Project 1 - Parsing NASA thermodynamic data

Parsing NASA thermodynamic data

Aim: To write the program that parses the given NASA thermodynamic data file in the MATLAB.

Objective:

1. To write a function that extracts the 14 co-efficients and calculates the enthalpy, entropy and specific heats for all the species in the data file.
2. To calculate the molecular weight of each species.
3. To plot the Cp, Enthalpy and Entropy for the local temperature range.

Theory:

What is file parsing?

A. To break down the file into components parts so that it's syntax can be analysed and categorised.

Why do we parse file?

A. A data parser helps us turn unstructured data/un-readable data into structured data.

NASA thermo.dat file:

Nasa's polynomial for enthaly(H),entropy(S) and specific heat(Cp):

The red box in the above image is the coefficients. There are total 14 coefficients and The FIRST 7 coefficients are HIGH-temperature coefficients and the SECOND 7 coefficients are LOW-temperature coefficients.

Program:

clear all
close all
clc

% opening the THERMO file 
f1 = fopen('THERMO.dat','r')
% The first five lines in the above file are comments
% To eliminate we execute the first five lines 
for i=1:5
fgetl(f1)
end

% Since there are 53 species
% Executing the loop for 53 times
ct=0;
for i=1:53


line_1=fgetl(f1);
line_2=fgetl(f1);
line_3=fgetl(f1);
line_4=fgetl(f1);


A = strsplit(line_1,' ')
sp_name=A{1}

%for line_2
e=findstr(line_2,'E');
A1 = str2num(line_2(1:e(1)+3))
A2 = str2num(line_2(e(1)+4:e(2)+3))
A3 = str2num(line_2(e(2)+4:e(3)+3))
A4 = str2num(line_2(e(3)+4:e(4)+3))
A5 = str2num(line_2(e(4)+4:e(5)+3))
%for line_3
e=findstr(line_3,'E');
A6 = str2num(line_3(1:e(1)+3))
A7 = str2num(line_3(e(1)+4:e(2)+3))
A8 = str2num(line_3(e(2)+4:e(3)+3))
A9 = str2num(line_3(e(3)+4:e(4)+3))
A10 = str2num(line_3(e(4)+4:e(5)+3))
%for line_4
e=findstr(line_4,'E');
A11 = str2num(line_4(1:e(1)+3))
A12 = str2num(line_4(e(1)+4:e(2)+3))
A13 = str2num(line_4(e(2)+4:e(3)+3))
A14 = str2num(line_4(e(3)+4:e(4)+3))

g=strsplit(line_1,' ');
len=length(g); 
    local_min_temp=str2num(g{len-3})
    local_max_temp=str2num(g{len-2})
    local_mid_temp=str2num(g{len-1})

% R is the gas constant
R=8.3145;

temp = linspace(local_min_temp,local_max_temp,1000)

for i=1:length(temp)

if temp(i)>local_mid_temp
    cp(i)=(A1+(A2*temp(i))+(A3*(temp(i)^2))+(A4*(temp(i)^3))+(A5*(temp(i)^4)))*R;
    h(i)=(A1+(A2*(temp(i)/2))+((A3*(temp(i)^2))/3)+((A4*(temp(i)^3))/4)+((A5*(temp(i)^4))/5)+(A6/temp(i)))*R*temp(i);
    s(i)=((A1*(log(temp(i))))+(A2*temp(i))+((A3*(temp(i)^2))/2)+((A4*(temp(i)^3))/3)+((A5*(temp(i)^4))/4)+A7)*R;
else
    cp(i)=(A8+(A9*temp(i))+(A10*(temp(i)^2))+(A11*(temp(i)^3))+(A12*(temp(i)^4)))*R;
    h(i)=(A8+(A9*(temp(i)/2))+((A10*(temp(i)^2))/3)+((A11*(temp(i)^3))/4)+((A12*(temp(i)^4))/5)+(A13/temp(i)))*R*temp(i);
    s(i)=((A8*(log(temp(i))))+(A9*temp(i))+((A10*(temp(i)^2))/2)+((A11*(temp(i)^3))/3)+((A12*(temp(i)^4))/4)+A14)*R;
end
end
% creating the folder to store the plots
folder = pwd;
mkdir(['C:\Users\Dell\Documents\MATLAB\NASA\',sp_name]);
%directing the plots towards newly created folder using cd command
cd(['C:\Users\Dell\Documents\MATLAB\NASA\',sp_name]);

Mol_wt= molecular_weight(sp_name);
M_M = sprintf('Molecular Mass of %s = %f',sp_name,Mol_wt)


    figure(1)
    plot(temp,cp);
    title('Temp vs Cp');
    xlabel('Temperature(K)');
    ylabel('Specific Heat(KJ/Kmol-K)');
    saveas(1,'Temp vs Cp.png')

    figure(2)
    plot(temp,h);
    title('Temp vs h');
    xlabel('Temperature(K)');
    ylabel('Enthalpy(J)');
    saveas(2,'Temp vs h.png')

    figure(3)
    plot(temp,s);
    title('Temp vs s');
    xlabel('Temperature(K)');
    ylabel('Entropy(J/K)');
    saveas(3,'Temp vs s.png')
cd(folder)
ct = ct+1;

end
% To close the thermo file using fclose command
fclose(f1);

Function for calculating molecular weigth:

function [M] = molecular_weight(sp_name)

Atomic_mass = [15.999,1.008,12.011,14.007,39.948];
Elements = ['O','H','C','N','A'];


Mol_wt = 0;
for i = 1:length(sp_name)
    for j = 1:length(Elements)
        if strcmpi(sp_name(i),Elements(j))
            Mol_wt = Mol_wt+Atomic_mass(j);
            z = j;
 
        end
    end
    var = str2double(sp_name(i));
     if (var>1)
   
         Mol_wt = Mol_wt+(Atomic_mass(z)*(var-1));
    
     end   

end
M = Mol_wt;
end

Procedure:

1. To open the NASA thermodynamic file in matlab use fopen command.
2. The file has comments for the first five lines and from the next line the actual data starts.
3. Executing the first five lines in order to eliminate comments from the data file.
4. Assigning the next four lines to line_1,line_2,line_3,line_4 respectively.
5. The first word of line_1 has the species name. Now in order to get the first word assigned to the species name, We first split the line_1 using 'strsplit' command.
6. Now assigning each co-efficient in line_2,line_3 and line_4 to a separate variable with respect to the letter 'E'.
7. And converting 'co_efficient' to numbers from string, using 'str2num' command.
8. Using if-else statement to place The FIRST 7 coefficients as HIGH-temperature coefficients and the SECOND 7 coefficients as LOW-temperature coefficients.
9. The temperature (temp) is divided into 1000 equal spaces between minimum temperature and maximum temperature using the linspace command.
10. Now creating a new directory and changing the path towards this directory using 'mkdir' and 'cd' command.
11. Plotting three graph in three separate figures. And saving the plots using 'saveas' command.
12. Lastly closing the thermo.dat file using 'fclose' command.

output:

Plots for O2:

Plots for N2:

Plots for CO2:

Molecular weight in the Command window:

Conclusion:

Therefore, we have successfully parsed the given NASA thermodynamic data file and plotted the graphs of specific heat(Cp), enthalpy(H) and entropy(S) for the respective species name.