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Development of gas–liquid two-phase flow pattern sensor of coalbed methane based on the principle of triboelectric nanogenerator

During the mining of coalbed methane (CBM), real-time measurement conducted by a gas–liquid two-phase flow pattern sensor is one of the key steps in the development of a reasonable discharge and mining system. In this study, a self-powered flow pattern sensor based on the triboelectric nanogenerator (TENG) was proposed and analyzed. The basic principle is as follows: when the sensor is impacted by the bubbles of the two-phase flow, triboelectric charges are generated due to the contact between the copper electrode, which plays the dual roles of electrode and positive triboelectric material, and the PTFE which acts as negative triboelectric material. This is transferred to produce voltage signals, thus realizing the measurement of the bubbles. On this basis, the characteristics and duration of the bubbles were further analyzed to measure the two-phase flow pattern. In addition, relevant characteristic parameters of the sensor were determined through analysis and experiment; when the product of the volume and velocity of the bubbles is greater than 608 cm 3 · cm s − 1 and the impact frequency is less than 0.45 Hz, the sensor can be used normally. We also explored the possibility of using the sensor to collect the impact energy of the bubbles to be used by other devices. As indicated by subsequent experiments on the sensor, it performs in a stable manner and can be used to measure the gas–liquid two-phase flow pattern, showing broad application prospects in the field of CBM.