High Temperature Measurementby Thermography on CSP, Jesús ...

Dr. Jesús BallestrínCIEMAT-Plataforma Solar de Almería (SPAIN)

4th SFERA Summer School May 15-16, 2013. Hornberg Castle, GERMANY

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HIGH TEMPERATURE MEASUREMENTBY THERMOGRAPHY ON CSP


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Visible range Snake IR vision


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CCD spectral responseHuman eye response

4th SFERA Summer SchoolMay 15-16, 2013. Hornberg Castle, GERMANY

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Visible range Infrared range


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Visible range Infrared range


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Radiation is the principal way that heat and energy travelthrough the universe.

THERMAL RADIATIONAll matter with a temperature greater than absolute zero emitsthermal radiation. This radiation increases with temperature.

Solar

Solar: 0.1- 4 m5760 K

Solar Thermal


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1. A blackbody absorbs all incident radiation, regardlessof wavelenght and direction.

2. For a certain temperature and wavelenght, no surface canemit more energy than a blackbody.

3. Altough the radiation emitted by a blackbody is a function ofwavelenght and temperature, it is independient of direction.That is, the blackbody is a diffuse emitter.


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0

bE

0d

][)1(

1225/

12

nmmW

neCE TnCb

Planck’s law

][ 2

0

4

mWTdEE bb

Stefan-Boltzmann’s law

][10898.2 6max KnmT

Wien's displacement law Irrad

ianc

e, W

m-2

nm

-1


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][1067.5 4284

0

KmW

T

dE b


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),(),,,(

),,,(,

,, TI

TIT

b

e

Emission from real surfaces. Emittance Ɛ

),(),(),(

, TETET

b

Hemispherical spectral

)(

),(),()( 0 ,

TE

dTETT

b

b

Hemispherical


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IR calibration


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1

Kirchoff’s law

(T)

),,,(),,,( ,, TT

Opaque

Thermal equilibrium

“A good thermal emitter is a bad reflector and viceversa”

• Perkin–Elmer spectrophotometer in the 175–3300 nm

• Nicolet Magna IR spectrophotometer in the 1350–28500 nm


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ET 4

d

TdT

41

dddTdT

dTEdT 324

1

• Temperature uncertainty versus Emittance uncertainty

T1

12 % 3% T


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Surface temperature measurement

• High temperatures (> 2000 ºC)

• Low confidence on contact sensors.

• IR detectors: pyrometers and cameras.


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Detector(Pyrometer or IR camera)

Sample

Thermal radiation (Eth)

Solar radiation

Reflected solar radiation (Gr)


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Solar furnace diagram


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0 1000 2000 3000 4000 5000

0,01

0,1

1

10

100

1000

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

DNI

Concentrated Solar Radiation

Ref

lect

ance

/ Tr

ansm

ittan

ce

Spec

tral i

rrad

ianc

e [W

m-2 n

m-1]

[nm]

quartz 5mm

B.B. at 500 K

B.B. at 700 K

B.B. at 1100 K

Mirror reflectance

Atmospheric absorption solar bands in a concentrated solar spectrum based on a MODTRAN simulation,black body radiance at several temperatures, quartz transmittance and mirror reflectance.


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0 1000 2000 3000 4000 50000.01

0.1

1

0

10

20

30

40

50

60

70

80

90

100

700 K

1100 K

R eflected D N I

Ref

lect

ance

/ T

rans

mitt

ance

[%

]

Spec

tral

irra

dian

ce [W

m-2

nm

-1]

W avelength [nm ]

500 K

4275

nm

2710

nm19

00 n

m

M irror reflectance

Q uartz 5m m

4720

nm

3320

nm

2410

nm

Band‐pass filters

Camera transducer: InSb 1500-5000 nm


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Error calculations

FILTERth

FILTERr

FILTERth

FILTERthFILTERrFILTERthFILTERr E

GE

EGEE

)()(

FILTER

FILTER

EdE

TdT

41

)(41)( FILTERrr ET

1)

2)

r(T) ≤ 5%


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Results

Filter Measuring temperature range

Attenuation for solar radiation

Quartztransmittance

(5 mm) = 1900 nm 1080 K ≤ T Atmospheric absorption 93 % = 2410 nm 2000 K ≤ T No attenuation 92 %

= 2710 nm Valid for any T Atmospheric absorption 91 %

= 3320 nm 600 K ≤ T Low reflectivity of the mirrors 86 %

= 4275 nm Valid for any T Atmospheric absorption + Low reflectivity of the mirrors 9 %

= 4720 nm 380 K ≤ T Low reflectivity of the mirrors 0 %


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Thermal radiation attenuation

Beer’s Law

LCL eEE 0


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Thermal radiation attenuation

3.90 3.95 4.00 4.05 4.10 4.15 4.20 4.25 4.30840

845

850

855

860

865

870

875

880

885

890

895

Distance [m]

Tem

pera

ture

[K]

Atmospheric transmissivity test Temperature measurement vs. distance

Black Body Temperature F3320 ([K]) F4720 ([K]) F4275 ([K]) F2700 ([K])


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Error for each selected filter

400 600 800 1000 1200 140016000.01

0.1

1

10

100

1000

Reflectivity 70%

Reflectivity 30%

Reflectivity 50%

Reflectivity 10%

Reflectivity 90%

Rel

ativ

e er

ror [

%]

Temperature [K]

Filter centered at 3320 nm

400 600 800 1000 1200 1400 16000.01

0.1

1

10

100

1000

Temperature [K]

Rel

ativ

e er

ror

[%]

Reflectivity 70%

Reflectivity 30%

Reflectivity 50%

Reflectivity 10%

Reflectivity 90%

Filter centered at 4720 nm

1


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Measurements without quartz window

• Both filters can be used:

Filter centered at 3320 nm. Filter centered at 4720 nm.

Photography Thermography at 3320 nm.


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Temperature correction for quartz window

filtercamera EE

quartzfiltercamera EE 4

filterE

T

4 quartzfilter

W

ET

4quartz

WTT

2000 3000 4000 5000

1E-3

0.01

0.1

1

0

10

20

30

40

50

60

70

80

90

100

DNI Tra

nsm

ittan

ce [%

]

Spec

tral

Irra

dian

ce [W

m-2

nm

-1]

Wavelength[nm]

0.001

4275

nm

2710

nm

1900

nm

Quartz transmittance 5 mm

4720

nm

3320

nm

2410

nm


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Measurements with quartz window

Filter centered at 4720 nm.

• Measurement of the quartz window

Thermography at 4720 nmPhotography


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Conclusions

Using the pass‐band filters centered at 3320 and 4720 nm

the measurements are not affected by the reflected solar radiation or by the atmospheric attenuation

allows to measure through quartz windows allows to measure the temperature of the quartz windows the higher the surface temperature, the lower relative error in

the measurement

Nowadays, this camera is being used in the solar furnace of the Plataforma Solar de Almería.


Development of a Radiometry Laboratory

• Two-color pyrometer: 600-1400 ºC (± 0.50 %)

• Two-color pyrometer: 700-2000 ºC (± 0.50 %)

• Solar blind pyrometer: 500-2500 ºC (± 0.30 %)Pass Band Filter: 1390 ± 20 nm

• Spherical black body: 100-1000 ºC (± 0.25 %)

• Cylindrical black body: 300-1700 ºC (± 0.25 %)

• Pyrometer: 600-3000 ºC (± 0.30 %)

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• Periodic calibration of heat flux sensors (Present)

• Emittance characterization of material surfaces at high temperatures (Future)

• Periodic calibration of IR pyrometers and cameras (Present)

OBJETIVES OF THE LABORATORY

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High Temperature Measurementby Thermography on CSP, Jesús ...

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