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Dieter Eibl - One of the best experts on this subject based on the ideXlab platform.
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Power Input Measurements in Stirred Bioreactors at Laboratory Scale.
Journal of visualized experiments : JoVE, 2018Co-Authors: Stephan C. Kaiser, Sören Werner, Valentin Jossen, Katharina Blaschczok, Dieter EiblAbstract:The Power Input in stirred bioreactors is an important scaling-up parameter and can be measured through the torque that acts on the impeller shaft during rotation. However, the experimental determination of the Power Input in small-scale vessels is still challenging due to relatively high friction losses inside typically used bushings, bearings and/or shaft seals and the accuracy of commercially available torque meters. Thus, only limited data for small-scale bioreactors, in particular single-use systems, is available in the literature, making comparisons among different single-use systems and their conventional counterparts difficult. This manuscript provides a protocol on how to measure Power Inputs in benchtop scale bioreactors over a wide range of turbulence conditions, which can be described by the dimensionless Reynolds number (Re). The aforementioned friction losses are effectively reduced by the use of an air bearing. The procedure on how to set up, conduct and evaluate a torque-based Power Input measurement, with special focus on cell culture typical agitation conditions with low to moderate turbulence (100 < Re < 2·104), is described in detail. The Power Input of several multi-use and single-use bioreactors is provided by the dimensionless Power number (also called Newton number, P0), which is determined to be in the range of P0 ≈ 0.3 and P0 ≈ 4.5 for the maximum Reynolds numbers in the different bioreactors.
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Development of a method for reliable Power Input measurements in conventional and single-use stirred bioreactors at laboratory scale.
Engineering in life sciences, 2016Co-Authors: Stephan C. Kaiser, Sören Werner, Valentin Jossen, Matthias Kraume, Dieter EiblAbstract:Power Input is an important engineering and scale-up/down criterion in stirred bioreactors. However, reliably measuring Power Input in laboratory-scale systems is still challenging. Even though torque measurements have proven to be suitable in pilot scale systems, sensor accuracy, resolution, and errors from relatively high levels of friction inside bearings can become limiting factors at smaller scales. An experimental setup for Power Input measurements was developed in this study by focusing on stainless steel and single-use bioreactors in the single-digit volume range. The friction losses inside the air bearings were effectively reduced to less than 0.5% of the measurement range of the torque meter. A comparison of dimensionless Power numbers determined for a reference Rushton turbine stirrer (NP = 4.17 ± 0.14 for fully turbulent conditions) revealed good agreement with literature data. Hence, the Power numbers of several reusable and single-use bioreactors could be determined over a wide range of Reynolds numbers between 100 and >104. Power numbers of between 0.3 and 4.5 (for Re = 104) were determined for the different systems. The rigid plastic vessels showed similar Power characteristics to their reusable counterparts. Thus, it was demonstrated that the torque-based technique can be used to reliably measure Power Input in stirred reusable and single-use bioreactors at the laboratory scale.
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time efficient way to calculate oxygen transfer areas and Power Input in cylindrical disposable shaken bioreactors
Biotechnology Progress, 2014Co-Authors: Wolf Klöckner, Jochen Buchs, Sören Werner, Clemens Lattermann, Franz Pursche, Dieter EiblAbstract:Disposable orbitally shaken bioreactors are a promising alternative to stirred or wave agitated systems for mammalian and plant cell cultivation, because they provide a homogeneous and well-defined liquid distribution together with a simple and cost-efficient design. Cultivation conditions in the surface-aerated bioreactors are mainly affected by the size of the volumetric oxygen transfer area (a) and the volumetric Power Input (P∕VL) that both result from the liquid distribution during shaking. Since Computational Fluid Dynamics (CFD)—commonly applied to simulate the liquid distribution in such bioreactors—needs high computing Power, this technique is poorly suited to investigate the influence of many different operating conditions in various scales. Thus, the aim of this paper is to introduce a new mathematical model for calculating the values of a and P∕VL for liquids with water-like viscosities. The model equations were derived from the balance of centrifugal and gravitational forces exerted during shaking. A good agreement was found among calculated values for a and P∕VL, CFD simulation values and empirical results. The newly proposed model enables a time efficient way to calculate the oxygen transfer areas and Power Input for various shaking frequencies, filling volumes and shaking and reactor diameters. All these parameters can be calculated fast and with little computing Power. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1441–1456, 2014
Jochen Buchs - One of the best experts on this subject based on the ideXlab platform.
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molecular weight and viscosifying Power of alginates produced in azotobacter vinelandii cultures in shake flasks under low Power Input
Journal of Chemical Technology & Biotechnology, 2016Co-Authors: Karen Gomezpazarin, Celia Flores, Tania Castillo, Enrique Galindo, Jochen Buchs, Carlos PenaAbstract:BACKGROUND The aim of this study was to evaluate the viscosifying Power and mean molecular weight (MMW) of alginate synthesized by Azotobacter vinelandii in a region of very low Power Input; as well as to scale-up the process of alginate production in a 3 L fermenter using the Power Input profile (determined in shake flasks) as criterion. RESULTS In cultures developed at very low Power Input (P/V) (0.02 to 0.68 kW m−3) and maximal oxygen transfer rate (OTRmax) from to 0.85 to 2.8 mmol L-1 h-1, both the specific growth rate and alginate production were negatively affected. In contrast, the viscosifying Power of the alginate increased significantly, with respect to that obtained at the highest Power Input (1.6 kW m−3). This behavior was related to the synthesis of alginates with a high MMW (2240 kDa). When profiles of Power Input determined in shake flasks at very low P/V were reproduced in a stirred fermentor, it was possible to reproduce the same trends in both the alginate production and the polymer viscosifying Power. CONCLUSION This study provides useful information in order to implement new scale-up strategies for alginate production, exhibiting chemical characteristics and viscosifying properties superior to commercial alginates. © 2015 Society of Chemical Industry
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time efficient way to calculate oxygen transfer areas and Power Input in cylindrical disposable shaken bioreactors
Biotechnology Progress, 2014Co-Authors: Wolf Klöckner, Jochen Buchs, Sören Werner, Clemens Lattermann, Franz Pursche, Dieter EiblAbstract:Disposable orbitally shaken bioreactors are a promising alternative to stirred or wave agitated systems for mammalian and plant cell cultivation, because they provide a homogeneous and well-defined liquid distribution together with a simple and cost-efficient design. Cultivation conditions in the surface-aerated bioreactors are mainly affected by the size of the volumetric oxygen transfer area (a) and the volumetric Power Input (P∕VL) that both result from the liquid distribution during shaking. Since Computational Fluid Dynamics (CFD)—commonly applied to simulate the liquid distribution in such bioreactors—needs high computing Power, this technique is poorly suited to investigate the influence of many different operating conditions in various scales. Thus, the aim of this paper is to introduce a new mathematical model for calculating the values of a and P∕VL for liquids with water-like viscosities. The model equations were derived from the balance of centrifugal and gravitational forces exerted during shaking. A good agreement was found among calculated values for a and P∕VL, CFD simulation values and empirical results. The newly proposed model enables a time efficient way to calculate the oxygen transfer areas and Power Input for various shaking frequencies, filling volumes and shaking and reactor diameters. All these parameters can be calculated fast and with little computing Power. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1441–1456, 2014
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Power Input correlation to characterize the hydrodynamics of cylindrical orbitally shaken bioreactors
Biochemical Engineering Journal, 2012Co-Authors: Wolf Klöckner, Stéphanie Tissot, Florian M. Wurm, Jochen BuchsAbstract:Disposable cylindrical shaken bioreactors using plastic bags or vessels represent a promising alternative to stainless steel bioreactors, because they are flexible, cost-effective and can be pre-sterilized. Unlike conventional well-established steel bioreactors, however, such disposable bioreactor systems have not yet been precisely characterized. Thus, the aim of this current work is to introduce a new Power Input correlation as a potential means to characterize the hydrodynamics of these new systems. A set of rel- evant Power Input variables was defined and transformed into dimensionless numbers by using the Buckingham’s pi-Theorem. These numbers were then experimentally varied to quantify the relationship among the numbers. A simple correlation was generated for the Power Input with seven variables. The application of this new correlation was validated using 200 L and 2000 L orbitally shaken bioreactors. In conclusion, the proposed correlation is a useful tool to predict the Power Input and hydrodynamics during cell cultivation in cylindrical shaken bioreactors of all scales.
Wolf Klöckner - One of the best experts on this subject based on the ideXlab platform.
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time efficient way to calculate oxygen transfer areas and Power Input in cylindrical disposable shaken bioreactors
Biotechnology Progress, 2014Co-Authors: Wolf Klöckner, Jochen Buchs, Sören Werner, Clemens Lattermann, Franz Pursche, Dieter EiblAbstract:Disposable orbitally shaken bioreactors are a promising alternative to stirred or wave agitated systems for mammalian and plant cell cultivation, because they provide a homogeneous and well-defined liquid distribution together with a simple and cost-efficient design. Cultivation conditions in the surface-aerated bioreactors are mainly affected by the size of the volumetric oxygen transfer area (a) and the volumetric Power Input (P∕VL) that both result from the liquid distribution during shaking. Since Computational Fluid Dynamics (CFD)—commonly applied to simulate the liquid distribution in such bioreactors—needs high computing Power, this technique is poorly suited to investigate the influence of many different operating conditions in various scales. Thus, the aim of this paper is to introduce a new mathematical model for calculating the values of a and P∕VL for liquids with water-like viscosities. The model equations were derived from the balance of centrifugal and gravitational forces exerted during shaking. A good agreement was found among calculated values for a and P∕VL, CFD simulation values and empirical results. The newly proposed model enables a time efficient way to calculate the oxygen transfer areas and Power Input for various shaking frequencies, filling volumes and shaking and reactor diameters. All these parameters can be calculated fast and with little computing Power. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1441–1456, 2014
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Power Input correlation to characterize the hydrodynamics of cylindrical orbitally shaken bioreactors
Biochemical Engineering Journal, 2012Co-Authors: Wolf Klöckner, Stéphanie Tissot, Florian M. Wurm, Jochen BuchsAbstract:Disposable cylindrical shaken bioreactors using plastic bags or vessels represent a promising alternative to stainless steel bioreactors, because they are flexible, cost-effective and can be pre-sterilized. Unlike conventional well-established steel bioreactors, however, such disposable bioreactor systems have not yet been precisely characterized. Thus, the aim of this current work is to introduce a new Power Input correlation as a potential means to characterize the hydrodynamics of these new systems. A set of rel- evant Power Input variables was defined and transformed into dimensionless numbers by using the Buckingham’s pi-Theorem. These numbers were then experimentally varied to quantify the relationship among the numbers. A simple correlation was generated for the Power Input with seven variables. The application of this new correlation was validated using 200 L and 2000 L orbitally shaken bioreactors. In conclusion, the proposed correlation is a useful tool to predict the Power Input and hydrodynamics during cell cultivation in cylindrical shaken bioreactors of all scales.
Helmuth Haak - One of the best experts on this subject based on the ideXlab platform.
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the influence of high resolution wind stress field on the Power Input to near inertial motions in the ocean
Geophysical Research Letters, 2013Co-Authors: Antonija Rimac, Jinsong Von Storch, Carsten Eden, Helmuth HaakAbstract:[1] The wind Power Input to near-inertial (NI) motions is studied using a global eddy-permitting ocean general circulation model. The model is forced by high- (1-hourly, at 0.35° resolution) and low-resolution (6-hourly, at 1.875° resolution) wind data. A change from low- to high-resolution forcing results in an increase in NI kinetic energy by a factor three and raises the wind-generated Power Input to NI motions from 0.3 TW to 1.1 TW. Time and space filtering of the wind fields yield less kinetic energy, with a larger drop from time filtering. This strong sensitivity to wind forcing points to a possible underestimation of the wind-generated energy available for deep ocean mixing in previous studies based on low-resolution winds.
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The influence of high‐resolution wind stress field on the Power Input to near‐inertial motions in the ocean
Geophysical Research Letters, 2013Co-Authors: Antonija Rimac, Carsten Eden, Jin-song Von Storch, Helmuth HaakAbstract:[1] The wind Power Input to near-inertial (NI) motions is studied using a global eddy-permitting ocean general circulation model. The model is forced by high- (1-hourly, at 0.35° resolution) and low-resolution (6-hourly, at 1.875° resolution) wind data. A change from low- to high-resolution forcing results in an increase in NI kinetic energy by a factor three and raises the wind-generated Power Input to NI motions from 0.3 TW to 1.1 TW. Time and space filtering of the wind fields yield less kinetic energy, with a larger drop from time filtering. This strong sensitivity to wind forcing points to a possible underestimation of the wind-generated energy available for deep ocean mixing in previous studies based on low-resolution winds.
Enrique Galindo - One of the best experts on this subject based on the ideXlab platform.
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Air and oil dispersions in a four-phase fermentation model, studied under varying physicochemical conditions and retrofitted constant gassed Power Input
Chemical Engineering Research & Design, 2017Co-Authors: Magdalena Brito-bazan, Diego Humberto Cuervo-amaya, Gabriel Corkidi, Enrique GalindoAbstract:Abstract In this study, experimental Power Input curves were obtained in a four-phase system. Sauter mean diameter of air and oil dispersions obtained in a four-phase Trichoderma harzianum fermentation model (aqueous salt solution, castor oil, air and T. harzianum mycelia) are presented. Experiments allowed to analyze the effect of varying amounts of surfactant (mixture of proteins coming from the biomass and bovine serum albumin) and solid concentration (mycelial biomass) on gassed Power Input, mean drop and bubble size distributions. Experimental Power Input measurements showed that the different mixtures of biomass and protein, keeping constant the agitation rate, affected the gassed Power consumption by approximately ±10%. By keeping the gassed Power Input fixed during the dispersion experiments, it was possible to rule out the effects of the Power consumption variation and to discern and analyze the impact of the amount of protein and biomass on the dispersion of air bubbles and oil drops. The protein, due to its surface-active properties, caused a considerable decrease in the Sauter mean diameter of air bubbles compared to the system without protein, regardless of the concentration. Protein did not have an effect on oil drops, which maintained a constant Sauter diameter through the studied concentration range (0–1.36 g/L). It was shown that, for comparable biomass concentrations, the gassed Power Input is the parameter determining the Sauter diameter of air bubbles as well as for the oil drops. It was found that, even by keeping the Power Input constant, the addition of biomass to the mixtures has additional interactions with the dispersions, decreasing the Sauter mean diameter of bubbles and increasing the value in oil drops.
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molecular weight and viscosifying Power of alginates produced in azotobacter vinelandii cultures in shake flasks under low Power Input
Journal of Chemical Technology & Biotechnology, 2016Co-Authors: Karen Gomezpazarin, Celia Flores, Tania Castillo, Enrique Galindo, Jochen Buchs, Carlos PenaAbstract:BACKGROUND The aim of this study was to evaluate the viscosifying Power and mean molecular weight (MMW) of alginate synthesized by Azotobacter vinelandii in a region of very low Power Input; as well as to scale-up the process of alginate production in a 3 L fermenter using the Power Input profile (determined in shake flasks) as criterion. RESULTS In cultures developed at very low Power Input (P/V) (0.02 to 0.68 kW m−3) and maximal oxygen transfer rate (OTRmax) from to 0.85 to 2.8 mmol L-1 h-1, both the specific growth rate and alginate production were negatively affected. In contrast, the viscosifying Power of the alginate increased significantly, with respect to that obtained at the highest Power Input (1.6 kW m−3). This behavior was related to the synthesis of alginates with a high MMW (2240 kDa). When profiles of Power Input determined in shake flasks at very low P/V were reproduced in a stirred fermentor, it was possible to reproduce the same trends in both the alginate production and the polymer viscosifying Power. CONCLUSION This study provides useful information in order to implement new scale-up strategies for alginate production, exhibiting chemical characteristics and viscosifying properties superior to commercial alginates. © 2015 Society of Chemical Industry
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Production of alginate by Azotobacter vinelandii in a stirred fermentor simulating the evolution of Power Input observed in shake flasks
Process Biochemistry, 2008Co-Authors: Carlos Pena, Modesto Millan, Enrique GalindoAbstract:By simulating the evolution of the actual Power Input observed in shake flasks it was possible to produce, in a fermentor, alginates having a very similar mean molecular mass (1700 kDa) to that obtained in the cultures developed in shake flasks (1800 kDa). Similar profiles of dissolved oxygen tension and oxygen transfer rate could be the reason.
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A New Pneumatic Bearing Dynamometer for Power Input Measurement in Stirred Tanks
Chemical Engineering & Technology, 1991Co-Authors: Roberto Reséndiz, Alfredo Martinez, Gabriel Ascanio, Enrique GalindoAbstract:A turntable dynamometer has been constructed for the accurate measurement of Power Input and mixing applications in bench stirred tank reactors. The main feature of this device is a pneumatic bearing with complementary conical parts. The conical pneumatic bearing permitted to apply eccentric loads without affecting its stability. The static friction torque in the pneumatic bearing was very small, 4 x Nm, and can be neglected in the experimental ranges of measured torques, i.e. from 5 x to 2.21 Nm. In accordance with the instrumentation used, the deviations obtained with the apparatus are less than 10% at low torque readings. At moderate torques, deviations lower than 1 % are routinely obtained. Several Power Input measurements show that the obtained data scatter is lower than 2.5 % . The Power Input response in the turbulent regime is in agreement with dimensional analysis: the Power Input depends on the cube of the impeller speed. In addition, data obtained with a turbine impeller under ungassed conditions agree with the predictions of a published correlation, which takes into account several geometrical parameters.
