Free __full__: Refprop 91

NIST invests heavily in experimental data collection.

Version 9.1 was a major release in 2013, but it has since been superseded by Version 10 . While some third-party sites might list "free trials" for 9.1, these are often just installers for the "mini" version or unofficial files that NIST does not support. Why People Still Search for 9.1 refprop 91 free

: The current version has superseded 9.1. It includes 147 pure fluids and significantly optimized Fortran code for faster calculations and better convergence. NIST invests heavily in experimental data collection

If you cannot obtain a licensed REFPROP, consider these free/open options (varying in accuracy and available fluids): Why People Still Search for 9

: Includes a massive library of fluids and mixtures.

REFPROP (Reference Fluid Properties) is the industry standard for calculating the thermodynamic and transport properties of industrially important fluids and their mixtures.