Flooding in gas-liquid countercurrent two-phase flow in parallel vertical pipes

Flow regime transition and pressure drop in gas-liquid countercurrent two-phase flow was studied in three vertical parallel pipes. The conditions for flooding initiation in parallel pipe systems could be well predicted using Imura's correlation which for a single pipe. After flooding, the flow patterns were different in each pipe. A flow pattern classification diagram for the three-pipe system was developed, based on the flow patterns observed under various conditions of gas and liquid flow rates. It was seen from the results of pressure measurement in the three-pipe system that maximum pressure developed in each pipe had a serious effect on the average pressure in lower plenum, and that the frictional loss coefficient, which estimated from the time averaged pressure in lower plenum, could be corresponded to the relative gas Reynolds number. (author)