Using Multiparameter Equations of State for Pure Substances

Abstract

During the last several years, accurate multiparameter equations of state have become a common data base for thermodynamic properties both in scientific and industrial applications. This development has been fueled not only by the general increase in the available computing power but also by the availability of corresponding software. Today, interactive programs are available which support common Microsoft Windows^® data exchange formats both for numerical and graphical results. These programs are widely used as replacements for printed data tables and charts. When thermodynamic properties have to be included in process calculations directly, Dynamic Link Libraries (DLL’s) are often used in combination with, e.g., Microsoft Excel^® sheets. This technique enables calculations of thermodynamic properties within spreadsheets — calculating thermodynamic properties becomes almost as convenient as calculating trigonometric functions in this way. At the same time, the use of classical source code libraries for the calculation of thermodynamic properties, where the user has to specify his or her own main program and very often has to deal with problems depending on features of special compilers, is retrogressive and is becoming increasingly restricted to applications where the computational speed is a major criterion. Finally, there is still a small number of users who develop their own programs since they have special requirements either with regard to the code or with regard to the algorithms.