Challenge

Project 1 - Parsing NASA thermodynamic data

PParth Tulsyan20 Jan 2021

AIM: 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. The formulae are shown below.

Here R is the universal gas constant, T is the temeprature

1. function for calculating specific heat,entropy,enthalpy:-

function[Cp,H,S] = property(A1,A2,A3,A4,A5,A6,A7,a1,a2,a3,a4,a5,a6,a7,T,gmt)
%here gmt = global mid temperature
R = 8.314;
    if T <= gmt
        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)).*(T.*R);
        S = ((A1.*log(T))+(A2.*T)+((A3.*T.^2)./2)+((A4.*T.^3)./3)+((A5.*T.^4)./4)+A7)*R;
    else
        
        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)).*(T.*R);
        S = ((a1.*log(T))+(a2.*T)+((a3.*T.^2)./2)+((a4.*T.^3)./3)+((a5.*T.^4)./4)+a7)*R;
    end
end

for calculating the specific heat(Cp),entropy(H) and enthalpy(S) we have created a function code.
as we have different coefficients for different temperature ranges, we have used 'if else' syntax which changes the flow of code depending on the temperature.

2. function for calculating molecular weight:-

function [MW] = molecular_weight(species)
atoms = {'H','C','N','O','A'};
fprintf('Molecular Weight of ');
fprintf(species);
fprintf(' : ');

atomic_weight = [1 12 14 16 40];
MW = 0;
for i=1:length(species)
    for j=1:length(atomic_weight)
        if strcmp(species(i),atoms(j))
            MW = MW + atomic_weight(j);
            rank = j;
        end
    end
    
    %repeating weights
    n = str2num(species(i));
    if n>1
       MW=MW+atomic_weight(rank)*(n-1);
    end
end
end

molecular weight is calculated by using atomic weight of H,C,N,O, and A.
positions of these atom in a compound is used to determine the molecular weight.

3. Main Code:-

file = fopen('THERMO.dat','r');
file_header = fgetl(file);

temp = fgetl(file);
global_temp_range = strsplit(temp,' ');
glt = str2double(global_temp_range{2});
gmt = str2double(global_temp_range{3});
ght = str2double(global_temp_range{4});

R = 8.314;
T = linspace(glt,ght,500);

for i = 1:3
    skip=fgetl(file);
end

for j = 1:53
    line1 = fgetl(file);
    species = strtok(line1);
    
    line2 = fgetl(file);
    line3 = fgetl(file);
    line4 = fgetl(file);
    
    x = strfind(line2,'E');
    y = strfind(line3,'E');
    z = strfind(line4,'E');
    
    A1 = str2num(line2(1:x(1)+3));
    A2 = str2num(line2(x(1)+4:x(2)+3));
    A3 = str2num(line2(x(2)+4:x(3)+3));
    A4 = str2num(line2(x(3)+4:x(4)+3));
    A5 = str2num(line2(x(4)+4:x(5)+3));
    A6 = str2num(line3(1:y(1)+3));
    A7 = str2num(line3(y(1)+4:y(2)+3));
    
    a1 = str2num(line3(y(2)+4:y(3)+3));
    a2 = str2num(line3(y(3)+4:y(4)+3));
    a3 = str2num(line3(y(4)+4:y(5)+3));
    a4 = str2num(line4(1:z(1)+3));
    a5 = str2num(line4(z(1)+4:z(2)+3));
    a6 = str2num(line4(z(2)+4:z(3)+3));
    a7 = str2num(line4(z(3)+4:z(4)+3));
    
    % calculation of Specific Heat, Enthalpy, Entropy
    [Cp,H,S] = property(A1,A2,A3,A4,A5,A6,A7,a1,a2,a3,a4,a5,a6,a7,T,gmt);
    
    % calculation of Molecular Weight
    weight(i) = molecular_weight(species);
    
    %plotting
    figure(1)
    plot(T,Cp,'r','linewidth',2)
    xlabel('Temperature(K)')
    ylabel('Specific Heat(KJ)')
    title('Specific Heat vs Temperature')
    
    figure(2)
    plot(T,H,'g','linewidth',2)
    xlabel('Temperature(K)')
    ylabel('Enthalpy(KJ/mol)')
    title('Enthalpy vs Temperature')
    
    figure(3)
    plot(T,S,'b','linewidth',2)
    xlabel('Temperature(K)')
    ylabel('Entropy(KJ/mol*K)')
    title('Entropy vs Temperature')
    
    %saving
    cd('C:\Program Files\Polyspace\R2020a\Projects\Matlab\data_parsing')
    mkdir(species);
    cd(species);
    
    %saving plots
    saveas(figure(1), 'cp.png')
    saveas(figure(2), 'h.png')
    saveas(figure(3), 's.png')   
end

fopen is used to open the file
in syntax fopen('name','r') here r is used to read the file
temperature is divided in three parts, low, mid and high
str2num is used to convert character array or string to numeric array
by using strfind we can locate values with letter 'e' and thus coeeficients are calculated
for saving the file we have used syntax cd and mkdir where cd Change current folder and mkdir is responsible for making new folder
a for loop is used which incorporate the entire main program as there are 53 species

Results

Graph for O2