To access and interpret the data from a given file using Octave.

AIM:-

To access and interpret the Thermodynamic data from a given file using Octave.

Description:-

• File parsing is an important technique used for accessing and handling data in different applications.
• In the present application, the thermodynamic data is accessed to calculate various thermodynamic properties, and their variation with temperature is also observed.
• The properties calculated are Entropy, Specific heat, Enthalpy
• These values are calculated at different temperatures using the relations :

• Here,

R is the universal Gas constant,

T is the temperature at an instant,

Coefficients(a1-a7) are obtained from the data.

• The Molecular weight is calculated by considering the atomic weights of corresponding elements.

Procedure :

1. The given file is Loaded into octave using 'fopen' command with reading access and a file pointer is defined.
2. Next, 'fgetl' command is used to load the line into a variable.
3. Here for some lines 'fskipl' command is used to neglect the lines.
4. After loading 'strsplit' command is used to divide the single string into a cell array.
5. This cell array is then used to feed the data into different variables.
6. When needed 'str2num' command is used to convert alphabetical data into numerical data.
7. Next, this data is passed into a different function for sorting and separating.
8. The data is passed into different functions that process the input data and give corresponding thermodynamic properties.
9. In the function, the properties are calculated over a range of temperatures so that the version can be observed.
10. This output data is fed into files and the plots of variation are also generated.
11. The molecular weight of species is also calculated and printed onto the command window.
12. All this data is saved in corresponding directories that are created to be species-specific.
13. All the files are closed and the program is terminated.

Plots:

Code:

• Main code to access and initialize the data:

  clear all;
  close all;
  clc;
  
  
  f1=fopen('Thermo.dat','r');%opening the file
  count=fskipl(f1,Inf);%counting the lines in file by skipping them
  fseek(f1,0,SEEK_SET());%bringing the file pointer to start of the file
  %variable for maintaining the count of lines
  fskipl(f1);%skipping the firsr line
  
  %Getting the global temprature data
  line_1= fgetl(f1);
  Global_temps=strsplit(line_1," ");
  Global_low_temp=str2num(Global_temps{2});
  Global_medium_temp=str2num(Global_temps{3});
  Global_high_temp=str2num(Global_temps{4});
  
  %Skipping Header information
  for i=3:5
    fskipl(f1);
  endfor
  %Handling the species block
  for j=1:53 %maintaining count of species
    
    %Handling the first Line of species block
    species_line_1=fgetl(f1);
    temp=strsplit(species_line_1,'G ');%seperating the data
    temp_1=strsplit(temp{1});
    species_name(1,j)=strtrim(temp_1(1));%saving the species name
    temp_2=strsplit(temp{2});
    %storing local temprature ranges
    Local_Low_temp(1,j)=str2num(temp_2{2});
    Local_High_temp(1,j)=str2num(temp_2{3});
    Local_Medium_temp(1,j)=str2num(temp_2{4});
    
    %Handling the second Line of species block
    species_line_2=fgetl(f1);
    pos=strfind(species_line_2,"E");%seperating the data
    Low_a1(1,j)=(str2num(species_line_2(1:pos(1)+3)));%coverting alphabetical data into numerical data
    Low_a2(1,j)=(str2num(species_line_2(pos(1)+4:pos(2)+3)));
    Low_a3(1,j)=(str2num(species_line_2(pos(2)+4:pos(3)+3)));
    Low_a4(1,j)=(str2num(species_line_2(pos(3)+4:pos(4)+3)));
    Low_a5(1,j)=(str2num(species_line_2(pos(4)+4:pos(5)+3)));  
    
    %Handling the third Line of species block
    species_line_3=fgetl(f1);
    pos=strfind(species_line_3,"E");
    Low_a6(1,j)=(str2num(species_line_3(1:pos(1)+3)));%seperating the data
    Low_a7(1,j)=(str2num(species_line_3(pos(1)+4:pos(2)+3)));
    High_a1(1,j)=(str2num(species_line_3(pos(2)+4:pos(3)+3)));
    High_a2(1,j)=(str2num(species_line_3(pos(3)+4:pos(4)+3)));
    High_a3(1,j)=(str2num(species_line_3(pos(4)+4:pos(5)+3))); 
    
    
    %Handling the fourth Line of species block
    species_line_4=fgetl(f1);
    pos=strfind(species_line_4,"E");
    High_a4(1,j)=(str2num(species_line_4(1:pos(1)+3)));%seperating the data
    High_a5(1,j)=(str2num(species_line_4(pos(1)+4:pos(2)+3)));
    High_a6(1,j)=(str2num(species_line_4(pos(2)+4:pos(3)+3)));
    High_a7(1,j)=(str2num(species_line_4(pos(3)+4:pos(4)+3))); 
  endfor
  fclose(f1);
  mkdir "Thermo";%creating the parent directory
  
  
  %passing the data for printing and sorting
  fileparse(species_name,Low_a1,Low_a2,Low_a3,Low_a4,Low_a5,Low_a6,Low_a7,
  Local_Low_temp,Local_Medium_temp,Local_High_temp,High_a1,High_a2,High_a3,High_a4,High_a5,High_a6,High_a7);

• Code for displaying and saving data into subfolders :

  function fileparse(species_name,Low_a1,Low_a2,Low_a3,Low_a4,Low_a5,Low_a6,Low_a7,Local_Low_temp,Local_Medium_temp,Local_High_temp,High_a1,High_a2,High_a3,High_a4,High_a5,High_a6,High_a7)
    for i=1:53 %For iterating in between the diffrent species
      T=Local_Low_temp(i):Local_High_temp(i);%creating temprature ranges for each species
      
      
      %passing the data for caluclation of diffrent parameters for each species    
      cp= caluclate_cp(species_name(i),Low_a1(i),Low_a2(i),Low_a3(i),Low_a4(i),Low_a5(i),Low_a6(i),Low_a7(i),Local_Low_temp(i),Local_Medium_temp(i),Local_High_temp(i),High_a1(i),High_a2(i),High_a3(i),High_a4(i),High_a5(i),High_a6(i),High_a7(i));    
      H=  caluclate_H(species_name(i),Low_a1(i),Low_a2(i),Low_a3(i),Low_a4(i),Low_a5(i),Low_a6(i),Low_a7(i),Local_Low_temp(i),Local_Medium_temp(i),Local_High_temp(i),High_a1(i),High_a2(i),High_a3(i),High_a4(i),High_a5(i),High_a6(i),High_a7(i)); 
      s=  caluclate_s(species_name(i),Low_a1(i),Low_a2(i),Low_a3(i),Low_a4(i),Low_a5(i),Low_a6(i),Low_a7(i),Local_Low_temp(i),Local_Medium_temp(i),Local_High_temp(i),High_a1(i),High_a2(i),High_a3(i),High_a4(i),High_a5(i),High_a6(i),High_a7(i)); 
      mol_wt=mole(species_name(i));
  
      %Creating files for sperating the data
      name=char(species_name(i));
      mkdir("Thermo",name);%creating a file for particular species
  
      %opening the file
      cd Thermo;
      cd (name);
  
  
      %adding data into the file
      f1=fopen('Data.txt','w');%creating a text file for adding the data
  
      %Printing diffrent parameters into the text file
      fprintf(f1,['Species Name :%s\n'],name);
      fprintf(f1,"Molecular Weight : %f\n",mol_wt);
      fprintf("%5s - %f\n",name,mol_wt);%printing the molecular weights onto command window
      fprintf(f1,['Species Low Temp coefficients\n']);
      fprintf(f1,"a1=%5.6es\na2=%5.6e\na3=%5.6e\na4=%5.6e\na5=%5.6e\na6=%5.6e\na7=%5.6e\n",Low_a1(i),Low_a2(i),Low_a3(i),Low_a4(i),Low_a5(i),Low_a6(i),Low_a7(i));
      fprintf(f1,['\n\nSpecies Low Temp coefficients\n']); 
      fprintf(f1,"a1=%5.6e\na2=%5.6e\na3=%5.6e\na4=%5.6e\na5=%5.6e\na6=%5.6e\na7=%5.6e\n",High_a1(i),High_a2(i),High_a3(i),High_a4(i),High_a5(i),High_a6(i),High_a7(i));
      fprintf(f1,"\nLocal_High_temp=%d,\nLocal_Medium_temp=%d,\nLocal_Low_temp=%d\n",Local_High_temp(i),Local_Medium_temp(i),Local_Low_temp(i));
      
      %handling the caluclated parameters
      fprintf(f1,"The CP values are:\n");
      %printing thr specific heat values in the file
      for j=1:length(cp)
        fprintf(f1,"%5.6e\n",cp(j));
      endfor
      fprintf(f1,"The Enthalphy values are:\n");
      %printing thr Enthalphy values in the file
      for j=1:length(H)
        fprintf(f1,"%5.6e\n",H(j));
      endfor
      fprintf(f1,"The Entropy values are:\n");
      %printing the Entropy values in the file
      for j=1:length(s)
        fprintf(f1,"%5.6e\n",s(j));
      endfor
      fclose(f1);%closing the text file
  
  
  
      %Plotting the specific heat values
      plot(T,cp,'linewidth',3);
      xlabel(['\fontsize{20}Temprature']);
      ylabel(['\fontsize{20}Cp']);
      title(['\fontsize{25}Cp vs Temprature-' ' ' char(species_name(i))]);
      text=sprintf('%s.png',char(species_name(i)));
      saveas (gca,text);%saving the plot
      
      %plotting the Enthalphy data    
      plot(T,H,'linewidth',3);
      xlabel(['\fontsize{20}Temprature']);
      ylabel(['\fontsize{20}Enthalphy']);
      title(['\fontsize{25}Enthalphy vs Temprature-' ' ' char(species_name(i))]);
      text=sprintf('Enthal_%s.png',char(species_name(i)));
      saveas (gca,text);%saving the plot
      
      
      %plotting the Entropy data
      plot(T,s,'linewidth',3);
      xlabel(['\fontsize{20}Temprature']);
      ylabel(['\fontsize{20}Entropy']);
      title(['\fontsize{25}Entropy vs Temprature-' ' ' char(species_name(i))]);
      text=sprintf('Entro_%s.png',char(species_name(i)));
      saveas (gca,text);%saving the plot
      
      %closing the directory
      cd ..;
      cd ..;
    endfor
  endfunction

• Code for calculating specific heat:

  function c_p= caluclate_cp(species_name,Low_a1,Low_a2,Low_a3,Low_a4,Low_a5,Low_a6,Low_a7,Local_Low_temp,Local_Medium_temp,Local_High_temp,High_a1,High_a2,High_a3,High_a4,High_a5,High_a6,High_a7)
    %parameters used in formula
    T=Local_Low_temp:Local_High_temp;
    R=8.314; 
    
    %actual caluclations
     if(T<Local_Medium_temp) %low temprature region
        cp(1,:)=R.*(Low_a1+Low_a2.*T+Low_a3.*T.^2+Low_a4.*T.^3+Low_a5.*T.^4);
      else% High Temp region
        cp(1,:)=R.*(High_a1+High_a2.*T+High_a3.*T.^2+High_a4.*T.^3+High_a5.*T.^4); 
     endif 
     
     %passing the result parameters
     c_p=cp;
  endfunction

• Code for calculating Enthalpy:

  function c_p= caluclate_H(species_name,Low_a1,Low_a2,Low_a3,Low_a4,Low_a5,Low_a6,Low_a7,Local_Low_temp,Local_Medium_temp,Local_High_temp,High_a1,High_a2,High_a3,High_a4,High_a5,High_a6,High_a7)
    
    %parameters used in formula
    T=Local_Low_temp:Local_High_temp;
    R=8.314; 
    
     %actual caluclations
     if(T<Local_Medium_temp)%low temprature region
        cp(1,:)=R.*T.*(Low_a1+(Low_a2.*T)./2+(Low_a3.*T.^2)./3+(Low_a4.*T.^3)./4+(Low_a5.*T.^4)./5+Low_a6./T);
      else%High temprature region
        cp(1,:)=R.*T.*(High_a1+(High_a2.*T)./2+(High_a3.*T.^2)./3+(High_a4.*T.^3)./4+(High_a5.*T.^4)./5+High_a6./T); 
      endif 
       
     %passing the result data
     c_p=cp;
  endfunction

• Code for calculating Entropy:

  function c_p= caluclate_s(species_name,Low_a1,Low_a2,Low_a3,Low_a4,Low_a5,Low_a6,Low_a7,Local_Low_temp,Local_Medium_temp,Local_High_temp,High_a1,High_a2,High_a3,High_a4,High_a5,High_a6,High_a7)
    
    %parameters used in formula
    T=Local_Low_temp:Local_High_temp;
    R=8.314; 
    
    
    %actual caluclations
     if(T<Local_Medium_temp)%low temprature region
        cp(1,:)=R.*(Low_a1.*log(T)+(Low_a2.*T)+(Low_a3.*T.^2)./2+(Low_a4.*T.^3)./3+(Low_a5.*T.^4)./4+Low_a7);
      else%High temprature region
        cp(1,:)=R.*(High_a1.*log(T)+(High_a2.*T)+(High_a3.*T.^2)./2+(High_a4.*T.^3)./3+(High_a5.*T.^4)./4+High_a7);
     endif 
    
     %passing the result data
     c_p=cp;
  endfunction

• Code for calculating Molecular weight:

  function mol_wt=mole(species_name)
    
   %defing the masses of diffrent elements
   d=struct('o',15.999,'h',1.00784,'n',14.0067,'c',12.0107,'a',39.948);
   elements={'o','h','n','c','a'};
  
   %handling species name
   species_name=lower(species_name);
   species_name=char(species_name);%converting cell array into string
   mol_wt=0;
   
   %splitting string into corresponding characters
   for i=1:length(species_name)%Iterating between characters of species name
     if(isdigit(species_name(i)))%handling repeated elements
      mol_wt=mol_wt-d.(species_name(i-1));
      mol_wt=mol_wt+(str2num(species_name(i))*d.(species_name(i-1)));
     else
      if(!(any(cell2mat(elements)==species_name(i))))
       break;%ending the loop for characters other than element names
      endif
      mol_wt=mol_wt+d.(species_name(i));
     endif
   endfor
  endfunction