| 摘要 |
The disclosed system produces liquid nitrogen from ambient air which is supplied under pressure to a membrane separator. Most of the gases other than nitrogen permeate the membranes, and are vented to the atmosphere leaving almost pure nitrogen gas. The nitrogen gas is then supplied to a Dewar container in the neck of which is mounted the cylindrical cold head of a miniature cryogenic refrigerator. The temperature of the cold head is maintained below the liquefaction temperature of the nitrogen so that the gas is liquified as it passes over the cold head in heat exchanging relationship.
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