Challenge

Project 1 - Parsing NASA thermodynamic data

TTivin C Reji18 Jul 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-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)))

Main Code

%% NASA Thermodynamic Data and calculating the molecular weight

clear all

close all

clc

% diary Results_NASA_Thermo_Data.txt;

% Getting the header info

f1=fopen('THERMO.dat','r');

header=fgetl(f1);

% Getting the temperature data

global_temp=fgetl(f1);

x=strsplit(global_temp);

global_temp_low=str2double(x{2});

global_temp_mid=str2double(x{3});

global_temp_high=str2double(x{4});

fgetl(f1);

% Reading the species

for i = 1:53

line1=strsplit(fgetl(f1),' ');

species_name=line1{1};

r = length(line1);

% getting local temp

local_low_temp=str2double(line1{r-3});

local_mid_temp=str2double(line1{r-1});

local_high_temp=str2double(line1{r-2});

%% Extracting the main coefficients from the data

% coefficient

line2=fgetl(f1);

line3=fgetl(f1);

line4=fgetl(f1);

a=strfind(line2,'E');

b=strfind(line3,'E');

c = strfind(line4,'E');

% For low temp

a1 = str2double(line2(1:a(1)+3));

a2 = str2double(line2(a(1)+4:a(2)+3));

a3 = str2double(line2(a(2)+4:a(3)+3));

a4 = str2double(line2(a(3)+4:a(4)+3));

a5 = str2double(line2(a(4)+4:a(5)+3));

a6 = str2double(line3(1:b(2)+3));

a7 = str2double(line3(b(1)+4:b(2)+3));

a8 = str2double(line3(b(2)+4:b(3)+3));

a9 = str2double(line3(b(3)+4:b(4)+3));

a10 = str2double(line3(b(4)+4:b(5)+3));

a11 = str2double(line4(1:c(1)+3));

a12 = str2double(line4(c(1)+4:c(2)+3));

a13 = str2double(line4(c(2)+4:c(3)+3));

a14 = str2double(line4(c(3)+4:c(4)+3));

% Applying universal gas constant

R = 8.314;

T = linspace(local_low_temp,local_high_temp,500);

% Calculation speicfic heat

[cp, h, s]=coeff(a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12,a13,a14,T,local_mid_temp,local_low_temp,local_high_temp);

%Calculation molecular weight

molecular_weight_cal = mole_wt(species_name);

k = sprintf('%s mol-wt=%f',species_name,molecular_weight_cal);

disp(k);

%MAKE DIRECTORY

mkdir(species_name)

cd(species_name)

%% Plotting the graph

%plotting between Temperature and specific heat

figure(1)

plot(T,cp,'linewidth',3,'color','r')

title('specific heat vs temperature',species_name);

xlabel('Temperature[k]')

ylabel('Specific Heat [kj/kg.k]')

m1 = 'Specific heat of %s';

m2 = species_name;

m3 = sprintf(m1,m2);

saveas(figure(1),sprintf('%s.png',m3))

% f = fullfile(species_name);

% cd(f);

% saveas(gcf,[pwd '/specific_heat vs temperature.jpg']);

% cd(file);

%plotting between Temperature and Enthalphy

figure(2)

plot(T,h,'linewidth',3,'color','b')

title('Enthalpy vs Temperature',species_name);

xlabel('Temperature[K]')

ylabel('Enthalpy[KJ]')

m4 = 'Enthalpy of %s';

m5 = species_name;

m6 = sprintf(m4,m5);

saveas(figure(2),sprintf('%s.png',m6))

%plotting between Temperature and Entropy

figure(3)

plot(T,s,'LineWidth',3,'color','c');

title('Entropy vs Temperature',species_name)

xlabel('Temperature[K]')

ylabel('Entropy[KJ/K]')

m7 = 'Entropy of %s';

m8 = species_name;

m9 = sprintf(m7,m8);

saveas(figure(3),sprintf('%s.png',m9))

% f = fullfile(species_name);

% cd(f);

% saveas(gcf,[pwd '/entropy vs temperature.jpg']);

% cd(file);

cd ..

end

fclose(f1)

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 code for Enthalpy, entropy and Specific heat

function [cp, h, s] = coeff(a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12,a13,a14,T,local_mid_temp,local_low_temp,local_high_temp)

% Given conditions

R = 8.314;

%for j = 1:length(T);

if T < local_mid_temp

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

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

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

else

cp=(a8+a9.*T+a10.*T.^2+a11.*T.^3+a12.*T.^4).*R;

h=(a8+(a9.*T)./2+(a10.*T.^2)./3+(a11.*T.^3)./4+(a12.*T.^4)./5+(a13./T)).*R.*T;

s=(a8.*log(T)+a9.*T+(a10.*T.^2)./2+(a11.*T.^3)./3+(a12.*T.^4)./4+a14).*R;

end

Function code for molecular weight

function [molecular_weight_cal] = mole_wt(species_name)

elements={'H','N','O','C','A'};

atomic_mass=[1 14 16 12 40];

mol_wt=0;

for i=1:length(species_name)

for j=1:length(elements)

if strcmp(species_name(i),elements(j))

mol_wt=mol_wt + atomic_mass(j);

m=j;

end

s = str2double(species_name(i));

if s>1

mol_wt=mol_wt+(atomic_mass(m)*(s-1));

end

molecular_weight_cal = mol_wt

fprintf('molecular_weight_cal of %s:- ',species_name)

fprintf('%d',molecular_weight_cal)

fprintf(' ')

fprintf('amu')

fprintf('\n')

end

Explanation

he first step is to clear all, close all, clc. The clear all command helps to clear the workspace. The close all command closes all figures and the clc command clears the command window.
The fopen command is used in reading mode to read the THERMO.dat file.
The temperature values are calculated by using strsplit,str2num commands.
Then the comment lines are stored in three variables i.e., line3, line4, line5.
The for loop is used to create an array that contains every line of the file.
Then the coefficients are founded by using the findstr, str2num.
Then the directory is created to save the plots in png format with the species name.
The cp, h, s functions are called to the main program which has been created separate script.
Then the plots are created between temperature and cp, s, h.
The saves are used to save the plots in png extension.
Finally, the mol_wt function is called for calculating the molecular weight of the species.
The fclose command is used to end the reading of the file.

Plots of CO2,N2,O2

Screenshot where all the plots of the species are saved

WORKSPACE SCREENSHOT SHOWING ALL THE VALUES

Errors were found

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

Conclusion

Using MATLAB code, the necessary coefficients required to evaluate various thermodynamic parameters for different species are extracted from NASA thermodynamic data file. The specific heat, enthalpy, and entropy for all the species are calculated and plotted against the local temperature range. The molecular weight is calculated for all the species.

Drive Link

https://drive.google.com/drive/folders/1_KT9MPZDnQhCiqJsX7N3LXu9vxvWq9Q5?usp=sharing

Project 1 - Parsing NASA thermodynamic data

Ship work like this
in your own course.

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Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.