Mass transfer in a single-use angled-shaft aerated stirred bioreactor applicable for animal cell culture Argang Kazemzadeh a , Cynthia Elias b , Melih Tamer b , Ali Lohi a , Farhad Ein-Mozaffari a,⇑ a Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto M5B 2K3, Canada b Sanofi Pasteur Company, 1755 Steels Avenue West, North York, Toronto M2R 3T4, Canada highlights  Performances of unbaffled angled- shaft and baffled vertical-shaft bioreactors were compared.  The lowest P/V values were attained for an unbaffled angled-shaft bioreactor.  The highest K L a values were achieved for an unbaffled angled-shaft bioreactor.  An empirical correlation for the mass transfer coefficient, K L a, was developed.  Rushton impeller was the most efficient impeller in term of the mass transfer. graphical abstract article info Article history: Received 1 September 2019 Received in revised form 8 February 2020 Accepted 28 February 2020 Available online 29 February 2020 Keywords: Bioreactors Mixing Mass transfer coefficient Animal cell culture Single-use bioreactors abstract The single-use stirred bioreactors are increasingly recognized as a viable alternative in animal cell culture due to the higher production capacity, increased flexibility, prevention of cross contamination, reduction of the cleaning cost, and shortened downtime. In this paper, the effects of the impeller speed, the volu- metric gas flow rate, and the impeller type on the volumetric gas-liquid mass transfer coefficient in a single-use unbaffled angled-shaft bioreactor applicable for the animal cell culture were analyzed and compared with those attained for the baffled vertical-shaft bioreactors. The volumetric gas-liquid mass transfer coefficient (K L a) was experimentally determined by the simplified dynamic pressure method. The lowest P/V values as well as the highest K L a values were achieved for an unbaffled angled-shaft biore- actor. It was found that the Rushton impeller was the most efficient impeller in term of mass transfer for this bioreactor. An empirical correlation for the mass transfer coefficient was also developed. Ó 2020 Elsevier Ltd. All rights reserved. 1. Introduction Bioreactors play a pivotal role in any biopharmaceutical pro- duction process and are currently considered as a main part of the animal cell culture. The performance of the bioreactor depends on various parameters such as cell line, cell culture medium, process mode, and the bioreactor design. Among these variables, the bioreactor design has a pronounced effect on the process opti- mization in cell culture growth. It means that the cell growth mostly is affected by the design of the reactor and engineering specifications rather than the bioreactor type (Doran, 2009; Zhou et al., 2009; Flickinger, 2010). During the last 60 years, many bioreactor types have been developed, but only a few types of these bioreactors such as bubble columns, airlift reactors, and stirred bioreactors or conventional bioreactors have dominated https://doi.org/10.1016/j.ces.2020.115606 0009-2509/Ó 2020 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: fmozaffa@ryerson.ca (F. Ein-Mozaffari). Chemical Engineering Science 219 (2020) 115606 Contents lists available at ScienceDirect Chemical Engineering Science journal homepage: www.elsevier.com/locate/ces