JP2001064635A - Latent heat storage material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a latent heat storage material enabling its melting temperature to simply and conveniently be controlled by using a specific manganese nitrate hydrate. SOLUTION: This latent heat storage material composition comprises a manganese nitrate hydrate having a composition represented by the general formula Mn(NO3)2.nH2O ((n) is 3 to 7) as a principal ingredient and the melting temperature of the latent heat storage material composition is preferably controlled by adding 0.1-30 pts.wt. of a metal chloride (e.g. lithium chloride).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a latent heat storage material. More specifically, the present invention relates to a latent heat storage material composition excellent in energy efficiency at 0 to 35 ° C., which is suitable for a system for cooling and heating air conditioning of houses, buildings, greenhouses and the like.

[0002]

2. Description of the Related Art By raising and lowering the temperature, melting and solidification occur, and a substance that absorbs and releases a large amount of latent heat at a constant temperature can accumulate this latent heat without a temperature change. Since this can be used more effectively by releasing or absorbing heat when needed, it has been studied for a long time as a latent heat storage material that is useful for cooling and heating by using solar heat, waste heat or midnight power as a latent heat storage material. ,It's being used.
As such materials, organic substances such as polyethylene glycol, high-density polyethylene and wax, and inorganic substances such as calcium chloride hexahydrate and sodium sulfate decahydrate have been proposed.

[0003]

The inorganic hydrate salt has advantages such as a large latent heat of fusion and excellent resource properties. However, when dissolved, it separates into two phases, a solid inorganic salt and a saturated aqueous solution thereof. However, a hydrated salt may not be formed even when the mixture is cooled (phase separation), or a phenomenon may occur in which the material is cooled and does not solidify and does not radiate heat even after the solidification point has passed (supercooling). Further, in order to use the latent heat storage material, there is a disadvantage that it is necessary to adjust the melting temperature to fall within a use temperature range (effective heat storage temperature range).

[0004] Among them, controlling the melting temperature is of the utmost importance. For example, calcium chloride hexahydrate has a freezing point of 29 ° C. and a latent heat of 41 cal / g. As a method for controlling the freezing temperature, Japanese Patent Application Laid-Open No. Hei 10-237433 discloses that a polyhydric alcohol is used for 100 parts by weight of calcium chloride hydrate. A method of mixing 10 to 35 parts by weight with 0.1 to 20 parts by weight of strontium chloride and / or barium chloride has been proposed.

Also, sodium sulfate decahydrate has a freezing point of 3
The temperature is 2.5 ° C. and the latent heat is about 60 cal / g.
Compositions comprising 70-90% by weight of sodium sulfate decahydrate, 3-17% by weight of ammonium chloride, 1-13% by weight of sodium chloride and 1-13% by weight of ammonium sulfate have been proposed. In these methods, several kinds of additives are used for an inorganic salt as a main component. Generally, it has been pointed out that the use of such additives has a disadvantage such as an increase in cost. That is, an object of the present invention is to provide a novel latent heat storage material composition in which the solidification temperature can be easily controlled and the amount of latent heat is small.

[0006]

Means for Solving the Problems As a result of various studies to solve the above problems, the present inventors have found that a latent heat storage material composition mainly composed of manganese nitrate hydrate is used, and that an additive is used. As a result, it has been found that the melting temperature can be easily controlled, and the present invention has been completed.

[0007]

That is, the present invention provides a compound of the general formula Mn (NO ₃ ) ₂ .nH ₂ O (where n is 3 to 7).
Is a latent heat storage material composition mainly composed of manganese nitrate hydrate having the following composition. In addition, the general formula Mn (NO ₃ ) ₂
A latent heat storage material mainly composed of manganese nitrate hydrate having a composition of nH ₂ O (where n is 3 to 7);
A latent heat storage material composition characterized in that 0.1 to 30 parts of a metal chloride is added to control the melting temperature.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The manganese nitrate hydrate used in the present invention has a general formula of Mn (NO ₃ ) ₂ .nH ₂ O
(Where n is 3 to 7). In the case of manganese nitrate hexahydrate, the latent heat of fusion is about 130 J / g, which is sufficient for use as a latent heat storage material. Conventionally, various inorganic substances have been studied as latent heat storage materials, but manganese nitrate hydrate has not been studied, which is a completely new application example.

As manganese nitrate hydrate, hexahydrate and tetrahydrate are known, but water of crystallization changes continuously. Therefore, for example, by adding water to a commercially available manganese nitrate hexahydrate, or by dehydrating using a known method such as vacuum drying, the amount of water of crystallization of the hydrated manganese nitrate used in the present invention is adjusted. . At this time, the crystallization water is preferably a trihydrate to a heptahydrate.
If it exceeds this range, the coagulability deteriorates. The manganese nitrate hydrate thus prepared has a solidification temperature of about 32 ° C. for tetrahydrate and about 25 ° C. for hexahydrate.

However, when used for indoor air-conditioning management, the temperature is 25 ° C. or less, and in the case of a greenhouse during winter, the temperature ranges from several ° C. to 0 ° C.
A melting temperature of ° C. may be required. At this time, in the present invention, the melting temperature can be freely controlled by adding 0.1 to 30 parts by weight of a metal chloride in the latent heat storage material mainly containing manganese nitrate hydrate. .

The chlorides usable herein include lithium chloride, sodium chloride, rubidium chloride, cesium chloride, magnesium chloride, calcium chloride, calcium chloride tetrahydrate, calcium chloride dihydrate, strontium chloride, and strontium chloride hexahydrate. Hydrate, barium chloride, barium chloride dihydrate, lanthanum chloride heptahydrate, cerium chloride heptahydrate, samarium chloride hexahydrate, titanium tetrachloride, titanium trichloride, zirconium chloride, niobium chloride, tantalum chloride , Chromium chloride hexahydrate, molybdenum chloride, tungsten chloride, manganese chloride tetrahydrate, iron chloride (I
I) anhydrous, iron (III) chloride anhydrous, iron (II) chloride tetrahydrate, iron (III) hexahydrate, anhydrous cobalt chloride,
Cobalt chloride hexahydrate, anhydrous nickel chloride, nickel chloride hexahydrate, copper (I) chloride, copper (II) chloride anhydrous, copper (II) chloride dihydrate, silver chloride, chloroauric acid trihydrate , Gold (III) chloride tetrahydrate, chloroauric acid tetrahydrate, zinc chloride,
Cadmium chloride (anhydrous) Cadmium chloride hemihydrate,
Mercury (I) chloride, mercury (II) chloride, aluminum chloride, aluminum chloride hexahydrate, indium chloride tetrahydrate, thallium chloride, silicon tetrachloride, germanium chloride, tin (II) chloride anhydrous, tin (II) chloride ) Dihydrate, tin (IV) chloride anhydrous, tin (IV) chloride pentahydrate, lead chloride, antimony (III) chloride, antimony (V) chloride, bismuth chloride, tellurium chloride, tellurium (I)
V) is exemplified.

Among them, alkali metal and alkaline earth metal chlorides (for example, lithium chloride, sodium chloride, rubidium chloride, cesium chloride, and the like) which have good solubility in liquid manganese nitrate hydrate and are inexpensive. Magnesium chloride, calcium chloride, calcium chloride tetrahydrate, calcium chloride dihydrate, strontium chloride, strontium chloride hexahydrate, barium chloride, barium chloride dihydrate) are awarded.

Looking at the relationship between the amount of addition and the melting temperature, there is a positive correlation between the number of moles of the additive and the decrease in the melting temperature. The phenomenon involved is that when glycols are added to water, the freezing point is lowered and used as an antifreeze, etc., there is a molar freezing point drop, but by adding a small amount of chloride to manganese nitrate hydrate, There is a point that the phenomenon of lowering the melting temperature is hardly referred to as lowering of the molar freezing point. Molar freezing point depression is a phenomenon that occurs in dilute solutions, and there is an assumption that there is no interaction between solutes.

However, the liquid manganese nitrate hydrate is not a molten salt but a concentrated aqueous solution, which is contrary to the above assumption. The concept of adding a metal chloride to this manganese nitrate hydrate to control the melting temperature and applying it to a latent heat storage material is novel and revolutionary. In the case of the present invention, the amount of the additive is 0.1 to 30 parts by weight. If the content is less than 0.1 parts by weight, the melting temperature decreases by 1 ° C.
When the amount exceeds 30 parts by weight, the melting temperature decreases, but the ratio of the temperature decrease to the added amount becomes asymptotic, and the latent heat of fusion decreases, which is disadvantageous.

[0015]

The present invention will be specifically described below with reference to examples. Note that the present invention is not limited to these examples.

Example 1 A commercially available manganese nitrate hexahydrate was heated to about 40 ° C. and completely melted. This liquid manganese nitrate hydrate was stirred, and a part thereof was taken and sealed in a sealed container for DSC. Here, the process from melting to encapsulation of the sample was performed in a nitrogen stream, so that moisture in the air was not absorbed by the sample. This sealed container was set in a DSC (DCS6100, manufactured by Seiko Instruments Inc.), the sample was heated to 50 ° C., and held for 10 minutes. Then -20
Temperature to 3 ° C / min using liquid nitrogen to -20 ° C
For 10 minutes. Thereafter, the sample was heated to 50 ° C. at 3 ° C./min, and the melting temperature and the latent heat of fusion were measured.
As a result, the melting temperature was 25.0 ° C. and the latent heat of fusion was 129.
It was 8 J / g.

[0016]

Example 2 A commercially available manganese nitrate hexahydrate was heated to about 40 ° C., 9.9 g was precisely weighed and dispensed into a 50 ml sample bottle. To this was precisely added 0.1 g of the metal chlorides listed in Table 1. This sample bottle was set in an ultrasonic cleaner using kerosene and mixed well. Thereafter, the mixture was sealed in a sealed container for DSC. Here, the process from melting to encapsulation of the sample was performed in a nitrogen stream, so that moisture in the air was not absorbed by the sample. Hereinafter, the melting temperature and the latent heat of fusion were measured in the same procedure as in Example 1.

[0017]

[0018]

Example 3 A commercially available manganese nitrate hexahydrate was heated to about 40 ° C., 7.5 g was precisely weighed and dispensed into a 50 ml sample bottle. To this was precisely added 2.5 g of sodium chloride. When the melting temperature and the latent heat of fusion were measured in the same procedure as in Example 2, the melting temperature was 3.1 ° C. and the latent heat of fusion was 6
1.1 J / g.

[0019]

Comparative Example 1 Commercially available manganese nitrate hexahydrate was heated to about 40 ° C., and 5.0 g was precisely weighed and dispensed into a 50 ml sample bottle. To this was precisely added 5.0 g of sodium chloride. When the melting temperature and the latent heat of fusion were measured in the same manner as in Example 2, the melting temperature was −5.5 ° C. and the latent heat of fusion was 8.1 J / g.

[0020]

COMPARATIVE EXAMPLE 2 A commercially available manganese nitrate hexahydrate was heated to about 40 ° C., sodium nitrate was added thereto, and the mixture at the ratio shown in Table 2 was adjusted to a 50 ml sample bottle. Hereinafter, the melting temperature and the latent heat of fusion were measured in the same procedure as in Example 2. The results are shown in Table 2.

[0021]

[0022]

According to the present invention, a novel latent heat storage material, manganese nitrate hydrate, has been found. Further, by adding a metal chloride to this manganese nitrate hydrate, the melting temperature can be freely controlled. This amount of latent heat storage material is suitable for an air conditioning cooling and heating system.

Continuing on the front page (72) Inventor Hiroyoshi Horikawa 11-chome, Kita-ku, Sapporo City 11-Chome, Hokkaido Industrial Testing Laboratory (72) Inventor Keiichi Katsuyo 11-chome, Kita-ku, Sapporo City On-site (72) Inventor Kohei Iwata 8-Hokkaido Kita-ku, Kita-ku, Sapporo City Inside Hokkaido University

Claims (2)

[Claims] 1. A latent heat storage material composition mainly composed of manganese nitrate hydrate having a composition of the general formula Mn (NO ₃ ) ₂ .nH ₂ O (where n is 3 to 7). 2. A latent heat storage material mainly composed of manganese nitrate hydrate having a composition of the general formula Mn (NO ₃ ) ₂ .nH ₂ O (where n is 3 to 7). A latent heat storage material composition characterized by adding a part of metal chloride to control the melting temperature.