Abstract
This paper describes an electrical capacitance tomography (ECT) system for imaging of two-phase flows. The capacitance sensor was built with eight electrodes around an insulating pipe. In the proposed capacitance measurement system, when an electrode is an emitter, the seven other electrodes are receivers, leading to a parallel reading tomography type. For a 8-electrode sensor, there are 28 independent readings. In order to improve the measurement system time response, a new electronic transducer was developed that supports excitation frequency up to 16 MHz. The proposed ECT system was tested for stratified air-water flows, with void fraction ranging from 0.1 to 0.9. A linear back projection algorithm was used to reconstruct the cross section image of the two-phase flow from the measured capacitance values. The reconstructed flow images obtained using this algorithm were compared to the real two-phase distributions. Filtering techniques were applied to the back projection algorithm in order to improve the reconstructed flow image quality. Limitations and possible future improvements of this technique are also discussed.
