Influence of inner wall roughness of supersonic separator on non-equilibrium condensation of CO₂ benefiting flue gas decarbonization

Supersonic separators are energy efficient and environmental separation device. Recent work has demonstrated the potential of supersonic separators to separate CO₂ from flue gas. Because the supersonic flows in the separator is accompanied by shock waves and non-equilibrium condensation, the current cognition level on flow behavior in the separator is low. This work establishes a numerical model to describe the high-speed two-phase flows in the separator and the non-equilibrium condensation of CO₂ during carbon capture process, and clarify the influence of inner wall roughness on carbon capture process. The results show that the rapid expansion of gas pushes the thermodynamic system to non-equilibrium state and promotes the spontaneous condensation of CO₂. Wall roughness has obvious influence on normal shock wave position, non-equilibrium condensation and normal shock wave intensity. When the roughness height increases by 0.1 mm, the maximum droplet radius in the separator decreases by 17.4%, liquid CO₂ fraction decreases by 49.1%, and radial range of liquid phase decreases by 46.3%.