Local gas holdup simulation and validation of industrial-scale aerated bioreactors

Witz, Christian; Treffer, Daniel Franz; Hardiman, Timo; Khinast, Johannes G.

doi:10.1016/j.ces.2016.06.053

Cited by 28 publications

(19 citation statements)

References 81 publications

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“…In order to detect the gas-filled cavities behind the impeller blades, and thus, the respective flow regime, a self-made 2-pole conductivity probe with small tip size was applied ( Figure 1). The probe was mounted on an in height-adjustable holder, which was moved to the respective impeller level for measurements (Witz, Treffer, Hardiman, & Khinast, 2016). The cavity size and type behind each blade were identified by a drop in the voltage pulse response of the probe.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…CFD Simulations were conducted applying the Euler-Lagrange approach of the two-phase flow as described in Witz et al (2016) and Eibl, Rustige, Witz, and Khinast (2020). The Lattice Boltzmann method (LBM) was used for simulation of the liquid flow field and the bubble movement was captured via a Lagrangian approach by solving the Newton's equation of motion with the forces fluid stresses, gravity, drag, lift and added mass forces acting on the bubbles.…”

Section: Cfd Simulationsmentioning

confidence: 99%

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Characterization of the Gas Dispersion Behavior of Multiple Impeller Stages by Flow Regime Analysis and CFD Simulations

Bernauer

Eibl

et al. 2020

Preprint

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Multiple impeller reactors are widely used due to their advanced gas utilization and an increased volumetric mass transfer coefficient. However, with the application of Rushton impellers, gas dispersion efficiency varies between the bottom and the upper impeller levels. The present study analyzes the individual flow regime, power input and gas holdup in each compartment of a reactor equipped with four Rushton impellers. The results indicate that the pre-dispersion of the air introduced by the bottom impeller plays a key role in a better gas retention efficiency of the upper impellers. In contrast, a flooded bottom impeller adversely affects the gas dispersion of all impellers. A novel analysis of the bubble flow in the dispersed state via a two-phase CFD model reveals that a more homogenous distribution of air bubbles in the upper compartments leads to high compartment gas holdup values, but fewer bubbles in the vicinity of the impellers. The measured and simulated data of this study indicate that the upper impellers' efficiency mostly depends on the flow regime of and the pre-dispersion by the bottom impeller rather than on the upper impellers' flow regimes. These results contribute to the understanding of essential mixing processes and scaling of aerated bioreactors.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Cfd Simulationsmentioning

confidence: 99%

Characterization of the Gas Dispersion Behavior of Multiple Impeller Stages by Flow Regime Analysis and CFD Simulations

Bernauer

Eibl

et al. 2020

Preprint

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“…R-probes were used to determine the void fraction distribution in various two-phase systems, such as bubble columns 3,9,11,20,21 and large diameter channels, 23 or in aerated stirred tanks, where gas-filled cavities and their structures were defined based on this detection. 6,19,24,25 Computational fluid dynamics (CFD) is an effective tool for obtaining detailed insights into the various types of fluid flows with multiple phases. In multiphase-flow industrial devices, the hydrodynamic phenomena can be observed for several time and length scales, such as macroscopic, mesoscopic, and microscopic.…”

Section: Introductionmentioning

confidence: 99%

Void fraction distribution in a bisectional bubble column reactor

2019

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This article presents the distribution of the local void fraction (α) in a mock‐up bisectional bubble column with a diameter of 0.63 m. Owing to the lack of such data in the literature, α was investigated experimentally using a microresistivity (R) probe and a phase discrimination procedure based on the probe signal. The two‐phase mixture that consisted of air and tap water was measured at 342 nodes in the vertical half‐section plane of the column. Relatively small differences between the volume‐integrated local values of α and the measured total gas holdups showed reasonably good agreement under all conditions. Experimental data were used for validation of a bubble column numerical model for a low hydrodynamic regime with commercial computational fluid dynamics (CFD) code. The difference between the CFD calculated total gas holdup and the experimentally measured mean value is 8.8%, while some differences in the local void fraction distributions were found in the lower part of the column. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1186–1197, 2019

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“…В последнее время наблюдается рост использования графических процессоров (GPU) для решения прикладных задач в различных областях науки [1][2][3][4][5][6][7]. Рекламно-маркетинговые усилия компаний-производителей графических чипов и мировая конкуренция привели к су-щественному снижению стоимости самих видеокарт, а также к снижению совокупной стои-мости владения данными аппаратными устройствами.…”

Section: Introductionunclassified

“…Использование открытого стандарта OpenCL дает возможность запус-кать одну и ту же программу, выполняющую параллельные вычисления, как на центральных многоядерных процессорах, так и на графических процессорах [10]. Несмотря на то, что реа-лизация приложений на OpenCL не зависит от типа оборудования и производителя, данный стандарт почему-то продолжительное время не привлекал особого внимания специалистов, и сейчас этот факт легко отследить по количеству статей, посвященных конкретной реализа-ции распараллеливания [1][2][3][4][5][6][7]. В связи с тем, что проведение математических вычислений на GPU становится всё бо-лее популярным, нам хотелось бы отметить два значимых нюанса применения данной техно-логии.…”

Section: Introductionunclassified

Parallelizing the solution of the nonlinear heat conduction problem with the application of the OpenCL library

Спевак¹,

Нефедова²

2016

DREAM

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The paper deals with the application of parallel computation methods to the numerical solution of the nonlinear boundary value problem for the degenerate two-dimensional differential heat conduction equation. The nonlinearity of the problem stems from the power dependence of the thermal conductivity coefficient on temperature. The solution algorithm is based on the boundary element method with the application of the dual reciprocity method enabling all the computations to be brought to the boundary of the problem solution domain. A program has been developed from the presented computational algorithm. To accelerate the computation as much as possible, we use parallel programming processes and graphics processors. The program is written in the С++ programming language with the use of the OpenMP and OpenCL open standards. An example is considered to illustrate the work of the algorithm and the program; the calculation accuracy and the calculation speed are analyzed. Keywords: parallel computation, OpenMP, OpenCL, nonlinear heat conduction problem, boundary element method, analytical integration, radial basis functions.DOI: 10.17804/2410-9908.2016.6.080-091 References 1.Aguilar-Leal O., Fuentes-Aguilar R.Q., Chairez I., Garcia-Gonzalez A., Huegel J.C. Distributed parameter system identification using finite element differential neural networks. Applied Soft Computing, 2016, vol. 43, pp. 633-642. DOI: 10.1016/j.asoc.2016 Petaccia G., Leporati F., Torti E. OpenMP and CUDA simulations of Sella Zerbino Dam break on unstructured grids. Computational Geosciences, 2016, vol. 20, no. 10, pp. 1123-1132. DOI: 10.1007. Sundarapandian M., Kalpathi R., Siochi R.A.C., Kadam A.S. Lung diaphragm tracking in CBCT images using spatio-temporal MRF.

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Local gas holdup simulation and validation of industrial-scale aerated bioreactors

Cited by 28 publications

References 81 publications

Characterization of the Gas Dispersion Behavior of Multiple Impeller Stages by Flow Regime Analysis and CFD Simulations

Characterization of the Gas Dispersion Behavior of Multiple Impeller Stages by Flow Regime Analysis and CFD Simulations

Void fraction distribution in a bisectional bubble column reactor

Parallelizing the solution of the nonlinear heat conduction problem with the application of the OpenCL library

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