Determination of void fraction in horizontal air-water two-phase flow using gamma ray attenuation technique

摘要

Gamma ray attenuation method is widely used non-intrusively for measuring void fraction in gas-liquid two-phase flow systems. In this study, single-energy gamma rays of activity 30mCi from caesium-137 were used to measure void fraction in a horizontal air-water two-phase flow system at ambient temperature. The study was done on a test rig made of PVC pipe of diameter 2.54cm. The gamma ray counts for the static calibrations and air-water two-phase flow mixture at various water flow rates were measured using thallium-activated Nal scintillation detector and the void fraction calculated. The trend of the results obtained compared well with existing trends. When the water flow rate was varied from 6L/min to 16L/min, at a constant air flow rate, the void fraction varied from 0.141 to 0.102 respectively. The experimental results were compared with those obtained from the use of the model of Chisholm to obtain the mean deviations. The error margins were in the range of 0.3% - 4.2%.