Cryogenic+Refrigeration.ppt

文档介绍：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. <
Cryocoolers
Types:
Joule-Thomson
Brayton
Stirling
Pulse Tube
Gifford-McMahon
Applications-MRI
Metals and plastics-stronger, durable, elec. resis. dec. (e close to superconductors)
Metal wire coiled to produce mag. field w/ no heat or consumption of elec. power, and remains cold
Applications
Common Extensible Cryogenic Engine
ps super-cooled to similar low temps w/ liquid O2 and H2 mixture.
As CECE burns its frigid fuels, posed of hot steam is produced and propelled out the nozzle creating thrust.
The steam is cooled