9 | Nist Refprop

It is used for high-stakes thermal modeling in space technology, such as the MIRI cryocooler

The software calculates properties such as viscosity , thermal conductivity , and surface tension using fluid-specific correlations or friction theory.

When NIST REFPROP 9 was released, it marked a substantial upgrade from its predecessor, Version 8. It reflected years of research by the Thermophysical Properties Division at NIST. The changes were not merely cosmetic; they fundamentally improved the way mixtures were calculated, which is often the most challenging aspect of thermodynamics.

It can compute over 40 properties, including enthalpy, entropy, density, speed of sound, and Joule-Thomson coefficients. Supported Fluids and Mixtures nist refprop 9

In the worlds of chemical engineering, HVAC design, natural gas processing, and academic research, the accuracy of fluid properties is non-negotiable. A 1% error in enthalpy or density can cascade into a catastrophic failure in heat exchanger design or a multimillion-dollar miscalculation in a refrigeration cycle. For over three decades, engineers and scientists have turned to one authoritative source: .

REFPROP stands for . It is a software program and database that calculates the thermodynamic and transport properties of pure fluids and their mixtures. Unlike simple lookup tables or ideal gas approximations, REFPROP uses complex Helmholtz energy equations of state (EOS) . These equations allow the software to predict properties in gas, liquid, superheated, and two-phase regions with uncertainty levels rivaling experimental measurement.

The "NIST" stamp guarantees traceability. For most pure fluids, the uncertainty in REFPROP 9 is: It is used for high-stakes thermal modeling in

As of 2024-2025, NIST REFPROP 10.1 is the current version. So why do people still use version 9?

This article explores the capabilities, technical underpinnings, and enduring legacy of NIST REFPROP 9, detailing why it remains a critical tool for scientists and engineers around the globe.

REFPROP 9 uses a physical CD-ROM or a hard-drive key (HASP) for copy protection depending on the license. If you have an old installer, ensure you keep your license file (e.g., rppref9.dll or license key). The changes were not merely cosmetic; they fundamentally

Note to users: REFPROP 9 does not include newly developed refrigerants like R1233zd(E) or R1336mzz(Z) – those came in version 10.

REFPROP is not free. It is a paid, copyrighted software. As of the release of REFPROP 10, NIST no longer sells new licenses for version 9, but existing licensees can continue using it. A standard single-user license historically cost around $325 for academic use and $975 for commercial use.