Project 2 - Rankine cycle Simulator

Rankine cycle:-

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 a heat sink.

Heat energy is supplied to the system via a boiler where the working fluid (typically water) is converted to a high-pressure gaseous state (steam) in order to turn a turbine. After passing over the turbine the fluid is allowed to condense back into a liquid state as waste heat energy is rejected before being returned to the boiler, completing the cycle.

Processes in the Rankine cycle:-

The Rankine cycle is the ideal cycle for vapor power plants; it includes the following four
reversible processes:

Process 1–2 Isentropic Expansion: The dry saturated vapour expands through a turbine, generating power. This decreases the temperature and pressure of the vapour, and some condensation may occur.

Process 2–3 Constant pressure heat rejection: The wet vapour then enters a condenser, where it is condensed at a constant pressure to become a saturated liquid.

Process 3–4 Isentropic Compression: 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 4–1 Constant pressure heat addition: 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.

These process can be explained with the help of the following diagram

Program Code :-

clear all
close all
clc

%Given inputs

T1=300;
P1=20;
P4=P1;
P2=0.07;
P3=P2;

%Calculating entropy and enthalpy at point 1

h1 = XSteam('h_pT',P1,T1);
s1 = XSteam('s_pT',P1,T1);

%At state point 2

s2=s1;

%For an isentropic expansion, ( T2/T1 )= (P2/P1)^(1-(1/gamma))
gamma=1.4;
power=(1-(1/gamma));
T2=T1*((P2/P1)^power);
h2=XSteam('h_pT',P2,T2);

%At state point 3

T3=T2;
h3=XSteam('hL_T',T3);
s3=XSteam('sL_T',T3);

%At state points 4

s4=s3;
T4=XSteam('T_ps',P4,s4);
h4=XSteam('h_pT',P4,T4);
h41=XSteam('hL_p',P4);
s41=XSteam('sL_p',P4);
h42=XSteam('hV_p',P4);
s42=XSteam('sV_p',P4);
T41=XSteam('T_hs',h41,s41);
T42=XSteam('T_hs',h42,s42);

%To calculate the net work output

w_t=h1-h2;
w_p=h4-h3;
w_net=w_t-w_p;

%To calculate back work ratio

bwr=w_p/w_t;

%To calculate Heat supplied & Heat rejected

qs=h1-h4
qr=h2-h3

%To calculate thermal efficiency

thermal_eff=(w_net/qs)*100;

%To calculate specific steam consumption

ssc=3600/w_net;

%To calculate enthalpy and entropy values to get the whole curve

temp=linspace(1,500,600)
for i=1:length(temp)

    sl(i)=XSteam('sL_T',temp(i))
    sv(i)=XSteam('sV_T',temp(i))

    hl(i)=XSteam('hL_T',temp(i))
    hv(i)=XSteam('hV_T',temp(i))
 
end

%Plotting

figure(1);
plot([s1 s2],[T1 T2],[s2 s3],[T2 T3],[s3 s4],[T3 T4],[s4 s41],[T4 T41],[s41 s42],[T41 T42],[s42 s1],[T42 T1],'marker','*','color','r')
hold on
plot(sl,temp)
plot(sv,temp)
xlabel('Entropy (KJ/Kg K)');
ylabel('Temperature (K)');

figure(2)
plot([s1 s2],[h1 h2],[s2 s3],[h2 h3],[s3 s4],[h3 h4],[s4 s1],[h4 h1],'marker','*','Color','g')
hold on
plot(sv,hv);
plot(sl,hl);
xlabel('Entropy (KJ/KgK)')
ylabel('Enthalpy (KJ/K)')

%Displaying the results

disp('Results');
disp('Given inputs');
P1=P1
P2=P2
T1=T1

disp('At state point 1');
n1=sprintf('P1 is %.3f bar',P1);
disp(n1);
n2=sprintf('T1 is %.3f degree celcius',T1);
disp(n2);
n3=sprintf('h1 is %.3f KJ/Kg',h1);
disp(n3);
n4=sprintf('s1 is %.3f KJ/KgK',s1);
disp(n4);

disp('At state point 2');
n5=sprintf('P2 is %.3f bar',P2);
disp(n5);
n6=sprintf('T2 is %.3f degree celcius',T2);
disp(n6);
n7=sprintf('h2 is %.3f KJ/Kg',h2);
disp(n7);
n8=sprintf('s2 is %.3f KJ/KgK',s2);
disp(n8);

disp('At state point 3');
n9=sprintf('P3 is %.3f bar',P3);
disp(n9);
n10=sprintf('T3 is %.3f degree celcius',T3);
disp(n10);
n11=sprintf('h3 is %.3f KJ/Kg',h3);
disp(n11);
n12=sprintf('s3 is %.3f KJ/KgK',s3);
disp(n12);

disp('At state point 4');
n13=sprintf('P3 is %.3f bar',P4);
disp(n13);
n14=sprintf('T4 is %.3f degree celcius',T4);
disp(n14);
n15=sprintf('h4 is %.3f KJ/Kg',h4);
disp(n15);
n16=sprintf('s4 is %.3f KJ/KgK',s4);
disp(n16);

disp('calculated parameters');
n17=sprintf('Work done by the turbine = %.3f',w_t);
disp(n17);
n18=sprintf('Work done by the pump = %.3f',w_p);
disp(n18);
n19=sprintf('Heat supplied = %.3f KJ/K',qs);
disp(n19);
n20=sprintf('Heat rejected = %.3f KJ/K',qr);
disp(n20);
n21=sprintf('Net work done = %.3f KJ/K',w_net);
disp(n21);
n22=sprintf('Thermal efficiency = %.3f %',thermal_eff);
disp(n22);
n23=sprintf('Specific Steam consumption(ssc) = %.3f Kg/KW h',ssc);
disp(n23);
n24=sprintf('Back Work ratio = %.3f',bwr);
disp(n24);

Output :-