Simulation study on electrical resistance tomography using metal wall for bubble detection

Industrial process pipelines are mostly known to be constructed from metal which is a conducting material. Bubbles or gas detection are crucial in facilitating the bubble columns performance. By employing the Electrical Resistance Tomography (ERT) technique, a simulation study using COMSOL has been conducted to investigate the effect of excitation strategy, bubble sizes and locations towards the metal wall system. As for the current excitation strategy, conducting boundary protocol has to be applied when it comes to metallic vessel to overcome the grounding effect. Bubbles with a greater size than 2 mm and especially the one that is located near the wall boundary are much easier to detect. Further potential improvements to the current design and image reconstruction of the ERT system are desirable to improve the detection of small and centred bubble

Forward problem solving for non-invasive electrical resistance tomography system

This paper aims to provide a forward problem solving for non-invasive electrical resistance tomography. A finite element model (FEM) using COMSOL Multiphysics is implemented for generating the sensitivity map for ERT system. Later, a masking data for a better sensitivity map was done to optimize the map. As a result, the sensitivity map can be used later for reconstructing the image of the medium of interest

The experimental study and numerical simulation of falling liquid film flow on horizontal tubes

This research is motivated by two observations: No report has been found so far in studies of water falling film up to 100 mm intertube spacing. No simulation analysis of film thickness under influence of intertube spacing in 3 dimensional models. Therefore, to the best of author’s knowledge, this research aims to illuminate the effects of intertube spacing between horizontal tubes on water falling film. An experimental investigation of water falling film temperature was conducted to explore the characteristics of heat transfer coefficients. In this study, the intertube spacing from smallest size of 8 mm and up to 100 mm were analyzed for Reynolds number range of 300 to 3300. The experimental data was extracted from calibrated test rig and the effect is investigated using numerical study. On the other hand, the effect of film thickness is numerically investigated for intertube spacing range of 10 mm to 40 mm. The numerical simulation was presented using the Volume of Fluid (VOF) technique where it is capable in determining temperatures and thickness of water falling film under influence of ambient factors. The experimental results reveal that intertube spacing of 133 mm produced the maximum heat transfer coefficient of 6 kW/m² K with percentage of error below 7%. The results of the numerical simulation indicate that the 40 mm intertube spacing presented the minimal average film thickness of 0.3 mm within ± 50% errors. Implications of the results and future research directions are also presented

Study and design of an ultrasonic flow tomographic front-end multi level measurement system

With the rapid evolution of electro-acoustical technology, ultrasonic tomography has made considerable progress in industry. An ultrasonic tomography system provides non-invasive and non-intrusive flow visualisation that enhances the understanding of fluid flow processes. The function of ultrasonic tomography is to continuously monitor the dynamics of liquid flow without interrupting the flow. The ultrasonic tomography technique is fully supported by a front-end hardware system. The front end is defined as all the hardware circuitries, including the ultrasonic transducer up to the Analogue-to-Digital Convertors (ADCs), even though the primary focus is the analogue signal processing components. We present here the challenges and trade-offs in the implementation of a front-end system by first explaining the basic operation of such a system, and then indicating what particular performance parameters are needed to ensure optimal system operation. Based on the results from our research studies, we propose an improved front-end multi-level solution that is more accurate than previous solutions and provides real-time measurement capability

Image Reconstruction for Solid Profile Measurement in ERT using Non-invasive Approach

Image reconstruction software and its image reconstruction algorithm are an important step towards constructing a tomography system. This paper demonstrates an image reconstruction of solid profile using linear back projection (LBP) algorithm and global threshold. A forward problem and inverse problem are discussed. The modelled of sensitivity distributions using COMSOL proved that the system is able to detect the liquid-solid regime in vertical pipe. Additionally, the location of the phantom can be easily distinguished using LBP algorithm and thresholding technique. The simulations and experiments results indicate that the sensitivity distribution of non-invasive ERT system can be applied in getting a tomogram of the medium of interest

Development of electrical resistance tomography applying vertical metallic column

Majority of industrial pipelines and process vessels are constructed from conducting composites. This paper focusing on the hardware and software development of laboratory test Electrical Resistance Tomography (ERT) measurement methods to obtain the cross-sectional image of the conductivity distribution of gas bubble phantom in a static vertical metallic column filled with water. The system with sixteen sensors implementation was investigated on a stainless steel vertical column of 100 mm inner diameter. The conducting boundary strategy was applied as the measurement strategy. Software for the current study was developed using Graphical User Interface (GUI) application program in MATLAB. The software contains many functions to ease user to get necessary information from the research done. The cross section image of the bubble phantom was reconstructed using Linear Back Projection (LBP) algorithm after the data collection process was completed. The system has been tested and can successfully generate the phantom under test

Simulation of frequency selection for invasive approach of electrical capacitance tomography for conducting pipe application using oil-gas regimes

Electrical capacitance tomography (ECT) is a common imaging technique in process tomography that has been used in various applications especially in pipe applications. It works by measuring the dielectric permittivity distribution in the interior of pipe using capacitive sensors. Based on the principle of ECT, signals are generated from transmitter and delivered to the right receiver using certain frequency. Assuming random selection of frequency could affect the wanted signal at the receivers, this paper will analyse the frequency selection ranged from 100 to 500 kHz with increment of 50 kHz thoroughly. The objective of this paper is to select the right frequency for the invasive approach of ECT for the conducting pipe applications using common parameter in ECT and oil-gas regimes as a medium. The frequency selection is observed using the voltage reading at each of the receivers and simulated using COMSOL Multiphysics software. Based on the results, the optimal frequency selection is 400 kHz where the best coverage area of sensor is 90%. This selection has the highest value of electrical voltage among other range proposed while the least electrical voltage produce is at frequency 300 kHz and coverage area of 50%

An Overview of Electrical Characterization Techniques for Biological Cell

In this paper, various electrical characterization techniques available for biological cell have been systematically reviewed. It covers both invasive and non-invasive approaches for population and single cell based studies. Examples of invasive technique consist of probing and patch clamp that measures the ionic current. However, depending on the applications, the non-invasive techniques are far more superior and popular. Some of the technique such as dielectric spectroscopy, electrorotation and dielectrophoresis measures the cell conductivity and dielectric constant. Furthermore, previous researchers proved that non-invasive technique may reduce the harmful effect on the cell due to electrical exposure. The review compares in terms of working principles, sample applications, advantages and limitations of each technique.&nbsp

Fundamental Sensor Development in Electrical Resistance Tomography

This paper will provide a fundamental understanding of one of the most commonly used tomography, Electrical Resistance Tomography (ERT). Unlike the other tomography systems, ERT displayed conductivity distribution in the Region of Interest (ROI) and commonly associated to Sensitivity Theorem in their image reconstruction. The fundamental construction of ERT includes a sensor array spaced equally around the imaged object periphery, a Data Acquisition (DAQ), image reconstruction and display system. Four ERT data collection strategies that will be discussed are Adjacent Strategy, Opposite Strategy, Diagonal Strategy and Conducting Boundary Strategy. We will also explain briefly on some of the possible Data Acquisition System (DAQ), forward and inverse problems, different arrangements for conducting and non-conducting pipes and factors that influence sensor arrays selections