Lecture 10: Design process for Solar Fields with Parabolic ...
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Lecturer: Eduardo Zarza Moya Plataforma Solar de Almería – CIEMAT (e-mail: [email protected]) First Summer School Part A: Line-focus Solar Thermal Technologies September 20-24, 2021 Lecture 10: Design process for Solar Fields with Parabolic Trough Collectors
Transcript of Lecture 10: Design process for Solar Fields with Parabolic ...
Lecturer: Eduardo Zarza MoyaPlataforma Solar de Almería – CIEMAT(e-mail: [email protected])
First Summer SchoolPart A: Line-focus Solar Thermal Technologies
September 20-24, 2021
Lecture 10:Design process for Solar Fields with Parabolic Trough Collectors
Slide 22 / 26“Design process for PTC solar fields”
Design Process for Solar Fields with PTCs
Content
The “Design Point” parameters
Number of collectors in series within each row
Number of parallel rows
Electrical power of the pumping equipment
Slide 33 / 26“Design process for PTC solar fields”
Content
The “Design Point” parameters
Number of collectors in series within each row
Number of parallel rows
Electrical power of the pumping equipment
Design Process for Solar Fields with PTCs
Slide 44 / 26“Design process for PTC solar fields”
What is the “Design Point” for a solar field ?The “Design Point” is the set of parameters under which the solar field willdeliver its nominal power. For a set of parameters different from the “DesignPoint”, the solar field will provide less or higher power than its nominal one
Important RemarkSince the energy source of a solar field is the solar radiation, theoutput thermal power delivered by the solar field will change as thesolar radiation changes along the day during the sunlight hours.However, the term “Nominal Power” is used as a reference for thethermal power delivered by the solar field
Design Process for Solar Fields with PTCs
Slide 55 / 26“Design process for PTC solar fields”
Typical solar field with PTCs
“M” parallel rows with “N” collectors in series within each row
IndustrialProcess
The main objective of the design of a solar field with PTCs is the determination of a) the number of collectors that must be connected in series within each row, and b) the number of parallel rows needed
Design Process for Solar Fields with PTCs
Slide 66 / 26“Design process for PTC solar fields”
Design procedure (I)
Definition of the Design Point parameters:• Orientation of the collectors
Design Process for Solar Fields with PTCs
Slide 77 / 26“Design process for PTC solar fields”
Performance in a clear day in June Performance in a clear day in December
Influence of the collector orientation on the seasonal performance
(Simulation of a ET-100 collector installed in Southern Spain)
0 2 4 6 8 10 12 14 16 18 20 22 240
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Orientación Norte-Sur Orientación Este-Oeste
P colec
tor->
fluido
(kW
)
Hora Solar
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North-South orientation East-West orientation
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Orientación Norte-Sur Orientación Este-Oeste
P cole
ctor
->flu
ido (
kW)
Hora Solar
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North-South orientation East-West orientation
Design Process for Solar Fields with PTCs
Slide 88 / 26“Design process for PTC solar fields”
• Location (geographic Latitude and Longitude)• Day and Hour for the Design Point
Design procedure (I)
Definition of the Design Point parameters :• Orientation of the collectors
Design Process for Solar Fields with PTCs
Slide 99 / 26“Design process for PTC solar fields”
0 2 4 6 8 10 12 14 16 18 20 22 240
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P Col
lect
or →
fluid
(kW
)
Solar Time
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JanuaryFebruaryMarchAprilMayJune
(Simulation of a ET-100 collector installed at the PSA)
Daily net thermal power delivered by a Parabolic Trough Collector(oriented East-West)
Design Process for Solar Fields with PTCs
Slide 1010 / 26“Design process for PTC solar fields”
(Simulation of a ET-100 collector installed at the PSA)
Daily net thermal power delivered by a Parabolic Trough Collector(oriented North-South)
4 6 8 10 12 14 16 18 200
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350Po
tenc
ia T
érm
ica
Útil
Hora Solar
Enero Febrero Marzo Abril Mayo Junio
JanuaryFebruaryMarchAprilMay June
P Col
lect
or→
fluid
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th
Solar Time
Design Process for Solar Fields with PTCs
Slide 1111 / 26“Design process for PTC solar fields”
Direct Solar irradiance in a clear day of June and December (at PSA site)
Selection of the Hour for the Design Point
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Junio Diciembre
Irrad
iancia
Sola
r Dire
cta (W
/m2 )
Hora Solar
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Dire
ct S
olar
Irra
dian
ce, (
W/m
2 )
Solar Time
June December
Design Process for Solar Fields with PTCs
Slide 1212 / 26“Design process for PTC solar fields”
• Incidence Angle• Direct solar irradiance and ambient temperature
• Location (geographic Latitude and Longitude)• Day and Hour for the Design Point
Design procedure (I)
Definition of the Design Point parameters :• Orientation of the collectors
Design Process for Solar Fields with PTCs
Slide 1313 / 26“Design process for PTC solar fields”
Assessment of the Direct Solar Radiation using satellite pictures
Design Process for Solar Fields with PTCs
Slide 1414 / 26“Design process for PTC solar fields”
• Solar Field Inlet and Outlet Temperatures• Solar field nominal thermal power (or net thermal energy)
Selection of the solar collector model Selection of the working fluid
• Incidence Angle• Direct solar irradiance and ambient temperature
• Location (geographic Latitude and Longitude)• Day and Hour for the Design Point
Design procedure (I)
Definition of the Design Point parameters :• Orientation of the collectors
Design Process for Solar Fields with PTCs
Slide 1515 / 26“Design process for PTC solar fields”
Content
The “Design Point” parameters
Number of collectors in series within each row
Number of parallel rows
Electrical power of the pumping equipment
Design Process for Solar Fields with PTCs
Slide 1616 / 26“Design process for PTC solar fields”
Number of collectors in each row, N
cTT
N∆∆
=N = number of collectors to be connected in series in each row∆T = Fluid temperature increase in the solar field (To – Ti)∆Tc = Fluid temperature increase in a collector
• Calculation of ∆Tc using the energy balance:( )inoutmfluidcollectorQ hhqP −⋅=→, ∫
o
i
T
Tp dTC ·= qm ·
being Ti the mean fluid temperature in the solar field
• Calculation of the mass flow to assure a Re ≥ 2x105
(Re = ρ ·v ·d /µ)• If GbxCos(ϕ)≥ 800 → Re = 4x105. • If 500 ≤ GbxCos(ϕ) ≤ 800 → Re = 3x105. • If GbxCos(ϕ) ≤ 500 → Re = 2x105.
Design Procedure (II)
• Calculation of “N” using the equation: cTTN ∆∆= /
• Calculation of the nominal power of a collectorº0,optηPQ, collector→fluid = · · K(θ) · Fe − PQ,collector→ambient=Ac· Gb · Cos (θ)·
Design Process for Solar Fields with PTCs
Slide 1717 / 26“Design process for PTC solar fields”
Calculation of the number of parallel rows
In this case the number of parallel rows is given by the quotient of the solar field nominal power in the Design Point and the nominal power of a single row of collectors in the Design Point.
Option a) System without thermal storage
Option b) System with thermal storageIn this case, the number of parallel rows is given by the quotient of the total thermal energy demanded by the Process in de design day and the thermal energy delivered by a single row in the design day from sunrise to sunset.
Design Procedure (III)
Design Process for Solar Fields with PTCs
Slide 1818 / 26“Design process for PTC solar fields”
Thermal Storage System
a) a constant thermal power has to be delivered to the process
A thermal storage system is needed when:
b) thermal energy has to be delivered when sunlight is not available
Solar field output powerPower to the process
Energy surplus
Energy deficit
Hours
Ther
mal
Pow
er,
(MW
t)
Energy deficit
Energy surplus
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Solar field output powerPower to the process
Ther
mal
Pow
er,
(MW
t)
Hours
Design Process for Solar Fields with PTCs
Slide 1919 / 26“Design process for PTC solar fields”
Calculation of the thermal energy on the basis of the thermal powerPower
Ther
mal
pow
er,
(MW
t)
Hours0 2 4 6 8 10 12 14 16 18 20 22 24
0,0
0,2
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1,0
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· · ··
· ·· ·
· ··
Energía
Design Process for Solar Fields with PTCs
Slide 2020 / 26“Design process for PTC solar fields”
Content
The “Design Point” parameters
Number of collectors in series within each row
Number of parallel rows
Electrical power of the pumping equipment
Design Process for Solar Fields with PTCs
Slide 2121 / 26“Design process for PTC solar fields”
Electrical pumping power, Pe, for the solar field
Pe in Watts, WV1 , V in m3/s∆P1 ,∆P in Pascals, Pa (1 bar = 105 Pa)
Pe = Pb/ηe = Pf / ηb · ηe = VTotal·∆P/ηe .ηb= N. V1row . ∆P /ηe .ηb
Pi
Po ∆P = Po – Pi
ηeηbPe
Pf
Pb∼
Design of the Feed Pump for a Solar Field with PTC
Pf (W)=∆P(Pa) ·Flowrate (m3/s)
Slide 2222 / 26“Design process for PTC solar fields”
.
.
Row n
Row 1
Row n/2
Industrial Process Steam Generator
o i
∆P = Po – Pi
En/2
En
E1
Sn
Sn/2
1
2
CollectorCollector Collector
Collrctor
Calculation of the pressure drop ∆P in a multi-row solar field
Design of the Feed Pump for a Solar Field with PTC
Slide 2323 / 26“Design process for PTC solar fields”
.
.
∆P = Po-Pi = (Po-PEn) + (PEn-PSn) +(PSn-P1) + (P1-P2) + (P2- Pi)
o i
En/2
Sn/2
1
2
En
SnRow n
Row 1
Row n/2
Industrial Process Steam Generator
Calculation of the pressure drop ∆P in a multi-row solar field
All pressure values in Pascals, Pa(1 bar = 105 Pa)
CollectorCollector Collector
Collrctor
Design of the Feed Pump for a Solar Field with PTC
Lecturer: Eduardo Zarza MoyaPlataforma Solar de Almería – CIEMAT(e-mail: [email protected])
First Summer SchoolPart A: Line-focus Solar Thermal Technologies
September 20-24, 2021
Lecture 10:Design process for Solar Fields with Parabolic Trough Collectors
- Thank you very much for your attention- Questions?
