COSMO-RS is a novel predictive method for the thermodynamic properties of pure and mixed fluids. In contrast to group contribution methods, which depend on an extremely large number of experimental data, COSMO-RS calculates the thermodynamic data from molecular surface polarity distributions, which result from quantum chemical calculations of the individual compounds in the mixture. The different interactions of molecules in a liquid, i.e. electrostatic interactions, hydrogen bonding and dispersion, are represented as functions of surface polarities of the partners. Using a novel, very rigorous and efficient thermodynamic solution for such pair-wise surface interactions, which goes beyond the limitations of the quasi-chemical approximation, COSMO-RS finally converts the molecular polarity information into standard thermodynamic data of fluids, i.e. vapor pressures, activity coefficients, excess properties, etc. Winning the COSMOlogic First Industrial Fluid Properties Simulation Challenge organized by NIST and AICHE/COMSEF, COSMO-RS has proven to be the most reliable and efficient tool for the prediction of activity coefficients and similar thermodynamic properties of demanding compounds.

Since COSMO-RS is getting increasingly accepted in chemical engineering thermodynamics, the demand for a direct link between the most advanced COSMO-RS implementation, i.e. our COSMOtherm program, became more and more apparent. Therefore we generated a CAPE-OPEN compliant interface between COSMOtherm and thermo packages of process simulators. Due to a lack of CAPE-OPEN compliance of the ASPEN software, the interface has a special mode of interaction with the ASPEN simulator.

The basic concept of the COSMOtherm-CAPE-OPEN interface, and examples of usage of COSMOtherm in different simulation environments will be presented.