TY - JOUR
T1 - Investigating a Stirred Bioreactor
T2 - Impact of Evolving Fermentation Broth Pseudoplastic Rheology on Mixing Mechanisms
AU - Sadino-Riquelme, M. Constanza
AU - Rivas, José
AU - Jeison, David
AU - Donoso-Bravo, Andrés
AU - Hayes, Robert E.
N1 - Funding Information:
Funding: This research was partially funded by ANID-Chile (FONDECYT/1180498). M.C Sadino-Riquelme was funded by ANID-Chile Doctoral Scholarship (Becas Chile/72180040). Dr. David Jeison acknowledges the support provided by CRHIAM center (ANID/FONDAP/15130015). Additional funding was provided by NSERC.
Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2022/3
Y1 - 2022/3
N2 - The culture medium in many fermentations is a non-Newtonian fluid. In bacterial alginate batch production, the broth becomes more pseudoplastic as the alginate concentration increases, which impairs the mixing process. This work characterizes the effect of the interaction between changing broth rheology and impeller mixing on a bioreactor fluid dynamics. Experimentally, a fermentation with evolving broth pseudoplastic rheology is reproduced. Three fermentation stages are mimicked using appropriate solutions of water and xanthan gum. Impeller torque measurements are reported. The weakening of the impellers’ interaction over the fermentation process is identified. To overcome the experimental limitations, CFD is applied to study the evolution of the fermentation fluid flow patterns, velocity field, dead zones, and vortical structures. Precessional vortex macro-instabilities are identified as being responsible for the unstable flow patterns identified at the earlier stages of the fermentation. A stable parallel flow pattern accounts for the weakest impellers’ interaction at the final stage. Overall, this work contributes with a complete workflow to adapt CFD models for characterization and aided design of stirred tanks with changing broth pseudoplastic rheology as well as an evolving flow regime.
AB - The culture medium in many fermentations is a non-Newtonian fluid. In bacterial alginate batch production, the broth becomes more pseudoplastic as the alginate concentration increases, which impairs the mixing process. This work characterizes the effect of the interaction between changing broth rheology and impeller mixing on a bioreactor fluid dynamics. Experimentally, a fermentation with evolving broth pseudoplastic rheology is reproduced. Three fermentation stages are mimicked using appropriate solutions of water and xanthan gum. Impeller torque measurements are reported. The weakening of the impellers’ interaction over the fermentation process is identified. To overcome the experimental limitations, CFD is applied to study the evolution of the fermentation fluid flow patterns, velocity field, dead zones, and vortical structures. Precessional vortex macro-instabilities are identified as being responsible for the unstable flow patterns identified at the earlier stages of the fermentation. A stable parallel flow pattern accounts for the weakest impellers’ interaction at the final stage. Overall, this work contributes with a complete workflow to adapt CFD models for characterization and aided design of stirred tanks with changing broth pseudoplastic rheology as well as an evolving flow regime.
KW - Computational fluid dynamics
KW - Dynamic rheology
KW - Fluid dynamics
KW - Mixing mechanisms
KW - Non-Newtonian fluid
KW - Vortical structures
UR - http://www.scopus.com/inward/record.url?scp=85125960465&partnerID=8YFLogxK
U2 - 10.3390/fermentation8030102
DO - 10.3390/fermentation8030102
M3 - Article
AN - SCOPUS:85125960465
VL - 8
JO - Fermentation
JF - Fermentation
SN - 2311-5637
IS - 3
M1 - 102
ER -