PARSING NASA THERMODYNAMIC DATA

AIM: TO PARSE THE THERMODYNAMIC DATA FROM NASA USING MATLAB

THEORY: The official record of thermodynamic values at different temperatures has been stored by NASA in the form of polynomials with specified constants ranging from one to fourteen for various species. In order to quantify the values, the polynomials can be solved with defined temperature values in accordance with our requirements.

The term ‘parsing’ refers to MATLAB reading an m-file (script or function) and translating it into an internal code that it stores in memory. It is this ‘parsed’ file in memory that is actually run when you execute the code.

GOVERNING EQUATIONS:

· SPECIFIC HEAT –

C_P/R=a1+a2×T+a3×T^2+a4×T^3+a5×T^4CP​/R=a1+a2×T+a3×T2+a4×T3+a5×T4

· ENTHALPY –

H/RT= a1+a2×T/2+a3×T^2/3+a4×T^3/4+a5×T^4/5+a6/TH/RT=a1+a2×T/2+a3×T2/3+a4×T3/4+a5×T4/5+a6/T

· ENTROPY –

S/R=a1×logT+a2×T+a3×T^2/2+a4×T^3/3+a5×T^4/4+a7S/R=a1×lnT+a2×T+a3×T2/2+a4×T3/3+a5×T4/4+a7

where,

C_P = Specific Heat

H = Enthalpy

S = Entropy

R = Universal Gas Constant (8.314 J/mol.K)

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 every species and displaying in command window.
3. To plot specific heat, enthalpy and entropy with temperature range distributed from global high temperature to global low temperature.
4. To create a separate folder for all the plots and saving them in ‘.png’ format.

FUNCTION PROGRAM 1: Calculating thermodynamic properties (specific heat, enthalpy, entropy)

function [cp, h, s] = coeff(a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12,a13,a14,T)
 
R = 8.314;
for j = 1:length(T)
    if T(j) < 300
        
        cp = (a1 + a2.*T + a3.*T.^2 + a4.*T.^3 + a5.*T.^4).*R;
        h = (a1 + (a2.*T)./2 + (a3.*T.^2)./3 + (a4.*T.^3)./4 + (a5.*T.^4)./5 + (a6./T)).*R.*T;
        s = (a1.*log(T) + a2.*T + (a3.*T.^2)./2 + (a4.*T.^3)./3 + (a5.*T.^4)./4 + a7).*R;
        
    else
        
        cp = (a8 + a9.*T + a10.*T.^2 + a11.*T.^3 + a12.*T.^4).*R;
        h = (a8 + (a9.*T)./2 + (a10.*T.^2)./3 + (a11.*T.^3)./4 + (a12.*T.^4)./5 + (a13./T)).*R.*T;
        s = (a8.*log(T) + a9.*T + (a10.*T.^2)./2 + (a11.*T.^3)./3 + (a12.*T.^4)./4 + a14).*R;
        
    end
end
 
end

FUNCTION PROGRAM 2: Calculating molecular weight of species mentioned in data file

function [molecular_weight] = mole_wt(species_name)
 
SPECIES = upper(species_name)
constituents = {'H','C','N','O','A'};
atomic_weight = [1 12 14 16 40];
 
molecular_weight = 0;
for i = 1:length(SPECIES)
    for j = 1:length(constituents)
        if strcmp(SPECIES(i),constituents(j))
            molecular_weight = molecular_weight + atomic_weight(j);
            u = j;
        end
    end
    
    n = str2double(SPECIES(i));
    if n > 1
        molecular_weight = molecular_weight + atomic_weight(u)*(n-1);
    end
end
fprintf('molecular_weight of %s:- ',species_name)
fprintf('%d',molecular_weight)
fprintf(' ')
fprintf('amu')
fprintf('\n')
end

MAIN PROGRAM:

clear all
close all
clc
 
% Reading the thermodynamic data file
f1 = fopen('THERMO.dat','r')
file_name = fgetl(f1);
t_line = fgetl(f1);
A = strsplit(t_line,' ');
 
% Defining the temperatures extracted from data file
global_low_temp = str2double(A{2});
global_mid_temp = str2double(A{3});
global_high_temp = str2double(A{4});
 
for i = (1:3)
    comments = fgetl(f1);
end
 
for i = 1:53
    
    % Extracting species name
    species = fgetl(f1);
    species_name = species(1:6);
    
    % Extracting coefficients from first line 
    line_1 = fgetl(f1);
    l1 = strfind(line_1,'E');
    a1 = str2double(line_1(1:(l1(1)+3)));
    a2 = str2double(line_1((l1(1)+4):(l1(2)+3)));
    a3 = str2double(line_1((l1(2)+4):(l1(3)+3)));
    a4 = str2double(line_1((l1(3)+4):(l1(4)+3)));
    a5 = str2double(line_1((l1(4)+4):(l1(5)+3)));
    
    % Extracting coefficients from second line 
    line_2 = fgetl(f1);
    l2 = strfind(line_2,'E');
    a6 = str2double(line_2(1:(l2(1)+3)));
    a7 = str2double(line_2((l2(1)+4):(l2(2)+3)));
    a8 = str2double(line_2((l2(2)+4):(l2(3)+3)));
    a9 = str2double(line_2((l2(3)+4):(l2(4)+3)));
    a10 = str2double(line_2((l2(4)+4):(l2(5)+3)));
    
    % Extracting coefficients from third line 
    line_3 = fgetl(f1);
    l3 = strfind(line_3,'E');
    a11 = str2double(line_3(1:(l3(1)+3)));
    a12 = str2double(line_3((l3(1)+4):(l3(2)+3)));
    a13 = str2double(line_3((l3(2)+4):(l3(3)+3)));
    a14 = str2double(line_3((l3(3)+4):(l3(4)+3)));
    
    % Creating a folder 'SPECIES' to save thermodynamic plots of species
    mkdir(['D:\MOOC\SKILL-LYNC\MATLAB Practice Programs\Challenges\7 - PROJECT\SPECIES\', species_name]);
    
    T = linspace(global_low_temp, global_high_temp, 500);
    
    % calling the thermodynamic equations function
    [cp, h, s] = coeff(a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12,a13,a14,T);
    
    % Plotting
    % Plot between Temperature and Specific Heat
    figure(1)
    plot(T,cp,'linewidth',3,'color','b')
    title (species_name)
    xlabel('TEMPERATURE')
    ylabel('SPECIFIC HEAT')
    
    % Plot between Temperature and Enthalpy
    figure(2)
    plot(T,h,'linewidth',3,'color','g')
    title(species_name)
    xlabel('TEMPERATURE')
    ylabel('ENTHALPY')
    
    % Plot between Temperature and Entropy
    figure(3)
    plot(T,s,'linewidth',3,'color','c')
    title(species_name)
    xlabel('TEMPERATURE')
    ylabel('ENTROPY')
    
   
    directory = (['D:\MOOC\SKILL-LYNC\MATLAB Practice Programs\Challenges\7 - PROJECT\SPECIES\',species_name]);
    cd(directory)
    
    % Saving plots
    saveas(1,'specific_heat.png')
    saveas(2,'enthalpy.png')
    saveas(3,'entropy.png')
    
    % Changing directory for calculating molecular weight
    cd('D:\MOOC\SKILL-LYNC\MATLAB Practice Programs')
    molecular_weight = mole_wt(species_name);
    
end
fclose(f1)

EXPLANATION OF PROGRAM:

· Initially, a code is written to read the desired data file and values are assigned. Here, comments and other data is read using respective commands.

· The coefficient values are determined and allotted to a constant.

· A new folder with the name ‘SPECIES’ is created to desired location. The coefficient function is called and plotting of graphs is carried out.

· Plots are saved in the specified folder and the process of determining molecular weight is carried out.

· The molecular weight function is called and the values are printed in the command window.

OUTPUT (Command Window Listing Molecular Weight of Species):

OUTPUT (Location of SPECIES Folder):

PLOTS:

· For O₂: -

· For N₂: -

· For CO₂: -

CONCLUSION: The parsing of thermodynamic data file by NASA is done using certain commands in MATLAB. Also, the plots of thermodynamic properties v/s temperature are saved in a separate folder created by writing a specific code. Moreover, a function has been coded to calculate the molecular weight of the species mentioned in the given data file. From the above program, it can be exerted that new folders with desired information can be created and the files can be easily saved for further use.

REFERENCES:

https://en.wikipedia.org/wiki/Parsing

https://in.mathworks.com/help/matlab/matlab_prog/parse-function-inputs.html

https://in.mathworks.com/help/matlab/ref/inputparser.html