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Project 1 - Parsing NASA thermodynamic data

HHari Venkatesh Y25 Jun 2021
MATLAB

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 https://drive.google.com/file/d/1AikCHDlz9s_fu8whE81qee_GD4AyYpCP/view?usp=sharing.

OBJECTIVES:

  • Create a function that extracts the 14 co-efficients and calculates the enthalpy, entropy and specific heats.

  • Calculate the molecular weight of each species and display it in the command window.

  • Plot the Cp, Enthalpy and Entropy for the local temperature range (low temperature : high temperature) specific for each species.

  • Save the plots as images with appropriate names and dump them in separate folders for each species with suitable name.

  • The main program will just take the "THERMO.dat" file as an input and generate Cp, H and S plots.

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

  • Plots for o2, N2 and Co2 species.

EQUATIONS:

where, Cp - Specific heat (KJ/kgk)

R - Gas constant (J/mol*k)

T - Temperature (k)

S - Entropy (J/k)

PROCEDURE:

  • Starting a program in MATLAB with the following commands :
  1. clear all - To clear all datas stored in workspace.
  2. close all - To close previous figures and plots.
  3. clc - To clear the command window.
  • Load the data using 'load' command.
  • 'fgetl' returns an output that displays in one line
  • String split command 'strsplit' creates the space between the variables in the loaded file.
  • 'str2num' converts a character array or string scalar to a numeric matrix.
  • Enter the input varible global temperature.
  • Use for-loop command to get 14 coefficients value to be entered in deriavtives of Cp,H,S.
  • Coefficients can be derived by solving the respective deriavtives by using the string values of the data file.
  • The derivatives of Cp,H,S should be converted as fucntion variables and save it in separate file.
  • Using if-else command to define whether the given local temperature is greater than mid temperature, else use the high temp[perature values.
  • Then the call function in the program and save it in separate folder and directory as well.
  • Now enter the varibles to calculate molecular weight.
  • The variables can be entered in for-loop command and if-else command .
  • The varibles of if-else can be converted in double precison values from strings.
  • Using 'plot' command, we can derive the Cp,H,S graph for all states of variables.
  • Also use color and linewidth commands to use respective fucntion.
  • By using 'axis' command and enter the required axis value.
  • Then name the x-axis using 'xlabel' command and y-axis using 'ylabel' command.
  • Enter the title of the graph using 'title' command.
  • Use getframe command to capture the current axes and save it in separate file, directory.
  • Display the molecular weight in fprintf command.

CODE:

function [Cp,H,S]=nasa(A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,A11,A12,A13,A14,local_low_temp,local_mid_temp,local_high_temp,local_temp)
R=8.314;          % gas constant
% low temperature range
Lt=linspace(local_low_temp,local_mid_temp,300);

% High temperatuer range
Ht=linspace(local_mid_temp,local_high_temp,300);

if (local_temp>=local_mid_temp)
    Cp=(A1+A2.*Ht+A3.*(Ht).^2+A4.*(Ht).^3+A5.*(Ht).^4).*R;
    H=(A1+((A2.*Ht)./2)+((A3.*Ht).^2)./3+((A4.*Ht).^3)./4+((A5.*Ht).^4)./5+A6.*Ht).*R.*Ht;
    S=(A1.*log(Ht)+A2.*Ht+((A3.*(Ht).^2)./2)+((A4.*(Ht).^3)./3)+((A5.*(Ht).^4)./4)+A7).*R;
else
     Cp=(A1+A2.*Lt+A3.*(Lt).^2+A4.*(Lt).^3+A5.*(Lt).^4).*R;
    H=(A1+((A2.*Lt)./2)+((A3.*Lt).^2)./3+((A4.*Lt).^3)./4+((A5.*Lt).^4)./5+A6.*Lt).*R.*Lt;
    S=(A1.*log(Lt)+A2.*Lt+((A3.*(Lt).^2)./2)+((A4.*(Lt).^3)./3)+((A5.*(Lt).^4)./4)+A7).*R;
end
end
% A program on parsing NASA thermodynamic data.
clear all
close all
clc

% To load the data
file=fopen('THERMO.dat','r');

% Define the temperature
Title=fgetl(file);
string_temp=fgetl(file);
strsplit(string_temp,' ');
a=str2num(string_temp);
global_low_temp=a(1);
global_mid_temp=a(2);
global_high_temp=a(3);

% Ignore the comments
for i=1:3
    ignore=fgetl(file);
end

for j=1:53
    % Define local temperature
    string_local1=fgetl(file);
    a1=strsplit(string_local1);
    species_name=a1{1};
    
    local_low_temp=str2double(a1(end-3));
    local_mid_temp=str2double(a1(end-1));
    local_high_temp=str2double(a1(end-2));
    local_temp=linspace(local_low_temp,local_high_temp,300);
    
    % Extracting coefficient string
    a4=fgetl(file);
    a5=findstr(a4,'E');
    
    A1=a4(a5(1)-10:a5(1)+3);
    A2=a4(a5(2)-10:a5(2)+3);
    A3=a4(a5(3)-10:a5(3)+3);
    A4=a4(a5(4)-10:a5(4)+3);
    A5=a4(a5(5)-10:a5(5)+3);
    
    a4=fgetl(file);
    a5=findstr(a4,'E');
    
    A6=a4(a5(1)-10:a5(1)+3);
    A7=a4(a5(2)-10:a5(2)+3);
    A8=a4(a5(3)-10:a5(3)+3);
    A9=a4(a5(4)-10:a5(4)+3);
    A10=a4(a5(5)-10:a5(5)+3);
    
    a4=fgetl(file);
    a5=findstr(a4,'E');
    
    A11=a4(a5(1)-10:a5(1)+3);
    A12=a4(a5(2)-10:a5(2)+3);
    A13=a4(a5(3)-10:a5(3)+3);
    A14=a4(a5(4)-10:a5(4)+3);
    
    % convert strings to nuumbers
   A1=str2num(A1);
   A2=str2num(A2);
   A3=str2num(A3);
   A4=str2num(A4);
   A5=str2num(A5);
   A6=str2num(A6);
   A7=str2num(A7);
   A8=str2num(A8);
   A9=str2num(A9);
   A10=str2num(A10);
   A11=str2num(A11);
   A12=str2num(A12);
   A13=str2num(A13);
   A14=str2num(A14);
   
   % Call the function of Cp,H,S
   [Cp,H,S]=nasa(A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,A11,A12,A13,A14,local_low_temp,local_mid_temp,local_high_temp,local_temp);
   
   % create individual folder and save it
   data=sprintf('%s',species_name);
   c_d=pwd;
   
   % make directory and create folders
   mkdir(data);
   cd(data);
   
   % calculate molecular weight
   element={'H','C','N','O','A'};
   atomic_weight=[1,12,14,16,40];
   mol_weight=0;
   
   for k=1:length(species_name)
       for m=1:length(element)
           if strcmp(species_name(k),element(m))==1
               mol_weight=mol_weight+atomic_weight(m);
               d=m;
           end
       end
       p=str2double(species_name(k));
       if p>1
           mol_weight=mol_weight+((atomic_weight(d))*(p-1));
       end
   end
   
   % plotting
   % plot Specific heat
   figure(1)
   plot(local_temp,Cp,'linewidth',2,'color','r');
   xlabel('local temperature range');
   ylabel('specific heat');
   title('specific heat vs temperature');
   
   % saving the specific heat file in png
   getframe(gcf);
   saveas(1,'graph of specific heat.png');
   
   % plot enthalpy
   figure(2)
   plot(local_temp,H,'linewidth',2,'color','b');
   xlabel('local temperature range');
   ylabel('enthalpy');
   title('Enthalpy vs temperature');
   
   % saving the Enthalpy file in png
   getframe(gcf);
   saveas(2,'graph of Enthalpy.png');
  
   % plot entropy
   figure(3)
   plot(local_temp,S,'linewidth',2,'color','g');
   xlabel('local temperature range');
   ylabel('entropy');
   title('entropy vs temperature');
   
   % saving the entropy file in png
   getframe(gcf);
   saveas(3,'graph of entropy.png');
   
   % setting current directory as c_d
   cd(c_d);
   
   % displaying the molecular weight
   fprintf('Molecular weight of [%s] - %du n',species_name,mol_weight)
end

OUTPUT:

MOLECULAR WEIGHT:

  • Molecular weight of [O] - 16u
  • Molecular weight of [O2] - 32u
  • Molecular weight of [H] - 1u
  • Molecular weight of [H2] - 2u
  • Molecular weight of [OH] - 17u
  • Molecular weight of [H2O] - 18u
  • Molecular weight of [HO2] - 33u
  • Molecular weight of [H2O2] - 34u
  • Molecular weight of [C] - 12u
  • Molecular weight of [CH] - 13u
  • Molecular weight of [CH2] - 14u
  • Molecular weight of [CH2(S)] - 14u
  • Molecular weight of [CH3] - 15u
  • Molecular weight of [CH4] - 16u
  • Molecular weight of [CO] - 28u
  • Molecular weight of [CO2] - 44u
  • Molecular weight of [HCO] - 29u
  • Molecular weight of [CH2O] - 30u
  • Molecular weight of [CH2OH] - 31u
  • Molecular weight of [CH3O] - 31u
  • Molecular weight of [CH3OH] - 32u
  • Molecular weight of [C2H] - 25u
  • Molecular weight of [C2H2] - 26u
  • Molecular weight of [C2H3] - 27u
  • Molecular weight of [C2H4] - 28u
  • Molecular weight of [C2H5] - 29u
  • Molecular weight of [C2H6] - 30u
  • Molecular weight of [CH2CO] - 42u
  • Molecular weight of [HCCO] - 41u
  • Molecular weight of [HCCOH] - 42u
  • Molecular weight of [H2CN] - 28u
  • Molecular weight of [HCN] - 27u
  • Molecular weight of [HNO] - 31u
  • Molecular weight of [N] - 14u
  • Molecular weight of [NNH] - 29u
  • Molecular weight of [N2O] - 44u
  • Molecular weight of [NH] - 15u
  • Molecular weight of [NH2] - 16u
  • Molecular weight of [NH3] - 17u
  • Molecular weight of [NO] - 30u
  • Molecular weight of [NO2] - 46u
  • nMolecular weight of [HCNO] - 43u
  • Molecular weight of [HOCN] - 43u
  • Molecular weight of [HNCO] - 43u
  • Molecular weight of [NCO] - 42u
  • Molecular weight of [CN] - 26u
  • Molecular weight of [HCNN] - 41u
  • Molecular weight of [N2] - 28u
  • Molecular weight of [AR] - 40u
  • Molecular weight of [C3H8] - 44u
  • Molecular weight of [C3H7] - 43u
  • Molecular weight of [CH3CHO] - 44u
  • Molecular weight of [CH2CHO] - 43u

SCREENSHOT OF ALL SPECIES DATA FILE:

Cp,H,S PLOT OF O2

Cp,H,S PLOT OF CO2

Cp,H,S PLOT OF N2

ERRORS:

  • In 'fgetl' command, I made an error by placing 1 instead of L (lowercase).

  • Without using the split string command, the datas cannot be separated by space.

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