Hydrodynamic Modeling of Two-Phase Flow in the Industrial Ruhrstahl–Heraeus Degasser: Effect of Bubble Expansion Models

In an industrial Ruhrstahl–Heraeus (RH) degasser, gas bubbles can expand rapidly due to heating by the melt as well as to the significant pressure drop when they rise in the melt. A suitable model for the bubble expansion is, therefore, essential for the accurate numerical prediction of argon–melt hydrodynamics in an RH degasser. This study focuses on the evaluation and comparison of different bubble expansion models available in the literature based on a coupled computational fluid dynamics–population balance model. The simulation results show that compared with the measured results, the modified Szekely–Martins model demonstrates the suitability for treating the bubble expansion behavior and thereby simulating the argon–melt hydrodynamics in an industrial RH degasser. The flow field and bubble expansion, breakup, and coalescence phenomena are then investigated.