MAGNETOCALORIC MATERIALS FOR CRYOGENIC LIQUIFICATION

• US 20150114007A1
• Filed: 10/25/2013
• Published: 04/30/2015
• Est. Priority Date: 10/25/2013
• Status: Active Grant

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Neilson, James R., McQueen, Tyrel M.
• Granted Patent: US 9,568,223 B2
• Time in Patent Office: Days
• US Class Current: 62/3.1
• CPC Class Codes: F25B 21/00 Machines, plants or systems, using electric or magnetic effects
• CPC Class Codes: F25B 2321/002 by using magneto-caloric effects
• CPC Class Codes: H01F 1/012 adapted for magnetic entropy change by magnetocaloric effect, e.g. used as magnetic refrigerating material refrigeration systems using magnetic effects F25B21/00
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]

Abstract

System and methods for cryogenic magnetocaloric refrigeration are provided. The system may include a magnetocaloric material including a single ion anisotropy and primary magnetic interactions of at most two dimensions. The system may also include a cryogenic fluid in communication with the magnetocaloric material, such that, when a magnetic field having a strength of at least a predetermined threshold is applied, the magnetocaloric material is configured to at least partially liquefy the cryogenic fluid.

Claims

1. A system for cryogenic magnetocaloric refrigeration, comprising:

a magnetocaloric material comprising a single ion anisotropy and primary magnetic interactions of at most two dimensions; and

a cryogenic fluid in communication with the magnetocaloric material, such that, when a magnetic field having a strength of at least a predetermined threshold is applied, the magnetocaloric material is configured to at least partially liquefy the cryogenic fluid.

2. The system of claim 1, further comprising a magnet in communication with the magnetocaloric material and configured to provide the magnetic field acting thereon.

3. The system of claim 2, wherein the predetermined threshold is between about 5 Tesla and about 9 Tesla.

4. The system of claim 1, wherein the magnetocaloric material comprises a transition metal.

5. The system of claim 4, wherein the transition metal is selected from a group consisting of Fe in a trigonal bipyramid crystal field, Co in an octahedral crystal field, and Mn.

6. The system of claim 4, wherein the magnetocaloric material comprises a non-magnetic main-group element.

7. The system of claim 6, wherein the magnetocaloric material comprises an alkali metal.

8. The system of claim 7, wherein the non-magnetic main-group element comprises boron.

9. The system of claim 1, wherein the magnetocaloric material comprises LiFeBO₃, LiMnBO₃, LiCoBO₃, or a combination thereof

10. The system of claim 1, wherein the magnetocaloric material undergoes a magnetic field-induced phase transition at a temperature of about 4 Kelvin and the cryogenic fluid comprises helium.

11. The system of claim 11, wherein the magnetic field-induced phase transition is first order.

12. A method of magnetocaloric cryogenic refrigeration, comprising:

applying a magnetic field to a magnetocaloric material, wherein applying causes the magnetocaloric material undergo a magnetic phase transition at a temperature less than or equal to a boiling temperature of a cryogenic fluid, and wherein the magnetocaloric material has a single ion anistropy and a magnetic structure of at most two dimensions;

removing heat from the magnetocaloric material while applying the magnetic field;

causing the cryogenic fluid, in a substantially gaseous phase, to come into thermal contact with the magnetocaloric material;

decreasing a strength of the magnetic field applied to the magnetocaloric material, such that the magnetocaloric material undergoes a reverse of the magnetic phase transition and absorbs heat from the cryogenic fluid in the substantially gaseous phase, so as to transition the cryogenic fluid to a substantially liquid phase; and

causing the cryogenic fluid in the substantially liquid phase to move away from the magnetocaloric material.

13. The method of claim 12, wherein the applying the magnetic field and decreasing the magnetic field are substantially adiabatic.

14. The method of claim 12, wherein the removing heat and causing the cryogenic fluid to move are substantially isomagnetic.

15. The method of claim 12, wherein the magnetic field has a strength of between about 5 Tesla and about 9 Tesla.

16. The method of claim 12, wherein the magnetocaloric material comprises Fe in a trigonal bipyramid crystal field, Co in an octahedral crystal field, Mn, or a combination thereof.

17. The method of claim 12, wherein the magnetocaloric material comprises a non-magnetic main-group element.

18. The method of claim 12, wherein the magnetic phase transition is a first-order magnetic phase transition.

19. The method of claim 12, wherein the temperature at which the magnetocaloric material undergoes the magnetic phase transition is within about 20% of the boiling temperature.

20. A magnetocaloric refrigeration system, comprising:

a magnetocaloric material comprising boron, lithium, and a transition metal, the transition metal being selected from a group consisting of Fe in a trigonal bypyramid crystal field, Co in an octrahedral crystal field, and Mn;

a magnet configured to provide a magnetic field having a strength of between about 5 Tesla and about 10 Tesla; and

a cryogenic fluid in communication with the magnetocaloric material, such that, when the magnetic field is applied and then removed from the magnetocaloric material, the magnetocaloric material is configured to at least partially liquefy the cryogenic fluid.