Challenge

Project 2 - Rankine cycle Simulator

AAnagha Udayakumar29 Jun 2022

Rankine Cycle Simulator: Using MATLAB

AIM:

To write a program to calculate the state points of the Rankine Cycle based on user points.Then, plot the corresponding T-s and h-s plots for the given set of inputs with Title and axes labels.

THEORY:

The Rankine cycle is a model used to predict the performance of steam turbine systems.It was also used to study the performance of reciprocating steam engines.The Rankine cycle is an idealised thermodynamic cycle of heat engine that converts heat into mechanical work while undergoing a phase change.It is an idealised cycle in which friction loses in each of the four components are neglected.The heat is supplied externally to a closed loop, which usually uses water as the working fluid.

The Rankine cycle operates in the following steps:

1-2 Isentropic Expansion(expansion in a steam turbine):- Steam from the boiler expands adiabatically from state1 to state2 in a steam turbine to produce work and then is discharged to the condenser (partially condensed).The steam does work on the surroundings (blades of the turbine) and loses an amount of enthalpy equal to the work that leaves the system.The work done by the turbine is given by Wt=H2-H1.Again the entropy remains unchanged.

2-3 Isobaric Heat Rejection (in a heat exchanger):- In this phase,the cycle completes by a constant-pressure processin which heat is rejected from the partially condensed steam.There is heat transfer from the vapour to cooling water flowing ina cooling circuit.The vapor condenses and the temperature of the cooling water increases.The net heat rejected is given by Q required=H2-H3.

3-4 Isentropic Compression (compression in centrifugal pump):- The kiquid condensate is compressed adiabatically from state3 to state4 by centrifugal pumps (usually by condensate pumps and then by feed water pumps).The liquid condensate is pumped from the condenser into high pressure boiler.In this processs, the surroundings do work on the fluid,increasing its enthalpy (h = u+ p*v) and compressing it (increasing its pressure). On the other hand, the entropy remains unchanged. The work required for the compressor is given by Wp = H4 – H3.

4-1 Isobaric Heat Transfer(in a heat exchanger -boiler):- In this phase (between state 4 and state 1) there is a constant-pressure heat transfer to the liquid condensate from an external source since the chamber is open to flow in and out. The net heat added is given by Qadd = H1 – H4.

MAIN PROGRAM:

% Program for Rankine cycle simulator

clear all

close all

clc

% User Inputs

fprintf('%50 n n','RANKINE CYCLE SIMULATOR');

fprintf(' 1-2 is Isentropic Expansion in the Turbine');

fprintf(' 2-3 is Const Pressure heat rejection by the condensor');

fprintf(' 3-4 is Isentropic compression in the pump');

fprintf(' 4-1 is const pressure heat addition by the boiler');

% Inputs

p1=input('Enter the pressure at the turbine inlet(in bar):');

t1=input('Enter the temperature at the turbine inlet (in degree celsius):');

p2=input('Enter the pressure at the condensor(in bar):');

% Inlet of the turbine

s1=XSteam('s_pT',p1,t1);

h1=XSteam('h_pT',p1,t1);

% Inlet of the condensor

s2=s1;

sf2=XSteam('sL_p',p2);

sg2=XSteam('sV_p',p2);

hf2=XSteam('hL_p',p2); % Enthalpy at liquid state

hg2=XSteam('hV_p',p2); % Enthalpy at gaseous state

x2=((s2-sf2)/(sg2-sf2)); % Dryness fraction factor

h2=hf2+(x2*(hg2-hf2));

% Exit of the condensor

p3=p2;

t3=XSteam('Tsat_p',p3);

s3=XSteam('sL_p',p3);

h3=XSteam('hL_p',p3);

v3=XSteam('vL_p',p3);

t2=t3;

% Inlet to the boiler

p4=p1;

s4=s3;

h4=XSteam('h_ps',p4,s4);

cp4=XSteam('Cp_ps',p4,s4);

cv4=XSteam('Cv_ps',p4,s4);

g4=(cp4/cv4);

o=(1-g4)/g4;

% To calculate the f4

% p4^(1-gamma)*t4^gamma=p3^(1-gamma)*t3^gamma

t4=(t3*((p3/p4)^((1-g4)/g4)));

% Calculation

% Work done by the turbine

wt=h1-h2;

% Work done by the pump

wp=h4-h3;

% Net work done

w_net=wt-wp;

% Heat injected in boiler

q_in=h1-h4;

% Heat rejected in condensor

q_out=h2-h3;

% Thermal Efficiency

n=w_net/q_in;

np=n*100;

% Plot for temp vs entropy

figure(1)

% Plot for liquid & vapour saturation curves

t=linspace(0,550,600);

for i=1:length(t)

s_l(i)=XSteam('sL_T',t(i));

end

for i=1:length(t)

s_v(i)=XSteam('sV_T',t(i));

end

plot(s_l,t,'linewidth',2,'color','r')

hold on

plot(s_v,t,'linewidth',2,'color','r')

grid on

% Plot for work done by the turbine

plot([s1,s2],[t1,t2],'linewidth',2,'color','k');

hold on

title('T-s DIAGRAM OR IDEAL RANKINE CYCLE')

xlabel('Entropy(kJ/kgK)')

ylabel('Temperature(k)')

% Plot for heat rejected in condensor

plot([s2,s3],[t2,t3],'linewidth',2,'color','k')

hold on

% Plot for work done by pump

plot([s4,s4],[t3,t4],'linewidth',2,'color','k')

hold on

% Plot for heat injected by boiler

tp=XSteam('Tsat_p',p4);

sp=XSteam('sL_T',tp);

plot([s4,sp],[t4,tp],'linewidth',2,'color','k')

hold on

tq=tp;

sq=XSteam('sV_T',tq);

plot([sp,sq],[tp,tq],'linewidth',2,'color','k')

hold on

plot([sq,s1],[tq,t1],'linewidth',2,'color','k')

hold on

% Indicate state with numbers

text(s1,t1,' 1');

text(s2,t2,' 2');

text(s3,t3,' 3');

text(s4,t4,' 4');

% Plot for enthalpy vs entropy

figure(2)

plot([s1,s2],[h1,h2],'linewidth',2,'color','k')

grid on

title('h-s DIAGRAM')

xlabel('Entropy(kJ/kgK)')

ylabel('Enthalpy(kJ/kgK)')

hold on

plot([s2,s3],[h2,h3],'linewidth',2,'color','k')

hold on

plot([s3,s4],[h3,h4],'linewidth',2,'color','k')

hold on

plot([s4,s1],[h4,h1],'linewidth',2,'color','k')

hold on

% Plot for liquid & vapour saturation curve

t=linspace(0,550,600);

for j = 1:length(t)

h_l(j)=XSteam('hL_T',t(j));

end

for j = 1:length(t)

h_v(j)=XSteam('hV_T',t(j));

end

plot(s_l,h_l,'linewidth',2,'color','r')

hold on

plot(s_v,h_v,'linewidth',2,'color','r')

% Indicate state with numbers

text(s1,h1,'1');

text(s2,h2,'2');

text(s3,h3,'3');

text(s4,h4,'4');

% Results output

fprintf('n %40s nn','RESULT');

frintf('%10s %54s n','AT STATE POINT1','AT STATE POINT2');

fprintf('%s %.2f%s %44s %.2f%s n','P1:',p1,'bar','P2:',p2,'bar');

fprintf('%s %.2f%s %35s %.2f%s n','T1:',t1,'Deg Celcius','T2:',t2,'Deg Celcius');

fprintf('%s %.2f%s %40s %.2f%s n','H1:',h1,'kJ/kg','H2:',h2,'kJ/kg');

fprintf('%s %.2f%s %42s %.2f%s n','S1:',s1,'kJ/kgK','S2:',s2,'kJ/kgK');

fprintf('%58s %.2fn n','X2:',x2);

fprintf('%10s %54s n','AT STATE POINT3','AT STATE POINT4');

fprintf('%s %.2f%s %45s %.2f%s n','P3:',p3,'bar','P4:',p4,'bar');

fprintf('%s %.2f%s %35s %.2f%s n','T3:',t3,'Deg Celcius','T4:',t4,'Deg Celsius' );

fprintf('%s %.2f%s %41s %.2f%s n','H3:',h3,'kJ/kg','H4:',h4,'kJ/kg');

fprintf('%S %.2f%s %42s %.2f%s n n','S3:',s3,'kJ/kgK','S4:',s4,'kJ/kgK');

fprintf('%40s %.2f %s n','Work output by turbine(wt):',wt,'kJ/kg');

fprintf('%40s %.2f %s n','Work input by pump(wp):',wp,'kJ/kg');

fprintf('%40s %.2f %s n','Net work(wnet):',w_net,'kJ/kg');

fprintf('%40S %.2f %s n','Thermodynamic Efficiency(Ntherm):',np,'Percent');

fprintf('%40s %.2f %s n','Heat input in boiler:',q_in,'kJ/kg');

fprintf('%40s %.2f %s n','Heat rejected in condensor:',q_out,'kJ/kg');

fprintf('%40s %.2f %s n','S.S.C.:',p3,'kg/kWh');

Project 2 - Rankine cycle Simulator

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Ship work like this
in your own course.