An adaptive electrical resistance tomography sensor with flow pattern recognition capability

The aim of this research is to use Electrical Resistance Tomography technique (ERT) to measure factors that affect local mass transfer at various axial locations in a random packed column with diameter 0.3m and bed height 150cm filled with 2 cm plastic spheres. These factors are: liquid maldistribution, velocity profiles, and flow pattern. The system was designed to run in a trickling down-flow mode and a full liquid up-flow mode. Experiments were performed at flow rates of 3, 6, and 9 gpm (or 0.27 x 10⁻², 0.54 x 10⁻² and 0.8 x 10⁻² m³/m² s) and under normal operating conditions of 25C° and atmospheric pressure. The liquid maldistribution factors were measured via ERT technique and the conventional liquid collection method. Both measurements were conducted at various fluid flow rates at different bed heights. The results of ERT were in very good agreement with the conventional method. The standard deviation values were 17% and 21% at flow rates 3 and 6 gpm respectively. The numerical values of velocity for full liquid up flow at 3 gpm were 0.83cm/s, 1.2cm/s, 1.2 cm/s and 1.11 cm/s for different heights of 30, 60 and 90 cm respectively and the numerical values of velocity for trickle down flow at 3 gpm were 16.5 cm/s, 22.5 cm/s and 24 cm/ for different heights of 30, 60 and 90 cm respectively. The values of the liquid maldistribution factor for flow rate 3 gpm were 0.43 (30cm), 0.33(60cm) and 0.30 (90cm) and for flow rate 6 gpm were 0.33(30cm), 0.27(60cm) and 0.22 (90cm). By comparison with findings of many studies conducted on liquid distribution in packed bed column, a good agreement was observed on the relation of Mf and flow rates and bed heights.

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Using electrical resistance tomography (ERT) and computational fluid dynamics (CFD) to study the mixing of pseudoplastic fluids with a SCABA 6SRGT impeller

10.32920/ryerson.14645163 ◽

2021 ◽

Author(s):

Leila Pakzad

Keyword(s):

Flow Field ◽

Flow Pattern ◽

Electrical Resistance ◽

Mixing Time ◽

Three Dimensions ◽

Cfd Modeling ◽

Cube Root ◽

Mixing Times ◽

Electrical Resistance Tomography ◽

Good Agreement

The objective of this work is to use electrical resistance tomography (ERT) and computational fluid dynamic (CFD) modeling to investigate the flow field generated by a Scaba 6SRGT impeller in the agitation of the xanthan solution, as a pseudoplastic fluid with yield stress. ERT provides a non-destructive technique to measure, in three dimensions, the concentration fields inside the mixing tanks. Using ERT, the impeller flow pattern, the dimensions of the cavern formed and the mixing time in the agitation of xanthan solutions were evaluated. The sizes of cavern measured using ERT were in good agreement with that calculated using Elson's model (cylindrical model). ERT provides both overall mixing time using 1264 probes (316 probes for each plan) and local mixing time using 4 selected probes or pixels. The dimensionless mixing times obtained from ERT were correlated well with the Moo-Young correlation, confirming that increased impeller speeds decreases the mixing times. The 3D flow field generated by a Scaba 6SRGT impeller and tracer homogenization in the agitation of xanthan gum were also simulated using the commercial CFD package (FLUENT). The experimental torque measurements were used to validate the numerical simulations. The validated CFD model provided useful information regarding the impeller pumping capacity and flow pattern, the velocity profiles, the formation of cavern around the impeller, and the mixing time. CFD results show good qualitative as well as quantitative agreement with the experimental results and theory. The sizes of cavern measure using CFD were in good agreement with that calculated using Elson's model. The local mixing times predicted from CFD simulations agreed well with literature in a way that mixing times varied inversely with the cube root of the power consumed per unit volume of the solution. CFD under predicted the local mixing times measured using ERT by 11-47%.

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Visualisation of flow pattern and measurement of liquid distribution in a random packed column using electrical resistance tomography (ERT)

10.32920/ryerson.14651730 ◽

2021 ◽

Author(s):

Nazar Aoda

Keyword(s):

Flow Pattern ◽

Flow Rate ◽

Electrical Resistance ◽

Packed Column ◽

Operating Conditions ◽

Flow Mode ◽

Electrical Resistance Tomography ◽

Liquid Distribution ◽

Flow Rates ◽

Good Agreement

The aim of this research is to use Electrical Resistance Tomography technique (ERT) to measure factors that affect local mass transfer at various axial locations in a random packed column with diameter 0.3m and bed height 150cm filled with 2 cm plastic spheres. These factors are: liquid maldistribution, velocity profiles, and flow pattern. The system was designed to run in a trickling down-flow mode and a full liquid up-flow mode. Experiments were performed at flow rates of 3, 6, and 9 gpm (or 0.27 x 10⁻², 0.54 x 10⁻² and 0.8 x 10⁻² m³/m² s) and under normal operating conditions of 25C° and atmospheric pressure. The liquid maldistribution factors were measured via ERT technique and the conventional liquid collection method. Both measurements were conducted at various fluid flow rates at different bed heights. The results of ERT were in very good agreement with the conventional method. The standard deviation values were 17% and 21% at flow rates 3 and 6 gpm respectively. The numerical values of velocity for full liquid up flow at 3 gpm were 0.83cm/s, 1.2cm/s, 1.2 cm/s and 1.11 cm/s for different heights of 30, 60 and 90 cm respectively and the numerical values of velocity for trickle down flow at 3 gpm were 16.5 cm/s, 22.5 cm/s and 24 cm/ for different heights of 30, 60 and 90 cm respectively. The values of the liquid maldistribution factor for flow rate 3 gpm were 0.43 (30cm), 0.33(60cm) and 0.30 (90cm) and for flow rate 6 gpm were 0.33(30cm), 0.27(60cm) and 0.22 (90cm). By comparison with findings of many studies conducted on liquid distribution in packed bed column, a good agreement was observed on the relation of Mf and flow rates and bed heights.

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A Novel PCA-GRNN Flow Pattern Identification Algorithm for Electrical Resistance Tomography System

Advances in Intelligent and Soft Computing - Advances in Computer Science and Information Engineering ◽

10.1007/978-3-642-30126-1_40 ◽

2012 ◽

pp. 249-254

Author(s):

Yanjun Zhang ◽

Yu Chen

Keyword(s):

Flow Pattern ◽

Electrical Resistance ◽

Pattern Identification ◽

Identification Algorithm ◽

Electrical Resistance Tomography ◽

Tomography System ◽

Flow Pattern Identification

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Using electrical resistance tomography (ERT) and computational fluid dynamics (CFD) to study the mixing of pseudoplastic fluids with a SCABA 6SRGT impeller

10.32920/ryerson.14645163.v1 ◽

2021 ◽

Author(s):

Leila Pakzad

Keyword(s):

Flow Field ◽

Flow Pattern ◽

Electrical Resistance ◽

Mixing Time ◽

Three Dimensions ◽

Cfd Modeling ◽

Cube Root ◽

Mixing Times ◽

Electrical Resistance Tomography ◽

Good Agreement

The objective of this work is to use electrical resistance tomography (ERT) and computational fluid dynamic (CFD) modeling to investigate the flow field generated by a Scaba 6SRGT impeller in the agitation of the xanthan solution, as a pseudoplastic fluid with yield stress. ERT provides a non-destructive technique to measure, in three dimensions, the concentration fields inside the mixing tanks. Using ERT, the impeller flow pattern, the dimensions of the cavern formed and the mixing time in the agitation of xanthan solutions were evaluated. The sizes of cavern measured using ERT were in good agreement with that calculated using Elson's model (cylindrical model). ERT provides both overall mixing time using 1264 probes (316 probes for each plan) and local mixing time using 4 selected probes or pixels. The dimensionless mixing times obtained from ERT were correlated well with the Moo-Young correlation, confirming that increased impeller speeds decreases the mixing times. The 3D flow field generated by a Scaba 6SRGT impeller and tracer homogenization in the agitation of xanthan gum were also simulated using the commercial CFD package (FLUENT). The experimental torque measurements were used to validate the numerical simulations. The validated CFD model provided useful information regarding the impeller pumping capacity and flow pattern, the velocity profiles, the formation of cavern around the impeller, and the mixing time. CFD results show good qualitative as well as quantitative agreement with the experimental results and theory. The sizes of cavern measure using CFD were in good agreement with that calculated using Elson's model. The local mixing times predicted from CFD simulations agreed well with literature in a way that mixing times varied inversely with the cube root of the power consumed per unit volume of the solution. CFD under predicted the local mixing times measured using ERT by 11-47%.

Download Full-text