Siemens SGT6-5000F(4) 150 MW power Gas Turbine
Gas turbine based power generation
hfCH4= 5.543×107 J / kg
Cycle Analysis
Across the burner.
τ f =hfCpT0
= 5.543×107
1005 × 298.15= 185
Power balance.
Divide by maCpT0
Work output coefficient.
= 1
Ideal Cycle.
τ cτ t = 1
The system is designed to take as much work as possible out of the turbine. The exit Mach number is very low and the exit pressure is very close to the ambient pressure.
Pt5 = Pte ≅ P0
π t = τ tγγ −1
For the ideal cycle the maximum work output coefficient occurs when
τ t =1τλ
and
Ideal Gas Turbine Power Generator.
f =τλ − τλ
τ f −τλ
Example, let
Gas Turbines for Power Generation
Capstone Turbine Corp - microturbine
Example from a previous midterm
ηoverall max =
τ λ 1− 1
ηpcτ λ( )ηpc
1+ηpc
⎛
⎝
⎜⎜⎜
⎞
⎠
⎟⎟⎟− ηpcτ λ( )
11+ηpc −1
⎛⎝⎜
⎞⎠⎟
τ λ −τ x ηpcτ λ( )1
1+ηpc
ηoverall max ideal =
τ λ 1− 1
τ λ( )12
⎛
⎝⎜⎜
⎞
⎠⎟⎟− τ λ( )
12 −1⎛
⎝⎜⎞⎠⎟
τ λ − τ λ( )12
=4 1− 1
2⎛⎝⎜
⎞⎠⎟ − 2 −1( )
4 − 2= 1
2
In the ideal case with τ x = 1
In the real case with τ x = 1
ηoverall max real =
τ λ 1− 1
ηpcτ λ( )ηpc
1+ηpc
⎛
⎝
⎜⎜⎜
⎞
⎠
⎟⎟⎟− ηpcτ λ( )
11+ηpc −1
⎛⎝⎜
⎞⎠⎟
τ λ −τ x ηpcτ λ( )1
1+ηpc
=
4 1− 1
3( )37
⎛
⎝⎜⎜
⎞
⎠⎟⎟− 3( )
47 −1⎛
⎝⎜⎞⎠⎟
4 − 3( )47
= 0.29561
In the real case the efficiency is only about 30% compared to 50% for the ideal case
τ x =1ηpc
= 43
In the real case with
The recuperator improves the efficiency of the real engine by 12%