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NIST REFPROP 9 (Reference Fluid Thermodynamic and Transport Properties Database) is a legacy version of the gold-standard software used by engineers and scientists to calculate the thermophysical properties of pure fluids and mixtures. While it has been largely superseded by Version 10.0, it remains a common citation in academic research and industrial simulations. Key Functions & Capabilities
Fluid Selection: Allows users to select pure fluids, pseudo-pure fluids, and predefined mixtures.
Property Modeling: Calculates essential data including density, entropy, enthalpy, and compressibility factors.
Mixture Customization: Users can define new mixtures by name and composition, or change specific mixture parameters to fit specialized research needs. nist refprop 9
Phase Coverage: Provides accurate data across liquid, gas, and supercritical phases. Common Applications
REFPROP 9 is frequently integrated into broader engineering software environments for complex modeling: Answers to Frequently Asked Questions - NIST Pages
Developed by the National Institute of Standards and Technology (NIST), REFPROP is a computer program that provides tables and plots of thermodynamic and transport properties for a wide variety of fluids and fluid mixtures. NIST REFPROP 9 (Reference Fluid Thermodynamic and Transport
It doesn't rely on simple, "back-of-the-napkin" calculations. Instead, it utilizes the most accurate physical models currently available, primarily the Helgerud-Mixon Equation of State (EOS) for pure fluids. This ensures that the data you pull—whether it's density, heat capacity, or surface tension—is as close to the experimental reality as physically possible.
RP = ctypes.windll.LoadLibrary(r"C:\REFPROP\refprop.dll")
| Feature | REFPROP 9 | REFPROP 10+ |
|---------|-----------|--------------|
| GUI | Classic, functional | Modern, tabbed |
| Fluids | ~105 | ~150+ |
| Mixture model | GERG-2008 | GERG-2008, EOS-CG, others |
| Python support | Manual DLL | Official refprop Python package |
| Plotting | Basic 2D | Enhanced 2D + 3D |
| Cost | One-time purchase (legacy) | Subscription or perpetual | What is NIST REFPROP
Stick with v9 if: You have legacy code, need only standard refrigerants, or prefer simple interface.
Upgrade to v10+ if: You need new fluids (R1234yf, low-GWP), better mixture handling, or Python integration.
Unlike many academic calculators, REFPROP 9 was designed for integration. It includes:
win32com).This made REFPROP 9 the backbone of many larger simulation environments, including Aspen Plus, EES (Engineering Equation Solver), and Dymola.