Effects of chemical absorption on mass transfer from single carbon dioxide bubbles in aqueous sodium hydroxide solution in a vertical pipe
Mass transfer rates kL of single carbon-dioxide bubbles with chemical absorption in a vertical pipe were investigated using aqueous sodium hydroxide solutions. The pH of the solution was varied from 12 to 13.15. The pipe diameter D was 12.5 mm. The bubble diameter d was varied for 0.4 < d/D < 1.4 to cover various bubble shapes. The enhancement factor, E, which is the ratio of kL with and without chemical absorption, was almost unity for pH < 12.25. Then E increased with increasing pH and d for pH > 12.25. Its magnitude was, however, lower than the estimation by the two-film theory. An E correlation was developed. Good estimation of the Sherwood number for bubbles with chemical absorption was obtained by combining the E correlation and the Sherwood number correlations for bubbles without chemical absorption. Applicability of the correlations to bubbles in a larger pipe diameter was also examined.
CO bubble 2
Sodium hydroxide (NaOH)