The prediction of dispersed flows boundaries in liquid-liquid and gas-liquid systems

A unified approach for predicting the transition to dispersed flow patterns in gas-liquid and liquid-liquid systems is suggested. It is based on the r evised models for predicting the maximal drop size in a turbulent field whi ch account for the holdup of the dispersed phase. Examining the range of ap plicability of the various models for transition to dispersed flow indicate s that it is determined by the Eotvos number, Eo(D) = Delta pgD(2) /8 sigma . Comparisons with available experimental data for gas-liquid and oil-water systems show that these models are capable of predicting the effects of fl uids' physical properties, tube diameter and inclination. The models sugges t a non-monotomic effect of the tube diameter on the critical fluids: flow rates, which implies that the up-scaling of data should be approached with care. (C) 2001 Elsevier Science Ltd. All rights reserved.