Prediction of void fraction in steady horizontal stratified flow

Abstract

The one-dimensional two-fluid momentum equations are used to predict the liquid surface profile in steady co-current stratified flow of gas and liquid in a horizontal tube and rod bundle tube. For given gas and liquid flow rates, the liquid surface profile is predicted in relation to three reference levels, namely the equilibrium and two critical levels. The void fraction in a series of stratified flow tests is predicted using the fact that the separation tank at the test section outlet in the test facility imposes a free fall condition on the liquid phase. Good agreement between the predicted and observed void fractions is obtained. For the same test conditions, the void fraction is also predicted in a CANDU reactor fuel channel type geometry where the channel ends in vertical pipe instead of a separation tank. For this geometry, the predicted channel void fraction is found to be significantly lower than that for a geometry with a separation tank.