Project 1 - Parsing NASA thermodynamic data

Report on Parsing NASA thermodynamic data

Aim:

• 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.

Software Used: MATLAB.

Code:

% Parsing Of NASA Thermodynamic Data

clear all

close all

clc

% Open the thermodynamic data file

f1 = fopen('THERMO.dat', 'r');

fgetl(f1); % Skip header line

% Read global temperature limits

global_header_temperature = fgetl(f1);

A = strsplit(global_header_temperature); % Corrected string split

global_low_temperature = str2double(A{2});

global_mid_temperature = str2double(A{3});

global_high_temperature = str2double(A{4});

% Skip theoretical data header

for i = 1:3

fgetl(f1);

end

for i = 1:53 % Iterate over species

% Read species data

tline1 = fgetl(f1);

tline2 = fgetl(f1);

tline3 = fgetl(f1);

tline4 = fgetl(f1);

% Extract species name and temperature limits

loc_temp = strsplit(tline1, ' ');

species_name = strtrim(loc_temp{1}); % Ensure no spaces

loc_low_temp = str2double(loc_temp{end-3});

loc_mid_temp = str2double(loc_temp{end-2});

loc_high_temp = str2double(loc_temp{end-1});

% Extract coefficients

a = findstr(tline2, 'E');

a1 = str2double(tline2(1:a(1)+3));

a2 = str2double(tline2(a(1)+4:a(2)+3));

a3 = str2double(tline2(a(2)+4:a(3)+3));

a4 = str2double(tline2(a(3)+4:a(4)+3));

a5 = str2double(tline2(a(4)+4:a(5)+3));

a = findstr(tline3, 'E');

a6 = str2double(tline3(1:a(1)+3));

a7 = str2double(tline3(a(1)+4:a(2)+3));

a8 = str2double(tline3(a(2)+4:a(3)+3));

a9 = str2double(tline3(a(3)+4:a(4)+3));

a10 = str2double(tline3(a(4)+4:a(5)+3));

a = findstr(tline4, 'E');

a11 = str2double(tline4(1:a(1)+3));

a12 = str2double(tline4(a(1)+4:a(2)+3));

a13 = str2double(tline4(a(2)+4:a(3)+3));

a14 = str2double(tline4(a(3)+4:a(4)+3));

% Compute thermodynamic properties

R = 8.314;

T = linspace(loc_low_temp, loc_high_temp, 300);

cp = specific_heat(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, R, T, loc_mid_temp);

H = enthalpy(a1, a2, a3, a4, a5, a6, a8, a9, a10, a11, a12, a13, loc_mid_temp, T);

S = entropy(a1, a2, a3, a4, a5, a7, a8, a9, a10, a11, a12, a14, loc_mid_temp, T);

% Create directory and save plots

base_folder = pwd;

mkdir(fullfile(base_folder, species_name));

cd(fullfile(base_folder, species_name));

figure(1);

plot(cp, T, 'r', 'LineWidth', 3);

title(['Specific Heat vs Temperature - ' species_name]);

xlabel('Specific Heat [J/K]');

ylabel('Temperature [K]');

grid on;

saveas(gcf, 'cp_vs_T.jpeg');

figure(2);

plot(H, T, 'b', 'LineWidth', 3);

title(['Enthalpy vs Temperature - ' species_name]);

xlabel('Enthalpy [J]');

ylabel('Temperature [K]');

grid on;

saveas(gcf, 'H_vs_T.jpeg');

figure(3);

plot(S, T, 'g', 'LineWidth', 3);

title(['Entropy vs Temperature - ' species_name]);

xlabel('Entropy [kJ/mol]');

ylabel('Temperature [K]');

grid on;

saveas(gcf, 'S_vs_T.jpeg');

% Compute molecular weight

molecular_weight = mol_weight(species_name);

end

Enthalpy

%Function program for enthalpy

function[H] = enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,loc_mid_temp,T)

R = 8.314;

if (T>loc_mid_temp)

H = ((a1+((a2*T)/2)+(a3*(T.^2))/3)+((a4*(T.^3))/4)+((a5*(T.^4))/5)+(a6./T)).*T*R;

else

H = ((a8+((a9*T)/2)+((a10*T.^2))/3)+((a11*(T.^3))/4)+((a12*(T.^4))/5)+(a13./T)).*T*R;

end

Entropy

%function code to find the entropy

function[S] = entropy(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,loc_mid_temp,T)

R = 8.314;

if (T>loc_mid_temp)

S = R*(a1*logT)+(a2*T)+((a3*(T.^2))/2)+((a4*(T.^3)/3)+(a5*(T.^4)/4)+a7);

else

S = R*((a8*log(T)+(a9*T)+(a10*(T.^2)/2)+(a11*(T.^3))/3)+(a12*(T.^4)/4)+a14);

end

Molecular weight

function [w]=mol_weight(species_name)

atomic_names=['H', 'C', 'O', 'N', 'A'];

atomic_weights=[1.00784,12.0107,15.999,14.0067,39.948];

w=0;

for i=1:length(species_name)

for j=1:length(atomic_names)

if strcmpi(species_name(i), atomic_names (j))

w=w+atomic_weights(j);

pos=j;

end

end

n=str2double(species_name(i));

if n>1

w =w+atomic_weights(pos)*(n-1);

end

end

fprintf('Molecular weight of %s = %f', species_name, w);

end

Explanation:

• Opens the NASA thermodynamic data file (THERMO.dat).
• fgetl(f1) skips the header line.
• Reads global temperature limits from the second line.
• Converts temperature strings into numerical values.
• Reads four lines per species.
• Stores species name and temperature limits.
• Extracts species Name (first entry in tline1) and Low, Mid, and High Temperatures (last three entries).
• findstr(tline2, 'E') finds scientific notation coefficients (e.g., 2.543E+01).
• Extracts and converts coefficients for Cp, H, and S.
• Similar extraction is repeated for tline3 and tline4 to get all 14 coefficients.
• Uses NASA polynomial equations to compute Specific Heat Capacity (Cp),Enthalpy (H),Entropy (S).
• Calls three functions (specific_heat, enthalpy, entropy).
• Plots Cp vs. T in red and saves the figure as 'cp vs T.jpeg'.
• Plots H vs. T in blue.
• Plots S vs. T in green.
• Creates a folder for the species.
• Saves plots in the folder.
• Calls mol_weight(species_name), which extracts elements from the species name and computes total molecular weight.
• Uses NASA polynomials to compute enthalpy, entropy, Molecular weight.

Result:

Conclusion:

• The 14 co-efficients are extracted and the enthalpy, entropy and specific heats for all the species in the data file are calculated.