Mass transfer analysis for CO2 bubble absorption in methanol/Al2O3 nanoabsorbents

Abstract

In this paper computational fluid dynamics (CFD) analysis is carried out to investigate CO2 bubble absorption characteristics in methanol/Al₂O3 nanoabsorbents. Bubble size, rising velocity and mass transfer rate are compared to the previous experimental results for validation. It is found that the distance traveled for each CO2 bubble increases as the concentration of Al2O3 increases, which, in consequence, increases the residence time between liquid and gas phases resulting in higher interfacial mass transfer rates. For the case of a bubble rising in the gap between walls, the wall shear stress has a major effect on the bubble diameter and rising velocity which in consequence affects the mass transfer coefficient. It is concluded that the mass transfer coefficient enhances by about 40% by adding Al₂O3 nanoparticles (0.01vol%) compared with pure methanol absorbent from the experimental and simulation results. It is also concluded that the use of nanoparticles has a higher impact on mass transfer rate than it does on mass transfer amount, which depends on the residence time and travel distance of CO2 bubbles.