Prediction of gas density effects on bubbly flow hydrodynamics: New insights through an approach combining population balance models and computational fluid dynamics

• Published in: AIChE journal Vol. 64; no. 10; pp. 3764 - 3774
• Main Authors: Hecht, K. J., Krause, U., Hofinger, J., Bey, O., Nilles, M., Renze, P.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-10-2018; American Institute of Chemical Engineers
• Subjects: Aerodynamics; bubble columns; Bubbles; Coalescence; Coalescing; Computational fluid dynamics; computational fluid dynamics (CFD); Computer applications; Computer simulation; Fluid dynamics; Fluid flow; Fluid mechanics; Gas density; Gases; Helium; Hydrodynamics; Mathematical models; Multiphase flow; Organic chemistry; Pipes; Population balance models
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.16336

Detailed measurements and computational fluid dynamics (CFD) investigation of the hydrodynamics in a bubble column containing internal features causing flow disturbances are presented for both air and helium gases. An optical needle probe has been used to measure profiles of bubble size, bubble velocity, and gas holdup at different locations across the cross section of the column. An approach combining CFD with population balances is able to represent observed multiphase flow phenomena such as the effect of the pipes to remix and redistribute the gas as well as the tendency of the gas to channel through a slit in the pipes rather than go around the pipes. The comparison of CFD simulation to experimental measurements reveal that the overall decrease in gas holdup observed when switching from air to helium gas can be explained by swarm effects, whereas the steeper decrease in the gas holdup profile across the column is due to coalescence effects. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3764–3774, 2018