title: Experimental and CFD-PBM Study of Oxygen Mass Transfer Coefficient in Different Impeller Configurations and Operational Conditions of a Two-Phase Partitioning Bioreactor.
abstract: In this work, gas dispersion in a two-phase partitioning bioreactor is analyzed by calculating volumetric oxygen mass transfer coefficient which is modeled using a commercial computational fluid dynamics (CFD), code FLUENT 6.2. Dispersed oxygen bubbles dynamics is based on standard "k-ε" Reynolds-averaged Navier-Stokes (RANS) model. This paper describes a three-dimensional CFD model coupled with population balance equations (PBE) in order to get more confirming results of experimental measurements. Values of kLa are obtained using dynamic gassing-out method. Using the CFD simulation, the volumetric mass transfer coefficient is calculated based on Higbie's penetration theory. Characteristics of mass transfer coefficient are investigated for five configurations of impeller and three different aeration flow rates. The pitched six blade type, due to the creation of downward flow direction, leads to higher dissolved oxygen (DO) concentrations, thereby, higher values of kLa compared with other impeller compositions. The magnitude of dissolved oxygen percentage in the aqueous phase has direct correlation with impeller speed and any increase of the aeration magnitude leads to faster saturation in shorter periods of time. Agitation speeds of 300 to 800 rpm are found to be the most effective rotational speeds for the mass transfer of oxygen in two-phase partitioning bioreactors (TPPB).
authors.affiliation: Chemical Engineering Department, Sahand University of Technology, P.O. Box 513551996, Sahand New Town, Tabriz, Iran. h_moradkhani@sut.ac.ir.
authors.forename: Hamed
authors.initials: H
authors.lastname: Moradkhani
authors.affiliation: Department of Chemical and Petroleum Engineering, University of Tabriz, P.O. Box 5166616471, Tabriz, Iran.
authors.forename: Mir-Shahabeddin
authors.initials: MS
authors.lastname: Izadkhah
authors.affiliation: Department of Chemical Engineering, Tabriz Branch, Islamic Azad University, P.O. Box 5157944533, Tabriz, Iran.
authors.forename: Navideh
authors.initials: N
authors.lastname: Anarjan
mesh_terms: D057919:Biological Oxygen Demand Analysis / Q000379:methods; D019149:Bioreactors; D003470:Culture Media / Q000737:chemistry*; D004735:Energy Transfer; D005740:Gases / Q000737:chemistry*; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry*; D012212:Rheology / Q000379:methods*
chemical_list: D003470:Culture Media; D005740:Gases; D010100:Oxygen
keywords: Aeration; CFD; Experimental; Impellers; Oxygen mass transfer coefficient; PBM