MCCCS Towhee (fitcoex)



    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.
    fitcoex is compiled using the Utility Makefile.
      cd /towheebase/Utils
      make fitcoex
    This will create the fitcoex executable which can then be run from the command line.
    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
Return to the Utility Summary page


Send comments to: Marcus G. Martin

Last updated:July 26, 2013