Cryogenics

Cryogenics, Cryogenic ( from Ancient Greek κρύος [ kryos ] " frost, ice " ) or low-temperature technique is the technique for producing low temperatures ( Joule- Thomson effect ) and the use of physical effects at low temperatures ( liquefaction and separation of gases ). The cryogenics covers the temperature range below about -150 ° C. Technically easily accessible temperatures of 77.4 K ( -195.8 ° C), the boiling point of nitrogen, 20.4 K ( with hydrogen) and 4.2 K ( with helium). Lower temperatures can be reached by reducing the pressure and the consequent change in the boiling points. With helium to get so down to about 1 K, with the (expensive) isotope 3He even up to 1 mK. Wide application is liquid helium in the cooling of superconducting coils of electromagnets.

Applications of cryogenics

  • Power engineering (nuclear fusion reactors)
  • High-energy physics (particle accelerators )
  • Vacuum Technology ( cryopump )
  • Energy Systems ( SMES energy storage, liquid hydrogen fuel)
  • Rocket technology ( for example, pumps for liquid oxygen )
  • Metrology ( SQUIDs, detectors, NMR)
  • Cryobiology (English Cryobiology )
  • Process Engineering ( liquefaction of gases, cryogenic rectification, recycling)
  • Manufacture of industrial gases
  • Petrochemical industry, natural gas industry ( LNG )
  • Food industry ( shock freezing )
  • Energy recovery technology
  • Electrical, Electronic
  • Medicine: MRI, cryosurgery, extraction of medical gases
  • Burials, Promession
  • Preservation, cryopreservation
  • Cryonics or Kryostase

Risks of cryogenic gases

  • Suffocation and frostbite ( freezer burn )
  • Pressure increase due to evaporation
  • Fire hazard due to oxygen enrichment
  • Thermal expansion
  • Material embrittlement

Storage and transport

Liquid nitrogen or liquid helium can be conveniently stored and transported in Dewar vessels for cooling purposes. For safe loading and refilling quick couplings are used.

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