Development Of A New Capacitively Coupled Electrical Resistance Tomography System

As one of the most important electrical tomography technologies, electrical resistance tomography(ERT) technique has the advantages of simple construction, low cost, high speed and non-invasion, etc. Combining capacitively coupled contactless conductivity detection (C4D) technique and traditional ERT technique, Capacitively Coupled ERT(CCERT) can implement contactless measurement, which would avoid electrode polarization effect and electrochemical erosion caused by the direct contact between the electrodes and liquid. The new CCERT can expand the application of ERT in industry. However, since current CCERT system adopted analog phase-sensitive demodulation technique to measure the resistance, high measuring accuracy and data acquisition speed is limited in the existing system.To solve the problems mentioned above, digital phase-sensitive demodulation technique is applied to the design of new CCERT system and the system prototype shows better performance. Meanwhile, the CCERT prototype is used to carry out research on dynamic image reconstruction of air-water two-phase flow.The main works and innovations of this dissertation are listed as follows:(1) Based on the digital phase-sensitive demodulation technique, a new CCERT prototype is developed. The prototype can operate online and acquire the images of the conductivity distribution.(2) The performance of the new developed prototype is tested including data acquisition speed, measuring accuracy and image reconstruction quality. Experiment results indicate that compared with CCERT system based on analog phase-sensitive demodulation technique, the new system achieves enhancement in performance, which lays the groundwork for further research on the CCERT technique.(3) To verify the feasibility of dynamic image reconstruction of air-water two-phase flow using the developed CCERT prototype, a new CCERT sensor is designed. Experiments of static image reconstruction are first carried out to test the effectiveness and performance of the new sensor. And then an experimental device for dynamic image reconstruction is constructed. Dynamic experiment results show that CCERT system can successfully acquire the real-time image of air-water two-phase flow.