The Influence of Macroscopic Elongational Flow on Dispersion Processes in Agitated Tanks

Wille, Martin; Langer, Gert; Werner, Udo

doi:10.1002/1521-4125(200102)24:2<119::aid-ceat119>3.0.co;2-g

Cited by 9 publications

(10 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…25 However, the studies in particulate systems reveal that the particle stress caused by these impellers is higher. 13,14,26,28,36 This statement is in general agreement with the results of the present study with the exceptions of PBT-6×45°and PROPRing-h/d=0.33. The interpretation of the increased hydromechanical stress caused by axial impellers was proven to be challenging.…”

Section: Industrial and Engineering Chemistry Researchsupporting

confidence: 93%

“…Most frequently, dispersion processes in stirred tanks are performed under turbulent flow conditions. 12,13 The stress acting on particles is determined by the local turbulent velocity fluctuations over time u 2 ′ . Additionally, if there is a significant density difference between the two phases, that is, bulk fluid and particles, the mean velocities of the particles and the fluid also differ, which leads to impact stress.…”

Section: ■ Introductionmentioning

confidence: 99%

“…To interpret the particle stress in a universal way by using only the maximum to average energy dissipation rate is challenging. 13,24 To overcome this challenge, it has often been stated that apart from the maximum energy dissipation, the local distribution of energy dissipation and the local residence time of particles in the respective energy dissipation zones should be taken into consideration to assess the particle stress in stirred systems. 19,24,30 In 1996 Justen et al 18 introduced a concept known as energy dissipation circulation function (EDCF).…”

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of Impeller Geometry on Hydromechanical Stress in Stirred Liquid/Liquid Dispersions

Bliatsiou

Malik

Böhm

et al. 2018

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Hydromechanical stress is a crucial parameter for a broad range of multiphase processes in the field of (bio)chemical engineering. The effect of impeller type and geometry on hydromechanical stress in stirred tanks is important. The present study aims at characterizing conventional and new impeller types in terms of particle stress. A two-phase liquid/liquid noncoalescing dispersion system is employed, and the drop breakage is monitored in-line in a stirred tank. The published effects of agitation on drop deformation are confirmed and expanded significantly for five modified new impeller types. Radial impellers are advantageous for applications where low shear conditions are desired. A modified propeller with a peripheral ring and the developed wave-ribbon impellers present remarkable results by producing significantly low and high hydromechanical stress, respectively. The results obtained are correlated in terms of mean and maximum energy dissipation rate, as well as circulation frequency in the impeller swept volume.

show abstract

Section: Industrial and Engineering Chemistry Researchsupporting

confidence: 93%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Impeller Geometry on Hydromechanical Stress in Stirred Liquid/Liquid Dispersions

Bliatsiou

Malik

Böhm

et al. 2018

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…The fluid flow data for the bulk liquid can be measured by using contactless and contacting measurement techniques which are e.g. particle image velocimetry [ 26 , 28 , 29 ], laser doppler anemometry [ 30 ] and hot film anemometer [ 31 ]. In short, the complete 3D characterization of fluid flows in stirred bioreactors requires measurement techniques that are difficult, highly sophisticated and very time-consuming [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional (3D) evaluation of liquid distribution in shake flask using an optical fluorescence technique

Azizan

Büchs

2017

J Biol Eng

View full text Add to dashboard Cite

Background: Biotechnological development in shake flask necessitates vital engineering parameters e.g. volumetric power input, mixing time, gas liquid mass transfer coefficient, hydromechanical stress and effective shear rate. Determination and optimization of these parameters through experiments are labor-intensive and time-consuming. Computational Fluid Dynamics (CFD) provides the ability to predict and validate these parameters in bioprocess engineering. This work provides ample experimental data which are easily accessible for future validations to represent the hydrodynamics of the fluid flow in the shake flask. Results: A non-invasive measuring technique using an optical fluorescence method was developed for shake flasks containing a fluorescent solution with a waterlike viscosity at varying filling volume (V L = 15 to 40 mL) and shaking frequency (n = 150 to 450 rpm) at a constant shaking diameter (d o = 25 mm). The method detected the leading edge (LB) and tail of the rotating bulk liquid (TB) relative to the direction of the centrifugal acceleration at varying circumferential heights from the base of the shake flask. The determined LB and TB points were translated into three-dimensional (3D) circumferential liquid distribution plots. The maximum liquid height (H max ) of the bulk liquid increased with increasing filling volume and shaking frequency of the shaking flask, as expected. The toroidal shapes of LB and TB are clearly asymmetrical and the measured TB differed by the elongation of the liquid particularly towards the torus part of the shake flask.

show abstract

“…Wille et al [46] described the effect of macroscopic elongational flow on the emulsification in stirred tank. They showed that axial flow impellers yielded smaller droplets than their radial counterparts.…”

Section: Batch Wise Emulsification: Stirred Vesselmentioning

confidence: 99%

Production of starch aerogel in form of monoliths and microparticles

et al. 2020

View full text Add to dashboard Cite

Pea and amylomaize starches were used to produce aerogel in form of monoliths and microparticles. The formation of starch gel was investigated, and we showed that each starch needed a different pasting temperature for its complete dissolution. The gelation kinetics was investigated with oscillatory rheometry for both systems as a function of the starch concentration. The gelation and retrogradation temperature of the starch gel were varied and its impact on the final aerogel evaluated. The emulsion gelation was carried out batch wise in a stirred vessel with different impeller geometries, concentrations of surfactant (Span80 and PGPR) and stirring rates. A particle size prediction approach based on idealized flow (Couette, 2D hyperbolic and turbulent) during the emulsification was proposed. A semi-continuous setup for the emulsion gelation was developed in which the emulsification occurs in a single pass through a colloid mill and the gelation is triggered in-line with a counter-current heat exchanger.

show abstract

The Influence of Macroscopic Elongational Flow on Dispersion Processes in Agitated Tanks

Cited by 9 publications

References 13 publications

Influence of Impeller Geometry on Hydromechanical Stress in Stirred Liquid/Liquid Dispersions

Influence of Impeller Geometry on Hydromechanical Stress in Stirred Liquid/Liquid Dispersions

Three-dimensional (3D) evaluation of liquid distribution in shake flask using an optical fluorescence technique

Production of starch aerogel in form of monoliths and microparticles

Contact Info

Product

Resources

About