Project 2 - Rankine cycle Simulator

RANKINE CYCLE:

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

all four components associated with the ideal rankine cycle are steadycycle are steady devices and thus all the processes that make up the rankine cycle can be analyzed as steady flow process

1.pump:

pump pressurized the liquid water from the condeser prior to going back to the boiler

w_pump=h4-h3

2.boiler:

liquid water enters the boiler and is heated up to super heated state in the boiler

q_in=h1-h4

3.turbine:

steam fro the boiler ,which has elevated temperatures and pressures,expand through the turbine to produce work and then discharged in to condenser

w_turbine=h1-h2

4.condenser;

steam from the turbine is condensed to liquid water in the condenser

q_out=h2-h3

t-s diagram:

1-2 isentopic compression in a pump

2-3 constant pressure heat addition in the bolier

3-4 isentropic expansion in the turbine

4-1 constant pressure heat rejectionin a condenser

REPORT:

aim:

to perform a program on rankine cycle to plot the T-S and H-S graphs and also to calculate thermal efficiency of cycle

governing equations:

turbine_work= h1-h2

pump_work= h4-h3

total work=turbine_work-pump_work

heat_in=h1-h4

heat_out=h2-h3

thermal efficiency=work / heat_in

thermal efficency is ratio of total work to the heat supplied

dryness fraction = ((s2-sf2)/(sg2-sf2))

objective:

the main objective of the program to plot the graphs of h-s and t-s and also to find thermal efficiency of the rankine cycle

body:

the programing language used is matlab

clear all
close all
clc

%process 
fprintf("rankine  cycle simulator \n")
fprintf("1_2 isentropic expansion in  turbine\n")
fprintf("2_3 is constant pressure heat rejection\n")
fprintf("3_4 is isentropic compression in the pump\n")
fprintf("4_1 is comstant volume heat addition\n")

%inputs
p1=input("enter the pressure at inlet of the turbine(in bars): ");
t1=input("enter the temperature at the inlet of the turbine(in degree celcius): ");
p2=input("enter the pressure at the condenser (in bar): ");


% stage1
% xsteam is command to get values of enthalpy,entropy,pressure etc 

h1 = XSteam('h_pT',p1,t1);
s1 = XSteam('s_ph',p1,h1);
disp("  RESULTS\n\n")
fprintf('at state point1 \n')
fprintf('p1 is:%f bars \n',p1)
fprintf('t1 is:%f deg celcius \n',t1)
fprintf('h1 is:%f KJ/Kg \n',h1)
fprintf('s1 is:%f KJ/KgK \n',s1)

%stage 2

s2=s1;
t2=XSteam('T_ps',p2,s2);
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('at state point2 \n')
fprintf('p2 is:%f bars \n',p2)
fprintf('t2 is:%f deg celcius \n',t2)
fprintf('h2 is:%f KJ/Kg \n',h2)
fprintf('s2 is:%f KJ/KgK \n',s2)

%atage3

t3=t2;
p3=p2;
s3=XSteam('sL_p',p3);
h3=XSteam('hL_T',t3);
v3=XSteam('v_ph',p3,h3);
fprintf('at state point3 \n')
fprintf('p3 is:%f bars \n',p3)
fprintf('t3 is:%f deg celcius \n',t3)
fprintf('h3 is:%f KJ/Kg \n',h3)
fprintf('s3 is:%f KJ/KgK \n',s3)

%state4

s4=s3;
v4=v3;
p4=p1;
h4=XSteam('h_ps',p4,s4);
t4=XSteam('T_hs',h4,s4);
fprintf('at state point4 \n')
fprintf('p4 is:%f bars \n',p4)
fprintf('t4 is:%f deg celcius \n',t4)
fprintf('h4 is:%f KJ/Kg \n',h4)
fprintf('s4 is:%f KJ/KgK \n',s4)

%state5

p5=p4;
t5=XSteam('Tsat_p',p5);
h5=XSteam('hL_T',t5);
s5=XSteam('sL_p',p5);
fprintf('at state point5 \n')
fprintf('p5 is:%f bars \n',p5)
fprintf('t5 is:%f deg celcius \n',t5)
fprintf('h5 is:%f KJ/Kg \n',h5)
fprintf('s5 is:%f KJ/KgK \n',s5)

%state6

t6=t5;
p6=XSteam('psat_T',t6);
s6=XSteam('sV_T',t6);
h6=XSteam('hV_T',t6);
fprintf('at state point6 \n')
fprintf('p6 is:%f bars \n',p6)
fprintf('t6 is:%f deg celcius \n',t6)
fprintf('h6 is:%f KJ/Kg \n',h6)
fprintf('s6 is:%f KJ/KgK \n',s6)

% temperature is an array which stores the set of temperature values
% between 1 to 400

temperature=linspace(1,400,500);

% for loop is used to get the set of entropy and enthalpy values at vapour
% and liquid phases for consective temperatures

for i=1:length(temperature)
    sV(i)=XSteam('sV_T',temperature(i));
    sL(i)=XSteam('sL_T',temperature(i));
end

for i=1:length(temperature)
    hV(i)=XSteam('hV_T',temperature(i));
    hL(i)=XSteam('hL_T',temperature(i));
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

%T-S graph plot

figure(1)
hold on
plot(sV,temperature)
plot(sL,temperature)
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")
ylabel("temperature(k)")
xlabel("entropy(kj/kgk)")
axis([0,8,0,450])

% H-s graph plot

figure(2)
hold on
plot(sV,hV)
plot(sL,hL)
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")
ylabel("enthalpy(kj/kg)")
xlabel("entropy(kj/kgk)")
axis([0,8,0,3500])

result:

rankine  cycle simulator 
1_2 isentropic expansion in  turbine
2_3 is constant pressure heat rejection
3_4 is isentropic compression in the pump
4_1 is comstant volume heat addition
enter the pressure at inlet of the turbine(in bars): 30
enter the temperature at the inlet of the turbine(in degree celcius): 400
enter the pressure at the condenser (in bar): 0.05
  RESULTS\n\n
at state point1 
p1 is:30.000000 bars 
t1 is:400.000000 deg celcius 
h1 is:3231.571027 KJ/Kg 
s1 is:6.923260 KJ/KgK 
at state point2 
p2 is:0.050000 bars 
t2 is:32.875490 deg celcius 
h2 is:2110.708472 KJ/Kg 
s2 is:6.923260 KJ/KgK 
at state point3 
p3 is:0.050000 bars 
t3 is:32.875490 deg celcius 
h3 is:137.765119 KJ/Kg 
s3 is:0.476254 KJ/KgK 
at state point4 
p4 is:30.000000 bars 
t4 is:32.963066 deg celcius 
h4 is:140.762226 KJ/Kg 
s4 is:0.476254 KJ/KgK 
at state point5 
p5 is:30.000000 bars 
t5 is:233.858445 deg celcius 
h5 is:1008.371370 KJ/Kg 
s5 is:2.645621 KJ/KgK 
at state point6 
p6 is:30.000000 bars 
t6 is:233.858445 deg celcius 
h6 is:2803.264739 KJ/Kg 
s6 is:6.185788 KJ/KgK 

n =

    0.3617


BWR =

    0.0027


ssc =

    3.2204

graphs:

conclusion:

rankine cycle consists of 2 isentropic and 2 constant pressure processes .rankine cycle is a improved cycle to the carnot cycle ,the main components of the cycle are turbine ,condenser,pump and a boiler which are alligned to a closed cycle

all the values of entropy ,enthalpy and pressure etc can be obtained from XSteam by passing the corresponding functions.its consists of 6 states by taking enthalpy,entropy and temperature we can plot the T-S and H-S diagrams