Research Of A Novel CCERT System Based On Multiple-Electrode Excitation Strategy

Electrical resistance tomography(ERT)technique has the characteristics of simple structure,low cost,visualization and non-invasive.At present,it is one of the hotspots in the research field of electrical tomography technique.Combining ERT technique and capacitively coupled contactless conductivity detection(C4D),capacitively coupled electrical resistance tomography(CCERT)technique is proposed and it can realize contactless measurement.The CCERT technique can effectively avoid electrochemical corrosion and polarization caused by direct contact between sensor electrodes and measured liquid.Current CCERT systems are under single-electrode excitation strategy.In other research fields of electrical tomography technique,multi-electrode excitation strategy has been proved to be an effective method to improve the intensity of excitation signal and to increase the number of independent detection signals,and thus improve system performance.Therefore,the application of multi-electrode excitation strategy in CCERT system has broad industrial application prospects.It is necessary to study the performance of CCERT system under multi-electrode excitation strategy.In this dissertation,the CCERT system under multi-electrode excitation strategy is studied for the first time.An online CCERT system prototype under multi-electrode excitation strategy is successfully developed.With the developed prototype,data acquisition experiments are carried out and the performances of multi-electrode excitation strategy in image reconstruction and void fraction measurement are preliminarily studied.The main work and contribution of this dissertation are as follows:(1)The simulation study of CCERT sensor under multi-electrode excitation strategy is conducted,and its feasibility is verified.Then,the multi-electrode excitation strategy is applied to the CCERT system.Then,a CCERT system prototype under multi-electrode excitation strategy is developed,including the hardware circuit design,the upper/lower computer software programming and the online operation test.(2)The measurement performances of the CCERT system prototype are tested,including the data acquisition speed,data repeatability and image reconstruction result.The results show that,compared with the single-electrode excitation strategy,the data acquisition speed can meet the requirement of practical application,and the data repeatability and consistency are significantly improved.Among them,the two-electrode excitation strategy has better image reconstruction results,which lays a good foundation for the further study of the technology.(3)With the new developed CCERT system prototype,the void fraction measurement experiments are carried out.By using least square method,void fraction measurement is realized.The experimental results show that the multi-electrode excitation strategy has great advantages in the measurement of the void fraction of stratified flow.It has great potential for further development.