Latent heat storage device and method for manufacturing same

Abstract

To provide a latent heat storage device which can suppress a malfunction of heat storage caused by an elution of an overcooling prevention agent to a latent heat storage material, can arrange the overcooling prevention agent in the vicinity of heat transmission means, and can be made compact in its size, and its manufacturing method.SOLUTION: A latent heat storage device 1A comprises: a seed crystal part 22 which accommodates an overcooling prevention medium 12 for carrying a salt of a water-insoluble or hardly-soluble alkali earth metal; a heat storage part 21 accommodating a latent heat storage material 24 which intermittently communicates with the seed crystal part; a heat transmission part to the latent heat storage part; and a valve 10 having a seal part 11 which moves between the seed crystal part and the heat storage part so as to be openable and closable at a tip. A base end of the valve is arranged at the seed crystal part side of the latent heat storage device, and the overcooling prevention medium is arranged in a region of the valve at the base end side rather than the seal part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a latent heat storage device and a method for manufacturing the same. [Background technology]

[0002] Conventionally, various heat storage devices have been proposed that temporarily store thermal energy discharged from a moving body such as a vehicle in a heat storage material and use it when starting the engine in order to promote warm-up, improve fuel efficiency, purify exhaust gas, and improve heating performance.

[0003] For example, Patent Document 1 describes a heat storage device that includes a heat storage container containing a latent heat storage material that creates a supercooled state when allowed to cool after heating and melting, a heat transfer means to the heat storage material, a seed crystal container containing a crystal nucleus forming material that collapses the supercooled state, a communication means that connects the inside of the heat storage container and the seed crystal container, and a communication interruption means for this communication means. This heat storage device is characterized in that the crystal nucleus forming material is filled in the seed crystal container at the location furthest from the communication means, and the remaining space is filled with a latent heat storage material.

[0004] The heat storage principle of supercooled latent heat storage materials as described in Patent Document 1 is that when the material is heated above its melting point in a solid phase, it transforms into a liquid phase. This liquid phase does not recrystallize even when cooled below the melting point, but continues to remain in a supercooled state, and the heat absorbed during heating is stored as latent heat. When it is desired to use this absorbed heat, the material is brought into contact with a crystal nucleus forming material that has the function of breaking down the supercooled state, causing the material to recrystallize, and the stored latent heat can be extracted in an extremely short time as dissipated heat accompanying the state change from liquid to solid. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 63-68418 Summary of the Invention [Problem to be solved by the invention]

[0006] In this way, seed crystals are necessary to nucleate the heat storage material in the supercooled liquid phase at any time and change it to a solid phase. In order to stably maintain the seed crystals, it is known to use a supercooling prevention agent that forcibly changes the heat storage material to a solid phase below the melting point.

[0007] However, in the heat storage device described in Patent Document 1, if a supercooling prevention agent is used in the seed crystal container, the heat storage container and the seed crystal container are connected during heat release, and when the heat storage material in the heat storage container flows toward the seed crystal container, if the supercooling prevention agent dissolves into the heat storage material, the supercooling prevention agent will be mixed into the heat storage container, causing the heat storage container to be unable to store heat.

[0008] In particular, if the temperature rises not only in the heat storage container but also in the seed crystal container during heat transfer to the heat storage material, the dissolution of the supercooling prevention agent will become significant, so the seed crystal container containing the supercooling prevention agent must be positioned away from the heat storage container, which poses the problem that the heat storage device cannot be made compact.

[0009] In view of the above problems, the present invention aims to provide a latent heat storage device and a manufacturing method thereof that can prevent heat storage problems caused by the dissolution of a supercooling prevention agent into a latent heat storage material, and that allows the supercooling prevention agent to be placed in the vicinity of a heat transfer means, thereby making the latent heat storage device compact. [Means for solving the problem]

[0010] In order to achieve the above object, one aspect of the present invention is a latent heat storage device comprising: a seed crystal portion containing a supercooling prevention medium carrying a salt of an alkaline earth metal that is insoluble or poorly soluble in water; a heat storage portion containing a latent heat storage material that is in intermittent communication with the seed crystal portion; a heat transfer portion to the latent heat storage material; and a valve having at its tip a seal portion that moves between the seed crystal portion and the heat storage portion in an openable and closable manner, the base end of the valve being positioned on the seed crystal portion side of the latent heat storage device, and the supercooling prevention medium being positioned in a portion of the valve closer to the base end than the seal portion.

[0011] In another aspect, the present invention provides a method for manufacturing a latent heat storage device, the method including the steps of: applying uncured sealing material to a tip of a valve that moves between a seed crystal portion and a heat storage portion of the latent heat storage device to open and close the space between the seed crystal portion and the heat storage portion, the tip portion being a contact portion that is a region that comes into contact with a part of the latent heat storage device to close the space between the seed crystal portion and the heat storage portion, and a base end portion that is a region on the base end side of the contact portion; injecting a salt of an alkaline earth metal that is insoluble or poorly soluble in water into a surface of the uncured sealing material applied to the base end portion to embed a portion of the salt; and curing the uncured sealing material to form a seal portion at the contact portion and form a supercooling prevention medium at the base end portion. Effect of the Invention

[0012] Thus, according to the present invention, by storing a supercooling prevention medium carrying a supercooling prevention agent in the seed crystal section of the latent heat storage device, heat storage problems caused by the supercooling prevention agent dissolving into the latent heat storage material can be prevented, and this supercooling prevention medium can be placed in the vicinity of the heat transfer section, thereby making the latent heat storage device compact. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a schematic diagram of an embodiment of a latent heat storage device according to the present invention. [Diagram 2] 2 is a cross-sectional view showing a schematic state of the latent heat storage device shown in FIG. 1 during heat dissipation. FIG. [Diagram 3]FIG. 4 is a cross-sectional view showing a schematic diagram of another embodiment of a latent heat storage device according to the present invention. [Figure 4] 4 is a cross-sectional view showing a schematic state of the latent heat storage device shown in FIG. 3 during heat dissipation. FIG. [Diagram 5] FIG. 4 is a cross-sectional view illustrating a schematic diagram of still another embodiment of a latent heat storage device according to the present invention. [Figure 6] 6 is a cross-sectional view showing a schematic state of the latent heat storage device shown in FIG. 5 during heat dissipation. [Figure 7] FIG. 2 is a flow chart for explaining an embodiment of a method for manufacturing a latent heat storage device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a latent heat storage device and a manufacturing method thereof according to the present invention will be described with reference to the accompanying drawings.

[0015] [Latent heat storage device of the first embodiment] 1, the latent heat storage device 1A of the first embodiment mainly includes a needle valve 10 and a main container 20 that houses a seal portion 11 of the needle valve 10. The main container 20 mainly includes a cylindrical seed crystal portion 22 that houses a supercooling prevention medium 12 that carries a salt of an alkaline earth metal that is insoluble or poorly soluble in water, and a cylindrical heat storage portion 21 that houses a latent heat storage material 24 that is in intermittent communication with the seed crystal portion. The seed crystal portion 22 also houses a latent heat storage material 24.

[0016] The latent heat storage device 1A is provided with a narrowed portion 23 having an inner diameter narrower than the heat storage portion 21 and the seed crystal portion 22 at the center position of the main container 20, thereby dividing the inside of the main container 20 into the heat storage portion 21 and the seed crystal portion 22. In addition, the seed crystal portion 22 is provided with a base end side of a valve 10 having a seal portion 11 at its tip that moves to open and close the narrowed portion 23.

[0017] The valve 10 includes, in order from its tip, a conical seal portion 11 larger than the inner diameter of the narrowed portion 23, a supercooling prevention medium 12, and a spindle 13 for moving the seal portion 11 so as to be openable and closable relative to the narrowed portion 23. The angle of the conical surface of the seal portion matches the angle of the conical surface connecting the narrowed portion 23 and the seed crystal portion 22. The opening and closing movement of the seal portion 11 relative to the narrowed portion 23 is controlled by a control circuit (not shown) of the latent heat storage device 1A.

[0018] The surface of the sealing portion 11 is formed of an elastic body, and is capable of closing the narrowed portion 23 by pressing against the narrowed portion 23 of the main container 20. The supercooling prevention medium 12 has a surface formed of the same elastic body as the sealing portion 11, and the surface of this elastic body carries a supercooling prevention agent, that is, a salt of an alkaline earth metal that is insoluble or poorly soluble in water.

[0019] As the alkaline earth metal, strontium, barium, etc. are preferred from the viewpoint of providing an excellent supercooling prevention effect as a supercooling prevention agent and generating a salt that is insoluble or poorly soluble in water. In addition, as the salt of an alkaline earth metal that is insoluble or poorly soluble in water, strontium sulfate, strontium carbonate, barium sulfate, barium carbonate, etc. are preferred. In this way, since the supercooling prevention agent, which is a salt that is insoluble or poorly soluble in water, is supported on the supercooling prevention medium 12, it is possible to prevent the supercooling prevention agent from flowing out of the supercooling prevention medium 12 and moving through the narrowed portion 23 to the heat storage portion 21 that accommodates the latent heat storage material 24.

[0020] In this specification, "water-insoluble" refers to a substance that has a solubility of 0.01 g or less in 100 g of water at room temperature (25°C). "Slightly soluble in water" refers to a substance that has a solubility of 0.1 g or less but more than 0.01 g in 100 g of water at room temperature (25°C). Strontium sulfate has a solubility of 0.014 g / 100 ml of water, making it poorly soluble in water. Strontium carbonate has a solubility of 0.0011 g / 100 ml of water, making it insoluble in water. Barium sulfate has a solubility of 2.5 x 10 -4 g / 100 ml of water and is insoluble in water.

[0021] The elastic body of the seal portion 11 is not particularly limited as long as it is a material that can adhere closely to the inner surface of the narrowed portion 23 so as to block the communication between the latent heat storage material 24 and the heat storage portion 21 and the seed crystal portion 22, and examples of the material include rubber, elastomer, and resin. In particular, rubber is preferable because of its flexibility and high durability against repeated heating and cooling. Specific examples of rubber include silicone rubber, nitrile rubber, fluororubber, and butyl rubber. By using a material with excellent flexibility, it is possible to reduce the volume change caused by the phase change of the latent heat storage material 24 and the generation of stress caused by the phase change of the latent heat storage material 24 during the crystal growth process.

[0022] It is also preferable to use a seal material (i.e., an elastic body) of the seal portion 11 and a carrier carrying the supercooling prevention agent of the supercooling prevention medium 12 that are integrally formed from the same material. By integrally forming the seal portion 11 and the supercooling prevention medium 12, the number of parts of the latent heat storage device 1A can be reduced, thereby lowering manufacturing costs, and the supercooling prevention medium 12 can expose crystals of the supercooling prevention agent on its surface while ensuring the sealing performance of the seal portion 11.

[0023] The latent heat storage material 24 is not particularly limited as long as it is a substance that changes into a liquid phase when heated above its melting point in a solid phase, and continues to maintain the liquid phase in a supercooled state even when cooled below its melting point, and can store the heat absorbed during heating as latent heat. For example, calcium chloride hydrate, sodium acetate hydrate, sodium sulfate hydrate, etc. are preferred.

[0024] The main container 20 may be one that can withstand heating and cooling for changing the state of the latent heat storage material 24 between the solid phase and the liquid phase, and may use the material and structure of a container for accommodating a latent heat storage material in a conventional latent heat storage device. For example, the material may be stainless steel, aluminum alloy, brass, etc., which have good thermal conductivity, and the structure may be a rectangular parallelepiped or any other three-dimensional shape. In addition, a heat transfer part (not shown), such as a fin for increasing the heat transfer area, is attached to the outer periphery of the latent heat storage device 1A as a heat transfer means to the latent heat storage material 24. As the fin, a fin-shaped fin, a corrugated fin, etc. may be used.

[0025] The heat storage and heat release of the latent heat storage device 1A having such a configuration will be described with reference to Figures 1 and 2. First, in the latent heat storage device 1A in a state where heat storage is completed and heat release is not yet performed, as shown in Figure 1, the needle valve 10 is closed and the seal part 11 is in close contact with the narrowed part 23. A liquid phase latent heat storage material 24L is contained in the heat storage part 21. Since a supercooling prevention medium 12 is disposed in the seed crystal part 22, the inside of the seed crystal part 22 contains a solid phase latent heat storage material 24S, i.e., a seed crystal.

[0026] Next, when dissipating heat from the latent heat storage device 1A, as shown in Fig. 2, the needle valve 10 is moved to open the narrowed portion 23, so that the liquid-phase latent heat storage material 24L in the heat storage portion 21 flows through the flow path 25 of the narrowed portion 23 into the seed crystal portion 22 and comes into contact with the solid-phase latent heat storage material 24S that serves as a seed crystal in the seed crystal portion 22. As a result, the liquid-phase latent heat storage material 24L nucleates and becomes solid, causing heat dissipation.

[0027] Until the heat dissipation is completed, the latent heat storage material 24S in the heat storage section 21 is in the solid phase. In this state, heat storage in the latent heat storage device 1A is started. Since the latent heat storage material 24S in both the heat storage section 21 and the seed crystal section 22 is in the solid phase, the needle valve 10 cannot be closed.

[0028] When the heat storage is completed, the latent heat storage material 24 in the heat storage section 21 and the seed crystal section 22 are both in the liquid phase because they have been heated to above their melting points. When this state is reached, the needle valve 10 can be closed.

[0029] Thereafter, when the latent heat storage device 1A is cooled to below the melting point, the latent heat storage material 24L in the seed crystal portion 22 changes to a solid phase because the supercooling prevention medium 12 is disposed therein. Therefore, the latent heat storage material 24L again becomes ready to release heat, as shown in Fig. 1. In this way, the latent heat storage device 1A of the first embodiment can repeatedly release and store heat.

[0030] If the supercooling prevention agent is not supported and the supercooling prevention agent gets mixed into the latent heat storage material, when heat storage is completed, a seed crystal consisting of the latent heat storage material and the supercooling prevention agent will remain in the liquid-phase latent heat storage material 24L in the seed crystal 22, and this seed crystal may flow through the flow path 25 of the narrowed portion 23 to the liquid-phase latent heat storage material 24L in the heat storage section 21. If the supercooling prevention agent gets mixed into the heat storage section 21, the liquid-phase latent heat storage material 24L in the heat storage section 21 will not reach a supercooled state, and a problem will occur in which it will not be able to store heat.

[0031] In the latent heat storage device 1A of the first embodiment, a supercooling prevention agent is stored in the seed crystal section 22 as a supercooling prevention medium 12 carrying the supercooling prevention agent, and since the supercooling prevention agent is a salt that is insoluble or poorly soluble in water, it does not flow into the latent heat storage material 24, and therefore the supercooling prevention agent can be prevented from being mixed into the heat storage section 21.

[0032] The latent heat storage device of the present invention is not limited to the first embodiment described above, and can be in a wide variety of embodiments. For example, the tip may be a valve that is not needle-shaped, as in the latent heat storage device 1B of the second embodiment shown in Figs. 3 and 4, and the latent heat storage device 1C of the third embodiment shown in Figs. 5 and 6, and the seal part of the tip and the supercooling prevention medium do not have to be integrally formed of the same material. A more detailed explanation will be given below. Note that the explanation of the same configuration as the first embodiment is omitted.

[0033] [Second embodiment] 3, the latent heat storage device 1B of the second embodiment mainly includes a valve 30 and a main container 40 that houses a seal portion 31 of the valve 30. An O-ring 34 is provided between the valve 30 and the main container 40 to ensure sealing performance.

[0034] Valve 30 comprises, in order from its tip, a conical seal portion 31 that is wider on the tip side, a supercooling prevention medium 32, and a spindle 33 for moving seal portion 31 so as to be able to open and close. Supercooling prevention medium 32 is disposed at a portion of spindle 33 adjacent to seal portion 31.

[0035] The main container 40 mainly includes a cylindrical seed crystal portion 42 that houses the supercooling prevention medium 32, and a cylindrical heat storage portion 41 that houses a latent heat storage material 44 that is in intermittent communication with the seed crystal portion. The seed crystal portion 42 has a narrower inner diameter than the heat storage portion 41.

[0036] The latent heat storage device 1B is provided with a constricted portion 43 having a truncated cone shape at the center of the main container 40. The angle of the conical surface of the seal portion 31 matches the angle of the conical surface of the constricted portion 43.

[0037] In the latent heat storage device 1B having such a configuration, before heat dissipation, as shown in Fig. 3, the valve 30 is closed and the seal portion 31 is in close contact with the narrowed portion 43. A liquid phase latent heat storage material 44L is contained in the heat storage portion 41. Since the supercooling prevention medium 32 is disposed in the seed crystal portion 42, the inside of the seed crystal portion 42 contains a solid phase latent heat storage material 44S, i.e., a seed crystal.

[0038] Next, when dissipating heat from the latent heat storage device 1B, as shown in Figure 4, the valve 30 of the latent heat storage device 1B is moved to open the narrowing section 43, so that the liquid phase latent heat storage material 44L in the heat storage section 41 flows through the flow path 45 of the narrowing section 43 into the seed crystal section 42 and comes into contact with the solid phase latent heat storage material 44S that serves as a seed crystal in the seed crystal section 42, and the liquid phase latent heat storage material 44L nucleates and becomes solid, causing heat to be dissipated.

[0039] When the heat dissipation and further heat storage are completed, the latent heat storage material 44 in the heat storage section 41 and the seed crystal section 42 is above its melting point and in liquid phase, so the valve 30 is closed. Thereafter, when the latent heat storage device 1B is cooled below its melting point, the latent heat storage material 44L in the seed crystal section 42 changes state to a solid phase because the supercooling prevention medium 32 is disposed therein. Therefore, as shown in FIG. 3, the latent heat storage device 1B is again in a state of preparation for heat dissipation. In this way, the latent heat storage device 1B of the second embodiment can repeatedly perform heat dissipation and heat storage.

[0040] [Third embodiment] 5, the latent heat storage device 1C of the third embodiment mainly includes a valve 50 and a main container 60 that houses a seal portion 51 of the valve 50. A grommet 54 is provided between the valve 50 and the main container 60 to ensure sealing performance.

[0041] Valve 50 includes, in order from its tip, a plate-shaped seal portion 51, a supercooling prevention medium 52, and a spindle 53 for moving seal portion 51 so as to be able to open and close. Supercooling prevention medium 52 is disposed at a portion of spindle 53 adjacent to seal portion 51.

[0042] The main container 60 mainly includes a seed crystal portion 62 that stores the supercooling prevention medium 52, and a cylindrical heat storage portion 61 that stores a latent heat storage material 64 that is in intermittent communication with the seed crystal portion. The seed crystal portion 62 is a portion surrounded by the back surface 51B of the seal portion 51 and the inner surface 55 of the grommet 54.

[0043] In the latent heat storage device 1C having such a configuration, before heat dissipation, as shown in Fig. 5, the valve 50 is closed and the back surface 51B of the seal portion 51 is in close contact with the inner surface 55 of the grommet 54. A liquid phase latent heat storage material 64L is contained in the heat storage portion 61. Since the supercooling prevention medium 52 is disposed in the seed crystal portion 62, the inside of the seed crystal portion 62 contains a solid phase latent heat storage material 64S, i.e., a seed crystal.

[0044] Next, when dissipating heat from the latent heat storage device 1C, as shown in Figure 6, the valve 50 is moved to open the space between the seal portion 51 and the grommet 52, so that the liquid phase latent heat storage material 64L in the heat storage portion 61 flows through the flow path 65 between them into the seed crystal portion 62 and comes into contact with the solid phase latent heat storage material 64S which has become a seed crystal in the seed crystal portion 62, and the liquid phase latent heat storage material 64L nucleates and becomes solid, causing heat to be dissipated.

[0045] When heat dissipation and further heat storage are completed, the latent heat storage material 64 in the heat storage section 61 and the seed crystal section 62 is above its melting point and in liquid phase, so the valve 50 is closed. Thereafter, when the latent heat storage device 1C is cooled below its melting point, the latent heat storage material 64L in the seed crystal section 62 changes state to a solid phase because the supercooling prevention medium 52 is disposed therein. Therefore, as shown in FIG. 5, the latent heat storage device 1C is again in a state of preparation for heat dissipation. In this way, the latent heat storage device 1C of the third embodiment can repeatedly perform heat dissipation and heat storage.

[0046] Next, an embodiment of a method for manufacturing a latent heat storage device according to the present invention will be described.

[0047] As shown in Fig. 7, the manufacturing method of the latent heat storage device of this embodiment includes a step of mixing an aqueous solution 71 (also simply called "cation-containing aqueous solution") containing an alkaline earth metal cation and an aqueous solution 72 (also simply called "anion-containing aqueous solution") containing an anion that reacts with the alkaline earth metal cation to produce a salt that is insoluble or poorly soluble in water (Fig. 7(a)), a step of reacting these aqueous solutions to produce a precipitate of an alkaline earth metal salt 73 (supercooling prevention agent) that is insoluble or poorly soluble in water (Fig. 7(b)), a step of applying an uncured sealant 74 to the entire tip 81 of the needle valve 80 (Fig. 7(c)), a step of pressurizing the supercooling prevention agent 73 onto the surface of the uncured sealant 74 at the base end portion 83 of the tip 81 (Fig. 7(d)), and a step of curing the uncured sealant (not shown). Each step will be described in more detail.

[0048] In the mixing step, as shown in Fig. 7(a), an aqueous solution 71 containing alkaline earth metal cations is placed in a container 70 such as a screw bottle. As described above, the alkaline earth metal is, for example, strontium or barium. As the aqueous solution, from the viewpoint of producing a salt that is insoluble or poorly soluble in water, an aqueous solution of an alkaline earth metal chloride, an aqueous solution of an alkaline earth metal hydroxide, an aqueous solution of an alkaline earth metal nitrate, or the like is preferable. The concentration of the cation-containing aqueous solution 71 is not particularly limited, but is, for example, preferably 0.1 to 1.5 mol / L, more preferably 1 to 1.2 mol / L.

[0049] Then, an aqueous solution 72 containing anions that react with the cations of the alkaline earth metal to produce a salt that is insoluble or poorly soluble in water is placed in the container 10. Such anions vary depending on the type of the cation-containing aqueous solution 71, but are preferably, for example, sulfate ions, carbonate ions, oxide ions, etc. The concentration of the anion-containing aqueous solution 72 may be a theoretical amount required to produce a salt that is insoluble or poorly soluble in water, in accordance with the concentration of the cation-containing aqueous solution 71.

[0050] In the precipitate formation step, as shown in Fig. 7(b), alkaline earth metal cations in the cation-containing aqueous solution 71 react with anions in the anion-containing aqueous solution 72, and a water-insoluble or poorly soluble alkaline earth metal salt 73 precipitates. This water-insoluble or poorly soluble alkaline earth metal salt 73 functions as a supercooling inhibitor. As an example of this reaction, the reaction formula when the cation-containing aqueous solution 71 is an aqueous strontium chloride solution and the anion-containing aqueous solution 72 is dilute sulfuric acid is shown below. In this reaction, strontium sulfate is formed as the supercooling inhibitor. SrCl2+H2SO4→SrSO4+2HCl

[0051] The precipitate of the water-insoluble or poorly soluble alkaline earth metal salt 73 is filtered and then dried to obtain granules of the water-insoluble or poorly soluble alkaline earth metal salt 73. The particle size of the granules is not particularly limited, but may be in the range of 10 to 1000 μm, for example.

[0052] In the sealant application process, as shown in FIG. 7(c), an uncured sealant 74 is applied to the entire tip 81 of the needle valve 80 (including a contact portion 82 including an area in contact with a part of the latent heat storage device to close the gap between the seed crystal portion of the latent heat storage device and the heat storage portion, and a base end portion 83 which is an area on the base end side of the contact portion 82). The sealant hardens to become an elastic body. As described above, examples of the elastic body include rubber, elastomer, and resin, and rubber is particularly preferable, specifically silicone rubber.

[0053] The uncured sealant 74 can be applied in a uniform thickness by, for example, spraying or coating on the surface of the tip 81 of the needle valve 80. The thickness of the uncured sealant 74 is not particularly limited, but may be in the range of 0.1 to 10 mm, for example.

[0054] In the supercooling prevention agent press-in process, as shown in Fig. 7(d), granules of water-insoluble or poorly soluble salt 73 are press-injected into the surface of uncured sealing material 74 only at the base end portion 83 of the tip portion 81. This allows a portion of the granules of water-insoluble or poorly soluble salt 73 to be embedded in uncured sealing material 74. If the amount of water-insoluble or poorly soluble salt 73 is in the range of, for example, 0.1 to 10 g per unit area at the base end portion 83, it can function sufficiently as a supercooling prevention agent for the latent heat storage device.

[0055] In the sealant hardening process, the unhardened sealant 74 is hardened, so that a seal portion can be formed at the contact portion 82 of the tip portion 81 of the valve that moves between the seed crystal portion and the heat storage portion of the latent heat storage device in an openable and closable manner, and a supercooling prevention medium can be formed at the base end portion 83. The sealant can be hardened, for example, by mixing two liquids, by heating, or by moisture in the air (room temperature hardening), among which room temperature hardening is particularly preferable. When it comes into contact with moisture at room temperature, it hardens and becomes an elastic body, so it is easy to mold, and can be molded with high precision, and therefore excellent vibration resistance, impact resistance, and heat resistance can be ensured in the seal portion. The material of the unhardened sealant is selected according to the type of hardening. For example, it is preferable to use a room temperature hardening silicone material.

[0056] The valve thus obtained is incorporated into the main container of the latent heat storage device, whereby the latent heat storage device of the present invention can be manufactured. EXAMPLES

[0057] Examples of the present invention will now be described.

[0058] [Preparation of supercooling prevention medium] A 10 wt% dilute sulfuric acid solution was added to an aqueous solution of strontium chloride (SrCl2) to cause a precipitation of strontium sulfate (SrSO4). The precipitate of strontium sulfate was filtered with filter paper and dried to obtain powdered strontium sulfate. Next, 1.0 g of room temperature curing silicone rubber (manufactured by ThreeBond Co., Ltd., product name: silicone liquid gasket, product number: TB1215) was added to 0.003 g of the powdered strontium sulfate, and mixed, and molded into granular material with a particle size of about 5 to 10 mm. Then, the mixture was left to stand sufficiently to harden, and a silicone rubber body carrying strontium sulfate (i.e., a supercooling prevention medium) was obtained.

[0059] [Evaluation test of supercooling prevention effect] The silicone rubber (approximately 0.03 g) carrying the strontium sulfate thus obtained and calcium chloride hexahydrate (CaCl2·6H2O) (approximately 20 g) as a latent heat storage material were placed in a screw bottle and heated to above 30°C, which is the melting point of calcium chloride hexahydrate. The screw bottle was then placed on a cooling plate set at 2-5°C using a chiller, and it was investigated whether nucleation would occur. The cooling plate was immersed in water to promote heat transfer between the cooling plate and the screw bottle, and the bottom of the placed screw bottle was immersed in water to efficiently cool it. This heating and cooling process was repeated 15 times (n=15), and the number of times nucleation occurred was investigated.

[0060] In addition, the change in shape of the supercooling prevention medium due to repeated heating and cooling (the presence or absence of cracks or fragments) was observed to investigate its durability. In order to confirm that strontium sulfate had not leaked out of the silicone rubber, the supercooling prevention medium was removed from the screw bottle after the test, and it was also investigated whether the latent heat storage material would become supercooled in this state. For comparison, the same heating and cooling cycle was repeated for activated carbon, and the change in shape was observed.

[0061] As a result, the silicone rubber supported by strontium sulfate nucleated every time it was tested 15 times, and maintained its supercooling prevention effect throughout the test. In terms of durability, no cracks occurred throughout the test. It was also observed that the latent heat storage material, from which the supercooling prevention medium had been removed after the test, went into a supercooled state on the cooling plate, and it was confirmed that strontium sulfate had not leaked out of the silicone rubber. On the other hand, the activated carbon cracked after 10 repetitions.

[0062] From the test results, it is believed that even if powdered strontium sulfate is added to silicone rubber and solidified, some of the strontium sulfate crystals are exposed from the surface of the silicone rubber, preventing the surrounding calcium chloride hexahydrate from supercooling. It was also confirmed that the rubber material is less likely to crack when repeatedly heated and cooled. Furthermore, from the results of the outflow test, it is presumed that strontium sulfate is poorly soluble in water, and therefore, if it is a salt that is insoluble or poorly soluble in water, it will not flow out of the silicone rubber into the latent heat storage material even if it is repeatedly heated and cooled. Therefore, it is presumed that strontium carbonate, which is insoluble in water, can also be used as a supercooling prevention medium of the present invention, with the same effect as strontium sulfate.

[0063] In addition, barium sulfate and barium carbonate have the same orthorhombic crystal structure as strontium sulfate and strontium carbonate, and the unit lattice is very similar to that of strontium sulfate and strontium carbonate, so they are presumed to have a supercooling prevention effect. Furthermore, barium sulfate and barium carbonate are insoluble in water. Therefore, it is presumed that barium sulfate and barium carbonate can also obtain the same effect as strontium sulfate and strontium carbonate as the supercooling prevention medium of the present invention. [Explanation of symbols]

[0064] 1 Latent heat storage device 10 Needle Valve 11, 31, 51 Seal part 12 Supercooling prevention medium 13 Spindle 14 Supercooling prevention agent 15 Carrier (sealing material) 20, 40, 60 Main container 21, 41, 61 Heat storage section 22, 42, 62 Seed crystal part 23 Stenosis 24 Latent heat storage material 25, 45, 65 flow channels 30, 40 valve 34 O-ring 54 Grommet 70 Screw Bottle 71 Aqueous solutions containing alkaline earth metal cations 72 Aqueous solutions containing anions that form salts that are insoluble or poorly soluble in water 73 Salts of alkaline earth metals that are insoluble or sparingly soluble in water 74 Uncured sealant

Claims

1. a seed crystal portion containing a supercooling prevention medium carrying a salt of an alkaline earth metal that is insoluble or poorly soluble in water; A heat storage section containing a latent heat storage material that is in intermittent communication with the seed crystal section; A narrowed portion dividing the seed crystal portion and the heat storage portion; A heat transfer portion to the latent heat storage material; a valve having a seal portion at a tip thereof that moves between the seed crystal portion and the heat storage portion in an openable and closable manner; A latent heat storage device comprising: A base end of the valve is disposed on the seed crystal side of the latent heat storage device, and the supercooling prevention medium is disposed in a portion of the valve on the base end side of the seal portion, The narrowed portion can be closed by pressing the sealing portion against the narrowed portion, A latent heat storage device, wherein a portion of the water-insoluble or poorly soluble alkaline earth metal salt is exposed from a surface of the supercooling prevention medium.

2. 2. The latent heat storage device according to claim 1, wherein the seal material of the seal portion and the carrier carrying the alkaline earth metal salt of the supercooling prevention medium are integrally formed from the same material.

3. 3. The latent heat storage device according to claim 2, wherein the material is a room temperature curing silicone rubber.

4. a step of applying an uncured sealant to a contact portion of a tip of a valve that moves between a seed crystal portion and a heat storage portion of a latent heat storage device so as to be capable of opening and closing the space between the seed crystal portion and the heat storage portion and a base end portion that is a region on the base end side of the contact portion; a step of injecting a salt of an alkaline earth metal that is insoluble or poorly soluble in water into a surface of the uncured sealing material applied to the base end portion to embed a part of the surface; hardening the unhardened seal material to form a seal at the contact portion and to form a supercooling prevention medium at the base end portion; A method for manufacturing a latent heat storage device comprising the steps of:

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