Latent heat storage material

Abstract

To provide a latent heat storage material having a larger latent heat storage capacity.SOLUTION: A latent heat storage material includes a ceramic part made of a polycrystalline body and having a closed space formed therein and a metal part provided in the closed space and containing boron, wherein the melting point of the metal part is 1100°C or higher.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a latent heat storage medium. [Background technology]

[0002] Conventionally, an Al-Si alloy or the like has been used as a phase change material (PCM), and a latent heat storage medium has been proposed in which the PCM is surrounded by a protective layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-031507 [Patent Document 2] JP 2015-048393 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for larger amounts of latent heat storage.

[0005] An object of the present disclosure is to provide a latent heat storage material capable of storing a larger amount of latent heat. [Means for solving the problem]

[0006] According to one embodiment of the present disclosure, there is provided a latent heat storage body having a ceramic part made of a polycrystalline body in which a closed space is formed, and a metal part containing boron disposed within the closed space, wherein the melting point of the metal part is 1100°C or higher. Effect of the Invention

[0007] According to the disclosed technology, it is possible to store a larger amount of latent heat. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating a latent heat storage material according to the first embodiment. [Diagram 2] FIG. 11 is a diagram illustrating a latent heat storage material according to a second embodiment. [Diagram 3] FIG. 11 is a perspective view illustrating a latent heat storage material according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description may be omitted.

[0010] (First embodiment) A first embodiment will be described. The first embodiment relates to a latent heat storage material. Fig. 1 is a diagram illustrating a latent heat storage material according to the first embodiment. Fig. 1(a) is a perspective view, and Fig. 1(b) is a cross-sectional view.

[0011] The latent heat storage material 1 according to the first embodiment has a ceramic part 110 made of a polycrystalline body, and a metal part 120, as shown in FIGS. 1(a) and 1(b).

[0012] A closed space 113 is formed in the ceramic part 110. The ceramic part 110 and the closed space 113 are cylindrical in shape. The ceramic part 110 has, for example, a container 111 and a lid 112. The container 111 has a cylindrical shape with one end (upper end) open and the other end (lower end) closed. A female thread 111A is formed on the inner wall surface at the upper end of the container 111. The lid 112 closes the opening of the container 111. The lid 112 has a male thread 112A formed thereon to screw into the female thread 111A.

[0013] The ceramic portion 110 may contain boron nitride (BN), boron carbide (BC), aluminum nitride (AlN), a composite of aluminum nitride and boron nitride, silicon nitride (SiN), or silicon carbide (SiC), or any combination thereof. The ceramic portion 110 may be composed of boron nitride, boron carbide, aluminum nitride, a composite of aluminum nitride and boron nitride (composite ceramic), silicon nitride, or silicon carbide, or any combination thereof.

[0014] The ceramic portion 110 may contain a boride. The ceramic portion 110 may be made of a boride. The boride may be, for example, titanium boride (TiB2), zirconium boride (ZrB2), hafnium boride (HfB2), vanadium boride (VB2), niobium boride (NbB2), tantalum boride (TaB2), or lanthanum boride (LaB6), or any combination thereof.

[0015] The metal part 120 is provided in the closed space 113. In other words, the metal part 120 is sealed in the ceramic part 110. It can also be said that the metal part 120 is airtightly covered by the ceramic part 110. A plurality of metal parts 120 may be provided in the ceramic part 110. The metal part 120 contains boron (B). For example, the main component of the metal part 120 is boron. The metal part 120 contains boron at a ratio of, for example, 50% by mass or more. The metal part 120 may be composed of boron with a purity of 50% by mass or more. More preferably, the metal part 120 contains 80% by mass or more of boron and is composed of 80% by mass or more of boron. More preferably, the metal part 120 contains 99% by mass or more of boron and is composed of 99% by mass or more of boron. Metal portion 120 may contain silicon (Si), aluminum (Al), iron (Fe), copper (Cu), or cobalt (Co), or any combination thereof, in a total amount of less than 20 mass %.

[0016] For example, when the metal part 120 is composed of 80% by mass B-20% by mass Si, the phase change temperature of the metal part 120 is 1900°C or less. When the metal part 120 is composed of 80% by mass B-20% by mass Fe, the phase change temperature of the metal part 120 is 1900°C or less. When the metal part 120 is composed of 80% by mass B-20% by mass Cu, the phase change temperature of the metal part 120 is 1100°C or less. When the metal part 120 is composed of 80% by mass B-20% by mass Co, the phase change temperature of the metal part 120 is 1800°C or less.

[0017] Boron has several allotropes (α-rhombohedral, β-rhombohedral, β-tetragonal, etc.), but the boron used in the metal portion 120 is, for example, β-rhombohedral boron, which is the most stable under standard conditions.

[0018] The volume of the closed space 113 is preferably larger than the volume of the metal part 120. This is because, as described later, when the latent heat storage material 1 is used, the metal part 120 undergoes a phase change from solid to liquid, and the metal part 120 expands during this phase change.

[0019] The melting point of β-rhombohedral boron is 2180°C. When the main component of the metal part 120 is β-rhombohedral boron, a phase change between solid and liquid occurs at about 2180°C. At this temperature, the ceramic part 110 made of polycrystalline material is chemically stable. Therefore, whether the metal part 120 is solid or liquid, the ceramic part 110 can confine the metal part 120 in the closed space 113. In addition, even when used at high temperatures, the ceramic part 110 is unlikely to undergo chemical changes such as oxidation. The melting point of the metal part 120 is, for example, 1100°C or higher. The melting point of the metal part 120 is preferably 1400°C or higher, more preferably 1700°C or higher, and even more preferably 2000°C or higher. When the metal part 120 contains silicon or the like in addition to boron, the melting point of the metal part 120 may be lower than 2180°C. The melting point of the metal portion 120 can be measured, for example, by differential thermal analysis (DTA) or differential scanning calorimetry (DSC).

[0020] In the latent heat storage material 1, the metal part 120 functions as a phase change material (PCM), and since the metal part 120 contains boron, the solid-liquid phase change temperature of the metal part 120 is high, and a larger amount of latent heat can be stored. The latent heat stored in the latent heat storage material 1 can be used, for example, for direct power generation by thermophotovoltaic (TPV). The latent heat storage material 1 can be used, for example, as a thermal light source in the range of about 2100°C to 2400°C in power generation by thermophotovoltaic power.

[0021] In addition, the heat of fusion of boron per unit mass is more than 10 times that of aluminum, allowing for a significant improvement in thermal energy density.

[0022] Here, the material of the ceramic portion 110 will be described in detail.

[0023] From the viewpoint of reactivity with boron contained in metal portion 120 at high temperatures, the material of ceramic portion 110 is more preferably boron nitride, boron carbide, aluminum nitride, or a composite material of aluminum nitride and boron nitride.

[0024] As the boron nitride, hexagonal phase boron nitride is preferable. Boron nitride has excellent workability.

[0025] A composite material (composite ceramic) of boron nitride and aluminum nitride has stability as a sintered body and high thermal conductivity. A composite material of boron nitride and aluminum nitride has higher hardness and mechanical strength than hexagonal phase boron nitride. In addition, a sintered body of a composite material of boron nitride and aluminum nitride has excellent workability. The ratio of boron nitride and aluminum nitride in a composite material of boron nitride and aluminum nitride is not limited. The hardness and mechanical strength of the composite material change depending on this ratio. The microstructure of the composite material is a mixture of aluminum nitride polyhedron (tetrahedral tetradecahedron) particles and plate-shaped boron nitride particles, and the higher the ratio of plate-shaped boron nitride particles, the better the workability.

[0026] An example of the material of the ceramic portion 110 is a boride. Preferred borides include titanium boride, zirconium boride, hafnium boride, vanadium boride, niobium boride, and tantalum boride. These have a resistivity of 10 -7 Ω m~10 -8 It is a material that has electrical conductivity of about Ω·m and generates heat when electricity is applied, and can be used as a heater. When the ceramic part 110 includes titanium boride, zirconium boride, hafnium boride, vanadium boride, niobium boride, or tantalum boride, the ceramic part 110 has a protection function and a heating function of the metal part 120, and it is easy to achieve a higher heat storage density. In addition, the ceramic part 110 including titanium boride, zirconium boride, hafnium boride, vanadium boride, niobium boride, or tantalum boride can reduce the size of the equipment in a method of directly using surplus electricity to store heat (electric thermal energy: ETES).

[0027] It should be noted that the ceramic part 110 may be integrally configured. For example, the ceramic part 110 may not have a joint connected to the closed space 113. In addition, the female thread 111A of the container 111 and the male thread 112A of the lid 112 do not need to be formed, and the lid 112 may be configured to fit into the container 111.

[0028] Second embodiment A second embodiment will be described. The second embodiment relates to a latent heat storage body. Fig. 2 is a diagram illustrating a latent heat storage body according to the second embodiment. Fig. 2(a) is a perspective view, Fig. 2(b) is a cross-sectional view, and Fig. 2(c) is a top view.

[0029] In the latent heat storage body 2 according to the second embodiment, as shown in FIG. 2, two grooves 115 are formed on the outer peripheral surface of the ceramic part 110. The two grooves 115 are formed to form a substantially cylindrical shape as a whole. When viewed from a direction parallel to the long axis of the columnar metal part 120, each of the grooves 115 forms a spiral, for example, by repeating clockwise and counterclockwise alternately. An electric heater 230 is provided in each of the grooves 115. The latent heat storage body 2 has two electric heaters 230. The two electric heaters 230 have a substantially cylindrical shape as a whole. The electric heater 230 contains, for example, graphite. The electric heater 230 may be made of graphite. The electric heater 230 is an example of a heater.

[0030] Other configurations of the second embodiment are similar to those of the first embodiment.

[0031] The second embodiment can also provide the same effects as the first embodiment. In addition, since the electric heater 230 can heat the metal part 120, it is possible to convert electric energy applied from the outside into heat and store it in the latent heat storage body 2. For example, by generating heat from the electric heater 230 using surplus power, it is possible to store the surplus power as heat. The energy stored in the latent heat storage body 2 can be supplied to factories, offices, commercial buildings, etc. as energy in the form of heat, steam (pressure), or electricity (such as turbine power generation using steam pressure).

[0032] In addition, since the latent heat storage body 2 includes the electric heater 230, it is possible to reduce energy loss. For example, when the electric heater and the latent heat storage body are separated, the heat generated from the electric heater is transferred to the latent heat storage body as hot air or the like, which tends to result in energy loss, but in this embodiment, it is possible to suppress such energy loss.

[0033] Third embodiment A third embodiment will be described. The third embodiment relates to a latent heat storage material. Fig. 3 is a perspective view illustrating a latent heat storage material according to the third embodiment.

[0034] As shown in FIG. 3, the latent heat storage body 3 according to the third embodiment has a ceramic part 110 made of a polycrystalline body, a metal part 120, and an electric heater 330 capable of heating the metal part 120. The electric heater 330 is provided in the ceramic part 110. The electric heater 330 is provided between the surface of the ceramic part 110 and the surface of the metal part 120. The electric heater 330 has an approximately cylindrical shape as a whole. When viewed from a direction parallel to the long axis of the columnar metal part 120, the electric heater 330 forms a spiral, for example, by alternately repeating clockwise and counterclockwise directions. The electric heater 330 is an example of a heater.

[0035] For example, when the main component of the ceramic part 110 is aluminum nitride, the electric heater 330 contains tungsten. The electric heater 330 may contain tungsten and aluminum nitride. In this case, when manufacturing the latent heat storage body 3, for example, tungsten powder is mixed with aluminum nitride powder, and organic components such as a solvent and a binder are added to prepare a resistor paste. The part (circumferential part) perpendicular to the long axis of the metal part 120 of the electric heater 330 can be formed, for example, by a resistor paste printed on the surface of a ceramic green sheet. The part extending parallel to the long axis of the metal part 120 of the electric heater 330 can be formed, for example, by a resistor paste filled in a through hole formed in a ceramic green sheet. The resistivity of the electric heater 330 can be adjusted according to the proportion of aluminum nitride. One or more of silicon oxide, magnesium oxide, calcium carbonate, etc. may be further added to the resistor paste. These inorganic components form a liquid phase or a complex oxide phase during firing, and can improve the adhesive strength between the electric heater 330 and the ceramic portion 110 and improve the stability of the resistivity.

[0036] For example, when the main component of the ceramic part 110 is boron nitride, the electric heater 330 contains lanthanum boride. The electric heater 330 may contain lanthanum boride and boron nitride. In this case, when manufacturing the latent heat storage body 3, for example, lanthanum boride powder is mixed with boron nitride powder, and organic components such as a solvent and a binder are added to prepare a resistor paste. The part (circumferential part) perpendicular to the long axis of the metal part 120 of the electric heater 330 can be formed, for example, by a resistor paste printed on the surface of a ceramic green sheet. The part extending parallel to the long axis of the metal part 120 of the electric heater 330 can be formed, for example, by a resistor paste filled in a through hole formed in a ceramic green sheet. The resistivity of the electric heater 330 can be adjusted according to the proportion of boron nitride. One or more of silicon oxide, magnesium oxide, calcium carbonate, etc. may be further added to the resistor paste. These inorganic components form a liquid phase or a complex oxide phase during firing, and can improve the adhesive strength between the electric heater 330 and the ceramic portion 110 and improve the stability of the resistivity.

[0037] The third embodiment can also provide the same effects as the second embodiment.

[0038] Although preferred embodiments have been described in detail above, the present disclosure is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0039] 1, 2, 3 Latent heat storage material 110 Ceramic Section 113 Closed space 120 Metal Part 230, 330 Electric heating element

Claims

1. A ceramic part made of a polycrystalline material in which a closed space is formed, A metal part containing boron is provided within the aforementioned closed space, It has, The latent heat storage body has a melting point of 1100°C or higher for the metal part.

2. The latent heat storage body according to claim 1, wherein the metal part contains boron in a proportion of 99% by mass or more.

3. The latent heat storage body according to claim 1 or 2, wherein the volume of the closed space is greater than the volume of the metal part.

4. The latent heat storage body according to claim 1 or 2, wherein the ceramic portion contains boron nitride, boron carbide, aluminum nitride, a composite material of aluminum nitride and boron nitride, silicon nitride, or silicon carbide, or any combination thereof.

5. The latent heat storage body according to claim 4, wherein the material of the ceramic part is a composite material of aluminum nitride and boron nitride.

6. The latent heat storage body according to claim 1 or 2, wherein the ceramic portion contains a boride.

7. The latent heat storage body according to claim 6, wherein the boride is titanium boride, zirconium boride, hafnium boride, vanadium boride, niobium boride, tantalum boride, or lanthanum boride, or any combination thereof.

8. The latent heat storage body according to claim 1 or 2, wherein the ceramic portion contains a material that generates heat when an electric current is passed through it.

9. The latent heat storage body according to claim 1 or 2, having a heater capable of heating the metal part.

10. The latent heat storage body according to claim 9, wherein the heater is provided within the ceramic portion.

11. The heater is a latent heat storage body according to claim 9, containing tungsten, molybdenum, or both.

12. The heater is a latent heat storage body according to claim 9, which contains graphite.

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