Flat-Plate Solar Collectors State-of-the-Art and Trends

Transcription

1 March 14-16, 2012 Mikkeli (Finland) Sebastian Brandmayr Prof. Wilfried Zörner Flat-Plate Solar Collectors State-of-the-Art and Trends

2 Outline Technical Design of Flat-Plate Collectors Solar Collector Efficiency Collector Parts Transparent Cover Absorber Design Thermal Insulation Casing Collector Production 2

3 Technical Design of Flat-Plate Collectors Solar Collector Efficiency Collector Parts Transparent Cover Absorber Design Thermal Insulation Casing Collector Production 3

4 Technical Design of Flat-Plate Collectors (1) Flat-Plate Collector Principle Absorption of Solar Radiation by a (Black) Hose or Plate Conversion of Radiation into Heat Heat Transportation to the Consumer or the Storage Low Temperature Solar Thermal Collectors Domestic Hot Water Supply Space Heating Industrial Process Heat (< 100 C) Do-It-Yourself Collector in Germany 4

5 Technical Design of Flat-Plate Collectors (2) Solar Collector Parts Typical Flat-Plate Collector Design Layout Transparent Cover Absorber 5 Casing Insulation Fluid Channels

6 Technical Design of Flat-Plate Collectors Solar Collector Efficiency Collector Parts Transparent Cover Absorber Design Thermal Insulation Casing Collector Production 6

7 Solar Collector Efficiency (1) Thermal Power of Collectors Energy Conversion Efficiency up to 80 % Energetic Losses by Reflexion Heat Conduction Convection Thermal Radiation 7

8 Solar Collector Efficiency (2) Optical and Heat Conduction Losses Optical Losses Transmission Losses through the Transparent Cover by Absorption and Reflexion ( Transmission Coefficient t ) Limited Absorption of the Incident Solar Radiation at the Absorber ( Absorption Coefficient α ) Heat Conduction Transparent Cover ( Small Portion) Absorber Fastening Elements and Casing Thermal Insulation ( Contact of Absorber and Insulation) 8

9 Solar Collector Efficiency (3) Convective and Radiative Heat Losses Internal Convection Mechanisms Hot Absorber and Cold Transparent Cover External Convection Mechanisms Wind Rain, (Snow) Thermal Radiation Depending on the Emission Behaviour ( Emission Coefficient e ) Long Wave (Infrared) Radiation Temperature Distribution in a Solar Collector 9

10 Solar Collector Efficiency (4) Collector Efficiency total QN G A e Q0 Qth 100[%] 100[%] G A A e Reference Area (Aperture Area) [m²] G Global Irradiation [W/m²] Q N Thermal Output [W] Q th Thermal Losses [W] Q 0 Optical Input [W] e 10

11 Technical Design of Flat-Plate Collectors Solar Collector Efficiency Collector Parts Transparent Cover Absorber Design Thermal Insulation Casing Collector Production 11

12 Ruesch F., Brunold S. (2008) Langzeitalterungsuntersuchung an Abdeckungsmaterialien für thermische Sonnenkollektoren Schlussbericht [WWW] Available at: publ/freibewitterung_bericht_ pdf [Accessed: 01/03/12] Transparent Cover (1) Materials Glass Polymers Approved Long-Term Stability (Optical + Mechanical Properties) High Weight Light Weight Long-Term Stability of Optical Properties Mechanical Properties ( Hail, Snow Loads) Coating of Polymers to Enhance Stability (in Research) Polycarbonate Samples after 20 Years of Exposure in Rapperswil (CH) 12

13 Frei U. (2012) Antireflective Coated Glass for Thermal Collectors pros, cons and risks. 3rd SMEThermal Solar Thermal Materials, Equipment and Technology Conference, Berlin, 2012 Transparent Cover (2) Optical Properties Antireflective Coated Glass Pro: Collector Efficiency +4 % 2x AR Coating Cons: Long-Term Stability Unknown Higher Temperatures: Redesign of Collector Necessary Without AR Coating 13 Cover Thickness [mm] Weight [kg/m²] Transmission Coefficient Durability Standard Glass, Heat Strengthened Non-Ferrous Glass, Heat Strengthened Antireflective Coated Glass, Heat Strengthened o/+ Polycarbonate Plate o PMMA (Acryl Glas) o PTFE-film o

14 Absorber Design (1) Absorber: Heart of the Solar Collector High Temperature Range (Stability): C Pressure- and Corrosion-Resistance Differences in Pipe Routing Meander (Serpentine) Harp Materials Classic: Copper/Copper Nowadays: Copper/Aluminum Recently: Aluminum/Aluminum 14

15 Absorber Design (2) Absorber Types Fin-Pipe Geometry Most Common Design Pipes and Absorber Welded Ultrasonic Welded Absorber (Cu/Cu) Laser Welded Absorber (Cu/Al) Roll Bond Absorber 2 Joined Al-Plates High Efficient Hydraulic Design Possible 3D-Batch-Coating Necessary Corrugated Pattern Absorber ( Nearly no Market Share) Volumetric Roll Bond Absorber (Al/Al) 15

16 N.N. (2012) Homepage SavoSolar Oy [WWW] Available at: [Accessed: 01/03/12] Absorber Design (3) Absorber Coatings (1) Distribution of Solar Energy on Earth Incoming: 98 % Energy Below 3,000 nm Energetic Losses: 99 % Grey or Black Body Radiation above 3,000 nm Goal of Thermal Absorbers High Absorption in Visible Range High Reflectance in Infrared Range Solar Radiation / Optical Behaviour of High Selective Coatings 16

17 Absorber Design (4) Absorber Coatings (2) Black Paint Absorption Coefficient = Emission Coefficient Low System Performance Steel Absorber with Black Chrome Coating (Obsolete) Black Chrome (Galvanic Layer) High Absorption / Medium Emission Durable Coating Sufficient for Southern Climates 17 High Selective Coatings ( Blue Coatings ) High Absorption / Low Emission Environmentally Friendly Production Standard Delivery Format: Metal Coil (no Batch Process) Prototype Collector (100% Aluminium)

18 Thermal Insulation Functions Insulation of the Casing to Minimize Thermal Losses Backside Insulation mm Side Insulation (Frame Collector) 20 mm Stagnation Temperature up to 230 C Mineral Wool Standard Foam (PU), Not Temperature Stable Advanced Foam Materials, Conduction < W m -1 K -1, (Still) Expensive Mineral Wool Insulation 18

19 Casing Technical Aspects Functionality Integration of Insulation and Absorber Secure Mounting of Transparent Cover ( Gluing or Clamping) Adaptor for Collector Mounting System Durability against Environmental Loads ( Wind, Snow) Collector Mounting System (SunWin Energy Systems GmbH) Design Frame (Profile with Edge Connection) Trough (Deep-Drawn) Aluminium Deep-Drawn Trough 19

20 Technical Design of Flat-Plate Collectors Solar Collector Efficiency Collector Parts Transparent Cover Absorber Design Thermal Insulation Casing Collector Production 20

21 Müller H., Zörner W. (2008) State-of-the-Art Collector Production An Overview, 1st SMEThermal Solar Thermal Materials, Equipment and Technology Conference, Berlin, 2010 Glass Cover Glass Cover Back Plate Frame Parts Insulation Absorber Glass Cover Packaging Material Finished Collectors Collector Production (1) Consumables + Tools Semi-Finished and Finished Material Roll Conveyor System Flow of Material Movement of Semi-Finished and Finished Products Section 1: Processing of Pre-Fabricated Material (Glass Cover, Frame Profiles,...) Section 2: Assembly of Frame and Back Plate Section 3: Assembly of Absorber and Insulation Section 4: Assembly of Glass Cover Section 5: Assembly of Glass Cover Fixation, Finish of Absorber Hydraulics Section 6: Packaging and Palletising Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 21

22 Müller H., Zörner W. (2008) Kurzstudie Produktionsprozesse für die Deutsche Solarthermie-Technologie Plattform [WWW] Available at: [Accessed: 15/01/2012] Collector Production (2) Perspective Cycle Time: 60 s Output per Year: Collectors More and More Automated Sections Target: Increase of Capacity / Efficiency and Quality (Not a Reduction of Personnel) 22

23 Many thanks for your kind attention! Any questions? 23