BEHAVIOR OF STEAM-CONDENSATE COUNTERCURRE NT 2-PHASE FLOW IN A VERTICAL PIPE

Steam-condensate countercurrent two-phase flow was studied in a vertic al steam pipe with a cooling pipe. The lower plenum pressure and distr ibution of coolant temperature in axial direction were measured. The p lenum pressure increases as the steam velocity increases, and attains a maximum when condensed water started to overflow from the top of pip e. For a further increase of steam velocity, the plenum pressure begin s to decrease and shows periodic oscillation in the case of low flow r ate of coolant. During overflow of the condensate, no steam emission w as observed from the pipe. The heat balance indicates the existence of a region in which the condensate might stay as a single phase.