Effect of steam condensation on countercurrent flow limiting in nearly horizontal two-phase flow

An analytical model that includes the steam condensation effect has been de rived and a parametric study has been performed. In addition, a series of e xperiments were performed and a total of 34 experimental data for the onset of countercurrent flow limiting (CCFL) in nearly horizontal countercurrent two-phase flow have been obtained for various flow rates of water. Compari sons of the present CCFL data with slug formation models show that the agre ement between the present as well as the existing model and the data is abo ut the same. However, the deviation between Taitel and Dukler's model predi ctions and the data is the largest when j(f) < 0.04 m s(-1). A parametric s tudy of the effect of condensation using the present model shows that, when all local conditions are similar, the model predicted local gas velocities that cause the onset of flooding are slightly lower when condensation occu rred. Based on the visual observation and the evaluation of the present wor k, it has been concluded that the criterion derived for the onset of slug f low can be directly used to predict the onset of inner flooding in nearly h orizontal two-phase flow within the experimental ranges of the present work . (C) 2000 Elsevier Science S.A. All rights reserved.