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Toward Imaging of Multiphase Flows using Electrical Capacitance Tomography

Rasel, Rafiul Karim
http://orcid.org/0000-0002-2850-8493
http://rave.ohiolink.edu/etdc/view?acc_num=osu155715027714914

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Electrical capacitance tomography (ECT) is a widely used tomographic modality to image multiphase flows in the chemical and oil industry. Due to some distinct advantages, NASA and Department of Energy (DoE) also have a particular interest in ECT-based imaging technology. The image reconstruction problem in ECT is inherently non-linear, and imaging of multiphase flows holding water as continuous phase (i.e., water-dominated flows) is especially challenging for conventional ECT due to the high permittivity of water. In this dissertation, we introduce a new approach based on the multi-frequency excitation of ECT sensors for real-time monitoring of multiphase flows holding water as either the continuous phase or the dispersed phase. The proposed approach exploits the dielectric dispersion due to interfacial polarization commonly known as the Maxwell-Wagner-Sillars (MWS) effect, which is present in multiphase flows with at least one conducting phase. For water continuous multiphase flows, MWS-ECT enables us to image and continuously monitor the flow in the region of interest. We then implement an MWS-ECT-based imaging technique to decompose and continuously monitor multiphase flow mixture components (fractional areas or volumes) in mixtures containing dispersed conducting phases. Besides MWS-ECT, Displacement-Current Phase Tomography (DCPT) is another imaging modality to image multiphase flows containing water. DCPT is a relatively new imaging technique that can provide superior imaging quality if water is present. DCPT uses the same hardware and reconstruction technique as ECT and inherits almost all of its hardware and software advantages. In this work, we introduce a novel technique based on the MWS effect to improve the performance of DCPT applied to two-phase flow imaging. Moreover, due to recent developments in electrical capacitance volume tomography (ECVT), direct extraction of the volumetric images from the measured data is now possible. Unlike conventional (2D) ECT, ECVT extracts volumetric information needed for industrial flow optimization. However, compared to ECT, the high correlation between measurements in ECVT exacerbates the ill-conditioning of the associated imaging problem. Previous studies have shown that the mutual capacitance data between ECVT electrodes located at cross-planes that are well separated along the sensor axis can be neglected without significantly affecting the imaging resolution. In this dissertation, we examine in detail and quantify the effect of reduced cross-plane acquisition strategies for optimizing image reconstruction and constraining the ill-conditioning of typical ECVT settings. The primary contribution of this dissertation relies on the multi-frequency excitation of ECT/DCPT sensors to exploit MWS effect to improve imaging results.
Fernando Teixeira, Prof. (Advisor)
Robert Burkholder, Prof. (Committee Member)
Kubilay Sertel, Prof. (Committee Member)
137 p.
Electrical Engineering
Electrical Capacitance Tomography, Multifrequency Excitation, Maxwell-Wagner-Sillars, Flow Decomposition, Displacement Current Phase Tomography

Recommended Citations

Citations

  • Rasel, R. K. (2019). Toward Imaging of Multiphase Flows using Electrical Capacitance Tomography [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu155715027714914

    APA Style (7th edition)

  • Rasel, Rafiul. Toward Imaging of Multiphase Flows using Electrical Capacitance Tomography. 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu155715027714914.

    MLA Style (8th edition)

  • Rasel, Rafiul. "Toward Imaging of Multiphase Flows using Electrical Capacitance Tomography." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu155715027714914

    Chicago Manual of Style (17th edition)

osu155715027714914
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This open access ETD is published by The Ohio State University and OhioLINK.