In order to provide a cascade heat pump with which a large temperature lift can be provided with high efficiency, a cascade heat pump comprising n stages where n≥2 is proposed. Each of the n stages has a heat pump with a coolant inlet, a first coolant outlet, and a second coolant outlet. Each heat pump has a hot side and a cold side and a flow divider to divide a coolant flow entering the coolant inlet between the hot side and the cold side. The first coolant outlet of the heat pump of each stage i, where i=1 . . . n−1, is connected to the coolant inlet of the heat pump of a subsequent stage i+1. The second coolant outlet of the heat pump of at least one subsequent stage i+1 is connected by a recirculation line to the coolant inlet of the heat pump of a preceding stage.

A cryostat system is kept at a cryogenic operating temperature without providing or supplying cryogenic fluids by a cryocooler. The cryostat system includes a superconducting magnet arrangement and a heat sink apparatus to prolong the time before the superconducting magnet arrangement quenches/returns to the normally conducting state if active cooling fails. The heat sink apparatus includes magnetocaloric material and is thermally connected to the superconducting magnet arrangement and/or to parts of the cryostat system through which ambient heat can flow to the superconducting magnet arrangement. In this way, the cryostat system can be operated in a truly “cryogen-free” manner while maintaining a sufficiently long time to quench in the event of potential operational malfunctions.

A dishwasher appliance includes a caloric heat pump system that is configured for heating and cooling a wash chamber of a tub. A field generator is positioned such that caloric material stages are moved in and out of a field of the field generator during operation of the caloric heat pump system. A pump circulates a heat transfer fluid between a first heat exchanger, a second heat exchanger and the caloric material stages.

A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

A heat pump system is provided that uses MCM to provide for heating or cooling. The heat pump can include one or more stages of MCM, each stage having an original peak Curie temperature. In the event the magneto caloric response of one or more stages of MCM degrades, the present invention provides for operating the heat pump system so that one or more stages of MCM are held at a different temperature from the original peak Curie temperature so as to restore the MCM to its original peak Curie temperature or to within a certain interval thereof. The present invention can be used with e.g., an appliance, air-conditioning systems (heating or cooling), or other devices using such a heat pump system as well.

A magnetic refrigeration material includes an alloy represented by a composition formula of La(Fe, Si).sub.13H, and the alloy includes α-Fe by a weight ratio lower than 1 wt % and a plurality of pores so that a packing fraction of the alloy is within a range from 85% to 99%.

In various aspects, methods of making perovskite manganese oxide particles are provided as well as perovskite manganese oxide particles made therefrom. The perovskite manganese oxide particles exhibit a strong magnetocaloric effect, making them well suited for applications in power generation and magnetic refrigeration, especially at or near room temperature. The methods can include forming an aqueous mixture of (i) a low-molecular-weight polymeric polyalcohol gel precursor, (ii) a stoichiometric amount of metal salts or hydrates thereof, wherein the metal salts or hydrates thereof comprise at least a Manganese (Mn), and (iii) a polybasic carboxylic acid; polymerizing the aqueous mixture to form a gel containing perovskite manganese oxide nanoparticles entrapped therein; and calcining the gel to remove at least a portion of organic material in the gel and form the perovskite manganese oxide particles. Method and systems are also provided for power generation and magnetic refrigeration using the perovskite manganese oxide particles.

A magnetocaloric regenerator unit comprising (A) at least one magnetocaloric material unit having a higher temperature hot side and a lower temperature cold side during operation, wherein the magnetocaloric material unit contains at least one magnetocaloric material, (B) at least one magnetic unit for producing a magnetic field over the magnetocaloric material contained in the magnetocaloric material unit, (C) at least one magnetic shielding comprising at least one window wherein the at least one magnetic shielding is mounted flexible to allow movement of the magnetic shielding between at least one first position and at least one second position thereby insulating the magnetocaloric material contained in the magnetocaloric material unit from the magnetic field when the magnetic shielding is in a first position and allowing the magnetic field to act on the magnetocaloric material through the at least one window when the magnetic shielding is in a second position.

A dual-mode magnetic refrigeration apparatus includes beds of magnetocaloric material, a magnet to apply a time-varying magnetic field to the beds, a heat transfer fluid (HTF), a pump to circulate the HTF, a hot side heat exchanger (HHEX), a cold side heat exchanger (CHEX), valves to direct flow of the HTF, and a controller configured to control periodic switching of the valves to allow the apparatus to operate in a first mode and in a second mode. The first mode transfers heat from the CHEX to the HHEX. In the second mode of operation, the periodic switching of the valves is suspended to allow unidirectional flow of the HTF through the HHEX, the beds, and the CHEX such that heat is transferred from the HHEX to the CHEX.

A process for liquefying a process gas comprising: introducing a heat transfer fluid into an active magnetic regenerative refrigerator apparatus that comprises (i) a high magnetic field section in which the heat transfer fluid flows from a cold side to a hot side through at least one magnetized bed of at least one magnetic refrigerant, (ii) a first no heat transfer fluid flow section in which the bed is demagnetized, (iii) a low magnetic or demagnetized field section in which the heat transfer fluid flows from a hot side to a cold side through the demagnetized bed, and (iv) a second no heat transfer fluid flow section in which the bed is magnetized; continuously diverting a bypass portion of the heat transfer fluid from the cold side of the low magnetic or demagnetized field section into a bypass flow heat exchanger at a first cold inlet temperature; and continuously introducing the process gas into the bypass flow heat exchanger at a first hot inlet temperature and discharging the process gas or liquid from the bypass flow heat exchanger at a first cold exit temperature; wherein the temperature difference between bypass heat transfer first cold inlet temperature and the process gas first cold exit temperature is 1 to 5 K.