SPECS is a program for Separation and Phase Equilibrium Calculations developed for the Windows 32bit environment. The program has a friendly user interface. It integrates different thermodynamic models and algorithms used for performing phase equilibrium calculations for different systems. SPECS has models for complex mixtures such as polar and non-polar mixtures, oil mixtures, polymer-solvent mixtures and aqueous electrolyte solutions. The algorithms available in the program allow the user to calculate

  • Multiphase PT-flashes Phase envelopes Dew and bubble points
  • P-xy and T-xy diagrams
  • Binary, ternary and quaternary phase diagrams for aqueous electrolytes
  • Physical properties of aqueous electrolyte solutions
  • Solid-liquid equilibrium
  • Viscosities
  • Minimum miscibility pressures

SPECS also has algorithms for

  • Regression of binary interaction parameters for thermodynamic models Characterization of oils PVT experiments
  • Slimtube simulations
  • Investigating equilibria in petroleum reservoirs.

SPECS is equipped with a built-in database consisting of 100 components. A user may add a new component. The procedure of oil characterization may produce pseudo-components, or fractions. Different properties of the components may be specified in the program (the standard estimates are available for the database components):

The program operates with a wide range of equations of state and excess models, including original models developed and correlated in the Center, like the Cubic Plus Association EoS for mixtures of associating/non-associating compounds (G. Kontogeorgis) and the extended UNIQUAC for the mixtures containing electrolytes (K. Thomsen):

The program performs a great variety of tasks, depending on the type of mixture. Such calculations as multiphase flash are based on original fast and robust algorithms developed in the Center (M. L. Michelsen).

The output of the program is produced as a text file or as a plot. Presently work is being carried out in order to produce output in the form allowing for easy exchange with Excel (such an exchange is already available for the input)


Alexander Shapiro
Associate Professor
DTU Chemical Engineering
+45 45 25 28 81