Euler–Lagrange approach to model heterogeneities in stirred tank bioreactors – Comparison to experimental flow characterization and particle tracking. (29th September 2015)

• Record Type: Journal Article
• Authors: Delafosse, Angélique; Calvo, Sébastien; Collignon, Marie-Laure; Delvigne, Frank; Crine, Michel; Toye, Dominique
• Is Part Of: Chemical engineering science. Volume 134(2015)
• Page Start: 457
• Page End: 466
• Publication Date: 2015-09-29
• Subjects: Bioreactor -- Euler–Lagrange model -- Mixing -- Particle tracking -- Experimental validation; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2015.05.045
• Languages: English
• ISSNs: 0009-2509

Abstract

Abstract: The aim of this work is the validation of an Euler–Lagrange modeling approach coupling a CFD-based compartment model (Eulerian approach) and a stochastic model based on a Continuous-Time Markov Chain (Lagrangian approach). The turbulent flow structure and the mixing process in a bioreactor stirred by an axial Mixel TT impeller is characterized by PIV and tracer experiments. Comparison between experimental and numerical data shows that the CFD-based compartment model is able to reproduce accurately the spatial heterogeneities inside the bioreactor. The trajectory of a small tracer particle which perfectly follows the fluid flow is measured by optical trajectography. It is then simulated by a stochastic model which is either based on an homogeneous or on an inhomogeneous Continuous Time Markov Chain (CTMC). Comparison of residence and circulation time distributions in three zones defined inside the bioreactor shows that the inhomogeneous CTMC model predicts with an excellent accuracy the particle trajectories inside the bioreactor. The modeling approach proposed here could be an useful tool to design scale-down bioreactors in order to reproduce at lab-scale the stress levels encountered in large-scale production bioreactors and to characterize and compare different bioreactor configurations. Abstract : Highlights: A Euler–Lagrange approach, coupling a CFD/CM and a stochastic model, is proposed. The CFD/CM is based on CFD simulations of hydrodynamics of a 20 L bioreactor. The stochastic model is based on a Continuous-Time Markov Chain (CTMC). The CFD/CM predicts the mixing of an inert tracer measured by tracer experiments. The CTMC reproduces well the experimental residence/circulation time distributions.