Void fraction measurement of stratified gas-liquid flow based on multi-wire capacitance probe

Abstract

The void fraction of stratified gas-liquid flow is crucial to determine mixture density, calculate pressure gradient, obtain phase flow rate, analyze flow structure and monitor flow processes. The measurement and prediction of void fraction is of particular interest in many industrial processes. The objective of this paper is to develop a new method to accurately measure the void fraction in the stratified gas-liquid flow. A measurement device named multi-wire capacitance probe which is based on the single-wire capacitance probe is developed. The device can obtain the average void fraction as well as the local void fraction by measuring the water layer height at different circumferential positions of the pipe. We analyze the water layer height and its variations with time at different circumferential positions under different superficial gas and liquid velocity. We also discuss the local void fraction at different circumferential position and the average void fraction of the circular cross section by measuring the water layer height. Comparisons of ten existing prediction correlations using the measured void fraction are made. The correlation of Armand–Massina is recommended to predict the void fraction of stratified gas-liquid flow. The relative error of the void fraction predicted by this correlation is within ±3.0% under the 95.65% confidence level.