EES is a commercial engineering tool that includes a fluid property library similar to REFPROP. The Free Demo version allows you to solve small problems and access most fluid properties, though the number of data points is limited.
Released in the early 2010s, REFPROP 9.1 was a significant update. It included:
The current version (10.0 or 11.0) has more features, but 9.1 remains popular because older hardware can run it and legacy tutorials reference it.
If the cost of REFPROP is a barrier, consider: refprop 91 free
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.
In the world of chemical engineering, HVAC design, and cryogenics, few tools are as revered as NIST REFPROP (Reference Fluid Thermodynamic and Transport Properties Database). Developed by the National Institute of Standards and Technology (NIST), REFPROP is the industry standard for calculating the properties of pure fluids and mixtures.
Version 9.1 (REFPROP 9.1) is a specific release that many users search for, hoping to find a "free" copy. The search term "refprop 91 free" is searched thousands of times monthly by students, engineers, and hobbyists who cannot afford the commercial license. EES is a commercial engineering tool that includes
But does a legitimate, free version of REFPROP 9.1 exist? And if you find a download link, should you use it?
While accessing software for free might seem appealing, the risks associated with unofficial sources often outweigh the benefits. For critical engineering work, accuracy and reliability are paramount, making licensed, professional software tools like REFPROP indispensable. Exploring official channels, discounts, or alternative open-source tools is recommended.
I’m unable to provide a write-up that promotes or facilitates the use of REFPROP 9.1 (or any version) through unauthorized “free” downloads, cracks, or keygens. REFPROP is a proprietary software package developed by the National Institute of Standards and Technology (NIST), and using it without a proper license violates NIST’s copyright and terms of use. The current version (10
However, I can offer a legitimate informational write-up about REFPROP 9.1, its capabilities, and how to access it legally — including free/low-cost options if they exist.
If you only need saturation properties for pure fluids (not mixtures), the NIST Chemistry WebBook is the official, free source. While it lacks the REFPROP GUI, you can look up:
When you search Google or torrent sites for "refprop 91 free," you will find links to executable files, keygens, and patch files. Here is what you are actually downloading: