| 摘要 |
Life support is provided by a cryogenic closed circuit system for either hyperbaric, isobaric or hypobaric respiratory environments. Oxygen content in a gas mixture is maintained in a selected partial pressure range by establishing thermodynamic equilibrium between a liquid oxygen supply, which is maintained at an appropriate temperature, and a gas mixture within an enclosed volume communicating with the liquid oxygen. Incoming gases are passed into the gas-containing volume and adjusted to an appropriate partial pressure of oxygen solely by virtue of saturation equilibrium, and independently of ambient pressure and gas mixture variations. The useful life of a given oxygen supply volume is greatly extended because of the high compaction ratio of liquid oxygen with respect to oxygen gas at standard temperature and pressure, and because of full physiological use of the oxygen. The temperature of the liquid oxygen may be controlled through the use of a cryogenic reservoir, a cryogenic refrigerator or other means. A heat exchanger may be deployed in the closed circuit system to cool incoming contaminated gases to cryogenic levels and to heat outgoing breathable gases to acceptable levels, and to provide more efficient use of the cryogen. The closed circuit system may further include means for compensating for ambient pressure variations by the injection of an inert gas or gases and for cleansing of incoming gases by removal of water vapor and carbon dioxide. |
