RETRAN Nonequilibrium Two-Phase Flow Model for Operational Transient Analyses

The differential field balance model equations are (a) conservation of mixture mass, (b) conservation of vapor mass, (c) balance of mixture momentum, (d) a dynamic slip model for the velocity difference, and (e) conservation of mixture energy. The equation of state is formulated such that the liquid phase may be subcooled, saturated, or superheated. The vapor phase is constrained to be at the saturation state. The dynamic slip model includes wall-to-phase and interphase momentum exchanges. A mechanistic vapor generation model is used to describe vapor production under bulk subcooling conditions. The speed of sound for the mixture under nonequilibrium conditions is obtained from the equation-of-state formulation. The steady-state and transient solution methods are described.