Thermal mixing during the gas stirring operation and arc heating in a steel ladle is analyzed through the modern tools of a physical model using PIV (Particle Image Velocimetry) and thermal PLIF (Planar Laser Induced Fluorescence), whose velocity and temperature fields were used to fine-tune and validate a multiphase Eulerian two-phase mathematical model. Agreement on both fluid dynamics and thermal evolution is reasonably good between experiments and the predictions obtained by the mathematical model of the physical model. The analysis coming from the numerical model validated by the physical model measurements included the thermal mixing and energy efficiency of single nozzle injection in centric and eccentric (4/5R) gas injection. It turned out that energy efficiency in the centric gas injection is 20% more efficient than in eccentric injection. Then, under the same heat flux provided, the maximum temperature of the water in the centric gas injection would be higher than the maximum temperature reached in the eccentric mode with the same gas flow rate. Good heat transfer happens when the heat source impinges in a fluid region with high circulation and turbulent dispersion.

This article demonstrates that the enthalpy-porosity technique was successfully applied to determine the melting of DRI (direct-reduced iron) and Al pellets in a liquid of the same composition under static and forced-convection bath conditions. It also confirms that this study accurately represents the entire pellet-melting process, from shell formation to complete melting. The pellet’s internal thermal gradients and movement due to molten-steel flow were calculated using a dynamic mesh. The technique was first validated using experimental data by obtaining melting curves for aluminum spheres in their own baths at different temperatures under static bath conditions. The total melting times for the aluminum spheres in their own baths were 10 s at 750 °C, 18 s at 700 °C, and 33 s at 680 °C, showing good agreement with experimental data. The melting time for the DRI pellet in the liquid steel bath at 1500 °C was 9 s with forced convection and 11 s in the static bath. This test case shows that the technique can represent, within the same domain, actual bath stirring conditions and the melting of many solid particles, as occurs in many metallurgical processes, which is the future of simulating these complex systems.