiency of the motor used. In order to evaluate the temperature distribution arising from the field profile produced by a given coil configuration, a numerical model, based on an equivalent electric network with temperature-dependent parameters, is used. Findings – The main heating parameters, i.e. heating time, total power injected and temperature difference, are evaluated for different values of angular velocity and magnetic field. The field profile suitable to meet the specifics of an industrial heating process in terms of temperature homogeneity and heating time is determined. Starting form this profile the layout of the magnet is arrived at and some considerations on the operating condition of the superconducting windings are reported. Research limitations/implications – The mechanical stress in the billet due to weight, centrifugal effects, applied torque and resonance is examined by taking into account the weakening of the material properties with the increase of temperature and the practical limits of the heating process are evaluated. Practical implications – DC induction heating of aluminum billet using superconducting magnets can be done fulfilling the specifics of the industrial processes. Originality/value – A high-efficiency induction heater for aluminum billets using superconducting coils in a novel scheme is investigated.