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Chapter 8: Vapor Power Systems

A view of the GPU International 80 MW natural gas fired plant adjacent to the Syracuse

University campus in Syracuse NY

Photo Courtesy of GPU International

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Components of a Vapor Power Plant

3

Rankine CycleTurbine:

1 2tW h hm

Condenser (1 side):

2 3outQ h hm

Boiler:

1 4inQ h hm

Pump:

4 3pW h hm

Overall Performance:

1 2 4 3

1 4

/ /

/

t p

in

W m W m h h h hh hQ m

4

Rankine Idealizations

Processes 1-2, 3-4: Isentropic

Processes 2-3, 4-1: Isobaric

Saturated liquid at State 3

Reversible Pump Work Equation:

For Incompressible Fluids Only!

3 4 3

int rev

pW v p pm

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Principal Device Analysis:

1 2tW m h h

4 3pW m h h

1 2

1 2t

s

h hh h

4 3

4 3

sp

h hh h

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Principal Device Analysis:

1 4inQ m h h

2 3outQ m h h

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Cycle Performance Parameters

/ /

/

t p

in

W m W m

Q m

/

/

p

t

W mbwr

W m

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Improving Cycle PerformanceOne key is in the pressures:

Each method increases cycle thermal efficiency!

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Improving Cycle Performance

Superheat and Reheat protect the turbine, and increase TH.

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Improving Cycle PerformanceAdding an Open Feedwater Heater (with pump).

6 5

2 5

h hyh h

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Improving Cycle PerformanceAdding a Closed Feedwater Heater.

6 5

2 7

h hyh h