CFD-integrated kinetic model for high-temperature iron oxidation in multispecies reactive environments

Abstract

This paper introduces a novel model that integrates the high-temperature kinetics of iron oxidation into a CFD framework, aiming to predict oxide scale evolution in complex systems such as combustion furnaces. Considering atmospheres with O₂, CO₂, CO, H₂O, and H₂ as reactive species, the model employs CFD techniques to accurately forecast local gas composition, enabling the application of the oxidation model to each element of the iron surface. The scale evolution is represented by either linear or parabolic growth, depending on whether oxidation kinetics or ion diffusion across the scale is the limiting factor.

Simulations are conducted on an experimental reactor where low-carbon iron samples undergo oxidation in various atmospheres and temperatures (900 °C to 1200 °C). Comparisons with the measured gained mass show satisfactory agreement, particularly in oxygen atmospheres at high temperatures and regarding the linear growth predicted in 10 % CO₂ or 10 % H₂O atmospheres. The model also performs reasonably well in quaternary atmospheres, with discrepancies attributed to initial linear constants at lower temperatures. Despite these challenges, the model demonstrates favorable performance in representing the parabolic growth observed in the tests. Overall, in intricate operational scenarios with numerous parameters, the model's performance is reasonably favorable, which allows the simulation of iron oxidation in complex reactors or combustion systems.