Abstract:
In this thesis, the experimental results of flow pattern, void fraction and pressure drop of gas-liquid flow in the narrow concentric annuli are presented. The transparent test sections with inner diameters of Di = 8, 10 and 11 mm, outer diameter of Do = 12.5 mm, and overall length of 880 mm are used. The inclination angle of the test sections are 0 = oO, 30' and 60' with the horizontal plane. Air and water are used as the test fluids. The gas and liquid superficial velocity is varied in a range of Us, = 0.0218-65.4 ds and Us, = 0.069-6.02 ds, respectively. The plug, slug, annular/slug, annular, bubbly/plug, bubblylslug-plug, slughubbly and dispersed bubbly two-phase flow patterns can be observed in these experiments. The experimental results show that the slughubbly flow pattem is presented only in the case of 0 = 30' and 60' and the flow patterns are only slightIy affected by the annular gaps. The effects of the inclination angle and the annular gap on the flow regime maps, void fraction and pressure drop are studied. It is found that as the inclination angles increases the slug/bubbly flow pattem occurs at the lower Us,. In addition, void fraction decreases and pressure drop increases with increasing inclination angles. With the decrease of the annular gap, the transitions of all flow patterns occur at the higher Us, and Us,. However, void fraction and pressure drop increase with decreasing annular gaps.The measured void fractions for the test sections are compared with predictions of several empirical correlations. For the test sections of Do = 12.5 mm and Di = 8 rnm, the correlation proposed by CISE group gave the most accurate prediction, while the homogeneous model gave the best prediction for the test sections of Do = 12.5 mm, Di = 10 and 11 mm. The measured prcssure drops are also compared with predictions of several empirical correlations. For the test sections of Do = 12.5 m and Di = 8 and 10 mm, the homogeneous model gave the most accurate prediction, while the LockhartlkMartinelli-ehisholm correlation gave the best prediction for the test sections of Do = 12.5 m, Di = 11 mm.