Project

Parsing NASA Thermodynamic Data

MMudit Verma19 Aug 2020

AIM:- Write a code in Matlab to parse the NASA thermodynamic data file and then calculate thermodynamic properties of various gas species.

OBJECTIVE:-

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.
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. All these should be generated automatically.
The main program that you will submit 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.

File Parsing:-

Parsing, syntax analysis, or syntactic analysis is the process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar. The term parsing comes from Latin pars (orationis), meaning part (of speech).Within computational linguistics the term is used to refer to the formal analysis by a computer of a sentence or other string of words into its constituents, resulting in a parse tree showing their syntactic relation to each other, which may also contain semantic and other information.Some parsing algorithms may generate a parse forest or list of parse trees for a syntactically ambiguous input.

Parsing a file means reading in a data stream of some sort and building an in memory model of the semantic content of that data. This aims at facilitating perfoming some kind of transformation on the data.

NASA Thermodynamic File:-

NASA thermodynamics file which is THERMO.dat file in which there are temperature range and 53 species are given in these data and each species contains 14 coefficients and temperature ranges and we have to parse these 14 coefficients to find Specific heat, Entropy and Enthalpy using formula as:-

where,

R = Universal Gas constant

T = Temperature

Cp = Specific heat (KJ)

S = Entropy(KJ/mol-K)

H = Enthalpy(KJ/mol)

a(i) = Coefficients where, i = 1 to 14

Specific Heat:-

The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. The relationship between heat and temperature change is usually expressed in the form shown below where c is the specific heat.

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

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.

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

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 contained so as to prevent mass transfer, for processes at constant pressure, the heat absorbed or released equals the change in enthalpy.

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

CODE:-

Main code:-

clear all
close all
clc

%Input
R=8.314; % Gas Constant

% Reading data file
% open file and reading THERMO.dat file
f1 = fopen('THERMO.dat','r')
get = fgetl(f1);

% Now Reading Temperature from this file
temp = fgetl(f1);

%spliting
s = strsplit(temp);

% converting strings cells into numbers
templow = str2num(s{2});
tempmid = str2num(s{3});
temphigh = str2num(s{4});

% Temperature Range
T = linspace(templow,temphigh,1000);

%Skipping comment lines
for i=1:3
    get=fgetl(f1);
end

% Reading the Species
for j=1:53
    tline=fgetl(f1);  
    
   A=strsplit(tline,' ');  % spliting into cell array
    species =  (A{1});         % To read the name of the species
   
     % Converting string to number                         
    lowtemp = str2num(A{end-3});  
    midtemp = str2num(A{end-2});
    hightemp = str2num(A{end-1});
    
    
    tline1 = fgetl(f1);   % getting next line
    a = strfind(tline1,'E');  % Finding the string E
    
    % Finding First 7 higher and second 7 lower coefficients
    %Finding Higher coefficients
    a1 = tline1(1:a(1)+3);
    a1 = str2num(a1);
    a2 = tline1(a(1)+4:a(2)+3);
    a2 = str2num(a2);
    a3 = tline1(a(2)+4:a(3)+3);
    a3 = str2num(a3);
    a4 = tline1(a(3)+4:a(4)+3);
    a4 = str2num(a4);
    a5 = tline1(a(4)+4:a(5)+3);
    a5 = str2num(a5);
    
    tline2 = fgetl(f1);
    b = strfind(tline2,'E');
    a6 = tline2(1:b(1)+3);
    a6 = str2num(a6);
    a7 = tline2(b(1)+4:b(2)+3);
    a7 = str2num(a7);
    
    % Finding Lower coefficients
    a8 = tline2(b(2)+4:b(3)+3);
    a8 = str2num(a8);
    a9 = tline2(b(3)+4:b(4)+3);
    a9 = str2num(a9);
    a10 = tline2(b(4)+4:b(5)+3);
    a10 = str2num(a10);
    
    tline3 = fgetl(f1);
    c = strfind(tline3,'E');
    a11 = tline3(1:c(1)+3);
    a11 = str2num(a11);
    a12 = tline3(c(1)+4:c(2)+3);
    a12 = str2num(a12);
    a13 = tline3(c(2)+4:c(3)+3);
    a13 = str2num(a13);
    a14 = tline3(c(3)+4:c(4)+3);
    a14 = str2num(a14);
    
    % calculate specific heat
    Cp = Specific_heat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,T,R,tempmid);
    
    % calculate Entropy 
    S = Entropy(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,T,R,tempmid);
    
    % claculate Enthalpy
    H = Enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,T,R,tempmid);
    
    % Calculate Molecular weight of the Species
    W = Molecular_weight(species);
    
    % writing molecular weight file
    MW_file = fopen('Molecular Weight.txt','w');
    fprintf(MW_file,'Molecular weight of %s is %d ',species,W); 
    fclose(MW_file);   % Closing the file
    
    %Plotting Cp, H and S with Temperature
    % Saving in a folder
    cd('C:/Users/Mudit Verma/Desktop/skill lync/Species')  % changing directory
    mkdir(species);  %creating directory
    cd(species);
    
    
    % Plot 1 Cp vs T
    figure(1)
    plot(T,Cp,'linewidth',2,'color','b');
    xlabel('Temperature(K)');
    ylabel('Specific Heat(KJ)');
    title(sprintf('Specific heat vs Temperature range of %s',species));
    grid on
    saveas(figure(1),'Specific Heat.jpg');
    
    % Plot 2 S vs T
    figure(2)
    plot(T,S,'linewidth',2,'color','r');
    xlabel('Temperature');
    ylabel('Entropy(KJ/mol-K)');
    title(sprintf('Entropy vs Temperature range of %s',species));
    grid on
    saveas(figure(2),'Entropy.jpg');
    
    % Plot 3 Cp vs T
    figure(3)
    plot(T,H,'linewidth',2,'color','g');
    xlabel('Temperature');
    ylabel('Enthalpy(KJ/mol)');
    title(sprintf('Enthalpy vs Temperature range of %s',species));
    grid on
    saveas(figure(3),'Enthalpy.jpg');
    
    cd('C:/Users/Mudit Verma/Desktop/skill lync')  %Changing directory to Original matlab path
    
    % Molecular weight
    W =  Molecular_weight(species)
   
end

STEPS:-

Firstly, we will Input the parameter R and we will open a file THERMO.dat file and reading this file using fopen command.
Then, we will read first THERMO using fgetl command and then we read temperature file and we will split the temperatures using strsplit command to convert it into cell array and then we will convert this string to number using str2num command to find low, high and mid temperatures.
Then we will assign temperature range using linspace command. Then we run loop to skip command lines the data file using fgetl command inside the loop.
Now, we will run the loop to find 53 element in the data file by assigning fgetl command and then spliting into the cell array to find the species line and then find the species name and then find the number of the temperatures in the species line.
Then we read the new line. In order to read the coefficient in the data file we will first find the 'E' string using strfind command to find before and after numbers of the coefficients then we will find remaining 14 coefficients and convert them to numbers from strings.
Out of which we will find first 7 Coefficients which are for Higher temperature and then Second 7 Coefficients which are for Lower temperature.
Now we will specify Specific heat Cp, Entropy S, Enthalpy H functions to find these parameters using these 14 coefficients for Lower and higher Temperature. then we will specify molecular weight W function to find the Molecular weight of the different species.
Now we will write the Molecular weight.txt file and fprintf all the molecular weights of the species. and then close the txt file using fclose command.
Now we change the directory using cd command and then creating directory folder where we have to save our files using mkdir command and then we will change the directory to this created folder.
Now, we will plot Specific heat, Entropy and Enthalpy with the Temperature for different species. We we will use scanf command to in the title command to create different species title.
Then we will use saveas command to save the plots of different species in the directory folder. Now we will change the directory to which our main code file runs in the MATLAB.

Function to find Specific Heat :-

function Cp = Specific_heat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,T,R,tempmid)

    % calculating specific heat
    % calculating specific heat for higher and lower temperature repectively.

    if (T <= tempmid)
        Cp = R*(a8 + (a9*T) + (a10*(T).^2) + (a11*(T).^3) + (a12*(T).^4));
    else
        Cp = R*(a1 + (a2*T) + (a3*(T).^2) + (a4*(T).^3) + (a5*(T).^4));
    end
end

STEPS :-

Now we will find the Specific heat by creating Specific heat function and assigning its relted formula coefficent from 14 coefficients, Gas constant, Temperature and mid temperature.
Now we will creatre an condition using if loop and make the temperature less than and equal to mid temperature to specify lower temperature coefficent in the formula.
Then we will use else condition to specify coefficient of Higher temperature coefficent in the formula.
Then end the loop and function to calculate Specific Heat.

Function to find Entropy:-

function S = Entropy(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,T,R,tempmid)

    % calculating entropy
    % calculating entropy for higher and lower temperature repectively.

    if (T <= tempmid)
        S = R*(a8.*log(T) + (a9*T) + ((a10*(T).^2)/2) + ((a11*(T).^3)/3) + ((a12*(T).^4)/4) + a14);
    else
        S = R*(a1.*log(T) + (a2*T) + ((a3*(T).^2)/2) + ((a4*(T).^3)/3) + ((a5*(T).^4)/4) + a7);
    
    end
end

STEPS :-

Now we will find the Entropy by creating Entropy function and assigning its relted formula coefficent from 14 coefficients, Gas constant, Temperature and mid temperature.
Now we will creatre an condition using if loop and make the temperature less than and equal to mid temperature to specify lower temperature coefficent in the formula.
Then we will use else condition to specify coefficient of Higher temperature coefficent in the formula.
Then end the loop and function to calculate Entropy.

Function to find Enthalpy :-

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

    % calculating enthalpy
    % calculating enthalpy for higher and lower temperature repectively.

    if (T <= tempmid)
        H = R*T.*(a8 + ((a9*T)/2) + ((a10*(T).^2)/3) + ((a11*(T).^3)/4) + ((a12*(T).^4)/5) 
        + ((a13./T)));
    else
        H = R*T.*(a1 + ((a2*T)/2) + ((a3*(T).^2)/3) + ((a4*(T).^3)/4) + ((a5*(T).^4)/5) + 
        ((a6./T)));
    end
end

STEPS :-

Now we will find the Enthalpy by creating Enthalpy function and assigning its relted formula coefficent from 14 coefficients, Gas constant, Temperature and mid temperature.
Now we will creatre an condition using if loop and make the temperature less than and equal to mid temperature to specify lower temperature coefficent in the formula.
Then we will use else condition to specify coefficient of Higher temperature coefficent in the formula.
Then end the loop and function to calculate Enthalpy.

Function to find Molecular weight of the different Species :-

function W = Molecular_weight(species)

    % Defining Atomic name of the species
    atomic_name = ['H','C','O','N','Ar'];
    
    % Defining Atomic masses of main species
    atomic_weight = [1.008 12.011 15.999 14.007 39.948];
    
    W=0;  % Molecular weight starting range
    
    for i=1:length(species)   % Loop runs to the length of the species
        for j=1:length(atomic_name)  % Loop runs to the length of the atomic names
            if strcmp(species(i), atomic_name(j))  %function to compare 2 strings
                W = W + atomic_weight(j);
                position = j;
            end
        end
        n = str2num(species);   % Now we will find if there is more element in the species then incrementing atomic weight of the species
        
        if n>1
            W = W + atomic_weight(position)*(n-1);
        end
    end
    
    fprintf('Molecular Weight of %s :- ',species);
    fprintf('%f',W);
    disp(' ')
end

STEPS :-

Firstly we create an Molecular_weight functionW and assigning species input to that.
Then define the main element of all 53 species in an array atomic_name that are :- 'H','C','O','N','Ar'.
Then by taking above main elements we will create there atomic_wieght array from any source like internet that are :- 1.008 12.011 15.999 14.007 39.948.
Then we will assign molecular starting range W To zero and then create an for loop condition which runs to the length of the species and an another nested for loop is created which runs to the length of the string atomic_name.
Then we will create an condition using if condition and use strcmp command to compare the species and atomic_name strings to calculate molecular masses if by comparison both string found same then we will assign its molecular weight.
Now, we will string to the number using str2num command assign to n. Then we run an condition of if loop to find weather the species contains more than one element if there are more then 1 elements that is n>1 then we will increment the atomic weight by the multiplication of position and n-1 to the atomic_weight array.
Then we will print the Molecular weight using fprintf command and display it using disp command.

ERRORS :-

This error is faced due to invalid syntax I have assigned for assigning the cell arrays by using beckets ().

By assigning curly bracket this error got vanished which is the right syntax.

This error is correctes by using correct syntax STR2NUM command to convert string into number in except using STR2DOUBLE command.

Using wrong syntax inside the strcmp command for comparing the strings by using atomic_weight array in except to tha atomic_name string and assining wrong inputs.