Gaseq has been around since for some years and I'm afraid its interface still has a Windows 3.1 look to it. New features have been added over the years, but the Help file is still a little incomplete. Gaseq can be used on any 32 bit Windows system: 95, 98, NT, ME and 2000 and XP.
Excel interface
Now
programmed using COM rather than the obsolete DDE. I have taken
advantage of the increased capabilities of the programming method to
plot a graph of the results of Auto-incremented calculations. An X-Y
plot is generated with the X being the first property specified
(usually the incremented one) and the others appearing as many Ys.
Two Y scales are used: concentrations (mole fractions) are plotted
on a log scale and the other properties, e.g. temperature, on a
linear one. It is very difficult to provide a graphing facility
which meets all requirements and it is inevitable that it will
usually be necessary to edit of the graph within Excel to improve
its appearance and utility. There have been difficulties with the
Excel interface when using the later versions of Excel, but I hope
the current Gaseq version (later than 28 July 2001) has put these
right.
New species
You can use any species in a
thermodynamic calculation if you have its elemental composition, its
enthalpy and entropy at 298K and its specific heat (Cp) at various
temperatures. Only a single polynomial is fitted (the standard NASA
form used two temperature ranges) so that the facility is useful for species which are
significant only at low temperatures. This covers most organic
molecules, but for new high temperature inorganic species you will
have to use a more sophisticated method. It is also possible to make
a database entry for a "fuel" by entering is elemental
composition and its heat of combustion. You can then use it as a
reactant in a combustion calculation, but clearly it cannot be used
as a product.
Reactants with different
temperatures
Each reactant species can have a different
temperature. The average temperature of an unreating mixture can be
calculated using the "UniformT" button if required ( an
otherwise tedious calculation), but this is done automatically
before most equilibrium calculations.
Specify product concentrations
(constrained equilibrium)
When one or more product species
reacts too slowly to be part of an equilibrium, this facility allows
the equilibrium among the rest of the mixture to be calculated.
It
is particularly useful for soot, which is present above equilibrium
in some rich flames.
Specify the number of moles of
product
This is to handle "super-equilibrium"
concentration of radicals which occur just after the reaction zone
in low and moderate presssure flames. The reactions which
interchange radical species (H, OH, O, etc.) are fast and
equilibrated, but the recombination reactions which remove radicals
are slow. The former do not change the number of species but the
latter do, allowing a radical overshoot to be modelled.
Use mass units
Species
concentrations can be entered and displayed in mass units. The
reactants and products boxes change to a lurid blue colour to remind
you that you have changed from a chemist into an engineer and are
not using molar units.
Calculate viscosities and thermal
conductivities
The thermal conductivities for diatomic and
polyatomic molecules calculated are low by about 10% compared with
those calculated by CHEMKIN using the online
transport properties calculator. This is probably because the
Mixture-Averaged method is used rather than the more rigorous
Multicomponent formulation.
Folder structure
The
folder which contains Gaseq.exe can now be read only, and a "local"
folder is used to store any files generated by the user. This is set
by clicking "Set local folder" on the File menu. The
initialization file Gaseq.ini is no longer used and the settings for
the program (such as the thermodynamic data files used and the
window sizes) are stored separately for each user in the Registry.
These changes are to facilitate sharing of the program on a
network.
Use with an external program without a user interface (Blind mode)
The blind mode is mentioned in the Help file, but only if you know
where to look, and then rather briefly.
Run an example problem in Gaseq and save as a .eq file. This can act as an input file as well, and can do so without much of the data.
Edit the eq file and Open it from Gaseq to make sure that you have left sufficient information for it to Calculate properly. This is not as logical as it should be; missing out some things confuses the parsing. For adiabatic and compression temperature calculations you need to provide a very rough estimate. See here for an example cut-down data file.
Your external program will need to write a file with this format and then call Gaseq with a command line:
Gaseq /e filename.eq
You will need to ensure that Gaseq is on your executables Path, that the filename is sufficiently specified and maybe that you have quotes around file names containing spaces. These are just normal DOS requirements. You can test it from Start/Run if you get this right.
The file will be updated to the full result of the calculation, and you will have to parse it to extract the information you require.