ASCEND IV is both a large-scale object-oriented mathematical modeling environment and a strongly typed mathematical modeling language.
Although ASCEND has primarily been developed by Chemical Engineers, great care has been exercised to assure that it is domain independent. ASCEND can support modeling activities in fields from Architecture to (computational) Zoology.
ASCEND includes a selection of standard models focussed on the chemical engineering domain. It also includes what is thought to be the largest open-source thermodynamic properties library.
Freesteam is a library that allows you to calculate water and steam properties using the industry-standard IAPWS-IF97 steam tables. Includes Python support.