A 3-D Analysis of Gas-Liquid Mixing, Mass Transfer and Bioreaction in a Stirred Bio-Reactor

Hristov, H. V.; Mann, R.; Lossev, V.; Vlaev, S. D.; Seichter, Pavel

doi:10.1205/096030801753252306

Cited by 26 publications

(18 citation statements)

References 7 publications

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“…In this case, a model involving a network-of-zones with a large number of compartments is needed to capture the partial segregation of gas and liquid phase reagents (Rahimi and Mann, 2001;Zahradnik et al, 2001;Hristov et al, 2001) and related works. Another motivation to use the torus reactor is to derive a control law for the rotational speed of the impeller from a mathematical equation, which optimizes the dynamics of mixing.…”

Section: A Torus Model For Unsteady Mixing 823mentioning

confidence: 99%

A Torus Model Containing a Sliding Well-Mixed Zone as a Way to Represent Mixing Process at Unsteady Stirring Conditions in Agitated Vessels

Dieulot

Petit

Rouchon

et al. 2005

Chemical Engineering Communications

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This article investigates the modeling of mixing phenomena occur at unsteady stirring conditions in that agitated vessels. In particular, a new model of a torus reactor including a well-mixed zone and a transport zone is proposed. The originality of the arrangement of ideal reactors developed here is due to the time-dependent location of the boundaries between the two zones. This concept is applied to a model of the positive influence of unsteady stirring condition on a homogenization process; the model avoids mass balance discontinuity during the transitions from steady to unsteady stirring conditions.To ascertain the reliability of the model proposed, experimental runs with highly viscous fluids have been carried out in an agitated tank. The impeller used is a nonstandard helical ribbon impeller, fitted with an anchor at the bottom. The degree of homogeneity in the tank is recorded using a conductivity method after a tracer injection.It is shown that, for a given agitated fluid and mixing system, the parameters of the model are easy to estimate and that modeling results are in close agreement with experimental ones. Moreover, it appears that this model allows the easy derivation of the control law, which is a great advantage when optimizing the dynamics of a mixing process.

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Section: A Torus Model For Unsteady Mixing 823mentioning

confidence: 99%

A Torus Model Containing a Sliding Well-Mixed Zone as a Way to Represent Mixing Process at Unsteady Stirring Conditions in Agitated Vessels

Dieulot

Petit

Rouchon

et al. 2005

Chemical Engineering Communications

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“…However in the very case where large concentration gradients are formed, the results are less satisfactory. Several attempts have been made to simulate a bioreactor by coupling fluid dynamics and microbial kinetics obtained from laboratory scale experiments, using either a simplified compartment model or a full multiphase CFD approach . Very often, lower substrate consumption than expected or an over‐prediction of biomass yield was observed.…”

Section: Introductionmentioning

confidence: 99%

A coupled population balance model and CFD approach for the simulation of mixing issues in lab‐scale and industrial bioreactors

2013

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Lab‐scale (70 L) and industrial scale (70 m3) aerated fermenters are simulated using a commercial computational fluid dynamics code. The model combines an Euler‐Euler approach for the two‐phase flow, a population balance model for biological adaptation to concentration gradients, and a kinetic model for biological reactions. Scale‐up at constant volumetric mass transfer coefficient is performed, leading to concentration gradients at the large scale. The results show that for a given concentration field and a given circulation time tc, the population (physiological) state depends on the characteristic time of biological adaptation Ta. The population specific growth rate (Ta≫tc) is found independent of the spatial location and closely related to the volume average concentration. Oppositely, the population specific uptake rate (Ta∼tc) is spatially heterogeneous. The resulting local disequilibria between the uptake rate and the growth rate provide an explanation for the decreased performances of poorly macromixed industrial bioreactors. © 2013 American Institute of Chemical Engineers AIChE J, 60: 27–40, 2014

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“…The use of multiblock (or “compartmental” or “zone”) models is an alternative approach. Multiblock models have been applied in many studies for the investigation of local gas‐liquid hydrodynamics in stirred tanks,3–10 although in most studies the liquid flow field is assumed to be stationary. In some recent works, multiblock models have been integrated to the CFD programs 11–14…”

Section: Introductionmentioning

confidence: 99%

Dynamic modeling of local reaction conditions in an agitated aerobic fermenter

Laakkonen¹,

Moilanen²,

Alopaeus³

et al. 2006

AIChE Journal

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A 3-D Analysis of Gas-Liquid Mixing, Mass Transfer and Bioreaction in a Stirred Bio-Reactor

Cited by 26 publications

References 7 publications

A Torus Model Containing a Sliding Well-Mixed Zone as a Way to Represent Mixing Process at Unsteady Stirring Conditions in Agitated Vessels

A Torus Model Containing a Sliding Well-Mixed Zone as a Way to Represent Mixing Process at Unsteady Stirring Conditions in Agitated Vessels

A coupled population balance model and CFD approach for the simulation of mixing issues in lab‐scale and industrial bioreactors

Dynamic modeling of local reaction conditions in an agitated aerobic fermenter

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