US20080314049A1

US20080314049A1 - Active Magnetic Refrigerator

Info

Publication number: US20080314049A1
Application number: US12/180,213
Authority: US
Inventors: Seung Hoon Shin; Dong Kwan Lee
Original assignee: Daewoo Electronics Co Ltd
Current assignee: WiniaDaewoo Co Ltd
Priority date: 2006-01-27
Filing date: 2008-07-25
Publication date: 2008-12-25
Also published as: EP1979690A1; EP1979690A4; WO2007086638A1; JP2009524796A

Abstract

An active magnetic refrigerator includes separated hot and cold heat exchange units wherein a heat transfer fluid that exchanges a heat with a magnetic heat exchange unit having the magnetocaloric material pieces arranged to have a gap therebetween separately circulates through a solenoid valve.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No. PCT/KR2006/004714, filed on Nov. 10, 2006, entitled “Active Magnetic Refrigerator,” which claims priority under 35 U.S.C. §119 to Application No. KR 10-2006-0008730 filed on Jan. 27, 2006, entitled “Active Magnetic Refrigerator,” and Application No. KR 10-2006-0020868 filed on Mar. 6, 2006, entitled “Active Magnetic Refrigerator,” the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an active magnetic refrigerator comprising separated hot and cold heat exchange units wherein a heat transfer fluid that exchanges a heat with a magnetic heat exchange unit having the magnetocaloric material pieces arranged to have a gap therebetween separately circulates through a solenoid valve.

BACKGROUND

A conventional active magnetic refrigerator is disclosed in U.S. Pat. No. 6,826,915. As shown in FIG. 1, (a) a temperature of a magnetic refrigerant material which has a magnetic field applied thereto as a magnet moves to a right increases from a dotted line to a solid line. (b) The temperature of the magnetic refrigerant material drops from the dotted line to the solid line as a heat transfer fluid at a cold side moves to a hot side, and the heat transfer fluid is gradually heated to be hot at a right outlet, thereby emitting heat by an heat exchange with the hot side. (c) The temperature of the magnetic refrigerant material which has a magnetic field erased as the magnet moves to a left decreases more from the dotted line to the solid line. (d) Due to the movement of the heat transfer fluid from the hot side to the cold side, the magnetic refrigerant material is heated from the temperature of the dotted line to that of the solid line, and the heat transfer fluid is relatively cooled to be cold at a left outlet, thereby absorbing heat from the cold side to cool the cold side.
As shown in FIGS. 2 and 3, in accordance with the conventional shuttle type active magnetic regenerator including the above-described cycle, a temperature of the heat transfer fluid heated in a first heat exchange unit 10A in the magnetic field is dropped to an atmospheric temperature by a hot-side heat exchanger 70 and the heat transfer fluid is then passed through the second heat exchange unit 10B. At the same time, since the second heat exchange unit 10B is outside the magnetic field, a magnetic refrigerant material 16 has a low temperature, the temperature of the heat transfer fluid drops while passing through the magnetic refrigerant material layer 16. The heat transfer fluid having the low temperature passes through a cold-side heat exchanger 60 and then enters the first heat exchange unit 10A to be heated. The heat transfer fluid then flows to the hot-side heat exchanger 70, the second heat exchange unit 10B and the cold-side heat exchanger 60 to complete the one cycle.
Contrarily, when the second heat exchange unit 10B is moved to a magnet circuit 22 by a movable mechanism 24, a channel switch 30 reverses the flow of the heat transfer fluid to generate a reverse cycle.
A disadvantage of the conventional shuttle type active magnetic refrigerator is that a single heat transfer fluid circulates two magnetic heat exchange units 10A and 190B to serve as the hot side and the cold side simultaneously such that the heat exchange efficiency is degraded. For instance, when the magnet circuit 22 switched from the first magnetic heat exchange unit 10A to the second magnetic heat exchange unit 10B, the channel switch 30 operates. At the same time, the first magnetic heat exchange unit 10A moves out of the magnetic field so that the temperature of the magnetocaloric material 16 drops rapidly. When the temperature drops, a coolant having the atmospheric temperature that has passed through the hot-side heat exchanger 70 should pass the first magnetic heat exchange unit 10A in order to be effected by the rapidly cooled temperature. However, the heat transfer fluid having a high temperature that has not passed through the hot-side heat exchanger 70 is reversely circulated by the channel switch 30 to be returned to the AMR bed 10. Therefore, the effect of the cooling is hardly obtained.
As shown in FIG. 3, since the magnetic heat exchange unit 10 comprises the inlet/ outlet ports 18 a and 18 b of the heat transfer fluid, the heat transfer fluid having the hot temperature in the magnetic heat exchange unit cannot be exhausted due to the reverse circulation when the channel switch 30 is in operation, thereby degrading the heat exchange efficiency.
In addition, since the conventional active magnetic refrigerator employs the single heat transfer fluid, an amount of the heat transfer fluid passing through the hot side cannot be controlled, and a heat of the magnetocaloric material 16 cannot be cooled promptly, resulting in a degradation of the heat exchange efficiency.
In addition, since a fine mesh 16 is used at the outlet port in order to prevent a problem that the magnetocaloric material 16 of a power type is lost by the heat transfer fluid (coolant), the coolant cannot be circulated smoothly.
Moreover, since the coolant continues to pass the magnetocaloric material 16 at the same spot, a smooth heat exchange is difficult.
In addition, the magnetocaloric material 16 having a microscopic size may be lost when the coolant enters or exits the magnetic heat exchange unit 10.
A conventional rotation magnetic refrigerator is disclosed in U.S. Pat. No. 6,668,560. As shown in FIGS. 4 and 5, in accordance with the conventional rotation magnetic refrigerator, while a heat transfer fluid 17 entering into a cold side inlet port 22 through a cold side inlet port pipe 21 flows to a hot side outlet port 34, the heat transfer fluid 17 absorbs a heat generated by a magnetocaloric effect of a magnetocaloric material 12 having a magnetic field applied thereto and exits to a hot side outlet port pipe 33 through a hot side outlet port ports 34 to cool the magnetocaloric material 12. A hot side sequentially passes the hot side outlet port pipe 33, a valve 71, a pump 60, and a hot heat exchanger 62 and flows into a magnetic heat exchange compartment 13. In a hot side inlet port pipe 31, the hot side is divided into the hot side inlet port pipe 31 and a cold side outlet port 23, and meets a cold side at a cold side outlet port pipe 24 and proceed to a valve 74. When the hot side moves from a hot side inlet port 32 to the cold side outlet port pipe 24, the hot side is cooled by passing the magnetocaloric material 12 already cooled by the hot side. The cold side that has passed through the valve 74 passes a cold heat exchanger 63 and flows to pipes 83 and 21 to repeat a cycle (a detailed description is omitted. See U.S. Pat. No. 6,668,560 for omitted reference numerals).
As described above, since the conventional rotation magnetic refrigerator comprises twelve magnetic heat exchange compartments, four valves 71, 72, 73 and 74 and more than 24 pipes, it is difficult to manufacture the conventional magnetic refrigerator.
Moreover, since the single heat transfer fluid is circulated to serve as the hot side and the cold side simultaneously. As shown in FIG. 5, the heat transfer fluid enters the hot-side through the hot side inlet port 32 and cooled by passing through the cooled the magnetocaloric material to exit through the cold side inlet port 24 resulting in the degradation of the heat exchange efficiency. At this time, when the heat transfer fluid having a temperature lower than that of the hot side injected into the hot side inlet port 32 enters the hot side inlet port 32 and passes through the cooled magnetocaloric material, the heat transfer fluid having a lower temperature may be obtained at the cold side inlet port 24 resulting in an improvement of the heat exchange efficiency.
In addition, since the conventional active magnetic refrigerator employs the single heat transfer fluid, the amount of the heat transfer fluid passing through the hot side cannot be controlled, and a heat of the magnetocaloric material cannot be cooled promptly, resulting in a degradation of the heat exchange efficiency.

SUMMARY

It is an object of the present invention to provide an active magnetic refrigerator wherein a hot side and a cold side is dividedly circulated to provide a high heat exchange efficiency and to control an mount of the heat transfer fluid.
In order to achieve the above-described object, there is provided an active magnetic refrigerator, comprising: first and second heat exchange units including a magnetocaloric material for passing a flow of a heat transfer fluid; a magnet unit for applying a magnetic field to one of the first heat exchange unit and the second heat exchange unit or erasing the magnetic field from the first heat exchange unit or the second heat exchange unit; a hot heat exchanger for coupled to the first heat exchange unit and the second heat exchange unit for a circulation; a cold heat exchanger for coupled to the first heat exchange unit and the second heat exchange unit for the circulation; a first solenoid valve for directing a first heat transfer fluid exhausted from the hot heart exchanger to one of the first heat exchange unit and the second heat exchange unit having the magnetic field applied thereto; and a second solenoid valve for directing a second heat transfer fluid exhausted from the cold heart exchanger to one of the second heat exchange unit and the first heat exchange unit having the magnetic field erased therefrom.
In accordance with the refrigerator, a hot side and a cold side is dividedly circulated to provide a high heat exchange efficiency and to control an amount of the heat transfer fluid.
It is preferable that the magnet unit comprises a first electromagnet attached to the first heat exchange unit, and a second electromagnet attached to the second heat exchange unit.
In addition, when the magnet unit comprises a permanent magnet and a permanent magnet conveying member for moving the permanent magnet to one of the first heat exchange unit and the second heat exchange unit, a use of the plurality of the magnetic heat exchange units is possible with a single magnet unit.
It is preferable that the permanent magnet conveying member comprises a yoke having the permanent magnet disposed at both sides thereof, and a reciprocation transfer member for reciprocating of the yoke, wherein The refrigerator in accordance with claim 4, wherein the reciprocation transfer member comprises a rack attached to the yoke, a pinion engaged with the rack, and a motor for transferring a rotational power to the pinion.
On the other hand, it is preferable that the magnet unit comprises a magnet and a magnet rotating assembly for rotating the magnet, and the refrigerator further comprises a plurality of mounting parts for mounting the first heat exchange unit and the second heat exchange unit, the mounting part being disposed on a rotational plane of the magnet, a through-hole having the magnet rotating assembly mounted at a center thereof, and a table for constituting a connecting path for connecting the heat exchangers and the magnetic heat exchange units.
It is preferable that the connecting path of a portion at a crossing of the first heat transfer fluid and the second heat transfer fluid comprises a tunnel and a bridge.
It is also preferable that the magnet rotating assembly comprises a flange supporting the magnet disposed upper and lower sides of one of the first heat exchange unit and the second heat exchange unit, a yoke consisting of a web connecting the flange, and a rotational power transfer member for transferring a rotational power to the yoke.
When the first heat exchange unit comprises a first case including the magnetocaloric material, an upper inlet port and an upper outlet port disposed on an upper surface of the first case, and an lower inlet port and an lower outlet port disposed on an lower surface of the first case, and the second heat exchange unit comprises a second case including the magnetocaloric material, an upper inlet port and an upper outlet port disposed on an upper surface of the second case, and an lower inlet port and an lower outlet port disposed on an lower surface of the second case, the cold side and the hot side is completely divided as to improve the heat exchange efficiency.
It is preferable that the magnetocaloric material comprises a plurality of magnetocaloric material pieces disposed in the first case or the second case, the plurality of magnetocaloric material pieces have a gap therebetween so that a mesh may not be used for a smooth flow of the heat transfer fluid.
It is preferable that each of the plurality of magnetocaloric material pieces comprises a gadolinium plate or a gadolinium rod having a constant circular cross-section in the lengthwise direction.
When the gadolinium rod comprises a groove in the lengthwise direction, a contact area is increased more resulting in an improvement of the heat exchange efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a concept of an active magnetic refrigerator.

FIG. 2 is a diagram illustrating a configuration of a conventional active magnetic refrigerator.

FIG. 3 is a cross-sectional view illustrating a magnetic heat exchange unit for the active magnetic refrigerator of FIG. 2.

FIG. 4 is a plan view illustrating a heat transfer fluid in another conventional active magnetic refrigerator.

FIG. 5 is a plan view exemplifying a magnetic heat exchange unit including a magnetocaloric material of a powder type of FIG. 4.

FIG. 6 is a configuration diagram illustrating a magnetic refrigerator in accordance with a first preferred embodiment of the present invention.

FIG. 7 is a plan view illustrating a magnet unit for the active magnetic refrigerator of FIG. 6.

FIG. 8 is a perspective view illustrating an exterior of the magnetic heat exchange unit for the active magnetic refrigerator of FIG. 6.

FIG. 9 is a cross-sectional view of the magnetic heat exchange unit in accordance with the first preferred embodiment of the present invention taken along a line B-B of FIG. 8.

FIGS. 10 through 12 are cross-sectional views of the magnetic heat exchange unit in accordance with another alternative example taken along a line B-B of FIG. 8.

FIG. 13 is a perspective view illustrating a magnetocaloric material having a shape of a rod having a groove in a lengthwise direction.

FIGS. 14 and 15 are plan views illustrating a cycle of a heat transfer fluid according to a position of a magnet in accordance with an active magnetic refrigerator in accordance with a second preferred embodiment of the present invention.

FIG. 16 is a plan view illustrating the cycle of FIGS. 14 and 15 as one.

FIG. 17 is a schematic diagram illustrating a magnet rotating assembly.

FIGS. 18 and 19 are a perspective view and a partially magnified view of a table having a flow path.

DETAILED DESCRIPTION

The above-described objects and other objects and characteristics and advantages of the present invention will now be described in detail with reference to the accompanied drawings.

First Embodiment

FIG. 6 is a configuration diagram illustrating a magnetic refrigerator in accordance with a first preferred embodiment of the present invention, FIG. 7 is a plan view illustrating a magnet unit for the active magnetic refrigerator of FIG. 6, and FIG. 8 is a perspective view illustrating an exterior of the magnetic heat exchange unit for the active magnetic refrigerator of FIG. 6.
As shown in FIGS. 6 through 8, the active magnetic refrigerator in accordance with the preferred embodiment of the present invention comprises a first magnetic heat exchange unit 113A and a second magnetic heat exchange unit 113B including a magnetocaloric material, a magnet unit 140 for applying a magnetic field to the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B or erasing the magnetic field therefrom, a hot heat exchanger 162, a cold heat exchanger 163, a first solenoid valve 120 a and a second solenoid valve 120 b.
The heat transfer fluid is divided into a first heat transfer fluids 17 aa and 17 ab circulating in the hot heat exchanger 162, and a second heat transfer fluids 17 bb and 17 bc circulating in the cold heat exchanger 163 to form a cycle.
The first solenoid valve 120 a is a 3-port 2-way solenoid valve for redirecting the first heat transfer fluid 17 aa of a cold side flowing in a tube 130 of the hot heat exchanger 162 to a tube 131 a through the first magnetic heat exchange unit 113A or to a tube 131 b through the second magnetic heat exchange unit 113B such that the first heat transfer fluid 17 aa flows in a tube 131.
That is, the first solenoid valve 120 a is disposed at a junction wherein the tube 130 is divided into tubes 130 a and 130 b connected to the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B.
Similarly, the second solenoid valve 120 b is the 3-port 2-way solenoid valve for redirecting the second heat transfer fluid 17 bc of a hot side flowing in a tube 132 of the cold heat exchanger 163 to a tube 133 a through the second magnetic heat exchange unit 113B or to a tube 133 b through the first magnetic heat exchange unit 113A such that the second heat transfer fluid 17 bc flows in a tube 133.
That is, the second solenoid valve 120 b is disposed at a junction wherein the tube 132 is divided into tubes 132 a and 132 b connected to the second magnetic heat exchange unit 113B and the first magnetic heat exchange unit 113A.
As described above, since the first heat transfer fluids 17 aa and 17 ab of the hot side and the second heat transfer fluids 17 bb and 17 bc of the cold side is dividedly circulated as two cycles, a larger amount of the heat transfer fluid may be flown to the hot side by controlling an amount thereof to improve a heat exchange efficiency.
Moreover, it is preferable that the flow of the first heat transfer fluids 17 aa and 17 ab and the second heat transfer fluids 17 bb and 17 bc is generated by pumps 160 and 161.
That is, as shown in FIG. 6, the hot heat exchange circulating member and the cold heat exchange circulating member embodies a closed cycle similar to a closed circuit. Therefore, since an atmospheric pressure does not act on the heat transfer fluid directly, almost no resistance is applied to the pumps 160 and 161, thereby reducing a time required for the heat exchange and improving the heat exchange efficiency.
The first magnetic heat exchange units 113A and 113B includes a magnetocaloric material 112 for passing the flow of the heat transfer fluid. The magnetocaloric material 112 comprises a gadolinium (Gd) of a fine powder type. The gadolinium has pores having a high osmosis to the flow of the heat transfer fluid, and a superior absorption and emission of a heat.

First Alternative Example

Magnetic Heat Exchange Unit 113

As shown in FIGS. 8 and 9, a magnetic heat exchange unit 113 of the first alternative example a case 115 extending vertically, and a plurality of magnetocaloric material pieces 112 disposed in the case 115 to form a gap 114 therebetween.
Ports 115 a and 116 b are disposed on a top surface of the case 115, and ports 115 b and 116 a are disposed on a bottom surface of the case 115.
When the case 115 is the first magnetic heat exchange unit 113A, the ports 115 a and 116 b are connected to the tubes 130 a and 133 b, and the ports 115 b and 116 a are connected to the tubes 131 a and 132 b.
When the case 115 is the second magnetic heat exchange unit 113B, the ports 115 a and 116 b are connected to the tubes 130 b and 133 a, and the ports 115 b and 116 a are connected to the tubes 131 b and 132 a.
The case 115 may be manufactured by arranging and mounting the plurality of magnetocaloric material pieces 112 while the case 115 is disassembled in two parts, and then assembling, bonding or welding the parts.
The case 115 in accordance with the embodiment may be connected to the tube by the ports 115 a and 116 b and the ports 115 b and 116 a to be supported. The support improves the heat exchange efficiency by establishing an adiabatic state wherein the plurality of magnetocaloric material pieces 112 of the magnetic heat exchange unit 113 is not exposed.
The magnetocaloric material 112, which have a shape of a plate manufactured from a gadolinium powder, are disposed in the case 115 in parallel such that the gap 114 prevents a contact therebetween. The plurality of magnetocaloric material pieces 112 of the gadolinium plate may be a thin foil or a thick sheet according to a flow velocity and a heat exchange rate of the heat transfer fluid.
As described above, the plurality of magnetocaloric material pieces 112 having the gap 114 therebetween prevents the loss of the material even when a mesh is not used, a contact with the entirety of the plurality of magnetocaloric material pieces 112 as well as a smooth flow is obtained since the heat transfer fluid flows through the gap 114, and a higher heat exchange rate compared to that of the conventional art is obtained since a contact area is larger in case of the gadolinium plate.

Second Alternative Example

Magnetic Heat Exchange Unit 213

As shown in FIG. 10, the magnetic heat exchange unit 213 in accordance with the second alternative example comprises a plurality of magnetocaloric material pieces 212 having a shape of a rod instead of the plurality of magnetocaloric material pieces 112 having the shape of the plate. That is, each of the plurality of magnetocaloric material pieces 212 has the shape of the rod having a constant circular cross-section in the lengthwise direction.
A gap 214 between the plurality of magnetocaloric material pieces 212 having the shape of the rod is formed when in contact or not in contact due to the circular cross-section even when the plurality of magnetocaloric material pieces 212 are randomly arranged such that an effect of the first alternative example is obtained when the heat transfer fluid flows through the gap 214.
It is preferable that the plurality of magnetocaloric material pieces 212 having the shape of the rod arranged vertically are tied as one to be inserted in a batch.
On the other hand, as shown in FIG. 13, it is preferable that the plurality of magnetocaloric material pieces 212 having the shape of the rod comprises a groove 212 a in a lengthwise direction to increase the contact area with the heat transfer fluid, thereby improving the heat exchange efficiency.

Third Alternative Example

Magnetic Heat Exchange Unit 313

As shown in FIG. 11, the magnetic heat exchange unit 313 in accordance with the third alternative example comprises a plurality of magnetocaloric material pieces 312 having the shape of the rod arranged to have a gap 314 therebetween similar to the plurality of magnetocaloric material pieces 112 having the shape of the plate of the first alternative example instead of a random arrangement of the plurality of magnetocaloric material pieces 212 having the shape of the rod of the second alternative example.
It is preferable that the plurality of magnetocaloric material pieces 312 having the shape of the rod arranged vertically are tied as one to be inserted in a batch.
As shown in FIG. 13, it is preferable that the plurality of magnetocaloric material pieces 312 having the shape of the rod comprises the groove 212 a in the lengthwise direction.

Fourth Alternative Example

Magnetic Heat Exchange Unit 413

As shown in FIG. 12, the magnetic heat exchange unit 413 in accordance with the fourth alternative example comprises a magnetocaloric material piece 412 a having the shape of the rod and a magnetocaloric material piece 412 b having the shape of the plate combined to have a gap 414 therebetween.
The magnet unit 140 may be attached to the magnetic heat exchange unit 113.
Similar to the first embodiment, the magnet unit 140 may comprise a permanent magnet 141 disposed at both sides of the first magnetic heat exchange unit 113A or the second magnetic heat exchange unit 113B, and a permanent magnet conveying member for moving the permanent magnet 141 between the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B, or may comprises an electromagnet (not shown) attached to the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B to apply or erase the magnetic field. In addition, the magnet unit that is pushed toward or pulled away from (vertical to a paper surface of FIG. 7) the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B may be embodied.
As shown in FIG. 7, the permanent magnet conveying member comprises a yoke 143 having the permanent magnet 141 disposed at both sides thereof, and a reciprocation transfer member for carrying out a reciprocation of the yoke 143.
The yoke 143 serves to concentrate the magnetic field of the permanent magnet 141 in a direction of the magnetic heat exchange unit 113 so that the magnetic field having a higher intensity is applied to the magnetic heat exchange unit.
The reciprocation transfer member may be embodied with a rack 145 attached to the yoke 143, a pinion 147 engaged with the rack 145, and a motor 149 a shaft of which transfers a rotational power to the pinion 147. The rack 145 may be embodied by forming a tooth on a rod of a link of the yoke 143 or welding a separate rack to the rod.
It will be understood by those skilled in the art that various reciprocation transfer members that convert a rotational motion to a linear motion may be used in accordance with the present invention.
While FIG. 6 illustrates a case wherein the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B are disposed in parallel in order to show an entirety of the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B, it is preferable that the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B is disposed in line.
When the electromagnet is used, a current may be applied intermittently to embody applying or erasing the magnetic field.
The cycle of the active magnetic refrigerator employing the magnetic heat exchange unit 113 in accordance with the first alternative example of the present invention will now be described wherein the characteristic of the magnetocaloric material is subjected to an experiment by setting an atmospheric temperature which carries out an heat exchange with the hot heat exchanger 162, and an atmospheric temperature which carries out an heat exchange with the cold heat exchanger 163 are set at 26° C. respectively, considering a characteristic of the magnetocaloric material wherein a temperature thereof rises by 3° C. when the magnetocaloric material is magnetized and drops by 3° C. when cooled by the heat transfer fluid.
The entire system except the magnet unit 140 is fixed and the magnet unit 140 is subjected to the reciprocation motion between the first magnetic heat exchange unit 113A and the second magnetic heat exchange unit 113B to alternately apply and erase the magnetic field.
A state wherein the magnet unit 140 is positioned at the first magnetic heat exchange unit 113A is be described below.
When the magnetic field is applied to the magnetocaloric material of the first magnetic heat exchange unit 113A, the first solenoid valve 120 a is in operation to carry out a heat exchange wherein the first heat transfer fluid 17 aa of the tube 130 (26° C.) is flown to the first magnetic heat exchange unit 113A through the tube 130 a with a pressure to cool the magnetocaloric material (29° C.) heated by the magnetic field to 26° C., and the first heat transfer fluid 17 ab absorbs a heat to have a temperature of 29° C. A cycle is carried out wherein the first heat transfer fluid 17 ab that carried out the heat exchange passes through the tube 131 a and the tube 131 to carry out an heat exchange with an atmosphere at the hot heat exchanger 162 and cooled to the first heat transfer fluid 17 aa of 26° C. (see thin solid line of FIG. 6).
The second solenoid valve 120 b at the second magnetic heat exchange unit 113B that does not have any magnetic field applied thereto is operated to carry out an heat exchange wherein the second heat transfer fluid 17 bc (26° C.) of the tube 132 is flown to the second magnetic heat exchange unit 113B with a pressure through the tube 132 a so as to heat the heat transfer fluid (23° C.) to 26° C., and the second heat transfer fluid 17 bc is cooled to 23° C. After the second heat transfer fluid 17 bb of 23° C. that carried out the heat exchange passes through the tube 133 a and the tube 133 to carry out an heat exchange with an indoor at the cold heat exchanger 163, the second heat transfer fluid 17 bc of 23° C. passes through the second magnetic heat exchange unit 113B. The above-described cycle is repeated to carry out the heat exchange (see thick solid line of FIG. 6).
As described above, while the first solenoid valve 120 a is a valve for redirecting the first heat transfer fluid to the first magnetic heat exchange unit 113A or the second magnetic heat exchange unit 113B so that the first heat transfer fluid may absorb the heat in the indoor and then emit the heat to the atmosphere, the second solenoid valve 120 bis a valve for redirecting the second heat transfer fluid to the first magnetic heat exchange unit 113A or the second magnetic heat exchange unit 113B that does not have the magnetic field applied thereto so that the second heat transfer fluid 17 may be cooled and then may absorb the hear in the indoor. The redirecting function may be embodied by a simple program in a digital format.
As described above, the circulation of the heat transfer fluid is divided into the hot heat exchanger and the cold heat exchanger for the heat exchange of two cycles, thereby simplifying the structure of a magnetic refrigerating cycle.
In addition, in accordance with the system, since the heat transfer fluid at the atmospheric temperature is injected to the magnetocaloric material, the heat transfer fluid is heated and cooled more according to a state of the material to improve an efficiency of the heat exchanger.
Moreover, since the active magnetic refrigerator is divided into the hot heat exchanger and the cold heat exchanger, amounts of the first heat transfer fluid and the second heat transfer fluid 17 bb are controlled to be different. Therefore, a larger amount of the first heat transfer fluid may be flown to the hot side of the magnetic heat exchange unit to maximize the cooling of the magnetocaloric material.

Second Embodiment

FIGS. 14 and 15 are plan views illustrating a cycle of a heat transfer fluid according to a position of a magnet in accordance with an active magnetic refrigerator in accordance with a second preferred embodiment of the present invention, FIG. 16 is a plan view illustrating the cycle of FIGS. 14 and 15 as one, FIG. 17 is a schematic diagram illustrating a magnet rotating assembly, and FIGS. 18 and 19 are a perspective view and a partially magnified view of a table having a flow path.
As shown in FIGS. 14 through 19, the active magnetic refrigerator in accordance with the preferred embodiment of the present invention comprises a first magnetic heat exchange units 113A and 113A′ and a second magnetic heat exchange units 113B and 113B′ including a magnetocaloric material, a magnet 1141 attached to the magnetic heat exchange units 113A, 113A′, 113B and 113B′, a magnet rotating assembly 1140 for applying and erasing a magnetic field by rotating the magnet 1141, a hot heat exchanger 162, a cold heat exchanger 163, a first solenoid valve 120 a and a second solenoid valve 120 b.
The heat transfer fluid is divided into a first heat transfer fluids 17 aa and 17 ab circulating in the hot heat exchanger 162, and a second heat transfer fluids 17 bb and 17 bc circulating in the cold heat exchanger 163 to form a cycle.
A plurality of the first magnetic heat exchange units 113A and 113A′ are disposed on a left and a right and a plurality of the second magnetic heat exchange units 113B and 113B′ are disposed at a top and a bottom from a plan view.
The first solenoid valve 120 a is a 3-port 2-way solenoid valve for redirecting the first heat transfer fluid 17 aa of the cold side exhausted from the hot heat exchanger 162 to the first magnetic heat exchange units 113A and 113A′ through the tube 130 a or to the second magnetic heat exchange units 113B and 133B′ through the tube 130 b such that the first heat transfer fluid 17 ab that has carried out a heat exchange flows into the cold heat exchanger 163.
That is, the first solenoid valve 120 a is disposed at a junction wherein the tube 130 a or the tube 130 b connected to the first magnetic heat exchange unit 113A or the second magnetic heat exchange unit 113B is divided.
Similarly, the second solenoid valve 120 b is the 3-port 2-way solenoid valve for redirecting the second heat transfer fluid 17 bb of the hot side exhausted from the cold heat exchanger 163 to the second magnetic heat exchange units 113B and 113B′ through the tube 132 a or to the second magnetic heat exchange units 113B and 133B′ through the tube 130 b such that the first heat transfer fluid 17 ab that has carried out a heat exchange flows into the cold heat exchanger 163.
That is, the second solenoid valve 120 b is disposed at a junction wherein the tube 132 a or the tube 132 b connected to the second magnetic heat exchange unit 113B′ or the first magnetic heat exchange unit 113A′ is divided.
As described above, since the first heat transfer fluids 17 aa and 17 ab of the hot side and the second heat transfer fluids 17 bb and 17 bc of the cold side is dividedly circulated as two cycles, a larger amount of the heat transfer fluid may be flown to the hot side by controlling an amount thereof to improve a heat exchange efficiency.
Since the magnetic heat exchange units 113A, 113A′, 113B and 113B′ are similar to those of the first embodiment, a detailed description is thereby omitted.
In addition, it is preferable that the magnetic heat exchange units 113A, 113A′, 113B and 113B′ are mounted on a table 1150. As shown in FIG. 18, the table 1150 comprises an upper plate 1150 a having mounting parts 1153A, 1153A′, 1153B and 1153B′ formed therein for mounting the magnetic heat exchange units 113A, 113A′, 113B and 113B′ having a predetermined distance therebetween, and a connecting path for connecting the tubes 130 a, 131 a, 132 a, 133 a, 130 b, 131 b, 132 b and 133 b and the upper plate 1150 a as well as supporting the upper plate 1150 a. The mounting parts 1153A and 1153B may be embodied by a groove or a through-hole.
Particularly, as shown in FIG. 19, a mixing of the first heat transfer fluid and the second heat transfer fluid is prevented at a crossing thereof by employing a bridge 1155 and a tunnel 1157 in the connecting path inside the upper plate 1150 a. The bridge 1155 has a form of elevated overpass which is thicker than other connecting path to allow a facile formation of the tunnel 1157.
Due to the bridge 1155 and the tunnel 1157, a thickness of the upper plate 1150 a is minimized.
The magnet rotating assembly 1140 for applying the magnetic field to the first magnetic heat exchange units 113A and 113A′ or the second magnetic heat exchange units 113B and 113B′ or erasing the magnetic field therefrom by rotating the magnet 1141 may be mounted on a through-hole 1151 punched at a center of the upper plate 1150 a.
The magnet rotating assembly 1140 rotates the magnet 1141 disposed at both sides of the first magnetic heat exchange units 113A and 113A′ or the second magnetic heat exchange units 113B and 113B′ to the second magnetic heat exchange units 113B and 113B′ or the first magnetic heat exchange units 113A and 113A′. That is, as shown in FIG. 17, it is preferable that the magnet rotating assembly 1140 comprises a plurality of yokes 1143 having the magnet 1141 disposed at both sides thereof, a rotation support 1147 for supporting the magnet 1141, and a rotational power transfer member for rotating the rotation support 1147.
The rotational power transfer member may be embodied by a motor 1148, a rotating shaft 1149 for transferring a rotational power of the motor 1148 to the rotation support 1147.
It should be understood by the skilled in the art that various rotational power transfer members may be embodied such as directly connecting the rotating shaft 1149 to the plurality of yokes 1143 for a rotation or using a belt to rotate the plurality of yokes 1143.
The cycle of the active magnetic refrigerator employing the magnetic heat exchange units 113A, 113A′, 113B and 113B′ in accordance with the second embodiment of the present invention will now be described wherein the characteristic of the magnetocaloric material is subjected to an experiment by setting an atmospheric temperature which carries out an heat exchange with the hot heat exchanger 162, and an atmospheric temperature which carries out an heat exchange with the cold heat exchanger 163 are set at 26° C. respectively, considering a characteristic of the magnetocaloric material wherein a temperature thereof rises by 3° C. when the magnetocaloric material is magnetized and drops by 3° C. when cooled by the heat transfer fluid.
The entire system except the magnet 1141 is fixed and only the magnet 1141 is rotated by the magnet rotating assembly 1140 to alternately apply the magnetic field to the magnetocaloric material of the first magnetic heat exchange units 113A and 113A′ or the second magnetic heat exchange units 113B and 113B′.
As shown in FIG. 14, a state wherein the magnet 1141 is positioned at the first magnetic heat exchange units 113A and 113A′ at the right and left thereof is be described below.
When the magnetic field is applied to the magnetocaloric material of the first magnetic heat exchange units 113A and 113A′, the first solenoid valve 120 a is in operation to carry out a heat exchange wherein the first heat transfer fluid 17 aa of 26° C. is flown to the first magnetic heat exchange units 113A and 113A′ through the tube 130 a with a pressure to cool the magnetocaloric material (29° C.) heated by the magnetic field to 26° C., and the first heat transfer fluid 17 ab absorbs a heat to have a temperature of 29° C. A cycle is carried out wherein the first heat transfer fluid 17 ab that carried out the heat exchange passes through the tube 131 a to carry out an heat exchange with an atmosphere at the hot heat exchanger 162 and cooled to the first heat transfer fluid 17 aa of 26° C. (see thin solid line arrow of FIGS. 14 and 15).
The second solenoid valve 120 b at the second magnetic heat exchange units 113B and 113B′ that do not have any magnetic field applied thereto is operated to carry out an heat exchange wherein the second heat transfer fluid 17 bb having the temperature of 26° C. is flown to the second magnetic heat exchange units 113B and 113B′ with a pressure through the tube 132 a so as to heat the heat transfer fluid having the temperature of 23° C. to 26° C., and the second heat transfer fluid 17 bc is cooled to 23° C. After the second heat transfer fluid 17 bc of 23° C. that carried out the heat exchange passes through the tube 133 a to carry out an heat exchange with the indoor at the cold heat exchanger 163, the second heat transfer fluid 17 bb passes through the second magnetic heat exchange units 113B. The above-described cycle is repeated to carry out the heat exchange (see thick solid line arrow of FIGS. 14 and 15).
On the other hand, as shown in FIG. 15, a state wherein the magnet 1141 is rotated to be positioned at the second magnetic heat exchange units 113B and 113B′ at the top and the bottom is described below.
When the magnetic field is applied to the magnetocaloric material of the second magnetic heat exchange units 113B and 113B′, the first solenoid valve 120 a is in operation to carry out a heat exchange wherein the first heat transfer fluid 17 aa of 26° C. is flown to the second magnetic heat exchange units 113B and 113B′ through the tube 130 b with a pressure to cool the magnetocaloric material (29° C.) heated by the magnetic field to 26° C., and the first heat transfer fluid 17 ab absorbs a heat to have a temperature of 29° C. A cycle is carried out wherein the first heat transfer fluid 17 ab that carried out the heat exchange passes through the tube 131 b to carry out an heat exchange with an atmosphere at the hot heat exchanger 162 and cooled to the first heat transfer fluid 17 aa of 26° C. (see thin dotted line arrow of FIGS. 14 and 16).
The second solenoid valve 120 b at the first magnetic heat exchange units 113A and 113A′ that do not have any magnetic field applied thereto is operated to carry out an heat exchange wherein the second heat transfer fluid 17 bb having the temperature of 26° C. is flown to the first magnetic heat exchange units 113A and 113A′ with a pressure through the tube 132 b so as to heat the heat transfer fluid having the temperature of 23° C. to 26° C., and the second heat transfer fluid 17 bc is cooled to 23° C. After the second heat transfer fluid 17 bc of 23° C. that carried out the heat exchange passes through the tube 133 b to carry out an heat exchange with the indoor at the cold heat exchanger 163, the second heat transfer fluid 17 bb of 23° C. passes through the first magnetic heat exchange units 113A and 113A′. the above-described cycle is repeated to carry out the heat exchange (see thick dotted line of FIGS. 14 and 16).
As described above, while the first solenoid valve 120 a is a valve for redirecting the first heat transfer fluid to the first magnetic heat exchange units 113A and 113A′ or the second magnetic heat exchange units 113B and 113B′ so that the first heat transfer fluid may absorb the heat in the indoor and then emit the heat to the atmosphere, the second solenoid valve 120 bis a valve for redirecting the second heat transfer fluid to the first magnetic heat exchange units 113A and 113A′ or the second magnetic heat exchange units 113B and 113B′ that do not have the magnetic field applied thereto so that the second heat transfer fluid may be cooled and then may absorb the hear in the indoor. The redirecting function may be embodied by a simple program in a digital format.
As described above, the circulation of the heat transfer fluid is divided into the hot heat exchanger and the cold heat exchanger for the heat exchange of two cycles, thereby simplifying the structure of a magnetic refrigerating cycle.
While the present invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims.
As described above, the circulation of the heat transfer fluid is divided into the hot heat exchanger and the cold heat exchanger for the heat exchange of two cycles, thereby simplifying the structure of a magnetic refrigerating cycle.
Moreover, since the magnetic refrigerator is divided into the hot heat exchanger and the cold heat exchanger, amounts of the first heat transfer fluid and the second heat transfer fluid 17 bb are controlled to be different. Therefore, a larger amount of the first heat transfer fluid may be flown to the hot side of the magnetic heat exchange unit to maximize the cooling of the magnetocaloric material.
In addition, the adiabatic state wherein the magnetocaloric material piece is not exposed may be achieved to improve the heat exchange efficiency.
Moreover, the hot heat exchange circulating member and the cold heat exchange circulating member embodies the close cycle similar to the closed circuit. Therefore, since the atmospheric pressure does not act on the heat transfer fluid directly, almost no resistance is applied to the pump, thereby reducing the time required for the heat exchange and improving the heat efficiency. This allows a use of a single pump since the pressure adjustment range is increased according to a size and the heat efficiency of the magnetic heat exchange unit.
In addition, each of the hot side and the cold side has dedicated ports (two in the upper portion, two in the lower portion), the hot and cold heat transfer fluids are not mixed resulting in the high heat exchange efficiency.
The magnetic heat exchange unit is constructed to comprise the case and the plurality of magnetocaloric material pieces disposed in the case to form the gap so that the heat transfer fluid may be flown through the gap, thereby improving the heat exchange efficiency through a uniform contact between the plurality of magnetocaloric material pieces and the heat transfer fluid and eliminating a need for the mesh for the smooth flow of the heat transfer fluid.
Moreover, the magnetocaloric material piece is embodied to have the shape of the plate or the rod, the magnetocaloric material piece is not easily lost.
In addition, since the magnet unit comprises the yoke and the reciprocation transfer member, the magnetic field may be applied or erased with the magnetic heat exchange unit being fixed, and the yoke concentrates the magnetic field of the permanent magnet toward the direction of the magnetic heat exchange unit to apply the high intensity magnetic field to the magnetic heat exchange unit
Moreover, the heat exchange efficiency is improved by increasing the contact area with the heat transfer fluid when the groove is formed on the plurality of magnetocaloric material pieces having the shape of the rod in the lengthwise direction.
In addition, the active magnetic refrigerator comprises the table which includes a plurality of mounting parts for mounting the first magnetic heat exchange unit and the second magnetic heat exchange unit disposed on the rotational plane of the magnet, a through-hole having the magnet rotating assembly mounted at the center thereof, and a table for constituting a connecting path for connecting the heat exchangers and the magnetic heat exchange units such that an installation of the magnetic heat exchange unit is simplified, the formation of the connecting path for connecting the heat exchanges is possible, and a layout of the tube is superior.
Moreover, since the connecting path at a crossing of the first heat transfer fluid and the second heat transfer fluid has the form of the tunnel and the bridge, the mixing of the fluids is prevented while maintaining the superior layout of the tube.
In addition, since the magnet rotating assembly comprises the yoke and the rotational power transfer member, the magnetic field may be applied or erased while the magnetic heat exchange unit being fixed, and the yoke concentrates the magnetic field of the magnet toward the direction of the magnetic heat exchange unit to apply the high intensity magnetic field to the magnetic heat exchange unit.

LIST OF REFERENCE SIGNS

- 160, 161: pump
- 162: hot heat exchanger
- 163: cold heat exchanger
- 17 aa, 17 ab: first heat transfer fluids
- 17 bb, 17 bc: second heat transfer fluids
- 112, 212, 312, 412 a, 412 b: magnetocaloric material pieces (Gd)
- 113, 213, 313, 413: magnetic heat exchange units
- 114, 214, 314, 414: gaps
- 115: case
- 115 a, 115 b′: outlet ports
- 115 a′, 115 b: inlet ports
- 130, 131, 132, 133: tube
- 140: magnet unit
- 141: permanent magnet
- 143: yoke
- 145: rack
- 147: pinion
- 149: motor shaft
- 1140: magnet rotating assembly
- 1141: magnet
- 1143: yoke
- 1147: rotation support.
- 1148: motor
- 1149: motor shaft
- 1150: table
- 1150 a: upper plate
- 1150 b: leg
- 1153A, 1153B: mounting part
- 1155: bridge
- 1157: tunnel

Claims

1. An active magnetic refrigerator, comprising:

first and second heat exchange units including a magnetocaloric material for passing a flow of a heat transfer fluid;

a magnet unit for applying a magnetic field to one of the first heat exchange unit and the second heat exchange unit or erasing the magnetic field from the first heat exchange unit or the second heat exchange unit;

a hot heat exchanger for coupled to the first heat exchange unit and the second heat exchange unit for a circulation;

a cold heat exchanger for coupled to the first heat exchange unit and the second heat exchange unit for the circulation;

a first solenoid valve for directing a first heat transfer fluid exhausted from the hot heart exchanger to one of the first heat exchange unit and the second heat exchange unit having the magnetic field applied thereto; and

a second solenoid valve for directing a second heat transfer fluid exhausted from the cold heart exchanger to one of the second heat exchange unit and the first heat exchange unit having the magnetic field erased therefrom.

2. The refrigerator in accordance with claim 1, wherein the magnet unit comprises a first electromagnet attached to the first heat exchange unit, and a second electromagnet attached to the second heat exchange unit.

3. The refrigerator in accordance with claim 1, wherein the magnet unit comprises a permanent magnet and a permanent magnet conveying member for moving the permanent magnet to one of the first heat exchange unit and the second heat exchange unit.

4. The refrigerator in accordance with claim 3, wherein the permanent magnet conveying member comprises a yoke having the permanent magnet disposed at both sides thereof, and a reciprocation transfer member for reciprocating of the yoke.

5. The refrigerator in accordance with claim 4, wherein the reciprocation transfer member comprises a rack attached to the yoke, a pinion engaged with the rack, and a motor for transferring a rotational power to the pinion.

6. The refrigerator in accordance with claim 1, wherein the magnet unit comprises a magnet and a magnet rotating assembly for rotating the magnet, and

further comprising a plurality of mounting parts for mounting the first heat exchange unit and the second heat exchange unit, the mounting part being disposed on a rotational plane of the magnet, a through-hole having the magnet rotating assembly mounted at a center thereof, and a table for constituting a connecting path for connecting the heat exchangers and the magnetic heat exchange units.

7. The refrigerator in accordance with claim 6, wherein the connecting path of a portion at a crossing of the first heat transfer fluid and the second heat transfer fluid comprises a tunnel and a bridge.

8. The refrigerator in accordance with claim 7, wherein the magnet rotating assembly comprises a flange supporting the magnet disposed upper and lower sides of one of the first heat exchange unit and the second heat exchange unit, a yoke consisting of a web connecting the flange, and a rotational power transfer member for transferring a rotational power to the yoke.

9. The refrigerator in accordance with claim 1, wherein the first heat exchange unit comprises a first case including the magnetocaloric material, an upper inlet port and an upper outlet port disposed on an upper surface of the first case, and an lower inlet port and an lower outlet port disposed on an lower surface of the first case, and

wherein the second heat exchange unit comprises a second case including the magnetocaloric material, an upper inlet port and an upper outlet port disposed on an upper surface of the second case, and a lower inlet port and a lower outlet port disposed on a lower surface of the second case.

10. The refrigerator in accordance with claim 9, wherein the magnetocaloric material comprises a plurality of magnetocaloric material pieces disposed in the first case or the second case, the plurality of magnetocaloric material pieces have a gap therebetween.

11. The refrigerator in accordance with claim 10, wherein each of the plurality of magnetocaloric material pieces comprises a gadolinium plate.

12. The refrigerator in accordance with claim 10, wherein each of the plurality of magnetocaloric material pieces comprises a gadolinium rod having a constant circular cross-section in the lengthwise direction.

13. The refrigerator in accordance with claim 12, wherein the gadolinium rod comprises a groove in the lengthwise direction.