peter heller department qualification german aerospace center...

R&D on predicting component and material failure

Peter Heller

Department Qualification

German Aerospace Center DLR

CSP Today Sevilla 2014

www.DLR.de • Chart 1 > Institute of Solar Research > Department Qualification> 2014 CSP Today Seville, 13.11.2014

R&D on predicting component and material failure

Motivation

-Material and component failures are leading to

-Higher investment cost (financing, bancability, guarantees)

-Higher maintenance cost (personnel, spare parts)

-Less revenues from operation (down-times, performance loss)

-Performance test in laboratory

-Durability and lifetime prediction

Needs


Components of major interest

- Mirrors

- Receivers

- Ball Joints


Methodology Mirrors

Commercial mirrors

Field operation

„accelerated“

degradation

mechanism

„natural“

degradation

mechanism

Guideline for durability testing of reflectors

Accelerated

aging testing

Indoor storage

-www.DLR.de • Chart 4

> Institute of Solar Research > Department Qualification> 2014 CSP Today Seville, 13.11.2014

Ageing of aluminium mirrors

• Definition accelerated test methods and deduction of correlations to outdoor weathering sites

Gerichtete

ReflexionsverlusteΔρS + ΔρK

Gerichtete

ReflexionsverlusteΔρS + ΔρK

Direct reflectance exposed samples without protection layer in Almeria

Adaptation of production process by manufacturer for increased life expectancy

• Modeling of reflectance prediction by measurement of corrosion induced reflectance loss

Correlation salt spray test Golden, USA

Provision of methods for estimation of life expectancy of new materials

6 months outdoor weathering

560 h Salt spray test ISO 9227

Outdoor weathering time [months]

Sa

lt s

pra

y t

estin

g [h

ou

rs]


Ageing of Reflectors

• Reflector Laboratory (OPAC) with CIEMAT

• Independent test laboratory for industry services

• Outdoor weathering in Spain / North Africa

• Optical Characterization and microscopy

• Standardized aging tests

ISO 9227: Salt spray test

IEC 62108: Damp heat test

ISO 11507: UV light and moisture exposure

DIN 50018: Kesternich Test

ISO 61215: Temperature Cycle Test

ISO 6270-2CH: Humidity test

IEC 62108: Humidity frost test

MIL-STD 810G: Sand abrasion

ISO 11998: Wet scrub resistance

ISO 92114: Abrasion optical coatings

Outdoor weathering

Salt spray test ISO 9227

UV light and moisture ISO11507 [Atlas]


Tested mirror samples

3 protection lacquers 2 protection lacquers 2 protection lacquers,

without copper layer

Sample code: A1, A2, A3, C1 Sample code: B1 Sample code: C2

Type A: Commercial products (outdoor proven)

Type B: Prototype product (no outdoor data available)

Type C: Commercial product (degradation observed in Tabernas, Spain / Newcastle, Australia)

-www.DLR.de • Chart 7 > Institute of Solar Research > Department Qualification> 2014 CSP Today Seville, 13.11.2014

Outdoor degradation of sample C2 in

Newcastle, Australia

Pitting corrosion up to 29 mm in diameter


Outdoor degradation of sample C2 in Newcastle, Australia

Intact layer structure

Glass

Prime Coat

Top Coat

Silver layer

Glass

Cross section of local corrosion spot



Chloride and Sulfur

and Silicon found in

delamination gap


Sulfur and Iron found in pinhole

Area 1

Area 2


Pinhole in paint

2

1

Fe

S


• Area 1 has an increased amount of NaCl

at interface

• NaCl still observed outside corrosion front

Area 1

NaCl

Area 2

Low NaCl

Corrosion

Edge

Undamaged

Ag Reflector


1 2 Cl

Cl


Glass 4 mm

Silver

Prime Coat

Top coat

Delamination in Glass – silver interface


pinhole

Silver

chloride

Silicon, Chloride

and Sulfur

containing filling

material


Methodology

Commercial mirror samples

Field operation

„accelerated“

degradation

mechanism

„natural“

degradation

mechanism

Guideline for durability testing of reflectors

Accelerated

aging testing

Indoor storage


-Chart 15

Accelerated aging

No differences

visible after 480 h


• Heating with heating rods

• Overheating test: performed with at 478 °C for

1000 h

• Thermal cycling test: 200°C to 478°C for

100 cycles

→ Necessity to limit heat up speed at T > 400 °C

k: reactions per time

A: constant (prefactor)

EA: activation energy

R: universal gas constant

T: temperature in K

Overheating And Thermal Cycling Test Bench

Arrhenius equation

𝑘 = 𝐴 ∙ 𝑒−𝐸𝐴𝑅∙𝑇


Bellow Fatigue Test Bench

• heating with internal heating rods

• absorber 200 °C/ 400 °C

• move glass relative to absorber

• failure detection: increase in

heating power

• test

o until failure

o until 20 000 cycles reached


Accelerated aging / lifetime testing of REPAs

under power plant operation conditions:

• heat transfer fluid thermal oil

@ 300-450°C, 25bar

• external forces simulating receiver expansion

• rotational collector movement drive

• adjustable focal length

• monitoring of forces, torques and operation conditions during testing

Objectives

• REPA component qualification

• Investigation of failure mechanisms

• Development of standard REPA test procedures

Joint construction and operation by DLR and Ciemat at PSA

(Spring/Summer 2015)

Joint Test Facility for

Rotation and Expansion Performing Assemblies


Acellerated Ageing of Parabolic Trough Receiver

Overheating Test

• Acellerated ageing of absorber coating

• Absorber temp. up to 600°C

• 1000 h overheating time correlates to

aging over 25 years

Bellow Fatigue Test

• Testing of bellow durability

• Absorber mean temperature 200 °C

• Absorber temperature at bellow 400 °C

• 10 000 cycles (1 per sec) correlates to 25

years of receiver operation


a) Airborne camera vehicle during a test

flight at KONTAS test facility (PSA)

d) Slope deviation measured by QFly for KONTAS

collector

[mrad]

c) Photogrammetric determination of

camera and collector position

Qualification of Concentrators

Field Measurement: Qfly (optical and thermal)

b) IR Temperature measurement of receivers


Conclusion

• Further field data necessary to

• Understand failure mechanisms

• develop lifetime models

• develop accelerated ageing methods

• develop quality and testing standards

• Prestine samples to be stored for comparison

• First guidelines for testing standards under development (mirrors,

receivers, heliostats)

• Long term R&D to develop methodology for durability tests

• Test and qualification laboratories available


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