Particle structure, bed structure, module, magnetic refrigeration device, and method for manufacturing particle structure

Abstract

To provide a particle structure, a bed structure, a module and a magnetic refrigeration device that improve performance.SOLUTION: A particle structure (1) is a particle structure used in a magnetic refrigeration device (100) and includes particles (11) and a coating (12). The particles (11) have a magnetocaloric effect. The coating (12) covers a portion of the surface (11a) of the particles (11). The thermal conductivity of the coating (12) is lower than the thermal conductivity of the particles (11). The coating (12) has a constant thickness along the surface (11a).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a particle structure, a bed structure, a module, and a magnetic refrigerator. [Background technology]

[0002] Active magnetic refrigeration (AMR) type magnetic refrigeration devices have been known as an environmentally friendly refrigeration technology. As disclosed in Patent Document 1 (JP 2016-530479 A), AMR type magnetic refrigeration devices have a bed structure including a bed as a container and particles having a magnetocaloric effect packed in the bed. Paragraph

[0050] of Patent Document 1 discloses that most of the particles are in contact with each other. Summary of the Invention [Problem to be solved by the invention]

[0003] However, in the technology disclosed in Patent Document 1, most of the particles are in contact with each other, so heat conduction between the particles cannot be suppressed. As a result, the temperature difference between both ends of the bed structure is suppressed, and the magnetic refrigeration device cannot achieve sufficient performance. [Means for solving the problem]

[0004] A particle structure according to a first aspect is a particle structure for use in a magnetic refrigeration device, and comprises particles and a coating. The particles have a magnetocaloric effect. The coating covers a portion of the surface of the particles. The thermal conductivity of the coating is lower than the thermal conductivity of the particles. The coating has a constant thickness along the surface.

[0005] According to the particle structure of the first aspect, a coating having a thermal conductivity lower than that of the particles is formed on a portion of the particle surface. Therefore, when the particle structure of the first aspect is used in a magnetic refrigeration device, heat conduction between particles can be suppressed in the direction of movement of a fluid passing through a flow path. This increases the temperature difference between the particles at both ends of the bed structure. Therefore, heat exchange between the fluid and the particles can be promoted, thereby improving the performance of a magnetic refrigeration device using the particle structure of the first aspect.

[0006] A particle structure according to a second aspect is the particle structure according to the first aspect, wherein the coating contains at least one resin selected from the group consisting of a thermosetting resin, a thermoplastic resin, and a photocurable resin.

[0007] As in the particle structure of the second aspect, a coating containing at least one of a thermosetting resin, a thermoplastic resin, and a photocurable resin may be used.

[0008] A particle structure according to a third aspect is the particle structure according to the second aspect, wherein the resin contains at least one of an epoxy resin, a melamine resin, a phenolic resin, a fluororesin, a polyethylene resin, and a polypropylene resin.

[0009] As in the particle structure of the third aspect, a resin containing at least one of epoxy resin, melamine resin, phenol resin, fluororesin, polyethylene resin, and polypropylene resin may be used.

[0010] A particle structure according to a fourth aspect is the particle structure according to the first aspect, wherein the coating contains an inorganic adhesive.

[0011] As in the particle structure of the fourth aspect, a coating containing an inorganic adhesive may be used.

[0012] A particle structure according to a fifth aspect is the particle structure according to any one of the first aspect to the fourth aspect, wherein the particles have a spherical shape.

[0013] In the particle structure of the fifth aspect, spherical particles are used, so the particles can be densely packed in the bed, which eliminates the need for a binder to bond multiple particles together.

[0014] A bed structure according to a sixth aspect includes a plurality of particle structures according to any one of the first to fifth aspects, wherein flow paths through which a fluid passes are formed between the particles.

[0015] In the bed structure of the sixth aspect, heat conduction between particles can be suppressed, so that the temperature difference between the particles at both ends can be increased, which can further promote heat exchange between the fluid and the particles, thereby improving the performance of the bed structure.

[0016] A module according to a seventh aspect includes a plurality of bed structures according to the sixth aspect, wherein the particles constituting the plurality of bed structures have different magnetocaloric effects.

[0017] In the module of the seventh aspect, since heat conduction between particles with different magnetocaloric effects can be suppressed, the temperature difference between the particles can be increased, which can further promote heat exchange between the fluid and the particles, thereby improving the performance of the module.

[0018] A magnetic refrigeration apparatus according to an eighth aspect includes a module, an application unit, and a movement unit. The module is the module according to the seventh aspect. The application unit applies a magnetic field to the particles. The movement unit moves a fluid that exchanges heat with the particles.

[0019] In the magnetic refrigeration device of the eighth aspect, the fluid heated by heat exchange with the particles can be moved by the moving part to extract hot heat, and the fluid that has absorbed heat by heat exchange with the particles can be moved by the moving part to extract cold heat. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram of a particle structure according to an embodiment of the present disclosure. [Figure 2]FIG. 1 is a schematic diagram of a bed structure according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is an enlarged schematic view of the bed structure. [Figure 4] 1 is a flowchart illustrating a method for manufacturing a particle structure and a bed structure. [Figure 5] FIG. 1 is a schematic diagram of a particle. [Figure 6] FIG. 2 is a schematic diagram showing a process of forming a coating on a part of the surface of a particle. [Figure 7] FIG. 4 is a schematic diagram in which the flow of fluid is added to FIG. 3. [Figure 8] FIG. 1 is a schematic diagram of a module according to an embodiment of the present disclosure. [Figure 9] FIG. 1 is a schematic diagram of a heat source according to an embodiment of the present disclosure. [Figure 10] 1 is a schematic configuration diagram of a magnetic refrigeration device according to an embodiment of the present disclosure. [Figure 11] FIG. 10 is a diagram showing the thermal conductivity and the temperature difference between both ends in a bed structure. [Figure 12] 10A to 10C are schematic diagrams showing a manufacturing method of a bed structure according to a modified example. [Figure 13] FIG. 10 is a schematic diagram of a bed structure according to a modified example. [Figure 14] FIG. 1 is a diagram showing condition A of Example 1. [Figure 15] FIG. 10 is a diagram showing condition B of Example 1. [Figure 16] FIG. 10 is a diagram illustrating the thermal resistance of heat conduction between particles in Example 2. [Figure 17] FIG. 10 is a diagram for explaining the thermal resistance of heat transfer by a fluid in the second embodiment. [Figure 18] FIG. 10 is a diagram showing a model A of the magnetic field change process in Example 2. [Figure 19] FIG. 10 is a diagram showing a model B of the magnetic field change process in Example 2. [Figure 20] FIG. 10 is a diagram showing a model C of the magnetic field change process in Example 2. [Figure 21] FIG. 10 is a diagram showing a model of the flow change process in Example 2. [Figure 22]10 is a graph showing the results when the particle size is 200 μm in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, a particle structure, a bed structure, a module, a heat source, and a magnetic refrigeration device according to an embodiment of the present disclosure will be described with reference to examples.

[0022] (1) Particle structure The particle structure of this embodiment is used in an active magnetic refrigeration type magnetic refrigeration device. The particle structure includes particles and a coating. The particles have a magnetocaloric effect. The coating covers a portion of the surface of the particles. The thermal conductivity of the coating is lower than the thermal conductivity of the particles. The coating has a constant thickness along the surface of the particles.

[0023] Such a particle structure can be configured, for example, as a particle structure 1 shown in Fig. 1. As shown in Fig. 1, the particle structure 1 of this embodiment includes a particle 11 and a coating 12.

[0024] The particles 11 can be used to cool or heat an object whose temperature is to be controlled by changing the magnetic entropy to obtain a magnetocaloric effect. The particles 11 generate heat when a magnetic field is applied, and absorb heat when the application of the magnetic field is stopped and the magnetic field is removed.

[0025] The particles 11 are not limited as long as they have a magnetocaloric effect. Here, the particles 11 are a magnetic working material having a Curie temperature, which is a phase transition temperature. Examples of such particles 11 include NaZn 13 Materials with structure (La-Fe-Si based materials), MnAs 1-x Sb x Examples include:

[0026] The particles 11 have a spherical shape, which means a shape without any sharp edges.

[0027] The particles 11 are fine particles. Specifically, the particle diameter of the particles 11 is, for example, 50 μm or more and 500 μm or less.

[0028] The coating 12 is provided on a part of the surface 111 of the particle 11 in order to suppress heat conduction between the particles 11. Specifically, the coverage ratio of the coating 12 to the surface area of ​​the particle 11 is preferably 10% or more, and more preferably 20% or more.

[0029] Furthermore, the coating 12 is not provided on the entire surface 111 of the particle 11 in order to transfer heat from the particle 11 to the fluid. Specifically, the coverage ratio of the coating 12 to the surface area of ​​the particle 11 is, for example, 98% or less, and preferably 80% or less.

[0030] The coating 12 has a thermal conductivity lower than that of the particles 11. Such a coating 12 has, for example, insulating properties and is specifically made of a resin, an adhesive, or the like. The coating 12 made of a resin includes at least one of a thermosetting resin, a thermoplastic resin, and a photocurable resin. More specifically, the resin includes at least one of an epoxy resin, a melamine resin, a phenolic resin, a fluororesin, a polyethylene resin, and a polypropylene resin. The coating 12 made of an adhesive includes an inorganic adhesive. More specifically, the inorganic adhesive is a ceramic adhesive, an adhesive containing a metal oxide, or the like.

[0031] The coating 12 is formed along the surface 111 of the particle 11. In other words, the outer periphery of a portion of the surface 111 and the inner and outer peripheries of the coating 12 have the same shape. In Fig. 1, the coating 12 is continuous with the surface 111 of the particle 11 and has a fan shape.

[0032] The coating 12 has a constant thickness. A constant thickness includes a case where the thickness is considered to be substantially the same. For example, a case where the ratio of the maximum thickness to the minimum thickness is 1.3 or less.

[0033] Specifically, the thickness of the coating 12 is preferably, for example, 10 μm or more, and more preferably 20 μm or more. The thickness of the coating 12 is smaller than the particle diameter of the particles 11.

[0034] In this embodiment, the ratio of the mass of the coating 12 to the mass of the particle 11 (coating 12 / particle 11) is less than 10%.

[0035] (2) Bed structure (2-1) Overview The bed structure comprises a plurality of particle structures, with channels formed between the particles for the passage of a fluid.

[0036] Such a bed structure can be configured, for example, as a bed structure 10 shown in Figures 2 and 3. As shown in Figures 2 and 3, the bed structure 10 of this embodiment includes a plurality of particles 11 and a coating 12 that coats the surface 111 of each particle 11.

[0037] The bed structure 10 has a structure in which heat conduction between particles 11 is suppressed by the coating 12. This structure is configured so that heat conduction between particles 11 is suppressed by the coating 12 in the direction of movement of the fluid flowing through the bed structure 10. Here, the coating 12 is solidified on a part of the surface 111 of the particles 11, and does not bond the particles 11 together. Therefore, the bed structure 10 does not include a binder for bonding multiple particles 11 together.

[0038] The particles 11 may be in contact with the coating 12 or with the particles 11. Specifically, in the bed structure 10, a first particle structure 1 and a second particle structure 1 are adjacent to each other. There are cases where the particles 11 of the first particle structure 1 are in contact with the particles 11 of the second particle structure 1, where the coating 12 of the first particle structure 1 is in contact with the coating 12 of the second particle structure 1, where the particles 11 of the first particle structure 1 are in contact with the coating 12 of the second particle structure 1, and where the coating 12 of the first particle structure is in contact with the particles 11 of the second particle structure 1.

[0039] A gap is provided between the particle 11 and the coating 12, and the gap forms a flow path 14 through which a fluid passes. Since a part of the surface 111 of the particle 11 is exposed, the fluid passing through the flow path 14 exchanges heat with the particle 11.

[0040] As shown in Fig. 2, the bed structure 10 further includes a bed 13 that accommodates a plurality of particle structures 1. Here, the bed 13 accommodates particles 11 of the same composition. In other words, the bed 13 accommodates one type of particle 11. The bed 13 of this embodiment constitutes a module 20 (see Fig. 8), a heat source 2 (see Fig. 9), and a magnetic refrigeration device 100 (see Fig. 10), which will be described later.

[0041] Bed 13 is a hollow packed tank. Bed 13 has a surface 131 through which a fluid passes and a surface 132 through which the fluid does not pass. Pores smaller than particles 11 are formed in surface 131 through which the fluid passes. No pores are formed in surface 132 through which the fluid does not pass.

[0042] (2-2) Manufacturing method Hereinafter, a method for producing the particle structure shown in FIG. 1 and the bed structure 10 shown in FIGS. 2 and 3 will be described with reference to FIGS.

[0043] First, a plurality of particles 11 are prepared as shown in Fig. 4 (step S1). The particles 11 have a magnetocaloric effect. Here, spherical particles 11 are prepared as shown in Fig. 5.

[0044] Next, the coating 12 is formed on a part of the surface 111 of the particle 11 (step S2). This step (S2) is performed, for example, as follows.

[0045] Specifically, as shown in FIG. 6, a plate-shaped pallet P is prepared. Multiple holes P1 smaller than the particle size of the particles 11 are formed in the pallet P. The pallet P has a mesh-like structure. The particles 11 are then placed over each hole P1. Then, the particles 11 are fixed by suction from below the pallet P. The arrows in FIG. 6 indicate the direction of suction. The suction method is not particularly limited, and for example, magnetic force from a magnet is used. In this state, a material that will become the coating 12 is applied to at least a portion of the surface 111 of the particles 11 exposed above the holes P1. The application method is not particularly limited, and for example, brush application, spray application, application using a paint roller, pad printing, application using a curtain coater, electrostatic application, etc. are used. The applied material is then solidified to form the coating 12. This allows multiple particle structures 1 to be produced. Once the formation of the coating 12 is complete, the suction is stopped, and the multiple particle structures 1 can be collected.

[0046] Next, a plurality of particle structures 1 are packed into the bed 13 (step S3). Here, the bed 13 packed with the particle structures 1 is rocked to increase the packing rate of the particle structures 1. By carrying out the above steps (S1 to S3), the bed structure 10 can be manufactured.

[0047] The amount of coating 12 applied to particle 11 is controlled by adjusting the size of hole P1 in pallet P to adjust the surface area of ​​particle 11 exposed through hole P1, or by adjusting the amount of coating 12 applied.

[0048] (2-3) How to confirm the heat conduction suppression effect of the coating Heat is applied to one surface 131 of the bed 13 packed with the particle structure 1 of this embodiment, and the temperature of the opposite surface 131 is measured. The temperature difference is larger than that of the bed 13 packed with particles 11 on which the coating 12 is not formed, so the degree to which the coating 12 has suppressed heat conduction between the particles 11 can be confirmed.

[0049] (2-4) Operation The operation of the bed structure 10 of this embodiment will be described with reference to Figure 7. The arrows in Figure 7 indicate the flow of fluid.

[0050] As shown in Fig. 7, a fluid passes through the flow path 14 of the bed structure 10 of this embodiment. The fluid flows while exchanging heat with the particles 11 exposed from the coating 12. When the particles 11 generate heat due to the application of a magnetic field, or absorb heat due to the cessation of the application of the magnetic field, the fluid is heated or cooled by the particles 11.

[0051] (3) Module The module includes a plurality of bed structures. The module has at least two bed structures arranged side by side. The shape and arrangement of the module are not particularly limited.

[0052] Such a module can be configured, for example, as a module 20 shown in Fig. 8. As shown in Fig. 8, the module 20 of this embodiment includes a first bed structure 10a, a second bed structure 10b, a third bed structure 10c, a fourth bed structure 10d, and a fifth bed structure 10e. The first to fifth bed structures 10a to 10e are the bed structures (2) above, and include particles 11a to 11e, resins 12a to 12e, and beds 13a to 13e. The flow paths of the bed structures 10a to 10e are connected to each other.

[0053] The particles 11a to 11e constituting the bed structures 10a to 10e are different from one another. In other words, the module 20 has multiple types of particles 11a to 11e. The particles 11a of the first bed structure 10a, the particles 11b of the second bed structure 10b, the particles 11c of the third bed structure 10c, the particles 11d of the fourth bed structure 10d, and the particles 11e of the fifth bed structure 10e are made of materials with decreasing Curie temperatures in this order. In other words, the particles 11a of the first bed structure 10a, the particles 11b of the second bed structure 10b, the particles 11c of the third bed structure 10c, the particles 11d of the fourth bed structure 10d, and the particles 11e of the fifth bed structure 10e are arranged in order of decreasing Curie temperatures.

[0054] (4)Heat source The heat source of this embodiment utilizes heat released from the particles to exchange heat with the fluid. The heat source includes the bed structure described above in (2) and an application unit. Here, the heat source includes the module described above in (3) and an application unit. Therefore, the heat source includes multiple types of particles with different magnetocaloric effects.

[0055] The application unit applies a magnetic field to the particles. Specifically, the application unit is capable of changing the magnetic field applied to the particles. The application unit has a magnetic circuit or the like, and has a portion located on one side and a portion located on the other side with respect to the plurality of types of particles.

[0056] The application unit can switch between a state in which a magnetic field is applied to the particles and a state in which a magnetic field is not applied to the particles. The application unit may also be capable of performing a process of strengthening the magnetic field applied to the particles and a process of weakening the magnetic field without reducing it to zero.

[0057] Such a heat source can be configured, for example, as a heat source 2 shown in FIG.

[0058] 8, the module 20 has a plurality of bed structures 10a to 10e arranged side by side. The application unit 30 has a portion located on one side of the module 20 and a portion located on the other side, and can apply a magnetic field to the module 20, and can also stop applying the magnetic field and remove the magnetic field.

[0059] (5) Magnetic Refrigeration Device The magnetic refrigeration device of this embodiment is an AMR type. The magnetic refrigeration device includes the module (3), an application unit, and a moving unit. Here, the magnetic refrigeration device includes the heat source (4) and a moving unit.

[0060] The moving part moves a fluid that exchanges heat with the particles. The fluid is in thermal contact with the particles. The fluid is, for example, a heat medium such as a refrigerant or water.

[0061] Specifically, the moving unit moves the fluid relative to the plurality of types of particles contained in the module. The moving unit is not particularly limited, and may be configured by pistons provided on both sides of the particles, or may be configured by a pump provided in a closed circuit.

[0062] Such a magnetic refrigeration device can be configured, for example, as a magnetic refrigeration device 100 shown in Fig. 10. The magnetic refrigeration device 100 here is a temperature control device. The magnetic refrigeration device 100 includes a heat source 2, a transfer circuit 60, a high-temperature side circuit 40, and a low-temperature side circuit 50.

[0063] As described above, the heat source 2 has the module 20 and the application unit 30. As described in (3) above, the module 20 has a plurality of the bed structures 10a to 10e shown in Fig. 2, as shown in Fig. 8. The application unit 30 can apply a magnetic field to all of the first to fifth particles 11a to 11e included in the plurality of bed structures 10a to 10e, and can remove the magnetic field by weakening or stopping the applied magnetic field.

[0064] The transfer circuit 60 includes a tank 62, a pump 63, and a flow path 61 connecting these, and is filled with a fluid. The bed structures 10a-10e may be disposed inside the tank 62, or may be disposed outside the tank 62 so that the fluid inside the tank 62 and the particles 11a-11e are in thermal contact with each other. The tank 62 includes a high-temperature reservoir 62a on the high-temperature side relative to the module 20 and a low-temperature reservoir 62b on the low-temperature side relative to the module 20. In the module 20, the particles 11e with a high Curie temperature are located on the high-temperature reservoir 62a side, and the particles 11a with a low Curie temperature are located on the low-temperature reservoir 62b side. When a magnetic field is applied from the application unit 30 to the module 20 and the fluid is heated by heat radiated from the module 20, the pump 63 is driven to transfer the fluid to the high-temperature side relative to the module 20. As a result, the high-temperature fluid is stored in the high-temperature reservoir 62a. Furthermore, when the application unit 30 stops applying the magnetic field to the module 20 and removes the magnetic field, the module 20 absorbs heat from the fluid, and when the temperature of the fluid drops, the pump 63 is driven to move the fluid to the low-temperature side of the module 20. As a result, the low-temperature fluid is stored in the low-temperature storage unit 62b. By repeating the above-described movement of the fluid and the application and removal of the magnetic field, the high-temperature fluid is collected in the high-temperature storage unit 62a, and the low-temperature fluid is collected in the low-temperature storage unit 62b.

[0065] The high-temperature side circuit 40 includes a high-temperature side first heat exchanger 41, a high-temperature side pump 44, a high-temperature side second heat exchanger 42, and a high-temperature side flow path 43 connecting these elements. A high-temperature side heat medium, such as a refrigerant or water, circulates through the circuit. The high-temperature side first heat exchanger 41 is disposed within the high-temperature reservoir 62a and exchanges heat between the high-temperature side heat medium flowing through the high-temperature side first heat exchanger 41 and the high-temperature fluid in the high-temperature reservoir 62a. The high-temperature side second heat exchanger 42 uses the high temperature of the high-temperature side heat medium flowing through it to heat an object to be temperature-controlled. The object to be temperature-controlled may be air, a fluid such as water, or a solid to be heated. The high-temperature side flow path 43 connects the high-temperature side first heat exchanger 41, the high-temperature side pump 44, and the high-temperature side second heat exchanger 42 so that the high-temperature side heat medium can circulate between them. The high-temperature side pump 44 circulates the high-temperature side heat medium in the high-temperature side circuit 40 when driven.

[0066] The low-temperature side circuit 50 includes a first low-temperature side heat exchanger 51, a low-temperature side pump 54, a second low-temperature side heat exchanger 52, and a low-temperature side flow path 53 connecting these components. A low-temperature side heat medium, such as a refrigerant or water, circulates through the circuit. The first low-temperature side heat exchanger 51 is provided in the low-temperature reservoir 62b and performs heat exchange between the low-temperature side heat medium flowing through the first low-temperature side heat exchanger 51 and the low-temperature fluid in the low-temperature reservoir 62b. The second low-temperature side heat exchanger 52 uses the low temperature of the low-temperature side heat medium flowing through it to cool an object to be temperature-controlled. The object to be temperature-controlled may be air, a fluid such as water, or a solid to be cooled. The low-temperature side flow path 53 connects the first low-temperature side heat exchanger 51, the low-temperature side pump 54, and the second low-temperature side heat exchanger 52 so that the low-temperature side heat medium can circulate between them. The low-temperature side pump 54 circulates the low-temperature side heat medium within the low-temperature side circuit 50 when driven.

[0067] (6) Features (6-1) The particle structure 1 according to this embodiment is a particle structure used in a magnetic refrigeration device 100, and includes a particle 11 and a coating 12. The particle 11 has a magnetocaloric effect. The coating 12 covers a part of a surface 111 of the particle 11. The thermal conductivity of the coating 12 is lower than the thermal conductivity of the particle 11. The coating 12 has a constant thickness along the surface 111.

[0068] According to the particle structure 1 of this embodiment, a coating 12 having a thermal conductivity smaller than that of the particle 11 is formed on a portion of the surface 111 of the particle 11. Therefore, when the particle structure 1 of this embodiment is used in the bed structure 10, the module 20, and the magnetic refrigeration device 100, heat conduction between the particles 11 can be suppressed in the direction of movement of the fluid passing through the flow path 14. Therefore, as shown in FIG. 11 , the temperature difference between the particles 11 can be increased at both ends of the bed structure 10 including a plurality of particle structures 1. Therefore, heat exchange between the particles 11 and the fluid flowing from one end to the other end of the bed structure 10 can be promoted, thereby improving the performance of the bed structure 10, the module 20, and the magnetic refrigeration device 100 using the particle structure 1 of this embodiment.

[0069] The bed structure 10 of this embodiment can increase the temperature difference between both ends of the bed structure compared to a bed structure in which magnetocaloric particles are packed into a metal sheath (Comparative Example 1), a bed structure in which the particles are sintered (Comparative Example 2), and a bed structure in which a flow path is formed by machining (Comparative Example 3). Specifically, in Comparative Example 1, the temperature difference between both ends of the bed structure is reduced due to thermal conduction through the metal sheath. Furthermore, even when the metal sheaths are in contact with each other, thermal conduction occurs, reducing the temperature difference between both ends of the bed structure. In Comparative Example 2, the sintered body obtained by sintering particles has excellent thermal conductivity, reducing the temperature difference between both ends of the bed structure. In Comparative Example 3, even when a flow path is formed by processing a metal ingot having a magnetocaloric effect after its production, the temperature difference between both ends of the bed structure is reduced due to the thermal conduction of the metal itself. Thus, while the particles are in contact throughout the entirety in Comparative Examples 1 to 3, this embodiment achieves a structure in which thermal conduction between the particles 11 is suppressed.

[0070] (6-2) The particle structure 1 according to this embodiment is the particle structure according to the above (6-1), in which the coating 12 contains at least one resin selected from the group consisting of a thermosetting resin, a thermoplastic resin, and a photocurable resin.

[0071] In this way, the coating 12 may include at least one of a thermosetting resin, a thermoplastic resin, and a photocurable resin.

[0072] (6-3) The particle structure according to this embodiment is the particle structure according to (6-2) above, wherein the resin contains at least one of epoxy resin, melamine resin, phenol resin, fluororesin, polyethylene resin, and polypropylene resin.

[0073] In this way, the coating 12 may contain at least one of epoxy resin, melamine resin, phenol resin, fluororesin, polyethylene resin, and polypropylene resin.

[0074] (6-4) The particle structure 1 according to this embodiment is the particle structure according to the above (6-3), in which the coating 12 contains an inorganic adhesive.

[0075] In this way, a coating 12 containing an inorganic adhesive may be used.

[0076] (6-5) The particle structure 1 according to this embodiment is a particle structure according to any one of the above (6-1) to (6-4), in which the particles 11 have a spherical shape.

[0077] Here, spherical particles 11 are used, so the particles 11 can be densely packed in the bed 13. This eliminates the need for a binder to bond multiple particles 11. As such, the coating 12 of this embodiment is not intended to bond multiple particles 11, but rather to suppress heat conduction between the particles 11.

[0078] (6-6) The bed structure 10 according to this embodiment includes a plurality of particle structures 1 according to any one of the above (6-1) to (6-5). Between the particles 11, a flow path 14 is formed through which a fluid passes.

[0079] Here, since the bed structure 10 includes a plurality of particle structures 1, heat conduction between the particles 11 can be suppressed, and the temperature difference between the particles 11 at both ends can be increased. This further promotes heat exchange between the fluid and the particles 11, thereby improving the performance of the bed structure 10.

[0080] Furthermore, by packing the particle structure 1 into the bed 13, the proportion of the coating 12 can be controlled, and therefore, variations in the coating 12 in the bed structure 10 can be suppressed.

[0081] (6-7) The module 20 according to this embodiment includes a plurality of bed structures 10 according to (6-6) above. The particles 11a to 11e constituting the plurality of bed structures 10a to 10e have different magnetocaloric effects.

[0082] Here, since the plurality of particle structures 1 are provided, heat conduction between the particles 11a-11e with different magnetocaloric effects can be suppressed, and the temperature difference between the particles 11a-11e (each of the bed structures 10a-10e) can be increased, which further promotes heat exchange between the particles 11a-11e and the fluid, thereby improving the performance of the module 20.

[0083] (6-8) The magnetic refrigeration device 100 according to this embodiment includes a module 20, an application unit 30, and a pump 63 as a movement unit. The module 20 is the module according to (6-7) above. The application unit 30 applies a magnetic field to the particles 11. The pump 63 as a movement unit moves a fluid that exchanges heat with the particles 11.

[0084] Here, the fluid heated by heat exchange with the particles 11 can be moved by the pump 63 as a moving part to extract hot heat, and the fluid that has absorbed heat by heat exchange with the particles 11 can be moved by the pump 63 as a moving part to extract cold heat.

[0085] (6-9) The method for manufacturing the bed structure 10 according to this embodiment is a method for manufacturing the bed structure (6-6) described above. The method for manufacturing the bed structure 10 includes a step (S2) of forming a coating on a part of the surface 111 of the particle 11 to manufacture the particle structure 1, and a step (S3) of filling the particle structure 1 into the bed 13.

[0086] Here, after the particle structure 1 is produced, it is packed into the bed 13, so that the time required for molding into a predetermined shape can be shortened and the bed structure 10 can be produced.

[0087] Furthermore, the particle structure 1 and bed structure 10 of this embodiment can be produced without using a solvent, which reduces the environmental load and facilitates mass production of the bed structure 10.

[0088] (6-10) In the manufacturing method of the bed structure 10 of this embodiment, in the manufacturing method of the bed structure of (6-9) above, the step (S2) of manufacturing the particle structure 1 includes a step of arranging a plurality of particles 11 on one surface, and a step of applying a material to become the coating 12 to a portion of the surface 111 of the arranged particles 11 and solidifying it.

[0089] By producing in this manner, a plurality of particle structures 1 can be produced efficiently.

[0090] (6-11) In the manufacturing method of the bed structure 10 according to this embodiment, in the manufacturing method of the bed structure (6-10) above, the particles 11 are spread all over the pallet P in the step of arranging the particles 11 on one surface.

[0091] In this way, by using the pallet P having holes P1 smaller than the particles 11, the coating 12 can be easily formed.

[0092] (6-12) The manufacturing method of the bed structure 10 according to this embodiment is a manufacturing method of a bed structure according to any one of (6-9) to (6-11) above, in which in the step (S2) of manufacturing the particle structure 1, a coating 12 is formed on a portion of the surface 111 of the particle 11 by brush coating, spray coating, coating using a coating roller, pad printing, coating using a curtain coater or electrostatic coating.

[0093] By such a method, the coating 12 may be formed on a part of the surface 111 of the particle 11 .

[0094] (7) Variations (7-1) Variation 1 In the above embodiment, the bed structure manufacturing method is described by taking as an example a method in which the particle structure 1 is filled into the bed 13 (S3) and then rocked, but is not limited to this. In this modified example, the bed structure is manufactured as follows.

[0095] Specifically, as shown in FIG. 6, after forming the coating 12 on the particles 11, the particle structure 1 is sucked through the hole P1 in the pallet P, and the pallet P is then turned upside down as shown in FIG. 12. Note that the arrow in FIG. 12 indicates the suction direction. Alternatively, a second pallet (not shown) may be placed on top of the coating 12, and the particle structure 1 may be sucked from above using the second pallet. Then, suction is stopped above the bed 13. This causes multiple particle structures 1 to fall into the bed 13, forming a single layer in which the positions of the coatings 12 on the particle structures 1 are aligned. This process is repeated to form multiple layers, as shown in FIG. 13. In this modification, the orientation of the coatings 12 on the particle structures 1 is aligned, thereby suppressing thermal conduction of the particles 11 in the bed 13 in the vertical direction and facilitating thermal conduction in the horizontal direction. This suppresses thermal conduction between the particles 11 in the fluid flow direction.

[0096] (7-2) Variation 2 In the above embodiment, the particles 11 are arranged on a surface by spreading the particles 11 on the pallet P, but this is not limiting. In this modified example, the particles 11 are arranged on a surface by continuously flowing the particles 11 without using a pallet.

[0097] (7-3) Variation 3 In the above embodiment, the coating 12 is formed in one place on the surface 111 of the particle 11, but this is not limiting. In this modification, the coating 12 is scattered on the surface 111 of the particle 11.

[0098] (7-4) Variation 4 In the above embodiment, the spherical particles 11 are used as an example, but the shape of the particles is not limited to this. The shape of the particles may be crushed powder, pellets, or the like.

[0099] (7-5) Variation 5 In the above embodiment, the module 20, the heat source 2, and the magnetic refrigeration device 100 include, but are not limited to, two or more types of particles 11. The heat source and the magnetic refrigeration device of the present disclosure may include one type of particle. [Example]

[0100] Example 1 In Example 1, the effect of providing a coating that covers part of the surface of the particles was examined.

[0101] The temperature difference between particles was calculated for the following cases: (Condition A) as shown in Figure 14, where a resin coating of 10 μm thickness was applied to part of the particle surface; and (Condition B) as shown in Figure 15, where particles were in direct contact with each other and fluid was present between them to the extent of the surface roughness (1 μm thickness).

[0102] The calculation conditions were steady (no change over time) and one-dimensional (temperature distribution only in the thickness direction), with no internal heat generation (resin and fluid do not generate heat), and only the particles on one side (x=0) of the resin or fluid always generate heat, with the surface temperature of that side (x=0) of the resin or fluid being constant. In this case, by solving the heat conduction equation expressed in Equation 1 below, it can be seen that the temperature difference is inversely proportional to the thermal conductivity k of the material (resin and fluid) between the particles and proportional to the thickness x. T(x)=-Q / S x / k+T(0) (Formula 1)

[0103] In Equation 1, T(x) is the temperature (K), Q is the amount of heat generated (W), and S is the cross-sectional area (m 2 ) and k is the thermal conductivity (W / mK).

[0104] Here, condition A used epoxy resin (thermal conductivity k = 0.30 (W / mK)), and condition B used liquid water (thermal conductivity k = 0.6 (W / mK)) as the fluid, with the calorific value calculated as 0.01 (W). As a result, x / k in equation 1 for condition A was 20 times that of condition B. In this way, it was found that the temperature difference between particles in condition A, which has a resin coating, was more than 20 times greater than that in condition B, which had no coating, and therefore heat transfer by the resin was inhibited.

[0105] Example 2 In Example 2, a preferable range of the coating ratio of the coating to the particles was investigated.

[0106] <Evaluation method> The magnetic refrigeration cycle of the magnetic refrigeration device described in (5) above consists of (i) a magnetic field change process and (ii) a flow change process. In the (i) magnetic field change process, the fluid in the bed is stationary during the application or removal of the magnetic field, and it is important to maintain the temperature difference between the particles. In the (ii) flow change process, the fluid is made to flow while maintaining the magnetic field, transporting the heat of the particles, so it is important to increase the amount of heat exchange between the particles and the fluid.

[0107] Here, the thermal resistance R of heat conduction between particlesth1 is expressed by the following equation 2 in the model of FIG. Thermal resistance R th1 = length L / (thermal conductivity λ × cross-sectional area A) (Equation 2)

[0108] The temperature difference between particles (T1-T2) is expressed by the following formula 3. Temperature difference (T1-T2) = thermal resistance R th1 ×Heat flow rate P (Formula 3)

[0109] (i) In the magnetic field change process, the larger the thermal resistance between particles, the larger the temperature difference between particles. Therefore, from Equation 3, the thermal resistance R in Equation 2 th1 It can be seen that the larger is the more desirable.

[0110] On the other hand, the thermal resistance of heat transfer through the fluid R th2 is expressed by the following equation 4 in the model of FIG. Thermal resistance R th2 = 1 / (convective heat transfer coefficient hm × surface area B) (Equation 4)

[0111] The difference between the surface temperature and the fluid temperature, which is the thermal resistance between the particle and the fluid, is expressed by the following equation 5. (Surface temperature - Fluid temperature) = Thermal resistance R th2 ×Heat flow rate P (Formula 5)

[0112] (ii) In the flow change process, it is desirable to increase the amount of heat exchange. Therefore, from Equation 5, the thermal resistance R in Equation 4 is th2 It can be seen that the smaller is the more desirable.

[0113] The thermal resistance is a value expressed as a linear function. Therefore, the present inventors have calculated the effect of the coating amount on the thermal resistance for the magnetic refrigeration cycle processes (i) and (ii) by using the following equation 6: th2 R th1 The ratio (R th1 / R th2 ) was used as the evaluation function δ. Evaluation function δ=R th1 / Rth2 ...(Formula 6)

[0114] As mentioned above, R th1 The larger the value, the better. th2 Since a smaller value of the evaluation function δ is desirable, a larger value of the evaluation function δ indicates a better balance between heat transfer and heat conduction.

[0115] <Calculating thermal resistance> (i) When calculating the magnetic field change process, a model was considered to calculate the thermal resistance between the centers of two particles 11, as shown in Figures 18 to 20. The following explanation assumes that the particles 11 are spherical iron and the coating 12 is resin. Model A in Figure 18 is the case when both resins are present between the particles, Model B in Figure 19 is the case when only one resin is present between the particles, and Model C in Figure 20 is the case when there is no resin between both particles. Resin adhesion to the particles is assumed to be point symmetric, and only the areas surrounded by dotted lines in the figures were calculated.

[0116] In the case of Model A, there are five heat exchange paths, as shown by the arrows in the figure: particle-coating-coating-particle, particle-coating-fluid-coating-particle, particle-coating-fluid-particle, particle-fluid-coating-particle, and particle-fluid-particle. The thermal resistance R th1 was calculated from Equation 2, and the five heat exchange paths were added in series to calculate the combined resistance in parallel. The same calculation was performed for Model B and Model C. The combined resistance value at this time was taken as the thermal resistance during the magnetic field change process (i).

[0117] Next, (ii) when calculating the flow change process, a model was considered to calculate the thermal resistance value from the center of the particle to the fluid, as shown in Figure 21. In this case, there are two heat exchange paths: particle-coating-fluid and particle-fluid. The respective thermal resistances R th2 was calculated from Equation 4, and the combined resistance at this time was calculated in the same manner as above, and this was taken as (ii) the thermal resistance during the flow change process.

[0118] The following values ​​were used as constants in the calculations: Particle diameter: 200 μm Thermal conductivity of iron as particles: 10 W / (m K) Thermal conductivity of resin as coating: 0.3 W / (m K) Water as a fluid (at rest) Fluid heat transfer coefficient: 100 W / (m 2 ·K) Water as a fluid (forced convection) Fluid heat transfer coefficient: 30000 W / (m 2 ·K)

[0119] The results when the particle diameter of the particle 11 is 200 μm and the thickness of the coating 12 is 30 μm and 40 μm are shown in Figure 22. In Figure 22, the vertical axis represents the value of the evaluation function δ, and the horizontal axis represents the proportion of the coating covering the particle surface.

[0120] <Evaluation results> As shown in Figure 22, it was found that for each coating thickness, the heat conduction between particles can be reduced and the heat transfer between the material and the fluid can be improved compared to when the coating coverage is 0%. It was also found that an optimal value for the evaluation function δ exists for the coverage of a coating with a constant thickness along the particle surface. Figure 22 shows that the coverage of the coating relative to the particle surface area is preferably 10% to 98%, and more preferably 20% to 80%.

[0121] The inventors have found that similar results are obtained when the coating thickness is 5 μm to 20 μm, and also when the particle diameter is 100 μm.

[0122] Although the embodiments and examples of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0123] 1: Particle structure 10, 10a, 10b, 10c, 10d, 10e: Bed structure 11,11a,11b,11c,11d,11e: Particle 12,12a,12b,12c,12d,12e:Coating 14: Flow path 20: Module 30: Application unit 63: Pump (moving part) 100: Magnetic refrigeration device 111: Surface [Prior art documents] [Patent documents]

[0124] [Patent Document 1] Special Publication No. 2016-530479

Claims

1. A particle structure for use in a magnetic refrigeration device (100), comprising: Particles (11) having a magnetocaloric effect; a coating (12) covering a portion of the surface (111) of the particle; Equipped with the thermal conductivity of the coating is lower than the thermal conductivity of the particles; The coating has a uniform thickness along the surface, a grain structure (1).

2. The coating contains at least one resin selected from the group consisting of a thermosetting resin, a thermoplastic resin, and a photocurable resin. The particle structure of claim 1 .

3. The resin includes at least one of an epoxy resin, a melamine resin, a phenolic resin, a fluororesin, a polyethylene resin, and a polypropylene resin. The particle structure of claim 2.

4. The coating includes an inorganic adhesive. The particle structure of claim 1 .

5. The particles have a spherical shape. The particle structure according to any one of claims 1 to 4.

6. A particle structure according to any one of claims 1 to 4, A bed structure (10) in which channels (14) are formed between the particles for the passage of a fluid.

7. A plurality of bed structures according to claim 6 are provided, A module (20) in which the particles constituting the plurality of bed structures have different magnetocaloric effects.

8. A module according to claim 7; an application unit (30) that applies a magnetic field to the particles; a transfer section (63) for transferring a fluid that exchanges heat with the particles; A magnetic refrigeration device (100) comprising:

Images