JPH0381076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal energy storage device capable of storing thermal energy and extracting the stored thermal energy whenever required.

[Prior art]

In recent years, as energy resources have become tighter, studies have begun to consider heat cycle systems that utilize sunlight, which is an inexhaustible energy source, to store thermal energy during the day and release it at night. Thermal energy storage materials used for such purposes include the sensible heat type, which is represented by water and crushed stone, and the latent heat type, which uses phase change latent heat such as melting caused by inorganic salt hydrates and organic crystalline substances. exists. However, in the case of the former, the capacity and weight of the thermal energy storage device are considerably large, and the temperature of the thermal energy storage device itself decreases as heat is released, and furthermore, it may spontaneously release heat due to temperature changes in the environment in which it is placed. The problem is that it is released. On the other hand, the latter has the advantage that the device can be made more compact because of its large phase change latent heat, and the temperature drop of the thermal energy storage itself due to heat radiation is small. However, like the former sensible heat type, this latent heat type also has the problem of spontaneously releasing heat due to changes in the environmental temperature in which it is placed. Although these characteristics are useful in applications where the temperature is kept as constant as possible, such as in agricultural applications, they are useful in applications where the user is forced to release heat for the first time at any time and under any temperature conditions. is inconvenient. In other words, it cannot be used to release heat at a desired time, like the disposable body warmers that have become popular recently.
This is a factor that limits the usability of many latent heat type thermal energy stores.

However, recently, by adding xanthan gum to inorganic salt hydrate, it has become extremely stable in the state of storing thermal energy, and can be freely stored at any time and under any temperature conditions determined by the user. It was shown that energy could be released (Japanese Patent Application Laid-open No. 53578/1983). In other words, the publication states that thermal energy can be stored for a long period of time in a thermal energy storage material made of an inorganic salt hydrate such as sodium acetate trihydrate and xanthan gum, and that the stored thermal energy can be extracted using single crystal or sharp It has been disclosed that a nucleation source such as a material may be introduced from the outside or a weak current may be applied.

[Problem that the invention seeks to solve]

Therefore, the present inventors conducted a specific study on the technique disclosed in the above-mentioned publication, and found that each of the above-mentioned methods exhibits only extremely unstable reproducibility in extracting stored thermal energy. For example, when stimulating the surface of a thermal energy storage object with a sharp object, the surface of the thermal energy storage object to be stimulated must be almost free of moisture and become a hard film. In the case of a thermal energy storage product that is placed in a container, has a stable moisture balance, and does not have a hard film-like surface, nucleation will not occur even if stimulated with a sharp object.
It was therefore found that no release of thermal energy occurred. In other words, in a method that relies on stimulation with sharp objects, this means that the thermal energy storage device must always be used in some form of contact with the outside air to evaporate the moisture on the surface layer. When used for a long period of time, there is a problem that the initial performance deteriorates due to compositional changes due to water loss. There are also practical problems because it cannot be used in a closed container. On the other hand, current stimulation cannot reliably reproduce nucleation for unknown reasons. Compared to these methods, the method of throwing a single crystal into a thermal energy store certainly promotes nucleation and releases thermal energy, but
It is difficult to industrially connect and add a nucleation source such as a single crystal.

From this point of view, the present inventors have conducted intensive studies to determine whether it is possible to obtain a device that can be industrially connected to provide a nucleation source such as a single crystal to a thermal energy storage material, and have arrived at the present invention.

[Structure and outline of the invention]

That is, the present invention relates to a closed container filled with a thermal energy storage material made of a hydrophilic polysaccharide and an inorganic salt hydrate, and a closed container that is normally arranged so as not to come into contact with the thermal energy storage material, and which is arranged so as not to come into contact with the thermal energy storage material, and which is operated to start extracting the thermal energy. and a stimulator attached to the sealed container so as to be able to freely contact the energy storage, and the stimulator is filled with the thermal energy storage and the crystallization agent in contact with each other, and the stimulator is filled with the thermal energy storage and the crystallization agent in contact with The present invention relates to a thermal energy storage device characterized in that at least a portion of the energy store is exposed within the closed container so as to be in direct contact with the thermal energy store within the closed container.

Hydrophilic polysaccharide The hydrophilic polysaccharide, which is one of the components constituting the thermal energy storage product of the present invention, may be of any kind such as homopolysaccharides, heteropolysaccharides, or derivatives thereof. Examples of such hydrophilic polysaccharides include cellulose, which is a glucan, amylose,
Laminaran, amylopectin, glycogen, dextran from microorganisms, galactans such as agar agarose, λ-carrageenan, snail galactan, inulin from the rhizomes of dahlia and Jerusalem artichoke, levan, tritisin, etc., xylan from higher plants, elephant palm, seaweed, etc. Yeast mannan, N-acetylglucosamine polymer chitin, polygalacturonic acid pectic acid,
Homopolysaccharides such as arabinan from peanuts, apples, and sugar beets, or derivatives thereof, such as alkylation, acetylation, sulfate esterification, acetate esterification, etc., such as carboxymethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, dihydroxyethylcellulose, Examples include hydroxypropylcellulose. Alternatively, D-glucose and D
- Konjac mannan, a glucomannoglycan in which mannoses are bonded to each other β1→4, wood glucomannan, D- in the glucomannan main chain.
Galactoglucomannoglycan from coniferous wood in which galactose is branched with α1→6 bonds, guar gum (gualan), arabinogalactoglycan from larch, gum arabic, tragacanthic acid from gum tragacanth, alginic acid, glycosaminoglycan, locust vegan Heteropolysaccharides such as gum or their derivatives, as well as extracellular heteropolysaccharides, which are a type of heteropolysaccharide, i.e. bacteria Xanthomnas
D-glucose obtained from the medium of D. compestris,
A.
D-glucuronic acid obtained from the medium of D. indicum,
Acidic heteropolysaccharide whose constituent units are D-glycero-D-mannoheptose, D-glucose, and D-mannose, and D-glucose, D-mannose, and L
Examples include mixtures of neutral heteropolysaccharides having -arabinose and L-rhamnose as constituent units, and derivatives thereof. Among these, xanthan gum, hydroxyl alkyl cellulose such as hydroxyl ethyl cellulose, hydroxypropyl cellulose, etc. Hydroxyalkylated guar gum such as guar gum is preferred, and xanthan gum is particularly preferred since it has the best balance of these. Generally, xantham is available as “KELTROL” and “KELZAN” from Kekol.
Hydroxypropylated guar gum is commercially available under the trade name "Jager HP-11" and is readily available.

Xanthan gum is thought to have a repeating unit represented by the following general formula (), and most of its molecular weights are about 2 million to 5 million.

In the present invention, the above-mentioned hydrophilic polysaccharides can be used, but these may be used alone or in combination of two or more. Particularly suitable is a system in which xanthan gum, which has remarkable effects, is mixed with other polysaccharides as a main component. At this time, there is no particular restriction on the mixing ratio, and it is possible to mix at any desired ratio, but preferably the amount of xanthan gum is half or more. A feature of these mixtures is that they require less amount than when using xanthan gum alone, thus providing a highly efficient thermal energy store.

Inorganic Salt Hydrate Examples of inorganic salt hydrates include various types known as latent heat type heat storage agents. Specifically, lithium nitrate trihydrate (LiON ₃・3H ₂ O), sodium chromate decahydrate (Na ₂ CrO ₄・10H ₂ O),
Sodium sulfate decahydrate (Na ₂ So ₄・10H ₂ O), sodium carbonate decahydrate (Na ₂ CO ₃・10H ₂ O), sodium hydrogen phosphate decahydrate (Na ₂ HPO ₄・
12H ₂ O), sodium thiosulfate pentahydrate (Na ₂ S ₂ O _{3.5H 2} O), sodium acetate trihydrate (CH ₃ COONa.3H ₂ O), magnesium nitrate hexahydrate (Mg ( NO ₃ ) ₂・6H ₂ O), magnesium chloride hexahydrate (MgCl ₂・6H ₂ O), calcium chloride hexahydrate (CaCl ₂・6H ₂ O), strontium chloride hexahydrate (SrCl ₂・6H ₂ O), etc. These may be used alone or in combination of two or more.

Thermal Energy Store Thermal energy store is obtained by mixing the aforementioned hydrophilic polysaccharide and inorganic salt hydrate.
At this time, the type of hydrophilic polysaccharide is appropriately selected depending on the inorganic salt hydrate to be used so that the inorganic salt hydrate is sufficiently thickened to form a hydrogel and phase separation is prevented. Further, a third component may be added to both systems as necessary to stabilize the hydrogel state. Examples of such combinations include sodium acetate trihydrate-xanthan gum, sodium acetate trihydrate-hydroxypropyl guar gum, sodium acetate trihydrate-hydroxyethylcellulose, sodium acetate trihydrate-xanthan gum-
Locus bean gum, sodium sulfate decahydrate
Examples include xanthan gum and sodium chloride.

The mixing ratio of hydrophilic polysaccharide and inorganic salt hydrate varies depending on the type of polysaccharide used, the type of inorganic salt hydrate, or the type of combination thereof, so it is difficult to define it unconditionally. The sugar content is 1 to 10% by weight, preferably 2 to 5% by weight, and the inorganic salt hydrate is 90 to 99% by weight, preferably 95 to 98% by weight.

The thermal energy storage material with the above structure melts the inorganic salt hydrate by applying a heat source and stores energy, and even if the ambient temperature decreases and becomes below the melting point of the inorganic salt hydrate, it remains in the form of a hydrogel. Therefore, it has the characteristic that it continues to maintain supercooling and does not solidify (crystallize).

Crystallizing Agent Various known crystallizing agents can be used, such as strontium hydroxide, strontium halide, strontium carbonate, barium hydroxide, barium halide, barium carbonate,
Examples include barium thiosulfate, barium sulfate, nickel trichloride, talc, copper powder, borax, boric acid, and anhydrous inorganic salts. Among these, it is preferable to use an anhydride of the same inorganic salt as the inorganic salt hydrate constituting the thermal energy storage material.

The function of the crystallizing agent is to prevent supercooling of the inorganic salt hydrate in the thermal energy store. In other words, when a crystallizing agent is added, the inorganic salt hydrate in the molten state immediately solidifies when the temperature drops below the melting point, and even if a hydrophilic polysaccharide is present, it will not remain stable in a supercooled state in the form of a hydrogel. do not have.

Thermal Energy Storage Device The thermal energy storage device of the invention essentially consists of a closed container filled with a thermal energy store and a stimulating body. The stimulator is filled with a thermal energy store and a crystallizing agent in contact with each other, with at least a portion of the thermal energy store being exposed within the closed container. This stimulator is placed so that it does not come into contact with the thermal energy storage in a normal closed container, and by the operation of starting thermal energy extraction,
It is attached to the closed container so that its exposed portion can freely contact the thermal energy store within the closed container. By adopting such a configuration, the thermal energy stored in the closed container, which is in the form of a hydrogel in a molten state due to supercooling, is
The thermal energy stores in the stimulus body, which have already solidified by the action of the crystallizing agent, can be brought into contact at any time. Then, the solidification of the thermal energy storage in the sealed container propagates through the contact portion of the thermal energy storage of the solidified stimulus, and the stored thermal energy is released. The contact time of this stimulator does not need to be long and may be instantaneous.

〔Example〕

An example of the thermal energy storage device of the present invention will be explained using FIG. 1. The closed container 1 is filled with thermal energy storage 6 . A tubular stimulator 3 is connected to a spring 5 through a gasket 2 at the top of the container.
It is provided with. The opening of the tubular stimulator on the side that comes into contact with the thermal energy storage in the closed container is filled with thermal energy storage 6, and the other space is filled with crystallization agent 7. The stimulator 3 is normally arranged so as not to come into contact with the thermal energy storage 6 in the container 1, and the thermal energy storage 6 of the stimulator 3 is transferred to the thermal energy storage 6 in the closed container 1 by the thermal energy extraction starting operation. It is attached so that it makes contact with the A stopper 4 is attached to the other opening of the stimulator to prevent evaporation or compositional changes of the crystallizing agent and thermal energy stores within the stimulator. When the stimulator is brought into contact with the thermal energy storage in the sealed container, the stimulator may be pushed down by some mechanical action to initiate thermal energy extraction, and the thermal energy stored in the stimulator is brought into contact with the thermal energy stored in the sealed container. Once in contact, the stimulator returns to its original position due to the mechanical action of the spring 5. At this time, the upper space inside the closed container may be filled with water or the like.

The nucleating agent for crystallizing the thermal energy storage material 6 in the closed container 1 is preferably a crystallized substance of the same type as the thermal energy storage material 6;
It is difficult to maintain only a portion of the thermal energy store 6 in the closed container 1 in a crystallized state. However, in the above-mentioned thermal energy storage device, since a part of the thermal energy storage material 6 in the stimulation body 3 is filled with the increase in volume that has come into contact with the crystallization agent 7, the thermal energy storage material 6 in the stimulation body 3 is kept at a low temperature. At the bottom, it crystallizes and solidifies without being supercooled. Therefore, when the stimulator 3 is pushed down in this state, the crystallized thermal energy storage material 6 comes into contact with the thermal energy storage material 6 that has become hydrogel-like due to supercooling in the container 1, becomes a nucleus, and the crystallization occurs. promote. In this case, even if the different types of crystallizing agents 7 come into direct contact with the thermal energy storage material 6, the crystallization rate is slow and long-term contact is required; however, if the crystallized products of the same type of thermal energy storage material 6 come into contact , crystallization occurs over time, and thermal energy is released instantaneously.

〔Effect of the invention〕

As described above, the device of the present invention can extract thermal energy at any desired time, can be used repeatedly, and because the thermal energy stored in the device is in a sealed environment, It exhibits stable properties over a long period of time without any change.

Utilizing these properties, the device of the present invention can be used as an instant warmer for leisure or survival such as fishing or diving, a room heater for home use,
It can be used as a winter preheater for bicycle engines, and as a decoy for heat-sensitive missiles.

[Brief explanation of drawings]

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

Claims (1)

[Scope of Claims] 1. A closed container filled with a thermal energy storage material made of a hydrophilic polysaccharide and an inorganic salt hydrate, and an operation for starting the extraction of thermal energy, which is normally arranged so as not to come into contact with the thermal energy storage material. a stimulator attached to the closed container so as to be able to freely contact the thermal energy storage, the stimulator is filled with the thermal energy storage and a crystallizing agent in contact with each other, and at least a portion of the thermal energy storage is exposed within the closed container so as to be in direct contact with the thermal energy storage within the closed container. 2. The thermal energy storage device according to claim 1, wherein the hydrophilic polysaccharide constituting the thermal energy storage material is selected from hydroxyalkylcellulose, hydroxyalkylated guar gum, and xanthan gum. 3 The inorganic salt hydrate constituting the thermal energy storage material is sodium acetate trihydrate or sodium sulfate 10
The thermal energy storage device according to claim 1 or 2, which is a hydrate.