FluidProp and REFPROP 10

June 14, 2018

FluidProp 3.0 for MS-Windows can now be used with NIST REFPROP 10. During execution FluidProp detecs automatically if REFPROP is available on your computer. Like REFPROP 9.x, REFPROP 10 integrates fluently with the other FluidProp libraries. However, now, the table of available fluids in FluidProp fits to the fluids of REFPROP 10 instead of those of 9.x. As a consequence, the FluidProp method GetFluidNames lists all fluids available in REFPROP 10, and, in case REFPROP 9.x is still used and one of the REFPROP 10 fluids is employed that is not avalable in 9.x, then an error message is sent by REFPROP.

The FluidProp RefProp Add-On, which integrates the RefProp 9.1 source code in FluidProp and adds additional functionality in the form of derivatives, which are not or not directly available in REFPROP, remains offering the RefProp 9.1 functionality for the moment. It will be upgraded to version 10 in the future. 

For detailed information on REFPROP 10, we refer to the REFPROP web page of NIST.

Please, go to your account page in order to download the latest version of FluidProp by just clicking the Download button in your FluidProp 3.0 Basic or Add-On records or (re)order a free version by clicking the Free button on the FluidProp Basic 3.0 web page.


Thermodynamics, Fundamentals and Engineering Applications

March 12, 2018

The Thermodynamics, Fundamentals and Engineering Applications textbook is soon to be released!

This concise text by William C. Reynolds (Stanford University) and Piero Colonna (Delft University of Technology, The Netherlands) provides an essential treatment of thermodynamics and a discussion of the basic principles built on an intuitive description of the microscopic behavior of matter. Aimed at a range of courses in mechanical and aerospace engineering, the presentation explains the foundations valid at the macroscopic level in relation to what happens at the microscopic level, relying on intuitive and visual explanations which are presented with engaging cases. With ad hoc, real-word examples related also to current and future renewable energy conversion technologies and two well-known programs used for thermodynamic calculations, FluidProp and Cycle-Tempo, this text provides students with a rich and engaging learning experience.

Please, keep an eye on our news items and the website of Cambridge University Press! You can find the book with accompanying video demos on the website of Cambridge University Press and on Amazon.com


FluidProp 3.1 for macOS (beta)

February 21, 2018

Shortly, FluidProp for macOS will be released as a beta version. It will be available with a limited number of fluids and for a limited time period. Aside from the regular C++ and Fortran programming interfaces, FluidProp is also available as Add-in for Microsoft Excel 2016 for Mac.

The various add-ons that are available for FluidProp 3.0 Basic for MS-Windows and interfaces for Pyhton and Matlab will be released for the macOS version coming months. For most users, the Basic version is sufficient, but the add-ons makes modeling more challenging situations possible. For complete information about FluidProp, check out the FluidProp main page.

The beta version of FluidProp 3.1 Basic for macOS offers the same thermodynamic models as the free FluidProp 3.0 Basic for MS-Windows.

Please, keep an eye on the news!


Thermodynamic properties of lithium bromide / water

June 1, 2017

A software package for the calculation of the thermodynamic properties of lithium bromide / water (LiBr/H2O) mixtures is currently under development.

Lithium bromide aqueous solutions have been a popular choice in the absorption cooling industry, because of their excellent thermodynamic characteristics. The use of the model is not only limited to the conventional absorption refrigeration applications but it extends well beyond unconventional operational ranges typical of various newly conceived absorption cycles, which are investigated by more and more researchers because they are relevant in terms of sustainability. Such systems, powered directly by solar collectors or by waste heat from industrial processes and prime movers, like gas turbines and reciprocating engines, yield a much higher conversion efficiency through the smart integration of energy systems.

The calculated properties are all based on a Gibbs free energy equation and are therefore thermodynamically consistent. Computations yield reliable results for solutions in the concentration range from 0 to 70% (weight) and temperatures from 0 to 210 °C with vapor pressures up to 1 MPa.

The software will be available as an Add-On to FluidProp. As FluidProp is seamlessly coupled with Cycle-Tempo, the thermodynamic properties of LiBr/H2O mixtures will be available to Cycle-Tempo simulations too, as component models have been adapted appropriately (an updated version of Cycle Tempo will also soon be released). 

The FluidProp Add-On, as well as the updated version of Cycle-Tempo, are expected to be available shortly. For more information, please contact us by sending an email to info@asimptote.com


Thermodynamic properties of hydrofluoroolefins now available in FluidProp

October 1, 2016
A new add-on to FluidProp is the Hydrofluoroolefins add-on. This add-on contains new hydrofluoroolefins, which have been developed in recent years. These fluids feature a low global warming and ozone depletion potential and can be suitable replacement candidates for foam blowing agents, fluids in heat pumps, air conditioning systems, refrigeration systems, and organic Rankine cycle systems.
The hydrofluoroolefins add-on in FluidProp contains a consistent set of complete thermodynamic models for four hydrofluoroolefins and one hydrochlorofluoroolefin. The hydro(chloro)fluoroolefins available in FluidProp are:


FluidProp name


IUPAC name




Chemical formula





















The thermodynamic models are based on both the iPRSV and the PCP-SAFT equation of state and can therefore be used in the (free)StanMix and PCP-SAFT libraries in FluidProp.


Thermodynamic properties of cyclic siloxanes now available in the siloxanes add-on

October 1, 2016

The Linear Siloxanes add-on to FluidProp has been replaced by the Siloxanes add-on. This add-on now also contains the cyclic siloxanes D3 (hexamethylcyclotrisiloxane), D4 (octamethylcyclotetrasiloxane), D5 (decamethylcyclopentasiloxane),  and D6 (dodecamethylcyclohexasiloxane), next to the already existing linear siloxanes, MM, MDM, MD2M, MD3M,MD4M,MD5M, and MD6M.
The thermodynamic models are based on both the iPRSV and the PCP-SAFT equation of state and can therefore be used in the (free)StanMix and PCP-SAFT libraries in FluidProp. The Siloxanes add-on fee has remained unchanged.

Transport properties available for FluidProp

March 4, 2015

We proudly present a new add-on to the FluidProp family: the Transport Properties add-on. It lets you calculate the dynamic viscosity and thermal conductivity for each fluid and each thermodynamic model in FluidProp. By releasing this new add-on we're fulfilling a wish that is often expressed by our users. Please go ahead an try it. It will be available at a reduced fee in the first period.

Derivatives free for academic users

July 18, 2014

As of today, the derivatives add-on is free for academic users. We noticed that many people want to use FluidProp from the Modelica.Media library but ran into problems because they were missing the derivatives add-on. As we think that dynamic simulation with Modelica is an important development in the sector, we decided to stimulate this by giving academic users free access to the derivatives.

If you are an academic user and you want to use FluidProp 3.0 basic with the derivatives add-on, please register as academic user and then select the educational version of the derivatives add-on.

FluidProp updates

14, 2014

Asimptote contributes to feasibility study of OTEC installation

March 7, 2014

Asimptote contributed to a feasibility study for an OTEC installation for BlueRise (see www.bluerise.nl). We developed a preliminary design for the OTEC turbine, using our advanced optimization procedures. Contact us if you want to learn more about our expertise in this field.

New version of FluidProp

Februari 3, 2014

Today we started distributing a new version of FluidProp (version 3). The main differences with earlier versions are:

  • fully 64-bit compatible (so it also works properly on newer versions of Windows)
  • extra thermodynamic models and fluids can be purchased as add-ons to the free version
  • the helpfile has been brought up to date.

Formally, the new FluidProp is still a beta, but we have been testing it with several users for some time. So we are confident that this will prove to be a stable new version of the popular FluidProp package. For those who wish to use the old version, it is still available through www.fluidprop.com.

New website

December 14, 2013

We are now testing our new website. Because of the increasing traffic on our old site and continued interest, we decided to provide a better service for our users by:

  • providing all the information about our services in a concise way,
  • providing more complete information on our software products so that users can see what is in it for them,
  • providing a webshop where you can download the free versions and demo versions of our software and where you can buy the full versions and add-ons.

Please help us test the new website. If you have any comments that will help us improve, we love to here from you through our contact form.