Kinetic Analysis of Bubble Thermal Expansion in High‐Temperature Molten Steel

Abstract

The refinement of clean steel is significantly influenced by the behavior of bubbles in high‐temperature molten steel. However, the thorough examination of the thermal expansion behavior of bubbles and its effects on two‐phase flow dynamics in high‐temperature molten steel is scarce. This study investigates the thermal expansion process of low‐temperature bubbles in high‐temperature molten steel and the resulting dynamics of two‐phase flow, employing a volume of fluid model coupled with the energy equation method. The water model physics experiment investigates the rising characteristics of bubbles inside a water–air system and validates the accuracy of numerical simulations. Results reveal that bubble temperature reaches 1873 K during a 0.1 s periodic variation, exhibiting three stages: severe heating, expansion cooling, and contraction heating. The inertia of the fluid causes the bubble to overexpansion and overcontraction, and the energy conversion between the two phases causes expansion cooling and superheating (max temperature: 2642 K). A mathematical model is built to characterize the dynamic behavior of two‐phase flow and the thermal expansion behavior of gas bubbles of arbitrary initial size in molten steel.