Oxygen transfer in non-newtonian fluids stirred with a helical ribbon screw impeller

Tecante, Alberto; Fuente, E. Brito de la; Choplin, Lionel; Tanguy, P. A.

doi:10.1016/b978-088415497-6/50017-6

Cited by 3 publications

(5 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For non-coalescent electrolyte solutions, close agreement are found between Linek and Van't [4] model for fluids mixed by a solitary Rushton turbine. Again, higher oxygen transfer performance by HRI mixing is registered for 0.5 M Na 2 SO 4 with an average of 78% increased in k L a [3] model for helical screw and ( ): Arjunwadkar et al [8] Judging from the flow pattern, the novel HRI design and helical screw falls under axial dispersion category. Under shear thinning fluid scenario, the particular flow pattern was predicted to fare better in mixing viscous 0.2% w/v CMCNa than the two radial flow-type Rushton fixtures when the impeller power draw started to exceed 800 W m −3 .…”

Section: Discussionmentioning

confidence: 94%

“…The only available correlation in literature with particular relevance to proximity type agitator were derived for CMCNa solutions stirred with a helical screw impeller [3] . Van't [4] model for water, ( ) Present study for distilled water, ( ): Van't [4] model for electrolyte salt, ( ): Linek et al [7] model for electrolyte salt, ( ): Present study for electrolyte salt and (ο): Linek et al [7] model for three Rushton turbines in electrolytes salt As for open type stirrers, Van't [4] generalized correlations are well established for non-viscous fluid systems while Linek et al [7] correlated k L a specifically for 0.5 M Na 2 SO 4 system.…”

Section: Discussionmentioning

confidence: 99%

“…Van't [4] model for water, ( ) Present study for distilled water, ( ): Van't [4] model for electrolyte salt, ( ): Linek et al [7] model for electrolyte salt, ( ): Present study for electrolyte salt and (ο): Linek et al [7] model for three Rushton turbines in electrolytes salt As for open type stirrers, Van't [4] generalized correlations are well established for non-viscous fluid systems while Linek et al [7] correlated k L a specifically for 0.5 M Na 2 SO 4 system. Most correlations on oxygen transfer for viscous pseudoplastic CMC lack the level variation of apparent viscosity due to anomalous rheological nature of simulant media with the agitator shearing rate [3,15,20] . As such, there is conspicuous omission of η a term in the collection of k L a models for Rushton turbine listed in Table 4.…”

Section: Discussionmentioning

confidence: 99%

“…Tecante et al [3] had perceived that the effectiveness of axial flow close clearance impeller to be strongly dependent on gassing rate rather than the specific power uptake (agitation intensity) in viscous pseudoplastic system, which is an obvious inverse from the established correlations for radial flow Rushton turbine. By obtaining a slightly similar exponent index for P g /V variable with the aforementioned work and noting that the exponent for U g in this study to be 1.5 times more influential than value recorded for P g /V (Eq.…”

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

Modeling of Oxygen Transfer Correlations for Stirred Tank Bioreactor Agitated with Atypical Helical Ribbon Impeller

Mohamed¹

2009

American Journal of Applied Sciences

View full text Add to dashboard Cite

Problem Statement: Mixing filamentous fungi entails delicate balance between promoting high volumetric oxygen transfer coefficient (k L a) while keeping low hydrodynamic stresses in the microenvironment of cultures. This study examined the oxygen transfer capability of a prototype low shear helical impeller as a potential replacement for the standard Rushton turbine. Approach: The dependence of k L a upon specific power uptake, superficial gas velocity and apparent viscosity were examined under coalescent, non-coalescent and viscous pseudoplastic fluids scenario using dynamic gassing out technique. Subsequently, collected data were treated under historical data design of response surface methodology. Results: Three empirical power law k L a correlations were developed for each fluid. Correlation comparison with literature models for single turbine agitation suggest higher k L a augmentation within 1.5-3.6 folds for helical impeller in distilled water and as high as 78% improvement in electrolytes fluid. However impeller performance is comparatively 10% lower against theoretical k L a of triple turbines arrangement for power uptake between 0-1600 W m -3 . In case of carboxymethylcellulose, better oxygen transfer is expected for design with higher proportionality of impeller-to-tank internal diameter. Conclusions: Helical impeller performance as gas-liquid contactor is comparable to single and triple Rushtons turbines, with superficial gas velocity proved to be more influential than power uptake in non-viscous liquids and vice versa in viscous pseudoplastic fluids.

show abstract

Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling of Oxygen Transfer Correlations for Stirred Tank Bioreactor Agitated with Atypical Helical Ribbon Impeller

Mohamed¹

2009

American Journal of Applied Sciences

View full text Add to dashboard Cite

show abstract

“…Else, if the diameter ratio is higher or as found in some setup, quite close to the vessel wall to effect a scraping action, impellers are otherwise generalized as proximity type agitators [2] . Open type are primarily employed in aerobic fermentation whereas proximity types are mostly associated with the bulk blending of viscous nonNewtonian fluids [3] . As far aerobic fermentation is concerned, k L a is the yardstick for evaluating impeller performance.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Oxygen Transfer Correlations for Stirred Tank Bioreactor Agitated with Atypical Helical Ribbon Impeller

Moh¹,

Mohamad²,

Ramanan³

et al. 2009

American J. of Applied Sciences

View full text Add to dashboard Cite

show abstract

CFD simulation of stirred tanks: Comparison of turbulence models. Part I: Radial flow impellers

et al. 2011

View full text Add to dashboard Cite

A critical review of the published literature regarding the computational fluid dynamics (CFD) modelling of single-phase turbulent flow in stirred tank reactors is presented. In this part of review, CFD simulations of radial flow impellers (mainly disc turbine (DT)) in a fully baffled vessel operating in a turbulent regime have been presented. Simulated results obtained with different impeller modelling approaches (impeller boundary condition, multiple reference frame, computational snap shot and the sliding mesh approaches) and different turbulence models (standard k − ε model, RNG k − ε model, the Reynolds stress model (RSM) and large eddy simulation) have been compared with the in-house laser Doppler anemometry (LDA) experimental data. In addition, recently proposed modifications to the standard k − ε models were also evaluated. The model predictions (of all the mean velocities, turbulent kinetic energy and its dissipation rate) have been compared with the experimental measurements at various locations in the tank. A discussion is presented to highlight strengths and weaknesses of currently used CFD models. A preliminary analysis of sensitivity of modelling assumptions in the k − ε models and RSM has been carried out using LES database. The quantitative comparison of exact and modelled turbulence production, transport and dissipation terms has highlighted the reasons behind the partial success of various modifications of standard k − ε model as well as RSM. The volume integral of predicted energy dissipation rate is compared with the energy input rate. Based on these results, suggestions have been made for the future work in this area.Nous présentons un examen critique de la littérature concernant la modélisation de la dynamique des fluides numérique (DFN) de l'écoulement turbulentà une phase dans les réacteursà cuve agitée. Dans cette partie de l'examen, nous présentons les simulations de DFN de turbinesà ecoulement radial (principalement des turbinesà disque (TD)) dans un réservoir entièrement cloisonné effectuées dans un régime turbulent. Les résultats des simulations obtenus grâceà différentes approches de modélisation des turbines (couche limite turbulente, méthode des référentiels multiples, snap-shot de modélisation numérique, maillage glissant) età différents modèles de turbulence (modèle standard k-e, modèle RNG k-e, modèle aux tensions de Reynolds et simulation des grandeséchelles) ontété comparés aux données expérimentales internes d'allocation de Dirichlet latente (ADL). De plus, les modifications des modèles standards k-e récemment proposées ontégalementétéévaluées. Les prédictions du modèle (de toutes les vitesses moyennes, de l'énergie cinétique turbulente et de son taux de dissipation) ontété comparées aux données expérimentales relevéesà différents endroits de la cuve. Une discussion présente les points forts et les points faibles des modèles de DFN actuellement utilisés. Une analyse préliminaire de la sensibilité des hypothèses de modélisation liées aux modèles k-e et RSM aété menée en utilis...

show abstract

Oxygen transfer in non-newtonian fluids stirred with a helical ribbon screw impeller

Cited by 3 publications

References 16 publications

Modeling of Oxygen Transfer Correlations for Stirred Tank Bioreactor Agitated with Atypical Helical Ribbon Impeller

Modeling of Oxygen Transfer Correlations for Stirred Tank Bioreactor Agitated with Atypical Helical Ribbon Impeller

Modeling of Oxygen Transfer Correlations for Stirred Tank Bioreactor Agitated with Atypical Helical Ribbon Impeller

CFD simulation of stirred tanks: Comparison of turbulence models. Part I: Radial flow impellers

Contact Info

Product

Resources

About