Vol.:(0123456789) 1 3 Bioprocess and Biosystems Engineering (2018) 41:679–695 https://doi.org/10.1007/s00449-018-1902-7 RESEARCH PAPER Hydrodynamic performance of a single‑use aerated stirred bioreactor in animal cell culture: applications of tomography, dynamic gas disengagement (DGD), and CFD Argang Kazemzadeh 1  · Cynthia Elias 2  · Melih Tamer 2  · Farhad Ein‑Mozafari 1 Received: 20 October 2017 / Accepted: 27 January 2018 / Published online: 14 February 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract The hydrodynamics of gas–liquid two-phase fow in a single-use bioreactor were investigated in detail both experimentally and numerically. Electrical resistance tomography (ERT) and dynamic gas disengagement (DGD) combined with compu- tational fuid dynamics (CFD) were employed to assess the efect of the volumetric gas fow rate and impeller speed on the gas–liquid fow feld, local and global gas holdup values, and Sauter mean bubble diameter. From the results obtained from DGD coupled with ERT, the bubble sizes were determined. The experimental data indicated that the total gas holdup values increased with increasing both the rotational speed of impeller and volumetric gas fow rate. Moreover, the analysis of the fow feld generated inside the aerated stirred bioreactor was conducted using CFD results. Overall, a more uniform distribution of the gas holdup was obtained at impeller speeds ≥ 100 rpm for volumetric gas fow rates ≥ 1.6 × 10 −5  m 3 /s. Keywords Bioreactor · Mixing · Hydrodynamics · Computational fuid dynamics (CFD) · Electrical resistance tomography (ERT) · Dynamic gas disengagement (DGD) · Gas holdup Abbreviations Nomenclature d s Sauter mean bubble diameter (m) D Impeller diameter (m) D s Shaft diameter (m) H Vertical distance above gas distributor (m) H l Liquid height (m) H t Tank height (m) H Ib Impeller blade height (m) K Disengagement classes (dimensionless) N Impeller speed (rpm) M Corrected torque (N.m) P Power consumption (W) Re Reynolds number (dimensionless) Q g Volumetric gas fow rate (m 3 /s) t Time (s) t i Bubble rising time (s) t Ib Impeller blade thickness (m) T Tank diameter (m) V Fluid volume (m 3 ) V b Bubble volume (m 3 ) V θ Tangential velocity (m/s) u b Bubble rise velocity (m/s) w Ib Impeller blade width (m) Greek letters  l Liquid viscosity (Pa s)  g Gas viscosity (Pa s)  l Liquid density (kg/m 3 )  g Total gas holdup (dimensionless)   g Average gas holdup (dimensionless)  gi Local gas holdup (dimensionless) α Shaft angle ( ◦ ) σ Surface tension (mN/m)  1 Conductivity of contentious fuid (mS/cm)  2 Conductivity of dispersed phase (mS/cm)  mc Measured mixture conductivity (mS/cm)   mc Average measured mixture conductivity (mS/cm) π Constant * Farhad Ein-Mozafari fmozafa@ryerson.ca 1 Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto M5B 2K3, Canada 2 Sanof Pasteur Company, 1755 Steels Avenue West, North York, Toronto M2R 3T4, Canada