Relative importance of entrained liquid fraction and mass transfer at the interface on pressure drop of annular flows

Fully developed adiabatic two-phase flows are commonly encountered in practice and their modeling is of primary importance for accurate, local calculations of pressure gradients and void fraction for the design of several industrial applications as heat exchangers and long fluid transfer piping. For large void fractions, the entrainment of liquid droplets into the vapor core can have a large effect on the pressure gradients. In this paper starting from theoretical considerations about the modeling of the pressure gradients in an annular two-phase flow, a numerical analysis as well as a discussion are proposed in order to quantify the relative importance of the entrainment on the calculations and to address further experimental studies and models on this topic.