An active gas regenerative refrigerator includes a plurality of compressor-expander units, each having a hermetic cylinder with a drive piston configured to be driven reciprocally therein, and a quantity of working fluid in each end of the cylinder. A piston seal in a central portion of the cylinder prevents passage of the working fluid between ends of the cylinder. Movement of the piston to a first extreme results in radial compression of one of the quantities of working fluid in a cylindrical gap formed between one end of the piston and an inner surface of the cylinder, while the other quantity is expanded in the opposite end of the cylinder. The piston includes a plurality of magnets arranged in pairs, with magnets of each pair positioned with like-poles facing each other. A piston drive is configured to couple with transverse magnetic flux regions formed by the magnets.

The invention relates to a method for cooling, purifying and separating a gaseous mixture containing at least one impurity, in which the gaseous mixture is cooled to a temperature no higher than the temperature at which the at least one impurity solidifies in a heat exchanger having cooling passages, the cooling passages being at least partially covered with a coating and/or physically treated and/or chemically treated, the coating and/or the treatment serving to limit or even prevent the solidified impurity from forming and/or adhering to a surface of the passages; at least one portion of the solidified impurity exiting the cooling passages of the heat exchanger is collected; and the gaseous mixture is withdrawn from the heat exchanger.

A method for controlling an oxygen liquefaction device includes measuring a flow rate from an oxygen concentration subsystem to a liquefaction subsystem, comparing the flow rate to a flow rate setpoint, and adjusting a cycle timing of the oxygen concentration subsystem in accordance with the comparing. A device for producing liquid oxygen, includes an oxygen concentrator, a liquefaction system, that receives oxygen enriched gas from the concentrator, and condenses it to produce a liquid product. The device further includes a liquid product storage tank, a sensor, that measures a flow rate from the oxygen concentrator to the liquefaction system and a controller that adjusts an oxygen concentrating cycle time in response to the measured flow rate.

A system that includes: (a) a liquid natural gas storage tank fluidly coupled to a first compressor, (b) a fuel cell having an inlet fluidly coupled to the first compressor and an H.sub.2 gas outlet fluidly coupled to a heat exchanger, wherein the heat exchanger receives compressed liquid natural gas from the first compressor; (c) an active magnetic regenerative refrigerator H.sub.2 liquefier that comprises at least one layer of a magnetic refrigerant material, wherein the active magnetic regenerative refrigerator H.sub.2 liquefier receives cooled H.sub.2 gas from the heat exchanger.

A method for separating a gas mixture at subambient temperature, in which a gas mixture is sent to a heat-insulated chamber, cooled and separated in a column, and placed inside the chamber so as to produce at least two fluids, each of which is enriched with a component from the gas mixture. At least one fluid from the method can be heated inside the chamber or vaporized via heat exchange with at least one heating member including at least one element having magnetocaloric properties and built into a circuit configured to conduct a magnetic flux. The element is alternatingly in thermal contact with a cold source, made up of the fluid to be heated, and a hot source, made up of a source hotter than the fluid to be heated, and variation in the magnetic flux via the magnetocaloric effect generates electrical and/or mechanical energy.

The present invention relates to a cryocooler suitable for gas liquefaction applications, that comprises a coldhead with one or more refrigeration stages; further comprising: a refrigerator compressor for distributing compressed gas-phase cryogen inside the coldhead; a heat exchanging coil arranged at least partially around the external region of the coldhead; at least one extraction orifice communicating a gas circulation circuit inside the coldhead with the heat exchanging coil; acting said extraction orifice/s as pass-through port/s which allow the gas inside the coldhead to flow through the inside of the heat exchanger coil for exchanging heat with the exterior thereof, and wherein the heat exchanging coil is adapted to connect and redirect the gas to one return port connected to the gas circulation circuit. Another object of the invention relates to a cryogen-gas liquefaction system and a method for liquefaction of gases that comprises said system.

A dewar includes two coaxial openings of different sizes (e.g., to allow for interfacing with a Stirling cryocooler and a Stirling generator), a polytetrafluoroethylene or glass inner chamber (e.g., to reduce conductive heat transfer, particularly through the dewar neck), and an integrated, annular desiccant ring (e.g., for drying low-pressure, ambient air).