Project 1 - Parsing NASA thermodynamic data

Aim: To write a code for parsing the NASA thermodynamic data file and then to calculate the thermodynamic properties of various gas species.

Objective: To write a function to extract the higher temperature and lower temperature co-efficients and to calculate the enthalpy,entropy and specific heats for all the species in the NASA thermodynamic file "Thermo.dat". And also to plot the specific heat, enthalpy and entropy for the local temperature range for each species.

File parsing: Parsing a file means reading in a data stream of some sort and building a memory model of the semantic content of that data. 

Formulas:

Specific Heat (Cp) = (a1+(a2.*T_r)+(a3.*(T_r).^2)+(a4.*(T_r).^3)+(a5.*(T_r).^4)).*R

Entropy (S) =  R*(a1.*log(T_r)+(a2.*T_r)+((a3.*(T_r).^2)/2)+((a4.*(T_r).^3)/3)+((a5*(T_r).^4)/4)+a7)

Enthalpy (H) = R*T_r.*(a1+(a2*T_r/2)+(a3*(T_r).^2/3)+((a4*(T_r).^3)/4)+(a5*(T_r).^4)/5+(a6./T_r))

Main Code:

clear all
close all
clc
R = 8.314
f1 = fopen('THERMO.dat','r')
get = fgetl(f1);
 
temp = fgetl(f1);
 
%splitting the terms
s = strsplit(temp);
%converting strings cells into numbers
low_temp = str2num(s{2})
mid_temp = str2num(s{3})
high_temp = str2num(s{4})
% Defining temp range
T_r = linspace(low_temp,high_temp,1000)
 
%for skipping the lines
for i=1:3
    get = fgetl(f1);
   
end
% Getting each species
for j = 1:57
    tline = fgetl(f1);
    A=strsplit(tline,' ');
    species = (A{1});
    
    low_temp = str2num(A{end-3});
    mid_temp = str2num(A{end-2});
    high_temp = str2num(A{end-1});
    
    %getting next line
    tline1 = fgetl(f1); 
    %finding the string E
    a =  strfind(tline1,'E');
    % finding first 7 higher co-efficients
    a1 = tline1(1:a(1)+3);
    a1 = str2num(a1);
    a2 = tline1(a(1)+4:a(2)+3);
    a2 = str2num(a2);
    a3 = tline1(a(2)+4:a(3)+3);
    a3 = str2num(a3);
    a4 = tline1(a(3)+4:a(4)+3);
    a4 = str2num(a4);
    a5 = tline1(a(4)+4:a(5)+3);
    a5 = str2num(a5);
    
    tline2 = fgetl(f1);
    b = strfind(tline2,'E');
    a6 = tline2(1:b(1)+3);
    a6 = str2num(a6);
    a7 = tline2(b(1)+4:b(2)+3);
    a7 = str2num(a7);
    
   % Finding second 7 Lower Co-efficients
   a8 = tline2(b(2)+4:b(3)+3);
   a8 = str2num(a8);
   a9 = tline2(b(3)+4:b(4)+3);
   a9 = str2num(a9);
   a10 = tline2(b(4)+4:b(5)+3);
   a10 = str2num(a10);
   
   tline3 = fgetl(f1);
   c = strfind(tline3,'E');
   a11 = tline3(1:c(1)+3);
   a11 = str2num(a11);
   a12 = tline3(c(1)+4:c(2)+3);
   a12 = str2num(a12);
   a13 = tline3(c(2)+4:c(3)+3);
   a13 = str2num(a13);
   a14 = tline3(c(3)+4:c(4)+3);
   a14 = str2num(a14);
   
   % calculating Specific heat 
   Cp = Specific_heat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,T_r,R,mid_temp);
   
   % calculating Entropy
   S = Entropy(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,T_r,R,mid_temp);
   
   % calculating Enthalpy
   H = Enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,T_r,R,mid_temp);
   
   % calculatiing Molecular weight of the species
   W = Molecular_weight(species);
   
   % writing molecular weight file 
   MW_file = fopen('Molecular Weight.txt','W');
   fprintf(MW_file,'Molecular Weight of %s is %d',species,W);
   fclose(MW_file); % closing the file
   
   %Plotting Cp, H and S with Temperature 
   % Saving in a folder
   cd('E:\Programming Files\Nasa\atomic_species')
   mkdir(species);
   cd(species);
   % Plot 1 Cp vs T
   figure(1)
   plot(T_r,Cp,'linewidth',2,'color','b');
   xlabel('Temperature(K)');
   ylabel('Specific Heat(KJ)');
   title(sprintf('Specific heat vs Temperature range of %s',species));
   grid on 
   saveas(figure(1),'Specific Heat.jpg');
   
   % Plot 2 S vs T
   figure(2)
   plot(T_r,S,'linewidth',2,'color','r');
   xlabel('Temperature(K)');
   ylabel('Entropy(KJ/mol-K');
   title(sprintf('Entropy vs Temperature range of %s', species));
   grid on
   saveas(figure(2),'Entropy.jpg');
   
   % Plot 3 Cp vs T
   figure(3)
   plot(T_r,H,'linewidth',2,'color','g');
   xlabel('Temperature');
   ylabel('Enthalpy(KJ/mol)');
   title(sprintf('Enthalpy vs Temperature range of %s',species));
   grid on
   saveas(figure(3),'Enthalpy.jpg');
   
   cd('E:\Programming Files\Nasa\atomic_species')
   
end

 Procedure:

• At first use clear all, close all and clc to clear all datas in workspace, all plots and figures and clear datas in the command window.
• fgetl command is used to read the THERMO.dat file.
• Using strsplit command we will split the temperatures and by using str2num command we will converting string to number.
• linspace command is used to assign temperature and we will run loop to skip command lines the data file using f getl command inside the loop.
• Then using loop we will run elements in the data file by assigning fgetl command and splitting into cell array.
• Using strfind command we will find 'E' string from the line of the data file and then will find all 14 coefficients which are in strings. And then we will converted into numbers using str2num command.
• Then we will assume first 7 co-efficients as higher temperature and second 7 co-efficients as lower temperature.
• After taking all 14 co-efficients from 'THERMO.dat' file, then we will call all the functions for specific heat, entropy and enthalpy.
• To these functions we will input the values of all co-efficients.
• For molecular weight formula we will open a file named'Molecular Weight.txt' and print the values.
• Then we will create a folder inorder to save the files of all plots of Cp, H and S.
• Using plot command we will plotting all the species of Cp vs T, S vs H and H vs T in the file.
• All plots will be saved in the respective folders.
• Finally using end command we will end the for loop.

Functions :

To find specific heat:

function Cp = Specific_heat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,T_r,R,mid_temp)
 
if (T_r <= mid_temp)
    Cp = (a8+(a9.*T_r)+(a10.*(T_r).^2)+(a11.*(T_r).^3)+(a12.*(T_r).^4)).*R;
else
    Cp = (a1+(a2.*T_r)+(a3.*(T_r).^2)+(a4.*(T_r).^3)+(a5.*(T_r).^4)).*R;
end
end

Procedure :

• Creating a function named specific heat.
• Assigning the values for co-efficients, temperature ,gas constant and mid temperature.
• Using 'if' conditional statement, we will split the temperature ranges to temperatures equal to or below mid temperature as lower temperature co-efficient in the formula.
• 'else' condition is used to specify higher temperature co-efficients.
• Using end command we will end the if statement and function.

To find entropy :

function S = Entropy(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,T_r,R,mid_temp)
 
if (T_r<= mid_temp)
    S = R*(a8.*log(T_r)+(a9.*T_r)+((a10.*(T_r).^2)/2)+((a11.*(T_r).^3)/3)+((a12*(T_r).^4)/4)+a14);
else
    S = R*(a1.*log(T_r)+(a2.*T_r)+((a3.*(T_r).^2)/2)+((a4.*(T_r).^3)/3)+((a5*(T_r).^4)/4)+a7);
end
end

Procedure :

• Creating a function named entropy.
• Assigning  all co-efficient values, temperature, gas constant and mid temperature.
• Using if and else statement, we splitting the temperatures ranges as higher and lower temperature co-efficients.
• End command is used to end the function and if statement.

 

To find enthalpy :

function H = Enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,T_r,R,mid_temp)
 
if (T_r<=mid_temp)
    H = R*T_r.*(a8+((a9*T_r)/2)+((a10*(T_r).^2)/3)+((a11*(T_r).^3)/4)+((a12*(T_r).^4)/5)+(a13./T_r));
else
    H = R*T_r.*(a1+(a2*T_r/2)+(a3*(T_r).^2/3)+((a4*(T_r).^3)/4)+(a5*(T_r).^4)/5+(a6./T_r));
end
end

Procedure :

• Creating a function named enthalpy.
• Assigning values of co-efficients, temperature, gas constant and mid temperature.
• Using if and else statement specifying and splitting the higher and lower temperature co-efficients.
• Then using end command we will end the function and if statement.

To find Molecular weight :

function[W]=Molecular_weight(species)
%Defining atomic name of the species
atomic_name=['H','C','O','N','Ar'];

%Defining atomic masses of main species
atomic_weight=[1.008 12.011 15.999 14.007 39.948];

W=0; % molecular weight starting range
for i=1:length(species) %loop runs to the length of the species
    for j=1:length(atomic_name) %loop runs to the length of the atomic names
        if strcmp(species(i),atomic_name(j)) 
            W=W+atomic_weight(j);
            position=j;
        end
    end
    n=str2num(species);
    if n>1
        W=W+atomic_weight(position)*(n-1);
    end 
end

fprintf('Molecular Weight of %s :- ',species);
fprintf('%f',W);
disp(' ')
end

Procedure :

• Creating a function for molecular weight.
• Assigning the species input to the function.
• Then defining the main elements in the 53 species in an array.
• We will create array for atomic weight.
• Starting range for the molecular weight is assigned as zero.
• Then we will run a for loop for running to the length of the species and a nested loop is created to run to the length of the string atomic name.
• Using if condition we will use a command 'strcmp' to compare the species and atomic name strings to calculate molecular mass  if by comparison both string found same then we will assign its molecular weight.
• Then we will convert the string into number using str2num command and then will assign to n.
• Using if statement we will find whether the species contains more than one element if there are more then 1 elements that is n>1 then we will increment the atomic weight by the multiplication of position and n-1 to the atomic weight array.
• Then we will print the molecular weight using 'fprintf' command and display it using 'disp' command.

Results :

Plots of all the species listed in the "THERMO.dat" file is being saved in a file named atomic_species. And from those species the plots of O2, N2 and CO2 is attached here with the results and also the screenshot of the window where all files are saved is also attached.

Plots of O2 species:

Plots of N2 species :

Plots of CO2 species :