Refprop 9 — Nist

Viscosity, thermal conductivity, surface tension, and dielectric constant. 2. Mixture Modeling and Accuracy

| Feature | REFPROP 9 (Legacy) | REFPROP 10 / 10.0 (Current) | | :--- | :--- | :--- | | | ~147 | 200+ (including carbon capture solvents and new low-GWP refrigerants) | | Mixture Model | GERG-2008 (excellent for natural gas) | GERG-2012 (improved for CO2-rich mixtures) | | Transport Properties | Stable, mature correlations | Novel models for ionic liquids and nanorefrigerants | | User Interface | Classic, simple Windows GUI | Modernized with live plotting and tabular exports | | Programming | 32-bit and 64-bit DLL | 64-bit only; Python wrappers improved | | License Cost | No longer for sale (legacy users only) | Active sales; academic discounts available |

For advanced data analysis and hardware-in-the-loop testing.

As of 2024, . The current version is 10.0 (build 2024-04-15). However, owners of a legacy license can often redownload version 9 from the NIST official website using their original credentials. nist refprop 9

Unlike simpler correlations, REFPROP 9 uses fundamentally based equations of state (EOS), such as the Helmholtz energy formulation. It allows users to calculate:

The software handles pure fluids and complex multi-component mixtures. This makes it indispensable for chemical processing, refrigeration design, and aerospace engineering. Core Capabilities and Supported Fluids

The "secret sauce" of NIST REFPROP 9 lies in its use of . For a pure fluid, the dimensionless Helmholtz energy is a function of density and temperature. From this single function, all other thermodynamic properties can be derived via exact partial derivatives. As of 2024,

Methane, ethane, butane, pentane, and heavier alkanes.

REFPROP 9 includes a for external calls from:

NIST REFPROP 9 is a computer program, distributed as a database, that calculates the thermodynamic and transport properties of industrially important fluids and their mixtures. The program uses highly accurate mathematical models to predict how fluids behave under varying temperatures, pressures, and densities. It democratized access to reference-quality data

Employed for fluids with limited experimental data.

NIST REFPROP 9 holds a special place in engineering history. It arrived during a transition period where computing power was finally sufficient to run full Helmholtz equations in real-time on a desktop PC. It democratized access to reference-quality data, moving it from national labs to small engineering firms.