JPS648260B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in heat storage devices used in air conditioners that utilize solar heat.

Conventionally, when storing heat in a relatively low temperature range such as in air conditioning or heating, the sensible heat of water, etc. has been used, but recently methods have been developed that utilize the heat of fusion of inorganic salts or organic salts, especially their hydrated salts. is being attempted.

However, when an inorganic salt or an organic salt is used as a heat storage material, it has the advantage of having a high heat storage density and being able to dissipate heat at a predetermined temperature. The disadvantage is that it does not solidify and does not dissipate heat efficiently.

Measures to prevent such overcooling include adding nucleation aids and equipping the heat storage device with an accessory device that provides a mechanical shock, but the effects are not always sufficient.

Therefore, the present inventor conducted intensive research to find a means to minimize supercooling of heat storage materials based on inorganic salts or organic salts, and efficiently carry out the heat storage-heat release cycle. Alternatively, the inventors have found that this object can be easily achieved by using a heat storage device containing an organic salt and having at least one pair of electrodes, and have filed a patent application.

This device is designed so that a voltage can be applied between the electrodes, thereby preventing overcooling of the heat storage material, and crystallization or solidification of the molten liquid begins at a desired temperature, allowing for efficient heat dissipation. be.

However, upon further investigation by the present inventor, it was found that repeated application of voltage over a long period of time tends to cause a decrease in heat generation efficiency due to performance deterioration of the heat storage material or wear of the electrodes, and it was found that there is room for further improvement. did.

However, the inventor of the present invention believes that the cause of this problem is that part of the heat storage material undergoes side reactions such as electrolysis on the electrode surface when voltage is applied, and the above problem can be solved by protecting the electrode surface in some way. As we continued our research to solve this problem, we discovered that if the surface of the electrode is coated with a hydrophilic polymer, it is possible to minimize the deterioration of the heat storage material and the wear and tear of the electrode without causing any problems in preventing supercooling. The present invention was completed after discovering the remarkable effect that it is possible.

That is, the present invention is a heat storage device comprising an arbitrarily shaped container containing an inorganic salt or an organic salt, and at least a pair of electrodes whose surfaces are coated with a hydrophilic polymer. explain.

First, the container in the present invention is not limited to its material or shape, and may be of any type, as long as it can contain an inorganic salt or an organic salt. Examples of the material include plastic, metal, carbon material, glass, concrete, and brick. As shown in Figures 1 to 6, the shapes are cubic, rectangular,
Any type may be used, such as a spherical type, a pipe type, a sausage type, and a panel type. However, the present invention is not limited to only these shapes.

It is essential that the device be designed to have at least one pair of electrodes and to be able to apply a voltage between them. By incorporating this device, overcooling of the heat storage material can be prevented, crystallization or solidification of the molten liquid begins at a desired temperature, and efficient heat dissipation can be realized.

It is sufficient that at least one pair of electrodes be provided. It may be located anywhere on the container, and the container itself may form one or both electrodes. However, in any case, the heat storage material and the electrode must be kept in contact.

Although the material of the electrode is not specified, it is preferably one with a large hydrogen overvoltage. Amorphous carbon, artificial graphite, copper silicide, lead, lead-antimony alloy, lead-silver alloy, iron, iron-silicon alloy, fused magnetite, platinum, silver, aluminum, copper, zinc, antimony, tin, mercury, various amalgams, chromium, Examples include cadmium. Especially copper amalgam, copper alloys (e.g. copper and iron,
At least one alloy of zinc, tin, nickel, manganese, chromium, aluminum, molybdenum, antimony, etc.) amalgam is effectively used.

The shape of the pair of electrodes may be the same or different. Further, the electrode materials may be a combination of different types of electrodes.

The surface of the electrode must be coated with a hydrophilic polymer. The coating method is not particularly limited, and may include a method in which the electrode is immersed in a hydrophilic polymer solution, dried, and if necessary, subjected to appropriate heat treatment to form a coating layer on the electrode surface. Any method can be used, such as a spraying method, a method of bringing a hydrophilic polymer film or fibrous material into close contact with the electrode surface, etc. Further, the hydrophilic polymer may form the coating layer in any desired state such as gel or foam.

The hydrophilic polymer used in the present invention is a polymer containing a hydrophilic group such as a hydroxyl group, a carboxyl group, or an amide group in its molecule, and specifically includes the following.

Partially saponified or completely saponified polyvinyl alcohol, polyvinyl alcohol formalized products, acetalized products, butyralized products, urethanized products, acetoacetate esterified products, esterified products with sulfonic acids, carboxylic acids, etc. Furthermore, saponified copolymers of vinyl esters and monomers copolymerizable therewith may be mentioned, and the monomers include ethylene,
Propylene, isobutylene, α-octene, α-
Olefins such as dodecene and α-octadecene,
Unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, their salts or mono- or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide and methacrylamide Examples include olefin sulfonic acids or their salts such as ethylene sulfonic acid, allyl sulfonic acid, and meta-allylsulfonic acid, alkyl vinyl ethers, vinyl ketones, N-vinyl pyrrolidone, vinyl chloride, and vinylidene chloride. However, it is not necessarily limited to this.

Hydrophilic polymers other than polyvinyl alcohols include methyl cellulose, ethyl cellulose,
Cellulose derivatives such as hydroxymethylcellulose, hydroxypropylmethylcellulose, hydroxybutylmethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, aminomethylhydroxypropylcellulose, aminoethylhydroxypropylcellulose, starch, tragacanth, pectin, glue, alginic acid or its salts, gelatin, polyvinyl Pyrrolidone, polyacrylic acid or its salts, polymethacrylic acid or its salts, polyacrylamide, polymethacrylamide, vinyl acetate and maleic acid, maleic anhydride, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, etc. Examples include copolymers with saturated acids, copolymers of styrene and the above-mentioned unsaturated acids, copolymers of vinyl ether and the above-mentioned unsaturated acids, and salts or esters of the above-mentioned copolymers.

The hydrophilic polymer may be post-treated or mixed with any compound such as a water-resistant agent, a crosslinking agent, a gelling agent, a thickener, a plasticizer, a film-forming aid, etc., without any problem.

A voltage is applied to prevent overcooling, and the appropriate voltage is 1 μV to 10V, preferably 0.2 to 3V.
The voltage application time is about 1 ns to 100 seconds. The type of power source may be direct current, alternating current (low frequency, high frequency), or pulse. The timing of voltage application is most effective when a supercooled state is recognized.

Next, the inorganic salt or organic salt to be stored in the container as a heat storage material varies somewhat depending on the intended temperature range, but for example, as a heat storage material for 30 to 60°C, calcium chloride hexahydrate, Sodium sulfate decahydrate, sodium carbonate decahydrate, hydrogen phosphate 2
Sodium dodecahydrate, calcium nitrate tetrahydrate, sodium thiosulfate pentahydrate, sodium acetate trihydrate, etc. are used as heat storage materials for temperatures between 80 and 120°C, such as magnesium nitrate hexahydrate, potassium alum (decahydrate), etc. ), ammonium alum (12 hydrate), magnesium chloride hexahydrate,
Examples include potassium nitrate/lithium nitrate, potassium nitrate/lithium nitrate/sodium nitrate, and the like.

One or more of the above-mentioned heat storage devices are used as a heat storage tank by combining them in series and/or in parallel.

FIG. 7 shows one example of the simplest model heat storage device (of course, the present invention is not limited to such an example), and 1 is a heat storage device of the present invention with an inorganic or organic salt inside. is filled and stored. 2 is an electrode, 3 is a power source, 4 is a power switch, 5 is a heat exchanger made of a coiled copper pipe, P is a pump, 6
numeral 8 is a water tank filled with water, which is circulated between the heat exchanger, the water tank, and the radiator 7 by means of a pump; and 8 is a switch for switching the circulating water.

First, during the day, the water heated by the sun's heat in 6 is sent into 1 through a pipe. The heat storage material in 1 is melted by the heat exchanger 5 and heat is stored. The heat-exchanged water is circulated to 6, and after heating is introduced into 1 again. At night, switch the Kotoku 8 so that the circulating water flows to the radiator. The heat storage material in 1 begins to radiate heat, and the circulating water is heated by the heat exchanger 5, which enters the radiator and is used for heating. When heat dissipation progresses and supercooling is recognized and no solidification heat is generated, switch 4 is closed and a voltage is applied between electrodes 2. Then, after a few seconds, the supercooling is destroyed and solidification begins.
The generation of heat of solidification continues to heat the circulating water.

The heat storage device described above can be made more practical by being equipped with optional accessory devices such as a temperature detection device to check the temperature of the heat storage material and a voltage control device to adjust the voltage. I can do it.

Hereinafter, the present invention will be explained in more detail by giving examples.

Example 1 A copper amalgam electrode (rod-shaped body with a diameter of 2 mm and a length of 10 cm) was immersed in a 20% by weight aqueous solution of polyvinyl alcohol with a degree of polymerization of 2000 and an average degree of saponification of 99 mol%.
Polyvinyl alcohol was attached to the surface. Subsequently, the electrode was air-dried to obtain an electrode coated with polyvinyl alcohol.

A large test tube with an inner diameter of 5 cm was filled with sodium acetate trihydrate, and a small amount of liquid paraffin was added as a water evaporation inhibitor. A pair of the copper amalgam electrodes were inserted from the top of the test tube so as to make contact with the filling.

After heating to 80℃ and melting sodium acetate trihydrate, it was allowed to cool. When the internal temperature dropped to 50℃, voltage (2.4V, 60Hz AC) was applied to the electrode, and after 2 to 3 minutes. Crystals of sodium acetate trihydrate precipitated and solidification began, and the internal temperature rose to 58°C.

Thereafter, heat cycles between 48°C and 75°C were repeated over 300 times, but no deterioration in the quality of sodium acetate trihydrate (coloration, decrease in calorific value) or deterioration of the amalgam electrode was observed.

Note that when the same experiment as above was repeated using an electrode not coated with polyvinyl alcohol, the sodium acetate trihydrate started to be colored slightly brown.

Example 2 The same experiment as in Example 1 was conducted, except that the electrodes were replaced with zinc-copper amalgam pairs, and the same results were obtained.

Example 3 In Example 1, when a rectangular wave voltage of 3V and 0.1 Hz was applied, crystals began to precipitate after 3 minutes.

Examples 4 to 6 A 14% aqueous solution of polyvinyl alcohol with a degree of polymerization of 1800 and an average saponification degree of 88 mol% (Example 4), a 14% aqueous solution of polyvinyl alcohol modified with monomethyl maleate (amount of modification 2 mol%, an average saponification degree of 99 mol%) 16% by weight aqueous solution (Example 5), sodium allylsulfonate modified polyvinyl alcohol (denaturation amount 1.5% by mole,
An experiment was carried out according to Example 1, except that the electrode was coated with a 20% by weight aqueous solution (Example 6) with an average degree of saponification of 90 mol%. When 1V alternating current was applied, crystals of sodium acetate trihydrate began to precipitate one minute later.

No deterioration of the electrode or sodium acetate trihydrate was observed even after the heat cycle was repeated over 300 times.

Example 7 When the same method as Example 1 was carried out except that the electrode was coated with a 3% by weight aqueous solution of carboxymethylcellulose, crystal precipitation occurred 3 minutes after voltage was applied, and deterioration was also observed. I couldn't help it.

Example 8 When the same method as Example 1 was carried out except that the electrode was coated with a 2% aqueous solution of acrylamide/acrylic acid copolymer, crystals began to precipitate 7 minutes after voltage was applied. . No deterioration was observed even after repeated heat cycles.

[Brief explanation of drawings]

1 to 6 show one example of the heat storage device of the present invention. The upper and lower protrusions of each container are a pair of electrodes. FIG. 7 is a schematic diagram for explaining heating and cooling using the heat storage device of the present invention.

Claims (1)

[Scope of Claims] 1. A heat storage device comprising an arbitrarily shaped container containing an inorganic salt or an organic salt and comprising at least a pair of electrodes whose surfaces are coated with a hydrophilic polymer. 2. The heat storage device according to claim 1, wherein the organic salt is sodium acetate trihydrate.