System and method for reverse degradation of a magnetocaloric material

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.

1 . A method comprising:
 identifying at least partial degradation of a magnetocaloric material in a magnetic cooling system, wherein the magnetiocaloric material has a Curie temperature; and   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.   
     
     
         2 . The method of  claim 1 , wherein the regenerating temperature differs from the Curie temperature by at least five degrees Celcius. 
     
     
         3 . The method of  claim 1 , wherein the regenerating temperature differs from the Curie temperature by at least ten degrees Celcius. 
     
     
         4 . The method of  claim 1 , wherein the magnetocaloric material includes hydrogen, wherein the regenerating temperature is below a maximum temperature, and wherein the maximum temperature is a temperature at which at least a portion of the hydrogen will begin to leave the magnetocaloric material. 
     
     
         5 . The method of  claim 1 , wherein the magnetocaloric material comprises RE(TM x Si y ) 13 H z , where RE is a rare earth element and TM is a transition metal. 
     
     
         6 . The method of  claim 1 , further comprising suspending an active magnetic regenerator cycle of the magnetic cooling system while the magnetocaloric material is maintained at the regenerating temperature. 
     
     
         7 . The method of  claim 1 , further comprising:
 removing the magnetocaloric material from the magnetic cooling system such that the magnetocaloric material is maintained at the regenerating temperature remote from the magnetic cooling system; and   replacing the magnetocaloric material with a regenerated magnetocaloric material.   
     
     
         8 . The method of  claim 1 , wherein regenerating comprises reversing age splitting of the magnetocaloric material. 
     
     
         9 . A method comprising:
 forming at least one bed of a magnetic cooling system, wherein the at least one bed includes a magnetocaloric material, wherein the magnetocaloric material has a Curie temperature, and wherein a heat transfer fluid is configured to transfer heat to or from the magnetocaloric material in the at least one bed;   forming at least one valve of the magnetic cooling system to control a flow of the heat transfer fluid through the at least one bed and either a heater or a heat exchanger, wherein flow of the heat transfer fluid between the at least one bed and the heater regenerates the magnetocaloric material by maintaining the magnetocaloric material at a regenerating temperature, and wherein the regenerating temperature is different from the Curie temperature of the magnetocaloric material.   
     
     
         10 . The method of  claim 9 , wherein flow of the heat transfer fluid between the at least one bed and the heat exchanger cools the magnetocaloric material. 
     
     
         11 . The method of  claim 9 , wherein the at least one bed comprises a plurality of layers, wherein each layer of the at least one bed includes a distinct magnetocaloric material having a distinct Curie temperature, and wherein the distinct Curie temperature of the distinct magentocaloric material in a given layer is an average temperature of the given layer during an active magnetic regenerator cycle. 
     
     
         12 . An apparatus comprising:
 a heat transfer fluid;   a bed comprising a magnetocaloric material that has a Curie temperature, wherein the bed is configured to allow the heat transfer fluid to transfer heat to or from the magnetocaloric material; and   a heater configured to maintain the magnetocaloric material at a regenerating temperature for an amount of time to regenerate the magnetocaloric material, wherein the regenerating temperature is different from the Curie temperature of the magnetocaloric material.   
     
     
         13 . The apparatus of  claim 12 , wherein the heater is configured to heat the bed via the heat transfer fluid. 
     
     
         14 . The apparatus of  claim 12 , wherein the regenerating temperature is greater than the Curie temperature. 
     
     
         15 . The apparatus of  claim 12 , wherein the bed comprises a plurality of magnetocaloric materials having distinct Curie temperatures, and wherein the regenerating temperature is greater than a largest of the distinct Curie temperatures. 
     
     
         16 . The apparatus of  claim 12 , wherein the heater is remote from the bed, and wherein the bed is configured to be temporarily removed from the apparatus for regeneration by the heater. 
     
     
         17 . A heat transfer system comprising:
 a first subsystem comprising:
 a first heat transfer fluid; 
 a first bed having a first magnetocaloric material, wherein the first magnetocaloric material has a first Curie temperature; and 
 a first valve configured to control whether the first subsystem operates in regeneration mode or cooling mode; and 
   a second subsystem comprising:
 a second heat transfer fluid; 
 a second bed having a second magnetocaloric material, wherein the second magnetocaloric material has a second Curie temperature; and 
 a second valve configured to control whether the second subsystem operates in regeneration mode or cooling mode. 
   
     
     
         18 . The heat transfer system of  claim 17 , wherein:
 the first valve is configured to control the first subsystem to operate in the cooling mode and the second valve is configured to control the second subsystem to operate in the regenerating mode during a first period of time; and   the first valve is configured to control the first subsystem to operate in the regenerating mode and the second valve is configured to control the second subsystem to operate in the cooling mode during a second period of time.   
     
     
         19 . The heat transfer system of  claim 17 , wherein the first valve is configured to control the first subsystem to operate in the cooling mode and the second valve is configured to control the second subsystem to operate in the cooling mode during a given period of time. 
     
     
         20 . The heat transfer system of  claim 17 , wherein:
 the first bed comprises a first plurality of layers, wherein each layer of the first bed includes a distinct magnetocaloric material having a distinct Curie temperature, and wherein the first subsystem comprises a cold stage such that the distinct Curie temperatures of the distinct magnetocaloric materials in the first plurality of layers are in a range between T c  and T m ; and   the second bed comprises a second plurality of layers, wherein each layer of the second bed includes a distinct magnetocaloric material having a distinct Curie temperature, and wherein the second subsystem comprises a hot stage such that the distinct Curie temperatures of the distinct magnetocaloric materials in the second plurality of layers are in a range between T m  and T h , wherein T h >T m >T c .   
     
     
         21 . The heat transfer system of  claim 20 , wherein the first heat transfer fluid is at a temperature of T c  when the cold stage operates in the cooling mode, and wherein at least one of the first valve and the second valve direct the first heat transfer fluid at the temperature of T c  through the hot stage to regenerate the hot stage. 
     
     
         22 . The heat transfer system of  claim 20 , wherein the second heat transfer fluid is at a temperature of T h  when the hot stage operates in the cooling mode, and wherein at least one of the first valve and the second valve direct the second heat transfer fluid at the temperature of T h  through the cold stage to regenerate the cold stage.