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Solar Cooling

Solar Cooling

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Solar Cooling

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  1. Solar Cooling www.sara-project.net

  2. Plan Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Introduction : Why & What is Solar Cooling • Thermodynamic basics • Conventional Cooling Cycle • Thermal Solar Cooling Techniques 3.1. Absortion Cooling 3.2 Adsortion Cooling 3.3 Dessicant refrigeration • Using Solar Energy in Cooling Cycle • Consumption, performances and costs • Comparative assessment • COP • Solar collectors used • Investment cost • Performance data • Consumption of auxiliary equipment • Water consumption

  3. What’s Solar Cooling? Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 • The core idea is to use the solar energy directly to produce chilled water. • The high temperature required by absorption chillers is provided by solar troughs. • The system doesn’t require “strategic” materials (like in PV systems) and has peak production in the moment of peak demand. Chilled water Heat Transfer Fluid

  4. Why Solar Cooling? Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 • Dramatic increase of air conditioning since the early 80ies • Cost of energy • Issues related to environmental pollution • Due to energy production • Due to the use of CFC’s and HCFC’s • Matches demand with source availability • Crucial for improving life standards in developing countries

  5. 1. Thermodynamic basis www.sara-project.net

  6. Underlying Physics Thermodynamics Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 1st Law: The change of internal energy (U) of a system is equal to the heat absorbed (Q), plus the external work (W) done on the system W, Q related to the changes the system experiences when going from an initial to a final state

  7. T T F F I V I V p p Thermodynamic Cycle Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Cyclical Transformation or Cycle Simple Transformation

  8. Entropy Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 The concept of entropy was originally introduced in 1865 by Rudolf Clausius. He defined the change in entropy of a thermodynamic system, during a reversible process in which an amount of heat ΔQ is applied at constant absolute temperature T, as ΔS = ΔQ / T Clausius gave the quantity S the name "entropy", from the Greek word τρoπή, "transformation". Since this definition involves only differences in entropy, the entropy itself is only defined up to an arbitrary additive constant

  9. Thermodynamics - 2nd Law Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 The most probable processes that can occur in an isolated system are those in which entropy increases or remains constant In other words: In an isolated system there is a well-defined trend of occurrence of process and this is determined by the direction in which entropy increases. In other words: Heat flows naturally from a system of higher temperature to a system of lower temperature.

  10. Ideal Carnot Refrigeration Cycle Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 12 Isothermal expansion 23 Adiabatic compression 34 Isothermal compression 41 Adiabatic expansion

  11. Useful cooling energy COP = Net energy supplied by external sources Coefficient of Performance (COP) Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  12. Coefficient of Performance (COP) (2) Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 • COP of the refrigeration sub-system • Thermal-driven system • Electricity-driven system

  13. SystemPerformance Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 STR (System Thermal Ratio) : SEE (System electrical efficiency) : System efficiency :

  14. 2. Conventional cooling cycle www.sara-project.net

  15. Conventional cooling cycle Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  16. Compression Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Vapor is compressed and its temperature increases

  17. Condensation Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 The fluid at "high pressure" is cooled by ambient air and therefore condensed

  18. Expansion Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 The liquid refrigerant is depressurized and its temperature decreases

  19. Evaporation Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 The liquid refrigerant at "low pressure" receives heat at low temperature and evaporates

  20. 3.Thermal Solar Cooling Techniques www.sara-project.net

  21. Thermal Solar Cooling Techniques Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Absorption Cooling Energy is transferred through phase-change processes Adsorption Cooling Energy is transferred through phase-change processes Desiccant Cooling Energy is transferred through latent heat processes The cooling capacity is based on the physical properties of the cooling fluid, that will change phases at different temperatures, depending on its pressure.

  22. 3.Thermal Solar Cooling Techniques 3.1 ABSORTION COOLING www.sara-project.net

  23. Absorption Cooling Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Substances used

  24. NH3 systems • Improved reliability, at low cost, independent control of the cooling medium • Improved pump reliability at low cost • Improved reliability of the fluid level sensors • Increased performance of the various heat transfer processes in the machine • Simplified system concepts Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  25. Properties of H2O – NH3 Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  26. LiBr systems Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 • Increased performance and reduction of cost of solar collectors • Increased performance and reduction of cost of storage systems (e.g. thermochemical) Development of low capacity absorption machines • Development of low capacity air-cooled absorption machines • Increased performance of the various heat transfer processes in the machine

  27. Properties of LiBr – H2O Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  28. Real application – Solar collectors Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Source: K. Sumathy, Z. C. Huang and Z. F. Li, Solar Energy, 2002, 72(2), 155-165

  29. Absorption machine Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Source: K. Sumathy, Z. C. Huang and Z. F. Li, Solar Energy, 2002, 72(2), 155-165

  30. Single effect Yazaki machine (10 ton LiBr) Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  31. System combined to sub-floor exchanger Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  32. 3.Thermal Solar Cooling Techniques 3.2 ADSORTION COOLING www.sara-project.net

  33. Adsorption cooling Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Adsorption is the use of solids for removing substances from gases and liquids The phenomenon is based on the preferential partitioning of substances from the gaseous or liquid phase onto the surface of a solid substrate. The process is reversible

  34. Adsorption Phase 1 Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Heating and pressurization The adsorbent temperature increases, which induces a pressure increase, from the evaporation pressure up to the condensation pressure. This period is equivalent to the "compression" phase in compression cycles.

  35. Adsorption Phase 2 Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Heating and desorption + condendsation During this period, the adsorber continues receiving heat while being connected to the condenser, which now superimposes its pressure. The adsorbent temperature continues increasing, which induces desorption of vapour. This desorbed vapour is liquified in the condenser. The condensation heat is released to the second heat sink at intermediate temperature. This period is equivalent to the "condensation" in compression cycles.

  36. Adsorption Phase 3 Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Cooling and depressurization During this period, the adsorber releases heat while being closed. The adsorbent temperature decreases, which induces the pressure decrease from the condensation pressure down to the evaporation pressure. This period is equivalent to the "expansion" in compression cycles.

  37. Adsorption Phase 4 Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Cooling and adsorption + evaporation During this period, the adsorber continues releasing heat while being connected to the evaporator, which now superimposes its pressure. The adsorbent temperature continues decreasing, which induces adsorption of vapor. This adsorbed vapour is evaporated in the evaporator. The evaporation heat is supplied by the heat source at low temperature. This period is equivalent to the "evaporation" in compression cycles.

  38. Adsorption Cooling - Summary Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 The cycle is intermittent because production of cooling energy is not continuous: it occurs only during part of the cycleWhen there are two adsorbers in the unit, they can be operated separately and production of cooling energy can be quasi-continuous. When all the energy required for heating the adsorber(s) is supplied by the heat source, the cycle is termed single effect. Typically, for domestic refrigeration conditions, the COP of single effect adsorption cycles is of about 0.3-0.4. When there are two adsorbers or more, other types of cycles can be designed. In double effect cycles or in cycles with heat regeneration, some heat is internally recovered between the adsorbers, and that improves the COP.

  39. Adsorption cooling - Examples Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  40. 3.Thermal Solar Cooling Techniques 3.3 DESICCANT REFRIGERATION www.sara-project.net

  41. Desiccant refrigeration Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Addresses the issue of thermal comfort by modifying the water vapor content in a space.

  42. Desiccant refrigeration principle Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  43. Desiccant refrigeration flow-chart Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  44. 4. Using Solar Energy in the Cooling Cycle www.sara-project.net

  45. Working fluids Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 Solar collector sub-cycle Refrigeration sub-cycle

  46. Basic Refrigeration Cycle Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118

  47. Heat-driven systems (1) Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 • Absorption

  48. Heat-driven systems (2) Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 • Adsorption

  49. Heat-driven systems (3) Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 • Chemical reaction

  50. Heat-driven systems (4) Sustainable Architecture Applied to Replicable Public Access Buildings www.sara-project.net Contract:TREN/04/FP6EN/S07.31838/503118 • Desiccant system