9. Main elements of the collector
} Reflector (mirror)
} Receiver tube
} Structure
} Tracking system
} Connecting elements
} Control system
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GEEN 4830 – ECEN 5007
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15. The receiver tube
Glass pin for evacuation of gases
and steel tubes
Vacuum between glass
Glass – metal welding
Selective coated steel tube
'Getter‘ for vacuum maintenance
Expansion bellow
Glass envelope
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16. Receiver tubes
Schott PTR-70 Solel UVAC-2 and UVAC-3
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17. Heat transfer fluid
} Thermal oils
} Caloria (SEGS I and II, <300ºC)
} Therminol VP-1 (<400 ºC)
} Syltherm (Dow Chemical, >400ºC)
} Water / Steam
} >400 ºC
} DISS Project
} Molten salts
} ENEA facility
} Gases
} PSA Research Facility
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GEEN 4830 – ECEN 5007
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18. Tracking mechanisms
Electrical motor -
gearbox Hydraulic
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22. Solar field configuration (I)
1 SCA 150 m
12 SCE
1 Drive Pylon
10 Middle Pylon
1 End Pylon
1 Shared Pylon (shared with next SCA)
150 m
Shared Pylon
SCE
150 m
Middle Pylon
Drive Pylon
End Pylon
Hot
Oil
Cold
Oil
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GEEN 4830 – ECEN 5007
11/07/11
23. Solar field configuration (2)
Loop of
6 SCA’s
1248 m
SEGS Power Block
80 MW Rankine Cycle Headers
Cross Over
Pipes
1379 m
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GEEN 4830 – ECEN 5007
11/07/11
24. Solar field configuration (3)
C Thermal losses
D Thermal losses
D unbalanced !P
D Higher cost
D Higher consumption
C !P balanced
C Lower consumption
A) Direct return
B) Inverse return
h
h
h
h
C Shorter pipelines
C Better access to collectors
D unbalanced !P
C) Central
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GEEN 4830 – ECEN 5007
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25. Solar Field Alignment
Z Z
Sol
O
S
C
Y
N
O
C
N
Y
Sol
S
X
X
S
S
E
E
a) E-W tracking
b) N-S tracking
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GEEN 4830 – ECEN 5007
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26. Basic parameters
Aperture, A
Parabolic Angulo aceptanciaΦ
Acceptance angle,
de
Reflector Rayorays
Sun solar
Absorber tube
Angulo apertura φ
Aperture angle ,
de
External receiver diameter , D
Diámetro
D
C =.A /π.D
b) Concentration ratio, C
b) Acceptance angle, ϕ
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GEEN 4830 – ECEN 5007
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28. Geometrical losses
Sun
L = concentrator length
φ = incidence angle
Sol
F = focal length
Side view
Absorber tube
Reflecting surface
φ
φ
Shaded
F
area
Plant view
ED
L
Sun
Af = W x ED = W x F x tan(φ)
a) Shading losses
b) Loss of effective collector length
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GEEN 4830 – ECEN 5007
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29. Loss of effective collector length
ED
W
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30. Thermal losses
Absorber tube
Qabs,cond/conv. Qamb,rad
Qamb,conv
Qabs,rad.
Qv,abs.
Qabs,rad + Qabs,cond-conv
U L )abs = [W/m2abs ºC] Glass envelope
πDabs L(Tabs - Tamb )
UL)col = UL)abs / C
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GEEN 4830 – ECEN 5007
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31. Energy balance (solar to thermal)
eff
eff
Qsol = Ac ⋅ I ⋅ cos(ϕ )
Qeff = M ⋅ (hout − hin )
η global = ηopt ,0 º ⋅ K ⋅ηth
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GEEN 4830 – ECEN 5007
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32. Typical operation curve
(clear day, no thermal storage)
Solar Efficiencies Measured at
SEGS VI
100
on July 1997 by KJC Operating
70
Company
% 1200
99 60 Direct Normal
Radiation
- %
%
1000
Direct Normal Radiatiom [W/m²]
Efficiencyi l a b i l i t y
50
98 %
Thermal 800
Solar -
40
% Field
A va
97 Efficiency
600
30
%
[%]
96
20 400
%
95 10
Solar to
% Electric 200
1995 1996 1997 1998 1999
Efficiency
0
(gross)
III IV V VI VII
% 0
05:00 07:00 09:00 11:00 13:00 15:00 17:00 19:00 21:00
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GEEN 4830 – ECEN 5007
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33. Dispatchability of STP Plants
} Integration of RES on the grid:
} Dispatchability is a key factor.
} STP Plants have the potential to be dispatchable by:
} Including a Thermal Storage System (TES)
} Hybridization with fossil or renewable fuels.
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34. Andasol-type plants
(thermal storage and auxiliary boiler)
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GEEN 4830 – ECEN 5007
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35. Dispatchable STP Plant
} Continuous and stable operation is guaranteed by TES
and / or hybridization
50
40
MW
30
20
10
0
0 2 4 6 8 10 12 14 16 18 20 22 24
Hours
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GEEN 4830 – ECEN 5007
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39. Costs
} Difficult to evaluate
} Confidentiality of contracts
} Volatility of prices
} Only 2 – 3 providers of key elements
} O&M experience restricted to US (SEGS Plants)
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GEEN 4830 – ECEN 5007
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