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Project 1 - Parsing NASA thermodynamic data

RRushikesh Khondekar14 Sept 2021
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Aim:

The main is as follows:

  1. To write the function that extracts the 14 coefficients and calculates the enthalpy, entropy, and specific heats for all the species in the data file.
  2. To calculate the molecular weight of each species and display it in the command window.
  3. Plot the Cp, Enthalpy, and Entropy for the local temperature range (low temperature: high temperature) specific for each species.
  4. Save the plots as images with appropriate names and dump them in separate folders for each species with a suitable name. All these should be generated automatically.

Introduction:

Data parsing is a method where one string of data gets converted into a different type of data. So let's say you receive your data in raw HTML, a parser will take the said HTML and transform it into a more readable data format that can be easily read and understood.

Equation used:

Procedure:

Functions:

For Molecular weight: To calculate the molecular weight for each element.

function [Mole] = molecular_wt(species)

%Define Atom and its Atomic weight
element = ['H' 'C' 'N' 'O' 'Ar'];
Atomic_weight = [1.008,12.011,14.007,15.999,39.948];
Mole=0;

for i = 1:length(species)
    for j=1:length(element)
        if strcmp(species(i),element(j))
            Mole=Mole+Atomic_weight(j);
            x = j;
        end
    end
    l = str2num(species(i));
    if(l>1)
        Mole = Mole+Atomic_weight(x)*(l-1);
    end
end
fprintf('Molecular weight of %s: ', species);
fprintf('%f',Mole);
disp(' ');
end

For Specific heat: To calculate the Specific heat for temperature range for each element.

function CP=CP_High(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,low_temp,mid_temp,high_temp,R,species)
  %temperture is taken into range of low to high 
  T=low_temp:high_temp;
  %if else for temperature below and above midtemp of given species and formula for each of them.
  if T>mid_temp
    CP=(a1+(a2*T)+(a3*(T.^2))+(a4*(T.^3))+(a5*(T.^4)))*R;
  else
    CP=(a8+(a9*T)+(a10*(T.^2))+(a11*(T.^3))+(a12*(T.^4)))*R;
  end
 
end

For Entropy: To calculate the Entropy for temperature range for each element.

function S=S_High(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,low_temp,mid_temp,high_temp,R,species)
  %temperture is taken into range of low to high 
  T=low_temp:high_temp;
  %if else for temperature below and above midtemp of given species and formula for each of them.
  if T>mid_temp
    S=((a1*log(T))+(a2*T)+(a3*(T.^2)/2)+(a4*(T.^3)/3)+(a5*(T.^4)/4)+a7)*R;
  else
    S=((a8*log(T))+(a9*T)+(a10*(T.^2)/2)+(a11*(T.^3)/3)+(a12*(T.^4)/4)+a14)*R;
  end
  
end

For Enthalpy: To calculate the Enthalpy for temperature range for each element.

function H=H_High(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,low_temp,mid_temp,high_temp,R,species)
  %temperture is taken into range of low to high 
  T=low_temp:high_temp;
  %if else for temperature below and above midtemp of given species and formula for each of them.
  if T>mid_temp
      H=(a1+(a2*T/2)+(a3*(T.^2)/3)+(a4*(T.^3)/4)+(a5*(T.^4)/5)+a6*(T)).*R.*T;
  else
      H=(a8+(a9*T/2)+(a10*(T.^2)/3)+(a11*(T.^3)/4)+(a12*(T.^4)/5)+a13*(T)).*R.*T;
  end
  
end

Main code:

  • Initially, the code starts with clear all, close all, and clc.
  • Next, store the file where the program is going to save and open the file by using the ‘fopen’ function.
clear all
close all
clc

%Reading NASA's thermodynamics data by using fopen(fileopen) command.

data_file = fopen('THERMO.dat','r');
  • To read the data in the file, the ‘fgetl’ function is used.
  • The first five(5) lines are considered as comments.
%For skipping unwanted lines.

for i=1:5
line=fgetl(data_file);
end
  • The second line consists of a Global temperature line from low to the high-temperature range.
  • The temperature range is calculated by using the ‘strsplit’ function.
    string_1 = fgetl(data_file);
    l = strsplit(string_1,' ');
    m = length(l);
    species_cell= l(1);
    species=char(species_cell);
  • Local Low temperature is calculated with the low and mid-temperature ranges.
  • Local High temperature is calculated with the mid and high-temperature ranges.
    %Defining local temp values
 
    low_temp = str2double(l(m-3));
    mid_temp = str2double(l(m-2));
    high_temp = str2double(l(m-1));
    %Reading temperature values for lower and higher temp
    lower_temp = linspace(low_temp,mid_temp,100);
    higher_temp = linspace(mid_temp,high_temp,100);
    T=low_temp:high_temp;
  • For the 14 coefficients, write in the for loop to extract it.
  %Storing the value for the 2nd line of variable
    string_2 = fgetl(data_file);
    
    %Finding the position of E
    a = strfind(string_2,'E');
    
    %Reading all the variables
    a1 = str2double(string_2(1:(a(1)+3)));
    a2 = str2double(string_2((a(1)+4):(a(2)+3)));
    a3 = str2double(string_2((a(2)+4):(a(3)+3)));
    a4 = str2double(string_2((a(3)+4):(a(4)+3)));
    a5 = str2double(string_2((a(4)+4):(a(5)+3)));
    
    %Storing the values of the 3rd line
    string_3 = fgetl(data_file);
    
    %Finding the position of E
    b = strfind(string_3,'E');
    
    %Reading the varibles 
    a6 = str2double(string_3(1:(b(1)+3)));
    a7 = str2double(string_3(1:(b(1)+4):(b(2)+3)));
    a8 = str2double(string_3(1:(b(2)+4):(b(3)+3)));
    a9 = str2double(string_3(1:(b(3)+4):(b(4)+3)));
    a10 = str2double(string_3(1:(b(4)+4):(b(5)+3)));
    
    %Storing the values of the 4th line
    string_4 = fgetl(data_file);
    
    %Finding the variables
    c = strfind(string_4,'E');
    
    %Reading the variables
    a11 = str2double(string_4(1:(c(1)+3)));
    a12 = str2double(string_3(1:(c(1)+4):(c(2)+3)));
    a13 = str2double(string_3(1:(c(2)+4):(c(3)+3)));
    a14 = str2double(string_3(1:(c(3)+4):(c(4)+3)));
  • Calling the molecular function to calculate the molecular weight of every species.
    %Calculating molecular weight of each species
    Molecular_weight = molecular_wt(species);
    sprintf('Molecular weight of %s = %d',species, Molecular_weight)
  • Similarly, the function is called for the calculation of specific heat(Cp), Enthalpy(H), and Entropy(C) for Low and High Temperatures and stored the value in each separate array.
    %Calculating the value for Cp, H and S using formula
    %Calling the function
    CP= CP_High(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,low_temp,mid_temp,high_temp,R,species);
    S= S_High(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,low_temp,mid_temp,high_temp,R,species);
    H=H_High(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,low_temp,mid_temp,high_temp,R,species);
  • Create the new folder of the name of species and save the values of Cp, H, and S vs Temperature respectively.
    %Creates a new folder of name of species and saves CP, H, S vs T plots separately
    t=sprintf('%s', species);
    mkdir(t)
    cd(t)
  • Plotting the graph for Specific Heat(Cp) vs Temperature, Entropy(S) vs Temperature and Enthalpy(H) vs Temperature,
    %PLot for Specific Heat(Cp) vs Temperature
    figure(1)
    plot(CP,T,'linewidth',2,'color','r')
    title(sprintf('Specific Heat vs Temperature For %s',species))
    xlabel('Temperature(K)')
    ylabel('Specific Heat(J/K-kg)')
    file=sprintf('CP.png');
    saveas (1, file);
    
    %PLot for Entropy(S) vs Temperature
    figure(2)
    plot(S,T,'linewidth',2,'color','g')
    title(sprintf('Entropy vs Temperature For %s',species))
    xlabel('Temperature(K)')
    ylabel('Entropy(J/K)')
    file=sprintf('S.png');
    saveas (2, file);
    
    %PLot for Enthalpy(H) vs Temperature
    figure(3)
    plot(H,T,'linewidth',2,'color','b')
    title(sprintf('Enthalpy vs Temperature For %s',species))
    xlabel('Temperature(K)')
    ylabel('Enthalpy(J/kg)')
    file=sprintf('H.png');
    saveas (3, file);
    cd ..

Complete code:

Main code:

clear all
close all
clc

%Reading NASA's thermodynamics data by using fopen(fileopen) command.

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

%For skipping unwanted lines.

for i=1:5
line=fgetl(data_file);
end

%To check if we are in the species line

for i = 1:53
    
    string_1 = fgetl(data_file);
    l = strsplit(string_1,' ');
    m = length(l);
    species_cell= l(1);
    species=char(species_cell);
    
    % To find the temperature ranges, the Data file is checked.
    % First Temperature is low Temperature
    % Middle one being the High Temperature and Last one is the mid Temperature.
    
    %Defining local temp values
 
    low_temp = str2double(l(m-3));
    mid_temp = str2double(l(m-2));
    high_temp = str2double(l(m-1));
    
    %Storing the value for the 2nd line of variable
    string_2 = fgetl(data_file);
    
    %Finding the position of E
    a = strfind(string_2,'E');
    
    %Reading all the variables
    a1 = str2double(string_2(1:(a(1)+3)));
    a2 = str2double(string_2((a(1)+4):(a(2)+3)));
    a3 = str2double(string_2((a(2)+4):(a(3)+3)));
    a4 = str2double(string_2((a(3)+4):(a(4)+3)));
    a5 = str2double(string_2((a(4)+4):(a(5)+3)));
    
    %Storing the values of the 3rd line
    string_3 = fgetl(data_file);
    
    %Finding the position of E
    b = strfind(string_3,'E');
    
    %Reading the varibles 
    a6 = str2double(string_3(1:(b(1)+3)));
    a7 = str2double(string_3(1:(b(1)+4):(b(2)+3)));
    a8 = str2double(string_3(1:(b(2)+4):(b(3)+3)));
    a9 = str2double(string_3(1:(b(3)+4):(b(4)+3)));
    a10 = str2double(string_3(1:(b(4)+4):(b(5)+3)));
    
    %Storing the values of the 4th line
    string_4 = fgetl(data_file);
    
    %Finding the variables
    c = strfind(string_4,'E');
    
    %Reading the variables
    a11 = str2double(string_4(1:(c(1)+3)));
    a12 = str2double(string_3(1:(c(1)+4):(c(2)+3)));
    a13 = str2double(string_3(1:(c(2)+4):(c(3)+3)));
    a14 = str2double(string_3(1:(c(3)+4):(c(4)+3)));
    
    %Calculating molecular weight of each species
    Molecular_weight = molecular_wt(species);
    sprintf('Molecular weight of %s = %d',species, Molecular_weight)
    
    %Reading temperature values for lower and higher temp
    lower_temp = linspace(low_temp,mid_temp,100);
    higher_temp = linspace(mid_temp,high_temp,100);
    T=low_temp:high_temp;

    %Values of the universal gas constant in J/mol-K
    R = 8.314;
    
    %Calculating the value for Cp, H and S using formula
    %Calling the function
    CP= CP_High(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,low_temp,mid_temp,high_temp,R,species);
    S= S_High(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,low_temp,mid_temp,high_temp,R,species);
    H=H_High(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,low_temp,mid_temp,high_temp,R,species);
    
    %Creates a new folder of name of species and saves CP, H, S vs T plots separately
    t=sprintf('%s', species);
    mkdir(t)
    cd(t)
    
    %PLot for Specific Heat(Cp) vs Temperature
    figure(1)
    plot(CP,T,'linewidth',2,'color','r')
    title(sprintf('Specific Heat vs Temperature For %s',species))
    xlabel('Temperature(K)')
    ylabel('Specific Heat(J/K-kg)')
    file=sprintf('CP.png');
    saveas (1, file);
    
    %PLot for Entropy(S) vs Temperature
    figure(2)
    plot(S,T,'linewidth',2,'color','g')
    title(sprintf('Entropy vs Temperature For %s',species))
    xlabel('Temperature(K)')
    ylabel('Entropy(J/K)')
    file=sprintf('S.png');
    saveas (2, file);
    
    %PLot for Enthalpy(H) vs Temperature
    figure(3)
    plot(H,T,'linewidth',2,'color','b')
    title(sprintf('Enthalpy vs Temperature For %s',species))
    xlabel('Temperature(K)')
    ylabel('Enthalpy(J/kg)')
    file=sprintf('H.png');
    saveas (3, file);
    cd ..
 end

Output:

Directory of each and every species with its respective name

The molecular weight of species with its respective name

Plot for the O2:

Specific Heat vs Temperature:

Enthalpy vs Temperature:

Entropy vs Temperature:

Plot for CO2:

Specific Heat vs Temperature:

Enthalpy vs Temperature:

Entropy vs Temperature:

Plot for N2:

Specific Heat vs Temperature:

Enthalpy vs Temperature:

Entropy vs Temperature:

Results:

  • Molecular weight is calculated of a species from the NASA Thermo file.
  • The successfully extracted species name, temperatures, coefficients for each of the elements.

Conclusion:

  • Understanding the basic concept behind file parsing helps in creating variables to run a calculation for plotting Cp, H, S graphs. for different species.
  • Achieved a modular form of reading a file and parsing them into parts of variables understandable by Matlab and calculate the required parameters.
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