Cryogenic Refrigeration Cryogenic Refrigeration
Maha Hosain
Background Info
• Cryogenics – science of production and effects of very low temperatures
• Limit to lowest temp—absolute zero (0K)• Cryogenic region below 120K (-153ºC)• Cryogenic Liquids super-freezing permanent
gases to liquid states, ex: oxygen, nitrogen, hydrogen, and helium– Liquid Nitrogen: most easily available– Liquid Helium: lowest temp. <2.17K
Cryocoolers
Types:
•Joule-Thomson
• Brayton
• Stirling
• Pulse Tube
• Gifford-McMahon
Applications-MRI
• Metals and plastics-stronger, durable, elec. resis. dec. (become close to superconductors)
• Metal wire coiled to produce mag. field w/ no heat or consumption of elec. power, and remains cold
ApplicationsCommon Extensible Cryogenic Engine
Engine comps super-cooled to similar low temps w/ liquid O2 and H2 mixture.
As CECE burns its frigid fuels, gas composed of hot steam is produced and propelled out the nozzle creating thrust.
The steam is cooled by the cold engine nozzle, condensing and eventually freezing at the nozzle exit to form icicles.
Hydrogen light =>take larger spacecrafts to moon
Cryonics• Freezing body• Not acceptable app.
of cryogenics
Cryosurgery• freezing of portions
of the body• destroy unwanted or
malfunctioning tissue
References
• www.kirtland.af.mil/art/index.asp?galleryID=3978
• http://cryogenics.nist.gov/
• http://www.youtube.com/watch?v=Pnf0gnfvvJA
• http://www.youtube.com/watch?v=1R7KsfosV