Impact behaviors of a single aqueous solution droplet on curved surface filler

Abstract

Chemical absorption is one of the main methods for capturing and absorbing CO2 in post-combustion flue gases. The impact behaviors of the absorbent droplets on the filler have significant effects on CO2 absorption as the absorbent is sprayed down. However, the driving mechanisms behind these behaviors are not fully understood due to the increased difficulty in the absorption tower. In the present study, we numerically investigate the impact behavior of the CO2 absorbent droplet on the curved surface filler. The developed three-dimensional model is validated by our experimental results and previous studies. The driving mechanisms are revealed by focusing on the velocity and pressure field in different stages. The influence of the surface curvature and Weber number is analyzed, with particular attention to the evolution velocity. The liquid film oscillation is characterized by its amplitude and time for different surface hydrophobicity. The results show that the spreading of the liquid film is primarily influenced by the initial inertia, while its retraction and oscillation are mainly controlled by the surface tension and viscosity, leading to a longer retraction and oscillation time. Both pressure and velocity, as well as their peaks, exhibit different distributions depending on the behaviors in different stages. This is similar to the formation of the surrounding air vortex with its center above the gas–liquid interface in different stages. Both the Weber number and the curvature have little effect on the average spreading velocity, whereas the dimensionless maximum spreading diameter vs the Weber number follows a power law dependence. The results are helpful for understanding the physical mechanisms behind the impact behaviors of the CO2 absorbent droplets on the curved surface filler.