D5 Properties of Multicomponent Fluid Mixtures

D5.1 Calculation of Vapor–Liquid Equilibria

1 Introduction

For the design of processes, the knowledge of the vapor–liquid equilibrium (VLE) is essential in many cases, either to be able to detect the formation of a second phase or to quantitatively describe the properties of the coexisting phases in a two-phase process. The VLE of any given system depends strongly on composition as well as on temperature or pressure.

In this short chapter, only some basic fundamentals are presented. The principal thermodynamic relations forming the basis for VLE description are independent of the specifics of the substances dealt with. On the other hand, for models describing the substance-specific thermodynamic properties a variety of approaches are available and still under development. Here, only comparably simple systems can be dealt with, excluding e.g., polymers, electrolytes, surfactants, and biomolecules. The interested reader is referred to textbooks and specialized literature for further...