Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method includes identifying at least partial degradation of a magnetocaloric material in a magnetic cooling system, wherein the magnetiocaloric material has a Curie temperature. The method also includes regenerating the magnetocaloric material by maintaining the magnetocaloric material at a regenerating temperature, wherein the regenerating temperature is different from the Curie temperature of the magnetocaloric material.

Abstract: A permanent magnet assembly is disclosed that is adapted to provide a magnetic field across an arc-shaped gap. Such a permanent magnet assembly can be used, for example, to provide a time-varying magnetic field to an annular region for use in a magnetic refrigerator.

Abstract: A slush hydrogen production device (10) utilizes a hydrogen slushifier magnetic refrigerator (30) having a wheel (50) of material exhibiting the magnetocaloric effect. The wheel is rotated through a magnetic field of varying intensity around the circumference of a wheel housing (36) created by the windings of superconductive magnets (56). The material of the wheel (50) follows a magnetic Carnot cycle as the wheel rotates (36) through regions of low temperature heat transfer and high temperature heat transfer. Liquid hydrogen is supplied to the regions of low and high temperature heat transfer through inlet pipes (39 and 42). Gaseous hydrogen is produced in the high temperature heat transfer region and vented away by an outlet pipe (48). Solid hydrogen is produced in the low temperature heat transfer region by direct solidification upon the magnetic wheel (50); and is removed by scrapers (76) and deposited in a compartment (26) where it mixes with liquid hydrogen to form slush hydrogen.

Abstract: A magnetic refrigeration apparatus has an annular container including a plurality of magnetic regenerator compartments containing magnetocaloric material, and a magnet mounted for rotation around the annular container, whereby the motion of the magnet produces a variation of magnetic field strength in the magnetic regenerator compartments, which in term leads to a variation in temperature of the magnetocaloric material in the magnetic regenerator compartments. Heat transfer fluid is propelled by a pump, and directed to and from the regenerator compartments and hot and cold heat exchangers by valves. Each valve includes an axial port and a plurality of radial ports.

Abstract: A magnetic refrigeration apparatus has an annular container including a plurality of magnetic regenerator compartments containing magnetocaloric material, and a magnet mounted for rotation around the annular container, whereby the motion of the magnet produces a variation of magnetic field strength in the magnetic regenerator compartments, which in term leads to a variation in temperature of the magnetocaloric material in the magnetic regenerator compartments. Heat transfer fluid is propelled by a pump, and directed to and from the regenerator compartments and hot and cold heat exchangers by valves. Each valve includes an axial port and a plurality of radial ports.

Abstract: A rotating magnetic refrigeration apparatus has magnetic regenerator beds arranged in a ring that is mounted for rotation about a central axis, such that each bed moves into and out of a magnetic field provided by a magnet as the ring rotates. Heat transfer fluid is directed to and from the regenerator beds by a distribution valve which is connected by conduits to the hot and cold ends of the beds and which rotates with the ring of beds. The distribution valve has a stationary valve member which is connected by conduits to a hot heat exchanger and to a cold heat exchanger. The beds include magnetocaloric material that is porous and that allows heat transfer fluid to flow therethrough.

Abstract: A rotating magnetic refrigeration apparatus has magnetic regenerator beds arranged in a ring that is mounted for rotation about a central axis, such that each bed moves into and out of a magnetic field provided by a magnet as the ring rotates. Heat transfer fluid is directed to and from the regenerator beds by a distribution valve which is connected by conduits to the hot and cold ends of the beds and which rotates with the ring of beds. The distribution valve has a stationary valve member which is connected by conduits to a hot heat exchanger and to a cold heat exchanger. The beds include magnetocaloric material that is porous and that allows heat transfer fluid to flow therethrough.

Abstract: An active magnetic regenerator refrigeration apparatus includes one or more reciprocating regenerator beds and a heat transfer fluid distribution valve that is activated as the bed is moved between a position in which it is in the magnetic field of a magnet to a position in which it is outside the magnetic field of the magnet. The distribution valve has a first valve member and a moving second valve member slidingly engaged to each other, each of which has ports by which heat transfer fluid may be provided to and received from the valve member. The bed is mounted to the moving second valve member so that heat transfer fluid is conveyed to and through the valve in a single direction into the regenerator bed. The material of the bed exhibits the magnetocaloric effect and the temperature of the bed rises when it enters the magnetic field of the magnet and decreases when it exits the magnetic field, providing a refrigeration cycle.

Abstract: In an active magnetic regenerator apparatus having a regenerator bed of material exhibiting the magnetocaloric effect, flow of heat transfer fluid through the bed is unbalanced, so that more fluid flows through the bed from the hot side of the bed to the cold side than from the cold side to the hot side. The excess heat transfer fluid is diverted back to the hot side of the bed. The diverted fluid may be passed through a heat exchanger to draw heat from a fluid to be cooled. The apparatus may be operated at cryogenic temperatures, and the heat transfer fluid may be helium gas and the fluid to be cooled may be hydrogen gas, which is liquified by the device. The apparatus can be formed in multiple stages to allow a greater span of cooling temperatures than a single stage, and each stage may be comprised of two bed parts.

Abstract: A magnetic refrigerator has a rotating magnetic wheel which includes a stack of spaced rings of magnetic material. Heat transfer plates of a high temperature heat extractor are interleaved with the magnetic rings and extend to a solid heat transfer conduit which leads to a high temperature terminal. Superconducting magnet coils are mounted to provide a magnetic field through the magnetic wheel at the position of the high temperature heat transfer plates. Low temperature extractor heat transfer plates are positioned outside of the magnetic field and interleave with the rings of the magnetic wheel to transfer heat thereto which is conducted from a low temperature terminal through a solid conduit.