Software FluidCal for Calculation of Thermophysical Properties for a Large Number of Substances

The program FluidCal was developed for the calculation of thermodynamic properties from equations of state (fundamental equations of state in the form of the Helmholtz free energy) in research and for technical applications. For more than 95 substances, the software enables the calculation of 17 thermodynamic properties, three partial derivatives and for a number of substances (see the list in Table 1) also the calculation of dynamic and kinematic viscosity, thermal conductivity, Prandtl number, thermal diffusity and surface tension. All combinations of temperature T, pressure p, density ρ, specific enthalpy h, and specific entropy s can be selected as input variables for the calculations of thermodynamic properties.

Information about the use of the software under the various Windows operating systems and Excel versions as well as the integration of the available 32-bit or 64-bit Fortran DLL using Excel Add-Ins and 32-bit .NET DLL are given in Section 4 of this software description.

Detailed information about the current distribution channel by the engineering office Dr.-Ing. N. Kurzeja and its contact address can be found at the end of this website.

1. Equations of state for 96 substances covered by the Software FluidCal of version 2.4.2.0

In order to offer a calculation software for as many substances as possible, the FluidCal software package contains both the equations of state developed at the Chair of Thermodynamics of the Ruhr-University Bochum and equations of state by other authors. FluidCal is currently available for 96 substances, but will be continuously developed and can be expanded on demand at short notice.

When new reference equations of state are published for the substances integrated in FluidCal, they are immediately made available as an update for FluidCal, as happened, for example, for the important new equation of state for ammonia only a few days after its publication. With the current reference equations of state for hydrogen, ammonia and methanol and the associated transport equations for viscosity and thermal conductivity and the properties derived from them, FluidCal offers all the options for calculating  the thermophysical properties of the hydrogen transport chain quickly and easily with the highest degree of accuracy.

Similary, the FluidCal version 2.4.2.0 can now be used to quickly and easily calculate the thermodynamic and partly also the transport properties of all new low-GWP refrigerants such as R1224yd(Z) (GWP = 0.88, ODP = 0.00012), R1233zd(E) (GWP = 1, ODP = 0.00034), R1234yf (new 2022) (GWP < 1, ODP = 0), R1234ze(E) (GWP = 1, ODP = 0), R1234ze(Z) (GWP = 4, ODP = 0), R1243zf (GWP < 1, ODP = 0), R1336mzz(Z) (GWP = 2, ODP = 0) and R1336mzz(E) (GWP = 18, ODP = 0), which are used in some of the heat pump or ORC cycle processes that are important in light of the climate crisis.

  Table 1  List of the fundamental equations of state for 96 substances integrated in FluidCal.

   *    For substances marked with a star, in addition to the thermodynamic properties the
         transport properties dynamic and kinematic viscosity can also be calculated.

   ** For substances marked with two stars, in addition to the dynamic and kinematic viscosity,
         the thermal conductivity , the Prandtl number and the thermal diffusity can be calculated.

   °   For substances marked with ° , in addition the surface tension can be calculated.

   "   For substances marked with ", their equations were developed as part of a study on automated
        fitting techniques for fluids of industrial interest. Because of their limited data sets they are less
        accurate than normal reference equations of state optimized for one substance at a time.

  The high-GWP refrigerants R11, R12, R23, R113 and R116 can now only be integrated on special request.

If corresponding equations are available, the calculation of dynamic and kinematic viscosity, thermal conductivity, Prandtl number, thermal diffusivity or surface tension for substances not listed here can also be integrated or updated on request at short notice, as has currently been done for the transport properties of hydrogen, ammonia, methanol, ethanol, carbon dioxide, ethylene, propylene, R134a, R1234yf, R1234ze(E), R1224yd(Z), R1336mzz(E), R1233zd(E) or propylene glycol. The list with the respective current reference equations of state used in FluidCal,  a list of directly available further equations of state and the references of the equations for the transport properties including surface tension is given on the website references.

2. Calculable thermodynamic and transport properties

Table 2 lists the calculable thermodynamic properties and Table 3 shows the calculable transport properties.

 Table 2  Calculable thermodynamic properties.

 Table 3  Calculable transport properties, see
 footnotes of Table 1.

3. Input variables for the calculations 

3.1 Thermodynamic properties

Fundamental equations of the Helmholtz free energy are formulated as a function of the temperature T and the density ρ. However, since other input variables are mostly used for technical calculations, the FluidCal software package contains functions with which for the combinations of the input variables (T,p), (T,h), (T,s), (p,ρ), (ρ,h), (ρ,s), (p,h), (p,s) and (h,s) the respective missing variables temperature T and density ρ are calculated for the homogeneous region as well as for the two-phase region.

For the most important input variables (T,p) and (T,ρ) it is possible to calculate directly all properties listed in Table 2. To avoid a complex number of functions, the program contains routines for the direct calculation of the temperature T and density ρ from all combinations of input values. Combined with these functions, all other properties listed in this table can be calculated depending on every possible combination of the input values. In the two-phase region, the program calculates the stable two-phase-system values for those properties.

On the vapour-liquid phase boundary the properties temperature, pressure or density can be used as input variables. The most important thermodynamic properties can be calculated directly on the saturated-liquid and saturated-vapour phase boundary depending on temperature. It is possible to calculate all other properties on the phase boundary by combining the functions of the saturated-liquid and saturated-vapour density and the corresponding functions for the calculation of the desired property as a function of temperature and density. If for a certain case the vapour pressure is given, functions for the calculation of the saturation temperature and the saturated-liquid and saturated-vapour density as a function of pressure are implemented. It is also possible to calculate directly the saturation temperature as a function of the saturated-liquid or saturated-vapour density.

3.2 Transport properties

The transport quantities can be determined both in the single-phase region as a function of the input variables (T,p) and (T,ρ) and directly on the phase boundary as well as a function of the saturation temperature. The surface tension can be calculated in the liquid region as a function of the input variable (T).

4. FluidCal DLL and Excel Add-In for calculating thermodynamic and transport properties

For the integration of the fundamental equations of state supplied by FluidCal in Windows based standard programs, the FluidCal software package contains the dynamic link library (DLL) FLUIDCAL.dll, optimized and built with the Intel Visual Fortran Compiler XE 15.0.7.287. The DLL provides more than sixty functions that allow the calculation of the thermodynamic properties listed above for the single-phase region, within the vapour-liquid two-phase region (if thermodynamically reasonable), and along the saturated-vapour and saturated-liquid phase boundary for all combinations of the input variables T, p, ρ, h and s.

In addition, the FluidCal software package contains an Excel Add-In file that allows a simple integration of the DLL into Microsoft Excel. Since the installation of the FluidCal Excel Add-In adds all functions exported with the FluidCal DLL to the standard Microsoft Excel function set, the desired thermodynamic and transport properties can be calculated directly in an Excel spreadsheet by calling the abbreviated name of the corresponding function with the required input variables. Thus, the density ρ for given values of temperature T and pressure p (and additionally the substance number SUBNR listed in the manual) is calculated from the function call DOTP. All functions can be called either by direct input of the formula listed in the manual into an Excel spreadsheet or very conveniently with the help of the function wizard of Microsoft Excel.