Solenoidal Bi-2223/Ag induction heater for aluminum and copper billets

• Published in: IEEE transactions on applied superconductivity Vol. 15; no. 2; pp. 2356 - 2359
• Main Authors: Hiltunen, I., Korpela, A., Mikkonen, R.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.06.2005; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aluminum; ALUMINUM ALLOYS (50 TO 99 AL); Aluminum base alloys; Applied sciences; Bi-2223/Ag; BILLETS; coil optimization; Coils; Copper; Eddy currents; Electrical engineering. Electrical power engineering; Electromagnetism; Electromagnets; Electronics; Exact sciences and technology; Heaters; HEATING; HEATING EQUIPMENT; INDUCTION HEATING; Magnetic flux; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silver; Studies; Superconducting devices; Superconducting magnets; Superconductivity; Various equipment and components; Performance evaluation; Magnetic flux; Optimization method; coil optimization; Stability criterion; Induction heating; Optimal design; Finite element method; Direct current; Sequential method; Bi-2223/Ag; Electromagnetic field; Composite superconductor; High temperature superconductor; Alternating current; Magnet; System design; Superconductor device; Quadratic programming; Flux density; Heating; Extrusion; Feasibility; Eddy current; AC losses
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2005.849665

Induction heating is widely used to heat up aluminum and copper billets before extrusion. Resistive induction heating systems, which typically have the total efficiency of 50-60%, are generally used with ac current. By utilizing superconductivity, the total efficiency of induction heating system can be increased to approximately 90%. If the heating power of conventional induction heaters can be reached with a superconducting device, resistive systems could be replaced by superconducting ones, and remarkable savings would develop in the long run. In this paper the feasibility of Bi-2223/Ag induction heater is studied. A solenoidal magnet for induction heating of aluminum and copper billets is designed. Ac losses are a considerable problem in Bi-2223/Ag magnets. Thus, dc current is utilized and the eddy currents are generated by rotating the billets. Coil design aimed to maximize the heating power by maximizing the radial gradient of the magnetic flux density in the heating area. In the design procedure the optimization algorithm Sequential Quadratic Programming was coupled with electromagnetic field computation by means of Finite Element Method. The quench current of the coil was determined based on the stability analysis of conduction-cooled Bi-2223/Ag magnets.