Hydrodynamics characterization of a choanoid fluidized bed bioreactor used in the bioartificial liver system: Fully resolved simulation with a fictitious domain method--颗粒学报PARTICUOLOGY

Sun, J., Yu, Z., & Ye, S. (2017). Hydrodynamics characterization of a choanoid fluidized bed bioreactor used in the bioartificial liver system: Fully resolved simulation with a fictitious domain method. Particuology, 32, 39-48. https://doi.org/10.1016/j.partic.2016.07.010

Hydrodynamics characterization of a choanoid fluidized bed bioreactor used in the bioartificial liver system: Fully resolved simulation with a fictitious domain method

Jingyuan Sun ¹, Zhaosheng Yu ^*, Shangjun Ye

Department of Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, China

10.1016/j.partic.2016.07.010

Volume 32, June 2017, Pages 39-48

Received 23 March 2016, Revised 8 June 2016, Accepted 22 July 2016, Available online 10 January 2017, Version of Record 20 April 2017.

E-mail: yuzhaosheng@zju.edu.cn

Highlights

• Hydrodynamic performance of a bioartificial liver fluidized bed reactor was evaluated.

• Direct-forcing/fictitious domain method was used for fully resolved simulation.

• Small increase of density ratio converted short-circuit flow to asymmetrical cycle.

• Increase of particle number enhanced stagnant zones and particle accumulation.

• Filter screens had a negative effect on particle fluidization velocity.

Abstract

Choanoid fluidized bed bioreactors (CFBBs) are newly developed core devices used in bioartificial liver-support systems to detoxify blood plasma of patients with microencapsulated liver cells. Direct numerical simulations (DNS) with a direct-forcing/fictitious domain (DF/FD) method were conducted to study the hydrodynamic performance of a CFBB. The effects of particle–fluid density ratio, particle number, and filter screens preventing particles flowing out of the reactor were investigated. Depending on density ratio, two flow patterns are evident: the circulation mode in which the suspension rises along one sidewall and descends along the other sidewall, and the non-circulation mode in which the whole suspension roughly flows upward. The circulation mode takes place under non-neutral-buoyancy where the particle sedimentation dominates, whereas the non-circulation mode occurs under pure or near-neutral buoyancy with particle–fluid density ratios of unity or near unity. With particle–fluid density ratio of 1.01, the bioartificial liver reactor performs optimally as the significant particle accumulation existing in the non-circulation mode and the large shear forces on particles in the circulation mode are avoided. At higher particle volume fractions, more particles accumulate at the filter screens and a secondary counter circulation to the primary flow is observed at the top of the bed. Modelled as porous media, the filter screens play a negative role on particle fluidization velocities; without screens, particles are fluidized faster because of the higher fluid velocities in the jet center region. This work extends the DF/FD-based DNS to a fluidized bed and accounts for effects from inclined side walls and porous media, providing some hydrodynamics insight that is important for CFBB design and operation optimization.

Graphical abstract

Keywords

Choanoid fluidized-bed bioreactor; Particle-laden flows; Direct numerical simulation; Direct-forcing/fictitious domain method; Hydrodynamic characteristics

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