Temperature distribution in aluminum billets heated by rotation in static magnetic field produced by superconducting magnets
Purpose - To investigate the feasibility of a novel scheme of high-efficiency induction heater for nonmagnetic metal billets which use 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 SC coil configuration, a numerical model, based on an equivalent electric network with temperature-dependent parameters, is developed. Findings - A substantial independence of the shape of the temperature profile on the angular velocity and the value of the uniform magnetic field applied, is observed. A strong temperature gradient is observed in the radial direction in the proximity of the penetration front and in the axial direction at the top and bottom surface of the billet. Small temperature gradient was observed in the central part of the billet. Research limitations/implications - The reported temperature profile is inadequate for an actual extrusion process which is desired to happen at a constant temperature. The appropriate profile along the billet length can be achieved by a suitable axial shaping of the magnetic field, through the optimization of the coil layout, whereas the undesired radial gradient can be reduced by interspacing the rotation with temperature smoothing intervals. Practical implications - The investigation of the profile of applied magnetic field and the heating procedure which allow to achieve the distribution of temperature suitable for the extrusion process can be carried out by using the present model. Originality/value - A high-efficiency induction heater for nonmagnetic metal billets using superconducting coils in a novel scheme is investigated.
superconductivity electromagnetic induction electromagnetism