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