Thermal storage particles, thermal storage member, and thermal storage device

Abstract

To provide thermal storage particles which inhibit particle fragmentation due to repeated thermal storage and release reactions to maintain the reactivity over an extended period, exhibit high thermal storage density, and are easily applicable to thermal storage members and thermal storage devices of various structures.SOLUTION: A thermal storage particle has a core section 10 and a shell section 20 that covers the core section 10, wherein the shell section 20 contains a thermal storage material, and the core section 10 is composed of a hollow region or a shrinkable material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to heat storage particles, a heat storage member, and a heat storage device.

Background Art

[0002] As a technology for effectively using thermal energy such as exhaust heat toward the realization of a deoxygenated society, heat storage materials have attracted attention. Among them, chemical heat storage materials can realize a heat storage reaction and a heat dissipation reaction by utilizing the heat of chemical reaction generated when contacting a reaction medium, and if the chemical heat storage material and the reaction medium are physically separated, the heat storage state can be maintained over a long period. In addition, since chemical heat storage materials have a higher heat storage density than other heat storage materials such as latent heat storage materials, they are suitable for use in heat storage devices. Chemical heat storage materials are often used in a particulate form depending on the type of heat storage device. However, when the particulate chemical heat storage material repeatedly performs a heat storage reaction and a heat dissipation reaction, expansion and contraction of several tens of percent of the volume occur. At this time, it is known that the expanded particles collapse due to friction and become pulverized, and the reactivity of the chemical heat storage material gradually decreases.

[0003] Therefore, in order to solve the above problems, Patent Document 1 proposes a chemical heat storage material molded body having a skeleton structure portion made of porous ceramics having a large number of pores, and a chemical heat storage material supported on the outer surface of the skeleton structure portion, or the outer surface and the inside of the pores of the skeleton structure portion. Further, Patent Document 2 proposes a chemical heat storage material composite obtained by mixing a clay mineral and a structure strength improving material with a powder chemical heat storage material and firing the mixture.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the chemical heat storage material molded body of Patent Document 1 has the chemical heat storage material supported on the skeleton structure portion made of ceramics, the heat storage density decreases. Furthermore, since this chemical heat storage material molded body has a structure in which the chemical heat storage body is supported on the skeleton structure portion, restrictions are imposed on the shape and size, and it is difficult to use it in heat storage devices having various structures. Similarly, since the chemical heat storage material composite of Patent Document 2 is formed by dispersing and retaining the chemical heat storage material in the skeleton of the clay mineral and the structure strength improving material and organizing / structuring it, the heat storage density decreases. Also, since this chemical heat storage material composite is restricted in shape and size, it is difficult to use it in heat storage devices having various structures.

[0006] The present invention has been made to solve the above problems, and aims to provide heat storage particles that can suppress atomization due to repeated heat storage reactions and heat release reactions and maintain reactivity over a long period, have a high heat storage density, and are easy to use in heat storage members and heat storage devices having various structures. Further, the present invention aims to provide a heat storage member and a heat storage device including the heat storage particles having the above characteristics.

Means for Solving the Problems

[0007] As a result of intensive research on the heat storage particles, the present inventors have found that the above problems can be solved by adopting a structure having a specific core portion and shell portion, and have completed the present invention. That is, the present invention is exemplified as follows.

[0008] [1] Heat storage particles having a core portion and a shell portion covering the core portion, wherein the shell portion contains a heat storage material, the core portion is a heat storage particle composed of a hollow region or a shrinkable material.

[0009] [2] The heat storage particles according to [1], wherein the heat storage material is a chemical heat storage material.

[0010] [3] The heat storage particles according to [2], wherein the chemical heat storage material is a hydroxide of an alkaline earth metal.

[0011] [4] The heat storage particles according to [3], wherein the hydroxide of the alkaline earth metal is calcium hydroxide, magnesium hydroxide, or a mixture thereof.

[0012] [5] The heat storage density of the shell part is 0.2 GJ / m 3 or more, and the heat storage particles according to any one of [1] to [4].

[0013] [6] The heat storage particles according to any one of [1] to [5], wherein the porosity of the core part is 10% or more.

[0014] [7] The heat storage particles according to any one of [1] to [6], wherein the core part is made of a shrinkable material, and its Young's modulus is 650 GPa or less.

[0015] [8] The heat storage particles according to any one of [1] to [7], wherein the shrinkable material includes ceramics, metals, organic compounds, or a mixture thereof.

[0016] [9] The heat storage particles according to any one of [1] to [8], and a housing part in which the heat storage particles are housed and a heat storage member provided with the same.

[0017]

[10] The heat storage member according to [9], wherein the housing part is made of metal or ceramics.

[0018]

[11] The heat storage member according to [9] or

[10] , wherein the housing part is a honeycomb structure made of ceramics having an outer peripheral wall and a partition wall disposed inside the outer peripheral wall and partitioning a plurality of cells extending from a first end face to a second end face, and at least a part of the cells houses the heat storage material.

[0019]

[12] The heat storage member according to

[11] , wherein the ceramics constituting the honeycomb structure contains SiC or alumina.

[0020]

[13] The heat storage member according to any one of [9] to

[12] , and means for heating the heat storage particles in the heat storage member A heat storage device comprising.

Effect of the Invention

[0021] According to the present invention, it is possible to suppress atomization due to repeated heat storage reactions and heat release reactions, maintain reactivity over a long period of time, have a high heat storage density, and provide heat storage particles that are easy to use in heat storage members and heat storage devices having various structures. Further, according to the present invention, it is possible to provide a heat storage member and a heat storage device including heat storage particles having the above-described characteristics.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Mode for Carrying Out the Invention

[0023] The present invention relates to heat storage particles having a core part and a shell part covering the core part, wherein the shell part contains a heat storage material, and the core part is composed of a hollow region or a contractible material. Heat storage particles having such a configuration are less likely to cause a volume change of the heat storage particles because when the shell part containing the heat storage material expands during an exothermic reaction, the core part absorbs the expansion of the shell part. As a result, even when the heat storage reaction and the exothermic reaction are repeated, friction between the heat storage particles is less likely to occur, so that atomization (disintegration) of the heat storage particles can be suppressed, and reactivity can be maintained over a long period. Further, since these heat storage particles are not supported or dispersed and held in various skeletal structure parts and are in a particulate form, they have a high heat storage density and are easy to use because there is no need to adjust the shape according to the type of heat storage member or heat storage device to be used.

[0024] The present invention also relates to a heat storage member including the above heat storage particles and a housing part in which the heat storage particles are housed. A heat storage member having such a configuration is such that each heat storage particle housed in the housing part is restricted by adjacent heat storage particles and the housing part, so that it is difficult for the heat storage particles to expand outward during an exothermic reaction. Further, since the above heat storage particles absorb the expansion of the shell part when the shell part expands during an exothermic reaction, a volume change of the heat storage particles is less likely to occur. As a result, even when the heat storage reaction and the exothermic reaction are repeated, friction between the heat storage particles is less likely to occur, so that atomization (disintegration) of the heat storage particles can be suppressed, and reactivity can be maintained over a long period.

[0025] Furthermore, the present invention relates to a heat storage device including the above heat storage member and means for heating the heat storage particles in the above heat storage member. A heat storage device having such a configuration includes the above heat storage member, so that the reactivity is less likely to decrease even when the heat storage reaction and the exothermic reaction are repeated, and the heat storage reaction and the exothermic reaction can be maintained over a long period.

[0026] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and modifications, improvements, etc. may be appropriately added to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention, and such modified embodiments also fall within the scope of the present invention.

[0027] <Heat storage particles> FIG. 1 is a schematic cross-sectional view of heat storage particles according to an embodiment of the present invention. As shown in FIG. 1, the heat storage particle 1 according to the embodiment of the present invention has a core portion 10 and a shell portion 20 that covers the core portion 10. The core portion 10 is made of a hollow region or a shrinkable material. The shell portion 20 contains a heat storage material.

[0028] The heat storage particles 1 can be used by being housed in a housing portion such as a container. Here, FIG. 2 shows a schematic cross-sectional view for explaining the heat storage state and heat dissipation state of the heat storage particles 1 housed in the housing portion. In the heat storage state, the heat storage particles 1 shrink due to the heat storage reaction of the heat storage material (for example, dehydration reaction when water is used as the reaction medium). Specifically, as shown in the left diagram of FIG. 2, the inner peripheral side of the shell portion 20 containing the heat storage material mainly shrinks. In the left diagram of FIG. 2, the dotted line represents the position of the inner peripheral side of the shell portion 20 in the heat dissipation state, and the arrow represents the shrinking direction of the shell portion 20. In the heat dissipation state, the heat storage particles 1 expand due to the heat dissipation reaction of the heat storage material (for example, hydration reaction when water is used as the reaction medium). Specifically, as shown in the right diagram of FIG. 2, the inner peripheral side of the shell portion 20 containing the heat storage material mainly expands. In the right diagram of FIG. 2, the dotted line represents the position of the inner peripheral side of the shell portion 20 in the heat storage state, and the arrow represents the expansion direction of the shell portion 20. When the heat storage reaction and heat dissipation reaction are repeated, the heat storage particles 1 are restricted by adjacent heat storage particles 1 and the housing portion 100, so it is difficult for the outer peripheral side of the shell portion 20 to expand and contract. Therefore, even when the heat storage reaction and heat dissipation reaction are repeated, friction between the heat storage particles 1 is unlikely to occur, and atomization (collapse) of the heat storage particles 1 can be suppressed.

[0029] The heat storage material contained in the shell portion 20 is not particularly limited, but is preferably a chemical heat storage material. As described above, when the chemical heat storage material repeatedly performs the heat storage reaction and heat dissipation reaction, expansion and contraction of several tens of percent of the volume occur, so the above effects are easily obtained.

[0030] Examples of the chemical heat storage material include, in the state after the heat release reaction, calcium hydroxide (Ca(OH) 2 ), magnesium hydroxide (Mg(OH) 2 ), etc., hydroxides of alkaline earth metals; sodium hydroxide (NaOH), lithium hydroxide (LiOH), etc., hydroxides of alkali metals; MgCl 2 ·2NH 3 , CaCl 2 ·4NH 3 , etc., ammonia complexes, MgCO 3 , CaCO 3 , etc., carbonates, and the like. For example, hydroxides of alkali metals and hydroxides of alkaline earth metals are used when the reaction medium used in the heat release reaction is water. Ammonia complexes are used when the reaction medium used in the heat release reaction is ammonia. Carbonates are used when the reaction medium used in the heat release reaction is carbon dioxide. If the types of the reaction media are the same, two or more of the above-described chemical heat storage materials can be used in combination. Among the above-described chemical heat storage materials, hydroxides of alkaline earth metals and hydroxides of alkali metals that can use water as the reaction medium are preferable, hydroxides of alkaline earth metals are more preferable, and calcium hydroxide, magnesium hydroxide, or a mixture thereof is even more preferable.

[0031] The shell portion 20 preferably has a heat storage density of 0.2 GJ / m 3 or more. With such a heat storage density, a heat storage member and a heat storage device having high heat storage performance can be obtained. Since the heat storage performance can be enhanced as the heat storage density is larger, the upper limit is not particularly limited, but is, for example, 7 GJ / m 3 . Here, the heat storage density in this specification is the heat storage amount (GJ) per unit volume (1 m 3 ). The heat storage density can be calculated by measuring the heat storage amount of the heat storage particles 1 using a differential scanning calorimeter and dividing it by the volume of the shell portion 20.

[0032] The heat storage material contained in the shell part 20 is not particularly limited, but is preferably in the form of fine particles. If the heat storage material is in the form of fine particles, the surface area of the heat storage material increases, so that the reaction efficiency can be enhanced. The median diameter of the particulate heat storage material is not particularly limited, but is preferably 5 to 100 μm. If the median diameter exceeds 100 μm, the surface area may decrease, and thus the desired reaction efficiency may not be obtained. Further, if the median diameter is less than 5 μm, the number of particulate heat storage materials constituting the shell part 20 increases. As a result, it becomes difficult to appropriately control the expansion and contraction of the shell part 20, and cracks may occur in the shell part 20. Here, in this specification, the median diameter means the particle diameter (D50) at the integrated value of 50% in the particle size distribution determined by the laser diffraction / scattering method.

[0033] The shell part 20 can further contain components other than the heat storage material as long as the effects of the present invention are not inhibited. Examples of the components other than the heat storage material include, for example, a binder and the like. The binder is not particularly limited, and known ones can be used.

[0034] The volume of the shell part 20 is not particularly limited, but is preferably 1.7×10 -4 ~4.2 mm 3 If it is in such a range, the heat storage density can be increased.

[0035] As described above, the core part 10 is composed of a hollow region or a material that can contract. The core part 10 preferably has a porosity of 10% or more. If the core part 10 has a porosity in such a range, it becomes easier for the core part 10 to absorb the expansion of the shell part 20. Here, the porosity of the core part 10 means the porosity measured using a gas pycnometer (Accupic II 1345 series manufactured by Shimadzu Corporation). When the core part 10 is a hollow region, the porosity can be said to be 100%.

[0036] When the core part 10 is made of a material that can contract, its Young's modulus is preferably 650 GPa or less. With a core part 10 made of a material having such a Young's modulus, it becomes easier for the core part 10 to absorb the expansion of the shell part 20. Here, the Young's modulus of the core part 10 is measured by evaluating the elastic modulus using a scanning probe microscope.

[0037] The material that can contract is not particularly limited, and for example, it can include ceramics, metals, organic compounds, or mixtures thereof. Examples of ceramics include clay minerals, SiC, alumina, zirconia, etc. Examples of metals include gold, platinum, iridium, rhodium, palladium, titanium alloys, stainless steel, nickel alloys, chromium, zirconium, niobium-aluminum alloys, etc. Examples of organic compounds include polyimide, etc. The exemplified ceramics, metals, and organic compounds can be used alone or in combination of two or more.

[0038] When the core part 10 is composed of a hollow region, it is preferable that the shell part 20 has airtightness. With such a configuration, the gas (air) in the hollow region that expands due to heating during the heat storage reaction can support the shell part 20, so that the contraction of the heat storage particles 1 can be suppressed. Here, in this specification, "the shell part 20 has airtightness" means that gas (air) does not pass through the inside of the shell part 20. The shell part 20 having airtightness can be realized, for example, by filling the spaces between the fine particle-shaped heat storage materials with other components such as a binder.

[0039] The volume of the core part 10 is not particularly limited, but it is preferably 3.3×10 -5 ~3.1 mm 3 If it is within such a range, it becomes easier for the core part 10 to absorb the expansion of the shell part 20. On the other hand, when the volume of the core part 10 is 3.3×10 -5 mm 3If it is less than that, it becomes difficult for the core part 10 to absorb the expansion of the shell part 20. Also, when the volume of the core part 10 exceeds 3.1 mm 3 it becomes difficult to use in heat storage members and heat storage devices having various structures because the heat storage particles 1 become large.

[0040] The volume of the heat storage particle 1 (total volume of the core part 10 and the shell part 20) composed of the core part 10 and the shell part 20 is not particularly limited, but is preferably 2.1×10 -4 ~7.3 mm 3 If it is within such a range, it becomes easier for the core part 10 to absorb the expansion of the shell part 20 while increasing the heat storage density.

[0041] The manufacturing method of the heat storage particle 1 having the above structure is not particularly limited and can be carried out according to known methods. For example, when manufacturing the heat storage particle 1 composed of a material in which the core part 10 can contract, a slurry containing a heat storage material, a binder, water, etc. is applied to the surface of the core part 10 and dried (fired if necessary), whereby the shell part 20 covering the core part 10 can be formed. Also, the shell part 20 may be formed by hybridization in which fine particles of the heat storage material are driven into the surface of the core part 10 by impact force and fixed. Further, the heat storage particle 1 may be formed by pre-molding the half-shell part 20 using a molding material containing a heat storage material, and arranging and joining the core part 10 between the two half-shell parts 20. Note that the core part 10 composed of a material that can contract can be produced by known methods such as the spray drying method and the gas atomization method.

[0042] When manufacturing the heat storage particles 1 in which the core part 10 is composed of a hollow region, a half-shell part 20 may be pre-formed using a molding material containing a heat storage material, and the two half-shell parts 20 may be joined. Further, after forming the shell part 20 on the surface of the core material such as wax by the above method, the core material may be eluted from the shell part 20. In this case, in order to make the shell part 20 airtight, after eluting the core material from the shell part 20, the eluted part may be filled with components such as a heat storage material or a binder.

[0043] <Heat storage member> As shown in FIG. 2, the heat storage member according to the embodiment of the present invention includes the above heat storage particles 1 and a storage part 100 in which the above heat storage particles 1 are accommodated. By using such a heat storage member, it becomes easy to use in heat storage devices having various structures. Further, the heat storage particles 1 accommodated in this heat storage member are less likely to undergo volume change, and even when the heat storage reaction and the heat release reaction are repeated, friction between the heat storage particles 1 is less likely to occur, so that atomization (collapse) of the heat storage particles 1 can be suppressed, and the reactivity can be maintained over a long period of time.

[0044] The storage part 100 is not particularly limited, but is preferably composed of metal or ceramics. By adopting such a configuration, the strength as a heat storage member can be ensured.

[0045] The shape of the storage part 100 is not particularly limited as long as it can accommodate the heat storage particles 1. Among them, the storage part 100 is preferably a honeycomb structure. Here, cross-sectional views of the heat storage member including the honeycomb structure as the storage part are shown in FIGS. 3A and 3B. FIG. 3A is a cross-sectional view parallel to the direction in which the cells of the honeycomb structure extend, and FIG. 3B is a cross-sectional view taken along line a-a' of FIG. 3A. As shown in FIGS. 3A and 3B, the honeycomb structure 110 has an outer peripheral wall 111 and partition walls 115 disposed inside the outer peripheral wall 111 and partitioning a plurality of cells 114 extending from a first end face 112 to a second end face 113. Further, heat storage particles 1 are accommodated in at least a part of the cells 114. The material of the honeycomb structure 110 is not particularly limited, but is preferably made of ceramics. In FIGS. 3A and 3B, an example is shown in which heat storage particles 1 are accommodated in all the cells 114, but there may be cells 114 in which the heat storage particles 1 are not accommodated. If the heat storage member uses the honeycomb structure 110 as described above as the accommodating portion 100, the heat storage reaction and the heat release reaction can be efficiently performed.

[0046] The shape (outer shape) of the honeycomb structure 110 is not particularly limited and can be various shapes. Examples of the shape (outer shape) of the honeycomb structure 110 include a cylinder, an elliptical cylinder, a quadrangular prism, or other polygonal prisms.

[0047] The thickness of the outer peripheral wall 111 is preferably larger than the thickness of the partition wall 115. By adopting such a configuration, the strength of the outer peripheral wall 111, which is likely to be damaged (for example, cracked, broken, etc.) due to external impact, thermal stress, etc., can be enhanced. The thickness of the outer peripheral wall 111 is preferably more than 0.3 mm and 10 mm or less, more preferably 0.5 mm to 5 mm, and even more preferably 1 mm to 3 mm. The thickness of the partition wall 115 is preferably 0.1 mm to 1 mm, and more preferably 0.2 mm to 0.6 mm. By setting the thickness of the partition wall 115 to 0.1 mm or more, the mechanical strength of the honeycomb structure 110 can be made sufficient. Further, by setting the thickness of the partition wall 115 to 1 mm or less, it is possible to suppress a decrease in the holding amount of the heat storage particles 1 due to a decrease in the opening area.

[0048] The partition wall 115 is preferably porous. By making the partition wall 115 porous, when the heat storage particles 1 held in the cell 114 react with the reaction medium, the reaction medium flows inside the partition wall 115, so that the contact between the heat storage particles 1 and the reaction medium proceeds promptly, and the exothermic reaction can proceed rapidly. Note that the outer peripheral wall 111 may also be porous like the partition wall 115. Here, in this specification, "porous" means having open pores and a porosity of 1% or more. The porosity can be, for example, 5% or more, 10% or more, 15% or more, or 20% or more, but is preferably 10 to 30%. Note that the "porosity" of the partition wall 115 and the outer peripheral wall 111 in this specification means the porosity measured by the mercury intrusion method in accordance with JIS R1655:2003.

[0049] The material of the honeycomb structure 110 (outer peripheral wall 111 and partition wall 115) is not particularly limited, but is preferably made of ceramics. The ceramics preferably contain SiC or alumina. By using such ceramics, the thermal conductivity can be increased.

[0050] The cell density (that is, the number of cells 114 per unit area) in the cross section of the honeycomb structure 110 perpendicular to the direction in which the cell 114 extends is not particularly limited and may be adjusted as appropriate, but is preferably in the range of 4 to 320 cells / cm 2 . By setting the cell density to 4 cells / cm 2 or more, the strength of the partition wall 115, and thus the strength of the honeycomb structure 110 itself and the effective GSA (geometric surface area) can be sufficiently ensured. Also, by setting the cell density to 320 cells / cm 2 or less, it becomes easier to transfer heat to the outside during the exothermic reaction.

[0051] The isostatic strength of the honeycomb structure 110 is not particularly limited, but is preferably more than 1 MPa, more preferably 2 MPa or more, and still more preferably 5 MPa or more. When the isostatic strength of the honeycomb structure 110 exceeds 1 MPa, the honeycomb structure 110 will have excellent durability. The isostatic strength of the honeycomb structure 110 can be measured according to the measurement method of isostatic fracture strength specified in JASO standard M505-87, which is an automotive standard issued by the Japan Society of Automotive Engineers.

[0052] The diameter (outer diameter) of the outer peripheral wall 111 in a cross section perpendicular to the direction in which the cell 114 extends is not particularly limited, but is preferably 20 to 200 mm, and more preferably 30 to 100 mm. By setting the diameter in such a range, the heat storage efficiency can be improved. When the outer peripheral wall 111 is not circular, the diameter of the largest circle inscribed in the cross-sectional shape of the outer peripheral wall 111 is taken as the diameter of the outer peripheral wall 111.

[0053] The thermal conductivity of the honeycomb structure 110 is not particularly limited, but at 25°C, it is preferably 5 W / (m·K) or more, more preferably 100 W / (m·K) or more, and still more preferably 120 W / (m·K) or more. By setting the thermal conductivity of the honeycomb structure 110 within such a range, the thermal conductivity becomes good, and heat can be efficiently transferred to the outside during the heat dissipation reaction. The value of the thermal conductivity is the value measured by the laser flash method (JIS R1611:1997).

[0054] The cell 114 containing the heat storage particles 1 may be provided with porous plugging portions on the first end face 112 side and the second end face 113 side. By adopting such a configuration, it is possible to prevent the heat storage particles 1 from falling out of the cell 114. The material of the plugging portion is not particularly limited, and the same material as that of the outer peripheral wall 111 and the partition wall 115 can be used. Also, a resin sheet or the like may be used to form the plugging portion. The method for forming the plugging portion is not particularly limited and can be carried out according to a known method.

[0055] The heat storage member can be manufactured according to a method known in the art. For example, when the honeycomb structure 110 is used as the housing part 100, it can be manufactured according to the method described below. First, the clay containing ceramic powder is extruded into a desired shape to produce a honeycomb formed body. At this time, by selecting a die and a jig of an appropriate form, the shape and density of the cell 114, the shape and thickness of the outer peripheral wall 111 and the partition wall 115, etc. can be controlled. Further, as the material of the honeycomb formed body, the above-mentioned ceramics can be used. Specifically, a binder, water and / or an organic solvent are added to a predetermined amount of ceramic powder, the obtained mixture is kneaded to form clay, and then molded to obtain a honeycomb formed body of a desired shape. Then, the obtained honeycomb formed body is dried and fired in an inert gas or vacuum under reduced pressure to obtain the honeycomb structure 110. Next, the heat storage particles 1 are accommodated (for example, filled) in at least a part of the cells 114 of the honeycomb structure 110. When providing a plugging portion, when accommodating the heat storage particles 1, a plugging portion is formed at one end of the cell 114 that accommodates the heat storage particles 1, and then the heat storage particles 1 are accommodated from the other end, and a plugging portion may be formed at the other end.

[0056] <Heat storage device> The heat storage device according to an embodiment of the present invention includes the above heat storage member and means (heating means) for heating the heat storage particles 1 in the above heat storage member. The heat storage device having such a configuration includes the above heat storage member, so that even if the heat storage reaction and the heat release reaction are repeated, the reactivity is difficult to decrease, and the heat storage reaction and the heat release reaction can be maintained for a long time.

[0057] The structure of the heat storage device is not particularly limited as long as it has the above configuration, and a known configuration can be adopted. Here, as an example, a schematic configuration diagram of a typical heat storage device is shown in FIG. 4. As shown in FIG. 4, the heat storage device includes a heat storage member 200, a case part 210, a storage tank 220, and heating means 230.

[0058] The case part 210 is a member that houses the heat storage member 200. Therefore, the case part 210 is not particularly limited as long as it has a structure capable of housing the heat storage member 200. For example, the shape of the case part 210 may be appropriately selected according to the shape of the heat storage member 200 to be housed, and can be various shapes such as a cylindrical shape or a rectangular tube shape. In addition, in FIG. 4, the case part 210 is shown as one member, but the case part 210 may be composed of two or more members. For example, the case part 210 may be configured by combining a main body part and a lid part.

[0059] The case part 210 has a communication port 211 through which the reaction medium R can be supplied from the storage tank 220 and recovered to the storage tank 220. The number of communication ports 211 may be one as shown in FIG. 4, or may be two. The material of the case part 210 is not particularly limited, but is preferably a metal from the viewpoint of manufacturability. Further, when the case part 210 is made of metal, it is also excellent in that welding with other members can be easily performed. As the material of the case part 210, for example, stainless steel, titanium alloy, copper alloy, aluminum alloy, brass, etc. can be used. Among them, stainless steel is preferable because of its high durability and reliability and low cost.

[0060] The storage tank 220 is a member through which the reaction medium R can be supplied to the case part 210 and recovered from the case part 210. That is, the storage tank 220 has a tank structure or a tank structure in which a space capable of storing the reaction medium R that chemically reacts with the heat storage material of the heat storage member 200 is provided inside, and a supply port 221 and a recovery port 222 of the reaction medium R are provided. The case part 210 (communication port 211) and the storage tank 220 (supply port 221 and recovery port 222) are connected by at least one pipe 240.

[0061] As the reaction medium R that can be stored in the storage tank 220, any substance that can cause a chemical reaction (exothermic reaction) upon contact with the heat storage material can be used, such as water, ammonia, alcohol, carbon dioxide, etc. Among these, if the reaction medium R is water, it is advantageous in terms of easy availability and easy handling. Also, when constructing the heat storage device, special facilities are not required, and it is possible to easily handle situations such as leakage, so the equipment cost and operating cost can be reduced. In particular, when the heat storage system is for in-vehicle use, the reaction medium R is preferably water from the above viewpoints.

[0062] In addition, when using water as the reaction medium R, the type of water is not particularly limited. For example, in addition to tap water (city water) and well water, distilled water, ion-exchanged water, etc. can be appropriately used. However, since the reaction medium R is repeatedly used in the heat storage device, it is preferably water (for example, ion-exchanged water) that can be used over a long period with components such as organic substances removed. By using such water, it is possible to suppress the deposition of organic substances and the like in the storage tank 220 and the case part 210, so that the operation of replacing water over a long period becomes unnecessary.

[0063] The material constituting the storage tank 220 is not particularly limited as long as it does not corrode by the reaction medium R and has sufficient strength not to break during use. Examples of typical materials can be metal materials, resin materials, or combinations of these materials.

[0064] The pipe 240 is provided with a cooling unit 250 for cooling and liquefying the gaseous reaction medium R generated during the heat storage reaction. The cooling unit 250 is not particularly limited, and a known cooling device can be used. For example, an air-cooling type cooling device having a plurality of heat dissipation plates and capable of cooling by increasing the contact area with the outside air, or a refrigerant type cooling device capable of cooling by contact with water or other refrigerants can be used.

[0065] The reaction medium R supplied from the storage tank 220 into the case portion 210 may be in a gaseous state or a liquid state. When the reaction medium R supplied from the storage tank 220 into the case portion 210 is in a gaseous state, as shown in FIG. 4, it is preferable that a pipe 240 connected to one communication port 211 of the case portion 210 branches into two in the middle and is connected to the supply port 221 and the recovery port 222 of the storage tank 220, respectively. Further, it is preferable that a valve 260 for switching the flow path of the reaction medium R flowing through the pipe 240 to the supply port 221 side or the recovery port 222 side is provided at the branch portion of the pipe 240. By switching the valve 260 so as to open the flow path on the supply port 221 side in the heat release reaction, the gaseous reaction medium R can be supplied into the case portion 210. At this time, for example, by providing a decompression mechanism for decompressing the case portion 210 side (for example, a decompression device such as a suction pump for decompressing the inside of the case portion 210), the gaseous reaction medium R can be smoothly supplied to the case portion 210. In addition, by switching the valve 260 so as to open the flow path on the recovery port 222 side in the heat storage reaction, the reaction medium R can be recovered from the inside of the case portion 210.

[0066] Further, when the reaction medium R supplied from the storage tank 220 into the case portion 210 is in a gaseous state, as shown in FIG. 4, a heater 270 for vaporizing the reaction medium R is provided in the storage tank 220. The heater 270 is electrically connected to the power source P, and the reaction medium R can be made gaseous by heating the reaction medium R with the heater 270.

[0067] The heating means 230 is not particularly limited as long as it is a mechanism capable of heating the heat storage member 200. For example, the heating means 230 can be at least one heater that contacts at least a part of the heat storage member 200, a pair of electrodes capable of applying a voltage to the heat storage member 200, and the like. Note that Fig. 4 shows an example in which a heater is provided as the heating means 230. In this heat storage device, the heat storage member 200 can be heated by heating the heater electrically connected to the power supply P. When a heater is used as the heating means 230, the type of the heater is not particularly limited, and known heaters such as a band heater, a wire heater, a sheet heater, and an infrared heater can be used.

[0068] In the heat storage device having the above structure, the heat storage reaction is performed by heating the heat storage member 200 by the heating means 230. At this time, the valve 260 is switched so as to open the flow path on the recovery port 222 side. When the heat storage member 200 is heated, the heat storage material of the heat storage member 200 changes by an endothermic reaction (for example, a dehydration reaction). For example, when Ca(OH) 2 is used as the heat storage material, it changes to CaO by an endothermic reaction (dehydration reaction). Similarly, when Mg(OH) 2 is used as the heat storage material, it changes to MgO by an endothermic reaction (dehydration reaction). CaO and MgO can maintain their states as they are even when the temperature drops as long as they are not in contact with water. The reaction medium R (water vapor) generated by the heat storage reaction (endothermic reaction) passes through the pipe 240, is cooled and liquefied in the cooling unit 250, and is recovered in the storage tank 220.

[0069] Further, in this heat storage device, the heat dissipation reaction is performed by supplying the reaction medium R to the case portion 210 and bringing the reaction medium R into contact with the heat storage material of the heat storage member 200. When the reaction medium R is brought into contact with the heat storage material, an exothermic reaction (for example, a hydration reaction) occurs and heat is generated. At this time, the valve 260 is switched so as to open the flow path on the supply port 221 side, and the reaction medium R is heated by the heater 270 to make the reaction medium R gaseous, whereby the gaseous reaction medium R can be supplied into the case portion 210. The heat generated by the heat dissipation reaction is released to the outside of the case portion 210.

Explanation of reference numerals

[0070] 1 Heat storage particles 10 Core portion 20 Shell part 100 Accommodating part 110 Honeycomb structure 111 Outer peripheral wall 112 First end face 113 Second end face 114 Cell 115 Partition wall 200 Heat storage member 210 Case part 211 Communication port 220 Storage tank 221 Supply port 222 Recovery port 230 Heating means 240 Pipe 250 Cooling part 260 Valve 270 Heater

Claims

1. A heat storage particle having a core part and a shell part covering the core part, wherein the shell part contains a heat storage material, and the core part is a heat storage particle composed of a hollow region or a shrinkable material.

2. The heat storage particle according to Claim 1, wherein the heat storage material is a chemical heat storage material.

3. The heat storage particle according to Claim 2, wherein the chemical heat storage material is a hydroxide of an alkaline earth metal.

4. The heat storage particle according to Claim 3, wherein the hydroxide of the alkaline earth metal is calcium hydroxide, magnesium hydroxide or a mixture thereof.

5. The heat storage density of the shell part is 0.2 GJ / m 3 or more, and the heat storage particles according to any one of claims 1 to 4.

6. The heat storage particle according to any one of Claims 1 to 4, wherein the porosity of the core part is 10% or more.

7. The heat storage particle according to any one of Claims 1 to 4, wherein the core part is composed of a shrinkable material and its Young's modulus is 650 GPa or less.

8. The heat storage particle according to any one of Claims 1 to 4, wherein the shrinkable material includes ceramics, metal, organic compounds or a mixture thereof.

9. A heat storage member comprising the heat storage particle according to any one of Claims 1 to 4, and a housing part in which the heat storage particle is housed.

10. The heat storage member according to Claim 9, wherein the housing part is made of metal or ceramics.

11. The heat storage member according to Claim 9, wherein the housing part is a honeycomb structure made of ceramics having an outer peripheral wall and a partition wall disposed inside the outer peripheral wall and partitioning a plurality of cells extending from a first end face to a second end face, and at least a part of the cells houses the heat storage particles.

12. The heat storage member according to Claim 11, wherein the ceramics constituting the honeycomb structure contains SiC or alumina.

13. A heat storage device comprising the heat storage member according to Claim 9, and means for heating the heat storage particles in the heat storage member. ​

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