Extended irreversible thermodynamics applied to two-phase systems

The paper presents the method of derivation of constitutive equations based on the Classical and Extended Irreversible Thermodynamics. The method is explained for a single phase medium and then is applied to a two-phase one-component of a liquid and its vapour. The two-phase system is described by the simplest homogeneous model (HTPM). In this model it is assumed that the velocities of both phases are equal, the two phases coexist at any point of the system, and that the transport of the phases due to diffusion is negligibly small. It is shown that the Extended Irreversible Thermodynamics applied to the two-phase system provides an interesting equation for the evolution of the non-equilibrium dryness fraction x, comprising its second partial derivaties with respect to time and space. This equation is derived for HTPM for the first time.