Vapor-liquid equilibrium (VLE) data, dew points, bubble points, and critical points. 2. Core Models and Equations of State
Are you encountering any values?
You need new fluids (R1234yf, low-GWP), better mixture handling, or Python integration. nist refprop 9
REFPROP 9 has been widely cited in research and industry:
The software includes a vast library of pure fluids and mixtures. Users can define custom mixtures, allowing for the simulation of complex, real-world working fluids. 3. Comprehensive Property Suite It calculates a wide array of properties, including: You need new fluids (R1234yf, low-GWP), better mixture
Near the critical point, REFPROP 9 may struggle with iteration. If you receive an "iteration limit exceeded" error, switch the input to temperature-density (T,ρ) instead of temperature-pressure (T,p). Density remains single-valued in the two-phase region, even when pressure does not.
While NIST has since released newer iterations (such as REFPROP 10), Version 9 remains deeply embedded in industrial infrastructure. Many legacy enterprise software systems, automated scripts, and academic validation models are compiled explicitly around the Version 9 DLL. Because changes in software versions can cause minor shifts in calculated values due to updated fluid equations, many regulated industries maintain REFPROP 9 to ensure strict consistency with historical design data and certified calculations. Summary Table Specification / Detail National Institute of Standards and Technology (NIST) Primary Use Calculation of thermodynamic and transport properties Pure Fluids 100+ (hydrocarbons, refrigerants, cryogens, water, etc.) Max Components Up to 20 fluids in a single custom mixture Core Models Mixing Rules and Interaction Parameters
) for calculating the thermophysical properties of fluids. While newer versions (like REFPROP 10) are currently available, Version 9.0 remains widely cited in research for its accurate modeling of refrigerants, industrial chemicals, and natural gas mixtures. National Institute of Standards and Technology (.gov) Key Features of REFPROP 9 Property Calculations
For the most critical pure fluids, REFPROP 9 utilizes wide-range equations of state explicit in Helmholtz energy. These equations are empirical formulations based on thousands of high-precision experimental data points. They map out fluid behavior from the triple point up to temperatures of several thousand Kelvin and pressures reaching into the gigapascals. Mixing Rules and Interaction Parameters