On the pressure drop calculation during the flow of two-phase non-azeotropic mixtures

Abstract

• The effect of changes in the properties of the liquid and vapor phase during the flow of zeotropic mixture on the pressure drop. • The use of the equations of state of the liquid and vapor phases of a zeotropic mixture in the calculation of flow acceleration. • The approach has been developed for calculating the pressure gradient distribution and phase composition during the flow of a vapor-liquid zeotropic mixture. This article discusses the distinctive features of non-azeotropic vapor-liquid flows. It is shown that for the correct calculation of the pressure drop, the change in the thermophysical properties of the liquid and vapor phase along the flow must be taken into consideration. A calculation method that allows one to take the effect of a change in the composition of phases on the pressure drop and reasonably select a friction model for a two-phase flow has been proposed. In this method, the change in flow acceleration is calculated using the equations of state of the mixture for the liquid and vapor phases under phase equilibrium conditions. The method was verified. The calculation results are compared with experimental data from open sources for a non-azeotropic mixture of methane-ethane.