Heat Transfer Model for an RF Cold Crucible Induction Heated Melter

A method to reduce radioactive waste volume that includes melting glass in a cold crucible radio frequency induction heated melter has been investigated numerically. The purpose of the study is to correlate the numerical investigation with an experimental apparatus that melts glass in the above mentioned melter. A model has been created that couples the magnetic vector potential (real and imaginary) to a transient startup of the melting process. This magnetic field is coupled to the mass, momentum, and energy equations that vary with time and position as the melt grows. The coupling occurs with the electrical conductivity of the glass as it rises above the melt temperature of the glass and heat is generated. Natural convection within the molten glass helps determine the shape of the melt as it progresses in time. An electromagnetic force is also implemented that is dependent on the electrical properties and frequency of the coil. This study shows the progression of the melt shape with time along with temperatures, power input, velocites, and magnetic vector potential. A power controller is implemented that controls the primary coil current so that the power induced in the melt does not exceed 60 kW. The coupling with the 60 kW generator occurs with the impedance of the melt as it progresses and changes with time. With a current source of 70 Amps (rms) in the primary coil and a frequency of 2.6 MHz, the time to melt the glass takes 0.8 hours for a crucible that is 10 inches in diameter and 10 inches high.Copyright © 2003 by ASME