Click to close the wizard. You can now launch the REFPROP graphical user interface (GUI) from your desktop shortcut or Start Menu to verify that the core application functions correctly. Configuring Windows Environment Variables

REFPROP 9.1 includes a built-in Excel add-in, which is created automatically during the installation process for newer versions. In the software's installation folder (e.g., C:\Program Files (x86)\REFPROP\ ), there should be a file named .

Click and paste the exact path to your REFPROP directory (e.g., C:\REFPROP or C:\Program Files (x86)\REFPROP ). Click OK on all open windows to save the changes.

: Add the REFPROP directory to your system's "Path" variable to allow the system to locate the REFPROP.DLL Linking REFPROP 9.1 with Microsoft Excel

: Use the executable provided with your purchase (often via CD-ROM or digital download). Default Directory : By default, it installs to C:\Program Files (x86)\REFPROP

Installing is a straightforward process, but its utility depends on correct pathing and integration with your calculation tools. By following the steps above, you’ll have a robust thermodynamic engine ready for complex fluid analysis.

This happens if the program doesn't know where the /fluids folder is. Go to the REFPROP GUI, select Options > Paths , and ensure the path points to your installation folder.

NIST REFPROP (Reference Fluid Thermodynamic and Transport Properties) is the industry standard for calculating the thermophysical properties of fluids and fluid mixtures. While newer versions exist, REFPROP 9.1 remains widely used in engineering, research, and academic environments due to its stability and legacy integration with external software.

Create a new user environment variable named RPPrefix and set its value to your installation path (e.g., C:\Program Files\REFPROP ).

: Go to the Developer tab and click on Excel Add-ins .

Note: Even on 64-bit Windows, REFPROP 9.1 installs to the Program Files (x86) folder because it is a 32-bit application.

To call REFPROP from any command line or external program, add it to your System Path: