Refprop 91 Free Fixed Jun 2026

RefProp 9.1 is a legacy version of the software. While NIST has since released version 10.0, many engineers and researchers still look for 9.1 due to its compatibility with older plugins, Excel macros, or specific research citations. Why RefProp Isn't Free

If you are looking for a free way to use REFPROP capabilities, NIST provides a specific "Mini" version for educational purposes: Mini-REFPROP : This is a free sample version intended as a teaching tool for students. Limited Fluids : It includes a restricted set of fluids such as water, cap C cap O sub 2 cap R 134 a

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While version 9.1 was revolutionary, REFPROP 10 offers significant advancements that are crucial in 2026: Improved mixtures (e.g., CO with impurities for CCS applications).

| Software | Pros | Limitations | |----------|------|--------------| | | 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 | — | RefProp 9

If you are looking for reliable, accurate, and legal thermophysical property data, the best practice is to acquire the current version through the official NIST website.

The software utilizes highly accurate mathematical equations of state, primarily using the , to compute vital data points like density, enthalpy, entropy, viscosity, and thermal conductivity. Version 9.1 was rolled out as a major milestone update, introducing optimized thermodynamic subroutines, enhanced vapor compression cycle models, and smoother integration for external programming languages. The Reality of "Free" Downloads Limited Fluids : It includes a restricted set

Official "free" versions are extremely limited or intended for trial: NIST Reference Fluid Thermodynamic and Transport Properties

If you are a professional engineer using a cracked version of REFPROP 9.1 at work, your company faces fines up to $150,000 per instance for software copyright infringement under the Digital Millennium Copyright Act (DMCA). NIST actively audits large engineering firms.

Revenue maintains professional developer support. The Hidden Dangers of "REFPROP 9.1 Free" Downloads

Implements the most accurate models available for pure fluids and mixtures, largely based on reference-accuracy equations of state.