Heat storage body, heat storage method, and method for manufacturing heat storage body

Abstract

To improve a heat storage technique.SOLUTION: A composition for heat storage 11 has a non-metal, meltable substance 12, and inorganic particles 13 at least some of which are not coupled to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to heat storage technology, and in particular to a heat storage composition, a heat storage body, a heat storage method, and a method for manufacturing a heat storage body. [Background technology]

[0002] In recent years, as environmental problems have become more serious, various measures to achieve energy conservation are required. For example, a heat storage technology has been developed that stores heat using electricity generated at a power generation facility during the night when electricity demand is low, and uses the stored heat during the day to reduce daytime electricity consumption (see, for example, Patent Document 1).

[0003] The use of phase change materials (PCMs) is being considered as heat storage materials, which can utilize not only the sensible heat of the material but also the latent heat that accompanies phase transitions such as solid-liquid transformation of the material. When using the latent heat that accompanies the solid-liquid transformation of the latent heat storage material, a structure is required that allows the shape of the heat storage material to be maintained even when the latent heat storage material transforms into a liquid phase, and a structure that prevents the liquid phase latent heat storage material from flowing out of the heat storage material.

[0004] As such heat storage materials, research is being conducted on heat storage materials in which a core of latent heat storage material is covered with a shell to maintain its shape, and heat storage materials in which latent heat storage material is impregnated and supported in a ceramic sintered body such as a porous body or capsule. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 07-190658 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have recognized that in order to further promote the use of heat storage bodies, it is necessary to develop a heat storage body that is cheaper and has a higher energy density.

[0007] The present disclosure has been made in view of these problems, and its purpose is to improve heat storage technology. [Means for solving the problem]

[0008] The thermal storage composition of the present disclosure comprises a non-metallic meltable material and inorganic particles at least some of which are not connected to one another.

[0009] The heat storage material of the present disclosure comprises the above-described heat storage composition and a coating formed on the outer peripheral surface of the heat storage composition.

[0010] The heat storage method of the present disclosure stores heat by utilizing the sensible heat of the non-metallic meltable substance, the latent heat associated with the solid-liquid transformation of the meltable substance, and the sensible heat of the inorganic particles.

[0011] The method for manufacturing a heat storage body of the present disclosure includes the steps of mixing a non-metallic meltable substance and inorganic particles, and molding the mixture.

[0012] The heat storage material of the present disclosure comprises the above-described heat storage composition and an outer shell that covers the heat storage composition.

[0013] The method for manufacturing a heat storage medium of the present disclosure includes the steps of forming an outer shell having an opening, and introducing the above-mentioned heat storage composition into the hollow portion inside the outer shell through the opening. [Effects of the Invention]

[0014] According to the present disclosure, heat storage technology can be improved. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram showing an example of a heat storage body according to a first embodiment of the present disclosure. [Figure 2]FIG. 10 is a diagram showing the change in the volume fraction of NaCl before and after heating a heat storage sample at 850°C. [Figure 3] FIG. 10 is a diagram showing the change in central temperature over time when a heat storage sample is repeatedly heated. [Figure 4] FIG. 10 is a diagram showing the change in height of a heat storage material sample over time in an electric furnace when the sample is heated. [Figure 5] FIG. 1 shows an SEM image and element map of a heat storage material sample. [Figure 6] FIG. 10 is a diagram showing the theoretical heat storage amount per volume of a heat storage material sample. [Figure 7] 7(a), (b), and (c) are diagrams showing examples of a heat storage body according to the second embodiment. [Figure 8] FIG. 10 is a diagram showing another example of a heat storage body according to the second embodiment. [Figure 9] 10 is a flowchart showing the steps of a method for manufacturing a heat storage body according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] (First embodiment) FIG. 1 shows an example of a thermal storage medium according to a first embodiment of the present disclosure. The area enclosed by a dashed line schematically illustrates the internal structure of the thermal storage medium 10. As shown on the left side of FIG. 1, the thermal storage medium 10 has a spherical shape formed from a thermal storage composition 11. The thermal storage composition 11 includes a nonmetallic meltable material 12 and a plurality of inorganic particles 13, at least some of which are not connected to one another. The meltable material 12 melts at a temperature when the thermal storage medium 10 is heated to store heat in the thermal storage medium 10, i.e., has a melting point lower than the heating temperature during heat storage, such as sodium chloride (NaCl). The inorganic particles 13 do not melt at the heating temperature during heat storage, but remain solid, and do not react much with the meltable material 12, such as alumina (Al2O3). The thermal storage medium 10 is formed by mixing a powder of the meltable material 12 and a powder of the inorganic particles 13, and molding the mixture into a spherical mold.

[0017] When the thermal storage body 10 is heated to a temperature above the melting point of the meltable substance 12, the meltable substance 12 melts, as shown on the right side of Figure 1. At this time, the meltable substance 12 in the liquid phase is present in the gaps between the unconnected inorganic particles 13. The liquid bridging forces generated between the inorganic particles 13 via the melted liquid phase meltable substance 12 form a network between the inorganic particles 13, forming a polymer gel-like structure. This allows the shape of the thermal storage body 10 to be maintained even when the meltable substance 12 melts and becomes liquid. Furthermore, the liquid meltable substance 12 is retained within the network of the inorganic particles 13, preventing the meltable substance 12 from leaking outside the thermal storage body 10. Because gas is also present in the gaps between the inorganic particles 13, when the meltable substance 12 melts, the liquid and gas phases become mixed. However, the inorganic particles 13 are thought to adsorb to the gas-liquid interface and function as surfactants (Pickering emulsions), stabilizing the liquid phase of the meltable substance 12.

[0018] According to the technology of this embodiment, a heat storage body 10 that can utilize the sensible heat of the meltable substance 12, the latent heat associated with the solid-liquid transformation of the meltable substance 12, and the sensible heat of the inorganic particles 13 can be realized without requiring any structure to maintain the shape, such as a shell, porous body, or capsule, which was required in heat storage bodies that use conventional latent heat storage materials, so that a heat storage body 10 with a large heat storage capacity can be provided at low cost.

[0019] The strength of the liquid bridge force generated between the meltable substance 12 and the inorganic particles 13 is determined by the wettability between the liquid phase meltable substance 12 and the inorganic particles 13. If no chemical reaction or the like is involved, the wettability between the meltable substance 12 and the inorganic particles 13 is determined by the surface tension of the liquid phase meltable substance 12 and the surface tension of the solid phase inorganic particles 13. Table 1 shows the physical properties of various inorganic salts, Table 2 shows the physical properties of various metals, and Table 3 shows the surface tension values ​​of various ceramic materials. [Table 1] [Table 2] [Table 3]

[0020] The surface tension of molten metal shown in Table 2 is 560 to 1300 mJ / m 2 ], but the wettability between molten metal and ceramic materials is generally low. In contrast, the surface tension of the molten inorganic salts shown in Table 1 is 50 to 250 [mJ / m 2 ], which is lower than that of molten metal, so that the wettability with the ceramic material is good. Therefore, by using an inorganic salt as the meltable substance 12, a sufficient liquid bridging force can be obtained with the inorganic particles 13.

[0021] The meltable substance 12 has a surface tension of 50 to 250 [mJ / m 2 The lower limit of the surface tension of the meltable substance 12 may be 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 [mJ / m 2 The upper limit of the surface tension of the meltable substance 12 may be 100, 150, 200, 250, 300, 350, 400, 450, 500, or 550 [mJ / m 2 ] may also be used.

[0022] The meltable material 12 may include a chloride, a fluoride, a carbonate, a nitrate, or a combination of two or more thereof. More specifically, the meltable material 12 may include ZnCl2, LiCl, MgCl2, RbCl, KCl, CaCl2, NaCl, SrCl2, BaCl2, LIF, KF, NaF, Li2CO3, Na2CO3, K2CO3, LiNO3, NaNO3, KNO3, CA(NO3)2, or a combination of two or more thereof.

[0023] The inorganic particles 13 have a surface tension of 1000 to 2000 [mJ / m 2 The lower limit of the surface tension of the inorganic particles 13 may be 500, 600, 700, 800, 900, 1000, 1100, 1200, or 1300 [mJ / m2 The upper limit of the surface tension of the inorganic particles 13 may be 1400, 1500, 1600, 1700, 1800, 1900, or 2000 [mJ / m 2 ] may also be used.

[0024] The inorganic particles 13 may include Al2O3, SiO2, SiC, Si3N4, mullite, aluminum titanate, TiO2, or a mixture of two or more thereof.

[0025] The average particle size of the inorganic particles 13 may be 1 μm or less. The upper limit of the average particle size of the inorganic particles 13 may be 1.5 μm, 1.0 μm, 0.9 μm, 0.8 μm, 0.7 μm, 0.6 μm, 0.5 μm, 0.4 μm, 0.3 μm, 0.2 μm, or 0.1 μm. By using inorganic particles with a larger specific surface area than conventional ceramic porous bodies, the wetted area can be increased, and therefore more meltable material 12 can be retained.

[0026] The volume ratio of the inorganic particles 13 in the heat storage composition constituting the heat storage body 10 may be less than 40% of the total volume. The upper limit of the volume ratio of the inorganic particles 13 may be 60%, 50%, 40%, 35%, 30%, 25%, 20%, or 15% of the total volume. The lower limit of the volume ratio of the inorganic particles 13 may be 5%, 10%, 15%, 20%, 25%, or 30% of the total volume. This allows the heat storage amount per unit volume of the heat storage body 10 to be improved. Furthermore, the shape of the meltable substance 12 of the heat storage body 10 can be maintained even when it melts.

[0027] The heat storage body 10 may have a coating formed on the outer peripheral surface of the heat storage composition 11 containing a meltable substance 12 and inorganic particles 13. This coating may contain inorganic particles 13. The coating may be formed, for example, by molding the heat storage composition 11 and then heating the heat storage composition 11 to a temperature equal to or higher than the melting point of the meltable substance 12, thereby removing the meltable substance 12 present on the outer peripheral surface of the heat storage composition 11 and exposing the inorganic particles 13. The coating may be formed of a substance different from the inorganic particles 13. In this case, the coating may be molded integrally with the heat storage composition 11 when molding the heat storage composition 11, or may be formed on the outer peripheral surface of the heat storage composition 11 after the heat storage composition 11 has been molded.

[0028] The coating may have many minute pores, which allows the gas around the heat storage body 10 to pass through the coating and come into contact with the meltable substance 12 and the inorganic particles 13, thereby enabling efficient heat exchange.

[0029] [Example 1] Al2O3 powder (AES-12, Sumitomo Chemical) and NaCl powder (melting point: 801°C) were mixed at a volume fraction of 60–95% NaCl, and then molded into a 12 mm diameter silicone resin mold with a 1 wt% binder solution (15 wt% of the powder). The mixture was dried at room temperature for 1 day and then at 90°C for 2 hours. The resulting NaCl / Al2O3 composite spheres were heated in an electric furnace at a rate of 5°C per minute to 850°C and then held at 850°C for 10 minutes. The changes in weight and diameter before and after heating were measured. Images of the 100 / 0 and 80 / 20% NaCl / Al2O3 samples were photographed during heating in the electric furnace, and the change in sample height (H) over time (ΔH) was calculated by image analysis.

[0030] Figure 2 shows the change in the volume fraction of NaCl before and after heating a heat storage sample to 850°C. The dashed line shows the plot when the volume fraction did not change before and after heating. In samples with a NaCl volume fraction of 80% or less, there was almost no change in the volume fraction before and after heating. This confirmed that even without a shell structure, leakage of NaCl to the outside could be suppressed when heated above the melting point of NaCl.

[0031] Figure 3 shows the change in central temperature over time when a heat storage sample was repeatedly heated. A sample with NaCl / Al2O3 = 80 / 20 volume percent was repeatedly heated and cooled between 700°C and 850°C. A temperature plateau corresponding to the endothermic heat generated during melting was confirmed at 801°C, the melting point of NaCl. This confirms that even in a heat storage sample with a structure in which NaCl and Al2O3 powders are mixed, the NaCl inside repeatedly melts and solidifies.

[0032] Figures 4(a) and (b) show the change in sample height over time in an electric furnace when a thermal storage sample was heated. Figure 4(a) shows an image of the sample's appearance in the electric furnace. The sample height (H) at 640°C was used as the reference height. Figure 4(b) shows the change in sample height over time (ΔH) in the electric furnace when samples with NaCl / Al2O3 = 100 / 0 and 80 / 20 vol% were heated at 850°C. The NaCl-only sample rapidly decreased in ΔH when the temperature exceeded the melting point of NaCl, 801°C, because the NaCl melted and became liquid, losing its shape. In contrast, the ΔH of the NaCl / Al2O3 = 80 / 20 vol% sample remained almost unchanged even at 850°C. This confirmed that this sample maintained its shape even when the NaCl melted.

[0033] Figure 5 shows an SEM image and elemental map of a heat storage sample. Figure 5(a) is an SEM image of a cross section of the heat storage sample, and Figure 5(b) is an enlarged view of a portion of Figure 5(a). Figures 5(c), 5(d), and 5(e) show X-ray elemental maps of the region shown in Figure 5(b). Figure 5(c) shows the distribution of Al, Figure 5(d) shows Na, and Figure 5(e) shows Cl. NaCl was found to be present in the voids of the Al2O3 network structure. When the heat storage composition is molded, the meltable material and inorganic particles are dispersed. However, by heating the molded heat storage composition above the melting point of the meltable material, liquid bridging forces are generated between the inorganic particles via the meltable material in the molten liquid phase, causing the inorganic particles to rearrange and form a skeleton with a network structure. As a result, the shape of the heat storage material is maintained by the inorganic particle skeleton, even when the meltable material melts and becomes liquid.

[0034] Figure 6 shows the theoretical heat storage capacity per volume of the heat storage sample. When the theoretical heat storage capacity per volume of the NaCl / Al2O3 heat storage material was calculated, it was found that it reached its maximum when the volume fraction of NaCl was 70 to 80% by volume.

[0035] (Second embodiment) As a first embodiment of the present disclosure, a heat storage body that does not require a configuration for maintaining its shape has been described. When multiple such heat storage bodies are introduced into a heat storage tank or the like and used, the shape of each heat storage body can be maintained even when the meltable material is melted by heating. However, there is a possibility that the heat storage bodies may fuse together via the meltable material, which may be undesirable depending on the application. Furthermore, depending on the application, the change in appearance of the heat storage body when the meltable material melts may be undesirable.

[0036] In order to solve this problem, the heat storage body according to the second embodiment has an outer shell that covers the heat storage composition according to the first embodiment, which makes it possible to prevent the heat storage bodies from fusing together and the appearance of the heat storage body from changing even if the meltable substance in the heat storage body melts.

[0037] Figures 7(a), (b), and (c) show examples of a heat storage body according to the second embodiment. Figures 7(a) and 7(b) show examples of the external appearance of a heat storage body 20. In the example of Figure 7(a), an opening 22 for introducing the heat storage composition 11 into the interior is provided in the outer shell 21. In the example of Figure 7(b), after the heat storage composition 11 is introduced into the hollow portion through the opening 22, the opening 22 is sealed with a sealing material 23 such as castable. Figure 7(c) shows the state in which the outer shell 21 of the heat storage body 20 has been cut. The hollow portion inside the spherical outer shell 21 is filled with the heat storage composition 11.

[0038] The outer shell 21 may be formed from any material having a melting point higher than that of the meltable substance 12 contained in the heat storage composition 11. The outer shell 21 may be formed from alumina, silica, silicon nitride, silicon carbide, a metal, an alloy, or a composite material containing a combination of two or more of these. In order to improve heat transfer by thermal radiation, the outer shell 21 may be colored black with a dye or pigment.

[0039] The size of the outer shell 21 may be, for example, 1 to 100 mm, preferably 10 to 50 mm. The size of the outer shell 21 may be expressed as the height of the outer shell 21. By appropriately reducing the size of the outer shell 21, it is possible to increase the filling rate when filling a heat storage tank or the like with the heat storage medium 20, thereby increasing the amount of heat storage. Furthermore, by appropriately increasing the size of the outer shell 21, it is possible to increase the gaps between the heat storage medium 20 inside the heat storage tank, thereby making it easier for fluid to flow inside the heat storage tank and reducing pressure loss.

[0040] Fig. 8 shows another example of a heat storage medium according to the second embodiment. The heat storage medium 20 shown in this figure has a tetrapod (registered trademark) shape with four protrusions 24 formed toward the vertices of a regular tetrahedron. This allows the heat transfer area to be larger than that of a sphere or an ellipsoid, thereby improving the heat storage efficiency and heat exchange efficiency. It is also less likely to be crushed than a sphere or an ellipsoid.

[0041] According to the heat storage body 20 shown in this figure, when a heat storage tank is filled with multiple heat storage bodies 20, it is possible to create appropriate gaps between adjacent heat storage bodies 20 and reduce unevenness of the gaps. This allows fluids such as air to easily flow through the gaps between the heat storage bodies 20, thereby reducing pressure loss in the heat storage tank. Furthermore, when multiple heat storage bodies 20 are filled in a heat storage tank with a random orientation, it is possible to make the fluid that flows into the heat storage tank more likely to flow in a turbulent state rather than a laminar state. This allows the high-temperature fluid that flows into the heat storage tank to flow throughout the entire heat storage tank, thereby allowing heat to be efficiently stored in the multiple heat storage bodies 20 filled in the heat storage tank.

[0042] The heat storage body 20 may have protrusions 24 formed at the vertices of a regular hexahedron, regular octahedron, regular dodecahedron, or regular icosahedron, or may have the shape of a star-shaped regular polyhedron. The protrusions 24 may be provided so as to be point-symmetrical about the vicinity of the center of gravity of the outer shell 21, or so as to be line-symmetrical about a line passing through the vicinity of the center of gravity of the outer shell 21. Providing the protrusions 24 with some symmetry in this way can reduce unevenness in the voids when multiple heat storage bodies 20 are filled in a heat storage tank, thereby improving heat storage efficiency and reducing pressure loss. The heat storage body 20 may have protrusions 24 formed in any direction.

[0043] The height of the protrusions 24 may be, for example, 3 to 50 mm, preferably 5 to 25 mm. The number of the protrusions 24 may be, for example, 1 to 100, preferably 2 to 20. By appropriately increasing the height or number of the protrusions 24, the gaps between the heat storage bodies 20 in the heat storage tank can be increased, thereby facilitating the flow of fluid inside the heat storage tank and reducing pressure loss. Furthermore, by appropriately decreasing the height or number of the protrusions 24, the filling rate of the heat storage body 20 in the heat storage tank can be increased, thereby increasing the amount of heat storage. The shape of the protrusions 24 may be a cone, a column, a hemisphere, a part of a body of revolution, or the like.

[0044] FIG. 9 is a flowchart showing the steps of a method for manufacturing a thermal storage medium according to the second embodiment. First, an outer shell 21 having an opening 22 is formed (S10). The outer shell 21 may be formed by slip casting or the like. A dispersion in which raw materials for forming the outer shell 21 are dispersed in a dispersion medium is poured into a cavity of a plaster mold formed from plaster. After the dispersion medium is left to stand for a while, the dispersion medium is absorbed by the plaster mold, and the raw materials are deposited on the molding surface of the cavity with a substantially uniform thickness. An impermeable portion that does not allow the dispersion medium to pass through may be provided on the molding surface of the plaster mold at the portion of the opening 22. When water is used as the dispersion medium, the impermeable portion may be provided by applying, for example, a hydrophobic lubricant or coating agent to the molding surface. Since the dispersion medium is not absorbed by the impermeable portion of the plaster mold, the raw materials are not deposited on the impermeable portion. The formed outer shell 21 is released from the plaster mold and dried or sintered to form the outer shell 21. The plaster mold may have a shape without undercuts or reverse tapers. This allows the formed outer shell 21 to be easily released from the mold, thereby reducing manufacturing costs.

[0045] Next, the heat storage composition 11 is introduced into the hollow space inside the shell 21 through the opening 22 (S12). The heat storage composition 11 may be a powder having various particle sizes. Any technique for densely packing the powder may be used.

[0046] Next, the heat storage composition 11 introduced into the hollow portion is heated to a temperature equal to or higher than the melting point of the meltable substance 12 (S14). When the heat storage composition 11 is cooled after heating, the melted meltable substance 12 solidifies, forming a solid mixture in which the meltable substance 12 and inorganic particles 13 are integrated. Even if the powder of the heat storage composition 11 is filled to the full extent of the hollow portion, the volume of the solid mixture will be smaller than the volume of the hollow portion by the volume of the gaps between the powder particles. The space created by the solidification of the meltable substance 12 may be filled with more powder of the heat storage composition 11.

[0047] If necessary, the opening 22 may be sealed after the heat storage composition 11 is introduced into the hollow portion (S16). The opening 22 may be sealed before the heat storage composition 11 is heated, or may be sealed after the heat storage composition 11 is heated.

[0048] [Example 2] A spherical outer shell 21 having an opening 22 was formed from Si3N4. A heat storage composition 11, which was a mixture of Al2O3 powder and NaCl powder in a volume fraction of Al2O3:NaCl = 20:80, was introduced into the hollow inside the outer shell 21 through the opening 22. The composition was placed in an electric furnace with the opening 22 facing up and heated at 850°C for 10 minutes to produce the heat storage body 20 shown in Figure 7(a). The opening 22 of the heat storage body 20 produced in the same manner was sealed with castable to produce the heat storage body 20 shown in Figure 7(b).

[0049] In order to confirm the performance of these heat storage bodies 20, they were placed in an electric furnace with the opening 22 facing downwards and heated at 850°C for 2 hours, and the changes in weight and appearance before and after heating were observed. No leakage of the heat storage composition 11 was observed externally in any of the heat storage bodies 20. Furthermore, no weight loss due to heating was observed in any of the heat storage bodies 20. Therefore, even if the opening 22 is not sealed, the heat storage body 20 can be used without losing the heat storage composition 11 inside, and the manufacturing cost of the heat storage body 20 can be reduced. Even when the opening 22 is sealed to improve the appearance, etc., it can be simply sealed, and the manufacturing cost of the heat storage body 20 can be reduced.

[0050] The heat storage body 10 of the first embodiment may also have the protrusions 24 in the same manner.

[0051] The outline of the aspects of the present disclosure is as follows.

[0052] The heat storage composition of the present disclosure includes a non-metallic meltable substance and inorganic particles at least some of which are not connected to each other. According to this aspect, it is possible to provide a heat storage medium that is inexpensive and has a large heat storage capacity.

[0053] In the heat storage composition of the present disclosure, the volume ratio of the inorganic particles does not need to exceed 40% of the total volume. According to this embodiment, it is possible to provide an inexpensive heat storage medium with a large heat storage capacity.

[0054] In the heat storage composition of the present disclosure, the meltable substance has a melting point lower than the temperature at which the heat storage composition is heated to store heat in the heat storage composition. According to this embodiment, heat can be stored using not only the sensible heat of the meltable substance but also the latent heat, so that an inexpensive heat storage medium with a large heat storage capacity can be provided.

[0055] In the heat storage composition of the present disclosure, the meltable substance has a surface tension of 50 to 250 mJ / m 2 According to this aspect, it is possible to prevent the meltable substance from leaking out of the heat storage body when it melts.

[0056] In the heat storage composition of the present disclosure, the meltable substance may include a chloride, a fluoride, a carbonate, a nitrate, or a combination of two or more thereof. According to this embodiment, it is possible to provide an inexpensive heat storage medium with a large heat storage capacity.

[0057] In the heat storage composition of the present disclosure, the meltable substance may include ZnCl2, LiCl, MgCl2, RbCl, KCl, CaCl2, NaCl, SrCl2, BaCl2, LIF, KF, NaF, Li2CO3, Na2CO3, K2CO3, LiNO3, NaNO3, KNO3, CA(NO3)2, or a combination of two or more thereof. According to this embodiment, it is possible to provide an inexpensive heat storage medium with a large heat storage capacity.

[0058] In the heat storage composition of the present disclosure, the inorganic particles do not melt but remain in a solid state at the temperature at which the heat storage composition is heated to store heat in the heat storage composition. According to this aspect, even when the meltable substance melts, the shape of the heat storage composition can be maintained by the inorganic particles, so that heat can be stored using not only the sensible heat of the meltable substance but also the latent heat, and it is possible to provide a heat storage body that is inexpensive and has a large heat storage capacity.

[0059] In the heat storage composition of the present disclosure, the inorganic particles may contain Al2O3, SiO2, SiC, Si3N4, mullite, aluminum titanate, TiO2, or a mixture of two or more thereof. According to this embodiment, it is possible to provide an inexpensive heat storage medium with a large heat storage capacity.

[0060] In the heat storage composition of the present disclosure, the inorganic particles may have an average particle size of 1 μm or less. According to this embodiment, leakage of the meltable substance to the outside of the heat storage body when melted can be suppressed.

[0061] The heat storage material of the present disclosure includes any one of the heat storage compositions described above and a coating formed on the outer peripheral surface of the heat storage composition. According to this aspect, it is possible to provide a heat storage material that is inexpensive and has a large heat storage capacity.

[0062] In the heat storage material of the present disclosure, the coating may contain inorganic particles. According to this aspect, it is possible to provide a heat storage material that is inexpensive and has a large heat storage capacity.

[0063] In the heat storage material of the present disclosure, a meltable substance may be present in the gaps between the inorganic particles. According to this aspect, it is possible to prevent the meltable substance from leaking out of the heat storage material when it melts.

[0064] In the heat storage material of the present disclosure, when the meltable substance melts, the inorganic particles may be liquid-bridged to maintain the shape of the heat storage material. According to this aspect, when the meltable substance melts, leakage of the meltable substance to the outside of the heat storage material can be suppressed.

[0065] The heat storage method of the present disclosure stores heat by utilizing the sensible heat of the non-metallic meltable substance, the latent heat associated with the solid-liquid transformation of the meltable substance, and the sensible heat of the inorganic particles. According to this aspect, it is possible to provide a heat storage medium that is inexpensive and has a large heat storage capacity.

[0066] The method for manufacturing a heat storage medium of the present disclosure includes the steps of mixing a non-metallic meltable substance and inorganic particles, and molding the mixture. According to this aspect, it is possible to provide a heat storage medium that is inexpensive and has a large heat storage capacity.

[0067] The method for producing a heat storage medium of the present disclosure further includes a step of heating the shaped mixture to a temperature equal to or higher than the melting point of the meltable substance, thereby generating a liquid bridging force between the inorganic particles via the meltable substance in a molten liquid phase, and forming a skeleton of the inorganic particles. According to this aspect, even when the meltable substance melts, the shape of the heat storage medium can be maintained by the skeleton of the inorganic particles, so that heat can be stored using not only the sensible heat of the meltable substance but also the latent heat, and it is possible to provide a heat storage medium that is inexpensive and has a large heat storage capacity.

[0068] The heat storage medium of the present disclosure includes any one of the heat storage compositions described above and an outer shell covering the heat storage composition. According to this aspect, even if the meltable substance in the heat storage medium melts, it is possible to prevent the heat storage medium from fusing together and the appearance of the heat storage medium from changing.

[0069] The method for manufacturing a heat storage medium of the present disclosure comprises the steps of forming an outer shell having an opening, and introducing any of the above-described heat storage compositions into the hollow space inside the outer shell through the opening. According to this aspect, the heat storage body of the present disclosure can be manufactured inexpensively.

[0070] The method for producing a heat storage medium according to the present disclosure may further include a step of heating the heat storage composition introduced into the hollow portion to a temperature equal to or higher than the melting point of the meltable substance. According to this aspect, the heat storage medium according to the present disclosure can be produced inexpensively.

[0071] The method for producing a heat storage medium according to the present disclosure may further include a step of sealing the opening after introducing the heat storage composition into the hollow portion. According to this aspect, the heat storage medium according to the present disclosure can be produced inexpensively. [Explanation of symbols]

[0072] 10 heat storage body, 11 heat storage composition, 12 meltable substance, 13 inorganic particles, 20 heat storage body, 21 outer shell, 22 opening, 23 sealing material 24 protrusion.

Claims

1. a heat storage composition comprising a meltable substance having a melting point lower than the temperature at which the heat storage body is heated to store heat in the heat storage body, and inorganic particles having an average particle size of 1 μm or less; an outer shell covering the heat storage composition; A heat storage body comprising:

2. A heat storage method for storing heat by utilizing the sensible heat of the meltable substance in the heat storage material according to claim 1, the latent heat associated with the solid-liquid transformation of the meltable substance, and the sensible heat of inorganic particles.

3. A method for manufacturing a thermal storage body, comprising the steps of: forming an outer shell having an opening; a step of introducing a heat storage composition containing a meltable substance having a melting point lower than the temperature at which the heat storage body is heated to store heat in the heat storage body, and inorganic particles having an average particle size of 1 μm or less, into the hollow portion inside the outer shell through the opening; A method for providing the above.

4. The method further includes a step of heating the heat storage composition introduced into the hollow portion to a melting point of the meltable substance or higher. The method of claim 3.

5. The method further includes a step of sealing the opening after the heat storage composition is introduced into the hollow portion. The method according to claim 3 or 4.

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