Development of electro-void fraction meters for mini-channel

Watanabe, Hironori; Mitsutake, Toru*; Kakizaki, Sadayuki*; Takase, Kazuyuki

Capacitance type electro-void fraction meters with various shapes of electrodes were developed for two-phase flow measurement in tubes of 1mm in the smallest diameter. Ring and wire- type electrodes were applied to measure void fraction. The principle of the meter is that the electrical capacitance of a gas-liquid two-phase flow changes with void fraction. A high-frequency power supply enables to measure the low electrical capacitance of the water including pure water. It was confirmed by the air-water two-phase flow experiments that void fraction can be obtained in real time way every 50 millisecond. Void fraction in the experiment ranged from 0 to higher than 0.9. The void fraction was correlated with the electric capacitance by a linear function for the ring-electrode and hyperbolic function for the opposite wires-electrode under the atmospheric condition.