title: Global performance parameters for different pneumatic bioreactors operating with water and glycerol solution: experimental data and CFD simulation.
abstract: Global variables play a key role in evaluation of the performance of pneumatic bioreactors and provide criteria to assist in system selection and design. The purpose of this work was to use experimental data and computational fluid dynamics (CFD) simulations to determine the global performance parameters gas holdup ([Formula: see text]) and volumetric oxygen transfer coefficient (k L a), and conduct an analysis of liquid circulation velocity, for three different geometries of pneumatic bioreactors: bubble column, concentric-tube airlift, and split tube airlift. All the systems had 5 L working volumes and two Newtonian fluids of different viscosities were used in the experiments: distilled water and 10 cP glycerol solution. Considering the high oxygen demand in certain types of aerobic fermentations, the assays were carried out at high flow rates. In the present study, the performances of three pneumatic bioreactors with different geometries and operating with two different Newtonian fluids were compared. A new CFD modeling procedure was implemented, and the simulation results were compared with the experimental data. The findings indicated that the concentric-tube airlift design was the best choice in terms of both gas holdup and volumetric oxygen transfer coefficient. The CFD results for gas holdup were consistent with the experimental data, and indicated that k L a was strongly influenced by bubble diameter and shape.
authors.affiliation: Graduate Program of Chemical Engineering, Federal University of São Carlos, C.P. 676, São Carlos, SP, 13565-905, Brazil.
authors.forename: G Y
authors.initials: GY
authors.lastname: Rodriguez
authors.affiliation: Graduate Program of Chemical Engineering, Federal University of São Carlos, C.P. 676, São Carlos, SP, 13565-905, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Valverde-Ramírez
authors.affiliation: Graduate Program of Chemical Engineering, Federal University of São Carlos, C.P. 676, São Carlos, SP, 13565-905, Brazil.
authors.forename: C E
authors.initials: CE
authors.lastname: Mendes
authors.affiliation: Graduate Program of Chemical Engineering, Federal University of São Carlos, C.P. 676, São Carlos, SP, 13565-905, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Béttega
authors.affiliation: Graduate Program of Chemical Engineering, Federal University of São Carlos, C.P. 676, São Carlos, SP, 13565-905, Brazil. badinojr@ufscar.br.
authors.forename: A C
authors.initials: AC
authors.lastname: Badino
mesh_terms: D019149:Bioreactors; D003198:Computer Simulation; D005990:Glycerol / Q000737:chemistry*; D008956:Models, Chemical; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D005990:Glycerol
keywords: Computational fluid dynamics; Gas holdup; Global variables; Liquid circulation velocity; Oxygen transfer; Performance parameters; Pneumatic bioreactors