|link| - Refprop 91 Free

NIST REFPROP 9.1 is proprietary software and is not officially available for free; it requires a paid license from the National Institute of Standards and Technology (NIST). While version 9.1 is a widely used legacy version, it has been officially superseded by Version 10 , which currently costs approximately for a single-user license. Official Procurement Options

If you require REFPROP for professional or academic accuracy, you should obtain it through official channels: New License (Version 10): Available for $325.00 from the NIST Standard Reference Data Store

If you already own a legitimate copy of version 9.x, you can upgrade to version 10 for a discounted price of Trial Version:

NIST historically provided a limited "Mini-REFPROP" for educational use, though full version 9.1 functionality typically requires purchase. Free Alternatives to REFPROP refprop 91 free

If you are looking for free, high-accuracy thermodynamic fluid properties, the following open-source tools are widely recommended by the engineering community: REFPROP | NIST

How to Obtain REFPROP 9.1 Legally Today

NIST no longer sells version 9.1 — they sell version 10.0 (2023). To use REFPROP legitimately:

1. Purchase REFPROP 10.0 from NIST (~$375).
2. Check your university/employer’s license — many institutions have site licenses.
3. Use the REFPROP Demo (limited properties, water only) available on request from NIST.

Availability and Cost

The official REFPROP software is not free. It requires a license to use, which can be purchased from NIST. The cost can vary depending on the type of license (e.g., personal, academic, or commercial) and the number of users. NIST REFPROP 9

1. CoolProp (The Best Open-Source Alternative)

What it is: CoolProp is an open-source, cross-platform thermophysical property database. It is not a "crack" – it is legitimate and peer-reviewed.

• Fluids: Over 120 pure fluids (including most REFPROP fluids).
• Mixtures: Yes, full support.
• Accuracy: Tuned to the same NIST standards as REFPROP. Many engineers have validated CoolProp results against REFPROP 9.1 with a deviation < 0.1%.
• Interfaces: Python, MATLAB, Octave, C++, Excel, and a standalone GUI.
• Cost: Free (LGPL license).
• Download: Visit www.coolprop.org.

The REFPROP Demo (Version 9.1 or earlier)

• What it is: A limited-time or limited-feature trial.
• Limitations: Usually restricted to only 5–10 pure fluids (the most common refrigerants like R134a, R410A, and water). Mixture capability is disabled or limited to 2 components. Some properties may be "grayed out."
• Legality: This is the only "free" version of REFPROP 9.1 offered by NIST.

If you find a website offering "REFPROP 91 free full version with crack," you are looking at pirated software.

Legal Low-Cost / Free Alternatives

If you need similar functionality without cost: How to Obtain REFPROP 9

| Software | Pros | Limitations | |----------|------|--------------| | CoolProp | Open-source, high-accuracy, many fluids, Python/MATLAB/C++/Excel | No official GUI (but third-party ones exist) | | NIST Refprop Online | Free, web-based | Single-phase pure fluids only, no mixtures | | ThermoState (Python) | Simple interface, free | Limited fluids vs. REFPROP | | REFPROP Lite (if released) | Not available | — |

CoolProp is widely considered the best open-source alternative and can reproduce most REFPROP results within 0.1% for common fluids.

REFPROP 9.1 – Overview and Legal Access

REFPROP (Reference Fluid Thermodynamic and Transport Properties) is NIST’s standard reference database for thermodynamic and transport properties of pure fluids and mixtures. Version 9.1 (released around 2013) was a significant update, adding new fluids, enhanced mixture models, and improved computational routines.