Parsing NASA Thermodynamic Data using MATLAB

AIM :

To Parse the Thermodynamic Data from NASA using MATLAB

THEORY :

Data Parsing

Data parsing is a process of extracting data from a file and use that data for further calculation or study or making some important conclusions and how that information can be used in a computer program.

NASA Thermodynamic Data File

'THERMO.dat' file is a data file containing 14 coefficients for 53 different elements given by NASA. These coefficients are utilized to calculate the specific heat, enthalpy, and entropy for a particular element. Each element has its own range of local temperature.

GOVERNING EQUATIONS :

• Specific Heat

`C_P⁄R =a1+a2 ×T+a3 × T^2+ a4 × T^3+ a5 ×T^4`

• Enthalpy

`H⁄RT =a1+a2 × T⁄2+ a3 × T^2⁄3+ a4 × T^3⁄4+ a5 × T^4⁄5+ a6⁄T`

• Entropy

`S⁄R =a1 × ln⁡T+ a2 ×T+a3 × T^2⁄2+ a4 × T^3⁄3+ a5 × T^4⁄4+ a7`

where,

C_P = Specific Heat

H = Enthalpy

S = Entropy

R = Universal Gas Constant

T = Temperature

* The First 7 Coefficients are High Temperature Coefficients and the Second 7 Coefficients are Low Temperature Coefficients.

OBJECTIVE :

1. To write a function extracting the 14 coefficients from the data file and calculating the specific heat, enthalpy and entropy of all species.
2. To calculate molecular weight of each species and displaying in command window.
3. To plot specific heat, enthalpy and entropy for the local temperature range (low temperature : high temperature) specific for each species.
4. To create a separate folder for all the plots and saving them in ‘.png’ format.

MAIN CODE :

% Program to Parse NASA's Thermodynamic Data

close all
clear
clc

% Universal Gas Constant (R)
R = 8.314;

% Loading Data File
File = fopen('THERMO.dat','r');

% Reading 1st Line
fgetl(File);

% Defining Temperature Values
t_line = fgetl(File);
Global_Temp = strsplit(t_line,' ');
Global_Low_Temp = str2double(Global_Temp{2});
Global_Mid_Temp = str2double(Global_Temp{3});
Global_High_Temp = str2double(Global_Temp{4});

% For Skipping Unwanted Lines
for i = 1:3
    comments = fgetl(File);
end

% Creating a New Folder
mkdir('F:\MATLAB\Program\Parsing NASA Thermodynamic Data','SPECIES')

% To Iterate through all 53 Elements

for i = 1:53

    % Extracting Species Name
    line1 = fgetl(File);
    Species = Get_Species(line1);
    
    % Calculating Molecular Weight
    Molecular_Weight = Molecular_weight(Species);
    fprintf('\nMolecular Weight of %s is : %d',Species,Molecular_Weight)
    
    % Calculating Local Temperature Range
    Local_Temp_Range = Get_Local_Temp_Range(line1);
    
    % Calculating Coefficients Data
    c(1:5) = Coefficients(fgetl(File));
    c(6:10) = Coefficients(fgetl(File));
    c(11:14) = Coefficients(fgetl(File));

    % Temperature
    T = linspace(Local_Temp_Range(1),Local_Temp_Range(3),500);
    
    % Specific Heat ( Cp )
    Cp = Specific_Heat(c, Local_Temp_Range, T, R);

    % Enthalpy ( H )
    H = Enthalpy(c, Local_Temp_Range, T, R);

    % Entropy ( S )
    S = Entropy(c, Local_Temp_Range, T, R);

    
    % Plotting and Saving
    
    % Creating New Folder with Species Name    
    cd('SPECIES')
    mkdir(Species);
    
    % Open that Folder
    cd(Species)
    
    % Plotting Temperature VS Specific Heat
    figure(1)
    plot(T,Cp,'linewidth',2,'color','k')
    xlabel('Temperature [K]');
    ylabel('Specific Heat [KJ/Kg-K]');
    title(sprintf('Temperature VS Specific Heat Plot for %s',Species))
    grid on
    
    % Saving Plots
    saveas(figure(1), 'Specific Heat.png')
    
    % Plotting Temperature VS Enthalpy
    figure(2)
    plot(T,H,'linewidth',2,'color','r')
    xlabel('Temperature [K]');
    ylabel('Enthalpy [KJ/Kg]');
    title(sprintf('Temperature VS Enthalpy Plot for %s',Species))
    grid on
    
    % Saving Plots
    saveas(figure(2), 'Enthalpy.png')
    
    % Plotting Temperature VS Entropy
    figure(3)
    plot(T,S,'linewidth',2,'color','g')
    xlabel('Temperature [K]');
    ylabel('Entropy [KJ/Kg-K]');
    title(sprintf('Temperature VS Entropy Plot for %s',Species))
    grid on

    % Saving Plots
    saveas(figure(3), 'Entropy.png')
    
    
    % Goes Back to Parent Folder
    cd('F:\MATLAB\Program\Parsing NASA Thermodynamic Data')
   
end

Explanation

Step 1 : Defined the input value of Universal Gas Constant (R).

Step 2 : Then, "THERMO.dat" file was opened using "fopen" command. And the lines of this file were read and extracted by using the "fgetl" command.

Step 3 : Because the next three lines in the file do not have any information regarding the code. The lines were skipped. And then, created a new folder called "SPECIES" .

Step 4 : Then as there are 53 species so "for" loop was run "53" times. Now before solving the main code, we have to create some functions.

Function for Calculating Species :

function Species = Get_Species(line)

split = strsplit(line,' ');
Species = (split{1});

end

Step 5 : So firstly, we created a function called "Get_Species". Then, we called the function in our main code to getting species name.

Function for Calculating Molecular Weight :

function molecular_weight = Molecular_weight(species)

molecular_weight = 0;
Atoms = ['O', 'H', 'N', 'C', 'S', 'A'];
Atomic_weights = [16, 1, 14, 12, 32, 40];

    for i = 1 : length(species)
        for j = 1 : length(Atoms)
        
            if strcmp(species(i), Atoms(j))
                molecular_weight = molecular_weight + Atomic_weights(j);
                w = j;
            
            end
        end
    
        z = str2double(species(i));
            if z > 1
            molecular_weight = molecular_weight + Atomic_weights(w) * (z-1);
            end
        
    end
end

Step 6 : Then, we created a function called "Molecular_weight". And then, we called the function in our main code to solve the molecular weight.

Function for Calculating Local Temperature Range :

function temp = Get_Local_Temp_Range(line)

split = strsplit(line, ' ');
l = length(split);
low_temp = str2double(split{l-3});
mid_temp = str2double(split{l-1});
high_temp = str2double(split{l-2});

temp = [low_temp mid_temp high_temp];

end

Step 7 : And then, we created a function called "Get_Local_Temp_Range" for getting local temperature range.

Function for Calculating Coefficients Data :

function c = Coefficients(line)

E = strfind(line,'E');
c(1) = str2double(line(1 : E(1)+3));
    
    for i = 1 : length(E)-1
        t = str2double(line(E(i)+4 : E(i+1)+3));
        c(i+1) = t;
    end

end

Step 8 : Then, we created a function called "Coefficients" for calculating the coefficients data.

Function for Calculating Specific Heat :

function Cp = Specific_Heat(c, local_temp_range, T, R)

    for i = 1 : length(T)
        if T(i) <= local_temp_range(2)
           Cp(i) = R*(c(8) + c(9)*T(i) + c(10)*T(i)^2 + c(11)*T(i)^3 + c(12)*T(i)^4);
        else
           Cp(i) = R*(c(1) + c(2)*T(i) + c(3)*T(i)^2 + c(4)*T(i)^3 + c(5)*T(i)^4);
            
        end     
    end
end

Step 9 : Now, we created a function called "Specific_Heat". Then, we called the function in our main code to solve the specific heat.

Function for Calculating Enthalpy :

function H = Enthalpy(c, local_temp_range, T, R)

    for i = 1 : length(T)
        
        if T(i) <= local_temp_range(2)
           H(i) = R*T(i)*(c(8) + c(9)*T(i)/2 + c(10)*(T(i)^2)/3 + c(11)*(T(i)^3)/4 + c(12)*(T(i)^4)/5 + c(13)/T(i));
        else
           H(i) = R*T(i)*(c(1) + c(2)*T(i)/2 + c(3)*(T(i)^2)/3 + c(4)*(T(i)^3)/4 + c(5)*(T(i)^4)/5 + c(6)/T(i));
        end
        
    end
end

Step 10 : Again, we created a function called "Enthalpy". And then, we called the function in our main code to solve the enthalpy.

Function for Calculating Entropy :

function S = Entropy(c, Local_Temp_Range, T, R)

    for i = 1 : length(T)
        
        if T(i) <= Local_Temp_Range(2)
           S(i) = R*(c(8)*log(T(i)) + c(9)*T(i) + c(10)*(T(i)^2)/2 + c(11)*(T(i)^3)/3 + c(12)*(T(i)^4)/4 + c(14));
        else
           S(i) = R*(c(1)*log(T(i)) + c(2)*T(i) + c(3)*(T(i)^2)/2 + c(4)*(T(i)^3)/3 + c(5)*(T(i)^4)/4 + c(7));
        end
        
    end
end

Step 11 : Lastly, we created a function called "Entropy" to solve the entropy.

Step 12 : At the end, we plotted for Temperature VS ( Specific Heat, Enthalpy and Entropy ) respectively for each and every element and saved them in separate folders.

RESULTS :

Workspace Values :

Molecular Weight of Each Species :

Folders that were Created Automatically :

Plots of O2 :

Plots of N2 :

Plots of CO2 :