Regenerative Cycle:
Regenerative cycle is shown is the figure below.
To decrease the irreversibility of the process regenerative cycle is introduced. Less irreversibility mean greater efficiency.
Steam from the boiler enters the turbine and there is partial expansion of the turbine from pressure P1 to a pressure P2. At the state 2, some of the steam is extracted and fed to feed-water heater 1 for the purpose of heating water coming from the condenser. Further expansion of the steam takes place, and it reaches to a pressure P3. Some amount of water is also extracted for Feed water heater 2.
Complete expansion of the steam takes place up to pressure P4, i.e the condenser pressure. The purpose of heating water before it enters the boiler is to increase efficiency by decreasing irreversibility, and the phenomenon is called Regeneration.
Various processes are as explained below.
1-2: Isentropic Expansion of 1Kg of steam in turbine up to pressure P2.
2-3: (1-m1) Kg of steam expands in the turbine from pressure P2 to P3.
3-4: (1-m1 -m2) Kg of steam expands from P3 to condenser pressure P4 in the turbine.
4-5: Constant temperature and pressure condensation in the condenser.
5-6: Isentropic pressure rise in the Pump1.
6-7: Constant pressure heating in feed water heater 2.
7-8: Isentropic pressure rise in pump 2.
8-9: Constant pressure heating of feed water 1.
9-10: Isentropic pressure rise in the main pump.
10-1: Constant pressure heating in the Boiler.
Heat supplied in the Boiler = Q1 = h1 - h10
Work output of the turbine = Wt = (h1 -h2) +(1- m1)(h2 - h3) + (1-m1-m2)(h3 -h4)
Work input of the pump = Wp= (h10 - h9) +(1-m1)(h8 - h7)+(1-m1-m2)(h6 -h5)
Heat to condenser = Q2= (1- m1-m2)(h4-h5)
Thermal efficiency = (Wt- Wp)/Q1
We can see that heat lost in the condenser is reduced by an amount = (m1+m2)(h4-h5)
By
www.makarticles.com
Regenerative cycle is shown is the figure below.
Steam from the boiler enters the turbine and there is partial expansion of the turbine from pressure P1 to a pressure P2. At the state 2, some of the steam is extracted and fed to feed-water heater 1 for the purpose of heating water coming from the condenser. Further expansion of the steam takes place, and it reaches to a pressure P3. Some amount of water is also extracted for Feed water heater 2.
Complete expansion of the steam takes place up to pressure P4, i.e the condenser pressure. The purpose of heating water before it enters the boiler is to increase efficiency by decreasing irreversibility, and the phenomenon is called Regeneration.
Various processes are as explained below.
1-2: Isentropic Expansion of 1Kg of steam in turbine up to pressure P2.
2-3: (1-m1) Kg of steam expands in the turbine from pressure P2 to P3.
3-4: (1-m1 -m2) Kg of steam expands from P3 to condenser pressure P4 in the turbine.
4-5: Constant temperature and pressure condensation in the condenser.
5-6: Isentropic pressure rise in the Pump1.
6-7: Constant pressure heating in feed water heater 2.
7-8: Isentropic pressure rise in pump 2.
8-9: Constant pressure heating of feed water 1.
9-10: Isentropic pressure rise in the main pump.
10-1: Constant pressure heating in the Boiler.
Heat supplied in the Boiler = Q1 = h1 - h10
Work output of the turbine = Wt = (h1 -h2) +(1- m1)(h2 - h3) + (1-m1-m2)(h3 -h4)
Work input of the pump = Wp= (h10 - h9) +(1-m1)(h8 - h7)+(1-m1-m2)(h6 -h5)
Heat to condenser = Q2= (1- m1-m2)(h4-h5)
Thermal efficiency = (Wt- Wp)/Q1
We can see that heat lost in the condenser is reduced by an amount = (m1+m2)(h4-h5)
By
www.makarticles.com
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