LIQUEFYING AND STORING A GAS

摘要

Apparatus and methods for improving the safety and efficiency and decreasing the cost of producing liquid oxygen with a small-scale use liquefaction device, according to various embodiments of the present invention. In one embodiment, a switch (666) is electrically coupled to a storage dewar pressurizing means (646), the switch (666) positioned to be activated by a portable dewar (668) upon engagement of portable dewar (668) with storage dewar (620). Cryocooler (602) and/or cooling fan (3203, 3208) enter low power mode when dewar (120) liquid level reaches a predetermined level, and return to a full power mode when dewar (120) liquid level drops to another predetermined level. A cold finger (408) of the cryocooler (102) extends within the dewar (420) and may prevent overfilling of the dewar (420). The cold finger (408) has a temperature gradient. As the gas liquefies and fills the dewar (420), the liquid level rises only to a level (417) on the cold finger (408) at which the temperature exceeds the boiling point of oxygen.