Challenge

Project 1 - Parsing NASA thermodynamic data

AAkshay Pawar23 Apr 2022

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 - efficient 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 Gp , Hand's plots .

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

• Plots for 02 , 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 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 performing 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 / mal - X )

H = Enthalpy ( KJ / mol )

a ( ) = 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 + ( a2-7 ) + ( 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))`

Steps of main program:

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 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 the 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 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.

% 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);
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,500); 

% 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_name=(A{1}) ;            % To read the name of 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); 


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


% 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')); 
grid on


% 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')); 
grid on


% 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'));
grid on 

mkdir(species_name)
cd(species_name)
saveas(figure(1),'Specific Heat.jpg');
saveas(figure(2),'Entropy.jpg') ;
saveas(figure(3),'Enthalpy.jpg');
cd ..

atoms=['O','H','C','N','A'];
atomic_weight=[16 1 12 14 28];
MW=0;
for i=1:length(species_name)
    for j= 1:length(atoms)
    if strcmp(species_name(i),atoms(j))
        MW=MW+atomic_weight(j);
        dt=j;
    end
    end
    n=str2num (species_name(i));
    if n>1
       MW = MW+(atomic_weight(dt).*(n-1));
    end
end

sprintf('Molecular weight of % s:%f u',species_name,MW)



end

Functions to find specific heat

% Function to find Specific heat:

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


  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 related formula coefficient from 14 coefficients , Gas constant , Temperature and mid temperature .
Now we will create an condition using if loop and make the temperature less than and equal to mid temperature to specify lower temperature coefficient in the formula .
Then we will use else condition to specify coefficient of Higher temperature coefficient in the formula . • Then end the loop and function to Calculate Specific Heat.

Functions to find Entropy:

% Functions to find Entropy:

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

  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 related formula coefficient from 14 coefficients , Gas constant , Temperature and mid temperature .
Now we will create an condition using if loop and make the temperature less than and equal to mid temperature to specify lower temperature coefficient in the formula .
Then we will use else condition to specify coefficient of Higher temperature coefficient in the formula .
Then end the loop and function to calculate Entropy .

Functions to find Enthalpy

% Function to find enthalpy :

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

   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 related formula coefficient from 14 coefficients , Gas constant , Temperature and mid temperature .
Now we will create an condition using if loop and make the temperature less than and equal to mid temperature to specify lower temperature coefficient in the formula .
Then we will use else condition to specify coefficient of Higher temperature coefficient in the formula .
Then end the loop and function to calculate Enthalpy

Results: