File Parsing

Introduction

Through research and experimentation NASA has proposed functions for specific heat at constant presuure(Cp) , enthalapy(H) and entropy(S) which can be defined by knowing 14 coefficients that define the function . Term.dat file provided by NASA is used to calculate these thermodynamic properties .

Aim

Aim of the project is to read the therm.dat file which is in chemkin format , and use those values to plot variation of various thermodynamic properties with temperature , calculate their molecular mass ,and store the plot in specific directories with name as specie name .

Inputs

The only input is the therm.dat file .

Output

Output contains directories representing each of the species in therm.dat file and contain plots of various themodynamic properties named and saved only by running the code .

Temperatures
Global min ,mid and max temperature in the header of the file are extracted by using strsplit to split the line containing the three temperatures and white space is used to split them and str2num is used to convert string to floating point number .

Specie Name

fgetl is used to read the line containing the name of the specie and strsplit is used to split all the words before first white space to get the specie name.

Extracting Coefficients

Each coefficient is extracted using their position relative to each \'E\' in line .findstr command is used to find \'E\' and as each coefficient has fixed decimal places so relative position of starting and ending digit can be found and then str2num is used to convert it to a floating point number.Embeded for loops are used to find other coefficients and for other species in similar way .

New directory and saving

mkdir command is used to make new directory of the name same as that of specie and cd command is used to browse between different directories. saveas command is used to save the generated plots.

Molecular Mass

strcmp is used to compare various members of the name of specie and the Global set of elements. Logic used is that if any string member in specie name matches with the elements , its coreesponding mass is added to the molecular mass , which is initially set to 0 ,and c is count of number of times the same element appears.The molecular mass is written in a text file in the directory of the corresponding specie.


Code

Following is the matlab code formulated for this project

clear all
close all
clc
f1 = fopen(\'THERMO.dat\',\'r\')
%skipping the header
file_header=fgetl(f1);
%reading the Temperatures
Temp = fscanf(f1,\'%f\' ,[1 3]);
low_temp = Temp(1);
mid_temp = Temp(2);
high_temp = Temp(3);
%leave comment lines
comment_1 = fgetl(f1);
comment_2 = fgetl(f1);
comment_3 =fgetl(f1);
comment_4 = fgetl(f1);
for i=1:53
    specie_name_line = fgetl(f1);
    space = strfind(specie_name_line,\' \');
    
    specie = specie_name_line(1:space(1)-1);
    %reding coeffs
     tline1 = fgetl(f1);
     b = strfind(tline1,\'E\');
     a(1:14)=0;
     a=a\';
     
     a(1) = str2num(tline1(1:b(1)+3));
    for j=2:5
    
      
        a(j) = str2num(tline1(b(j-1)+4:b(j)+3));
        
    end
    tline2 = fgetl(f1);
    b = strfind(tline2,\'E\');
    a(6) = str2num(tline2(1:b(1)+3));
    for k=7:10
    
      j=k-5;
        a(k) = str2num(tline2(b(j-1)+4:b(j)+3));
        
    end
    tline3 = fgetl(f1);
    b = strfind(tline3,\'E\');
    a(11) = str2num(tline3(1:b(1)+3));
    for l=12:14
        j=l-10;
        a(l) = str2num(tline3(b(j-1)+4:b(j)+3));
    end
    R= 8.314;
    folder_name = specie;
    mkdir(folder_name);
    T = linspace(1,5000,50);

  for j=1:length(T)

   if T(j)< mid_temp

       Cp = R*(a(1)+a(2).*T+a(3).*T.^2 + a(4).*T.^3+a(5).*T.^4);

       H = R.*T.*(a(1)+(a(2).*T)./2+(a(3).*T.^2)/3+(a(4).*T.^3)/4+(a(5).*T.^4)/5+(a(6)./T));

       S = R.*(a(1)*log(T)+(a(2).*T)+(a(3).*T.^2)/2+(a(4).*T.^3)/3+(a(5).*T.^4)/4+(a(7)));

   else

      Cp = R.*(a(8)+a(9).*T+a(10).*T.^2+a(11).*T.^3+a(12).*T.^4);

      H = R.*T.*(a(8)+(a(9).*T)/2+(a(10).*T.^2)/3+(a(11).*T.^3)/4+(a(12).*T.^4)/5+(a(13)./T));

      S = R.*(a(8).*log(T)+(a(9).*T)+(a(10).*T.^2)/2+(a(11).*T.^3)/3+(a(12).*T.^4)/4+(a(14)));

   end
  end
 
  %plotting Graphs
  figure(1);
  title(specie);
  plot(T,Cp);
  xlabel(\'T\');
  ylabel(\'Cp (specific heat at constant pressure)\');

  figure(2);
  title(specie);
  plot(T,H);
  xlabel(\'T\');
  ylabel(\'H (enthalapy)\');

  figure(3);
  title(specie);
  plot(T,S);
  xlabel(\'T\');
  ylabel(\'S (entropy)\');
  molecular_mass = mol_mass(specie);
  cd (specie);

  saveas(1,\'Cp vs T.jpg\');
  saveas(2,\'H vs T.jpg\');
  saveas(3,\'S vs T.jpg\');
  
  f3 = fopen(\'mmass\' , \'w\');
  fprintf(f3 , \'molecular mass of \');
  fprintf(f3 ,specie);
  fprintf(f3 , \' = \');
  fprintf(f3 , num2str(molecular_mass));
  
  fclose(f3);
 cd ..;
 
 disp(specie)
 disp(molecular_mass)
 
 
end

function [M_W] = mol_mass(specie)

R_elem= {\'H\',\'C\',\'N\',\'O\',\'A\'};
A_W = [1 12 14 16 40];

M_W = 0;
for i = 1:length(specie)
    for j = 1:length(R_elem)
        if strcmp(specie(i),R_elem(j))
            M_W = M_W+A_W(j);
            c = j;
        end
    end
    n = str2num(specie(i));
    if n>1
        M_W = M_W+A_W(c)*(n-1);
    end
end

Results

Following are resulting plots for O2 ,N2 and CO2

O2

following plot shows variation of Cp with temperature


following is the plot for enthalapy with temperature

following is the plot of entropy(S) with Temperature

N2

following is the plot for Cp vs T

following is for H vs T

following is for S vs T

CO2

following is Cp vs T for CO2

following is curve showing H vs T for CO2

following shows the curve for S vs T for CO2