USE OF UNIDIRECTIONAL FLOW MODES OF MAGNETIC COOLING SYSTEMS

• US 20140165595A1
• Filed: 12/13/2013
• Published: 06/19/2014
• Est. Priority Date: 12/17/2012
• Status: Active Grant

• Current Assignee: Astronautics Corporation of America
• Original Assignee: Astronautics Corporation of America
• Inventors: ZIMM, Carl B., RUSSEK, Steven L., BOEDER, Andre
• Granted Patent: US 9,746,214 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: F25B 2321/0022 with a rotating or otherwise moving magnet
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]

Abstract

A dual-mode magnetic refrigeration apparatus includes beds of magnetocaloric material, a magnet to apply a time-varying magnetic field to the beds, a heat transfer fluid (HTF), a pump to circulate the HTF, a hot side heat exchanger (HHEX), a cold side heat exchanger (CHEX), valves to direct flow of the HTF, and a controller configured to control periodic switching of the valves to allow the apparatus to operate in a first mode and in a second mode. The first mode transfers heat from the CHEX to the HHEX. In the second mode of operation, the periodic switching of the valves is suspended to allow unidirectional flow of the HTF through the HHEX, the beds, and the CHEX such that heat is transferred from the HHEX to the CHEX.

Claims

1. A dual-mode magnetic refrigeration apparatus, comprising:

one or more beds of magnetocaloric material;

a magnet to apply a time-varying magnetic field to the one or more beds of magnetocaloric material;

a heat transfer fluid;

a pump to circulate the heat transfer fluid;

a hot side heat exchanger (HHEX);

a cold side heat exchanger (CHEX);

one or more valves to direct flow of the heat transfer fluid; and

a controller configured to control periodic switching of the one or more valves to allow the apparatus to operate in a first mode and in a second mode, wherein in the first mode the one or more valves direct the heat transfer fluid to a cold end of the one or more beds through the one or more beds to a hot end of the one or more beds and through the HHEX when the time-varying magnetic field applied to the one or more beds is high, and to the hot end of the one or more beds through the one or more beds to the cold end of the one or more beds and through the CHEX when the time-varying magnetic field applied to the one or more beds is low, in order to transfer heat from the CHEX to the HHEX; and

wherein in the second mode of operation, the periodic switching of the one or more valves is suspended to allow unidirectional flow of the heat transfer fluid through the HHEX, the one or more beds, and the CHEX such that heat is transferred from the HHEX to the CHEX.

2. The apparatus of claim 1, wherein a cycle time of the time-varying magnetic field is longer in the second mode than in the first mode.

3. The apparatus of claim 1, wherein the time-varying magnetic field applied to the one or more beds is suspended during the second mode.

4. The apparatus of claim 1, wherein during the second mode the CHEX is at a temperature at or above 0 degrees Celsius.

5. The apparatus of claim 1, wherein during the first mode the CHEX is at a temperature at or below 0 degrees Celsius.

6. The apparatus of claim 1, further comprising a fan that is configured to direct air over the CHEX.

7. The apparatus of claim 6, wherein the controller is configured to control the fan to direct air over the CHEX during the first mode.

8. The apparatus of claim 6, wherein the controller is configured to control the fan to not direct air over the CHEX during the second mode.

9. The apparatus of claim 1, wherein the one or more valves are electrically controlled valves.

10. The apparatus of claim 1, wherein the magnet is configured to move in relation to the one or more beds to effectuate the time-varying magnetic field.

11. The apparatus of claim 10, wherein the controller is configured to suspend movement of the magnet in relation to the one or more beds to effectuate the second mode.

12. The apparatus of claim 1, wherein the one or more beds are configured to move in relation to the magnet to effectuate the time-varying magnetic field.

13. The apparatus of claim 12, wherein the controller is configured to suspend movement of the one or more beds in relation to the magnet to effectuate the second mode.

14. The apparatus of claim 1, wherein the controller is configured to control the apparatus to operate in the second mode for a certain amount of time relative to the operation of the first mode.

15. The apparatus of claim 1, wherein the controller is configured to control the apparatus to operate in the second mode when the CHEX reaches a particular temperature.

16. The apparatus of claim 1, wherein the controller is configured to control the apparatus to operate in the second mode when the CHEX is at a particular temperature for a particular duration of time.

17. The apparatus of claim 1, wherein the controller is configured to control the apparatus to operate in the second mode when a compartment cooled by the CHEX is at a particular temperature.

18. The apparatus of claim 1, wherein the controller is configured to control the apparatus to operate in the first mode when a compartment cooled by the CHEX is at a particular temperature.

19. The apparatus of claim 1, wherein the controller is configured to introduce cold air from a first compartment cooled by the CHEX into a second compartment wherein the first compartment is maintained by the controller at a temperature below 0 degrees Celsius and the second compartment is maintained by the controller at a temperature above 0 degrees Celsius.

20. A dual-mode magnetic refrigeration apparatus, comprising:

one or more beds of magnetocaloric material;

a magnet to apply a time-varying magnetic field to the one or more beds of magnetocaloric material;

a heat transfer fluid;

a pump to circulate the heat transfer fluid;

a hot side heat exchanger (HHEX);

a cold side heat exchanger (CHEX);

one or more valves to direct flow of the heat transfer fluid; and

a controller configured to control periodic switching of the one or more valves to allow the apparatus to operate in a first mode and in a second mode, wherein in the first mode the one or more valves direct the heat transfer fluid to a cold end of the one or more beds through the one or more beds to a hot end of the one or more beds and through the HHEX when the time-varying magnetic field applied to the one or more beds is high, and to the hot end of the one or more beds through the one or more beds to the cold end of the one or more beds and through the CHEX when the time-varying magnetic field applied to the one or more beds is low, in order to transfer heat from the CHEX to the HHEX when an environment of the HHEX is at a similar or higher temperature than an environment of the CHEX; and

wherein in the second mode of operation, the periodic switching of the one or more valves is suspended to allow unidirectional flow of the heat transfer fluid through the HHEX, the one or more beds, and the CHEX such that heat is transferred from the CHEX to the HHEX when an environment of the HHEX is at a lower temperature than an environment of the CHEX.

21. The apparatus of claim 20, wherein a cycle time of the time-varying magnetic field is longer in the second mode than in the first mode.

22. The apparatus of claim 20, wherein the time-varying magnetic field applied to the one or more beds is suspended during the second mode.

23. The apparatus of claim 20, wherein the one or more valves are electrically controlled valves.

24. The apparatus of claim 20, wherein the magnet is configured to move in relation to the one or more beds to effectuate the time-varying magnetic field.

25. The apparatus of claim 24, wherein the controller is configured to suspend movement of the magnet in relation to the one or more beds to effectuate the second mode.

26. The apparatus of claim 20, wherein the one or more beds are configured to move in relation to the magnet to effectuate the time-varying magnetic field.

27. The apparatus of claim 26, wherein the controller is configured to suspend movement of the one or more beds in relation to the magnet to effectuate the second mode.

28. A dual-mode magnetic refrigeration apparatus with bypass, comprising:

one or more beds of magnetocaloric material;

a magnet to apply a time-varying magnetic field to the one or more beds of magnetocaloric material;

a heat transfer fluid;

a pump to circulate the heat transfer fluid;

a hot side heat exchanger (HHEX);

a cold side heat exchanger (CHEX);

one or more valves to direct flow of the heat transfer fluid; and

a controller configured to control periodic switching of the one or more valves to allow the apparatus to operate in a first mode and in a second mode, wherein in the first mode the one or more valves direct the heat transfer fluid to a cold end of the one or more beds through the one or more beds to a hot end of the one or more beds and through the HHEX when the time-varying magnetic field applied to the one or more beds is high, and to the hot end of the one or more beds through the one or more beds to the cold end of the one or more beds and through the CHEX when the time-varying magnetic field applied to the one or more beds is low, in order to transfer heat from the CHEX to the HHEX; and

wherein in the second mode of operation, the one or more valves are maintained in a bypass arrangement to allow unidirectional flow of the heat transfer fluid through the HHEX and the CHEX such that heat is transferred from the HHEX to the CHEX, and wherein the heat transfer fluid bypasses the one or more beds while the one or more valves are in the bypass arrangement.

29. The apparatus of claim 28, wherein the time-varying magnetic field applied to the one or more beds is suspended during the second mode.

30. The apparatus of claim 28, further comprising a fan that is configured to direct air over the CHEX.

31. The apparatus of claim 30, wherein the controller is configured to control the fan to direct air over the CHEX during the first mode.

32. The apparatus of claim 30, wherein the controller is configured to control the fan to not direct air over the CHEX during the second mode.

33. The apparatus of claim 28, wherein the controller is configured to control the apparatus to operate in the second mode for a certain amount of time relative to the operation of the first mode.

34. The apparatus of claim 28, wherein the controller is configured to control the apparatus to operate in the second mode when the CHEX reaches a particular temperature.

35. A dual-mode magnetic refrigeration apparatus with bypass, comprising:

one or more beds of magnetocaloric material;

a magnet to apply a time-varying magnetic field to the one or more beds of magnetocaloric material;

a heat transfer fluid;

a pump to circulate the heat transfer fluid;

a hot side heat exchanger (HHEX);

a cold side heat exchanger (CHEX);

one or more valves to direct flow of the heat transfer fluid; and

a controller configured to control periodic switching of the one or more valves to allow the apparatus to operate in a first mode and in a second mode, wherein in the first mode the one or more valves direct the heat transfer fluid to a cold end of the one or more beds through the one or more beds to a hot end of the one or more beds and through the HHEX when the time-varying magnetic field applied to the one or more beds is high, and to the hot end of the one or more beds through the one or more beds to the cold end of the one or more beds and through the CHEX when the time-varying magnetic field applied to the one or more beds is low, in order to transfer heat from the CHEX to the HHEX when an environment of the HHEX is at a similar or higher temperature than an environment of the CHEX; and

wherein in the second mode of operation, the one or more valves are maintained in a bypass arrangement to allow unidirectional flow of the heat transfer fluid through the HHEX and the CHEX such that heat is transferred from the CHEX to the HHEX when an environment of the HHEX is at a lower temperature than an environment of the CHEX, and wherein the heat transfer fluid bypasses the one or more beds while the one or more valves are in the bypass arrangement.

36. The apparatus of claim 35, wherein the time-varying magnetic field applied to the one or more beds is suspended during the second mode.

37. A combination magnetic refrigerator-freezer apparatus, comprising:

a refrigerator compartment that is maintained above 0 C.;

a freezer compartment that is maintained below 0 C.;

a controller;

one or more magnets configured to generate one or more time-varying magnetic fields;

a first magnetic refrigeration system for the refrigerator compartment comprising;

a first set of one or more beds of magnetocaloric material;

a first heat transfer fluid (HTF);

a first pump to drive flow of the first heat transfer fluid;

a hot side heat exchanger (HHEX);

a first cold side heat exchanger (CHEX);

a first section of an inter-stage heat exchanger (IHEX);

one or more first valves to direct flow of the first heat transfer fluid; and

wherein the controller is configured to control the periodic switching of the one or more valves to direct the first HTF to a cold end of the first set of one or more beds through the first set of one or more beds to a hot end of the first set of one or more beds and through the HHEX when the time-varying magnetic field applied to the first set of one or more beds is high, and to the hot end of the first set of one or more beds through the first set of one or more beds to the cold end of the first set of one or more beds and through the first CHEX and the first section of the IHEX when the time-varying magnetic field applied to the first set of one or more beds is low, in order to transfer heat from the first CHEX and the first section of the IHEX to the HHEX; and

a second magnetic refrigeration system for the freezer compartment comprising;

a second set of one or more beds of magnetocaloric material;

a second heat transfer fluid;

a second pump to drive flow of the second heat transfer fluid;

a second CHEX;

a second section of the IHEX;

one or more second valves to direct flow of the second heat transfer fluid; and

wherein the controller is configured to control the periodic switching of the one or more valves to direct the second HTF to a cold end of the second set of one or more beds through the second set of one or more beds to a hot end of the second set of one or more beds and through the second section of the IHEX when the time-varying magnetic field applied to the one or more beds is high, and to the hot end of the second set of one or more beds through the second set of one or more beds to the cold end of the second set of one or more beds and through the second CHEX when the time-varying magnetic field applied to the second set of one or more beds is low, in order to transfer heat from the second CHEX via the second section of the IHEX to the first section of the IHEX.

38. The apparatus of claim 37, wherein the controller controls the one or more first valves to be maintained in a bypass arrangement to allow unidirectional flow of the first heat transfer fluid through the first set of one or more beds, the HHEX, the first CHEX, and the first section of the IHEX, and wherein the controller controls the one or more second valves to be maintained in a bypass arrangement to allow unidirectional flow of the second heat transfer fluid through the second set of one or more beds, the second CHEX, and the second section of the IHEX, such that heat is transferred from the HHEX to the first CHEX and the second CHEX.

39. The apparatus of claim 37, wherein the controller controls the one or more second valves to be maintained in a position to allow unidirectional flow of the second heat transfer fluid through the second set of one or more beds, the second CHEX, and the second section of the IHEX such that heat is transferred from the first CHEX to the second CHEX.

40. The apparatus of claim 37, wherein the second heat transfer fluid has a lower freezing point than the first heat transfer fluid.