Characterization of the Aeration and Hydrodynamics in Vertical-Wheel™ Bioreactors

Abstract

In this work, the oxygen transport and hydrodynamic flow of the PBS Vertical-Wheel MINI™ 0.1 bioreactor were characterized using experimental data and computational fluid dynamics simulations. Data acquired from spectroscopy-based oxygenation measurements was compared with data obtained from 3D simulations with a rigid-lid approximation and LES-WALE turbulence modeling, using the open-source software OpenFOAM-8. The mass transfer coefficients were determined for a range of stirring speeds between 10 and 100 rpm and for working volumes between 60 and 100 mL. Additionally, boundary condition, mesh refinement, and temperature variation studies were performed. Lastly, cell size, energy dissipation rate, and shear stress fields were calculated to determine optimal hydrodynamic conditions for culture. The experimental results demonstrate that the kL can be predicted using Sh=1.68Re0.551Sc13G1.18, with a mean absolute error of 2.08%. Using the simulations and a correction factor of 0.473, the expression can be correlated to provide equally valid results. To directly obtain them from simulations, a partial slip boundary condition can be tuned, ensuring better near-surface velocity profiles or, alternatively, by deeply refining the mesh. Temperature variation studies support the use of this correlation for temperatures up to 37 °C by using a Schmidt exponent of 1/3. Finally, the flow was characterized as transitional with diverse mixing mechanisms that ensure homogeneity and suspension quality, and the results obtained are in agreement with previous studies that employed RANS models. Overall, this work provides new data regarding oxygen mass transfer and hydrodynamics in the Vertical-Wheel bioreactor, as well as new insights for air-water mass transfer modeling in systems with low interface deformation, and a computational model that can be used for further studies.

Analytical Investigation of the Impact of Jet Geometry on Aeration Effectiveness Using Soft Computing Techniques

“…Also, compared to conventional systems, the oxygen exchange mechanism using a sputtering jet of water is a better way to add oxygen to a pool of water . Additional uses include cell bioreactor, oxygenation, and mineral-processing flotation cells. − In another industrial process that involves casting polymers and glass, enhancing the interaction between gas and liquid aeration is crucial for the effective creation of goods . Based on how much electricity is used, an aeration system’s efficiency is measured by how well it can move oxygen into liquid water.…”

Robust Bioprocess Design and Evaluation of Commercial Media for the Serial Expansion of Human Induced Pluripotent Stem Cell Aggregate Cultures in Vertical-Wheel Bioreactors

“…The Vertical-Wheel® (VW) bioreactor family used in this study for the culture of human iPSCs (hiPSCs) has become increasingly popular as a platform for research and clinical studies of various modalities and the subject of computational uid dynamic modelling and power measurement studies [5,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. This interest in the VW bioreactor stems from the unique geometry with the following features: (i) VW impeller and U-shaped vessel together promoting strong, sweeping liquid ow at the bottom of the bioreactor; (ii) oppositely oriented axial vanes creating cutting and folding uid ow for enhanced mixing; and (iii) sizeable impeller zone having a large swept volume, which together creates a relatively uniform distribution of hydrodynamic forces making it an ideal tool for stem cell culture and bioprocess design [20].…”