Cooling device utilizing thermoelectric and magnetocaloric mechanisms for enhanced cooling applications

Abstract

This invention relates to a cooling device which utilizes both thermoelectric and magnetocaloric mechanisms for enhanced cooling applications. The incorporation of a magnetocaloric mechanism into a thermoelectric device provides additional cooling on the cold side of the device, and may improve the device efficiency, which is useful for many industrial applications, including cooling of microelectronic devices. Embodiments of the invention provide a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material, at least one permanent magnet, and at least one mechanical movement system. In some embodiments, the magnetocaloric component of the cooling device is optimized to provide enhanced cooling on the cold side of the cooling device.

What is claimed is: 
     
         1 . A cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material, at least one permanent magnet, and at least one mechanical movement system; wherein
 the thermoelectric element is configured to move heat from the cold side of the device to the hot side of the device when a DC current is applied in a specified direction; and wherein   the permanent magnet is positioned to generate a magnetic field that modulates the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, wherein a change in temperature of the magnetocaloric material occurs when the magnetocaloric material is moved into or out of a magnetic field; and wherein   the mechanical movement system is configured to perform the at least one oscillation cycle by physically moving the permanent magnet, the magnetocaloric material, a magnetic shielding material, or any combination thereof; and wherein   the at least one oscillation cycle comprises movement of the magnetic field towards the magnetocaloric material at a predefined magnetic field ramp-up speed, holding the magnetic field near or in contact with the magnetocaloric material for a specified contact holding time, moving the magnetic field away from the magnetocaloric material at a predefined ramp-down speed, and holding the magnetic field away from the magnetocaloric material for a specified removed holding time.   
     
     
         2 . The device of  claim 1 , wherein the thermoelectric element comprises a material selected from the group consisting of bismuth based alloys, lead telluride based alloys, carbon based materials, inorganic clathrate materials, magnesium based materials, silicides, skutterudite materials, oxide materials, Half Heusler alloys, silicon-germanium based materials, sodium-cobaltate based materials, or any combination thereof. 
     
     
         3 . The device of  claim 2 , wherein the thermoelectric pellets comprise at least one nano-grained material, wherein the nano-grained material has at least one of its dimensions in the range of about 1 nm to about 100 nm. 
     
     
         4 . The device of  claim 1 , wherein the magnetocaloric material is selected from the group consisting of Gd, Gd based alloys, NiMn based alloys, La based alloys, Nd based alloys, Dy based alloys, Pr based alloys, MnAs based alloys, Er based alloys, Tm based alloys, FeNi based alloys, and any combination thereof. 
     
     
         5 . The device of  claim 4 , wherein the temperature of the magnetocaloric material increases when the magnetic field is moved near or in contact with the magnetocaloric material, and wherein the temperature of the magnetocaloric material decreases when the magnetic field is moved away from the magnetocaloric material. 
     
     
         6 . The device of  claim 5 , wherein the magnetocaloric material comprises a Gd based alloy. 
     
     
         7 . The device of  claim 4 , wherein the magnetocaloric material exhibits an inverse magnetocaloric effect, wherein the temperature of the magnetocaloric material decreases when the magnetic field is moved near or in contact with the magnetocaloric material, and wherein the temperature of the magnetocaloric material increases when the magnetic field is moved away from the magnetocaloric material. 
     
     
         8 . The device of  claim 7 , wherein the magnetocaloric material is a NiMn based alloy. 
     
     
         9 . The device of  claim 4 , wherein the magnetocaloric material comprises at least one nano-grained material, wherein the nano-grained material has at least one of its dimensions in the range of about 1 nm to about 100 nm. 
     
     
         10 . The device of  claim 9 , wherein the magnetocaloric material further comprises Fe. 
     
     
         11 . The device of  claim 9 , wherein the mechanical movement system is designed to perform multiple oscillation cycles. 
     
     
         12 . The device of  claim 11 , wherein the magnetic field is moved towards the magnetocaloric material during the at least one oscillation cycle at a magnetic field ramp-up speed of between about 0.4 Tesla per second to about 3 Tesla per second. 
     
     
         13 . The device of  claim 12 , wherein the contact holding time of the magnetic field during the at least one oscillation cycle is between about 0.01 seconds to about 30 seconds. 
     
     
         14 . The device of  claim 13 , wherein the magnetic field is moved away from the magnetocaloric material during the at least one oscillation cycle at a magnetic field ramp-down speed of between about 3 Tesla per second to about 0.4 Tesla per second. 
     
     
         15 . The device of  claim 14 , wherein the removed holding time of the magnetic field during the at least one oscillation cycle is between about 0.01 seconds to about 30 seconds. 
     
     
         16 . The device of  claim 15 , wherein the mechanical movement system is powered by a separate electrical system from the thermoelectric element. 
     
     
         17 . The device of  claim 1 , further comprising a magnetic shielding material. 
     
     
         18 . The device of  claim 1 , wherein the permanent magnet is selected from the group consisting of a rare earth magnet, ceramic magnets, AlNiCo based magnets, or any combination thereof. 
     
     
         19 . The device of  claim 18 , wherein the permanent magnet material is selected from NdFeB, AlNiCo, SmCo, Ferrite, Femite, FeCrCo, or any combination thereof. 
     
     
         20 . The device of  claim 19 , wherein the permanent magnet has a magnetic field of between about 0.1 Tesla to about 2 Tesla. 
     
     
         21 . The device of  claim 20 , further comprising copper plates, copper wires, ceramic plates, ceramic spacers, ceramic substrates, magnetic shielding materials, adhesives, soldering materials, or any combination thereof. 
     
     
         22 . A method of removing unwanted heat from an apparatus or a surface comprising:
 a) contacting the cold side of the cooling device of  claim 1  to a surface of the apparatus,   b) applying the DC current to the thermoelectric element,   c) activating the mechanical movement system to perform the at least one oscillation cycle.   
     
     
         23 . The method of  claim 22 , wherein the hot side of the cooling device further comprises a heat sink and/or a convection cooling system.