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Cryogenic Engineering CERN, March 8 - 12, 2004

Cryogenic Engineering CERN, March 8 - 12, 2004. Temperature reduction by throttling and mixing Temperature reduction by work extraction Refrigeration cycles: Efficiency, compressors, helium, hydrogen Cooling of devices. cold. cold. Process running by itself. Process needing driving power.

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Cryogenic Engineering CERN, March 8 - 12, 2004

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  1. Cryogenic EngineeringCERN, March 8 - 12, 2004 • Temperature reduction by throttling and mixing • Temperature reduction by work extraction • Refrigeration cycles: Efficiency, compressors, helium, hydrogen • Cooling of devices Cryogenic Engineering, CERN, March 2004

  2. cold cold Process running by itself Process needing driving power Mankind had an intellectual difficulty with the production of refrigeration: We could not learn it from nature. The problem: One has to add energy to remove energy. Cryogenic Engineering, CERN, March 2004

  3. cold cold Where should the outside power be applied Solution: One needs an additional sytem: The refrigerator Cryogenic Engineering, CERN, March 2004

  4. Refrigeration cyle Flow Diagram • Refrigerant • Method to increase pressure • Method to reduce entropy • Method to reduce the temperature • Method to transfer the refrigeration • Recuperation T-s Diagramm Cryogenic Engineering, CERN, March 2004

  5. isentropic T T Ideal Real adiabatic B A B A Tw Tw Work Work Tc Tc D C C D Cooling power S S DS1 DS2 Widen the low-temperature end of the cycle as shown in the T-S diagram Cryogenic Engineering, CERN, March 2004

  6. Compressor and Aftercooler • Purpose: Increase the pressure and reduce entropy • Types of compressors • Volumetric compressors: piston, screw • Turbocompressors Cryogenic Engineering, CERN, March 2004

  7. Piston compressor Oilfree labyrinth piston compressors. Preferred by CERN until about 1980. Cryogenic Engineering, CERN, March 2004

  8. Screw Compressor Oil flooded screw compressor preferred at CERN since about 1985. Cryogenic Engineering, CERN, March 2004

  9. Screw compressor principle Cryogenic Engineering, CERN, March 2004

  10. Cryogenic Engineering, CERN, March 2004

  11. Screw Compressor Installation Cryogenic Engineering, CERN, March 2004

  12. Cryogenic Engineering, CERN, March 2004

  13. Cryogenic Engineering, CERN, March 2004

  14. Cryogenic Engineering, CERN, March 2004

  15. Cryogenic Engineering, CERN, March 2004

  16. Cold Compressor Cartridges of 2.4 kW @ 1.8 K Refrigeration Units Cold compressor impeller IHI-Linde 1st stage The four-stage LHC cold compressors Cryogenic Engineering, CERN, March 2004

  17. Isentropic Efficiency of Cold Compressors Cryogenic Engineering, CERN, March 2004

  18. Flow Compliance of “Mixed” Compression Flow (variable) P out (fixed) P inter Stall line Volumetric N3 Volumetric N2 Choke line N1 P inter Hydrodynamic P in (fixed) Flow For fixed overall inlet & outlet conditions, coupling of the two machines via P inter maintains the operating point in the allowed range Cryogenic Engineering, CERN, March 2004

  19. How to evaluate efficiency and to identify losses • When discussing expanders, we shortly talked about reversibility • In power engineering there is always a best method to do something, i. e. no unnecessary losses = reversibility • Losses can be idebtified by the deviation from reversibility • Comparison is the input power • We have to give refrigeration a value in the scale of the input power • Carnot ratio Cryogenic Engineering, CERN, March 2004

  20. The definition of exergy • Minimum amount of work to produce refrigeration • Exergy= Mimimum Power= Q*(Ta-T0)/T0 • Minimum amount of power to change the state of a fluid from an initial state 1 to a final state 2: • e2-e1 = h2-h1 + Ta*(s2-s1) Cryogenic Engineering, CERN, March 2004

  21. Cycle for liquefaction of hydrogen The Exergy Mountains Minimum Power to obtain Heating or Cooling (W/W) Prometheus (prehistoric) Cryogenic Engineering, CERN, March 2004

  22. Specific exergy of cold copper and helium Cryogenic Engineering, CERN, March 2004

  23. Stored exergy in the cooled-down LHC Cryogenic Engineering, CERN, March 2004

  24. Helium is recovered from natural gas Cryogenic Engineering, CERN, March 2004

  25. Cryogenic Engineering, CERN, March 2004

  26. Cryogenic Engineering, CERN, March 2004

  27. Development of the size of helium refrige- rators and liquefiers in the last century. Cryogenic Engineering, CERN, March 2004

  28. C.O.P. of Large Cryogenic Helium Refrigerators Cryogenic Engineering, CERN, March 2004

  29. Cryogenic Engineering, CERN, March 2004

  30. Cryogenic Engineering, CERN, March 2004

  31. Cryogenic Engineering, CERN, March 2004

  32. History of gas liquefaction Cryogenic Engineering, CERN, March 2004

  33. History of use of liquid hydrogen Commercial Supply Heavy Water Rockets Hydrogen Bomb Bubble Chambers Cold Neutron Source Cryogenic Engineering, CERN, March 2004

  34. Cryogenic Engineering, CERN, March 2004

  35. Cryogenic Engineering, CERN, March 2004

  36. Liquid Hydrogen FuelledRocket Cryogenic Engineering, CERN, March 2004

  37. BEBC (Big European Bubble Chamber at CERN) Cryogenic Engineering, CERN, March 2004

  38. Liquid Hydrogen Fuelled Car Cryogenic Engineering, CERN, March 2004

  39. Cryogenic Engineering, CERN, March 2004

  40. Liquid hydrogen tank in car Cryogenic Engineering, CERN, March 2004

  41. Hydrogen Cryogenic Engineering, CERN, March 2004

  42. Future Large Scale Hydrogen Liquefier Expected Efficiency: 60 % of Carnot 7 kWh/kg LH2 Cryogenic Engineering, CERN, March 2004

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