Hydrodynamics and ozone mass transfer in a tall bubble column

Comprehensive experimental investigation of counter-current bubble column hydrodynamics: Holdup, flow regime transition, bubble size distributions and local flow properties

“…This change is explained by the effect of the liquid flow, which slows down the rise of the bubbles, leading to higher holdup: the more compact arrangement of the bubbles leads to an earlier flow regime transition (Sections 3.2 and 3.4). Our results prove that U L (countercurrent mode) has an influence on the holdup, which agrees with the findings of Otake et al (1981), Baawain et al (2007), Biń et al (2001), Jin et al (2010), Besagni et al (2014 and Besagni and Inzoli (2016a) but disagrees with Akita and Yoshida (1973). Our results are probably due to the comparable order of magnitude of the liquid and gas velocities.…”

“…Baawain et al (2007) showed that the counter-current or cocurrent operation modes influenced the holdup by approximately 5% in weight, and less than 1% in bubble size, showing that the effect observed is mainly caused by the bubble rise velocity and not only the bubble size. Biń et al (2001) showed that the holdup increases with increasing U L in counter-current mode and decreases (or remains constant) in co-current mode. The effect is more pronounced at high gas velocities, and the difference in the holdup between co-current and counter-current mode is approximately 10%.…”

“…For example, Akita and Yoshida (1973) (d c ¼0.152 m, H c ¼2.5 m) observed a negligible effect of U L (up to 0.04 m/s) in both co-current and countercurrent operations. At higher liquid velocities, the column operation influences the holdup: the co-current mode reduces the holdup (Biń et al, 2001;Chaumat et al, 2005b;Jin et al, 2007;Kumar et al, 2012;Otake et al, 1981;Pjontek et al, 2014;Shah et al, 2012;Simonnet et al, 2007), and the counter-current mode increases the holdup (Besagni and Inzoli, 2016a;Besagni et al, 2014Biń et al, 2001;Jin et al, 2010;Otake et al, 1981) as bubbles are either accelerated or decelerated by liquid motion (Leonard et al, 2015;Rollbusch et al, 2015a). Baawain et al (2007) showed that the counter-current or cocurrent operation modes influenced the holdup by approximately 5% in weight, and less than 1% in bubble size, showing that the effect observed is mainly caused by the bubble rise velocity and not only the bubble size.…”

Two-Phase Bubble Columns: A Comprehensive Review

“…Baawain et al [121], showed that the counter-current or co-current operating mode influenced ε G for about 5% of its weight, and less than 1% of its bubble size, showing that the effect observed is mainly caused by the bubble rise velocity and not only caused by the bubble size. In agreement with this explanation concerning the influence of U L on bubble motion, different studies have reported ε G decreasing in co-current operations [49,90,[122][123][124][125][126][127][128] and increasing in counter-current operations [48,49,128]. Biń et al [128] compared the three-operation mode showing that ε G increases with U L in counter-current mode and decreases or remains constant in co-current mode.…”

Influence of internals on counter-current bubble column hydrodynamics: Holdup, flow regime transition and local flow properties

“…Baawain et al (2007) concluded that the countercurrent or co-current operations influenced the holdup for approximately 5% in weight, and less than 1% on bubble size, showing that the effect observed is mainly caused by the changes in the bubble rise velocity and not only caused by the bubble size. Biń et al (2001) observed an increase in the holdup in countercurrent mode and a decrease in co-current mode. The effect is more pronounced at high gas velocity and the difference in the holdup between co-current and counter-current mode is around 10%.…”