Refprop 10 Free Download 2021 'link' -

REFPROP (Reference Fluid Thermodynamic and Transport Properties) is a widely used software library from the National Institute of Standards and Technology (NIST) that provides thermophysical properties (equations of state, transport properties, mixture models) for pure fluids and mixtures. REFPROP 10 is a major version released by NIST that includes updates to fluid models, mixture parameters, and software interfaces.