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For the traditional electrical resistance tomography systems, the contact between the electrodes and the liquid may result in electrode corrosion, which limits the application of electrical resistance tomography in the industry. In this paper, a new electrical resistance tomography system based on a capacitivelycoupled contactless conductivity technique is developed. The conductivity distribution of the liquid between electrodes can be measured without direct contact with the liquid. The sensor is designed and the finite element method model is developed. Based on this model, the sensitivity fields are calculated and the structure of sensor is optimized. The data acquisition system is designed based on the phase-sensitive demodulation method. Experimental results show that the conductivity distribution images can be reconstructed, and the real-time performance of the system is evaluated.

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Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM) is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow) are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers’ works.

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