Establishment of a simple method to evaluate mixing times in a plastic bag photobioreactor using image processing based on freeware tools

2021 ◽  
Author(s):  
Michael Sandmann
Keyword(s):  
Image Processing ◽  
Optical Method ◽  
Gas Flow ◽  
Mixing Time ◽  
Pearson Correlation ◽  
Mixing Times ◽  
Simple Method ◽  
Area Of Interest ◽  
Background Removal ◽  
Programming Skills

Abstract Objective The aim of this work was to develop a simple optical method to determine the mixing time in a photobioreactor. The image processing method should be based on freeware tools and should not require programming skills. Results An optical method has been established to analyze images from recorded videos of mixing experiments. The basic steps are: 1. Extraction of a sequence of images from the video file; 2. Cropping of the pictures; 3. Background removal; and 4. Image analysis and mixing time evaluation based on quantification of pixel-to-pixel heterogeneity (standard deviation over pixel intensities) within a given area of interest. The novel method was generally able to track the dependency between aeration rate and mixing time within the investigated photobioreactor. In a direct comparison, a Pearson correlation coefficient of rho = 0.9957 was obtained. Gas flow rates between 10 L h−1, and 300 L h−1 resulted from mixing times of between 48 sec and 14 sec, respectively. This simple technique is applicable even without programming skills and can be used in education within high schools and in early stages of undergraduate programs.

scholarly journals Establishment of a simple method to evaluate mixing times in a plastic bag photobioreactor using image processing based on freeware tools

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Henrike Wurm ◽  
Michael Sandmann
Keyword(s):  
Image Processing ◽  
Optical Method ◽  
Gas Flow ◽  
Mixing Time ◽  
Accurate Determination ◽  
Mixing Times ◽  
Simple Method ◽  
Area Of Interest ◽  
Background Removal ◽  
Programming Skills

Abstract Objective Accurate determination of the mixing time in bioreactors is essential for the optimization of the productivity of bioprocesses. The aim of this work was to develop a simple optical method to determine the mixing time in a photobioreactor. The image processing method should be based on freeware tools, should not require programming skills, and thus could be used in education within high schools and in early stages of undergraduate programs. Results An optical method has been established to analyze images from recorded videos of mixing experiments. The steps are: 1. Extraction of a sequence of images from the video file; 2. Cropping of the pictures; 3. Background removal; and 4. Image analysis and mixing time evaluation based on quantification of pixel-to-pixel heterogeneity within a given area of interest. The novel method was generally able to track the dependency between aeration rate and mixing time within the investigated photobioreactor. In direct comparison, a pearson correlation coefficient of rho = 0.99 was obtained. Gas flow rates between 10 L h−1, and 300 L h−1 resulted from mixing times of between 48 and 14 s, respectively. This technique is applicable without programming skills and can be used in education with inexperienced user groups.

Mixing Design for Air Agitated Rectangular Tanks

1980 ◽  
Vol 15 (1) ◽  
pp. 1-16
Author(s):  
W. Akhtar ◽  
G.P. Mathur ◽  
D.S. Dickey
Keyword(s):  
Convective Flow ◽  
Large Scale ◽  
Gas Flow ◽  
Liquid Velocity ◽  
Mixing Time ◽  
Waste Water Treatment ◽  
Operating Conditions ◽  
Turbulent Dispersion ◽  
Mixing Times ◽  
Tank Geometry

Abstract Design equations have been developed to estimate liquid velocities and mixing times in air agitated tanks. Determination of the gas rate necessary for adequate agitation in a given geometry is possible with this information. Air agitation offers benefits of increased dissolved oxygen and cost effective mixing for some waste water treatment applications. Empirical expressions for surface and bottom velocities, as a function of gas flow rate and tank geometry have been developed from laboratory measurements. Since neither statistical nor dimensional analysis of the laboratory results could prove conclusively the correct form of the velocity correlations, the different correlation forms were used to verify large scale velocity measurements. Only one of the three trial correlations correctly predicted large scale velocities. The importance of these velocity correlations is evident from experience with mechanical agitator design, which shows that liquid velocity is the appropriate design criterion for most similar applications. Mixing times were measured experimentally in the laboratory and studied with a mathematical model. The model was an unsteady state mass balance containing convective flow terms with turbulent dispersion super-imposed on the flow. The velocities for the convective flow terms were calculated from the empirical velocity correlations. Estimates of the turbulent dispersion coefficients were investigated experimentally. Because multiple velocity correlations and a computer model for mixing time are difficult to use when performing design calculations, empirical correlations for bulk velocity and mixing time were derived. Combined with a relationship for power input, the design correlations provide information necessary to determine operating conditions in large scale, air agitated tanks. The effects of tank geometry on air agitated design have been explored within a range of typical construction dimensions. Thus, the principal elements of a complete design approach to air agitated rectangular tanks are presented.

scholarly journals Study of the Effect of a Plug with Torsion Channels on the Mixing Time in a Continuous Casting Ladle Water Model

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1942
Author(s):  
Gerardo Aguilar ◽  
Gildardo Solorio-Diaz ◽  
Alicia Aguilar-Corona ◽  
José Angel Ramos-Banderas ◽  
Constantin A. Hernández ◽  
...  
Keyword(s):  
Continuous Casting ◽  
Mixing Time ◽  
Tangential Velocity ◽  
Water Model ◽  
Mixing Times ◽  
Low Velocity ◽  
Velocity Magnitude ◽  
Image Velocimetry ◽  
Casting Ladle ◽  
Upward Direction

The use of porous plugs in injecting gas through the bottom of a ladle forms vertical plumes in a very similar way to a truncated cone. The gas plume when exiting the plug has a smaller diameter compared to that formed in the upper zone of the ladle because inertial forces predominate over buoyancy forces in this zone. In addition, the magnitude of the plume velocity is concentrated in an upward direction, which increases the likelihood of low velocity zones forming near the bottom of the ladle, especially in lower corners. In this work, a plug with spiral-shaped channels with different torsion angles is proposed, with the objective that the gas, when passing through them, has a tangential velocity gain or that the velocity magnitude is distributed in the three axes and does not just focus on the upward direction, helping to decrease low velocity zones near the bottom of the ladle for better mixing times. For the experimentation, we worked in a continuous casting ladle water model with two configuration injections, which in previous works were reported as the most efficient in mixing the steel in this ladle. The results obtained using the PIV technique (particle image velocimetry) and conductimetry technique indicate that the plugs with the torsion channels at angles of 60° and 120° improve the mixing times for the two injection configurations.

scholarly journals Retrieval of similar topographic areas.

2016 ◽  
Vol 47 (1) ◽  
pp. 275
Author(s):  
E. Kokinou ◽  
C. Panagiotakis ◽  
Th. Kinigopoulos
Keyword(s):  
Image Processing ◽  
High Efficiency ◽  
Automatic Extraction ◽  
Local Minima ◽  
Initial Model ◽  
Area Of Interest ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data ◽  
Step Number

Image processing and understanding and further pattern recognition comprises a precious tool for the automatic extraction of information using digital topography. The aim of this work is the retrieval of areas with similar topography using digital elevation data. It can be applied to geomorphology, forestry, regional and urban planning, and many other applications for analyzing and managing natural resources. In specifics, the user selects the area of interest, navigating overhead a high resolution elevation image and determines two (3) parameters (step, number of local minima and display scale). Furthermore the regions with similar relief to the initial model are determined. Experimental results show high efficiency of the proposed scheme.

scholarly journals Optimization of the Mixing Time Using Asymmetrical Arrays in Both Gas Flow and Injection Positions in a Dual-plug Ladle

2020 ◽  
Vol 60 (6) ◽  
pp. 1172-1178 ◽  
Author(s):  
José de Jesús Villela-Aguilar ◽  
José Ángel Ramos-Banderas ◽  
Constantin Alberto Hernández-Bocanegra ◽  
Antonio Urióstegui-Hernández ◽  
Gildardo Solorio-Díaz
Keyword(s):  
Gas Flow ◽  
Mixing Time

Modeling and Optimizing of Mechanically Agitated Vessels by Central Composite Rotatable Design Method

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Ramin Zadghaffari ◽  
Jafarsadegh Moghaddas ◽  
F. Fakheri ◽  
H. Razmi ◽  
H. Heidari
Keyword(s):  
Gas Flow ◽  
Design Method ◽  
Mixing Time ◽  
Central Composite Rotatable Design ◽  
Two Phase ◽  
Injection Point ◽  
Tracer Injection ◽  
Operating Variables ◽  
Central Composite ◽  
Rotatable Design

A central composite rotatable design (CCRD) methodology was used to analyze the effect of some operating variables on gas-liquid two phase mixing time in an agitated tank driven by dual 6-blade Rushton turbines. The variables chosen were the impellers rotational speed (x1), gas flow rate (x2), probe location (x3) and tracer injection point (x4). The mathematical relationship of mixing time on the four significant independent variables can be approximated by a nonlinear polynomial model. Predicted values were found to be in good agreement with the experimental values (R-sq of 95.9 percent and R-Sq (Adj) of 95.7 percent for response Y). This study has shown that central composite design could efficiently be applied for the modeling of mixing time, and it is an economical way of obtaining the maximum amount of information with the fewest number of experiments.

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