CoolProp

CoolProp is an open-source thermophysical property database that provides functions to calculate thermodynamic and transport properties of various fluids, including refrigerants, pure fluids, pseudo-pure fluids, and humid air. It offers functionality similar to commercial software like REFPROP but is free and open-source. The library currently ships as version 7.2.0 and sees regular releases with performance improvements, bug fixes, and support for newer Python versions.