Project 1 - Parsing NASA thermodynamic data
AIM:
To write a program in matlab to parse the NASA thermodynamic data file and then calculate the thermodynamic properties of various gas species.
OBJECTIVE:
To write a function that extracts the 14 co-efficient and calculates the enthalpy ,entropy and specific heats for all species in the data file.
Calculating the molecular weight of each species and displaying it in command window.
Plotting cp, enthalpy and entropy for local temperature range specific for each species.
Save the plot as images with appropriate names and dump them in separate folders for each species with suitable name.
INTRODUCTION:
PARSING DATA:
Parsing means to make something understandable. For programming this means to convert information represented in one form into another form that's easier to work with. This is done by partially analysing the data, understanding its underlying structure (by making some assumptions based on what you're expecting to see), and then explicitly representing that structure in the code. 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.
EQUATIONS:
The equations that we are going to use in the Functions to calculate cp, H,S are:
Where,
Cp=specific heat
R =molar gas constant T=temperature S=Entropy
H=Enthalpy a=coefficients
BODY OF THE CONTENT:
Code for calling function Specific_heat:
function Cp = Specific_heat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,T,R,global_midtemp)
%calculating specific_heat for higher and lower temperature respectively if(T>= global_midtemp)
Cp=R*(a1+(a2*T)+(a3*(T).^2)+(a4*(T).^3)+(a5*(T).^4)); else
Cp=R*(a8+(a9*T)+(a10*(T).^2)+(a11*(T).^3)+(a12*(T).^4)); end
end
Code for calling function Enthalpy:
function H = Enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,T,R,global_midtemp)
%calculating enthalpy for higher and lower temperature respectively if(T>=global_midtemp)
H=R*((a1*T)+((a2*(T).^2)/2)+((a3*(T).^3)/3)+((a4*(T).^4)/4)+((a5*(T).^5)/5)+a6);
else
H=R*((a8*T)+((a9*(T).^2)/2)+((a10*(T).^3)/3)+((a11*(T).^4)/4)+((a12*(T).^5)/5)+a13);
end
end
Code for calling function Entropy:
function S=Entropy(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,T,R,global_midtemp)
%calculating entropy for higher and lower temperature respectively if(T>= global_midtemp)
S=R*(a1.*log(T)+(a2*T)+((a3*(T).^2)/2)+((a4*(T).^3)/3)+((a5*(T).^4)/5)+a7); else
S=R*(a8.*log(T)+(a9*T)+((a10*(T).^2)/2)+((a11*(T).^3)/3)+((a12*(T).^4)/4)); end
end
Code for calculating molecular weight by calling function wt:
function Molecular_weight=wt(species_name)
Elements=['H' 'C' 'O' 'N' 'A' 'S']; Atomic_weight =[1 12 16 14 40 32]; species=upper(species_name)
Molecular_weight=0;
for i=1:length(species) for j=1:length(Elements)
if strcmp(species(i),Elements(j))
Molecular_weight=Molecular_weight+Atomic_weight(j);
k=j;
else
n=str2double(species(i));
if (n>1)
Molecular_weight=Molecular_weight+Atomic_weight(k)*(n-1);
break
end
end
end
end
end
MAIN CODE:
clear all close all clc
%R=molar gas constant R=8.314;
%syntax to open the file THERMO.dat
f1=fopen('THERMO.dat','r')
%To read lines l1=fgetl(f1); l2=fgetl(f1); value=strsplit(l2,' ');
%To get global temperatures from file in number form
global_lowtemp=str2num(value{2})
global_midtemp=str2num(value{3})
global_hightemp=str2num(value{4})
%temperature range T=linspace(global_lowtemp,global_hightemp,1000);
%skipping these 3 lines l3=fgetl(f1); l4=fgetl(f1); l5=fgetl(f1);
%Reading species ,calcuating cp,h,s and plotting for i=1:53
tline=fgetl(f1);
A=strsplit(tline,' ');
name_of_species=(A{1});
lowtemp= str2num(A{end-3});
midtemp=str2num(A{end-2});
hightemp=str2num(A{end-1});
%Finding 7 higher coefficients and 7 lower coefficients
tline1=fgetl(f1);
a=findstr(tline1,'E');
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);
a=findstr(tline2,'E');
a6=tline2(1:a(1)+3);
a6=str2num(a6);
a7=tline2(a(1)+4:a(2)+3);
a7=str2num(a7);
a8=tline2(a(2)+4:a(3)+3);
a8=str2num(a8);
a9=tline2(a(3)+4:a(4)+3);
a9=str2num(a9);
a10=tline2(a(4)+4:a(5)+3):
a10=str2num(a10);
tline3=fgetl(f1);
a=findstr(tline3,'E');
a11=tline3(1:a(1)+3);
a11=str2num(a11);
a12=tline3(a(1)+4:a(2)+3);
a12=str2num(a12);
a13=tline3(a(2)+4:a(3)+3);
a13=str2num(a13);
a14=tline3(a(3)+4:a(4)+3);
a14=str2num(a14);
%calculate specific heat(cp),Enthalpy(H),Entropy(S)
Cp=Specific_heat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,T,R,global_midtemp);
H=Enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,T,R,global_midtemp);
S=Entropy(a1,a2,a3,a4,a5,a7,a8,a9,a10,a11,a12,a14,T,R,global_midtemp);
%calculating molecular weight and printing it.
Molecular_weight=wt(name_of_species);
fprintf('molecular weight of %s= %fn',name_of_species,Molecular_weight);
%PLOTTING CP,H,T
cd('C:UsershhhDesktopmatlabNASA FILES')
%creating the folder
mkdir(name_of_species);
cd(name_of_species);
%plotting T vs cp
figure(1)
plot(T,Cp,'linewidth',5,'color','r')
xlabel('Temperature(T)')
ylabel('Specific heat(cp)')
grid on
title(name_of_species)
saveas(figure(1),'specific heat.jpg');
%Plotting T vs H
figure(2)
plot(T,H,'linewidth',5,'color','b')
xlabel('Temperature(T)')
ylabel('Enthalpy(H)')
grid on
title(name_of_species)
saveas(figure(2),'Enthalpy.jpg');
%Plotting T vs S
figure(3)
plot(T,S,'linewidth',5,'color','y')
xlabel('Temperature(T)')
ylabel('Entropy(S)')
grid on
title(name_of_species)
saveas(figure(3),'Entropy.jpg');
cd('C:UsershhhDocumentsMATLABnasa files')
end
Expalanation for the code:
Initially the value of ‘R’ is being defined.
Then we use a command to open the file ‘THERMO.dat’ .
Further we use the ‘fgetl’ to start reading the lines and after reading the first two lines, from the second line converting the strings to numbers and assigning global (low,mid and high) temperatures.
Then we have written a command to get the temperature range for calculation and plotting purpose.
Then again using the fgetl command to go to thel next 3 lines and skipping it.
Then we use a for loop to get 53 species and their temperatures (low, mid, high) and the 14 coefficients.
In the for loop we again use the fgetl command and then the next line is read and from that line the species name, the three local temperatures are read and stored.
Then we use fgetl command to go to further line and get the first 7 coefficients and store them. Similarly using the fgetl command we move to the next two lines and get the remaining coefficients.
Then after getting the 14 coefficients, we use these coefficients and by calling the functions we calculate cp,H,S.
Further we use the Molecular weight function and calculate molecular weight for that species.
Further I have used a command to change the directory so that I can save the files at a particular location.After changing the directory I have used ‘mkdir' to create a new folder with the name of the current species and then a ‘cd’ command to make mkdir as the current directory.
Then further we use plot command to plot temperature vs (cp,enthalpy,entropy) .
In this plotting we use the figure command to get the three different plots and saveas command to save the figures in the
Then again we change our directory to again start the loop. So the loop continues to function till we get all the 53 species and then gets terminated.
OUTPUTS:
Plots for oxygen(o2) :
Plots for nitrogen(N2) :
Plots for carbon dioxide(co2) :
Screenshot of the folder:
Molecular weights:
CONCLUSION:
So here we were able to parse the data from the THERMO.dat file. Then using this data we were able to calculate the thermodynamic properties and also make plots for these properties with respect to the temperature.