Prediction of holdup in liquid slugs

Correlations and models from the literature for the prediction of void fraction in liquid slugs are reviewed. It is shown that a mechanism that can explain the slug aeration in vertical, horizontal and inclined tubes has not yet been established. A new model that attributes the aeration of the liquid slug to a recurrent bubble entrainment from the Taylor bubble (TB) tail is introtuced. The bubble fragmentation is related to the rate of turbulent kinetic energy in the shear layer, which is formed at the TB wake as the liquid film plunges into the slug front. The model has been tested against experimental data available from the literature and was found to predict the effects of liquid and gas flow rates and physical properties, as well as tube diameter and inclination on the void fraction.