Measurement of voidfraction in dispersedbubblyflowcontainingmicro-bubbles with the constantelectriccurrentmethod

摘要

Voidfraction is one of the dominant parameters of gas–liquid two-phase flow in industrial equipment. An electric sensing method based on the difference in electric conductivity and permittivity between liquid and gas is one of the online measurementmethods of void faction. However, the previous constantelectriccurrentmethod is not applicable to dispersedbubblyflow because bubbles are dispersed in three dimensions. In the present study, the new constantelectriccurrentmethod available to the three dimensional dispersedbubblyflow with tiny bubbles (micro-bubbles) is developed. The proposed method to estimate the voidfraction is based on Maxwell’s theory and polarization of tiny bubbles. The method makes it possible to measure the voidfraction of three dimensional dispersedbubblyflow. It is experimentally clarified that the present proposed method with the constantelectriccurrentmethod can be applicable to measure the voidfraction of three dimensional bubblyflow more accurately than the previous constantelectriccurrentmethod. It is also clarified that Maxwell’s theory and the present proposed method with polarization are compatible with the drift flux model although voidfraction estimated with the previous method is higher than the drift flux model for three dimensional dispersedbubblyflow.