Modeling the transient outlet pressure and mass flow during flashing of HCFC-22 in a small nonadiabatic vessel

A model was derived from basic thermodynamic principles to describe the rate of depressurization within a small vessel. Major assumptions for the model included negligible kinetic and potential energy terms, saturated conditions within the vessel, and equal phase velocities through the exiting orifice. The two-phase homogeneous equilibrium and homogeneous frozen models, along with the single-phase model were used to predict the mass flux. A verification of the model was provided against available experimental data. Model predictions showed that the orifice size, initial refrigerant amount, and wall heat transfer have a more significant impact on the depressurization process than initial pressure and vessel volume for the test conditions.