The objectives of this study are to present a comprehensive analysis of the CO2 bubble population dynamics and to investigate their effects on the CO2 absorption characteristics in nanoabsorbents (methanol with various concentrations of Al2O3 nanoparticles) with a rectangular bubble column. The population balance model (PBM) as a well-established method based on the Euler-Euler model is employed to compute the size distribution of bubbles and to account for the bubbles coalescence and breakage in multiphase flow. The coupled volume-of-fluid (VOF) method is selected to clearly capture the coalescence and breakup processes of successively rising bubbles. The results show that there is a significant influence of the leading bubble on the following one, including the increment of the velocity, the deformation of the bubble shape and the flow instability. It is also found that the critical distance at which the influences can be exerted is related to the bubble wake trailed by the leading bubble. Accordingly, five types of bubble wakes and their effects on the bubble behaviors such as the coalescence and breakup are categorized. Finally, by further analyzing the bubble behaviors in methanol with different volume fraction of Al2O3, it is found that the coalescence and breakup of bubbles are dominated by the bubble wake and enhanced by the eddy in local liquid. It is concluded that the higher concentration of nanoparticles is favorable to the bubble coalescence and breakup, which enhance the mass transfer performance by increasing the interfacial area.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. NRF-2019R1A2B5B03069991 ).
© 2019 Published by Elsevier Ltd..
- Bubble wake
- Coalescence and breakup
- Critical distance
- Eulerian-Eulerian method
- Mass transfer coefficient
ASJC Scopus subject areas
- Chemical Engineering (miscellaneous)
- Waste Management and Disposal
- Process Chemistry and Technology