A method for direct thickness measurement of wavy liquid film in gas-liquid two-phase annular flow using conductance probes

Gas-liquid two-phase annular flow widely exists in industrial fields such as chemical engineering, petroleum, nuclear reactors and so on. The liquid film plays major influences on the performance of heat and mass transfer in gas-liquid two-phase annular flow. In this paper, a conductance probe with adjustable insertion depth is designed to measure the wavy liquid film thickness, which is a direct method unaffected by the change of conductance. Then, a calculation method of time-average liquid film thickness using duty ratio weight is proposed. The effects of the insertion depth increment and statistical time on measurement error are analyzed, and the mathematical expressions of relative error are derived. The verification experiments are carried out in the gas-liquid experimental facility at Tianjin University. Through the measurement error analysis, a system error compensation calculation method is presented, which improves the measurement accuracy obviously. The average relative error is better than 1.00% at different insertion depth increments in the statistical time T = 5 s. The proposed method does not need the real flow calibration because the relationship between liquid film thickness and conductance isn't involved in the process of measurement.