| Input values for the
calculation Fundamental
equations expressed in the form of the Helmholtz energy
usually need temperature T and density ρ
as input values to calculate thermodynamic properties.
Due to the fact that in technical applications different
input values are given in most cases, the program FLUIDCAL
contains iterations with which input values of the combinations
(T,p), (T,h), (T,s),
(p,ρ), (ρ,h),
(ρ,s), (p,h), (p,s)
and (h,s) can be handled in the homogeneous
region as well as in the vapour-liquid two-phase region.
These iterations calculate the missing values of temperature
T and density ρ with which all other
properties can be calculated.
For
the most important input values (T,p)
and (T,ρ) it is possible to calculate
directly all properties listed above. 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 above can be calculated depending on every possible
combination of input values. In the two-phase region
the program calculates the stable two-phase-system values
for those properties listed in the table above.
On the vapour-liquid
phase boundary the properties temperature, pressure,
and density can be used as input values. 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 for the evaluation of the saturated-liquid
and saturated-vapour density and the corresponding functions
for the calculation of the desired property depending
on 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 depending on pressure are
implemented. It is also possible to calculate directly
the saturation temperature depending on the saturated-liquid
or saturated-vapour density.
The software FLUIDCAL for the calculation of thermodynamic
properties
To easily
integrate the fundamental equations in Windows based
standard programs, the program FLUIDCAL contains a dynamic
link library (DLL). The DLL contains more than sixty
functions that allow the calculation of the 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.
The call is made via simple functions whose names are
based on the property to be calculated and the given
input variables. Thus, the density ρ for
given values of temperature T and pressure p
is calculated from the function DOTP.
FLUIDCAL
contains a .LIB file that allows to integrate the DLL
into user specific Fortran, C programs and Visual Basic.
In addition,
FLUIDCAL contains an Add-In file that allows a simple
integration of the DLL into Microsoft Excel.
The following
screenshot shows the calculation of the enthalpy on
the example of the function HOTP(T,P,SUBNR) for given
values of temperature and pressure. By using the Add-In,
the considered properties can be directly calculated
under Excel by calling the name of the corresponding
function. In addition to the input quantities T
and p, the number of the substance must be
given. In the example shown in the screenshot it is
number 1 for the substance methane.
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Call of
functions from a FLUIDCAL DLL with the help of
an Add-In in Excel.
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All property
functions of the DLL are described in detail in the
MANUAL.PDF that is part of the software.
The software
FLUIDCAL is not free of charge (Exeption for universities:
FLUIDCAL for water according to the IAPWS-95 formulation.
Information on a free download is given here.).
The software
FLUIDCAL is marketed by the company F.I.R.S.T. GmbH,
see below. However, the software can also be ordered
by the Chair of Thermodynamics.
The interactive
program ThermoFluids
The interactive
PC-program ThermoFluids was developed for users who
occasionally need to calculate thermodynamic properties
and who prefer to work with predefined Windows based
programs. This program is based on FLUIDCAL containing
the substances and calculable properties listed in the
tables above. Further information is given here.
Contact:
Prof. em. Dr.-Ing. W. Wagner Tel.:
+49 (0)234 32-29033
Fax: +49 (0)234 32-14945
E-Mail: wagner@thermo.rub.de
Contact FIRST GmbH:
F.I.R.S.T. - Gesellschaft für technisch-wissenschaftliche
Softwareanwendungen mbH
Telegrafenstr. 11
42929 Wermelskirchen
Telefon: +49 (2196) 88 778 0
E-Mail:
Info@FIRSTGmbH.de
Sales@FIRSTGmbH.de
Homepage: www.FirstGmbH.de
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