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Optical and thermal performance of parabolic trough collectors Robert Pitz-Paal, Institute of Solar Research

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Optical and thermal performance of parabolic trough collectors

Robert Pitz-Paal, Institute of Solar Research

Overview

1. Motivation for Improving Performance 2. Qualification of Concentrators 3. Qualification of Receivers 4. Conclusions

www.DLR.de • Chart 2 > Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 3

- Solar field has a high share of the total investment - It is a long-term investment - It is of big extent (corrections are expensive)

- Yearly plant output strongly depends on optical quality of collector field

- Measurements showed that without proper quality assurance 3-10% and in some cases even more of the field performance can be lost

- Quality assurance and final acceptance tests of collector fields are necessary for control of subcontractors and warranty claims

Quality assurance of collector field assembly is indispensable and

makes economic sense

1. Motivation Improved Performance by Proper Implementation of Construction

> Eurotherm No. 98 > Pitz-Paal

What is a parabolic trough?

www.DLR.de • Chart 5

1. Motivation Efficiency Chain, Example: Parabolic Trough

Example ANDASOL: 1% less optical quality means for investors: 0.5 million € less revenues per year 10 million € less revenues per lifetime

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 6

Slide 6 www.dlr.de/enerMENA

• Microscopic surface errors (roughness, deterioration, scratches, …)

microscopic surface errors

missing ray

nideal

2. Qualification of Concentrators Possible Concentrator Errors

• Macroscopic surface deviations (waviness, mirror contour errors, deformations, structural errors, …)

• Positioning of the receiver tube (position of supports, bending of tube, …)

• Tracking errors (tracking, module alignment, collector torsion, …)

• (Sun Shape)

tracking error

mirror contour error

> Eurotherm No. 98 > Pitz-Paal

positioning error of absorber tube

Intercept depends on component quality and alligenement quality

www.DLR.de • Chart 7 > Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 8

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Rec

eive

r

Central Receiver

Parabolic Trough Receiver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot

+ Intercept Simulation

Con

cent

rato

r

Parabolic Trough Coll.

Heliostats

Qualification in Different Phases

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 9

X

Z

camera

dabs

dcam

∆z

∆x

reflector

f

nu

nl

∆αu

α1,u

αu

α1,l

∆αl

αl

2. Qualification of Concentrators Deflectometry

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 10

Slide 10 www.dlr.de/enerMENA

2. Qualification of Concentrators Deflectometry – Image Acquisition

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 12

Focus deviation in mm of reflected ideal rays

2. Qualification of Concentrators Deflectometry – Result

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 13

Local intercept factor in percent with consideration of degraded sunshape

2. Qualification of Concentrators optical

Deflectometry + Intercept Calculation – Result

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 14

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Mat

eria

ls

Rec

eive

r

Central Receiver

Parabolic Trough Receiver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot

+ Intercept Simulation

Con

cent

rato

r

Parabolic Trough Coll.

Heliostats

Qualification in Different Phases

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 15

From photos to coordinates Image acquisition: several photos of measurement object are taken form different angles

Point recognition: clearly recognizable points of object are determined in all photos

Evaluation: calculation of 3D point geometry via initial orientation, intersection and bundle adjustment

Scaling: inclusion of known distances between targets

Result: all object coordinates, camera positions and orientations together with their precisions are known

2. Qualification of Concentrators optical

Photogrammetry: Collector Shape and Deformation

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 16

Object Preparation

2. Qualification of Concentrators optical

Photogrammetry: Collector Shape and Deformation

Results - 3D Coordinates - Coordinate Deviations - Angle Deviations • Shape and Deformation

Studies

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 17

Qualification in Different Phases

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 18

Projector

Camera

Heliostat

Projection screen

Tower

α

α

i

n

r

2. Qualification of Concentrators Deflectometry – Measurement Setup for Heliostats

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 19

Projector

Camera

Heliostat

Projection screen

Tower

α

α

i

n

r

2. Qualification of Concentrators Deflectometry – Measurement Setup for Heliostats

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 20

2. Qualification of Concentrators optical

Deflectometry – Reflected Patterns in Heliostat

horizontal

vertikal

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 21

Mean deviations ⇨ measure for facet tilt

⇨ canting

Measured focal length ⇨ adjustments of focal length Results on heliostat level:

RMS slope deviation = 1.98 mrad Heliostat design focal length = 104.1 m Measured focal length = 116.2 m

Slope deviation in x-direction in mrad Slope deviation in y-direction in mrad

21

1.96 1.32 -0.46 -1.11

0.46 -0.18 -0.16 -1.27

1.32 0.68 -0.17 -1.15

1.13 0.15 0.06 -0.54

1.23 0.01 -0.56 -1.55

0.57 -0.12 -0.04 -1.00

-1.25 -1.72 0.32 1.25

1.33 -0.58 1.00 2.08

-0.29 -0.68 -1.88 1.13

1.02 -0.57 1.18 2.43

0.87 -0.40 -1.34 0.38

0.45 -0.83 -2.45 -1.06

116.8 141.5 145.0 126.7

242.0 97.8 131.5 155.8

152.2 135.3 138.6 137.7

189.0 135.1 142.0 134.8

158.4 143.9 145.5 146.4

143.2 129.0 133.3 143.6

116.8 141.5 145.0 126.7

242.0 97.8 131.5 155.8

152.2 135.3 138.6 137.7

189.0 135.1 142.0 134.8

158.4 143.9 145.5 146.4

143.2 129.0 133.3 143.6

2. Qualification of Concentrators optical

Deflectometry – Results Heliostat CESA-1, PSA

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 22

Mean deviations ⇨ measure for facet tilt

⇨ canting

Measured focal length ⇨ adjustments of focal length Results on heliostat level:

RMS slope deviation = 1.98 mrad Heliostat design focal length = 104.1 m Measured focal length = 116.2 m

Slope deviation in x-direction in mrad Slope deviation in y-direction in mrad

22

1.96 1.32 -0.46 -1.11

0.46 -0.18 -0.16 -1.27

1.32 0.68 -0.17 -1.15

1.13 0.15 0.06 -0.54

1.23 0.01 -0.56 -1.55

0.57 -0.12 -0.04 -1.00

-1.25 -1.72 0.32 1.25

1.33 -0.58 1.00 2.08

-0.29 -0.68 -1.88 1.13

1.02 -0.57 1.18 2.43

0.87 -0.40 -1.34 0.38

0.45 -0.83 -2.45 -1.06

116.8 141.5 145.0 126.7

242.0 97.8 131.5 155.8

152.2 135.3 138.6 137.7

189.0 135.1 142.0 134.8

158.4 143.9 145.5 146.4

143.2 129.0 133.3 143.6

116.8 141.5 145.0 126.7

242.0 97.8 131.5 155.8

152.2 135.3 138.6 137.7

189.0 135.1 142.0 134.8

158.4 143.9 145.5 146.4

143.2 129.0 133.3 143.6

2. Qualification of Concentrators optical

Deflectometry – Results Heliostat CESA-1, PSA

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 23

23

2. Qualification of Concentrators optical

Deflectometry – Raytracing Heliostats CESA-1, PSA

- STRAL, DLR-Raytracing program which can Use Deflectometry Results

- Code Validation by Simulation of a Group of Heliostats with Blocking and Shading

- Comparison with Flux Measurement

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 24

24

2. Qualification of Concentrators optical

Deflectometry – Raytracing Heliostats CESA-1, PSA

Flux Measurement Simulation

Detailed Simulation of Solar Flux Possible by Using Deflecometry Data

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 25

Qualification in Different Phases

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 26

Photogrammetric measurement - 9 orientations with different elevations

(0°,10°,20°,30°,40°,50°,60°,70°,80°,90°)

- 20 photos for each orientation Measurement uncertainty mean over 9 orientations: - σ=0.3 mm - ∆max = 0.6 mm

2. Qualification of Concentrators optical

Photogrammetry: Heliostat Shape and Deformation Object Preparation - 216 targets on 12 facets (18 each)

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 27

Photogrammetry (z-deviation) Measured displacements ∆ between 10° and 90°: - ∆ = 1.1±1.9 mm - ∆max < 5.5 mm

2. Qualification of Concentrators optical

Photogrammetry: Heliostat Shape and Deformation

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 28

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation QDec-M Deflectometry

QFoto Photogrammetry, Laser-Tracker

+ Intercept Simulation

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

Qualification in Different Phases

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 29

29

QDec: Automated System for Horizontal and Vertical Mirror Panels

2. Qualification of Concentrators optical

QDec: Deflectometry Systems for Mirror Panels & Modules

QDec-M: Automated System for 12m-Collector Module

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 30

2. Qualification of Concentrators optical

QFoto: Photogrammetry Setup for Collector Structures

QFoto: Automated System for Collector Structures QFoto-Module Quality Report

Moving Camera

Moving Camera

Structure to be measured

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 31

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation QDec-M Deflectometry

QFoto Photogrammetry, Laser-Tracker

+ Intercept Simulation

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

Qualification in Different Phases

Photogrammetry, QFoto Laser Tracker

QFly Deflectometry, Flux Density Simulation

+ Intercept Simulation

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 32

a) Airborne camera vehicle during a test flight at KONTAS test facility (PSA)

- System successfully validated for single module (against TARMES and Photogrammetrie)

- Measurement uncertainty: local slope deviation.: 0.6 – 1.1 mrad RMS whole module: ca. 0.1 mrad

- Up scaling to complete solar fields d) Slope deviation measured by QFly for KONTAS

collector

[mrad]

b) Automatic creation of flight routes (DISS, PSA)

c) Photogrammetric determination of camera and collector position

2. Qualification of Concentrators optical

Collector Field Shape Measurement: QFly

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 33

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation QDec-M Deflectometry

QFoto Photogrammetry, Laser-Tracker

+ Intercept Simulation

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

Qualification in Different Phases

Photogrammetry, QFoto Laser Tracker

QFly Deflectometry, Flux Density Simulation

+ Intercept Simulation

SAPHIR Deflectometry Flux Density Simulation Flux Density Measurement

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 34

2. Qualification of Concentrators / Receivers optical

Flux Density Measurement

Flux Measurement with Moving Bar Flux Measurement on Receiver Surface

Heliostat Beam Characterization by Flux Measurement - Canting - Tracking Errors

Flux Density by Raytracing-Simulation

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 35

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation

ThermoRec, ElliRec, OptiRec,

KONTAS, Mechanical Prop.

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

Qualification in Different Phases

Production Phase O&M Phase Mass Product Commissioned Plant

QDec-M Deflectometry QFoto Photogrammetry, Laser-Tracker

+ Intercept Simulation

Photogrammetry, QFoto Laser Tracker

QFly Deflectometry, Flux Density Simulation

+ Intercept Simulation

SAPHIR Deflectometry Flux Density Simulation Flux Density Measurement

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 36

Features: - Internal Electric Heating - End Heaters for Homogeneous

Temperature Profile - Temperature Measurement of

Absorber inside Glass Envelope End Caps Surface

- Calculation of Axial End Losses (~3%) and Correction of Power

Measurements: - Standardized Component Qualification - Laboratory Measurement of Thermal Losses - Principle: Electrical Heating = Heat Loss

3. Qualification of Receivers thermal

Receiver Qualification - ThermoRec

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 37

Measurements: - Standardized Component Qualification for

Comparative Measurements - Laboratory Measurement of Optical

Performance

3. Qualification of Receivers optical

Receiver Qualification - ElliRec

Measurement Principle: - Heating by Metal-Halide Lamps and Elliptical

Concentrator - No Thermal Losses, as Ambient Temperature - Measuring Flow Rate of Water - Measuring Temperature Increase (ΔT ~ 7 K) Absorbed Power

- Exact Lamp Power unknown, but constant Comparative Measurements to one Virtual 70-mm Master Receiver

> Eurotherm No. 98 > Pitz-Paal

OptiRec: 2nd generation test bench for Optical Receiver

Method: - similar to ElliRec Goals: - improve long term stability of optics and

reproducibility - facilitate replication standardization - improved handling - shorter measurement time - smaller dimensions Status: - operational since early 2013 - high reproducibility of the measurement

of ~ ± 0.2 (1σ) shown - compatibility with ElliRec shown

> Eurotherm No. 98 > Pitz-Paal www.DLR.de • Chart 38

www.DLR.de • Chart 39

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation

ThermoRec, ElliRec, OptiRec,

KONTAS, Mechanical Prop.

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

Qualification in Different Phases

QDec-M Deflectometry QFoto Photogrammetry, Laser-Tracker

+ Intercept Simulation

Photogrammetry, QFoto Laser Tracker

QFly Deflectometry, Flux Density Simulation

+ Intercept Simulation

SAPHIR Deflectometry Flux Density Simulation Flux Density Measurement

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 40

Features: - Rotative test-platform - Max. Collector Length: 20 m - Active Temperature Control - Heat Transfer Fluid: Syltherm 800 - Operation Temperature: ≤ 400 °C - Mass Flow: <6 kg/s - High Precision Meteo Station - Redundant Calibrated PT-100

Measurements: - Standardized Component Qualification - On-Sun Measurement of Optical and Thermal Efficiency - Component Performance

3. Qualification of Concentrators & Receivers optical & thermal

KONTAS Test Bench at PSA Temperature control unit

23 m

Eurotrough 12m

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 41

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation

ThermoRec, ElliRec, OptiRec,

KONTAS, Mechanical Prop.

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

Qualification in Different Phases

QDec-M Deflectometry QFoto Photogrammetry Laser-Tracker

+ Intercept Simulation

Photogrammetry, QFoto Laser Tracker

QFly Deflectometry, Flux Density Simulation

+ Intercept Simulation

SAPHIR Deflectometry Flux Density Simulation Flux Density Measurement

Receiver Efficiency Meas. Several manufacturing specific quality

control measures

Several manufacturing specific quality

control measures

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 42

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation

ThermoRec, ElliRec, OptiRec,

KONTAS, Mechanical Prop.

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

Qualification in Different Phases

QDec-M Deflectometry QFoto Photogrammetry Laser-Tracker

+ Intercept Simulation

Photogrammetry, QFoto Laser Tracker

QFly Deflectometry, Flux Density Simulation

+ Intercept Simulation

SAPHIR Deflectometry Flux Density Simulation Flux Density Measurement

Receiver Efficiency Meas. Several manufacturing specific quality

control measures

Several manufacturing specific quality

control measures

Receiver Efficiency Meas.

QFly-IR Screening Measure. PARESO HCE Field Meas. Mobile Test Units, Bypass

> Eurotherm No. 98 > Pitz-Paal

www.DLR.de • Chart 43

Phases Objects

R&D Phase Production Phase O&M Phase Prototypes Mass Product Commissioned Plant

Con

cent

rato

r R

ecei

ver

TARMES Deflectometry Photogrammetry Inclinometer, V-Shot Parabolic Trough Coll.

Central Receiver

Parabolic Trough Receiver

+ Intercept Simulation

ThermoRec, ElliRec, OptiRec,

KONTAS, Mechanical Prop.

SAPHIR Deflectometry, Photogrammetry, Inclinometer Heliostats

+ Intercept Simulation

Qualification in Different Phases

QDec-M Deflectometry QFoto Photogrammetry Laser-Tracker

+ Intercept Simulation

Photogrammetry, QFoto Laser Tracker

QFly Deflectometry, Flux Density Simulation

+ Intercept Simulation

SAPHIR Deflectometry Flux Density Simulation Flux Density Measurement

Receiver Efficiency Meas. Several manufacturing specific quality

control measures

Several manufacturing specific quality

control measures

Receiver Efficiency Meas.

QFly-IR Screening Measure. PARESO HCE Field Meas. Mobile Test Units, Bypass

> Eurotherm No. 98 > Pitz-Paal

Conclusion

- Optical quality of components and their alignment are critical for the commercial success of CSP plants

- High quality measurement systems on component and subsystem level exist and are partly transferred to industry

- Measurement systems together with Ray tracing and Finite Element Tools improve the understanding of the system and allow for optimization

- We feed our experience on optical and thermal performance measurements into standardization initiatives

- In situ performance and degradation measurements is one important subject for further development

www.DLR.de • Chart 44 > Eurotherm No. 98 > Pitz-Paal

Final Quality Inspection Procedure …