Research On The Exciting-measuring Mode For Electrical Capacitance Tomography System Based On COMSOL

In ECT, an array of electrodes is attached around the object and alternating voltages are injected via these electrodes and the resulting capacitance values are measured. Using the measurements on the boundary, an approximation for the spatial distribution of capacitance within the object can be reconstructed. ECT has wide applications in industrial fields for the advantages of non-intrusive, being fast in response and capable of acquiring 2D/3D image information of distribution parameter.In this paper, 2D/3D ECT models are established and analyzed by the COMSOL simulation software, which can be modeled flexibly and solved accurately. The main work and conclusions are as follows:(1) Two normalized sensitivity matrix modes are studied. The results show that the normalized sensitivity matrix can improve the sensitivity distribution uniformity and improve the quality of the image reconstruction.(2) For the 2D ECT system, this paper presented one kind of new exciting-measuring mode for ECT sensor consisting of 24 segments linked in eight groups, treated as single, extremely broad electrodes forming 8-electrode sensor. The values and the dynamic range of measured capacitance data, the uniformity of sensitivity distribution and the reconstructed images of different flow regimes were compared with the conventional 12-electrode sensor. The presented exciting-measuring mode will not cause the decrease of real-time reconstruction speed, and will reduce the difficulty of measurement circuit. Meanwhile, the sensitivity distribution is more uniform and the quality of reconstructed images for the objects in the central locations is improved obviously.(3) For the 3D ECT system, compared with single-layer ECT system, three-layer ECT system can improve the quality of the image reconstruction. Two kinds of new exciting-measuring mode for three-layer ECT sensor are proposed, which need not to increase much more hardware costs and improve the quality of the reconstruction image.Take the imaging index into account, the longitudinal rectangle mode is the better method.