Experimental and modeling studies for gas-liquid two-phase flow at high pressure conditions

Experimental and model studies were performed on two-phase flow behavior at high-pressure conditions. The experiments were conducted using nitrogen and water in a test loop of 106.4 min diameter pipe with inclination angles of 0degrees, 1degrees, and 3degrees at 2060 kPa. The liquid holdup data of 81 runs for each inclination angle were analyzed to identify the flow pattern. The mechanistic model developed for low pressures was modified for high-pressure conditions. The model first detects the flow pattern, and then calculates liquid holdup and pressure drop based on the flow pattern. For dispersed-bubble flow, the critical bubble size mechanisms were also applicable at high pressures to predict a flow region in the flow pattern map, and the slip model of liquid holdup showed better matches with the experimental data than the non-slip model. For stratified flow, the flow region in the flow pattern map extended to higher liquid flow rates than at low pressures. Sequential application of the Taitel-Dukler and Bendiksen-Espedal criteria could correctly identify the stratified and non-stratified flow transition, and the Lockhart-Martinelli correlation based on the shear stresses could evaluate the liquid holdup much better than the common correlation based on the material balance. Elongated-bubble flow changed directly into dispersed-bubble flow as the liquid flow rate increases. Excellent performance of the model was demonstrated by error analyses of liquid holdup and pressure drop calculations.