JPH0261463A - Latent-heat storage device - Google Patents

Abstract

PURPOSE:To enhance safety and achieve stabilization in the performance of providing heat stored by disposing heat exchanger tubes, through which fluid to be heated is passed, above the top ends of capsules containing latent heat-storing material and by filling the heat storage tank with a fluid thermal medium, which vaporizes at a temperature below that of the heat stored, to a level below the heat exchanger tubes. CONSTITUTION:Heat exchanger tubes 3 are disposed in the form of two coils one coil above the other and fixed to the undersides of umbrellas 4 and connected to a feedwater pipe 5 and a tube 6 for collecting hot water or steam either in series or in parallel therebetween. The heat storage tank is enclosed by a heat-insulating layer 7 over the outer surface and contains a fluid heating medium 8 in the lower part of the space inside. This fluid heating medium 8 is a substance which vaporizes at a temperature below that of the heat stored and does not assume a solid state even at the lowest temperature that the heat storage device can ever reach; it gets heated by radiant heat from capsules 2 and, upon reaching a boiling point, it vaporizes and rises in the interstices between the capsules 2; it turns to superheated steam under heat at the surfaces of the capsules 2 and by contact with the heat exchanger tubes 3 performs heat exchange with the water therein. The fluid thermal medium liquefied through loss of heat is scattered along the undersides of the umbrellas 4, vaporized and made to transfer heat again.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a latent heat storage device that stores heat using a latent heat storage material and extracts and utilizes the heat as needed.

Conventional technology A heat storage device that stores unsteady energy such as late-night electricity or industrial waste heat as heat and extracts that heat as hot water or steam as needed has a large amount of heat storage per unit mass and is suitable for heat extraction. Among them, a latent heat storage device using a latent heat storage material that utilizes the latent heat of fusion of a substance is advantageous because the temperature does not change.

One method of latent heat storage is to place a large number of capsules filled with latent heat storage material in a heat storage tank, and then heat a fluid such as water to be used between the capsules and convert the heat from the heat storage material inside the capsules into the fluid. What is communicated is known. (precedent example; '84
New Technology Symposium PART 5 Development and Examples of the Latest Heat Storage and Temperature/Heat Exchange Technology "Research and Development of Japanese Heat Storage Technology" (Japan Management Association) Since the capsule is in contact with the fluid to be used (for example, water), if cracks or pinholes occur in the capsule due to corrosion due to thermal stress, the latent heat storage material will be mixed into the fluid to be used. Caustic soda, which is considered to be a promising latent heat storage material, is designated as a deleterious substance under the Poisonous and Deleterious Substances Control Law (permissible concentration 2 mg/rn').
Therefore, when caustic soda is used as the latent heat storage material, the latent heat storage device having the above configuration poses a safety problem.

In order to solve this problem, heat exchange is performed by bringing the heat transfer fluid into contact with the latent heat storage material capsule without directly contacting the use fluid with the latent heat storage material capsule, so that the use fluid is contained in the flow path or space of the heat transfer fluid. Install heat exchange piping that flows inside,
It has been proposed to recover heat stored in a latent heat storage material into a utilization fluid via a heat transfer fluid.

Conventionally, the above-mentioned heat transfer fluid is a special fluid that maintains a liquid state within the temperature range reached by the heat storage device.
Such liquids are expensive, and miniaturization must be considered from an economic standpoint. If the temperature fluctuates during the heat extraction process, or if the heat transfer tubes are located at the top of the heat storage tank and the amount of heat transfer fluid is insufficient, the heat transfer tubes will not be uniformly contacted with the heat transfer fluid, resulting in poor heat transfer. However, this method has the disadvantage that it cannot be performed stably and efficiently.

Problems to be Solved by the Invention The present invention solves the above-mentioned drawbacks of the conventional latent heat storage device having the above-mentioned configuration, which uses a heat transfer fluid to perform heat exchange in consideration of stability. It is an object of the present invention to provide a heat storage device that can maintain a constant temperature of the heat transfer fluid and uniformly contact the heat transfer tubes in the process of extracting the stored heat, thereby stably and efficiently extracting the heat. purpose.

Means for Solving the Problems In order to solve the above problems, the present invention provides a heat storage device having the above structure, in which the heat transfer tube through which the fluid to be heated flows is located above the upper end of the capsule in which the latent heat storage material is enclosed. A fluid that evaporates at a temperature below the heat storage temperature of the latent heat storage material is used as the heat transfer fluid, and the fluid is filled so that the liquid level is below the heat transfer tube.

Function: Since the latent heat storage device of the present invention is constructed as described above,
Not only is safety ensured by exchanging heat through the heat transfer fluid without the fluid in direct contact with the latent heat storage material through the heat exchange wall, but the heat transfer fluid is also used in the latent heat storage material capsules. The liquid is heated by radiant heat from the tube or by heat transfer through contact, evaporates, rises, contacts the heat transfer tube, gives heat to the fluid inside, and becomes available for use as a heated liquid or vapor. . On the other hand, the heat medium fluid that has given heat to the fluid in the heat transfer tube is liquefied and falls downward in the heat storage tank, is heated again by the heat storage material capsule, and the above action is repeated.

In this case, the heat transfer fluid in contact with the heat transfer tube gives heat to the heat transfer tube and the internal fluid while transforming from a vapor state to a liquid, so the temperature at that time maintains the vaporization temperature of the fluid at that pressure. . In addition, since it becomes steam and comes into contact with the heat exchanger tube, it evenly and uniformly contacts the entire surface of the heat exchanger tube. Therefore, stable heat can be efficiently extracted during heat extraction.

Other objects of the present invention and structures for achieving them will be made clear by the detailed description of embodiments below with reference to the drawings.

Example FIG. 1 is a diagram showing an embodiment of the present invention.

Inside the heat storage tank 1, a large number of cylindrical capsules 2 filled with a latent heat storage material are installed in parallel in the vertical direction. Above the group of capsules in the internal space of the heat storage tank 1, there are provided heat transfer tubes 3 through which water to be heated and used as hot water or steam flows. In this embodiment, the heat transfer tubes 3 are formed in a two-stage spiral shape, each fixed to the lower surface of a shade-shaped member 4, and connected in series or parallel to a water supply pipe 5 and a hot water or steam extraction pipe 6. There is.

The outer surface of the heat storage tank is surrounded by a heat insulator 7. A heat medium fluid 8 is filled in the lower part of the space inside the heat storage tank. As the heat medium fluid 8, a fluid that evaporates below the heat storage temperature and does not become a solid layer even at the lowest temperature reached by the heat storage device is used, and it is also possible to use water.

In this embodiment, in which a safety valve 9 is provided at the top of the heat storage tank 1, the heat medium fluid 8, for example water, is filled to such an extent that its liquid level is below the lower end of the capsule 2.

Therefore, the heat transfer fluid 8 is heated by the radiant heat from the capsule 2 and rises in temperature, and when it reaches its boiling point, it evaporates into steam and rises through the gap in the capsule 2.

Contact the surface of capsule 2. As a result, it is heated and becomes superheated steam, which passes through the space between the capsules and comes into contact with the heat transfer tube 3, where it exchanges heat with the water inside.

In this example, since the heat transfer fluid contacts the heat transfer tube in the state of superheated steam, the temperature at all parts is definitely above the boiling point, and the temperature quickly reaches the predetermined boiling point through heat exchange.
Continuous heat exchange takes place at this temperature. The heat transfer fluid that has lost heat and liquefied moves to the surroundings along the lower surface of the umbrella 4, falls downward, vaporizes again, rises, and transfers heat.

Further, in this embodiment, since the heat medium fluid is not in contact with the capsule, there is an advantage that external heat radiation loss is reduced.

As shown in another embodiment shown in FIG. 2, when the heat transfer fluid 8 is filled to a level where part or all of the capsule 2 is immersed, the depth at which the capsule is immersed in the liquid is changed. By changing the amount of heat transferred from the capsule 2 to the heat transfer fluid 8, the amount of steam generated can be changed. can be adjusted so that it is in equilibrium with the amount of heat extraction.

In still another embodiment shown in FIG. 3, a liquid tank 10 is provided separately from the heat storage tank 1, and is communicated with the heat storage tank 1 through a communication pipe 11 at the lower part of each tank, so that the heat medium fluid 8 passes through the communication pipe 11 and is connected to both the heat storage tank 1 and the heat storage tank 1. It is possible to go back and forth between the tanks.

An air vent 12 is provided at the top of the liquid tank 10.

Therefore, when the heat transfer fluid 8 in the heat storage tank 1 is heated, the temperature rises, and the amount of steam increases, the steam pushes down the liquid level, and the liquid level, which was initially at the solid line, drops to the position shown by the broken line. , the liquid moves into the liquid tank 1o.

Therefore, the contact area of the liquid that contacts the capsule 2 is reduced, and the amount of liquid evaporated is reduced. The liquid level is maintained at a balance between the amount of evaporation and the amount of heat applied to the water in the heat transfer tube to turn it into a liquid, and heat exchange is performed in this state.

In addition, if a pump is interposed in the communication pipe 11 in this embodiment,
Since the liquid level in the heat storage tank can be arbitrarily adjusted, the liquid level of the heat medium fluid in the heat storage tank 1 can be adjusted according to the amount taken out from the takeout pipe 6 and the temperature of the hot water taken out.

Note that the liquid tank may be separated from the heat storage tank by a wall and provided integrally.

Effects As described above, according to the present invention, the fluid used exchanges heat via the latent heat storage material and the heat medium, so it is highly safe, and the temperature of the heat medium fluid in contact with the heat transfer tubes is maintained constant and uniform. The heat can be brought into contact with the heat exchanger and the stored heat can be extracted stably and with high heat exchange efficiency.

By setting the liquid level of the heat transfer fluid below the lower end of the capsule, a predetermined evaporation temperature can be reliably obtained.

By changing the liquid level of the heat transfer fluid, the amount of heat extracted and the amount of steam generated can be balanced. In addition, by providing a liquid tank in communication with the heat storage tank, the amount of steam generated can be automatically changed according to the amount of heat extracted, and by interposing a pump between the heat storage tank and the liquid tank, the amount of steam generated can be changed automatically according to the amount of heat extracted. You can change the amount of heat.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the invention, FIG. 2 is a sectional view showing another embodiment of the invention, and FIG. 3 is a sectional view showing still another embodiment of the invention. 1... Heat storage tank 2... Heat material capsule 3... Heat transfer tube 5... Water supply pipe 6... Hot water or steam extraction pipe 8... Heat medium fluid 10... Liquid tank (etc. 1 person) Figure

Claims (5)

[Claims] (1) A capsule enclosing a latent heat storage material and a heat transfer tube through which a fluid to be heated and used flows through are provided in a heat storage tank, and the heat stored in the latent heat storage material in the capsule is transferred to the fluid in the heat transfer tube. In a latent heat storage device in which a heat storage tank is filled with a heat transfer fluid that transfers to A latent heat storage device characterized in that it is a fluid that evaporates at a certain temperature and is filled so that its liquid level is below the heat transfer tube. (2) The latent heat storage device according to claim 1, wherein the heat transfer fluid is filled so that its liquid level is below the capsule. (3) The latent heat storage device according to claim 1, wherein the heat transfer fluid is filled so that part or all of the capsule is immersed therein. (4) The latent heat storage device according to claim 1, further comprising a liquid tank communicating with the heat storage tank at a lower part thereof and having an air vent. (5) The latent heat storage device according to claim 4, characterized in that a pump is interposed between the heat storage tank and the liquid tank.