Project 1 - Parsing NASA thermodynamic data

clc
clear all
close all

% Opening 'Thermo.dat' file in read mode using fopen function

ff1 = fopen('Thermo.dat','r')

% Title
l1 = fgetl(ff1);

% Global temperature values
l2 = fgetl(ff1)
A = strsplit(l2,' ');
Global_min_Temp = str2num(A{2});
Global_mid_Temp = str2num(A{3});
Global_max_Temp = str2num(A{4});

% Ignoring next three comments
l3 = fgetl(ff1);
l4 = fgetl(ff1);
l5 = fgetl(ff1);

% Loop for covering all 53 species present in data file
for i = 1:53
species = fgetl(ff1);
species_name = species(1:6)

Lin_1 = fgetl(ff1);
L1 = strfind(Lin_1,'E');
Cof1 = str2num(Lin_1(1:(L1(1)+3)));
Cof2 = str2num(Lin_1((L1(1)+4):(L1(2)+3)));
Cof3 = str2num(Lin_1((L1(2)+4):(L1(3)+3)));
Cof4 = str2num(Lin_1((L1(3)+4):(L1(4)+3)));
Cof5 = str2num(Lin_1((L1(4)+4):(L1(5)+3)));

Line_2 = fgetl(ff1);
L2 = strfind(Line_2,'E');
Cof6 = str2num(Line_2(1:(L2(1)+3)));
Cof7 = str2num(Line_2((L2(1)+4):(L2(2)+3)));
Cof8 = str2num(Line_2((L2(2)+4):(L2(3)+3)));
Cof9 = str2num(Line_2((L2(3)+4):(L2(4)+3)));
Cof10 = str2num(Line_2((L2(4)+4):(L2(5)+3)));

Line_3 = fgetl(ff1);
L3 = strfind(Line_3,'E');
Cof11 = str2num(Line_3(1:(L3(1)+3)));
Cof12 = str2num(Line_3((L3(1)+4):(L3(2)+3)));
Cof13 = str2num(Line_3((L3(2)+4):(L3(3)+3)));
Cof14 = str2num(Line_3((L3(3)+4):(L3(4)+3)));

% Temperature Range assumed
Temp = linspace(300,5000,500);

% Universal gas constant
R = 8.314;

% Calculation using given formula
for j = 1:length(Temp)
if Temp(j)>1000
Cp = (Cof1+Cof2.*Temp+Cof3.*Temp.^2+Cof4.*Temp.^3+Cof5.*Temp.^4).*R;
H = (Cof1+(Cof2.*Temp)./2+(Cof3.*Temp.^2)/3+(Cof4.*Temp.^3)/4+(Cof5.*Temp.^4/5)+Cof6./Temp).*Temp.*R;
S = (Cof1*log(Temp)+Cof2.*Temp+(Cof3.*Temp.^2)/2+(Cof4.*Temp.^3)/3+(Cof5.*Temp.^4)/4+Cof7).*R;
else
Cp = (Cof8+Cof9.*Temp+Cof10.*Temp.^2+Cof11.*Temp.^3+Cof12.*Temp.^4).*R;
H = (Cof8+(Cof9.*Temp)/2+(Cof10.*Temp.^2)/3+(Cof11.*Temp.^3)/4+(Cof12.*Temp.^4/5)+Cof13./Temp).*Temp.*R;
S = (Cof8.*log(Temp)+Cof9.*Temp+(Cof10.*Temp.^2)/2+(Cof11.*Temp.^3)/3+(Cof12.*Temp.^4)/4+Cof14).*R;
end
end

current_dir = pwd; % 'current_dir' variable contains the path of current directory
mkdir(species_name); % new directory is made using mkdir function with species name
cd(species_name); % Moving to new species directory

%Plotting all graph

% Temp vs Entropy
figure(1)
plot(Temp,S,'linewidth',3,'color','b')
title(species_name)
xlabel('Temperature')
ylabel('Entropy')
grid on
%Temp vs Enthalpy
figure(2)
plot(Temp,H,'linewidth',3,'color','g')
title(species_name)
xlabel('Temperature')
ylabel('Enthalpy')
grid on
% Temp vs Specific heat
figure(3)
plot(Temp,Cp,'linewidth',3,'color','r')
title(species_name)
xlabel('Temperature')
ylabel('Specific heat')
grid on
%Saving the plot generated in species directory

saveas(figure(1), 'Entropy.jpg');
saveas(figure(2), 'Enthalpy.jpg');
saveas(figure(3), 'Specific heat.jpg');
cd(current_dir);

Mass = molecular_mass(species_name) % Function for calculating molecular_mass

end

fclose(ff1) % Closing the Thermo.dat file

Plot of Enthalpy, Entropy, and Specific heat for O₂, N₂ and CO₂:-

Folder where these plots are saved

Molecular Weight of Species

Explanation of Code

The file ‘Thermo.dat’ is open using in-built MatLab function ‘fopen’ in read mode. This thermo.dat file is assigned to a variable ff1. The fgetl function is used to read the file line by line. Firstly the title of this file is assigned to l1 variable. The second line has global maximum, minimum, mean temperature value that converted into a number using str2num command. The next three consecutive lines that contain comments are not required in our program, hence these lines are skipped. An array of five hundred temperature values range between 300 degrees to 5000 degrees is created using linspace command. The value of the universal gas constant is given as input in the code. ‘For’ loops are used to read the data of all species from the given file. The fgetl command is used to read file line by line. The coefficients are converted into the numeric form using str2num command and are stored in variables named Cof1 to Cof12. The first seven coefficients are high-temperature value and the next seven are low-temperature values. Now, using ‘if-else’ statement the assumed temperature range is divided into two parts i.e if temperature values are less than 1000 degree then the expression of entropy, enthalpy and specific heat is calculated based on low-temperature coefficient value, else are calculated based on high-temperature value coefficient for each species present in ‘thermo.dat’ file. A variable is created to store the path of the current working directory using pwd command. The command mkdir is used to create the directory for each species with their names. Now, using the cd command current directory is changed to a new-formed directory with the name of species. In this new directory, for each species, their variations in specific heat, enthalpy and entropy with temperature are plotted respectively and save using save as command. A separate molecular_species function is coded to get mass of each species.

Reference: NIST Chemistry WebBook