A magnetic refrigeration apparatus according to the present disclosure includes a magnetic-field source and two or more bed rings. The bed rings can be arranged in pairs with shared cold and hot fluid plenums. A flow of heat transfer fluid may pass at least partially radially through the shared fluid plenum or through a connection between the fluid plenum and one or more flow tubes. The MR apparatus and systems of the present disclosure may further include one or more circumferential flux returns with radial through-hole passageways to accommodate flow tubing. For apparatus configurations with an even number of bed rings, the axial dimension of the passageways may be smaller than the circumferential dimension of the passageways.

Systems and methods disclosed herein relate to a cryogenic refrigeration system which may use a compression based cryocooler or liquid nitrogen pre-cool to cool a medium to ˜80K, and may in conjunction with a magnetic refrigeration system operating in the sub-80K temperature regime to provide cooling to a medium to temperatures below 80K. In some embodiments, the disclosed system may be useful for cooling on the order of about 3 kg/day to about 300 kg/day of hydrogen gas to liquid form, with higher efficiency than a standard vapor compression based system. This higher efficiency may make the system a more attractive candidate for use in cryogenic cooling applications.

Integral linear cryogenic Stirling refrigerator comprised of the free piston positive displacement pressure wave generator, the moving assembly of which is connected to the free piston displacer by the dynamic “spring-mass-spring” mechanical phase shifter the mechanical properties of which (spring rates and weight) are selected to provide a predetermined phase lag of motion of the displacer piston relative to the moving assembly of pressure wave generator.

A magnetic refrigeration system includes a plurality of heat transporters, a magnetic field application unit, and a drive mechanism. Each heat transporter is switched between a heat generating and heat absorbing states in response to magnetic field application and cancellation of the magnetic field application. The heat transporters are arranged between low and high temperature side heat exchangers. The magnetic field application unit applies a magnetic field to the heat transporters so that a heat transporter to which a magnetic field is applied and a heat transporter to which a magnetic field is not applied are alternately arranged. The drive mechanism periodically moves at least the plurality of heat transporters so that a heat transporter to which the magnetic field is applied is periodically switched and so that a state of thermal contact is periodically switched. An end portion of at least one heat transporter is a heat transfer accelerator.

A magneto-caloric thermal diode assembly includes a magneto-caloric cylinder. A plurality of thermal stages is stacked along an axial direction between a cold side and a hot side. A hot side heat exchanger is positioned at the hot side of the plurality of thermal stages. The hot side heat exchanger includes a plurality of pins or plates for rejecting heat to ambient air about the hot side heat exchanger. A cold side heat exchanger is positioned at the cold side of the plurality of thermal stages. A heat transfer fluid is flowable through the cold side heat exchanger. The cold side heat exchanger is configured such that the heat transfer fluid rejects heat to the cold side of the plurality of thermal stages when the heat transfer fluid flows through the cold side heat exchanger.

A magnetic refrigeration apparatus includes one or more beds of magnetocaloric material arranged along a circumferential direction. The apparatus also includes a heat transfer fluid, one or more hot side heat exchangers (HHEX), one or more pumps or fluid displacement devices configured to move the heat transfer fluid, and a magnetic-field source. The magnetic-field source generates magnetic flux oriented substantially in a radial direction through the beds. The field source advantageously includes one or more pole pieces, one or more axial-end magnets, and one or more axial-end flux return pieces. Additionally, one or more circumferential flux returns, one or more gap flux return pieces, one or more side magnets, and one or more side flux return pieces can be added to increase system performance and reduce cost.

A fluid temperature control device includes a magnetic circuit portion and a coil waterproof structure. The magnetic circuit portion includes a magnetic working substance container containing a magnetic working substance, and a coil that applies a magnetic field to the magnetic working substance container. The magnetic working substance container allows a fluid to flow through it to exchange heat with the magnetic working substance. The coil waterproof structure hinders water generated in the magnetic working substance container from flowing to the coil.

A heat pump, as provided herein, may include a hot side heat exchanger, a cold side heat exchanger, a pump, and a caloric heat pump. The caloric heat pump may include a regenerator housing, a plurality of stages, and a field generator. The regenerator housing may extend along an axial direction between a first end portion of the regenerator housing and a second end portion of the regenerator housing. The plurality of stages may be arranged sequentially along the axial direction from the first end portion to the second end portion. The plurality of stages may be arranged so that caloric temperature peaks of the plurality of stages increase along the axial direction according to a predetermined, non-linear curve. The field generator may be positioned adjacent to the plurality of stages to subject the plurality of stages to a variable field generated by the field generator.

A heat pump system includes a magneto-caloric material disposed within a chamber of a regenerator housing. A back iron extends between an outer magnet and an inner magnet in order to provide a flux path between the outer and inner magnets. At least a portion of the back iron extends between the outer and inner magnets along the radial direction and is not positioned coplanar with the inner and outer magnets in a plane that is perpendicular to the axial direction. A related refrigerator appliance is also provided.

A magneto-caloric thermal diode assembly includes a first magneto-caloric cylinder and a second magneto-caloric cylinder. The second magneto-caloric cylinder and a second plurality of thermal stages are nested concentrically within the first magneto-caloric cylinder and a first plurality of thermal stages. A plurality of magnets is distributed along a circumferential direction within a non-magnetic ring in each thermal stage of the first and second pluralities of thermal stages. Each thermal stage of the first and second pluralities of thermal stages has a first half and a second half. A polarity of the magnets of the plurality of magnets within the first half is oriented opposite a polarity of the magnets of the plurality of magnets within the second half along the radial direction in each thermal stage of the first and second pluralities of thermal stages.