Numerical examination of the evaporation process within a vacuum induction furnace with a comparison to experimental results

Abstract

This paper discusses a mathematical model for and presents the experimental results of the metal evaporation process in a vacuum induction furnace. An in-house-developed coupling procedure was utilized to predict the electromagnetic, flow and temperature fields in a simplified axisymmetric domain. Evaporation kinetics were simulated by means of a Hertz-Knudsen equation and implemented as source terms in transport equations. The metal vapour above the molten metal bath was described by an additional conservation equation, with gradients of diffusion flux and evaporated metal source terms included. The diffusion flux was the solution of Fick’s law. To fully analyse the evaporation process, several numerical computations were performed to examine the influence of the input power of the inductor, the crucible position inside the copper coil and the amount of charge. The validation of the mathematical description was performed according to aluminium mass loss measurements. A comparison with the experimental results confirmed that the proposed mathematical model of evaporation kinetics can be applied to the evaporation process modelled within a vacuum induction furnace. A numerical case study allowed for the proper identification of operating conditions to intensify the evaporation process within the induction furnace. Moreover, the obtained results confirmed that even small changes in the charge temperature during the evaporation process might have a crucial influence on the evaporation rate.