Project 1 - Parsing NASA thermodynamic data

Aim: To write a code in Matlab to parse the NASA thermodynamic data file and then calculate the thermodynamic properties of various gas species.

Objective :

1. To write a function that extracts the 14 coefficients and calculates the enthalpy, entropy, and specific heats for all the species in the NASA thermodynamic data file "Thermo.dat".

The NASA polynomials have the form as shown below:

Where R is the universal gas constant, T is the temperature

2. To calculate the molecular weight of each species and display it in the command window.
3. To plot the Cp, Enthalpy, and Entropy for the local temperature range (low temperature: high temperature) specific for each species.
4. To save the plots as images with appropriate names and dump them in separate folders for each species with suitable name automatically.

File Parsing:

File parsing refers to how information can be read from a particular text file or any type of file and how that information can be used in a computer program.

• Step 1 - Define the function
• Step 2 - Create an InputParser object
• Step 3 - Add inputs to the scheme.
• Step 4 - Set properties to adjust parsing.
• Step 5 - Parse the inputs.
• Step 6 - Use the inputs in function.
• Step 7 - Calling function.

NASA Thermodynamic File

THERMO.dat file is a data file containing 14 coefficients for 53 different elements given by NASA. These coefficients are utilized to calculate the specific heat, enthalpy & entropy for a particular element. Each element has its own range of local temperature. Below screenshot of the THERMO.dat file is displayed.

List of 53 Elements contained in 'THERMO.dat' file:

AR C C2H C2H2 C2H3 C2H4

C2H5 C2H6 C3H7 C3H8 CH CH2

CH2(S) CH2CHO CH2CO CH2O CH2OH CH3

CH3CHO CH3O CH3OH CH4 CN CO

CO2 H H2 H2CN H2O H2O2

HCCO CCOH HCN HCNN HCNO HCO

HNCO HNO HO2 HOCN N N2

N2O NCO NH NH2 NH3 NNH

NO NO2 O O2 OH

Enthalpy, Entropy, and Specific Heat:

Enthalpy, entropy, and specific heat, of various species values at different temperatures are required extensively to analyze the thermodynamic process.

For example, if the combustion process is considered during this, these quantities are required to observe how the combustion is going on and how efficient it will be. It eventually allows seeking the scope of improvement in the process. Similarly in the other processes like refrigeration, air conditioning, chemical kinetics, nozzle flow, detonation process, etc, these quantities are widely involved to observe the phenomenon.

NASA came up with polynomials that can be used to evaluate thermodynamic properties such as Cp, H, and S. They have documented the coefficients that are required to evaluate these polynomials for 1000+ species.

The NASA polynomials have the form:

Cp/R = a1 + a2 T + a3 T^2 + a4 T^3 + a5 T^4

H/RT = a1 + a2 T /2 + a3 T^2 /3 + a4 T^3 /4 + a5 T^4 /5 + a6/T

S/R = a1 lnT + a2 T + a3 T^2 /2 + a4 T^3 /3 + a5 T^4 /4 + a7

Where R is the universal gas constant, T is the temperature and a1, a2, a3, a4, a5, a6, and a7 are the numerical coefficients supplied in the thermodynamic file. The FIRST 7 coefficients are HIGH-temperature coefficients (above 1000 K) and the SECOND 7 coefficients are LOW-temperature coefficients (below 1000 K).

Coding Functions:

1. Specific Heat:

It is the amount of energy that must be added, in the form of heat, to one unit of mass of the substance in order to cause an increase of one unit in its temperature.

Cp = (a1 + a2 T + a3 T^2 + a4 T^3 + a5 T^4)*R

Function for Specific heat

% Specific heat calculation function

function Cp = Specificheat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,Temp,R,global_medium_temp)

% Comparing with global temperature

% If less than global temperature - minimum coefficients are taken

if Temp <= global_medium_temp

Cp = R*(a8 + (a9*Temp) + (a10*(Temp).^2) + (a11*(Temp).^3) + (a12*(Temp).^4));

else

Cp = R*(a1 + (a2*Temp) + (a3*(Temp).^2) + (a4*(Temp).^3) + (a5*(Temp).^4));

% Else maximum coefficients are taken

end

2. Entropy:

Entropy, the measure of a system’s thermal energy per unit temperature that is unavailable for doing useful work. Because work is obtained from ordered molecular motion, the amount of entropy is also a measure of the molecular disorder, or randomness, of a system. The concept of entropy provides deep insight into the direction of spontaneous change for many everyday phenomena.

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

% Entropy Calculation function

function S = Entropy_calc(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,Temp,R,global_medium_temp)

% Comparing with global temperature

% If less than global temperature - minimum coefficients are taken

if Temp <= global_medium_temp

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

else

% Else - maximum coefficients are taken

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

End

3. Enthalpy:

Enthalpy, a property of a thermodynamic system, is equal to the system's internal energy plus the product of its pressure and volume. In a system enclosed so as to prevent the mass transfer, for processes at constant pressure, the heat absorbed or released equals the change in enthalpy.

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

Function for Enthalpy:

% Enthalpy Calculation function

function H = Enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,Temp,R,global_medium_temp)

% Comparing with global temperature

% If less than global temperature - minimum coefficients are taken

if Temp <= global_medium_temp

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

else

% Else maximum coefficients are taken

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

end

4. Molecular Weight:

The molecular mass is the mass of a given molecule: it is measured in daltons. Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element.

Function for Molecular Weight:

% Molecular Weight Calculation function

function Molecularweight = Molecular_weight(Species_SP)

% Standard - Atomic Name

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

% Hydrogen, Carbon, Oxygen, Nitrogen, Argon

fprintf('Molecular Weight of ');

fprintf(Species_SP);

fprintf(' : ');

% Standard Atomic Number

Atomic_Weight = [1.008 12.011 15.999 14.007 39.948];

% Starting Range of Molecule

Molecularweight = 0;

% Adding Atomic number to obtain particular value

for i = 1:length(Species_SP)

for j = 1:length(atomic_name)

if strcmpi(Species_SP(i),atomic_name(j))

Molecularweight = Molecularweight +Atomic_Weight(j);

position = j;

end

end

n = str2num(Species_SP(i));

if n>1

Molecularweight = Molecularweight + Atomic_Weight(position)*(n-1);

end

end

fprintf('molecular weight %s :',Species_SP);

fprintf('%d',Molecularweight);

disp(' ');

end

Main Code:

clear all

close all

clc

% Make directory

mkdir 'C:\Users\Admin\Desktop\NASA File Parsing'

% Reading Data file - NASA Thermodynamic

% Open a file & 'r' Open the file for reading

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

gt=fgetl(f1);

% Obtaing Temperatures - by Reading Header Information

global_temp=fgetl(f1);

% Spliting

t=strsplit(global_temp);

% Converting string cells to numbers using str2num,

global_low_temp=str2num(t{2});

global_medium_temp=str2num(t{3});

global_high_temp=str2num(t{4});

% Temperature range & Gas Constant

% Temperature Range assumed

Temp=linspace(global_low_temp,global_high_temp,1000);

% Universal Gas Constant J/(mol-K)

R = 8.314;

% skipping three comment lines in the file

for i = 1:3

gt=fgetl(f1);

end

for i = 1:53

gt=fgetl(f1);

A=strsplit(gt,' ');

Species_SP=(A{1})

line_1=fgetl(f1) ;

a=strfind(line_1,'E');

% Extracting higher and lower temperature coefficients

% % Extracting FIRST 7 coefficients i.e HIGH-temperature coefficients

a1=line_1(1:a(1)+3);

a1=str2num(a1); %1

a2=line_1(a(1)+4:a(2)+3);

a2=str2num(a2) ; %2

a3=line_1(a(2)+4:a(3)+3);

a3=str2num(a3) ; %3

a4=line_1(a(3)+4:a(4)+3);

a4=str2num(a4); %4

a5=line_1(a(4)+4:a(5)+3);

a5=str2num(a5) ; %5

line_2=fgetl(f1);

b=strfind(line_1,'E');;

a6=line_2(1:b(1)+3);

a6=str2num(a6) ; %6

a7=line_2(a(1)+4:b(2)+3);

a7=str2num(a7); %7

% Extracting SECOND 7 coefficients - LOW-temperature coefficients

a8=line_2(b(2)+4:b(3)+3);

a8=str2num(a8); %8

a9=line_2(b(3)+4:b(4)+3);

a9=str2num(a9) ; %9

a10=line_2(b(4)+4:b(5)+3);

a10=str2num(a10) ; %10

line_3=fgetl(f1);

c=strfind(line_1,'E');

a11=line_3(1:c(1)+3);

a11=str2num(a11); %11

a12=line_3(c(1)+4:c(2)+3);

a12=str2num(a12); %12

a13=line_3(c(2)+4:c(3)+3);

a13=str2num(a13); %13

a14=line_3(c(3)+4:c(4)+3);

a14=str2num(a14); %14

% Specific heat calculation

Cp = Specificheat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,Temp,R,global_medium_temp);

% Enthalpy calculation

H = Enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,Temp,R,global_medium_temp);

% Entropy calculation

S = Entropy_calc(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,Temp,R,global_medium_temp);

% Calculating molecular weight of species

Molecularweight(i) = Molecular_weight(Species_SP);

% Read & Write Molecular list

Molecular_list = fopen('Molecular weight.txt','a+');

fprintf( Molecular_list,'Molecular weight of %s is %d \n',Species_SP,Molecularweight);

fclose(Molecular_list);

% plotting(CP,H,S,Temp,Species_SP)

% Saving as a folder

cur_dir=pwd;

mkdir(Species_SP);

cd(Species_SP);

% Plot 1, Specific heat (CP) vs Temperature Range (Temp)

figure(1)

plot(Temp,Cp,'linewidth',2,'color','r');

xlabel('Temperature [K]');

ylabel('Specific Heat [kJ]');

title(sprintf('Varying Specific Heat with Temperature Range of %s',Species_SP));

grid on

saveas(figure(1),'Specific Heat.jpg');

% Plot 2, Enthalpy (H) vs Temperature Range (Temp)

figure(2)

plot(Temp,H,'linewidth',2,'color','g');

xlabel('Temperature [K]');

ylabel('Enthalpy in [kJ/(mol)]');

title(sprintf('Varying Enthalpy with Temperature Range of %s',Species_SP));

grid on

saveas(figure(2),'Ethalpy.jpg');

% Plot 3, Entropy (S) vs Temperature Range (Temp)

figure(3)

plot(Temp,S,'linewidth',2,'color','b');

xlabel('Temperature [K]');

ylabel('Entropy in [kJ/(mol-K)]');

title(sprintf('Varying Entropy with Temperature Range of %s',Species_SP));

grid on

saveas(figure(3),'Entropy.jpg');

cd(cur_dir);

% Molecular weight

M = Molecular_weight(Species_SP)

f2 = fopen('molecular mass','w');

fprintf('%s n %s n %f n','species','Molecular mass',M)

fclose(f2)

end

Code Explanation:

1. 'clear all'- clear all the variables in the workspace,

'close all' - closes all the plots and figures and

'clc' - clears the command window.

2. Making a directory using 'mkdir' with location address.
3. After that, reading the text file 'Thermo.dat'file and opening it by using ‘fopen’ and 'r' as reading command.
4. For reading the line in a text file using ‘fgetl’.
5. To obtain the temperature range from the Thermo.dat file, using ‘strsplit’to split the temperature into a particular string cell.
6. Used ‘str2num’for converting string cell to numbers.
7. Divided the temperature into a string and then converted to a number so that temperature values can be used separately to solve the NASA thermodynamics.
8. Using ‘for & end’loops to skip the next three comment lines in the text file.
9. Reading all the 53 species to plot specific heat(cp), enthalpy(H), and entropy(S), with temperature values, and to find the molecular weights.
10. Used ‘for’loop to read 53 species.
11. Used ‘strfind’to find string.
12. Using 'linspace'specified the temperature range from low to high.
13. Adding universal gas constant value ‘R’.
14. Extracted higher and lower temperature coefficient by reading line by line from the species.
15. Calling specific heat, enthalpy, entropy function codes.
16. Calculating Molecular weight.

Attachment:

Screenshot of the window where all the folders are saved. :

Results:

Specific Heat, Entropy and Enthalpy Plots for O2, N2 and Co2 species :

• Plots for O2

Variation of Specific heat with the temperature of O2

Variation of Entropy with the temperature of O2

Variation of Enthalpy with the temperature of O2

• Plots for N2 :

Variation of Specific heat with the temperature of N2

Variation of Entropy with temperature of N2

Variation of Enthalpy with the temperature of N2

• Plots for Co2 :

Variation of Specific heat with the temperature of Co2

Variation of Entropy with the temperature of CO2

Variation of Enthalpy with the temperature of CO2

• Molecular Weight of all species :

References :

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

https://in.mathworks.com/matlabcentral/answers/317006-create-new-folders-by-mkdir

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

https://in.mathworks.com/matlabcentral/answers/17580-how-to-define-a-path-in-saveas-command

https://in.mathworks.com/help/matlab/referencelist.html?type=function&category=printing-and-exporting

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

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

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

http://combustion.berkeley.edu/gri-mech/data/nasa_plnm.html

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940013151.pdf