rankine cycle

clear all
close all
clc

disp(\'RANKINE CYCLE\');
disp(\'1-2 : isentropic expansion\')
disp(\'2-3 : constant pressure heat rejection\')
disp(\'3-4 : isentropic compression\')
disp(\'4-1 : constant pressure heat addition\')
%input parameters
t1 = 400;
p1 = 30;
p2 = 0.05;
%---pt 1---
h1 = XSteam(\'h_pt\',p1,t1);
s1 = XSteam(\'s_pt\',p1,t1);
ts1 = XSteam(\'Tsat_p\',p1);
sf1 = XSteam(\'sL_p\',p1);
sg1 = XSteam(\'sV_p\',p1);
hf1 = XSteam(\'hL_p\',p1);
hg1 = XSteam(\'hV_p\',p1);
%exit parameters for turbine
s2 = s1;
sf2 = XSteam(\'sL_p\',p2);
sg2 = XSteam(\'sV_p\',p2);
sfg2 = sg2 - sf2;
hf2 = XSteam(\'hL_p\',p2);
hg2 = XSteam(\'hV_p\',p2);
hfg2 = hg2 - hf2;
ts2 = XSteam(\'Tsat_p\',p2);
%specific heat capacity for vapour
cpv1 = XSteam(\'CpV_p\',p1);
cpv2 = XSteam(\'CpV_p\',p2);
cvv1 = XSteam(\'CvV_p\',p1);
cvv2 = XSteam(\'CvV_p\',p2);
%specific heat capacity for liquid
cpl1 = XSteam(\'CpL_p\',p1);
cpl2 = XSteam(\'CpL_p\',p2);
cvl1 = XSteam(\'CvL_p\',p1);
cvl2 = XSteam(\'CvL_p\',p2);

%---pt 2---
         
%dryness factor
x = (s2 - sf2)/sfg2;             
%temperature at exit
if x < 1
    t2 = ts2+273;
else
    t2 = ts2*exp((s2-sg2)/cpv2);
end
t2 = t2-273;
%enthalpy at exit 
if x < 1
    h2 = hf2 + (x*hfg2);            
else
    h2 = hg2+(cpv2(t2-ts2));
end
%---pt 3---                
p3 = p2; %constant pressure heat rejection

t3 = ts2;

h3 = hf2;

s3 = sf2;

ts3 = XSteam(\'Tsat_p\',p3);
%specific volume
v3 = XSteam(\'vL_p\',p3); 
%---pt 4---  
p4 = p1;

s4 = s3;

sf4 = XSteam(\'sL_p\',p4);

ts4 = XSteam(\'Tsat_p\',p4);

% workdone by the pump   
wp = v3*(p4-p3)*100 ; 
% workdone by the turbine
wt = h1 - h2;

h4 = wp + h3;
%to find super heated temperature
t4 = (exp((s4-sf4)/cpv1))*ts4;
%net work output
wnet = wt - wp;
%heat input
qin = h1 - h4;
%Thermal efficiency :
efficiency = wnet*100 / qin;

%saturation line value
t = linspace(0,500,500);%temperature = t
for i = 1:length(t)
    hsl(i) = XSteam(\'hL_T\',t(i));
    hsv(i) = XSteam(\'hV_T\',t(i));
    ssl(i) = XSteam(\'sL_T\',t(i));
    ssv(i) = XSteam(\'sV_T\',t(i));
end

% plotting t-s graph
figure(1)
title(\'t-s diagram\')
hold on
plot(ssl, t, \'R\', \'linestyle\', \'--\')
plot(ssv, t, \'R\', \'linestyle\', \'--\')
plot([s1,s2],[t1,t2],\'g\')
plot([s2,s3],[t2,t3],\'g\')
plot([s3,s4],[t3,t4],\'g\')
plot([s4,sf1],[t4,ts1],\'g\')
plot([sf1,sg1],[ts1,ts1],\'g\')
plot([sg1,s1],[ts1,t1],\'g\')
text(s1,t1,\'1\')
text(s2,t2,\'2\')
text(s3,t3,\'3\')
text(s4,t4,\'4\')
hold off
xlabel(\'entropy(s) in kj/kgk ----->\')
ylabel(\'temperature(t) in degree celsius----->\')

% plotting h-s graph
figure(2)
title(\'h-s diagram\')
hold on
plot(ssl, hsl, \'R\', \'linestyle\', \'--\')
plot(ssv, hsv, \'R\', \'linestyle\', \'--\')
plot([s1,s2],[h1,h2],\'g\')
plot([s2,s3],[h2,h3],\'g\')
plot([s3,s4],[h3,h4],\'g\')
plot([s4,s1],[h4,h1],\'g\')
text(s1,h1,\'1\')
text(s2,h2,\'2\')
text(s3,h3,\'3 4\')
hold off
xlabel(\'entropy(s) in kj/kgk ----->\')
ylabel(\'enthalpy(h) in kj/kg----->\')
disp(\'-------------------------------------\');
fprintf(\'Thermal efficiency :%f\',efficiency); disp(\'%\');
fprintf(\'Net work output :%f kj/kg\\n\',wnet);
fprintf(\'tubrine output :%f kj/kg\\n\',wt);
fprintf(\'pump input :%f kj/kg\\n\',wp);disp(\'----------------------------\');
disp(\'At state point 1\');
fprintf(\'h1 : %f kj/kg\\n\',h1)
fprintf(\'p1 : %f bar\\n\',p1);
fprintf(\'t1 : %f celsius\\n\',t1);
fprintf(\'s1 : %f kj/kgk\\n\',s1);disp(\'------------------------\');
disp(\'At state point 2\');
fprintf(\'h2 : %f kj/kg\\n\',h2)
fprintf(\'p2 : %f bar\\n\',p2);
fprintf(\'t2 : %f celsius\\n\',t2);
fprintf(\'s2 : %f kj/kgk\\n\',s2);disp(\'------------------------\');
disp(\'At state point 3\');
fprintf(\'h3 : %f kj/kg\\n\',h3)
fprintf(\'p3 : %f bar\\n\',p3);
fprintf(\'t3 : %f celsius\\n\',t3);
fprintf(\'s3 : %f kj/kgk\\n\',s3);disp(\'------------------------\');
disp(\'At state point 4\');
fprintf(\'h4 : %f kj/kg\\n\',h4)
fprintf(\'p4 : %f bar\\n\',p4);
fprintf(\'t4 : %f celsius\\n\',t4);
fprintf(\'s4 : %f kj/kgk\\n\',s4);disp(\'------------------------\');

Saturation curve:

source: https://www.ecourses.ou.edu/cgi-bin/ebook.cgi?doc=&topic=th&chap_sec=02.2&page=theory

The water vaporization process can also be described in P-v diagram. The method of creation the P-v Diagram is much like the method for the T-v diagram. By considering the piston-cylinder device again, the temperature keeps constant by heat transfer. The pressure is changed by removing the weight. Like the process in previous section, the water will become saturated liquid, saturated mixture, saturated vapor and superheated vapor if enough heat added. The process is repeated under several different temperatures and plot them in a P-v diagram. By connecting all the saturated liquid states under different temperatures, one can create the saturated liquid line and connecting all the saturated vapor states, one can create the saturated vapor line on the P-v diagram. There are three regions on the P-v diagram: subcooled liquid region, saturated liquid-vapor region, and superheated vapor region.

assigning process 4-1-2-3 as 1-2-3-4 for the above picture for convenient:

 1-2 isentropic expansion which means assuming there are no losses in expansion & converting the complete heat and pressure to work output in the form of mechanical energy by the turbine.

2-3  constant pressure heat rejection heat is removed from the steam using condensor.

3-4 isentropic compression where the pump compresses the condensate to the high-pressure side.

4-1 constant pressure heat addition where the heat is given and the pressure is maintained by the heat addition.

the working element can be steam.

heat addition can be from burning coal, nuclear fission.

Power depends on the temperature difference between a heat source and a cold source.

Error faced:

since Matlab is case sensitive 

instead using temperature in degree celsius I used in kelvin I came to know only when I plot.

in fprintf I came to know that to add \\n at the end [\'fprintf(\'h3 : %f kj/kg\\n\',h3)\'] so that to get the result in orderly