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Overview
This section explains the fitcoex utility program. This program is designed for use in conjunction with the towhee_vlcc output files in order to
compute the critical temperature and critical density from a sequence of single-component vapour-liquid simulations. Last updated for version
7.0.6.
Compiling
fitcoex is compiled using the Utility Makefile.
cd /towheebase/Utilsmake fitcoex
This creates the fitcoex executable that can is run from the command line.
Features
In order to successfully run fitcoex, two sources of input are required. The first is an input file (*.sim), which contains some comment lines, a value
for the critical exponent "beta", the towhee_vlcc data from at least 3 different temperatures, and a special end of file zero line. The second file
(*.exp) is optional and is for transforming experimental data into a similar format as the simulation data for comparison purposes.
An example with the input files and a for plotting the output is provided in the
Examples/VLCC_Fit directory.
File Format for the towhee_vlcc compilation file (*.sim)
- Line 1 comment line (typically has a comment about how the data was generated)
- Line 2 comment line (typically says 'beta' to remind the user that the beta value is on the next line
- Line 3 beta (double precision). I typically use a value of 0.325 for this variable
- Line 4 comment line (typically has a header for the vlcc data)
- Line 5 to 5+n towhee_vlcc data lines (double precision).
You must have at least 3 of these lines at different temperatures in order for the code to compute the critical properties.
- Line 6+n zero end line. The code only knows it has hit the end of the file when it gets a line that has a zero value for the variables.
9 double precision zeros go on this line.
File Format for the experimental data file (*.exp)
There are currently two experimental data file formats implemented into this routine. These files are translated into units of g/ml and output to
several files by fitcoex.
- Smith and Srivastava: This format is similar to the one used in the reference book
Smith and Srivastava 1986.
- Line 1 comment line
- Line 2 molecular weight of the molecule (g/mol)
- Line 3 comment line
- Line 4 comment line
- Line 5 to 5+n experimental temperature (K), liquid phase molar volume (ml/mol), and vapor phase molar volume (ml/mol).
- Hensel and Warren: This format is similar to the one used in the reference book
Hensel and Warren 1999.
- Line 1 comment line
- Line 2 molecular weight of the molecules (g/mol)
- Line 3-4 comment lines
- Line 5 to 5+n experimental temperature (C), saturation pressure (bar), liquid density (g/ml), vapor density (g/ml)
Run the code by typing
/towheebase/Utils/fitcoex
Return to the Utility Summary page
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