EES provides properties for many pure refrigerants and a few refrigerant mixtures such as R407C, R410A, and ammonia-water. The National Institute of Standards and Technology (NIST) has developed REFPROP (also called NIST Standard Reference Database 23), which provides high accuracy property data for pure refrigerants and refrigerant mixtures. Included in the database are the "natural" refrigerants, carbon dioxide, ammonia, propane, isobutane and other hydrocarbons. REFPROP also provides high accuracy data for mixtures such as ammonia-water and most organic refrigeration mixtures. REFPROP uses the most advanced methods for estimating property data. Transport properties as well as thermodynamic properties are provided in all fluid regimes, including compressed liquid and near critical states. 

An interface has been developed for REFPROP versions 6 and newer that allows the NIST property data base to be used with the equation-solving and other features of EES. If you are involved in modeling refrigeration systems, you will find the NIST REFPROP program and the EES_REFPROP interface to be of considerable interest. Contact NIST to order REFPROP. The current version of REFPROP is version 8. The EES_REFPROP interface is available for $1,000 from F-Chart Software.

F-CHART Software has developed interfaces for other NIST Database programs, including NIST 4, NIST 12, and NIST 14. Contact F-Chart Software for availability and pricing.