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

Function for Entropy:

% 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.

 

 

Syntax Used during Coding

Fopen :	Open a file or obtain information about open files
‘r’ :	Open the file for reading
fgetl	Read line from file
strsplit	Split string or character vector at specified delimiter
str2num	Convert character array or string to numeric array
strfind	Find one string within another
linspace	Generate linearly spaced vectors
fprintf	Write formatted data to file
pwd	Identify current directory
mkdir	Make new directory
cd	Change working directory

 

 

 

 

Output:

>> Molecular_weight AR

Molecular Weight of AR : molecular weight AR :3.994800e+01

 

ans =

 

   39.9480

 

>> Molecular_weight C

Molecular Weight of C : molecular weight C :1.201100e+01

 

ans =

 

   12.0110

 

>> Molecular_weight C2H

Molecular Weight of C2H : molecular weight C2H :2.503000e+01

 

ans =

 

   25.0300

 

>> Molecular_weight C2H2

Molecular Weight of C2H2 : molecular weight C2H2 :2.603800e+01

 

ans =

 

   26.0380

 

>> Molecular_weight C2H3

Molecular Weight of C2H3 : molecular weight C2H3 :2.704600e+01

 

ans =

 

   27.0460

 

>> Molecular_weight C2H4

Molecular Weight of C2H4 : molecular weight C2H4 :2.805400e+01

 

ans =

 

   28.0540

 

>> Molecular_weight C2H5

Molecular Weight of C2H5 : molecular weight C2H5 :2.906200e+01

 

ans =

 

   29.0620

 

>> Molecular_weight C2H6

Molecular Weight of C2H6 : molecular weight C2H6 :3.007000e+01

 

ans =

 

   30.0700

 

>> Molecular_weight C3H7

Molecular Weight of C3H7 : molecular weight C3H7 :4.308900e+01

 

ans =

 

   43.0890

 

>> Molecular_weight C3H8

Molecular Weight of C3H8 : molecular weight C3H8 :4.409700e+01

 

ans =

 

   44.0970

 

>> Molecular_weight CH

Molecular Weight of CH : molecular weight CH :1.301900e+01

 

ans =

 

   13.0190

 

>> Molecular_weight CH2

Molecular Weight of CH2 : molecular weight CH2 :1.402700e+01

 

ans =

 

   14.0270

 

>> Molecular_weight CH2(S)

Molecular Weight of CH2(S) : molecular weight CH2(S) :1.402700e+01

 

ans =

 

   14.0270

 

>> Molecular_weight CH2CHO

Molecular Weight of CH2CHO : molecular weight CH2CHO :4.304500e+01

 

ans =

 

   43.0450

 

>> Molecular_weight CH2CO

Molecular Weight of CH2CO : molecular weight CH2CO :4.203700e+01

 

ans =

 

   42.0370

 

>> Molecular_weight CH2O

Molecular Weight of CH2O : molecular weight CH2O :3.002600e+01

 

ans =

 

   30.0260

 

>> Molecular_weight CH2OH

Molecular Weight of CH2OH : molecular weight CH2OH :3.103400e+01

 

ans =

 

   31.0340

 

>> Molecular_weight CH3

Molecular Weight of CH3 : molecular weight CH3 :1.503500e+01

 

ans =

 

   15.0350

 

>> Molecular_weight CH3CHO

Molecular Weight of CH3CHO : molecular weight CH3CHO :4.405300e+01

 

ans =

 

   44.0530

 

>> Molecular_weight CH3O

Molecular Weight of CH3O : molecular weight CH3O :3.103400e+01

 

ans =

 

   31.0340

 

>> Molecular_weight CH3OH

Molecular Weight of CH3OH : molecular weight CH3OH :3.204200e+01

 

ans =

 

   32.0420

 

>> Molecular_weight CH4

Molecular Weight of CH4 : molecular weight CH4 :1.604300e+01

 

ans =

 

   16.0430

 

>> Molecular_weight CN

Molecular Weight of CN : molecular weight CN :2.601800e+01

 

ans =

 

   26.0180

 

>> Molecular_weight CO

Molecular Weight of CO : molecular weight CO :2.801000e+01

 

ans =

 

   28.0100

 

>> Molecular_weight CO2

Molecular Weight of CO2 : molecular weight CO2 :4.400900e+01

 

ans =

 

   44.0090

 

>> Molecular_weight H

Molecular Weight of H : molecular weight H :1.008000e+00

 

ans =

 

    1.0080

 

>> Molecular_weight H2

Molecular Weight of H2 : molecular weight H2 :2.016000e+00

 

ans =

 

    2.0160

 

>> Molecular_weight H2CN

Molecular Weight of H2CN : molecular weight H2CN :2.803400e+01

 

ans =

 

   28.0340

 

>> Molecular_weight H2O

Molecular Weight of H2O : molecular weight H2O :1.801500e+01

 

ans =

 

   18.0150

 

>> Molecular_weight H2O2

Molecular Weight of H2O2 : molecular weight H2O2 :3.401400e+01

 

ans =

 

   34.0140

 

>> Molecular_weight HCCO

Molecular Weight of HCCO : molecular weight HCCO :4.102900e+01

 

ans =

 

   41.0290

 

>> Molecular_weight HCCOH

Molecular Weight of HCCOH : molecular weight HCCOH :4.203700e+01

 

ans =

 

   42.0370

 

>> Molecular_weight HCN

Molecular Weight of HCN : molecular weight HCN :2.702600e+01

 

ans =

 

   27.0260

 

>> Molecular_weight HCNN

Molecular Weight of HCNN : molecular weight HCNN :4.103300e+01

 

ans =

 

   41.0330

 

>> Molecular_weight HCNO

Molecular Weight of HCNO : molecular weight HCNO :4.302500e+01

 

ans =

 

   43.0250

 

>> Molecular_weight HCO

Molecular Weight of HCO : molecular weight HCO :2.901800e+01

 

ans =

 

   29.0180

 

>> Molecular_weight HNCO

Molecular Weight of HNCO : molecular weight HNCO :4.302500e+01

 

ans =

 

   43.0250

 

>> Molecular_weight HNO

Molecular Weight of HNO : molecular weight HNO :3.101400e+01

 

ans =

 

   31.0140

 

>> Molecular_weight HO2

Molecular Weight of HO2 : molecular weight HO2 :3.300600e+01

 

ans =

 

   33.0060

 

>> Molecular_weight HOCN

Molecular Weight of HOCN : molecular weight HOCN :4.302500e+01

 

ans =

 

   43.0250

 

>> Molecular_weight N

Molecular Weight of N : molecular weight N :1.400700e+01

 

ans =

 

   14.0070

 

>> Molecular_weight N2

Molecular Weight of N2 : molecular weight N2 :2.801400e+01

 

ans =

 

   28.0140

 

>> Molecular_weight N2O

Molecular Weight of N2O : molecular weight N2O :4.401300e+01

 

ans =

 

   44.0130

 

>> Molecular_weight NCO

Molecular Weight of NCO : molecular weight NCO :4.201700e+01

 

ans =

 

   42.0170

 

>> Molecular_weight NH

Molecular Weight of NH : molecular weight NH :1.501500e+01

 

ans =

 

   15.0150

 

>> Molecular_weight NH2

Molecular Weight of NH2 : molecular weight NH2 :1.602300e+01

 

ans =

 

   16.0230

 

>> Molecular_weight NH3

Molecular Weight of NH3 : molecular weight NH3 :1.703100e+01

 

ans =

 

   17.0310

 

>> Molecular_weight NNH

Molecular Weight of NNH : molecular weight NNH :2.902200e+01

 

ans =

 

   29.0220

 

>> Molecular_weight NO

Molecular Weight of NO : molecular weight NO :3.000600e+01

 

ans =

 

   30.0060

 

>> Molecular_weight NO2

Molecular Weight of NO2 : molecular weight NO2 :4.600500e+01

 

ans =

 

   46.0050

 

>> Molecular_weight O

Molecular Weight of O : molecular weight O :1.599900e+01

 

ans =

 

   15.9990

 

>> Molecular_weight O2

Molecular Weight of O2 : molecular weight O2 :3.199800e+01

 

ans =

 

   31.9980

 

>> Molecular_weight OH

Molecular Weight of OH : molecular weight OH :1.700700e+01

 

ans =

 

   17.0070

 

 

 

 

Attachment:   

 

        

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

 

 

Results:

 

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

 

1. Plots for O2

 

a. Variation of Specific heat with the temperature of O2 

 

 

b. Variation of Entropy with the temperature of O2

 

 

c. Variation of Enthalpy with the temperature of O2

 

 

 

 

2. Plots for N2 :

 

 

a. Variation of Specific heat with the temperature of N2 

 

 

b. Variation of Entropy with temperature of N2

 

 

c. Variation of Enthalpy with the temperature of N2

 

 

 

3. Plots for Co2 :

 

 

a. Variation of Specific heat with the temperature of Co2 

 

 

b. Variation of Entropy with the temperature of CO2

 

 

c. Variation of Enthalpy with the temperature of CO2

 

 

 

 

Molecular Weight of all species : 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Conclusion :

Using MATLAB code, the necessary coefficients required to evaluate various thermodynamic parameters for different species are extracted from NASA thermodynamic data file. The specific heat, enthalpy, and entropy for all the species are calculated and plotted against the local temperature range. The molecular weight is calculated for all the species.