A module for warming and, alternately, for cooling, this module comprising an electrocaloric capacitor, an electrical energy storage device and a controllable circuit for transferring electrical energy between the electrocaloric capacitor and the energy storage device. The controllable circuit comprising an inductor connected between the electrocaloric capacitor and the storage device and at least one controllable switch. There is further included a unit programmed to control the switch so as to cause the transfer circuit to toggle successively into the following states and in the following order: an energy recovery state, a disabled state in which it electrically isolates the electrocaloric capacitor and the energy storage device, an energy release state and the disabled state, and each time to maintain the transfer circuit in the disabled state for a duration greater than a predetermined threshold.

A module for warming and, alternately, for cooling, this module comprising an electrocaloric capacitor, an electrical energy storage device and a controllable circuit for transferring electrical energy between the electrocaloric capacitor and the energy storage device. The controllable circuit comprising an inductor connected between the electrocaloric capacitor and the storage device and at least one controllable switch. There is further included a unit programmed to control the switch so as to cause the transfer circuit to toggle successively into the following states and in the following order: an energy recovery state, a disabled state in which it electrically isolates the electrocaloric capacitor and the energy storage device, an energy release state and the disabled state, and each time to maintain the transfer circuit in the disabled state for a duration greater than a predetermined threshold.

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%.

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.

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 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 magnetic cooling apparatus having a plurality of cooling modules, where each of the cooling modules includes at least one magnetic regenerator allowing a heat transfer fluid to pass therethrough and filled with a magnetocaloric material; and a fluid supply device to supply the heat transfer fluid into the magnetic regenerator. The cooling modules are rotatably arranged in a circumferential direction.

A magnetic cooling apparatus having a plurality of cooling modules, where each of the cooling modules includes at least one magnetic regenerator allowing a heat transfer fluid to pass therethrough and filled with a magnetocaloric material; and a fluid supply device to supply the heat transfer fluid into the magnetic regenerator. The cooling modules are rotatably arranged in a circumferential direction.