Central Receiver Systems - CRS1	               GEEN 4830 – ECEN 5007	   14/7/10
Solar Thermal Power Plant.       Basic configuration                Beam irradiance	                                     C...
Central Receiver Systemhttp://www1.eere.energy.gov/solar/power_towers.html	  3	                                GEEN 4830 –...
CRS (Gema Solar, Molten salts)4	               GEEN 4830 – ECEN 5007	   14/7/10
CRS   (Phoebus, Open air volumetric receiver)5	              GEEN 4830 – ECEN 5007	   14/7/10
Collector System (concentrator)6	                 GEEN 4830 – ECEN 5007	   14/7/10
Heliostat field}  The concentrator is the “heliostat field”, a Fresnel    concentrator}  Main elements        }    Heli...
The heliostat       }    “an instrument consisting of a mirror mounted on an axis moved             by clockwork by which...
Heliostat                                                       Incident ray	                                             ...
Burning mirror, Hoesen (18th century)10	                GEEN 4830 – ECEN 5007	   14/7/10
Glass – metal heliostat11	              GEEN 4830 – ECEN 5007	   14/7/10
Heliostat12	               GEEN 4830 – ECEN 5007	   14/7/10
Glass – metal heliostat13	                GEEN 4830 – ECEN 5007	   14/7/10
Glass – metal heliostats14	                GEEN 4830 – ECEN 5007	   14/7/10
Stretched membrane heliostats15	               GEEN 4830 – ECEN 5007	   14/7/10
Stretched membrane heliostats16	              GEEN 4830 – ECEN 5007	   14/7/10
Stretched membrane heliostats17	              GEEN 4830 – ECEN 5007	   14/7/10
Heliostat field layout        }    Surround field        }    North (south) field        }    Secondary concentration  ...
North field                             1000                             800                             600              ...
Surrounding field20	               GEEN 4830 – ECEN 5007	   14/7/10
Geometrical performance of heliostats21	             GEEN 4830 – ECEN 5007	   14/7/10
Cosine factor                        Yearly average cosine factor for a                        north heliostat field	22	   ...
Reflectivity        }    Reflectivity of a new, clean mirror ≈ 0.90 ÷ 0.9423	                                    GEEN 483...
Shading and blocking                                           Shading & blocking        Shading        Blocking24	       ...
Air transmittance                                           Air transmittance25	               GEEN 4830 – ECEN 5007	     ...
Mirror quality}      Heliostat facets are spherically curved        }    For large focal distances, a parabolic surface ...
Mirror quality                                         σ D = σ S + σ sp + σ c2                                           2...
Distortion}  Spherical reflectors generate distortion of the image}  Dependent on time (relative position sun-heliostat)...
Spillage29	              GEEN 4830 – ECEN 5007	   14/7/10
Receiver system}      Function}      Components}      Types of receivers}      Working fluids      30	                ...
CRS – Sistema Receptor31	               GEEN 4830 – ECEN 5007	   14/7/10
Tipos de receptores32	               GEEN 4830 – ECEN 5007	   14/7/10
Cavity receivers33	              GEEN 4830 – ECEN 5007	   14/7/10
Cavity receivers34	              GEEN 4830 – ECEN 5007	   14/7/10
Receptor - Fluidos de trabajo        }    Características térmicas apropiadas: capacidad térmica,              entalpía d...
Molten salt cavity receiver36	             GEEN 4830 – ECEN 5007	   14/7/10
External, cylindrical receiver37	             GEEN 4830 – ECEN 5007	   14/7/10
External, cylindrical receiver38	             GEEN 4830 – ECEN 5007	   14/7/10
External, cylindrical receiver39	             GEEN 4830 – ECEN 5007	   14/7/10
Tubular receiver (boiler)40	                GEEN 4830 – ECEN 5007	   14/7/10
Heat transfer characteristics of tubular andvolumetric receivers41	            GEEN 4830 – ECEN 5007	   14/7/10
Volumetric receivers42	            GEEN 4830 – ECEN 5007	   14/7/10
Volumetric receivers43	            GEEN 4830 – ECEN 5007	   14/7/10
Detail of a volumetric absorber (wire mesh)44	            GEEN 4830 – ECEN 5007	   14/7/10
Detail of a volumetric absorber(ceramic cups)45	            GEEN 4830 – ECEN 5007	   14/7/10
Working fluids46	            GEEN 4830 – ECEN 5007	   14/7/10
Working fluids for CRS}      Water / steam        }    Saturated steam        }    Superheated steam}      Molten salt...
Comparison of HTF’s48	          GEEN 4830 – ECEN 5007	   14/7/10
Power conversion system}      Rankine cycle (steam turbine)}      Brayton cycle (gas turbine)}      Combined cycle (gas...
CRS: pros and cons.}      Pros:        }    Ability to achieve high temperatures        }    Wide industrial base for m...
Energy Balance of Central ReceiverSystems51	            GEEN 4830 – ECEN 5007	   14/7/10
High concentration concepts}      Secondary concentration        }    Increase flux density on the absorber        }   ...
Secondary concentrators}      REFOS Project (DLR)      53	                   GEEN 4830 – ECEN 5007	   14/7/10
SCOT (Secondary Concentrator OpticsTower)}      Weizmann Institute (Israel)      54	                     GEEN 4830 – ECEN...
SCOT (Secondary Concentrator OpticsTower)55	           GEEN 4830 – ECEN 5007	   14/7/10
Beam Down56	       GEEN 4830 – ECEN 5007	   14/7/10
Solar Furnaces57	            GEEN 4830 – ECEN 5007	   14/7/10
Solar Furnaces58	            GEEN 4830 – ECEN 5007	   14/7/10
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Ecen 5007 lecture 7

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Ecen 5007 lecture 7

  1. 1. Central Receiver Systems - CRS1 GEEN 4830 – ECEN 5007 14/7/10
  2. 2. Solar Thermal Power Plant. Basic configuration Beam irradiance Concentrator Concentrated irradiance Electricity Receiver Thermal energy Thermal Storage Power conversion system Fossil fuel Boiler Biomass 2 GEEN 4830 – ECEN 5007 14/7/10
  3. 3. Central Receiver Systemhttp://www1.eere.energy.gov/solar/power_towers.html 3 GEEN 4830 – ECEN 5007 14/7/10
  4. 4. CRS (Gema Solar, Molten salts)4 GEEN 4830 – ECEN 5007 14/7/10
  5. 5. CRS (Phoebus, Open air volumetric receiver)5 GEEN 4830 – ECEN 5007 14/7/10
  6. 6. Collector System (concentrator)6 GEEN 4830 – ECEN 5007 14/7/10
  7. 7. Heliostat field}  The concentrator is the “heliostat field”, a Fresnel concentrator}  Main elements }  Heliostat }  Control System 7 GEEN 4830 – ECEN 5007 14/7/10
  8. 8. The heliostat }  “an instrument consisting of a mirror mounted on an axis moved by clockwork by which a sunbeam is steadily reflected in one direction” }  Basic components }  Reflecting surface }  Structure and tracking mechanism }  Control system }  Typology: }  Glass - metal }  Stretched membrane }  Size: 1 m2 to 150 m28 GEEN 4830 – ECEN 5007 14/7/10
  9. 9. Heliostat Incident ray Reflected ray Back support structure Elevation drive Reflecting surface Azimuth drive 9 GEEN 4830 – ECEN 5007 14/7/10
  10. 10. Burning mirror, Hoesen (18th century)10 GEEN 4830 – ECEN 5007 14/7/10
  11. 11. Glass – metal heliostat11 GEEN 4830 – ECEN 5007 14/7/10
  12. 12. Heliostat12 GEEN 4830 – ECEN 5007 14/7/10
  13. 13. Glass – metal heliostat13 GEEN 4830 – ECEN 5007 14/7/10
  14. 14. Glass – metal heliostats14 GEEN 4830 – ECEN 5007 14/7/10
  15. 15. Stretched membrane heliostats15 GEEN 4830 – ECEN 5007 14/7/10
  16. 16. Stretched membrane heliostats16 GEEN 4830 – ECEN 5007 14/7/10
  17. 17. Stretched membrane heliostats17 GEEN 4830 – ECEN 5007 14/7/10
  18. 18. Heliostat field layout }  Surround field }  North (south) field }  Secondary concentration }  Secondary concentrator optics tower (SCOT)18 GEEN 4830 – ECEN 5007 14/7/10
  19. 19. North field 1000 800 600 400 200 0 -600 -400 -200 0 200 400 60019 GEEN 4830 – ECEN 5007 14/7/10
  20. 20. Surrounding field20 GEEN 4830 – ECEN 5007 14/7/10
  21. 21. Geometrical performance of heliostats21 GEEN 4830 – ECEN 5007 14/7/10
  22. 22. Cosine factor Yearly average cosine factor for a north heliostat field 22 GEEN 4830 – ECEN 5007 14/7/10
  23. 23. Reflectivity }  Reflectivity of a new, clean mirror ≈ 0.90 ÷ 0.9423 GEEN 4830 – ECEN 5007 14/7/10
  24. 24. Shading and blocking Shading & blocking Shading Blocking24 GEEN 4830 – ECEN 5007 14/7/10
  25. 25. Air transmittance Air transmittance25 GEEN 4830 – ECEN 5007 14/7/10
  26. 26. Mirror quality}  Heliostat facets are spherically curved }  For large focal distances, a parabolic surface can be approximated by an spherical surface of radius r = 2f (f: focal distance). 26 GEEN 4830 – ECEN 5007 14/7/10
  27. 27. Mirror quality σ D = σ S + σ sp + σ c2 2 2 2 Ideal spherical curvature σ D = σ S + σ sp + σ c2 2 2 2 Spherical curvature, with waviness27 GEEN 4830 – ECEN 5007 14/7/10
  28. 28. Distortion}  Spherical reflectors generate distortion of the image}  Dependent on time (relative position sun-heliostat) Summer solstice, 7:30 a.m. Summer solstice, 7:30 p.m. Summer solstice, noon 28 GEEN 4830 – ECEN 5007 14/7/10
  29. 29. Spillage29 GEEN 4830 – ECEN 5007 14/7/10
  30. 30. Receiver system}  Function}  Components}  Types of receivers}  Working fluids 30 GEEN 4830 – ECEN 5007 14/7/10
  31. 31. CRS – Sistema Receptor31 GEEN 4830 – ECEN 5007 14/7/10
  32. 32. Tipos de receptores32 GEEN 4830 – ECEN 5007 14/7/10
  33. 33. Cavity receivers33 GEEN 4830 – ECEN 5007 14/7/10
  34. 34. Cavity receivers34 GEEN 4830 – ECEN 5007 14/7/10
  35. 35. Receptor - Fluidos de trabajo }  Características térmicas apropiadas: capacidad térmica, entalpía de cambio de fase, estado a temperatura ambiente }  No corrosivo, tóxico o inflamable }  Abundante, barato, tecnología de manejo asequible... }  No existe el fluido perfecto: hay que llegar a compromisos35 GEEN 4830 – ECEN 5007 14/7/10
  36. 36. Molten salt cavity receiver36 GEEN 4830 – ECEN 5007 14/7/10
  37. 37. External, cylindrical receiver37 GEEN 4830 – ECEN 5007 14/7/10
  38. 38. External, cylindrical receiver38 GEEN 4830 – ECEN 5007 14/7/10
  39. 39. External, cylindrical receiver39 GEEN 4830 – ECEN 5007 14/7/10
  40. 40. Tubular receiver (boiler)40 GEEN 4830 – ECEN 5007 14/7/10
  41. 41. Heat transfer characteristics of tubular andvolumetric receivers41 GEEN 4830 – ECEN 5007 14/7/10
  42. 42. Volumetric receivers42 GEEN 4830 – ECEN 5007 14/7/10
  43. 43. Volumetric receivers43 GEEN 4830 – ECEN 5007 14/7/10
  44. 44. Detail of a volumetric absorber (wire mesh)44 GEEN 4830 – ECEN 5007 14/7/10
  45. 45. Detail of a volumetric absorber(ceramic cups)45 GEEN 4830 – ECEN 5007 14/7/10
  46. 46. Working fluids46 GEEN 4830 – ECEN 5007 14/7/10
  47. 47. Working fluids for CRS}  Water / steam }  Saturated steam }  Superheated steam}  Molten salts}  Air }  Pressurized }  Atmospheric}  Sodium}  Thermal oils 47 GEEN 4830 – ECEN 5007 14/7/10
  48. 48. Comparison of HTF’s48 GEEN 4830 – ECEN 5007 14/7/10
  49. 49. Power conversion system}  Rankine cycle (steam turbine)}  Brayton cycle (gas turbine)}  Combined cycle (gas turbine + steam turbine)}  Stirling engines}  (MHD) 49 GEEN 4830 – ECEN 5007 14/7/10
  50. 50. CRS: pros and cons.}  Pros: }  Ability to achieve high temperatures }  Wide industrial base for most components }  Multiple technological options }  Technologically proven }  Multiple thermal energy storage options }  High potential for improved effciency or cost reduction}  Cons.: }  Complexity }  Short commercial record }  Best technology still undefined 50 GEEN 4830 – ECEN 5007 14/7/10
  51. 51. Energy Balance of Central ReceiverSystems51 GEEN 4830 – ECEN 5007 14/7/10
  52. 52. High concentration concepts}  Secondary concentration }  Increase flux density on the absorber }  Reduce requirements for primary concentrator (heliostats)}  Secondary Concentrator Optics Tower }  The receiver can be placed at the ground level}  Solar Furnaces }  Very high concentration ratios }  Combine a field of flat heliostats and a parabolic concentrator }  Not for electricity generation 52 GEEN 4830 – ECEN 5007 14/7/10
  53. 53. Secondary concentrators}  REFOS Project (DLR) 53 GEEN 4830 – ECEN 5007 14/7/10
  54. 54. SCOT (Secondary Concentrator OpticsTower)}  Weizmann Institute (Israel) 54 GEEN 4830 – ECEN 5007 14/7/10
  55. 55. SCOT (Secondary Concentrator OpticsTower)55 GEEN 4830 – ECEN 5007 14/7/10
  56. 56. Beam Down56 GEEN 4830 – ECEN 5007 14/7/10
  57. 57. Solar Furnaces57 GEEN 4830 – ECEN 5007 14/7/10
  58. 58. Solar Furnaces58 GEEN 4830 – ECEN 5007 14/7/10

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