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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/240,484 filed on Oct. 12, 2015 entitled “Cooling Device Utilizing Thermoelectric and Magnetocaloric Mechanisms for Enhanced Cooling Applications”, the contents of which are incorporated herein by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED R&D

This invention is related to federally sponsored research and development under subawards SUB 20125266 (NOOJ73-14-J-GOJ6, Naval Research Laboratmy) and SUB 20163004 (DE-SCOOI 5932, Department of Energy). The invention was made with U.S. government support. The U.S. government has certain rights in the invention.

BACKGROUND OF THE INVENTION

Field of the Invention

Embodiments of the present invention generally relate 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 cooling 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.

Description of the Related Art

As refrigeration and cooling systems account for greater than 10 quads of U.S. primary energy consumption, a more efficient cooling technology could significantly reduce energy consumption, and have a profound impact on our society. Most conventional air conditioners, heat pumps, and refrigerators achieve cooling through a mechanical vapor compression cycle (VCC) which requires large amounts of energy and has an adverse environmental impact due to the use of hydrofluorocarbons (HFCs). New technologies that have made progress in the last decade are thermoelectric cooling (TEC) modules and magnetic refrigeration. TEC uses the Peltier effect which creates a heat flux by applying an electric field. The thermoelectric effect was described by H. J. Goldsmid, Thermoelectric Refrigeration, Plenum Press (1964). Magnetic refrigeration utilizes the magnetocaloric effect (MCE), which is the temperature variation of a magnetic material after exposure to a magnetic field. The magnetocaloric effect was first described by Weiss, Pierre and Piccard, Auguste, Journal of Physics, (7) 103 (1917).

TEC modules are at the forefront of new technology for many applications because they do not use liquids or pumps and have no moving parts, yielding an indefinite device lifetime. However, the drawback of current TEC technologies is their poor efficiency.

MCE technologies have also drawn tremendous attention due to the possibility of good energy efficiency and environmental friendliness. However, the MCE materials must operate in a predetermined temperature range and development of magnetic coolers that can span a large temperature range has, to this point, been unsuccessful.

While much work has been done on these two mechanisms separately, there are only a handful of references which utilize both mechanisms. Chinese Patent Application 103312230 discloses a magnetic heating thermoelectric generator where a magnetic force is used to generate the heat on the hot side of a thermoelectric module, thus allowing electricity generation across the thermoelectric module due to the temperature gradient between the hot side and cold side.

Additionally, several magnetocaloric refrigeration systems have been previously disclosed which incorporate thermoelectric elements. U.S. Pat. No. 6,588,215 discloses an apparatus and methods for performing switching in magnetic refrigeration systems using inductively coupled thermoelectric switches wherein the magnetic cooling system comprises a magnetocaloric material and at least one thermoelectric switch that is energized indirectly by a magnetic coupling, wherein the thermoelectric is used to switch between a heat rejection and heat absorption phase of a magnetic cooling cycle. PCT Patent application WO2007001290 disclosed a combination thermo-electric and magnetic refrigeration system wherein the refrigeration system comprises a compartment, a first cooling device, said first cooling device cooling said compartment and generating a magnetic field, and a second device, wherein said second device uses said generated magnetic field for additional cooling. D. J. Silva et. al, Applied Energy, 93, 570 (2012), developed a model for a solid state cooling module utilizing the magnetocaloric effect instead of thermoelectric materials. However, their theoretical device requires a non-existent insulative material whose thermal conductivity changes with application of a magnetic field.

SUMMARY OF THE INVENTION

Some embodiments of the present 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 thermoelectric element acts 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. In some embodiments, the magnetic field generated by the permanent magnet enables 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. In some embodiments, the mechanical movement system performs the at least one oscillation cycle by physically moving the permanent magnet, the magnetocaloric material, a magnetic shielding material, or any combination thereof. In some embodiments, 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. In some embodiments, the at least one oscillation cycle is optimized to provide maximum cooling on the cold side of the cooling device.

In some embodiments, the thermoelectric element comprises pellets of at least one p-type thermoelectric material and at least one n-type thermoelectric material, wherein the pellets are arranged electrically in series and thermally in parallel in between the hot side and cold side of the device.

Various thermoelectric materials can be used in the cooling device. In some embodiments, 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. In some embodiments, the thermoelectric material may be further doped to create either p-type or n-type thermoelectric material. In some embodiments, the thermoelectric material comprises doped or un-doped BiSbTe, doped or un-doped BiSb, doped or un-doped BiSeTe, doped or un-doped BiTe, or any combination thereof. In some embodiments, the thermoelectric pellets further comprise iron.

In some embodiments, 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.

In some embodiments, the efficiency (ZT) of the thermoelectric material is enhanced with application of a magnetic field.

The magnetocaloric effect includes any phenomenon in which the temperature change of a material is caused by exposing the material to a changing magnetic field.

In some embodiments, 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. In some embodiments, the magnetocaloric material comprises a Gd based alloy. In some embodiments, 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. In some embodiments, the magnetocaloric material is a NiMn based alloy.

Various magnetocaloric materials can be used in the cooling device. In some embodiments, the magnetocaloric material is selected from the group consisting of Gd, Gd based alloy's, 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. In some embodiments, the magnetocaloric material is a NiMn based alloy. In some embodiments, the magnetocaloric material further comprises Fe.

In some embodiments, 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.

There are many possible locations for incorporation of the magnetocaloric material into the cooling device. In some embodiments, the magnetocaloric material is electrically isolated from the thermoelectric material. In some embodiments, the magnetocaloric material is incorporated into the thermoelectric pellets, wherein the magetocaloric material is electrically connected to the thermoelectric material.

In some embodiments, the mechanical movement system is designed to perform multiple oscillation cycles. In some embodiments, 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 0.001 Tesla per second to about 3 Tesla per second. In some embodiments, the contact holding time of the magnetic field during the at least one oscillation cycle is between about 0.01 seconds to about 10 minutes. In some embodiments, 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 0.001 Tesla per second. In some embodiments, the removed holding time of the magnetic field during the at least one oscillation cycle is between about 0.01 seconds to about 10 minutes.

Various mechanical movement systems may be utilized to perform the at least one oscillation cycle of the cooling device. In some embodiments, the mechanical movement system is a linear system. In some embodiments, the mechanical movement system is a rotational system. In some embodiments, the mechanical movement system rotates the permanent magnet or magnets, wherein the rotation of the magnet or magnets acts to oscillate the magnitude of the magnetic field within the device.

In some embodiments, the cooling device further comprises magnetic shield materials that act to block the magnetic field from a specified area of the device. In some embodiments, the magnetic shield materials comprise a soft magnetic material. In some embodiments, soft-magnetic materials include Fe—Ni alloys, alloys based on Fe and Co, Fe—Al alloys, Fe—Si—Al alloys, alloys based on Fe—CoNi, or any combination thereof. In some embodiments, the mechanical movement system performs the at least one oscillation cycle by moving a magnetic shielding material, to block and/or expose the magnetocaloric material to a magnetic field.

The cooling device requires an electrical power supply for the thermoelectric component, as well as a power supply to operate the mechanical movement system. Various configurations of the power supply or supplies are possible. In some embodiments, the mechanical movement system is powered by a separate electrical system from the thermoelectric element. In some embodiments, the mechanical movement system is powered by the same DC current as the thermoelectric element. In some embodiments, the mechanical movement system is powered by the same DC current as the thermoelectric element, and wherein the mechanical movement system continuously performs oscillation cycles when the DC current is applied in a specified direction. In some embodiments, when the direction of the DC current is reversed from the specified direction, the cooling device operates only as a thermoelectric device wherein the mechanical system does not perform the at least one oscillation, and the hot side and cold side of the device are reversed.

Various methods may be used to fabricate the thermoelectric pellets. In some embodiments, the thermoelectric pellets are fabricated by hydraulic pressing, hot pressing, sintering, swagging, or any combination thereof.

Various methods may be used to fabricate the magnetocaloric material into pellet or plate or block form. In some embodiments, the magnetocaloric material is fabricated into the desired form for the cooling device by hydraulic pressing, hot pressing, sintering, swagging, or any combination thereof.

Any permanent magnet capable of producing a magnetic field large enough to induce the magnetocaloric effect of the magnetocaloric material may be used in the cooling device. In some embodiments, the permanent magnet is selected from the group consisting of a rare earth magnet, ceramic magnets, AlNiCo based magnets, or any combination thereof. In some embodiments, the permanent magnet material is selected from NdFeB, AlNiCo, SmCo, Ferrite, Femite, FeCrCo, or any combination thereof. In some embodiments, the permanent magnet has a magnetic field of between about 0.01 Tesla to about 2 Tesla. In some embodiments, the permanent magnet has a magnetic field of between about 0.1 Tesla to about 1.5 Tesla.

Additional materials or components may be used in the cooling device. In some embodiments, the cooling device further comprising copper plates, copper wires, ceramic plates, ceramic spacers, ceramic substrates, soft magnetic shielding materials, adhesives, soldering materials, frame and/or mounting substrates, or any combination thereof.

Some embodiments of the invention provide a method of removing unwanted heat from an apparatus or a surface comprising adhering the cool side of the disclosed cooling device to a surface of the apparatus, applying a DC current in a specified direction to activate the thermoelectric heat flux of the thermoelectric element, activating the mechanical movement system to perform the at least one oscillation cycle. In some embodiments of the method, the hot side of the cooling device further comprises a heat sink and/or a convection cooling system.

For purposes of summarizing aspects of the invention and the advantages achieved over the related art, certain objects and advantages of the invention are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

Further aspects, features and advantages of this invention will become apparent from the detailed description of the embodiments which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a thermoelectric module comprising at least one thermoelectric element.

FIG. 2 shows the change in the hot side and cold side temperature of a commercially available thermoelectric module during a single oscillation cycle of a magnetic field in vacuum at 300K.

FIG. 3 shows the temperature versus magnetic field during a single oscillation cycle of a pure Gd plate in vacuum at 300K.

FIG. 4 shows the change in the hot side and cold side temperature of a commercially available thermoelectric module with a magnetocaloric material attached to the hot side of the module during a single oscillation cycle of a magnetic field in vacuum at 300K.

FIG. 5 shows the change in the hot side and cold side temperature of a commercially available thermoelectric module with a magnetocaloric material attached to the cold side of the module during a single oscillation cycle of a magnetic field in vacuum at 300K.

FIG. 6 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material.

FIG. 7 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material.

FIG. 8 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material and a magnetic shield material is incorporated into the device.

FIG. 9 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material and a magnetic shield material is incorporated into the device.

FIG. 10 illustrates an embodiment of 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 mechanical movement system physically moves the permanent magnet.

FIG. 11 illustrates an embodiment of 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 a mechanical movement system physically moves the permanent magnet and a second mechanical movement system physically moves the magnetocaloric material.

FIG. 12 illustrates an embodiment of 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 mechanical movement system physically moves the permanent magnet, and wherein the magnetocaloric material is incorporated into the thermoelectric pellet as a magneto-thermoelectric pellet.

FIG. 13 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material and a magnetic shield material is incorporated into the device.

FIG. 14 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material.

FIG. 15 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material.

FIG. 16 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material and a magnetic shield material is incorporated into the device.

FIG. 17 illustrates an embodiment of 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 a mechanical movement system physically moves the permanent magnet and a second mechanical movement system physically moves the magnetocaloric material.

FIG. 18 illustrates an embodiment of 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 mechanical movement system physically moves the magnetocaloric material and a magnetic shield material is incorporated into the device.

DETAILED DESCRIPTION

While much work has been performed on the thermoelectric cooling and magnetocaloric mechanisms separately, no known work has documented the simultaneous use of both mechanisms to provide a solid state active cooling module. According to K. Yagasaki and A. T. Burkov, Encyclopedia of Materials: Science and Technology, Pg. 4757 (2008), the thermoelectric efficiency of some materials can be considerably enhanced in a magnetic field. R. Wolfe and G. E. Smith, Appl. Phys. Lett. 1, 5 (1962), showed that the cooling efficiency of a single-crystal Bi_0.88Sb_0.12 alloy increases by ˜2.8 times in the presence of a magnetic field. Surprisingly, the inventors have discovered that by incorporating a magnetocaloric material into a thermoelectric element and performing an oscillation cycle to induce the magnetocaloric effect, a significant decrease in the cold side temperature of the cooling device can be obtained. This enhanced cooling effect is useful for a variety of industrial applications which require cooling, such as, but not limited to cooling of microelectronic devices, cooling on space platforms, etc.

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 thermoelectric element acts 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. In some embodiments the magnetic field generated by the permanent magnet enables 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. In some embodiments the mechanical movement system performs the at least one oscillation cycle by physically moving the permanent magnet, the magnetocaloric material, a magnetic shielding material, or any combination thereof. In some embodiments the at least one oscillation cycle comprises exposing the magnetic field to the magnetocaloric material at a predefined magnetic field ramp-up speed, holding the magnetic field on the magnetocaloric material for a specified contact holding time, removing the magnetic field 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. In some embodiments the at least one oscillation cycle is optimized to provide maximum cooling on the cold side of the cooling device.

Thermoelectric cooling uses the Peltier effect to create a heat flux between the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC). It can be used either for heating or for cooling, however the main application is cooling. Good thermoelectric materials are typically heavily doped semiconductors. A single thermoelectric element comprises at least one p-type thermoelectric material and at least on n-type thermoelectric material. FIG. 1 shows a typical thermoelectric module 100 comprising a single thermoelectric element, wherein the thermoelectric element comprises a p-type thermoelectric material 101 and an n-type thermoelectric material 102, wherein copper contacts 103 are used to electrically connect the p-type and n-type materials in series, and wherein the p-type and n-type thermoelectric materials are arranged thermally in parallel in between ceramic substrates 104, and wherein an electric power source 105 applies a DC current 106 in a specified direction to move heat from the cold side of the device to the hot side of the device. For typical thermoelectric modules, the hot side and cold side of the device can be flipped by reversing the direction of the electric current.

There are many possible configurations for the thermoelectric element. In some embodiments the thermoelectric element comprises at least one p-type thermoelectric material and at least one n-type thermoelectric material. In some embodiments the thermoelectric materials are in the form of pellets. In some embodiments the thermoelectric pellets may be square, rectangular and/or cylindrical. The size of the thermoelectric pellets may vary depending on the application of the cooling device. In some embodiments the thermoelectric pellets have at least one dimension in the range of about 1 nm to about 1 inch. In some embodiments, the pellets have at least one dimension in the range of about 1 mm to about 1 cm. In some embodiments of the invention the pellets are arranged electrically in series in the cooling device. In some embodiments, electrically conductive contacts are used to electrically connect the pellets. Any electrically conductive material can be used to electrically connect the thermoelectric pellets. In some embodiments, the electrically conductive contacts are a metal such as copper, tin, nickel, or any combination thereof. In some embodiments, the thermoelectric pellets are arranged thermally in parallel, in between the hot side and cold side of the device. In some embodiments, a non-electrically conductive material is used as the hot side and cold side substrate. In some embodiments, the hot side and cold side substrate comprise a ceramic material. In some embodiments of the invention the thermoelectric element comprises pellets of at least one p-type thermoelectric material and at least one n-type thermoelectric material, and wherein the pellets are arranged electrically in series and thermally in parallel in between the hot side and cold side of the device.

Various thermoelectric materials can be used in the cooling device. Good thermoelectric materials are typically heavily doped semiconductors. Bismuth based alloys are well known in the art as high efficiency thermoelectric materials. In some embodiments, 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. In some embodiments, the thermoelectric material further comprises a dopant which causes the thermoelectric material to be n-type. In some embodiments, the thermoelectric material further comprises a dopant which causes the thermoelectric material to be p-type.

Thermoelectric modules typically comprise both a p-type thermoelectric material and an n-type thermoelectric material. In some embodiments, the thermoelectric element comprises both p-type (majority charge carrier of holes) and n-type (majority charge carrier of electrons) thermoelectric materials. Often materials are doped with various dopants to increase thermoelectric properties and/or improve the majority charge carrier of the material, i.e. either the p-type (hole carrier) or n-type (electron carrier) of the material. In some embodiments, the thermoelectric material comprises a dopant which causes the thermoelectric material to be p-type. In some embodiments, the thermoelectric material comprises a dopant which causes the thermoelectric material to be n-type. In some embodiments, both the p-type and n-type thermoelectric material comprise a bismuth based alloy. In some embodiments, the p-type thermoelectric material comprises BiSbTe, BiSb, BiTe, or any combination thereof. In some embodiments, the n-type thermoelectric material comprises BiSeTe, BiSe, TeSe, or any combination thereof. In some embodiments, both the p-type and n-type thermoelectric material comprise a carbon based material. In some embodiments, the p-type thermoelectric material comprises boron doped carbon nanotubes, doped nanodiamond, doped graphene, or any combination thereof. In some embodiments, the n-type thermoelectric material comprises nitrogen doped carbon nanotubes, doped nanodiamond, doped graphene, or any combination thereof.

The thermoelectric properties of materials are typically characterized by a dimensionless parameter known as the figure of merit, ZT, where T is the absolute temperature, and Z is given as Z=S²σ/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, and κ is the thermal conductivity. The higher the ZT the better the efficiency. There are several bismuth based alloys that have ZT values near 1 at room temperature.

The thermoelectric material in the cooling device may vary depending on the application in which the particular cooling device is used. The efficiency of thermoelectric materials varies depending on the temperature of operation. Therefore cooling devices which will be used at room temperature may use thermoelectric materials that exhibit high efficiency (high ZT) at room temperature. For some applications, the cooling device may be required to function at low temperatures. For some applications, the cooling device may be required to function at high temperatures. In some embodiments, the cooling device is used for space applications, wherein the cooling device is required to function at low temperatures. In some embodiments, the cooling device is used for cooling electronics at room temperature, wherein the cooling device is required to function at ambient temperatures. In some embodiments, the cooling device is used for cooling at high temperature, wherein the cooling device is required to function at high temperatures. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at or near room temperature. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 1K to about 2000K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 1K to about 40K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 30K to about 100K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 50K to about 150K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 100K to about 300K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 80K to about 180K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 150K to about 250K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 200K to about 300K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 250K to about 400K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 350K to about 500K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 450K to about 1000K. In some embodiments, the thermoelectric materials in the thermoelectric element exhibit thermoelectric properties at any temperature in the range of about 1000K to about 2000K. In some embodiments, low temperature thermoelectric materials are used in the thermoelectric element, which are selected from the group consisting of doped or un-doped BiSbTe alloys, doped or un-doped BiSbTeSe alloys, doped or un-doped CsBiTe alloys, doped or un-doped KBiS alloys, doped or un-doped KBiSe alloys, doped or un-doped BiTe alloys, doped or un-doped BiSb alloys, doped or un-doped SbTe alloys, doped or un-doped BiSeTe alloys, doped or un-doped CsBiSbTe alloys, doped or un-doped CsBiTeSe alloys, doped or un-doped CsRbBiTe alloys, or any combination thereof. In some embodiments, room temperature thermoelectric materials are used in the thermoelectric element, which are selected from the group consisting of doped or un-doped BiSbTe alloys, doped or un-doped BiSbTeSe alloys, doped or un-doped BiTe alloys, doped or un-doped BiSe alloys, doped or un-doped SbSe alloys, doped or un-doped BiTe alloys, doped or un-doped SbTe alloys, doped or un-doped BiSeTe alloys, doped or un-doped SiGe alloys, or any combination thereof. In some embodiments, the thermoelectric material may further comprise a dopant selected from the group consisting of N, B, K, S, InTe alloys, Sb, Se, Te, SbI alloys, or any combination thereof.

Various methods may be used to synthesize the thermoelectric pellets of the thermoelectric element. In some embodiments, the thermoelectric pellets comprise nanomaterials. P. K. Nguyen, K. H. Lee, J. Moon, S. I. Kim, K. A. Ahn, L. H. Chen, S. M. Lee, R. K. Chen, S. Jin, and A. E. Berkowitz, Nanotechnology, 23, 415604 (2012) showed that nanomaterials may have significantly improved efficiency ZT compared to their bulk counterparts because small particles/small grains have huge interfacial area, which scatters phonons and reduces lattice thermal conductivity. In some embodiments, 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. In some embodiments, a nano-grained thermoelectric material may be synthesized using various methods known in the art, such as, but not limited to, spark erosion, chemical precipitation, hydrothermal method, arc melting, chemical vapor deposition, physical vapor deposition, ball-milling, etc. In some embodiments, the nano-grained material is formed into a pellet structure by various methods known in the art, such as sintering, hydraulic pressing, swaging, hot pressing, or any other method which effectively packs powder material into solid pellet form. In some embodiments, the thermoelectric pellets will be soldered to electrical contacts and/or a ceramic substrate to form a thermoelectric element, and therefore, the pellet structure of the nano-grained material must be strong enough to withstand soldering temperatures and processing. In some embodiments, the pellet structure must also be strong enough to withstand the temperature cycles of the cooling device, wherein the various materials and components of the cooling device may expand and/or contract as the temperature of the device changes during its operation.

R. Wolfe and G. E. Smith, Appl. Phys. Lett. 1, 5 (1962), showed that the cooling efficiency of a single-crystal Bi_0.88Sb_0.12 alloy increases by ˜2.8 times in the presence of a magnetic field. Since then, there has been a handful of studies characterizing the enhancement of thermoelectric efficiency under magnetic field, most of which are for Bismuth antimony alloys. These studies are disclosed in C. B. Thomast and H. J. Goldsmid, Journal of Physics D: Applied Physics, 3 (1970), T. Aono, Japanese Journal of Applied Physics, 9 (7) (1970), and W. M. Yim and A. Amith, Solid-State Electronics, 15, 1141 (1972).

FIG. 2 shows the temperature versus time of a commercially available thermoelectric module 101 (purchased from Custom Thermoelectrics, Inc.) wherein a 6 W electric current 106 is applied to the device, wherein the device is under vacuum, and wherein the thermoelectric pellets 107 comprise a bismuth telluride material, and wherein thermocouples 108 are attached to the hot side and cold side of the device, and wherein a 3.0 Tesla magnetic field is applied to the device and the hot side temperature of the device increases by 0.3 C, indicating the application of the magnetic field affects the heat flux of the thermoelectric module.

The enhanced thermoelectric properties with magnetic field vary widely throughout the literature due to composition, differences in doping concentrations, even directional solidification and texturing may have significant effects on these materials thermoelectric, and magneto-thermoelectric properties. Depending on the thermoelectric materials that are used in the cooling device, the thermoelectric efficiency may or may not be enhanced in the presence of a magnetic field. In some embodiments, the efficiency of the thermoelectric material is enhanced with application of a magnetic field. In some embodiments, the magnitude of the magnetic field affects the efficiency of the thermoelectric material. In some embodiments, the ZT of the thermoelectric material is increased by a factor of between about 0.01 to about 5.0 when in the presence of a magnetic field of magnitude greater than 0.2 Tesla. In some embodiments, the ZT of the thermoelectric material is increased by a factor of between about 0.05 to about 3.0 when in the presence of a magnetic field of magnitude greater than 0.2 Tesla. In some embodiments, the ZT of the thermoelectric material is increased by a factor of between about 0.1 to about 1.0 when in the presence of a magnetic field of magnitude greater than 0.2 Tesla. In some embodiments, the ZT of the thermoelectric material is increased by a factor of between about 0.01 to about 0.05 when in the presence of a magnetic field of magnitude greater than 0.2 Tesla. In some embodiments, the ZT of the thermoelectric material is increased by a factor of between about 0.01 to about 0.1 when in the presence of a magnetic field of magnitude greater than 0.2 Tesla. In some embodiments, the ZT of the thermoelectric material is increased by a factor of greater than about 0.01, when in the presence of a magnetic field at any magnitude in the range of about 0.01 Tesla to about 10 Tesla. In some embodiments, the ZT of the thermoelectric material is increased by a factor of greater than about 0.01, when in the presence of a magnetic field at any magnitude in the range of about 0.2 Tesla to about 3 Tesla. In some embodiments, the ZT of the thermoelectric material is increased by a factor of greater than about 0.01, when in the presence of a magnetic field at any magnitude in the range of about 0.4 Tesla to about 2 Tesla.

Iron is easily magnetized when a magnetic field is applied and may act to locally amplify a magnetic field. R. D. McMichael, J. J. Ritter, and R. D. Shull, J. Appl. Phys., 73, (10) 6946 (1993), showed that the addition of iron nanoparticles to gadolinium-gallium composites increases the magnetocaloric response by a factor of 3-4, which may be due to a local field amplification effect. Therefore, incorporation of iron and/or its composites into the thermoelectric materials may act to locally amplify the magnetic field in the composite, and further enhance the efficiency of the material. In some embodiments, the thermoelectric material further comprises iron or any material, composite, or alloy comprising iron. In some embodiments the thermoelectric material comprises nanoparticles of iron or nanoparticles of any material, composite, or alloy comprising iron. In some embodiments, the thermoelectric pellets further comprise iron or any material, composite, or alloy comprising iron.

The magnetocaloric effect (MCE) is a phenomenon in which the temperature change of a suitable material is caused by exposing the material to a changing magnetic field. The magnetocaloric effect can be quantified with the equation below:

$\Delta T_{\mathrm{ad}}=-{\int }_{H_0}^{H_1}{\left(\frac{T}{C\left(T,H\right)}\right)}_H{\left(\frac{\partial M\left(T,H\right)}{\partial T}\right)}_HH$

where T is the temperature, H is the applied magnetic field, C is the heat capacity of the working magnet (refrigerant) and M is the magnetization of the refrigerant. The temperature change in the material is caused by a change in the entropy of the material.

In some embodiments the magnetic field generated by the permanent magnet enables 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. It is the object of the invention to utilize the additional cooling from the magnetocaloric material to further decrease the temperature achieved on the cold side of the cooling device.

As used herein, the term “magnetocaloric effect” includes any phenomenon in which the temperature change of a material is caused by exposing the material to a changing magnetic field.

The magnetocaloric effect exhibited by most magnetocaloric materials is as follows: 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. Materials which undergo a magnetocaloric effect with application and removal of a magnetic field include, but are not limited to, Gadolinium based alloys. In some embodiments, the magnetocaloric material exhibits a magnetocaloric effect, 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. In some embodiments, the magnetocaloric material comprises a Gd based alloy.

However, some magnetocaloric materials exhibit a inversed 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. Materials which undergo an inverse magnetocaloric effect with application and removal of a magnetic field include, but are not limited to, Heusler alloys, which include, but are not limited to, NiMn based alloys. In some embodiments, 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. In some embodiments, the magnetocaloric material is a NiMn based alloy.

FIG. 3 shows the temperature versus magnetic field during a single oscillation cycle of a pure Gd plate in vacuum at 300K, wherein the initial temperature of the Gd plate is 26 C, and wherein as the magnetic field increases to ˜3 Tesla, the temperature of the Gd plate increases to 28 C, and wherein the heat dissipates and the temperature of the Gd plate returns to 26 C while holding the magnetic field at ˜3 Tesla for 240 seconds, and wherein the magnetic field is removed and the temperature of the Gd plate decreases to 24 C. In some embodiments of the cooling device, the magnetic field generated by the permanent magnet enables 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.

Various magnetocaloric materials may be used in the cooling device. Magnetocaloric materials have been around for decades and are typically used to provide cooling at cryogenic temperatures (<1K). Several magnetic refrigerators for cryogenic applications are commercially available. Similar to thermoelectric materials, magnetocaloric materials only exhibit a magnetocaloric response in a specific temperature range. Therefore, depending on the application of the cooling device, an adequate magnetocaloric material must be used in the cooling device. In some embodiments, the magnetocaloric material is selected from the group consisting of Gd, Gd based alloy's, 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, or any combination thereof.

In some embodiments the cooling device is designed for low temperature applications, wherein the magnetocaloric material of the device comprises a material which exhibits a magnetocaloric effect at low temperature. In some embodiments the cooling device is designed for room temperature applications, wherein the magnetocaloric material of the device comprises a material which exhibits magnetocaloric effect at room temperature. In some embodiments the cooling device is designed for high temperature applications, wherein the magnetocaloric material of the device comprises a material which exhibits magnetocaloric effect at high temperature. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 1K to about 2000K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 1K to about 40K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 30K to about 100K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 50K to about 150K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 100K to about 200K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 80K to about 180K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 150K to about 250K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 200K to about 300K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 250K to about 400K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 350K to about 500K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 450K to about 1000K. In some embodiments, the magnetocaloric material in the cooling device exhibits a magnetocaloric effect at any temperature in the range of about 1000K to about 2000K.

Various magnetocaloric materials are available and can be used in the cooling device. In some embodiments the magnetocaloric material is selected from the group consisting of Gd, GdSiGe alloys, GdSiGeFe alloys, GdGeSiSn alloys, GdGa alloys, GdGaFe alloys, GdPd alloys, NiMnSn alloys, NiMnGa alloys, FeNiMn alloys, FeNiB alloys, FeNiZrB alloys, NiMnln alloys, NiMnlnCo alloys, NiMnCuGa alloys, NiMnSb alloys, NiMnCoSn alloys, NiCoMnln alloys, FeNi alloys, FeNiCo alloys, LaFe alloys, LaSi alloys, LaAl alloys, LaNiSi alloys, CeNiSi alloys, PrNiSi alloys, NdNiSi alloys, GdGaO alloys, DyAlO alloys, NdFe alloys, NdGaO alloys, NdAlO alloys, GdGaO alloys, GdAlO alloys, Dy GaO alloys, DyAlO alloys, Pr, Nd, ErAl alloys, HoAl alloys, DyAl alloys, DyHoAl alloys, DyErAl alloys, GdPdAl alloys, GdFeAl alloys, GdNi alloys, GdBiSn alloys, DyNi alloys, HoNi alloys, PrCoSi alloys, GdCoSi alloys, LaCoSi alloys, LaCaMnO alloys, LaFeSi alloys, MnAs alloys, MnGe alloys, MnCuAs alloys, MnAsSb alloys, MnFePAs alloys, MnAsFe alloys, MnFePGe alloys, LaFeAl alloys, LaFeCoSi alloys, LaPrFeCoSi alloys, LaPrFeSi alloys, LaFeMnSi alloys, LaNdFeSi alloys, LaCeFeSi alloys, LaPrFeSi alloys, LaFeSiH alloys, LaFeMnSiH alloys, LaFeSiC alloys, LaNdFeCoSi alloys, LaFeCoAl alloys, CdCrS alloys, CdCuCrS alloys, CdFeCrS alloys, CeFeMnB alloys, or any combination thereof.

In some embodiments, the magnetocaloric response of the magnetocaloric material may be broadened (temperature span of magnetocaloric response) or enhanced (magnitude of magnetocaloric response) by decreasing the grain size in the material. In some embodiments, 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. In some embodiments, the nanograins of the magnetocaloric material are synthesized by methods known in the art, such as, but not limited to, spark erosion, ball milling, hydrothermal method, chemical precipitation synthesis, arc melting, chemical vapor deposition, physical vapor deposition, etc. In some embodiments, the nano-grained magnetocaloric material is formed into a pellet structure by various methods known in the art, such as sintering, hydraulic pressing, swaging, hot pressing, or any other method which effectively packs powder material into solid pellet form. In some embodiments, the magnetocaloric pellet will be soldered to electrical contacts and/or a ceramic substrate and/or mechanical movement system to form the cooling device, and therefore, the pellet structure of the nano-grained material must be strong enough to withstand soldering and/or adhesive temperatures and processing. In some embodiments, the pellet structure must also be strong enough to withstand the temperature cycles of the cooling device, wherein the various materials and components of the cooling device may expand and/or contract as the temperature of the device changes during its operation.

R. D. McMichael, J. J. Ritter, and R. D. Shull, J. Appl. Phys., 73, (10) 6946 (1993), showed that the addition of iron nanoparticles to gadolinium-gallium composites increases the magnetocaloric response by a factor of 3-4, which may be due to a local field amplification effect. Therefore, incorporation of iron and/or its composites into the magnetocaloric material may act to locally amplify the magnetic field in the material, and further enhance the magnetocaloric response of the material. In some embodiments, the magnetocaloric material further comprises iron or any material, composite, or alloy comprising iron. In some embodiments the magnetocaloric material comprises nanoparticles of iron or nanoparticles of any material, composite, or alloy comprising iron. In some embodiments, the magnetocaloric pellets further comprise iron or any material, composite, or alloy comprising iron.

Various structures of the cooling device are possible. In some embodiments, the magnetocaloric material is located outside of the thermoelectric element, wherein the magnetocaloric material is outside of the hot side and cold side substrates in which the thermoelectric element is thermally in parallel. In some embodiments, the magnetocaloric material may be located within the thermoelectric element, meaning within the hot side and cold side substrates in which the thermoelectric element is thermally in parallel. In some embodiments, the magnetocaloric material is located in between the hot side and cold side substrates. In some embodiments, the magnetocaloric material is electrically isolated from the thermoelectric material. In some embodiments, the magnetocaloric material is incorporated into the thermoelectric pellets.

The mechanical movement system performs the at least one oscillation cycle. In some embodiments the mechanical movement system performs the at least one oscillation cycle by physically moving the permanent magnet, the magnetocaloric material, a magnetic shielding material, or any combination thereof. In some embodiments, the mechanical movement system is designed to perform multiple oscillation cycles. In some embodiments the mechanical movement system is a linear system. In some embodiments the mechanical movement system is a rotational system. In some embodiments, the cooling device has both a linear and rotational mechanical movement system. In some embodiments, the mechanical movement system linearly moves the magnetocaloric material, wherein the linear movement of the magnetocaloric material acts to move the magnetocaloric material into and out of the magnetic field. In some embodiments, the mechanical movement system linearly moves the permanent magnet, wherein the linear movement of the permanent magnet acts to move the magnetocaloric material into and out of the magnetic field. In some embodiments, the mechanical movement system rotates the permanent magnet or magnets, wherein the rotation of the magnet or magnets acts to oscillate the magnetic field force within the device.

Various mechanical systems may be used as the mechanical movement system. In some embodiments, electronic linear actuators are used to linearly move the permanent magnet or magnets, magnetocaloric material or materials, magnetic shielding material or materials, or any combination thereof. In some embodiments, an electronic rotational actuator is used to linearly move the permanent magnet or magnets, magnetocaloric material or materials, magnetic shielding material or materials, or any combination thereof. The size and number of actuators needed depends on the device structure. Various methods may be used to mount the material to be moved to a frame or substrate, wherein a single actuator then moves the entire substrate with the material or materials mounted on it. The chosen mechanical movement system must be compatible with the magnetic field generated by the permanent magnets. The mechanical movement system must also be strong enough to perform the at least one oscillation cycle with the fluctuations of the magnetic field, and the tendency of the magnets along with the magentocaloric materials to attract and repel from each other, and/or other materials within the device. In some embodiments, the magnets and the magnetocaloric materials are mounted on substrates or frame materials using a method that is strong enough to hold the materials in place during the at least one oscillation cycle.

The magnetic field of the permanent magnet is strongest at the surface of the magnet and decreases with distance from the magnet. The distance required for the mechanical movement system to move the magnetic field towards and away from the magnetic field depends on the magnitude of the magnetic field produced by the permanent magnet, which will also vary depending on the size and material type of the permanent magnet. Maximizing the change in the magnitude of the magnetic field will maximize the magnetocaloric response of the magnetocaloric material. In order to increase the change in temperature of the magnetocaloric material, in some embodiments, it is desirable for the mechanical movement system to apply a magnetic field of greater than about 0.01 Tesla, greater than about 0.1 Tesla, greater than about 0.2 Tesla, greater than about 0.4 Tesla, greater than about 0.6 Tesla, greater than about 0.8 Tesla, or greater than about 1 Tesla. In order to increase the change in temperature of the magnetocaloric materials, in some embodiments, it is desirable for the mechanical movement system to remove the magnetic field so that the magnitude of the magnetic field on the magnetocaloric material is less than about 0.2 Tesla, less than about 0.1 Tesla, less than about 0.05 Tesla, less than about 0.02 Tesla, less than about 0.01 Tesla, or less than about 0.001 Tesla. The distance the mechanical movement system moves the magnetocaloric material, the permanent magnet, or both, should be optimized to apply the desired magnetic field magnitude during the at least one oscillation cycle. In some embodiments, a linear mechanical movement system is used in the cooling device and the distance required to perform the at least one oscillation cycle which provides an acceptable temperature variation of the magnetocaloric material, is less than about 2 cm, less than about 1 cm, less than about 5 mm, less than about 2 mm, or less than about 1 mm.

In some embodiments 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. In some embodiments, 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 0.001 Tesla per second to about 3 Tesla per second. In some embodiments, the contact holding time of the magnetic field during the at least one oscillation cycle is between about 0.01 seconds to about 10 minutes. In some embodiments, 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 0.001 Tesla per second. In some embodiments, the removed holding time of the magnetic field during the at least one oscillation cycle is between about 0.01 seconds to about 10 minutes.

The cooling device must be powered by at least one electrical power source. The thermoelectric element requires a DC current to be applied in a specified direction. In some embodiments, the mechanical movement system is powered by a separate electrical system from the thermoelectric element. In some embodiments the mechanical movement system is powered by the same DC current as the thermoelectric element, and wherein the mechanical movement system continuously performs oscillation cycles when the DC current is applied in a specified direction. In some embodiments, when the direction of the DC current is reversed from the specified direction, the cooling device operates only as a thermoelectric device wherein the mechanical system does not perform the at least one oscillation, and the hot side and cold side of the device are reversed.

There are many different methods of controlling the operation of the cooling device. In some embodiments, a single electrical power system is used to supply an electrical current to both the thermoelectric element, and the mechanical movement system, such that when the power system is turned on, the device operates continuously to provide cooling until the device is powered off. In some embodiments, a more sophisticated controller may be used to control or regulate the cooling device. In some embodiments, a computer is connected to the power source of the thermoelectric element, the mechanical motion system, or both, and wherein a software program on the computer control system can be programmed to turn the power off and on to the various systems at specified time intervals. In some embodiments, thermocouples may also be included at various positions in the cooling device and/or on the apparatus which is being cooled, wherein the thermocouples relay the temperature to the computer control system which is programmed to adjust the DC power supply to the thermoelectric element, the mechanical motion system, or both, in order to increase or decrease the cooling rate of the cooling device. In some embodiments, the cooling device further comprises a control system. In some embodiments, the cooling device comprises an electronics control system such as the Arduino system. In some embodiments, a computer software program such as Solidworks is programmed to control the operation of cooling device.

It is the object of the invention to utilize the additional cooling from the magnetocaloric material to further decrease the temperature achieved on the cold side of the cooling device. FIGS. 4 and 5 illustrate temperature versus time data of simple cooling device structures which have both thermoelectric and magnetocaloric components. For FIGS. 4 and 5 the magnetic field is applied using an electromagnet. A significantly lower cold side temperature can be achieved by placing the magnetocaloric material on the cold side versus the hot side, which indicates the performance of the cooling device structure can be significantly altered depending on its structure. In some embodiments the at least one oscillation cycle is optimized to provide additional cooling on the cold side of the cooling device. In some embodiments, the structure of the cooling device is optimized to provide significantly enhanced cooling efficiency compared to thermoelectric devices which do not incorporate a magnetocaloric component.

FIG. 4 shows the temperature versus time of a commercially available thermoelectric module 101 (purchased from Custom Thermoelectrics, Inc.), wherein the magnetocaloric material 109 comprises a Gd plate, wherein the Gd plate is adhered to the hot side of the thermoelectric module, wherein the device is under vacuum, and wherein the thermoelectric pellets 107 comprise a bismuth telluride material, wherein thermocouples 108 are attached to the top of the Gd plate and the cold side of the device, wherein a 6 W electric current 106 is applied to the thermoelectric module, wherein the hot side and cold side temperatures stabilize at 34.9 C and 15.9 C, respectively, wherein a magnetic field is applied (electromagnet is used to apply magnetic field force) to the device at a ramp-up rate of 0.03 Tesla per second up to a magnitude of 3 Tesla, and wherein the hot side temperature of the device increases by 1.2 C and the cold side temperature of the device increases by 0.6 C, and wherein the magnetic field is held at 3 Tesla for 240 seconds and the hot side and cold side temperatures of the device returns to 34.9 C and 15.9 C, respectively, wherein the magnetic field is completely removed at a ramp-down speed of 0.3 Tesla per second, and wherein the hot side temperature of the device decreases by 0.6 C and the cold side temperature of the device decreases by 0.6 C.

FIG. 5 shows the temperature versus time of a commercially available thermoelectric module 101 (purchased from Custom Thermoelectrics, Inc.), wherein the magnetocaloric material 109 comprises a Gd plate, wherein the Gd plate is adhered to the cold side of the thermoelectric module, wherein the device is under vacuum, and wherein the thermoelectric pellets 107 comprise a bismuth telluride material, wherein thermocouples 108 are attached to the bottom of the Gd plate and the hot side of the device, wherein a 6 W electric current 106 is applied to the thermoelectric module, wherein the hot side and cold side temperatures stabilize at 35.4 C and 16.4 C, respectively, wherein a magnetic field is applied (electromagnet is used to apply magnetic field force) to the device at a ramp-up rate of 0.03 Tesla per second up to a magnitude of 3 Tesla, and wherein the hot side temperature of the device increases by 0.6 C and the cold side temperature of the device increases by 0.9 C, and wherein the magnetic field is held at 3 Tesla for 240 seconds and the hot side and cold side of the device return to 35.4 C and 16.4 C, respectively, wherein the magnetic field is completely removed at a ramp-down speed of 0.3 Tesla per second, and wherein the hot side temperature of the device decreases by 0.6 C and the cold side temperature of the device decreases by 1.3 C.

The temperature variation of the magnetocaloric material occurs with the application and removal of a magnetic field. The cooling device therefore requires a magnetic field force, which can be generated by permanent magnets. In some embodiments the cooling device comprises a permanent magnet. In some embodiments, the permanent magnet is selected from the group consisting of rare earth magnets, ceramic magnets, AlNiCo based magnets, or any combination thereof. In some embodiments, the permanent magnet comprises a material is selected from NdFeB, AlNiCo, SmCo, Ferrite, Femite, FeCrCo, or any combination thereof. The magnitude of the magnetic field will vary depending on distance from the surface of the magnet. In some embodiments, the permanent magnet has a magnetic field at the surface of the magnet of between about 0.01 Tesla to about 2 Tesla. In some embodiments, the permanent magnet has a magnetic field at the surface of the magnet of between about 0.1 Tesla to about 1.6 Tesla. In some embodiments, the permanent magnet has a magnetic field at the surface of the magnet of between about 0.4 Tesla to about 1.2 Tesla.

Additional materials and components may be incorporated into the cooling device. In some embodiments, the cooling device further comprises electrically conductive materials such as, but not limited to, copper plates or wires, alumina plates or wires, or electrically conductive adhesives, or soldering material. In some embodiments, the cooling device further comprises non-conductive materials such as, but not limited to, substrates such as ceramic plates, ceramic spacers, metal oxide casings, adhesives, sealing polymer materials. In some embodiments, the cooling device further comprises magnetic shield materials that act to block the magnetic field from a specified area of the device. In some embodiments, the magnetic shield materials comprise a soft magnetic material. In some embodiments, soft-magnetic materials include Fe—Ni alloys, alloys based on Fe and Co, Fe—Al alloys, Fe—Si—Al alloys, alloys based on Fe—CoNi, or any combination thereof.

Magnetocaloric refrigerators often incorporate a fluid system to remove heat generated by the magnetocaloric material. In some embodiments the cooling device may further comprise a fluid system designed to remove the heat generated by the magnetocaloric material or materials. In some embodiments, the fluid may be a gas such as, but not limited to, air, or a liquid, such as, but not limited to, water. In some embodiments the fluid may be pumped through the cooling device. In some embodiments, a fan may be used to flow air through the device.

Some embodiments of the invention provide a method of removing unwanted heat from an apparatus or a surface comprising adhering the cool side of the disclosed cooling device to a surface of the apparatus, applying a DC current in a specified direction to activate the thermoelectric heat flux of the thermoelectric element, activating the mechanical movement system to perform the at least one oscillation cycle. In some embodiments of the method, the hot side of the cooling device further comprises a heat sink and/or a convection cooling system.

For purposes of summarizing aspects of the invention and the advantages achieved over the related art, certain objects and advantages of the invention are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

Further aspects, features and advantages of this invention will become apparent from the detailed example embodiments which follow.

FIGS. 6-18 illustrate example embodiments of the invention. FIGS. 6-13 illustrate embodiments of the invention which use magnetocaloric materials that have a normal magnetocaloric effect when exposed to a changing magnetic field (temperature of magnetocaloric material increases when magnetic field is applied). FIGS. 14-18 illustrate embodiments of the invention which use magnetocaloric materials that have an inverse magnetocaloric effect when exposed to a changing magnetic field (temperature of magnetocaloric material decreases when magnetic field is applied). The embodiments will be explained with respect to preferred embodiments which are not intended to limit the present invention. Further, in the present disclosure where conditions and/or structures are not specified, the skilled artisan in the art can readily provide such conditions and/or structures, in light of the teachings herein, as a matter of routine experimentation.

FIG. 6 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material, wherein ceramic spacers 112 separate the magnetocaloric materials, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials horizontally above the hot side the cooling device.

FIG. 7 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material or materials, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials vertically in between the hot side and cold side of the cooling device.

FIG. 8 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials horizontally above the hot side the cooling device, wherein a magnetic shield material 113 is incorporated into the cooling device at a location which acts to block the magnetic field so that when the magnetocaloric material is in contact with the magnetic shield the magnitude of the magnetic field on the magnetocaloric material is near zero (H˜0).

FIG. 9 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials vertically in between the hot side and cold side of the cooling device, wherein magnetic shield materials 113 are incorporated into the cooling device at locations which act to block the magnetic field so that when the magnetocaloric material is near or in contact with the magnetic shield the magnitude of the magnetic field on the magnetocaloric material is near zero (H˜0). The cooling device structure of FIG. 9 has the advantage of providing a constant magnetic field on the thermoelectric material, which may significantly increase the efficiency of the thermoelectric material, while also allowing the magnetic field oscillation cycle needed for the magnetocaloric material to provide additional cooling.

FIG. 10 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet or magnets enables the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the permanent magnet, wherein the mechanical movement system is a rotational system which moves a smaller cylindrical permanent magnet which is located inside of a larger cylindrical permanent magnet, wherein the magnetocaloric material is located in between the small and large cylindrical permanent magnets, wherein the poles of the cylindrical magnets are located such that with rotation of the smaller cylindrical magnet, the magnitude of the magnetic field in between the small and large cylindrical permanent magnets ranges from H˜0 to H>0, wherein the magnetocaloric material or materials are stationary in between the hot side and cold side of the cooling device.

FIG. 11 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet or magnets enables the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the permanent magnet, wherein the mechanical movement system is a rotational system which moves a smaller cylindrical permanent magnet which is located inside of a larger cylindrical permanent magnet, wherein the magnetocaloric material is located in between the small and large cylindrical permanent magnets, wherein the poles of the cylindrical magnets are located such that with rotation of the smaller cylindrical magnet, the magnitude of the magnetic field in between the small and large cylindrical permanent magnets ranges from H˜0 to H>0, wherein a second mechanical movement system is used to vertically move the magnetocaloric material or materials in between the hot side and cold side of the cooling device.

FIG. 12 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet or magnets enables the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the permanent magnet, wherein the mechanical movement system is a rotational system which moves a smaller cylindrical permanent magnet which is located inside of a larger cylindrical permanent magnet, wherein the magnetocaloric material is combined with a thermoelectric material to form a magneto-thermoelectric pellet 114, wherein the magneto-thermoelectric pellets are located in between the small and large cylindrical permanent magnets, wherein the poles of the cylindrical magnets are located such that with rotation of the smaller cylindrical magnet, the magnitude of the magnetic field in between the small and large cylindrical permanent magnets ranges from H˜0 to H>0, wherein the magneto-thermoelectric pellet or pellets are stationary in between the hot side and cold side of the cooling device, and wherein the magneto-thermoelectric pellets are connected electrically in series and thermally in parallel.

FIG. 13 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials vertically in between the hot side and cold side of the cooling device, wherein magnetic shield materials 113 are incorporated into the cooling device at locations which act to block the magnetic field so that when the magnetocaloric material is near or in contact with the magnetic shield the magnitude of the magnetic field on the magnetocaloric material is near zero (H˜0).

FIG. 14 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the inverse magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material, wherein ceramic spacers 112 separate the magnetocaloric materials, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials horizontally above the hot side the cooling device.

FIG. 15 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the inverse magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material or materials, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials vertically in between the hot side and cold side of the cooling device.

FIG. 16 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the inverse magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials vertically in between the hot side and cold side of the cooling device, wherein magnetic shield materials 113 are incorporated into the cooling device at locations which act to block the magnetic field so that when the magnetocaloric material is near or in contact with the magnetic shield the magnitude of the magnetic field on the magnetocaloric material is near zero (H˜0). The cooling device structure of FIG. 16 has the advantage of providing a constant magnetic field on the thermoelectric material, which may significantly increase the efficiency of the thermoelectric material, while also allowing the magnetic field oscillation cycle needed for the magnetocaloric material to provide additional cooling.

FIG. 17 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet or magnets enables the inverse magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the permanent magnet, wherein the mechanical movement system is a rotational system which moves a smaller cylindrical permanent magnet which is located inside of a larger cylindrical permanent magnet, wherein the magnetocaloric material is located in between the small and large cylindrical permanent magnets, wherein the poles of the cylindrical magnets are located such that with rotation of the smaller cylindrical magnet, the magnitude of the magnetic field in between the small and large cylindrical permanent magnets ranges from H˜0 to H>0, wherein a second mechanical movement system is used to vertically move the magnetocaloric material or materials in between the hot side and cold side of the cooling device.

FIG. 18 illustrates an embodiment of a cooling device comprising a hot side, a cold side, at least one thermoelectric element, at least one magnetocaloric material 109, at least one permanent magnet 110, and at least one mechanical movement system 111, wherein the thermoelectric element comprises thermoelectric pellets 107, wherein the thermoelectric element acts to move heat from the cold side of the device to the hot side of the device when a DC current 106 is applied in a specified direction, wherein the magnetic field generated by the permanent magnet enables the inverse magnetocaloric effect of the magnetocaloric material when at least one oscillation cycle is performed by the mechanical movement system, 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, wherein the mechanical movement system performs the at least one oscillation cycle by physically moving the magnetocaloric material, wherein the mechanical movement system is a linear system which moves the magnetocaloric material or materials vertically in between the hot side and cold side of the cooling device, wherein magnetic shield materials 113 are incorporated into the cooling device at locations which act to block the magnetic field so that when the magnetocaloric material is near or in contact with the magnetic shield the magnitude of the magnetic field on the magnetocaloric material is near zero (H˜0).

The object of this current invention is to provide a solid-state cooling device which utilizes both thermoelectric and magnetocaloric mechanisms for enhanced cooling applications. As illustrated by the above example embodiments, the incorporation of a magnetocaloric mechanism into a thermoelectric device provides additional cooling on the cold side of the device, and can improve the device cooling efficiency, which may be very useful for many applications including cooling of microelectronic devices.

For purposes of summarizing aspects of the invention and the advantages achieved over the related art, certain objects and advantages of the invention are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present invention. Therefore, it should be clearly understood that the forms of the present invention are illustrative only and are not intended to limit the scope of the present invention.

Claims

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.