ABSTRACT
Gas–liquid two-phase flows are characterized by the presence of a moving and deforming gas–liquid phase interface. The heat released or absorbed during a gas–liquid phase change, per unit mass, is represented by the latent heat of vaporization. Phase change in gas–liquid flows occurs in many scientific and industrial systems such as boilers in thermal power plants, cooling systems in nuclear reactors, heat pumps, refrigeration systems, quenching in materials processing, among many others. Differences in thermophysical properties lead to various boiling curves for different fluids. Selected thermophysical properties of different solids, gases, and liquids are shown in Appendices D–F, respectively. Annular flow is characterized by the presence of a liquid film along the channel wall and gas flow within the inner core of the channel. The conservation equations of annular flow can be subdivided and written separately for each of the liquid and gas phases.
