Introduction to EN 12975-2 / ISO 9806 Dr. Stephan Fischer (SWT) Research and Testing Centre for Thermal Solar Systems (TZS) SWT Technologie Pfaffenwaldring 6, 70550 Stuttgart, Germany Email: fischer@itw.uni-stuttgart.de Internet: www. swt-technologie.de 1 Stephan Fischer 1 st Remark Revision of EN 12975 and ISO 9806 is on going Result will be a joined Standard EN ISO 9806 Pave the way for a further harmonisation of certification schemes 2 Stephan Fischer 1
Overview Internal pressure test High temperature test Exposure test Thermal shock tests internal/external Rain penetration Mechanical load tests Impact resistance test Freeze resistance test Thermal performance test 3 Stephan Fischer [1] Internal pressure tests for absorbers to assess the extent to which it can withstand the pressures which it might meet in service using organic absorbers, tests shall be carried out at elevated temperatures, because the pressure resistance of an organic absorber may be adversely affected as its temperature increased 4 Stephan Fischer 2
[1] Internal pressure tests for absorbers - test conditions inorganic absorbers (according to 5.2.1.3) inorganic absorbers shall be pressure-tested at ambient temperature within the range 5 C to 30 C test pressure shall be 1,5 times the maximum collector operating pressure specified by the manufacturer test pressure shall be maintained for 15 min 5 Stephan Fischer [1] Internal pressure tests for absorbers - test conditions organic absorbers (according to 5.2.2.3) global solar irradiance on collector plane surrounding air temperature test pressure shall be 1,5 times the maximum collector operating pressure specified by the manufacturer pressure shall be raised to the test pressure in equal stages of 20 kpa and maintained at each intermediate pressure for 5 min test pressure shall be maintained for at least 1 h 6 Stephan Fischer 3
[1] Internal pressure tests for absorbers 7 [1] Internal pressure tests for absorbers 8 4
[1] Internal pressure tests for absorbers 9 [1] Internal pressure tests for absorbers - evaluation (according to 5.2.1.4 and 5.2.2.4) inspection for: leakage swelling distortion reporting in combination with values of used pressure temperature and the duration of the test/ test periods 10 5
[2] High-temperature resistance test to assess rapidly whether a collector can withstand high irradiance levels without failures relevant failures are such as glass breakage, collapse of plastic cover, melting of plastic absorber, significant deposits on the collector cover from outgassing of collector material 11 [2] High-temperature resistance test test conditions (according to 5.3.3) global solar irradiance on collector plane surrounding air temperature surrounding air speed 12 6
[2] High-temperature resistance test evaluation (according to 5.3.4) visual inspection: degradation shrinkage outgasing distortion reporting in combination with: average values of solar irradiance on the collector plane surrounding air temperature and speed absorber temperature 13 [3] Exposure test indicates operating conditions during real service low-cost reliability test sequence collector can be settled, such that subsequent qualification tests are more likely to give repeatable results 14 7
[3] Exposure test test conditions (according to 5.4.3) 15 [3] Exposure test 16 8
Exposure test Anemometer Rain sensor Ambient temperatur sensor Pyranometer Box for data logger 17 [3] Exposure test evaluation (according to 5.4.4) visual inspection: degradation damage reporting in combination with: record of daily irradiation, record of surrounding air temperature and rain 18 9
[4] External thermal shock test sudden rainstorms on hot sunny days cause a severe external thermal shock assessing the capability of a collector to withstand thermal shocks without a failure 19 [4] External thermal shock test test conditions (according to 5.5.3) 20 10
External thermal shock test 21 [4] External thermal shock test evaluation (according to 5.5.4) inspection for: Cracking Distortion Condensation water penetration or loss of vacuum reporting in combination with solar irradiance surrounding air temperature absorber temperature water temperature water flowrate 22 11
[5] Internal thermal shock test on hot sunny days collectors can be exposed to a sudden intake of cold heat transfer fluid causing a severe internal thermal shock for example after a period of shutdown assessing the capability of a collector to withstand such thermal shocks without failure 23 [5] Internal thermal shock test test conditions (according to 5.6.3) 24 12
Internal thermal shock test 25 [5] Internal thermal shock test evaluation (according to 5.6.4) inspection for: cracking distortion deformation water penetration or loss of vacuum reporting in combination with solar irradiance, surrounding air temperature absorber temperature heat transfer fluid temperature heat transfer fluid flowrate 26 13
[6] Rain penetration test glazed collectors shall normally not permit the entry of either freefalling rain or driving rain through ventilation holes and drain holes assessing the extent to which glazed collectors are substantially resistant to rain penetration 27 [6] Rain penetration test test conditions (according to 5.7.3) 28 14
[6] Rain penetration test 29 [6] Rain penetration test 30 15
[6] Rain penetration test 31 [6] Rain penetration test evaluation (according to 5.7.3 and 5.7.4) inspection for water penetration according to one of the following methods: weighing method humidity measurement method condensation level method 32 16
[7] Freeze resistance test test is only for collectors, which are claimed to be freeze resistant assessing the extent to which water heating collectors can withstand freezing, and freeze thaw cycling two procedures: one for collectors which are claimed to be freeze-resistant when filled with water one for collectors which are claimed to resist freezing after being drained 33 [7] Freeze resistance test test conditions (according to 5.8.3) temperature of the content of the absorber shall be maintained at (-20+/-2 C) for at least 30 min during the thawing part of the cycle temperature is raised to above 10 C thawing part of the cycle shall be at least 30 min the collector shall be subjected to three freeze-thaw cycles 34 17
[7] Freeze resistance test evaluation (according to 5.8.4) inspection for: leakage brakage distortion deformation reporting in combination with: absorber temperature during the cycles times spent by the collector at the test temperatures tilt angle used for the test shall 35 [8] Mechanical load test positive pressure: wind and snow cause positive pressure load to the transparent cover of the collector and the collector box assessing the extent to which the collector is able to resist this positive pressure load negative pressure: assessing the extent to which the fixings between the collector cover and collector box are able to resist uplift forces caused by the wind 36 18
[8] Mechanical load test - test conditions (according to 5.9.1.3 and 5.9.2.3) increasing test pressure at maximum steps of 250 Pa test pressure shall be at least 1000 Pa increasing test pressure until a failure occurs or pressure gets up to the value specified by the manufacturer a failure can be destruction of the cover permanent deformation of the collector box or the fixings 37 [8] Mechanical load test 38 19
Mechanical load test Negative pressure test on transparent cover 39 Mechanical load test Positive pressure test on evacuated tubular collector 40 20
[8] Mechanical load test - evaluation (according to 5.9.1.4 and 5.9.2.4) 41 [9] Impact resistance test assessing the extent to which a collector can withstand the effects of heavy impacts caused by hailstones testing can be done by one of the follwoing methods Method 1: Using steel balls Method 2: Using ice balls 42 21
[9] Impact resistance test test conditions (according to 5.10.3) method 1: using steel balls: mass of steel ball: 150 g +/- 10 g series of test heights: 0,4m; 0,6m; 0,8m; 1,0m; 1,2m; 1,4m; 1,6m; 1,8m; 2m method 2: using ice balls: diameter of ice ball: 25 mm +/- 5 % mass of ice ball: 7,53 g +/- 5 % velocity: 23m/s +/- 5 % 43 Impact resistance test 44 22
[9] Impact resistance test evaluation (according to 5.10.4) inspection for damage reporting also height from which the steel ball was dropped (if method 1 is used) and the number of impacts whioch caued the damage 45 Collector performance measurement Indoor solar simulator (steady-state) outdoor (steady-state and quasi-dynamic) 46 Dominik Bestenlehner 23
Collector parameter The thermal performance of a collector is described by 6 parameter 1. The conversion factor F ()en 2. First order heat loss coefficient 3. second order heat loss coefficient 4. Incidence angle modifier for the beam irradiance 5. Incidence angle modifier for the diffuse irradiance 6. Effective collector capacity 47 Collector models according EN 12975-2 Written as useful output power: Steady-state: Q q F' ( ) A Quasi-dynamic: en G c Q q F'( ) A en 2 1 ( fl, m amb ) c2( fl, m amb ) ( ) G F'( ) c1 ( fl, m amb ) c2( fl, m amb ) K b b 2 en K c d 5 G d dt d m 48 24
Boundary conditions steady state test Global irradiance: 700 W/m 2 Diffuse fraction: 0,3 Incident angle: < 30 wind speed: 3 ± 1 m/s Deviation during measurement: inlet temperature: ± 0,1 K ambient temperature: ± 1 K mass flow: ± 1 % global irradiance: ± 50 W/m 2 49 Boundary conditions quasi dynamic test Global irradiance: 300 1100 W/m 2 Useful output power: 0 W Wind speed: 3 ± 1 m/s Deviation during measurement: inlet temperature: ± 1 K mass flow: ± 1 % 50 25
Collector efficiency Q Q use rd fl V fl c p, fl ( fl, out fl, in G A ) optical losses / G Testing method: Collector efficiency useful energy / G thermal losses /G Stagnation point Ω Stag Steady state: K,i ± 0,1 K Quasi-dynamic: K,i ± 1 K ' ( fl, m amb G A ) 51 Collector measurements according EN 12975-2 Efficiency: m c p fl, out fl, in AG a 0 1 ( fl, m amb ) ( fl, m a2 G G amb ) 2 Reduced temperature: fl, m G amb 52 26
Test Procedure (steady state) Measurements under clear sky 15 min pre-conditioning, 15 min average for one data point At least 4 different inlet temperatures with 4 data points One inlet temperature such that mean fluid temperature equals ambient temperature 3 K Maximum inlet temperature at least 80 C 53 Data evaluation (steady state) Measurements are taken through out the day Determination of the time periods the boundary conditions are fulfilled Extracting of data points via mean values The parameter set 0, a 1 and a 2 are determined by the least square method using e.g. ECXEL a 0 1 ( fl, m amb ) ( fl, m a2 G G amb ) 2 54 27
Test Procedure (quasi dynamic) Measurements under all sky conditions all day measurements At least 4 different inlet temperatures (four days) One inlet temperature such that mean fluid temperature equals ambient temperature 3 K Maximum inlet temperature at least 80 C 55 Data evaluation (quasi dynamic) Measurements are taken through out the day Determination of the time periods the boundary conditions are fulfilled The parameter set is determined by parameter identification Q q F'( ) A en ( ) G F'( ) c1 ( fl, m amb ) c2 ( fl, m amb ) K b b 2 en K c d 5 G d dm dt 56 28
Parameter identification multi linear regression (MLR), fast matrix operation dynamic parameter identification using iterative methods 57 Graphical presentation 2000 collector output per module [W] 1800 1600 1400 1200 1000 800 600 400 200 0 W peak 0 10 20 30 40 50 60 70 80 90 100 ( m - a ) [K] 58 29
Incidence angle modifier (IAM) sun Collector plane K b ( ) 0 0 0 IAM Model Collectors with symmetrical optics (e.g. most flat plate collectors) K b ( ) 1 b 0 1 cos( ) K b ( ) 1 tan ² 2 1 60 30
1.0 IAM isotropic collecktor Einfallswinkelkorrekturvermögen [-] Incidence angle modifier [-] 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 10 20 30 40 50 60 70 80 90 Einfallswinkel [ ] Incidence angle [ ] IAM Model Collectors with asymmetrical optics (e.g. CPC, PTC etc.) Longitudinal plane L T Transversal plane Sun s Collektor plane Transversal direction East-West direction K b Longitudinal direction North-South direction ( ) Kb ( l, t ) Kb ( l,0) Kb (0, t ) 62 31
1,6 IAM bi-axialer collector Transversales Einfallswinkelkorrekturvermögen [-] Transversal Incidence angle modifier [-] 1,4 1,2 1 0,8 0,6 0,4 0,2 0 0 10 20 30 40 50 60 70 80 90 Transversal Transversaler incidence Einfallswinkel angle [ ] [ ] Example biaxial IAM K K 0 5 20 25 30 40 50 55 60 90 b ( l,0) b ( t 0, ) K b 1.00 1.00 0.96 0.86 0.56 0.38 0.25 0.15 0.0 0.0 1.00 1.00 0.99 0.98 0.97 0.96 0.90 0.84 0.77 0.0 ( ) Kb ( l, t ) Kb ( l,0) Kb (0, t ) K K b b ( 51) K (20,50) b ( 51) K (50,20) b 0.86 0.25 64 32
How to measure IAM Tracked collector using steady-state method drawback changing tilt results in changing effciency Fixed collector using quasi-dynamic procedure 65 Thank you 66 33