Three‐Dimensional Observation of Single Air Bubble Breakup in a Stirred Tank

Krakau, Frederic; Kraume, Matthias

doi:10.1002/ceat.201900033

Cited by 8 publications

(4 citation statements)

References 45 publications

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“…where d i and d j were the diameter of two daughter bubbles. A squared outer tank was used to reduce optical distortion in the experiment by Krakau et al, 47,48 which however significantly reduced the clarity of the bubbles and blurred bubble boundary. As a result, some smaller daughter bubbles could not be caught, and the bubble size was miscalculated.…”

Section: Daughter Bubble Size Distributionmentioning

confidence: 99%

Experimental study on breakup of a single bubble in a stirred tank: Effect of gas density and liquid properties

et al. 2021

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Bubble breakup plays an important role in gas–liquid flows, but detailed studies are still scarce. In this work, the breakup behavior of a single bubble in a stirred tank was experimentally studied with a high‐speed camera, focusing on the effect of gas density, liquid properties, agitation speed, and mother bubble size. The bubble breakup time, breakup probability, breakup rate, and daughter bubble size distribution were determined. The internal‐flow phenomenon that the gas flowed from the smaller part to the larger part of a deformed mother bubble was observed by a high‐speed camera. The results showed that with increasing gas density, agitation speed, mother bubble size and decreasing surface tension, the bubble breakup rate and probability of equal‐size distribution significantly increased. With increasing liquid viscosity, the bubble breakup rate decreased especially in the high viscosity range. An M‐shaped daughter bubble size distribution was observed, which was consistent with our previous bubble breakup model.

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Section: Daughter Bubble Size Distributionmentioning

confidence: 99%

Experimental study on breakup of a single bubble in a stirred tank: Effect of gas density and liquid properties

et al. 2021

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“…In recent years, there were several works studies the dynamic behavior and mechanism of bubble breakage in stirred vessels (Liao and Lucas 2009, Hasan and Krakau 2017, Krakau and Kraume 2019a. Different mechanisms governing the breakage phenomenon have been proposed for bubble/drop breakage in a stirred tank.…”

Section: Introductionmentioning

confidence: 99%

“…Breakage mechanisms are dependent on different operating and design parameters such as impeller geometry and dimensions; physical properties of both continuous and dispersed phases (viscosity and interfacial tension), and the hydrodynamics (Hasan 2017, Krakau andKraume 2019a). Therefore, the wide ranges of these parameters encountered in practical applications, requires further investigation to characterize the dynamic breakage behavior for deeming optimum design and operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Effect of impeller geometry on bubble breakage and the contributions of different breakage mechanisms in a stirred tank

Alabdly

Majdi²,

Hamad

et al. 2020

Fluid Dyn. Res.

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The effect of impeller geometry on bubble breakage in a stirred tank was investigated for a range of impeller Reynolds number (Re) using a high speed imaging method. The bubble dynamic behavior and breakage mechanism were investigated for four different impeller geometries namely, two-flat blades impeller, four-flat blades impeller, four-twisted blades impeller, and two-pinned blades impeller. The performance of each geometry was investigated by determining the breakage probability and number of fragments (daughter bubbles) produced. The contributions of dominant breakage mechanisms for each geometry were specified and discussed by identifying the breakage locations relative to the impeller. Three main breakage mechanisms were observed, namely: bubble collision with the blade, bubble breakage by blade shear, and breakage by turbulent fluctuation away from the blade. The number of fragments by each breakage mechanism was specified for the entire range of Re. The four-flat blades impeller exhibited the highest breakage probability and produced the highest number of fragments. The Pinned blades gave a high performance compared to the smooth blades, especially at higher Re. This is considered to be due to the high turbulence level provided by this type of impeller. The twisted blades impeller showed low bubble breakage probability compared with the other geometries. Breakages by collision with the blades and by shearing effect resulted in a higher number of fragments compared to the breakages caused by turbulent fluctuations. The number of fragments produced by ‘collision with blade’ exhibited a higher dependence on Re than by ‘blade shear’ or by ‘turbulent fluctuations’.

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“…In turn, this significantly increases the time required to perform each experiment. However, it is noted that observation of all three dimensions has been performed, for gas bubbles in a stirred tank, by Krakau and Kraume (2019). Some important lessons has been learned from the operation of the facility.…”

Section: Repeatable and Reproduciblementioning

confidence: 99%

Single drop breakage in turbulent flow: Statistical data analysis

Herø

Forgia

Solsvik

et al. 2020

Chemical Engineering Science: X

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To improve breakage models in the population balance framework, single octanol droplet experiments have been performed in a channel flow and recorded by high-speed camera. The study investigates impact of mother drop size on the breakage time, breakage probability, average number of daughters and the daughter size distribution for known turbulence characteristics. Each breakage event is associated with an individual turbulence level, based on the local flow characteristics. A clearly defined statistical analysis is presented. Using 95% confidence intervals, the precision of each of the determined properties is described quantitatively. Furthermore, the confidence intervals are a tool for determining whether an increased number of experiments will yield a significant increase in the precision, considered against the sources of error. It is found that 35-50 breakage events are sufficient to obtain confidence intervals of desired precision.

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Three‐Dimensional Observation of Single Air Bubble Breakup in a Stirred Tank

Cited by 8 publications

References 45 publications

Experimental study on breakup of a single bubble in a stirred tank: Effect of gas density and liquid properties

Experimental study on breakup of a single bubble in a stirred tank: Effect of gas density and liquid properties

Effect of impeller geometry on bubble breakage and the contributions of different breakage mechanisms in a stirred tank

Single drop breakage in turbulent flow: Statistical data analysis

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