HIGH TEMPERATURE MEASUREMENT BY THERMOGRAPHY ON CSP

Transcription

1 HIGH TMPRATUR MASURMNT BY THRMOGRAPHY ON CSP Dr. Jesús Ballestrín CIMAT-Plataforma Solar de Almería (SPAIN) 4 th SFRA Summer School 1

2 Visible range Snake IR vision 2

3 CCD spectral response Human eye response 3

4 Visible range Infrared range 4

5 Visible range Infrared range 5

6 THRMAL RADIATION All matter with a temperature greater than absolute zero emits thermal radiation. This radiation increases with temperature. Radiation is the principal way that heat and energy travel through the universe. Solar Solar: m 5760 K Solar Thermal 6

7 1. A blackbody absorbs all incident radiation, regardless of wavelenght and direction. 2. For a certain temperature and wavelenght, no surface can emit more energy than a blackbody. 3. Altough the radiation emitted by a blackbody is a function of wavelenght and temperature, it is independient of direction. That is, the blackbody is a diffuse emitter. 7

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9 Planck s law Stefan-Boltzmann s law b ( e C 2 / n T C1 5 1) n 2 [ W m 2 nm 1 ] 0 d b 0 b d T [ W m 4 2 ] b 0 max T [ nm K ] Wien's displacement law Irradiance, W m -2 nm -1 9

10 b d [ W m K 4 T ] 10

11 11 ), ( ),,, ( ),,, (,,, T I T I T b e mission from real surfaces. mittance Ɛ ), ( ), ( ), (, T T T b Hemispherical spectral ) ( ), ( ), ( ) ( 0, T d T T T b b Hemispherical

12 IR calibration 12

13 Kirchoff s law Thermal equilibrium (T), (,,, T ), (,,, T ) Opaque 1 A good thermal emitter is a bad reflector and viceversa Perkin lmer spectrophotometer in the nm Nicolet Magna IR spectrophotometer in the nm 13

14 Temperature uncertainty versus mittance uncertainty T 4 dt dt d d 1 dt T d dt T 1 T 1 d 4 12 % 3% T 14

15 Surface temperature measurement High temperatures (> 2000 ºC) Low confidence on contact sensors. IR detectors: pyrometers and cameras. 15

16 Reflected solar radiation (Gr) Solar radiation Detector (Pyrometer or IR camera) Sample Thermal radiation (th) 16

17 Solar furnace diagram 17

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20 1000 Mirror reflectance 1,0 0,9 Spectral irradiance [W m -2 nm -1 ] ,1 0,01 Concentrated Solar Radiation DNI quartz 5mm B.B. at 1100 K B.B. at 700 K B.B. at 500 K 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 Reflectance / Transmittance 0, [nm] 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. 20

21 Band pass filters Spectral irradiance [W m -2 nm -1 ] Mirror reflectance Reflected DNI 1900 nm 2410 nm Quartz 5mm 2710 nm 1100 K 700 K 3320 nm 500 K 4275 nm 4720 nm Reflectance / Transmittance [%] Wavelength[nm] Camera transducer: InSb nm 21

22 rror calculations 1) ( r FILTR ) ( th FILTR G r FILTR th FILTR ) th FILTR G r FILTR th FILTR 2) dt T 1 4 d FILTR FILTR r 1 ( T ) r ( FILTR 4 ) r (T) 5% 22

23 Results Filter Measuring temperature range Attenuation for solar radiation Quartz transmittance (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 % 23

24 Thermal radiation attenuation Beer s Law L 0 e C L 24

25 Thermal radiation attenuation Atmospheric transmissivity test Temperature measurement vs. distance Temperature [K] Black Body Temperature F3320 ([K]) F4720 ([K]) F4275 ([K]) F2700 ([K]) Distance [m] 25

26 rror for each selected filter 1000 Filter centered at 3320 nm Reflectivity 90% 1000 Filter centered at 4720 nm Reflectivity 90% Reflectivity 70% 100 Reflectivity 70% Relative error [%] 10 1 Reflectivity 30% Reflectivity 50% Relative error [%] 10 1 Reflectivity 50% Reflectivity 30% Reflectivity 10% Reflectivity 10% Temperature [K] Temperature [K] 26

27 Measurements without quartz window Both filters can be used: Filter centered at 3320 nm. Filter centered at 4720 nm. Photography Thermography at 3320 nm. 27

28 Temperature correction for quartz window Spectral Irradiance [W m -2 nm -1 ] camera camera filter filter Quartz transmittance 5 mm 1900 nm 2410 nm DNI 2710 nm 3320 nm quartz Wavelength[nm] 4275 nm 4720 nm Transmittance [%] T T W 4 4 filter T filter 4 T W quartz quartz 28

29 Measurements with quartz window Filter centered at 4720 nm. Measurement of the quartz window Photography Thermography at 4720 nm 29

30 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. 30

31 Development of a Radiometry Laboratory Spherical black body: ºC (± 0.25 %) Cylindrical black body: ºC (± 0.25 %) Pyrometer: ºC (± 0.30 %) Solar blind pyrometer: ºC (± 0.30 %) Pass Band Filter: 1390 ± 20 nm Two-color pyrometer: ºC (± 0.50 %) Two-color pyrometer: ºC (± 0.50 %) 31

32 OBJTIVS OF TH LABORATORY Periodic calibration of heat flux sensors (Present) Periodic calibration of IR pyrometers and cameras (Present) mittance characterization of material surfaces at high temperatures (Future) 32