Challenge

Project 1 - Parsing NASA thermodynamic data

KKishan Kumar Singh3 Mar 2022

AIM: To write code in MATLAB to parse NASA thermodynamic data file and then calculate the thermodynamic properties of various species.

OBJECTIVE:

Write a function that extracts the 14 coefficients and calculates the enthalpy, entropy and specific heats for all the species in the ‘THERMO.dat’ file from the given formulae.

Calculate the molecular weight of each species and display it in command window.
Plot the cp, Enthalpy and Entropy for the local temperature range specific for each species.
Save the plots as images with appropriate names and dump them in separate folders for each species.

THEORY:
Data Parsing:

Data parsing is a process of extracting data from the file and use that data for further calculation, study or making important conclusions.

NASA Thermodynamic Data file:

‘THERMO.dat’ file is a data file containing 14 coefficients for 53 different elements given by NASA. These coefficients are used to calculate the specific heat, enthalpy and entropy for a particular species using the given formula.

where,

R = universal gas constant

T = Temperature

Cp = specific heat(KJ)

S = Entropy(KJ/mol-K)

H = Enthalpy(KJ/mol)

a(i) = coefficients where i = 1 to 14

MATLAB Code:

clear all
close all
clc

% getting the data file
f1 = fopen('THERMO.dat','r');
fgetl(f1)

% Reading the header information
A = fgetl(f1);
A = strsplit(A,' ');
global_low_temp = str2num(A{2});
global_mid_temp = str2num(A{3});
global_high_temp = str2num(A{4});

% skipping next three lines
for i = 1:3
    fgetl(f1);
end

% reading the species
for i = 1:53
    header = fgetl(f1);
speciesheader = strsplit(header,' ');
species_name = speciesheader{1};

t1 = str2double(speciesheader{6});
t2 = str2double(speciesheader{7});
t3 = str2double(speciesheader{8});

% getting first line coefficients(a1-a5)
line_1 = fgetl(f1);

a = strfind(line_1,'E');
a1 = str2double(line_1(1:a(1)+3));
a2 = str2double(line_1(a(1)+4:a(2)+3));
a3 = str2double(line_1(a(2)+4:a(3)+3));
a4 = str2double(line_1(a(3)+4:a(4)+3));
a5 = str2double(line_1(a(4)+4:a(5)+3));

% getting second line coefficients(a6 - a10)
 line_2 = fgetl(f1);

 a_1 = strfind(line_2,'E');
 a6 = str2double(line_2(1:a_1(1)+3));
 a7 = str2double(line_2(a_1(1)+4:a_1(2)+3));
 a8 = str2double(line_2(a_1(2)+4:a_1(3)+3));
 a9 = str2double(line_2(a_1(3)+4:a_1(4)+3));
 a10 = str2double(line_2(a_1(4)+4:a_1(5)+3));

% Getting third line coefficients( a11 - a14)
line_3 = fgetl(f1);
a_2 = strfind(line_3,'E');
a11 = str2double(line_3(1:a_2(1)+3));
a12 = str2double(line_3(a_2(1)+4:a_1(2)+3));
a13 = str2double(line_3(a_2(2)+4:a_1(3)+3));
a14 = str2double(line_3(a_2(3)+4:a_1(4)+3));

% Creating folder
mkdir(['C:\Users\dell 1\Desktop\fileparsing\',species_name]);

T = linspace(t1,t3,1000);
R = 8.314;

% to get array of specific heat, enthalpy and entropy
 for k = 1:length(T)

     % to compare species temperature to assign the coefficients
     %a1-a7(high temperature coefficients), a8-a14(low temperature
     %coefficients)
     if T(k)>t2

    % high temperature coefficients

    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
         %low temperature coefficients
         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

 % plotting the graphs

 figure(1)
 plot(T,cp)
 grid on
 title(species_name)
 xlabel('temperature')
 ylabel('Specific Heat')

 figure(2)
 plot(T,H)
 grid on
 title(species_name)
 xlabel('temperature')
 ylabel('Enthalpy')

 figure(3)
 plot(T,S)
 grid on
 title(species_name)
 xlabel('temperature')
 ylabel('Entropy')

 % changing the directory and saving the file
 saving = (['C:\Users\dell 1\Desktop\fileparsing\',species_name]);
 cd(saving);
 saveas(1,'specific heat','jpg');
 saveas(2,'enthalpy','jpg');
 saveas(3,'entropy','jpg');
 
 %molecular mass calculation
 species = species_name;
 elements = ['H','C','O','N','AR'];
 atomic_weight = [1.008 12.011 15.999 14.007 39.948];
 mol_mass = 0;
 for i=1:length(species)
     for m=1:length(elements)
         if strcmpi(species(i),elements(m))
             mol_mass = mol_mass+atomic_weight(m);
             position=m;
         end
     end
 end
 n = str2double(species(i));
 if n>1
     mol_mass = mol_mass + elements(position)*(n-1);
 end
 fprintf('Molecular Weight of %s:%f u\n',species,mol_mass)
end
fclose(f1);

Explanation and steps to program:

We have to open THERMO.dat file and read thgis file using fopen command
Using fgetl command we read the lines and split temperatutre data using strsplit command
Then convert the string into number by str2num command to find low, mid and high temperature
Now we run loop to locate all 53 species using fgetl command
In order to read the coefficient in data file we will first find the E stringusing strfind command to find before and after numbers of coefficients then we will find remaining 14 coefficients and convert them into strings
We create folder to store the plots by using mkdir command
Using if and else loop we assign high and low temperature to the calculation of properties of species in the given formula
We plot the graphs of specific heat, enthalpy and entropy vs temperature and label them respective to their axes.
There are basic 5 elements by which all 53 species are formed, so we made a array of that elements and array of there respective atomic weight.
Now we run for and if loop to calculate the molecular mass of the species
Using fprintf command we display the molecular mass of all 53 species.