Project 2 - Rankine cycle Simulator
Aim: To create a Rankine cycle simulator using Matlab and plot the corresponding T-S and H-S diagram for the given sets of inputs.
Objective: To create a Rankine cycle simulator and calculate all the state points in it. And plot of T-S and H-S diagram for the inputs given in the question.
Rankine Cycle:
Rankine is an ideal thermodynamic cycle, here by moving a fluid between a heat source and heat sink a mechanical work is extracted, such as steam turbines or reciprocating steam engines. Heat is supplied through a boiler and there high pressure gas forms and it will run the turbine. After running the turbine the gas goes to the condensor part where it rejects all the heat and condenses. Then this fluid is again taken to the boiler through a pump. In rankine cycle there are four processes, they are:
- 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.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.
- 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.
Matlab code:
clear all
close all
clc
%displaying rankine cycle simulator and its processes
disp(" Rankine Cycle Simulator")
fprintf('1-2 is the isentropic expansion process')
fprintf('\n2-3 is the constant pressure heat rejection process')
fprintf('\n3-4 is the isentropic compression process')
fprintf('\n4-1 is the constant pressure heat addition process')
% State variables At state point 1
p1=30;
t1=400;
h1=Xsteam('h_pT',30,400);
s1=Xsteam('s_ph',30,h1);
fprintf('\n\n Results')
fprintf('\n\n At state point 1')
fprintf('\n P1 is:%f bar',p1)
fprintf('\n T1 is:%f deg celcius',t1)
fprintf('\n H1 is:%f KJ/Kg',h1)
fprintf('\n S1 is:%f KJ/KgK',s1)
% State variables At state point 2
p2=0.05;
s2=s1;
t2=Xsteam('T_ps',0.05,6.1858);
sf2=Xsteam('sL_p',p2);
sg2=Xsteam('sV_p',p2);
hf2=Xsteam('hL_p',p2);
hg2=Xsteam('hV_p',p2);
x=((s2-sf2)/(sg2-sf2));
h2=hf2+(x*(hg2-hf2));
v2=Xsteam('v_ph',p2,h2);
fprintf('\n\n At state point 2')
fprintf('\n P2 is:%f bar',p2)
fprintf('\n T2 is:%f deg celcius',t2)
fprintf('\n H2 is:%f KJ/Kg',h2)
fprintf('\n S2 is:%f KJ/KgK',s2)
% State variables At state point 3
p3=p2;
t3=t2;
h3=Xsteam('hL_T',32.875);
s3=Xsteam('sL_p',p3);
v3=Xsteam('v_ph',p3,h3);
fprintf('\n\n At state point 3')
fprintf('\n P3 is:%f bar',p3)
fprintf('\n T3 is:%f deg celcius',t3)
fprintf('\n H3 is:%f KJ/Kg',h3)
fprintf('\n S3 is:%f KJ/KgK',s3)
% State variables At state point 4
p4=p1;
s4=s3;
v4=v3;
h4=Xsteam('h_ps',p4,s4);
t4=Xsteam('T_hs',h4,s4);
fprintf('\n\n At state point 4')
fprintf('\n P4 is:%f bar',p4)
fprintf('\n T4 is:%f deg celcius',t4)
fprintf('\n H4 is:%f KJ/Kg',h4)
fprintf('\n S4 is:%f KJ/KgK',s4)
% State variables At state point 5
p5=p4;
t5=Xsteam('Tsat_p',p5);
h5=Xsteam('hL_T',t5);
s5=Xsteam('sL_p',p5);
fprintf('\n\n At state point 5')
fprintf('\n p5 is:%f bar',p5)
fprintf('\n T5 is:%f deg celcius',t5)
fprintf('\n H5 is:%f KJ/Kg',h5)
fprintf('\n S5 is:%f KJ/KgK',s5)
% State variables At state point 6
t6=t5;
p6=Xsteam('psat_T',t5);
h6=Xsteam('hV_T',t6);
s6=Xsteam('sV_T',t6);
fprintf('\n\n At state point 6')
fprintf('\n P6 is:%f bar',p6)
fprintf('\n T6 is:%f deg celcius',t6)
fprintf('\n H6 is:%f KJ/Kg',h6)
fprintf('\n S6 is:%f KJ/KgK',s6)
%loop to find variables on saturation lines
t=linspace(0,400,1000);
for i=1:length(t)
s_line1(i)=Xsteam('sL_T',t(i));
end
for j=1:length(t)
s_line2(j)=Xsteam('sV_T',t(j));
end
for i=1:length(t)
h_line1(i)=Xsteam('hL_T',t(i));
end
for j=1:length(t)
h_line2(j)=Xsteam('hV_T',t(j));
end
%net work output calculation
w_turbine=h1-h2;
w_pump=h4-h3;
work=w_turbine-w_pump;
q_in=h1-h4;
q_out=h2-h3;
%thermal efficiency
n=work/q_in;
%back work ratio
BWR=w_pump/w_turbine;
%specific steam consumption
ssc=3600/work;
%plottin T-s graph
figure(1)
hold on
plot([s_line1 s_line2],[t t])
plot([s1 s2 s3 s4 s5 s6 s1],[t1 t2 t3 t4 t5 t6 t1])
text(s1,t1,'1')
text(s2,t2,'2')
text(s3,t3,'3')
text(s4,t4,'4')
text(s5,t5,'5')
text(s6,t6,'6')
title('Rankine Cycle T-S diagram')
xlabel('Entropy(KJ/KgK)')
ylabel('Temperature(K)')
axis([0,8,0,450])
%plotting h-s graph
figure(2)
hold on
plot([s_line1 s_line2],[h_line1 h_line2])
plot([s1 s2 s3 s4 s5 s6 s1],[h1 h2 h3 h4 h5 h6 h1])
text(s1,h1,'1')
text(s2,h2,'2')
text(s3,h3,'3')
text(s4,h4,'4')
text(s5,h5,'5')
text(s6,h6,'6')
title('Rankine Cycle H-S diagram')
xlabel('Entropy(KJ/KgK)')
ylabel('Enthalpy(KJ/Kg)')
axis([0,8,0,3500])
Procedure:
- First of all use clear all,close all and clc for clearing workspace data, clearing plots and figures and to clear data in the command window.
- Using disp command we will "Rankine cycle simulator" and then followed by all the proccess occuring in a rankine cycle which is dispalyed using fprintf command.
- Now we find the state variables at each points. The turbine inlet pressure,p1 is taken as 30 bar and inlet temperature is taken as 400K and turbine outlet temperature is taken as 0.05bar.
- We will put Xsteam.m file in the same path and call the xsteam function to find respective state point values.
- After finding each state point variables we will use fprintf command to diplay the results in the command window.
- Now we use for loop to find the values of enthalpy and entropy at saturated temperature and store them into variables.
- Using the formulas we will find the net work output and back work ratio.
- At last we will plot the graph of T-S and H-S diagram from all the values that we obtained from the above procedure.
- And also will plot the saturation line using the values we found by for loop.
Results:
Plots of T-S and H-S diagram
