JPH0135278B2 - - 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 radiate heat at a predetermined temperature. It has the disadvantage 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 found that if the surface of the electrode was coated with a hydrophobic polymer, it would be 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 that stores an inorganic salt or an organic salt in a container of any shape and is equipped with at least a pair of electrodes whose surfaces are coated with a hydrophobic 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 vipe 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 a voltage applied 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. In particular, copper amalgam and copper alloy (for example, an alloy of copper and at least one of iron, zinc, tin, nickel, manganese, chromium, aluminum, molybdenum, antimony, etc.) amalgam are 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 hydrophobic polymer. The method of coating is not particularly limited, and the method includes immersing the electrode in a hydrophobic polymer solution, drying it, and subjecting it to appropriate heat treatment if necessary to form a coating layer on the electrode surface, or applying a hydrophobic polymer solution to the electrode surface. Any method can be used, such as a method of spraying, a method of bringing a hydrophobic polymer film or fibrous material into close contact with the electrode surface, etc. The effect is somewhat influenced by the thickness of the hydrophobic polymer, so it is usually less than 1000μ, preferably 1μ to 100μ, particularly preferably 10μ to
A film thickness of 30μ is advantageous. Further, the hydrophobic polymer may form the coating layer in any desired state, such as a gel state or a foam state. Hydrophobic polymers used in the present invention include olefin polymers or copolymers such as polyethylene and polypropylene, styrene polymers or copolymers, vinyl acetate polymers or copolymers, acrylic ester polymers, or Copolymers, methacrylic acid ester polymers or copolymers, vinyl chloride polymers or copolymers, vinylidene chloride polymers or copolymers, acrylonitrile polymers or copolymers, methacrylonitrile polymers or copolymers, vinyl ether polymers or copolymers, other poly-
P-xylylene, fluorine plastic, polycarbonate, polyester, polyamide, diene plastic, urethane plastic, urea resin, melamine resin, phenolic resin, furan resin, alkyd resin, unsaturated polyester resin,
Examples include epoxy resin. The hydrophobic polymer includes a crosslinking agent, a gelling agent, a thickening agent,
It may be post-treated or mixed with any compound such as a plasticizer or a film-forming aid. 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
is a water tank filled with water, which is circulated between the heat exchanger, the water tank, and the radiator 7 by a pump. Also, 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 salt 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 10% toluene solution of methyl methacrylate/n-butyl methacrylate copolymer (composition ratio 6/4), and the copolymer was applied to the surface of the electrode. The composite was adhered and dried to obtain a hydrophobic polymer coated electrode with a film thickness of 6.4 μm. 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℃ to melt sodium acetate trihydrate, it was allowed to cool. When the internal temperature fell to 50℃, voltage (2.4V, 60Hz AC) was applied to the electrode, and after 7 seconds, sodium acetate was dissolved. Trihydrate crystals precipitated and solidification began, and the internal temperature rose to 58°C. Thereafter, heat cycles from 45°C to 80°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 a hydrophobic polymer, the sodium acetate trihydrate began to be colored slightly brown. Examples 2 to 9 Experiments were conducted according to Example 1 using electrodes as shown in Table 1. The results are shown in Table 1.

[Table] Example 10 A copper amalgam electrode (rod-shaped body with a diameter of 2 mm and a length of 10 cm) is immersed in a 10% triene solution of methyl methacrylate/n-butyl methacrylate copolymer (composition ratio 6/4), and the surface is The copolymer was deposited and dried to obtain a hydrophobic polymer coated electrode with a film thickness of 10 μm. A large test tube with an inner diameter of 5 cm was filled with calcium chloride hexahydrate, 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 and melting calcium chloride hexahydrate, it was allowed to cool, and when the internal temperature fell to 23℃, a voltage (1.1V, 100 Hz alternating current) was applied to the electrode.
After 21 seconds, crystals of calcium chloride hexahydrate precipitated and solidification began, and the internal temperature rose to 29°C. Thereafter, heat cycles from 20°C to 50°C were repeated over 300 times, but no deterioration in the quality of the calcium chloride hexahydrate (coloring, 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 a hydrophobic polymer, calcium chloride hexahydrate began to be colored slightly blue. Examples 11 to 18 Experiments were conducted according to Example 10 using electrodes as shown in Table 2. The results are shown in Table 2.

【table】 [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 hydrophobic polymer. 2. The heat storage device according to claim 1, wherein the organic salt is sodium acetate trihydrate. 3. The heat storage device according to claim 1, wherein the hydrophobic polymer has a film thickness of 1000 μm or less.