Magnetocaloric material bed and magnetic refrigerator

Abstract

The present invention obtains a magnetocalorific material bed in which a heat-storing member is provided to a flow path within which a plurality of types of magnetocalorific materials are provided so that the Curie temperatures thereof sequentially increase from one end toward the other end, thereby making it possible to cause the magnetocalorific materials to swiftly reach the respective Curie temperatures when a device is started up, and making it possible to improve the operation efficiency.　This magnetocalorific material bed (10) comprises: a flow path (20) through which a heat exchange fluid (9) flows in a circulatory manner between one end and the other end; a plurality of types of magnetocalorific materials (21) that are provided within the flow path (20) such that the Curie temperatures of the magnetocalorific materials (21) sequentially increase from the one end to the other end, the magnetocalorific materials (21) undergoing heat exchange with the heat exchange fluid (9); and a plurality of types of heat-storing members (22) that are provided to the flow path (20) so that the phase transition temperatures of the heat-storing members (22) sequentially increase from the one end to the other end.

Description

[Technical Field]

[0001] The present disclosure relates to a magnetocaloric material bed and a magnetic refrigerator. [Background technology]

[0002] A magnetic refrigeration system utilizes the phenomenon (hereinafter referred to as the "magnetocaloric effect") in which a magnetic material generates heat when a magnetic field is applied to it and absorbs heat when the magnetic field is removed. The magnetocaloric materials used as the magnetic material in magnetic refrigeration systems are known to exhibit the largest magnetocaloric effect near the Curie point, where the entropy change is large.

[0003] In the prior art, magnetocaloric materials with different properties filled in a magnetocaloric container are arranged in a cascade from the low-temperature side to the high-temperature side, thereby increasing the temperature difference between both ends and improving cooling performance. For example, Patent Document 1 discloses a magnetocaloric effect element and a magnetocaloric cycle device in which the materials are arranged in a cascade such that the Curie temperature increases from the low-temperature end to the high-temperature end, and an element with a relatively low fluid resistance is positioned on the higher temperature side than an element with a relatively high fluid resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-077745 Summary of the Invention [Problem to be solved by the invention]

[0005] The magnetocaloric effect element and the magnetocaloric cycle device described above have each magnetocaloric element arranged in cascade and operate at a temperature where the amount of heat absorbed and generated is large, thereby realizing a magnetocaloric cycle device with high refrigeration capacity. However, when starting up the device, such as at the initial stage of startup or when restarting operation, it takes time for each magnetocaloric element to reach the Curie temperature.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a magnetic refrigeration device and a magnetic refrigeration device in which the magnetic refrigeration material quickly reaches close to the Curie temperature and can efficiently demonstrate refrigeration capacity when the magnetic refrigeration device starts operating, such as at the initial start-up or restart. [Means for solving the problem]

[0007] The magnetocaloric material bed according to the present disclosure comprises a flow path through which a heat exchange fluid flows back and forth between one end and the other end, a plurality of types of magnetocaloric materials which exchange heat with the heat exchange fluid and are arranged within the flow path so that their Curie temperatures increase in order from one end to the other, and a plurality of types of heat storage materials which are arranged within the flow path so that their phase transition temperatures increase in order from one end to the other, wherein the flow path provided with the magnetocaloric material having a Curie temperature lower than the operating environment temperature is provided with a heat storage material having a phase transition temperature higher than the Curie temperature of the magnetocaloric material, and the flow path provided with the magnetocaloric material having a Curie temperature higher than the operating environment temperature is provided with a heat storage material having a phase transition temperature lower than the Curie temperature of the magnetocaloric material. [Effects of the Invention]

[0008] According to the magnetocaloric material bed of the present disclosure, a flow path provided with a magnetocaloric material having a Curie temperature lower than the operating environment temperature is provided with a heat storage material having a phase transition temperature higher than the Curie temperature of the magnetocaloric material, and a flow path provided with a magnetocaloric material having a Curie temperature higher than the operating environment temperature is provided with a heat storage material having a phase transition temperature lower than the Curie temperature of the magnetocaloric material.This has the effect of allowing each magnetocaloric material to quickly reach its Curie temperature when starting up the device, thereby improving operating efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a magnetic refrigeration device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the magnetocaloric material bed according to the first embodiment taken along the line AA shown in FIG. [Figure 3]FIG. 2 is a cross-sectional view taken along the line AA shown in FIG. 1 of a modified example of the magnetocaloric material bed according to the first embodiment. [Figure 4] FIG. 3 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material provided in the flow path of the magnetocaloric material bed according to the first embodiment and the phase transition temperature of the heat storage material. [Figure 5] FIG. 4 is a diagram showing a temperature change of the magnetocaloric material at the other end side of the magnetocaloric material bed according to the first embodiment. [Figure 6] FIG. 2 is a cross-sectional view taken along the line AA shown in FIG. 1 of a modified example of the magnetocaloric material bed according to the first embodiment. [Figure 7] FIG. 3 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material provided in the flow path of the magnetocaloric material bed according to the first embodiment and the phase transition temperature of the heat storage material. [Figure 8] FIG. 2 is a cross-sectional view of a heat storage material covered with capsules provided in a flow path of the magnetocaloric material bed according to the first embodiment. [Figure 9] FIG. 2 is a diagram showing a magnetocaloric material provided across one end side and the other end side in a flow path of the magnetocaloric material bed according to the first embodiment. [Figure 10] FIG. 3 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material provided in the flow path of the magnetocaloric material bed according to the first embodiment and the phase transition temperature of the heat storage material. [Figure 11] FIG. 2 is a diagram showing a magnetocaloric material provided across one end side and the other end side in a flow path of the magnetocaloric material bed according to the first embodiment. [Figure 12] FIG. 3 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material provided in the flow path of the magnetocaloric material bed according to the first embodiment and the phase transition temperature of the heat storage material. [Figure 13] FIG. 10 is a cross-sectional view of a heat storage material covered with magnetocaloric material capsules provided in a flow path of a magnetocaloric material bed according to a second embodiment. [Figure 14] FIG. 2 is a cross-sectional view of a magnetocaloric material bed according to a third embodiment taken along the line AA shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes embodiments in detail with reference to the accompanying drawings. Note that the embodiments described below are merely examples. The embodiments can be implemented in appropriate combination.

[0011] Embodiment 1 FIG. 1 is a schematic diagram of a magnetic refrigeration apparatus according to a first embodiment. FIG. 2 is a cross-sectional view taken along line AA of the magnetocaloric material bed according to the first embodiment. FIG. 3 is a cross-sectional view taken along line AA of a modified example of the magnetocaloric material bed according to the first embodiment. FIG. 4 is a diagram showing a relationship between the Curie temperature of a magnetocaloric material provided in a flow path of the magnetocaloric material bed according to the first embodiment and the phase transition temperature of a heat storage material. FIG. 5 is a diagram showing a temperature change of the magnetocaloric material at the other end of the magnetocaloric material bed according to the first embodiment. FIG. 6 is a cross-sectional view taken along line AA of the modified example of the magnetocaloric material bed according to the first embodiment. FIG. 7 is a diagram showing a relationship between the Curie temperature of a magnetocaloric material provided in a flow path of the magnetocaloric material bed according to the first embodiment and the phase transition temperature of a heat storage material. FIG. 8 is a cross-sectional view of a encapsulated heat storage material provided in a flow path of the magnetocaloric material bed according to the first embodiment. FIG. 9 is a diagram showing a magnetocaloric material provided across the low temperature side and the high temperature side in a flow path of the magnetocaloric material bed according to the first embodiment. Fig. 10 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material provided in the flow path of the magnetocaloric material bed according to embodiment 1 and the phase transition temperature of the heat storage material. Fig. 11 is a diagram showing the magnetocaloric material provided so as to straddle the low temperature side and the high temperature side in the flow path of the magnetocaloric material bed according to embodiment 1. Fig. 12 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material provided in the flow path of the magnetocaloric material bed according to embodiment 1 and the phase transition temperature of the heat storage material.

[0012] 1, the magnetic refrigeration device 1 includes a low-temperature side heat exchanger 2, a high-temperature side heat exchanger 3, a fan 4, a pump 5, a magnetic field modulation device 6, a water pipe 7, and a magnetocaloric material bed 10. The magnetocaloric material bed 10 will be described in detail later.

[0013] Here, the magnetic refrigeration device 1 is a heat pump system that heats one side of the flow path 20 of the magnetocaloric material bed 10 to a high temperature and the other side of the flow path 20 to a low temperature. Therefore, the flow path 20 of the magnetocaloric material bed 10 has a high temperature side that is a high temperature range and a low temperature side that is a low temperature range. Also, the position with the highest temperature on the high temperature side is called the high temperature end, and the position with the lowest temperature on the low temperature side is called the low temperature end. In other words, the high temperature end and the low temperature end of the flow path 20 refer to the vicinity of the outlet when the heat exchange fluid 9 is transported from the flow path 20 to the water pipe 7.

[0014] The low-temperature side heat exchanger 2 is connected to the low-temperature end of the flow path 20 of the magnetocaloric material bed 10 via a water pipe 7. A cooled medium flow path (not shown) is also connected to the low-temperature side heat exchanger 2, and a heat exchange fluid 9 supplied from the low-temperature end of the flow path 20 of the magnetocaloric material bed 10 via the water pipe 7 to the low-temperature side heat exchanger 2 exchanges heat with the cooled medium flowing in the cooled medium flow path. In other words, the heat exchange fluid 9 supplied to the low-temperature side heat exchanger 2 exchanges heat with the cooled medium and absorbs heat. The cooled medium referred to here refers to a liquid such as water.

[0015] Here, the heat exchange fluid 9 is a fluid that flows in the flow path 20 of the low-temperature side heat exchanger 2, the high-temperature side heat exchanger 3, the water pipe 7, and the magnetocaloric material bed 10, and travels back and forth between the low-temperature side heat exchanger 2 and the high-temperature side heat exchanger 3. The heat exchange fluid 9 may be, for example, water or brine.

[0016] The high-temperature side heat exchanger 3 is connected to the high-temperature end of the flow path 20 of the magnetocaloric material bed 10 via a water pipe 7. Therefore, the low-temperature side heat exchanger 2 and the high-temperature side heat exchanger 3 are connected so as to sandwich the magnetocaloric material bed 10 via the water pipe 7. Furthermore, as shown in Fig. 1 , the high-temperature side heat exchanger 3 is provided with a fan 4 that performs heat exchange between a heat exchange fluid 9 supplied from the high-temperature end of the flow path 20 of the magnetocaloric material bed 10 to the high-temperature side heat exchanger 3 via the water pipe 7 and air. In other words, the heat exchange fluid 9 supplied to the high-temperature side heat exchanger 3 exchanges heat with the air to exhaust heat, and the air after heat exchange is transported by the fan 4.

[0017] Here, an example has been shown in which the heat exchange fluid 9 supplied to the low-temperature side heat exchanger 2 exchanges heat with a cooled medium such as water, but this is not limiting. For example, if the cooled medium is air, the heat exchange fluid 9 supplied to the low-temperature side heat exchanger 2 exchanges heat with the air, and the air after heat exchange is transported using the fan 4. Similarly, the heat exchange fluid 9 supplied to the high-temperature side heat exchanger 3 may exchange heat with a liquid such as water. In other words, the partner with which the heat exchange fluid 9 exchanges heat can be changed depending on the application.

[0018] The pump 5 is a reciprocating pump configured to transport the heat exchange fluid 9 between the low-temperature side heat exchanger 2 and the high-temperature side heat exchanger 3, so as to reciprocate via the magnetocaloric material bed 10. In other words, the pump 5 transports the heat exchange fluid 9 so as to repeatedly reciprocate between the low-temperature side heat exchanger 2, the magnetocaloric material bed 10, and the high-temperature side heat exchanger 3.

[0019] 1 shows the pump 5 connected via the water pipe 7 between the low-temperature side heat exchanger 2 and the high-temperature side heat exchanger 3 on the side opposite to the magnetocaloric material bed 10, but the connection position of the pump 5 is not limited to this. For example, the pump 5 may be connected via the water pipe 7 between the magnetocaloric material bed 10 and the low-temperature side heat exchanger 2 or between the magnetocaloric material bed 10 and the high-temperature side heat exchanger 3. In this case, however, the heat capacity of the pump 5 reduces the temperature difference between the high-temperature end and the low-temperature end of the flow path 20 of the magnetocaloric material bed 10, so it is preferable to connect the pump 5 via the water pipe 7 between the low-temperature side heat exchanger 2 and the high-temperature side heat exchanger 3 on the side opposite to the magnetocaloric material bed 10.

[0020] 1, the magnetic field modulators 6 are provided opposite to each other so as to sandwich the entire side surface of the magnetocaloric material bed 10. The magnetic field modulators 6 are configured to be able to vary the magnetic field applied to the magnetocaloric material 21 provided in the flow path 20 of the magnetocaloric material bed 10.

[0021] The magnetic field modulator 6 may be of any type as long as it is capable of applying and removing a magnetic field to the magnetocaloric material 21 provided in the flow path 20 of the magnetocaloric material bed 10. For example, in the case of a magnetic field modulator 6 using a permanent magnet, the magnetocaloric material bed 10 is fixed and the magnetic field is varied by moving the permanent magnet closer to or farther away from the magnetocaloric material bed 10. Alternatively, the permanent magnet may be fixed and the magnetic field may be varied by moving the magnetocaloric material bed 10 closer to or farther away from the permanent magnet. However, in the case of a magnetic field modulator 6 using a permanent magnet, if the magnetic field modulator 6 is located far from the magnetocaloric material bed 10, the magnetic force of the permanent magnet weakens and a sufficient magnetic field cannot be applied, so it is preferable to locate the magnetocaloric material bed 10 and the magnetic field modulator 6 close to each other.

[0022] Furthermore, in the case of a magnetic field modulation device 6 using an electromagnet, it is excited by passing a current through it and demagnetized by stopping the current, thereby fluctuating the magnetic field to the magnetocaloric material 21. In this case, since the magnetic field can be fluctuated by passing or stopping the current through it, the magnetic field modulation device 6 does not need to be installed close to the magnetocaloric material bed 10, and the installation location and installation method are not important as long as it can apply and remove a magnetic field to the magnetocaloric material 21.

[0023] The water pipes 7 are provided between the low-temperature side heat exchanger 2 and the magnetocaloric material bed 10, between the high-temperature side heat exchanger 3 and the magnetocaloric material bed 10, between the low-temperature side heat exchanger 2 and the pump 5, and between the high-temperature side heat exchanger 3 and the pump 5, and are pipes for transporting the heat exchange fluid 9. The shape of the water pipes 7 is not limited to that shown in Fig. 1 and may be changed as appropriate.

[0024] The magnetocaloric material bed 10 will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view taken along line AA in Fig. 1 of a modified example of the magnetocaloric material bed 10. As shown in Fig. 2, the magnetocaloric material bed 10 has a flow path 20 formed by a flange 12 and a bed wall 11.

[0025] The flanges 12 are provided at the low temperature end and the high temperature end of the flow path 20, and connect the water pipes 7 and the flow path 20. Note that, although Fig. 2 shows the magnetocaloric material bed 10 to which the water pipes 7 are connected via the flanges 12, this is only an example, and the water pipes 7 and the flow path 20 may be directly connected without using the flanges 12.

[0026] The flow path 20 is formed by the bed wall 11 and is a water channel through which the heat exchange fluid 9 flows. The flow path 20 has a low-temperature end at one end and a high-temperature end at the other end, and the heat exchange fluid 9 supplied from the low-temperature side heat exchanger 2 through the water pipe 7 flows from one end to the other end of the flow path 20. Similarly, the heat exchange fluid 9 supplied from the high-temperature side heat exchanger 3 through the water pipe 7 flows from the other end to one end of the flow path 20. In other words, the heat exchange fluid 9 flows back and forth between one end and the other end of the flow path 20 by the pump 5.

[0027] Also provided within the flow path 20 is a magnetocaloric material 21 that exchanges heat with the heat exchange fluid 9. The magnetocaloric materials 21 are provided within the flow path 20 so that their Curie temperatures increase in order from one end to the other end of the flow path 20. Here, the Curie temperature is the temperature at which a magnetic material loses its magnetic force.

[0028] Next, the magnetocaloric material 21 provided in the flow path 20 will be described in detail with reference to Fig. 2. As shown in Fig. 2, four different types of magnetocaloric materials 21a, 21b, 21c, and 21d are provided in the flow path 20. Furthermore, the magnetocaloric material 21 is composed of a plurality of particles, and a plurality of types of magnetocaloric materials 21 each composed of a plurality of particles are provided in the flow path 20. Here, the Curie temperatures of the magnetocaloric materials 21 are designated as magnetocaloric materials 21a, 21b, 21c, and 21d in order of decreasing Curie temperature.

[0029] In the flow path 20 of the magnetocaloric material bed 10 in this embodiment, the magnetocaloric material 21 is provided such that the magnetocaloric material 21a is provided at one end of the flow path 20, and magnetocaloric materials 21 with higher Curie temperatures are provided toward the other end. That is, the magnetocaloric materials 21 are provided in the flow path 20 in the order of magnetocaloric materials 21a, 21b, 21c, and 21d from one end of the flow path 20 to the other end.

[0030] Note that arranging magnetocaloric materials 21 with higher Curie temperatures from the low temperature end to the high temperature end of the flow path 20 is referred to as a cascade arrangement. In this embodiment, an example in which four types of magnetocaloric materials 21a, 21b, 21c, and 21d are arranged in a cascade arrangement as shown in Fig. 2 has been shown, but the number of types of magnetocaloric materials 21 is not limited as long as multiple types of magnetocaloric materials 21 are arranged in a cascade arrangement within the flow path 20. However, the more types of magnetocaloric materials 21 are arranged within the flow path 20, the greater the temperature difference between one end and the other end of the flow path 20 can be, and therefore the more efficient the refrigeration capacity exhibited by the magnetic refrigeration device 1 can be.

[0031] Furthermore, the magnetocaloric materials 21 are spread out in the flow path 20 so that adjacent magnetocaloric materials 21 of different types do not mix with each other due to the flow of the heat exchange fluid 9. However, when the heat exchange fluid 9 repeatedly travels back and forth within the flow path 20 for a long period of time, the magnetocaloric materials 21 may be mixed with each other due to the flow of the heat exchange fluid 9. Therefore, a mesh 13 may be provided to separate adjacent magnetocaloric materials 21 of different types so that the magnetocaloric materials 21 do not mix with each other due to the flow of the heat exchange fluid 9.

[0032] Fig. 3 is a cross-sectional view taken along the line AA of Fig. 1 of a modified example of the magnetocaloric material bed 10. As shown in Fig. 3, the magnetocaloric materials 21 arranged in cascade in the flow path 20 are partitioned by a mesh 13 so that different types of magnetocaloric materials 21 do not mix with each other. Note that the type of mesh 13 is not important as long as it is made of a material and has a shape that allows the heat exchange fluid 9 to pass through but does not allow the magnetocaloric materials 21 to pass through. Furthermore, if the magnetocaloric materials 21 are provided in the flow path 20 without being mixed with each other by the flow of the heat exchange fluid 9, the mesh 13 does not necessarily have to be provided in the flow path 20.

[0033] Furthermore, although not shown, the mesh 13 may be provided between the water pipe 7 and the flow path 20 at the low temperature end and the high temperature end of the flow path 20. In this way, by providing the mesh 13 between the water pipe 7 and the flow path 20, it is possible to prevent the magnetocaloric material 21 from flowing out into the water pipe 7. When the mesh 13 is provided between the water pipe 7 and the flow path 20 at the low temperature end and the high temperature end of the flow path 20, it is advisable to provide a spacer between the flange 12 and the mesh 13, for example, to fix the mesh 13.

[0034] Here, when the magnetocaloric material 21 provided in the flow path 20 of the magnetocaloric material bed 10 is magnetized, its magnetic entropy decreases and it emits heat, generating heat when its electron spins are aligned in the magnetic field direction. On the other hand, when the electron spins become disordered by demagnetization, its magnetic entropy increases and it absorbs heat. Therefore, it is recommended that the magnetocaloric material 21 be a magnetic material that exhibits a high magnetocaloric effect at room temperature, such as a mixture of manganese, iron, phosphorus, and germanium, or a gadolinium-based material or alloy.

[0035] Next, the heat storage material 22 provided in the flow path 20 will be described with reference to Figs. 2 to 7. Fig. 4 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material 21 provided in the flow path 20 of the magnetocaloric material bed 10 according to the first embodiment and the phase transition temperature of the heat storage material 22. Fig. 5 is a diagram showing the temperature change of the magnetocaloric material 21 at the other end side of the magnetocaloric material bed 10 according to the first embodiment. Fig. 6 is a cross-sectional view taken along line AA shown in Fig. 1 of a modified example of the magnetocaloric material bed 10 according to the first embodiment. Fig. 7 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material 21 provided in the flow path 20 of the magnetocaloric material bed 10 according to the first embodiment and the phase transition temperature of the heat storage material 22.

[0036] 2 and 3, magnetocaloric materials 21 are provided in the flow path 20 of the magnetocaloric material bed 10 so that the Curie temperatures increase in order from one end of the flow path 20 to the other end. In addition, multiple types of heat storage materials 22 are provided in the flow path 20.

[0037] The heat storage materials 22 are provided in the flow path 20 so that their phase transition temperatures increase in order from one end to the other end of the flow path 20. The heat storage material 22 provided at one end has a phase transition temperature higher than the Curie temperature of the magnetocaloric material 21 provided at one end, and the heat storage material 22 provided at the other end has a phase transition temperature lower than the Curie temperature of the magnetocaloric material 21 provided at the other end. Here, the phase transition temperature refers to the temperature at which a phase transition occurs.

[0038] An explanation will be given with reference to Figures 2 and 4. As shown in Figure 2, magnetocaloric material 21 is provided with magnetocaloric materials 21a, 21b, 21c, and 21d in this order from one end of flow path 20. Heat storage material 22 is provided with heat storage material 22b on one end side and heat storage material 22c on the other end side.

[0039] 4 is a graph showing the relationship between the Curie temperature of the magnetocaloric material 21 and the phase transition temperature of the heat storage material 22. Here, the operating environment temperature shown in Fig. 4 refers to the temperature of the environment in which the magnetocaloric material bed 10 is installed. For example, it refers to the outdoor air temperature when the magnetocaloric material bed 10 is installed outdoors, and refers to the indoor temperature when the magnetocaloric material bed 10 is installed indoors.

[0040] As shown in Fig. 4, the heat storage material 22b provided at one end has a phase transition temperature higher than the Curie temperatures of the magnetocaloric materials 21a and 21b provided at one end. On the other hand, the heat storage material 22c provided at the other end has a phase transition temperature lower than the Curie temperatures of the magnetocaloric materials 21c and 21d provided at the other end. Furthermore, the phase transition temperature of the heat storage material 22 provided at the other end of the flow path 20, i.e., the heat storage material 22c, is higher than the operating environment temperature, while the phase transition temperature of the heat storage material 22 provided at one end, i.e., the heat storage material 22b, is lower than the operating environment temperature. Furthermore, the phase transition temperature of the heat storage material 22c provided at the other end of the flow path 20 is higher than the phase transition temperature of the heat storage material 22b provided at one end.

[0041] 5 is a diagram showing the temperature change of the magnetocaloric material 21 at the other end of the flow path 20. The vertical axis represents temperature, and the horizontal axis represents time. The thick solid and dotted lines represent the temperature change when the heat storage material 22 is present in the flow path 20, and the thin solid and dotted lines represent the temperature change when the heat storage material 22 is not present in the flow path 20. K1 represents the phase transition temperature, K2 represents the Curie temperature, t0 represents the time when the magnetic refrigeration device 1 is stopped, t1 represents the time when the magnetic refrigeration device 1 is restarted, and T1 and T2 represent the time from restart until the Curie temperature is reached. The solid line represents the temperature change of the magnetocaloric material 21 when the magnetic refrigeration device 1 is restarted, and the dotted line represents the temperature change after the magnetic refrigeration device 1 is stopped without being restarted.

[0042] As shown in FIG. 5, since the Curie temperature K2 of the magnetocaloric material 21 is higher than the operating environment temperature, the temperature of the magnetocaloric material 21 decreases due to heat dissipation to the outside immediately after the operation stops. On the other hand, when the heat storage material 22 is provided in the flow path 20, heat moves from the heat storage material 22 to the magnetocaloric material 21 after the operation stops. Therefore, compared with the case where the heat storage material 22 is not provided in the flow path 20, the temperature change of the magnetocaloric material 21 becomes gentle. That is, the temperature change of the magnetocaloric material 21 after the magnetic refrigeration device 1 stops varies greatly depending on whether the heat storage material 22 is provided in the flow path 20 or not. The time required for the temperature of the magnetocaloric material 21 to reach the Curie temperature K2 after restart is shorter for the magnetocaloric material 21 with the heat storage material 22 provided in the flow path 20 than for the magnetocaloric material 21 without the heat storage material 22 provided in the flow path 20 (T2 < T1). Although the explanation is omitted, the same applies to the low-temperature side. The magnetocaloric material 21 with the heat storage material 22 provided in the flow path 20 reaches the Curie temperature after the magnetic refrigeration device 1 restarts in a shorter time than the magnetocaloric material 21 without the heat storage material 22 provided in the flow path 20.

[0043] From the above, the magnetocaloric material bed 10 can reduce the temperature change of the magnetocaloric material 21 after the magnetic refrigeration device 1 stops by providing the heat storage material 22 with a phase transition temperature higher than the Curie temperature of the magnetocaloric material 21 provided on one end side and a phase transition temperature lower than the Curie temperature of the magnetocaloric material 21 provided on the other end side in the flow path 20. Also, after the magnetic refrigeration device 1 restarts, the temperature of the magnetocaloric material 21 can quickly reach the Curie temperature.

[0044] 6 shows an example of a magnetocaloric material bed 10 in which four types of heat storage materials 22a, 22b, 22c, and 22d with different phase transition temperatures are provided in a flow path 20. As shown in FIG. 6, the heat storage materials 22 are provided in the flow path 20 corresponding to the different types of magnetocaloric materials 21. That is, at one end of the flow path 20, the heat storage material 22a is provided in the flow path 20 in which the magnetocaloric material 21a is provided, and the heat storage material 22b is provided in the flow path 20 in which the magnetocaloric material 21b is provided. Similarly, at the other end of the flow path 20, the heat storage material 22c is provided in the flow path 20 in which the magnetocaloric material 21c is provided, and the heat storage material 22d is provided in the flow path 20 in which the magnetocaloric material 21d is provided. In this way, the magnetocaloric materials 21 and the heat storage materials 22 are arranged in pairs in the flow path 20.

[0045] 7 shows the relationship between the Curie temperature of the magnetocaloric material 21 provided in the flow path 20 and the phase transition temperature of the heat storage material 22. At one end of the flow path 20, a heat storage material 22a having a phase transition temperature higher than the Curie temperature of the magnetocaloric material 21a is provided in the flow path 20 provided with the magnetocaloric material 21a, and a heat storage material 22b having a phase transition temperature higher than the Curie temperature of the magnetocaloric material 21b is provided in the flow path 20 provided with the magnetocaloric material 21b. On the other hand, at the other end of the flow path 20, a heat storage material 22c having a phase transition temperature lower than the Curie temperature of the magnetocaloric material 21c is provided in the flow path 20 provided with the magnetocaloric material 21c, and a heat storage material 22d having a phase transition temperature lower than the Curie temperature of the magnetocaloric material 21d is provided in the flow path 20 provided with the magnetocaloric material 21d. The phase transition temperatures of the heat storage materials 22a and 22b provided at one end of the flow path 20 are lower than the operating environment temperature, and the phase transition temperatures of the heat storage materials 22c and 22d provided at the other end of the flow path 20 are higher than the operating environment temperature. In this way, the heat storage materials 22 are provided in the flow path 20 in correspondence with the respective magnetocaloric materials 21.

[0046] As described above, the multiple types of heat storage materials 22 provided in the flow path 20 are arranged so that their phase transition temperatures increase from one end to the other end in correspondence with the respective magnetocaloric materials 21. Furthermore, the heat storage materials 22 provided in the flow path 20 have a phase transition temperature higher than the Curie temperature of the magnetocaloric materials 21 provided at one end, and a phase transition temperature lower than the Curie temperature of the magnetocaloric materials 21 provided at the other end. By providing the heat storage materials 22 in correspondence with the types of magnetocaloric materials 21 provided in the flow path 20 in this manner, the temperature change of the magnetocaloric materials 21 after the magnetic refrigeration device 1 is shut down can be reduced compared to the magnetic refrigeration device 1 including the magnetocaloric material bed 10 shown in FIG. 2. Furthermore, the temperature of the magnetocaloric materials 21 can be quickly raised to the Curie temperature after the magnetic refrigeration device 1 is restarted. This improves operating efficiency and saves energy.

[0047] Here, a latent heat storage material may be used for the heat storage material 22 provided in the flow path 20. Examples of materials that can be used include saturated hydrocarbons, fatty acids such as stearic acid or palmitic acid, low-melting-point metals such as potassium or sodium or alloys thereof, sugar alcohols such as erythritol and threitol, hydrated salts such as sodium acetate trihydrate or sodium thiosulfate pentahydrate, molten salts such as calcium chloride or lithium chloride, clathrate hydrates such as tetrabutylammonium bromide, and water. These latent heat storage materials can store a large amount of heat by absorbing and releasing a large amount of latent heat when they undergo a phase transition from solid to liquid or from liquid to solid.

[0048] On the other hand, when these latent heat storage materials are used as the heat storage material 22, they become liquid above their melting point, and therefore, if the latent heat storage material is provided as it is in the flow path 20 of the magnetocaloric material bed 10 as the heat storage material 22, the heat storage material 22 will melt as the temperature rises. After the melted heat storage material 22 moves through the flow path 20 together with the heat exchange fluid 9, it cools down and solidifies, which may clog the water pipe 7, causing a decrease in refrigeration performance due to a decrease in flow rate and leading to breakdowns.

[0049] Therefore, it is preferable to cover the heat storage material 22 with a capsule 23 as shown in Fig. 8 to prevent the heat storage material 22 from melting and moving inside the flow path 20. Here, the material of the capsule 23 may be, for example, melamine, acrylic, urethane, or silica. By covering the heat storage material 22 with the capsule 23 in this way, when the heat storage material 22 melts and becomes liquid, it does not mix with the heat exchange fluid 9, and therefore it is possible to prevent the heat storage material 22 from solidifying and clogging the water pipe 7.

[0050] Furthermore, it is preferable to use a latent heat storage material, such as vanadium oxide, that stores heat during a solid-to-solid phase transition, as the heat storage material 22. When such a latent heat storage material is provided in the flow path 20 as the heat storage material 22, the heat storage material 22 does not melt and mix with the heat exchange fluid 9, so there is no need to cover it with the capsule 23, and the amount of heat stored per volume can be increased.

[0051] Next, the operating principle of the magnetic refrigeration device 1 will be described.

[0052] When the magnetocaloric material 21 provided in the flow path 20 of the magnetocaloric material bed 10 is excited by the magnetic field modulation device 6, the magnetocaloric material 21 generates heat due to the magnetocaloric effect. The heat of the magnetocaloric material 21 is thermally conducted to the heat exchange fluid 9 adjacent to the magnetocaloric material 21.

[0053] The pump 5 transports the heat exchange fluid 9 in the water pipe 7, the low-temperature side heat exchanger 2, and the magnetocaloric material bed 10 from the low-temperature side heat exchanger 2 side to the high-temperature side heat exchanger 3 side via the magnetocaloric material bed 10, and the heat of the magnetocaloric material 21 is carried to the high-temperature side heat exchanger 3 by the heat exchange fluid 9. The heat exchange fluid 9 carried to the high-temperature side heat exchanger 3 is cooled by exchanging heat with the air, and its temperature drops.

[0054] Next, when the magnetocaloric material 21 provided in the flow path 20 of the magnetocaloric material bed 10 is demagnetized by the magnetic field modulation device 6, the magnetocaloric material 21 generates cold heat due to the magnetocaloric effect. The cold heat of the magnetocaloric material 21 is thermally conducted to the heat exchange fluid 9 adjacent to the magnetocaloric material 21.

[0055] The pump 5 transports the heat exchange fluid 9 in the water pipe 7, the high-temperature side heat exchanger 3, and the magnetocaloric material bed 10 from the high-temperature side heat exchanger 3 side to the low-temperature side heat exchanger 2 side via the magnetocaloric material bed 10, and the cold energy of the magnetocaloric material 21 is carried to the low-temperature side heat exchanger 2 by the heat exchange fluid 9. The heat exchange fluid 9 carried to the low-temperature side heat exchanger 2 exchanges heat with the cooled medium flowing through the cooled medium flow path, and the temperature rises.

[0056] In this way, by repeating the above steps, a magnetic refrigeration cycle is realized in which cold heat is transported to the low-temperature side heat exchanger 2 and hot heat is transported to the high-temperature side heat exchanger 3.

[0057] As described above, the magnetocaloric material bed 10 shown in this embodiment includes a plurality of types of magnetocaloric materials 21 provided in a flow path 20 so that their Curie temperatures increase sequentially from one end to the other, and a plurality of types of heat storage materials 22 provided in the flow path 20 so that their phase transition temperatures increase sequentially from one end to the other. In the flow path 20, heat storage materials 22 having a phase transition temperature higher than the Curie temperature of the magnetocaloric materials 21 are provided in the flow path 20 where the magnetocaloric materials 21 have a Curie temperature lower than the operating ambient temperature, and heat storage materials 22 having a phase transition temperature lower than the Curie temperature of the magnetocaloric materials 21 are provided in the flow path 20 where the magnetocaloric materials 21 have a Curie temperature higher than the operating ambient temperature. This configuration allows each magnetocaloric material 21 to quickly reach its Curie temperature when starting up the magnetic refrigeration device 1, such as at the time of initial startup or restarting operation, thereby improving operating efficiency.

[0058] In this embodiment, the magnetocaloric material bed 10 is shown in which the magnetocaloric material 21 and the heat storage material 22 are provided in the flow path 20 of the magnetocaloric material bed 10 such that the magnetocaloric material 21 is provided in a larger amount than the heat storage material 22. However, the ratio of the magnetocaloric material 21 to the heat storage material 22 is not particularly limited and may be changed appropriately depending on the required specifications. For example, if a large temperature difference between one end and the other end of the flow path 20 is required, the ratio of the heat storage material 22 is reduced and the ratio of the magnetocaloric material 21 is increased. On the other hand, if the magnetic refrigeration device 1 is frequently shut down and restarted, it is required that the temperature of the magnetocaloric material 21 quickly reach the Curie temperature. In such a case, the ratio of the heat storage material 22 is higher than in a magnetocaloric material bed 10 when a large temperature difference is required. In this way, by changing the ratio of the heat storage material 22 in the flow path 20 of the magnetocaloric material bed 10 depending on the application, a magnetocaloric material bed 10 suited to the required specifications can be obtained.

[0059] Furthermore, in this embodiment, the magnetocaloric material bed 10 is shown in which four types of magnetocaloric materials 21a, 21b, 21c, and 21d are provided in the flow path 20 so that their Curie temperatures increase in order from one end to the other. The magnetocaloric material bed 10 is configured such that two types of materials are provided at each end, i.e., the magnetocaloric materials 21a and 21b at one end and the magnetocaloric materials 21c and 21d at the other end, in the flow path 20, but a magnetocaloric material bed 10 in which the magnetocaloric material 21 is provided so as to straddle one end and the other end will also be described.

[0060] A magnetocaloric material bed 10 in which the magnetocaloric material 21 is provided so as to straddle one end side and the other end side will be described with reference to Figs. 9 to 12. Fig. 9 is a cross-sectional view taken along line AA in Fig. 1 of the magnetocaloric material bed 10 in which the magnetocaloric material 21 is provided so as to straddle one end side and the other end side. Fig. 10 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material 21 provided in the flow path 20 and the phase transition temperature of the heat storage material 22. Fig. 11 is a cross-sectional view taken along line AA in Fig. 1 of the magnetocaloric material bed 10 in which the magnetocaloric material 21 is provided so as to straddle one end side and the other end side. Fig. 12 is a diagram showing the relationship between the Curie temperature of the magnetocaloric material 21 provided in the flow path 20 and the phase transition temperature of the heat storage material 22.

[0061] As shown in FIG. 9, a magnetocaloric material 21b is provided in a flow path 20, straddling from one end to the other end. In this case, a heat storage material 22b is provided in the flow path 20 in which the magnetocaloric material 21b is provided. That is, as shown in FIG. 10, when a magnetocaloric material 21b having a Curie temperature lower than the operating environment temperature is provided so as to straddle both one end and the other end, a heat storage material 22b having a phase transition temperature higher than the Curie temperature of the magnetocaloric material 21b is provided in the flow path 20 in which the magnetocaloric material 21b is provided at one end. On the other hand, a heat storage material 22b is also provided in the flow path 20 in which the magnetocaloric material 21b at the other end is provided. That is, a heat storage material 22 having a phase transition temperature higher than the Curie temperature of the magnetocaloric material 21 is provided in the flow path 20 in which magnetocaloric materials 21 having a Curie temperature lower than the operating environment temperature are provided at both one end and the other end.

[0062] As shown in FIG. 11 , a magnetocaloric material 21c is provided in a flow path 20, straddling from one end to the other end. In this case, a heat storage material 22c is provided in the flow path 20 in which the magnetocaloric material 21c is provided. That is, as shown in FIG. 12 , when a magnetocaloric material 21c having a Curie temperature lower than the operating environment temperature is provided so as to straddle both one end and the other end, a heat storage material 22c having a phase transition temperature higher than the Curie temperature of the magnetocaloric material 21c is provided in the flow path 20 in which the magnetocaloric material 21c on the other end is provided. On the other hand, a heat storage material 22c is also provided in the flow path 20 in which the magnetocaloric material 21c on the one end is provided. That is, a heat storage material 22 having a phase transition temperature lower than the Curie temperature of the magnetocaloric material 21 is provided in the flow path 20 in which magnetocaloric materials 21 having a Curie temperature higher than the operating environment temperature are provided on both one end and the other end.

[0063] From the above, when the magnetocaloric material bed 10 is configured such that the magnetocaloric material 21 is provided in the flow path 20 so as to span both one end side and the other end side, the same type of heat storage material 22 is provided in the flow path 20 in which the magnetocaloric material 21 is provided so as to span both one end side and the other end side, rather than providing different types of heat storage material 22 on each of the one end side and the other end side.

[0064] Embodiment 2 This embodiment will be described with reference to Fig. 13. Fig. 13 is a cross-sectional view of a heat storage material covered with magnetocaloric material capsules in a magnetocaloric material bed according to a second embodiment.

[0065] In the first embodiment, the heat storage material 22 is covered with capsules 23 so as not to melt and mix with the heat exchange fluid 9 and move within the flow path 20. In the present embodiment, the heat storage material 22 is covered with magnetocaloric material capsules 24 formed of magnetocaloric material 21, and a magnetocaloric material bed 10a is shown, which is provided within the flow path 20 of the magnetocaloric material bed 10a. Other configurations are the same as those in the first embodiment, and the same components as those in the first embodiment are assigned the same numbers, and description thereof will be omitted.

[0066] The magnetocaloric material bed 10a according to this embodiment includes a plurality of types of magnetocaloric materials 21 arranged in a flow path 20 so that their Curie temperatures increase from one end to the other, and a plurality of types of heat storage materials 22 arranged in the flow path 20 so that their phase transition temperatures increase from one end to the other. In the flow path 20, a heat storage material 22 having a phase transition temperature higher than the Curie temperature of the magnetocaloric material 21 is arranged in a flow path 20 in which a magnetocaloric material 21 having a Curie temperature lower than the operating ambient temperature is arranged, and a heat storage material 22 having a phase transition temperature lower than the Curie temperature of the magnetocaloric material 21 is arranged in a flow path 20 in which a magnetocaloric material 21 having a Curie temperature higher than the operating ambient temperature is arranged. This allows the temperature change of the magnetocaloric material 21 to be reduced after the magnetic refrigeration device 1 is shut down. Furthermore, the temperature of the magnetocaloric material 21 can be quickly brought to the Curie temperature after the magnetic refrigeration device 1 is restarted.

[0067] 13, the heat storage material 22 according to this embodiment is covered with magnetocaloric material capsules 24 formed of magnetocaloric material 21. The magnetocaloric material 21 forming the magnetocaloric material capsules 24 is the magnetocaloric material 21 adjacent to the heat storage material 22 in the flow path 20. For example, in the case of the heat storage material 22a shown in FIG. 6, the magnetocaloric material 21 forming the magnetocaloric material capsules 24 covering the heat storage material 22a is the magnetocaloric material 21a adjacent to the heat storage material 22a.

[0068] As described above, in the magnetocaloric material bed 10a according to this embodiment, the heat storage material 22 is covered with the magnetocaloric material capsules 24 formed of the magnetocaloric material 21 and is provided in the flow path 20 of the magnetocaloric material bed 10a. With this configuration, it is not necessary to use capsules made of a material different from the magnetocaloric material 21, and the volume inside the flow path 20 of the magnetocaloric material bed 10a can be used effectively. Therefore, the amount of the magnetocaloric material 21 can be increased, and a high magnetic refrigeration effect can be obtained.

[0069] Embodiment 3 This embodiment will be described with reference to Fig. 14. Fig. 14 is a cross-sectional view of a magnetocaloric material bed according to a third embodiment.

[0070] The first embodiment shows a magnetocaloric material bed 10 in which a heat storage material 22 is provided in the flow path 20 of the magnetocaloric material bed 10. In the present embodiment, a magnetocaloric material bed 10b is shown in which a heat storage material 22 is provided on a bed wall 11a forming a flow path 20a. Other configurations are the same as those in the first embodiment, and the same components as those in the first embodiment are assigned the same numbers and description thereof will be omitted.

[0071] The magnetocaloric material bed 10b according to this embodiment includes a plurality of types of magnetocaloric materials 21 arranged in a flow path 20a so that their Curie temperatures increase from one end to the other, and a plurality of types of heat storage materials 22 arranged in the flow path 20a so that their phase transition temperatures increase from one end to the other. In the flow path 20a, the heat storage materials 22 having a phase transition temperature higher than the Curie temperature of the magnetocaloric materials 21 are arranged in the flow path 20a where the magnetocaloric materials 21 have a Curie temperature lower than the operating ambient temperature, and the heat storage materials 22 having a phase transition temperature lower than the Curie temperature of the magnetocaloric materials 21 are arranged in the flow path 20a where the magnetocaloric materials 21 have a Curie temperature higher than the operating ambient temperature. This minimizes temperature changes in the magnetocaloric materials 21 after the magnetic refrigeration device 1 is shut down. Furthermore, the temperature of the magnetocaloric materials 21 can be quickly raised to the Curie temperature after the magnetic refrigeration device 1 is restarted.

[0072] Further, as shown in Fig. 14, a heat storage material 22 is provided on the bed wall 11a of the flow path 20a. In Fig. 14, four types of heat storage materials 22a, 22b, 22c, and 22d are provided on the bed wall 11a of the flow path 20a in the order of heat storage materials 22a, 22b, 22c, and 22d from the low temperature end to the high temperature end of the flow path 20a. In other words, the position where the heat storage material 22 is provided is different from that of the magnetocaloric material bed 10 shown in the first embodiment.

[0073] In this way, by providing the heat storage material 22 on the bed wall 11a of the flow path 20a, the heat capacity in the flow path 20a of the magnetocaloric material bed 10b can be increased. Furthermore, after the magnetic refrigeration device 1 is stopped, a sudden change in temperature of the magnetocaloric material 21 can be suppressed, and the time required for the magnetocaloric material 21 to reach the Curie temperature when the device is restarted can be shortened, so that the refrigeration capacity starts up quickly, operation efficiency is improved, and energy is saved. [Explanation of symbols]

[0074] 1 magnetic refrigeration device, 2 low-temperature side heat exchanger, 3 high-temperature side heat exchanger, 4 fan, 5 pump, 6 magnetic field modulation device, 7 water tube, 9 heat exchange fluid, 10, 10a, 10b magnetocaloric material bed, 11, 11a bed wall, 12 flange, 13 mesh, 20, 20a flow path, 21 magnetocaloric material, 22 heat storage material, 23 capsule, 24 magnetocaloric material capsule

Claims

1. a flow path through which a heat exchange fluid flows back and forth between one end and the other end; a plurality of magnetocaloric materials that exchange heat with the heat exchange fluid and are provided in the flow path so that their Curie temperatures increase in order from the one end to the other end; a plurality of types of heat storage materials provided in the flow path such that their phase transition temperatures increase in order from the one end to the other end; Equipped with A magnetocaloric material bed characterized in that the flow path provided with the magnetocaloric material having a Curie temperature lower than the operating environment temperature is provided with the heat storage material having a phase transition temperature higher than the Curie temperature of the magnetocaloric material, and the flow path provided with the magnetocaloric material having a Curie temperature higher than the operating environment temperature is provided with the heat storage material having a phase transition temperature lower than the Curie temperature of the magnetocaloric material.

2. 2. The magnetocaloric material bed according to claim 1, wherein the heat storage material provided at one end has a phase transition temperature higher than the Curie temperature of the magnetocaloric material provided at the one end, and the heat storage material provided at the other end has a phase transition temperature lower than the Curie temperature of the magnetocaloric material provided at the other end.

3. 3. The magnetocaloric material bed according to claim 1, wherein the heat storage material is provided in correspondence with each of the magnetocaloric materials.

4. 3. The magnetocaloric material bed according to claim 1, wherein the heat storage material is provided within the flow path.

5. 3. The magnetocaloric material bed according to claim 1, wherein the heat storage material is provided on a bed wall that defines the flow path.

6. 3. The magnetocaloric material bed according to claim 1, wherein the heat storage material is encapsulated.

7. 3. The magnetocaloric material bed according to claim 1, wherein the heat storage material is covered with a magnetocaloric material capsule formed by the magnetocaloric material.

8. 3. The magnetocaloric material bed according to claim 1, wherein the heat storage material is a latent heat storage material that stores heat when undergoing a phase transition from solid to solid.

9. a magnetocaloric material bed according to claim 1 or 2; a magnetic field modulation device configured to be able to vary a magnetic field applied to the magnetocaloric material bed having the flow path in which the magnetocaloric material is provided; a high temperature side heat exchanger connected to the magnetocaloric material bed; a low-temperature heat exchanger connected to the magnetocaloric material bed on the opposite side of the high-temperature heat exchanger; a pump configured to transport a heat exchange fluid between the high-temperature side heat exchanger and the low-temperature side heat exchanger via the magnetocaloric material bed; A magnetic refrigeration device comprising:

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