Forced Two-Phase Helium Cooling of Large Superconducting Magnets
A major problem with all large superconducting magnets is the cryogenic and refrigeration system. Almost all of the large magnets are cryogenically stabilized. They are cooled in a bath of boiling helium. Nucleate boiling in liquid helium permits heat fluxes of 3000 W/m2 to be transferred with a temperature drop of less than 0.5 K. The bath-cooled magnet is difficult to cool from room temperature to 4 K. Helium, which is a difficult fluid to use as a coolant because of its low atomic weight, must flow into each region of the magnet; if the flow in a section of the magnet is restricted, stratification occurs and that magnet section remains warm.
KeywordsPressure Drop Heat Exchanger Liquid Helium Cooling Circuit Volumetric Efficiency
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