To write a function to extract all 14 co-efficients and calculate the values of temperature enthalpy and entropy for all the species in the file

OBJECTIVE :

The main objective of the following matlab program is to write a function to extract all 14 co-efficients and calculate the values of temperature, enthalpy and entropy for all the species in the file.

In this program the molecular weights of the species will also be displaed in the command window.

MAIN CODE:

The code her demonstates the use of file parsing of the given NASA thermodynamic variables and plotting various graphs for data in O2, N2, CO2 species for enthalpy, temperature and entropy.

The code for the program is as follows

close all
clear all
clc

f1 = fopen(\'THERMO.dat\',\'r\');
fgetl(f1);

% Defining temperature values 
templ = str2num(fgetl(f1)); %#ok<ST2NM>
global_low_temp = templ(1);
global_mid_temp = templ(2);
global_high_temp = templ(3);    

% For skipping unwanted lines
 for i = 1:3
     fgetl(f1);
 end
 
 % Loop creation to read the values and plot molecular weight
 
 for i = 1:4:212
     line1 = fgetl(f1);
     
     l = strsplit(line1, \' \');
     m = length(l);
     species = l{1};
     
     % Storing the values of the local temperature values
     low_temp = str2double(l(m-3));
     mid_temp = str2double(l(m-2));
     high_temp = str2double(l(m-1)); % Check this later
     
     % Storing the values of the second line of variables
     
     line2 = fgetl(f1);
     % Finding the position of E
     
     a = strfind(line2,\'E\');
     
     % Reading all the other variables 
     a1 = str2double(line2(1:(a(1)+3)));
     a2 = str2double(line2((a(1)+4):(a(2)+3)));
     a3 = str2double(line2((a(2)+4):(a(3)+3)));
     a4 = str2double(line2((a(3)+4):(a(4)+3)));
     a5 = str2double(line2((a(3)+4):(a(5)+3)));
     
     % Storing the values of the 3rd line
     
     line3 = fgetl(f1);
     % Finding the position of E
      
     b = strfind(line3,\'E\');
      
     % Storing the values for the next set of variables
     a6 = str2double(line3(1:b(1)+3));
     a7 = str2double(line3((b(1)+4):(b(2)+3)));
     a8 = str2double(line3((b(2)+4):(b(3)+3)));
     a9 = str2double(line3((b(3)+4):(b(4)+3)));
     a10 = str2double(line3((b(4)+4):(b(5)+3)));
     
     % Storing ther values of the 4th line
     
     line4 = fgetl(f1);
     
     % Finding the position of E
     
     c = strfind(line4,\'E\');
     
     % Storing the values of variables in line 4
     
     a11 = str2double(line4(1:c(1)+3));
     a12 = str2double(line4((c(1)+4):(c(2)+3)));
     a13 = str2double(line4((c(2)+4):(c(3)+3)));
     a14 = str2double(line4((c(2)+4):(c(4)+3)));
     
     % Creating Temperature values for lower and higher temperature
     
     lower_temp = linspace(low_temp,mid_temp,100);
     higher_temp = linspace(mid_temp,high_temp,100);
     
         
     % Value of the universal has constant in j/mol*K
     R = 8.314; % Universal Gas Constant
     
     % Calculating the values for cp, H and S using the given formulas
     for k = 1:100 
         
% lower temperature values for cp,h,s calculations
cp_low(k)=(a8+(a9*lower_temp(k))+(a10*(lower_temp(k)^2)+(a11*(lower_temp(k))^3)+a12*(lower_temp(k))^4))*R;
h_low(k)=(a8+(a9*lower_temp(k))/2+(a10*lower_temp(k)^2)/3+(a11*lower_temp(k)^3)/4+a12*(lower_temp(k)^4)/5+(a13/lower_temp(k)))*R*lower_temp(k);
s_low(k)=((a8*log(lower_temp(k))+(a9*lower_temp(k))+((a10*lower_temp(k)^2)/2)+((a11*lower_temp(k)^3)/3)+((a12*lower_temp(k)^4)/4)+a14)*R);


% higher temperature values for cp,h,s calculations         
cp_high(k)=(a1+(a2*higher_temp(k))+(a3*(higher_temp(k)^2)+(a4*(higher_temp(k))^3)+a5*(higher_temp(k))^4))*R;
h_high(k)=(a1+(a2*higher_temp(k))/2+(a3*higher_temp(k)^2)/3+(a4*higher_temp(k)^3)/4+(a5*(higher_temp(k)^4))/5+(a6/higher_temp(k)))*R*higher_temp(k);
s_high(k)=((a1*log(higher_temp(k))+a2*higher_temp(k)+((a3*higher_temp(k)^2)/2)+((a4*higher_temp(k)^3)/3)+((a5*higher_temp(k)^4)/4)+a7)*R);

     end
 
 
 % Making Folders for saving the plots
 
 nasa_graphs = species;
 mkdir(nasa_graphs);
 current = pwd;
 cd(nasa_graphs);
 
 % Plotting the graphs
 
 % For specific heat 
 figure(1)
 plot(lower_temp,cp_low,\'linewidth\',3)
 hold on
 plot(higher_temp,cp_high,\'linewidth\',3)
 hold off
 title([\'Temperature vs Specific Heat\',species])
 xlabel(\'Temperature\');
 ylabel(\'Specific Heat\');
 legend(\'low temperature\',\'high temperature\');
 fig = sprintf(\'Specific Heat of %s.png\',species);
 saveas(gca,fig);
 
  % For Enthalpy 
 figure(2)
 plot(lower_temp,h_low,\'linewidth\',3)
 hold on
 plot(higher_temp,h_high,\'linewidth\',3)
 hold off
 title([\'Temperature vs Enthalpy\',species])
 xlabel(\'Temperature\');
 ylabel(\'Enthalpy\');
 legend(\'low temperature\',\'high temperature\');
 fig = sprintf(\'Enthalpy of %s.png\',species);
 saveas(gca,fig);
 
  % For Entropy 
 figure(3)
 plot(lower_temp,s_low,\'linewidth\',2)
 hold on
 plot(higher_temp,s_high,\'linewidth\',2)
 hold off
 title([\'Temperature vs Entropy\',species])
 xlabel(\'Temperature\');
 ylabel(\'Entropy\');
 legend(\'low temperature\',\'high temperature\');
 fig = sprintf(\'Entropy of %s.png\',species);
 saveas(gca,fig);
 cd(current)
 end

 % Calculating molecular weight
 
 atoms = [\'H\',\'C\',\'N\',\'R\',\'S\'];
 atom_weight = [1.00784 12.0109 16.002 39.065 32.067];
 mol_weight = 0;
 species_check = char(species);
 for i=1:length(species_check)
     for j=1:length(atoms)
         if (strcmp(species_check(i),atoms(j)))  
             mol_weight = mol_weight + atom_weight(j);
             position = j;
         end
     end
 x = str2double(species_check(i));
 if x>1
      mol_weight = mol_weight + (atom_weight(j)*(x-1));
 end      
 fprintf(\'Molecular weight of %s is : %f \\n\',species_check,mol_weight)
 end 

EXPLAINATION:

1. The code uses the thermodynamic data values from the file thermo.dat that was provided to me.

2. This file was read with the help of the read command for files and was read line by line.

3. For getting values for various species the program used loops for manipulating the values to an extent of the number of iterations that have to be taken into account.

4. the co-efficients are arranged ina fixed order and we have found the exact positiions with the help of strfind command in matlab and using the find variable to be E.

5. We have made a folder with the help of mkdir command

6. We have assigned certain values to the variables in the file and plotted themp against various temperature values vs enthalpy, entropy.

7. The images were saved in .JPEG format with the help of the saveas command.

PLOTS:

The first set of plots include the plots for CO2.

TEMPERATURE VS ENTHALPY

TEMPERATURE VS SPECIFIC HEAT

TEMPERATURE VS ENTROPY

The second set of plots are given for N2

TEMPERATURE VS ENTHALPY

TEMPERATURE VS SPECIFIC HEAT

TEMPERATURE VS ENTROPY

The third set of plots are for O2

TEMPERATURE VS ENTHALPY

TEMPERATURE VS SPECIFIC HEAT

TEMPERATURE VS ENTROPY

The below image shows the presence of all the graphs that were automatically generated when the program was executed.

The screenshot is as follows:

CONCLUTIONS:

The thermo.dat file was read and the needful operations were performed. The values for ther various coefficients were extracted and used as per guidance.