Relationship Between Void Fraction and Electrical Characteristics in Gas-Liquid Two Phase Flow

The purpose of this study is the calibration in normalization technique for the real-time measurement of void-fraction inside fluid by using VC system at each temperature condition. There is an existing method of measuring electrical response called a VC system. A VC system is a voltage applied current measured system. The VC method measures electrically between electrodes attached around the measurement subject and detects internal distribution from impedance difference of the component to be measured. We deal with water and air in this research. In this method, we measure the difference between the electrical characteristics of air and water. And the measurement technique is requirement of pre-measurement. In homogeneous case, we need to measure current for normalization with real-time measured current. This method has problem that the impedance of water depends on the temperature. So the impedance of water at pre-measurement is different as compared real-time impedance. That’s why, the technique for measuring void-fraction is not high accuracy at present. The measurement technology should be improved to obtain more accurate area of air inside fluid. This requirement is achieved by real-time measurement and real-time separation based on the different electrical properties of air and water while calibrating with temperature. In order to improve accuracy of the proposed method, we conducted a system comparison experiment before calibration with temperature and after calibration. In conclusion, we could measure the void fraction in real time more accurately.