Project 2 - Rankine cycle Simulator

The Rankine cycle is an idealized thermodynamic cycle describing the process by which certain heat engines, such as steam turbines or reciprocating steam engines, allow mechanical work to be extracted from a fluid as it moves between a heat source and heat sink.

 

There are four processes in the Rankine cycle. The states are identified by numbers (in brown) in the T–s diagram.

• Process 1–2: The working fluid is pumped from low to high pressure. As the fluid is a liquid at this stage, the pump requires little input energy. Process 1-2 is isentropic compression.
• Process 2–3: The high-pressure liquid enters a boiler, where it is heated at constant pressure by an external heat source to become a dry saturated vapour. The input energy required can be easily calculated graphically, using an enthalpy–entropy chart (h–s chart, or Mollier diagram), or numerically, using steam tables or software. Process 2-3 is constant pressure heat addition in boiler.
• Process 3–4: The dry saturated vapour expands through a turbine, generating power. This decreases the temperature and pressure of the vapour, and some condensation may occur. The output in this process can be easily calculated using the chart or tables noted above. Process 3-4 is isentropic expansion.
• Process 4–1: The wet vapour then enters a condenser, where it is condensed at a constant pressure to become a saturated liquid. Process 4-1 is constant pressure heat rejection in condenser.

EXPLANATION OF CODE:

• We start the program by reading about the Rankine cycle and the given data of the XSteam.
• First, we need input data of pressure at turbine inlet, the temperature at turbine inlet, the pressure at condenser inlets.
• Now we return the pressure and the temperature, by using the above-given data and XSteam.
• With this, we further simplify using the same data and the study over the Rankine cycle.
• By all the study we calculate saturated liquid and saturated vapor through the plots.
• Then we calculate the total work, work done on the turbine, and work done on the pump.
• We also calculate the efficiency and the specific steam consumption.
• After the 4th stage of variation, we observe the plot by extracting the temperature enthalpy and entropy.
• Plotting graph of temperature vs enthalpy and enthalpy vs entropy while giving them line color and linewidth
• As the input changes the graph change. 
• And the results will be displayed on the window command

close all 
clear all
clc

disp(' Rankine cycle Simulator');
disp('1-2 is Constant pressure heat addition in the boiler');
disp('2-3 is Isentropic Expansion in the Turbine');
disp('3-4 is Constant pressure heat removal in the Condenser');
disp('4-1 is Isentropic compression in the pump');

pl = input('nvalue of pressure at turbine inlet in bar, P1 = ');
T1 = input('nvalue of temperature at turbine inlet in degree.C, T1 = ');
p2 = input('nvalue of pressure at condenser inletin bar, P2 = ');

% At State 1
h1 = XSteam('h_pT', pl, T1);
s1 = XSteam('s_pT',pl, T1);

%0 At State 2

s2 = s1;
sf2= XSteam('sL_P', p2);
sg2 = XSteam('sv_p', p2);
x2 = (s2-sf2)/(sg2-sf2);
hf2 = XSteam('hL_P', p2);
hg2 = XSteam('hv_p', p2);
h2 = hf2 + (x2*(hg2-hf2));

% At State 3

p3 = p2;
s3 = XSteam('sL_p', p3);
h3 = XSteam('hL_p', p3);

% At State 4

s4 = s3;
p4 = pl;

% Work done by turbine

Wt = h1 - h2;

% Work done to run pump

v3 = XSteam('vL_p', p3);
Wp = v3*(p4 - p3)*100;
h4 = h3 + Wp;

%Network

Wnet = Wt - Wp;

% Heat into the system 
Qin = h1 - h4;

% Heat out of the system 
Qout = h2 - h3;

%Thermal efficiency 
thermal_eff = (Wnet/Qin)*100;

% Specific Steam Consumption
%SSC = mass flow rate/power
SSC = (3600/Wnet);

% Back Work ratio

BW = (Wp/Wt);

% Calculation of Temperatures at the state points

T3 = XSteam('Tsat_p', p3);

T2 = T3;


Cp4 = XSteam('Cp_ps', p4, s4);
CV4 = XSteam('Cv_ps', p4, s4);
k = Cp4/CV4;
T4 = T3/((p3/p4)^((k-1)/k));

%Calculating Temperature, Entropy and Enthalpy at the vapour and liquid line for plotting

T6 = XSteam('Tsat_p', pl);
s5 = XSteam('sL_p', pl);
s6 = XSteam('sV_p', pl);
h5 = XSteam('hL_p', pl);
h6 = XSteam('hv_p', pl);
T5 = T6;

%Plotting the saturation curve 

T = linspace(1,375,1000);
for i = 1: length(T)

sf(i) = XSteam('sL_T', T(i));
sg(i) = XSteam('sV_T', T(i));
hf(i) = XSteam('hL_T', T(i));
hg(i) = XSteam('hV_T', T(i));

end

% Plotting T-s diagram
figure(1)
hold on
plot(sf, T,'r','linewidth',1)
plot(sg, T,'r','linewidth',1)
plot([s1 s2], [T1 T2],'b','linewidth', 2)
plot([s2 s3], [T2 T3],'b','linewidth', 2)
plot([s3 s4], [T3 T4],'b','linewidth', 2)
plot([s4 s5], [T4 T5],'b','linewidth', 2)
plot([s5 s6], [T5 T6],'b','linewidth', 2)
sc1 = linspace(s6, s1, 1000);

for l = 1: length(sc1)
    
Tc1(l) = XSteam('T_ps', pl, sc1(l));

end

plot (sc1, Tc1,'b','linewidth', 2)
text(s1+0.1, T1,'1')
text(s2+0.1, T2,'2')
text(s3, T3-20,'3')
text(s4, T4+20,'4')
title('Temp vs Entropy plot')
xlabel('Entropy,S (Kj/kgk)')
ylabel('Temperature (degree C)')
legend('Saturation curve')

%plotting h-s diagram
figure(2)
hold on
plot(sf, hf, 'k','linewidth', 1)
plot(sg, hg,'k', 'linewidth', 1)
plot([s1 s2], [h1 h2], 'r', 'linewidth', 2)
plot([s2 s3], [h2 h3], 'r', 'linewidth', 2)
plot([s3 s4], [h3 h4], 'r', 'linewidth', 2)

hc = linspace(h4, h5, 100);
for r = 1:length(hc)
sch(r) = XSteam('s_ph', pl, hc(r));
end

plot(sch, hc, 'r', 'linewidth', 2)
plot([s5 s6], [h5 h6], 'r', 'linewidth', 2)

for m = 1: length(sc1)
    hc1(m) = XSteam('h_ps', pl, sc1(m));
end

plot(sc1, hc1,'r','linewidth', 2)
text(s1+0.1,h1, '1')
text(s2+0.1,h2, '2')
text(s3, h3-100, '3')
text(s4, h4 +200,'4')

title('Enthalpy vs Entropy plot')
xlabel('Entropy, S (KJ/kg)')
ylabel('Enthalpy, H (KJ/kg)')
legend('Saturation curve', 'location', 'northwest')

% Displaying the Results in the Command Window:

disp('Results');
pl = pl;
T1 = T1;
p2 = p2;
disp('At stage point 1')
n1 = sprintf('P1 is %.3f bar',pl);
disp(n1);
n2 = sprintf('T1 is %.3f C',T1);
disp(n2);
n3 = sprintf('h1 is %.3f kJ/kg',h1);
disp(n3);
n4 = sprintf('s1 is %.3f k3/kgK', s1);
disp(n4);
disp('At stage point 2');
n11 = sprintf('P2 is %.3f bar',p2);
disp(12);
n21 = sprintf('T2 is %.3f C',T2);
disp(n21);
n31 = sprintf('h2 is %.3f k3/kg',h2);
disp(n31);
n41 = sprintf('s2 is %.3f kJ/kgk', s2);
disp(n41);
disp('At stage point 3');
n12 = sprintf('P3 is %.3f bar', p3);
disp(n12);
n22 = sprintf('T3 is %.3f C', T3);
disp(n22);
n32 = sprintf('h3 is %.3f kJ/kg',h3);
disp(n32)
n42 = sprintf('s3 is %.3f k/kgK', s3);
disp(n42);
disp('At stage point 4');
n13 = sprintf('P4 is %.3f bar',p4);
disp(n13);
n23 = sprintf('T4 is %.3f C', T4);
disp(n23);
n33 = sprintf('h4 is %.3f k3/kg',h4);
disp(n33);
n43 = sprintf('s4 is %.3f kJ/kgK',s4);
disp(n43);
n14 = sprintf('Wt is %.3f k3/kg',Wt);
disp(n14);
n15 = sprintf('Wp is %.3f kJ/kg',Wp);
disp(n15);
n16 = sprintf('Wnet is %.3f k3/kg',Wnet);
disp(n16);
n17 = sprintf('Thermal efficiency is %.2f Percent', thermal_eff);
disp(n17);
n18 = sprintf('SSC is %.2f kg/kWh',SSC);
disp(n18);
n19 = sprintf('Back work ratio is %.3f',BW);
disp(n19);