A study on optimum electrical capacitance tomography data for intelligent system recognition of flow regime

2008 ◽  
Author(s):  
Khursiah Zainal-Mokhtar ◽  
Junita Mohamad-Saleh
Keyword(s):  
Flow Regime ◽  
Intelligent System ◽  
Electrical Capacitance Tomography ◽  
Electrical Capacitance ◽  
Capacitance Tomography ◽  
Tomography Data

Horizontal Two Phase Flow Regime Identification: Comparison of Pressure Signature, Electrical Capacitance Tomography (ECT) and High Speed Visualization

2012 ◽  
Author(s):  
Paul J. Kreitzer ◽  
Michael Hanchak ◽  
Larry Byrd
Keyword(s):  
Flow Regime ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Regimes ◽  
Electrical Capacitance Tomography ◽  
Phase Flow ◽  
Electrical Capacitance ◽  
Flow Conditions ◽  
Two Phase ◽  
Capacitance Tomography

Understanding the behavior of transient two phase refrigerant flow is an important aspect of implementing vapor compression systems in future aerospace applications. Pressure drop and heat transfer coefficient are important parameters that guide the design process, and are influenced by flow regime. Published two phase flow models rely heavily on a priori knowledge of the current two phase flow conditions including flow regime. Additional complications arise when applying published correlations to a range of systems because each correlation is based on a specific set of experimental conditions, including working fluid, flow orientation, channel size, and channel shape. Non-intrusive measurement techniques provide important advantages while measuring the behavior of two phase flow systems. A two phase flow experimental test rig has been developed at the Air Force Research Laboratory, providing a closed loop refrigeration system capable of producing flow regimes from bubbly through annular flow. Two phase flow is produced by pumping subcooled R134a through a heat exchanger with 40 minichannels into an adiabatic transparent fused quartz observation channel with a hydraulic diameter of 7 mm. Refrigerant mass flux is varied from 100–400 kg/m2s with a heat flux from 0–15.5 W/cm2. Temperatures ranged from 18–25 °C and pressures between 550–750 kPa. The data from high speed pressure transducers were analyzed using standard signal processing techniques to identify the different flow regimes. Initial results indicate that different flow regimes can be identified from their pressure signature. In addition, real-time void fraction measurements were taken using Electrical Capacitance Tomography (ECT). This paper describes the process behind ECT systems used to measure two phase flow conditions. Comparisons with high speed video assess the accuracy of ECT measurements in identifying various two phase flow conditions. Results indicate variations between ECT and high speed images, however, enough information is provided to create flow pattern maps and regime identification for different superficial vapor and liquid velocities.

scholarly journals Control of pellets coating in a Wurster fluidised bed by means of electrical capacitance tomography

2019 ◽  
Vol 42 (4) ◽  
pp. 729-742
Author(s):  
Hanqiao Che ◽  
Haigang Wang ◽  
Jiamin Ye ◽  
Wuqiang Yang
Keyword(s):  
Flow Regime ◽  
Volume Fraction ◽  
Electrical Capacitance Tomography ◽  
Fluidised Bed ◽  
Electrical Capacitance ◽  
Cross Sectional ◽  
Local Flow ◽  
Whole Process ◽  
Flow Information ◽  
Capacitance Tomography

Wurster fluidised bed is commonly used for coating pellets in the pharmaceutical industry. Normally, the control in a Wurster fluidised bed for coating is based on point-based measurement, that is, pressure and optical probes. However, the point-based measurement methods only provide local flow information and cannot reveal the cross-sectional flow dynamics characteristics and it is difficult to control the whole process with limited data. In this paper, electrical capacitance tomography (ECT) is applied to reconstruct the solids distribution in a lab-scale Wurster fluidised bed for coating pellets and the measurements are used in a control loop of the process. The flow regime is identified from the ECT images using a simple but efficient approach. The objective of control is to keep stable minimum fluidisation and avoid undesired flow regime in the region between the outside wall and the Wurster tube, such as intermittent, plug and defluidisation. To achieve this target, a PID controller is applied to keep a low volume fraction in the annular region by adjusting the fluidisation air rate, and bang-bang control is applied to a peristaltic pump used for spraying coating solutions based on the detected flow regime. It has been found that the proposed control scheme based on the ECT measurement is effective for keeping a stable flow regime, reducing the degree of pellets agglomeration and avoiding defluidisation.

DESIGN OF FLEXIBLE ELECTRICAL CAPACITANCE TOMOGRAPHY SENSOR

2015 ◽  
Vol 77 (28) ◽  
Author(s):  
MT Masturah ◽  
MHF Rahiman ◽  
Zulkarnay Zakaria ◽  
AR Rahim ◽  
NM Ayob
Keyword(s):  
Outer Layer ◽  
Electrical Capacitance Tomography ◽  
Electrical Capacitance ◽  
Capacitance Tomography ◽  
Fluid Imaging

This paper discussed the design–functionality and application of Flexible Electrical Capacitance Tomography sensor (FlexiECT). The sensors consist of 12 electrodes allocated surrounding the outer layer of the pipeline. The sensor is designed in such that the flexibility features suit the applications in the pipeline of multiple size. This paper also discussed the preliminary result of FlexiECT applications in fluid imaging by identifying the percentage of two mixing fluids.

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