JP3471469B2 - Latent heat storage material composition - Google Patents

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 composition, and more particularly to a cooling system for air conditioning useful for storing heat in a low temperature (5 to 10 ° C) range suitable for a heating and cooling system for air conditioning of houses and buildings. The present invention relates to a latent heat storage material composition for a system.

[0002]

2. Description of the Related Art As a heat storage material for cooling suitable for an air conditioning system, it is practically useful to use latent heat of fusion in a temperature range of 0 ° C to 10 ° C. Paraffin compounds such as tetradecane (melting point 5 ° C.) and pentadecane (melting point 9.9 ° C.) are known as the main ingredients of the heat storage material, but these are flammable substances from the standpoint of the Fire Defense Law. Currently, it is rarely used.

On the other hand, it is also known to use an inorganic compound as a main component of a heat storage material. For example, a binary system composition of disodium hydrogen phosphate dodecahydrate and dipotassium hydrogen phosphate hexahydrate. The material (melting point: 5 ° C.) has a serious problem in practical use because the supercooling has not been completely solved. In addition, a binary composition (melting point 8 to 12 ° C.) of lithium nitrate trihydrate having magnesium nitrate trihydrate as a main component and magnesium chloride hexahydrate and lithium nitrate trihydrate-chloride Magnesium hexahydrate-magnesium bromide hexahydrate ternary composition (melting point 5.8 to 9.7 ° C) and the like correspond to Category 1 of dangerous substances according to the Fire Service Act, and storage method, It has not been put to practical use, leaving problems such as storage capacity.

However, sodium sulfate decahydrate or its eutectic has a large latent heat of fusion and a melting point of 30.
Since it is around ℃ and has excellent resource properties,
It has been known for a long time as a useful latent heat storage material for cooling and heating by utilizing solar heat, exhaust heat, or using midnight power, and has been studied for a long time.

As a heat storage material for cooling suitable for an air conditioning cooling / heating system, in order to utilize the latent heat of fusion in the temperature range of 0 ° C. to 10 ° C., a eutectic substance is formed by another salt or a freezing point depressant is added. A method has been proposed. Known freezing point depressants include, for example, sodium chloride, ammonium chloride, ammonium bromide, potassium chloride and the like. Further, in Japanese Patent Application Laid-Open No. 2-92988, various inorganic salts are added to sodium sulfate decahydrate and the thermal behavior thereof is examined, and it is stated that addition of ammonium chloride is most effective.

On the other hand, as one of the drawbacks of sodium sulfate decahydrate, it is known that sodium sulfate decahydrate and its eutectic show anharmonic melting. That is, sodium sulfate decahydrate is separated into two phases, that is, a saturated aqueous solution of sodium sulfate and a solid of sodium sulfate during melting, and the solid of sodium sulfate has a higher density than that of the saturated aqueous solution and thus precipitates at the bottom of the container. Will end up. When this separation system is cooled, crystals of sodium sulfate decahydrate are formed on the precipitated sodium sulfate decahydrate, which acts as a barrier, and the remaining sodium sulfate decahydrate is combined with water to form sodium sulfate decahydrate. To prevent becoming. Therefore, by repeating solidification-melting, anhydrous sodium sulfate precipitates and does not contribute to the phase change, which is a problem that the heat storage amount decreases.
In addition, separation of the supercooling preventive agent occurs at the same time during the above separation, which causes a problem that supercooling easily occurs.

In order to solve this problem of phase separation, a polyvalent metal ion-bonded crosslinked product of wood pulp, methylcellulose, starch, alginate, polyacrylic acid is generally used as a phase separation inhibitor (Japanese Patent Laid-Open No. 54-54). No. 16387), carboxymethyl cellulose (JP-A-60-11575), silica gel, attapulgite-type clay (US Pat. No. 3,986,969), etc. may be added to increase the viscosity to a so-called gel state. Being tried.

[0008]

However, the conventional sodium sulfate decahydrate heat storage material composition has a clear phase change temperature, but the difference between the solidification temperature and the melting temperature is 4-5. As high as 0 ° C, the heat storage composition had to be cooled to a lower temperature to solidify. Therefore, if this is applied to an air conditioning cooling system, there is a drawback that the load on the cooler increases. Although this drawback has been improved in terms of hardware, the heat storage material itself has not been improved yet.

Further, in order to solve the phase separation problem of the sodium sulfate decahydrate heat storage material composition, a conventional phase separation inhibitor whose aqueous dispersion is alkaline or neutral is added. However, the present situation is that the ammonium salt in the eutectic mixture of sodium sulfate and ammonium salt is decomposed by repeated solidification-melting, and is not satisfactory in terms of long-term stability.

Therefore, a first object of the present invention is to provide a heat storage material composition having a clear phase change temperature and having a small difference between the solidification temperature and the melting temperature, which is useful for heat storage in a low temperature range.

A second object of the present invention is to provide a heat storage material composition which can achieve the above objects and is excellent in long-term stability.

[0012]

As a result of various investigations to solve the above problems, the present inventors have found that sodium sulfate decahydrate as a main component and ammonium salt or urea of a freezing point depressant that has been reported so far has been used. By adding a small amount of polyhydric alcohol to the latent heat storage material composition containing, a latent heat storage material composition for an air conditioning cooling system having a clearer phase change temperature and a small difference between the solidification temperature and the melting temperature is obtained. The present invention has been completed and the present invention has been completed.

It has also been found that, in this latent heat storage material composition, by adding 5 to 30 parts by weight of a phase separation inhibitor, a further excellent effect on heat history stability can be obtained. The present invention will be listed below in (1) to (5).

(1) 10 to 35 parts by weight of ammonium salt and / or urea as a freezing point depressing agent and 100 parts by weight of polyhydric alcohol as a phase change temperature adjusting agent to 100 parts by weight of sodium sulfate decahydrate as a main agent. .About.5 parts by weight and a phyllosilicate mineral having a pH of 7 or less as a phase separation inhibitor and / or a water-containing amorphous silicon dioxide 5 having a pH of 7 or less.
It is a latent heat storage material composition containing about 30 parts by weight.

(2) In the latent heat storage material composition of (1) above, the ammonium salt is selected from the group consisting of ammonium chloride, ammonium bromide, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium hydrogen carbonate and ammonium zinc chloride. The latent heat storage material composition is one or two or more compounds.

(3) In the latent heat storage material composition of (1) or (2), the polyhydric alcohol is ethylene glycol, propylene glycol, 1,3-propanediol, hexanediol, octanediol, glycerin, diethylene glycol, 1 selected from the group consisting of dipropylene glycol and polyethylene glycol
It is a latent heat storage material composition that is a compound of one kind or two or more kinds.

[0017]

[0018]

The present invention will be described in more detail below. The sodium sulfate decahydrate used as the main component in the latent heat storage material composition of the present invention is a compound represented by the chemical formula Na ₂ SO ₄ .10H ₂ O, which is usually used experimentally and industrially. It is a thing.

The ammonium salt used as the freezing point depressant in the present invention is a salt of ammonia with an organic acid or an inorganic acid and is a salt having NH ₄ ⁺ as a cation component. Of these, ammonium chloride, ammonium bromide, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium hydrogen carbonate, zinc ammonium chloride and the like are preferable.

The urea used as the freezing point depressant is a compound represented by the chemical formula (NH ₂ ) ₂ CO, which is usually used experimentally and industrially.

The freezing point depressant is used in an amount of 10 to 35 parts by weight, preferably 15 to 25 parts by weight, based on 100 parts by weight of the main ingredient, sodium sulfate decahydrate. If the content is less than 10 parts by weight, the freezing point depression is insufficient, while if it exceeds 35 parts by weight, the amount of heat storage is reduced, which is not preferable.

The polyhydric alcohol used as the phase change temperature adjusting agent in the latent heat storage material composition of the present invention is an organic compound having two or more alcoholic hydroxyl groups in one molecule, such as diol, triol and tetraol. , Pentaol, hexaol, alkylene oxide adducts thereof, polyalkylene oxide and the like. Among them, ethylene glycol, propylene glycol, 1,3-propanediol, butanediol,
Hexanediol, octanediol, glycerin, diethylene glycol, dipropylene glycol, polyethylene glycol and the like are preferably used.

The polyhydric alcohol has a function of reducing the difference (ΔT) between the melting temperature and the solidification temperature of the latent heat storage material composition. The smaller this ΔT, the clearer the phase change, and when the latent heat storage material composition is cooled to solidify,
It is not necessary to cool to below the freezing point and the load on the cooler can be reduced.

The polyhydric alcohol is used in an amount of 0.3 to 5 parts by weight, preferably 1.5 to 3 parts by weight, based on 100 parts by weight of sodium sulfate decahydrate as the main ingredient. If this amount is less than 0.3 part by weight, ΔT cannot be sufficiently reduced, while if it exceeds 5 parts by weight, the heat storage amount and the thermal history stability are reduced.

Next, in the latent heat storage material composition of the present invention containing a phase separation inhibitor, the one used as the phase separation inhibitor is called a solid acid, which is a proton donor or an electron acceptor. As long as it is solid, for example,
Mineral clays belonging to sulfide minerals, oxide minerals or phyllosilicate minerals, inorganic compounds such as acid clay, aluminum oxide, vanadium oxide, silicon dioxide, acidic oxides such as silica-alumina mixed with silica and alumina, cation exchange resins, etc. It can be used alone or as a mixture thereof. Among them, kaolinite clays having a pH of 7 or less, such as kaolinite, halloysite, dickite, and bentonite, which are classified as phyllosilicate minerals, and pH 7
The following water-containing amorphous silicon dioxide is preferably a powder having a particle size such that it can pass through a Tyler standard sieve of 60 mesh (JIS standard). Among these phase separation inhibitors, they have particularly good water dispersibility and are thermally stable.

These phase separation inhibitors are used in an amount of 5 to 30 parts by weight, preferably 8 to 20 parts by weight, based on 100 parts by weight of the main ingredient, sodium sulfate decahydrate. If the blending amount is less than 5 parts by weight, sufficient heat history stability cannot be obtained, while if it exceeds 30 parts by weight, the amount of heat storage becomes low and the efficiency as a latent heat storage material decreases.

The latent heat storage material composition of the present invention to which such a phase separation inhibitor is added can increase the viscosity of the phase, stabilize the aqueous dispersion thereof on the acidic side, and prevent the decomposition of ammonium salts. Therefore, this latent heat storage material composition has a stable thermal history and can withstand repeated use sufficiently as compared with the latent heat storage material composition to which a phase separation inhibitor has been added, which has been conventionally used.

The phase separation inhibitor used in the present invention is
The amount can be appropriately increased or decreased depending on the shape of the container filled with the latent heat storage material composition and the amount of the supercooling inhibitor added.

In the latent heat storage material composition of the present invention, sodium tetraborate decahydrate (Na ₂ B ₄ O ₇ .10H ₂ O) may be added to prevent supercooling.
In this case, the added amount is preferably 3 to 5 parts by weight with respect to 100 parts by weight of sodium sulfate decahydrate as the main ingredient.

In addition, the latent heat storage material composition of the present invention comprises
For the purpose of improving the wettability of sodium sulfate decahydrate to the phase separation inhibitor, β-naphthalene sulfonate sodium condensate, creosote oil sodium sulfonate condensate, melamine resin sodium sulfonate, lignin sulfonate sodium, A surfactant such as nonylphenol polyoxyethylene ether or sodium gluconate is added to the extent that the latent heat storage characteristics are not affected, for example, 0.05 to 0.
It is also possible to reduce the viscosity in the system by adding 5% by weight.

[0032]

EXAMPLES The present invention will be described below based on examples.
The invention is not limited to these examples. The melting point and the heat storage amount were measured by a JIS K 7122 transition heat measuring method, and were measured by a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd.). Formulation examples of the composition of the present invention and their test values are shown in Table 1, and formulation examples of the comparative sample composition and their test values are shown in Table 2. All units of the formulation shown in the table below are parts by weight.

[0033]

[Table 1]

[0034]

[Table 2]

Next, in order to improve the thermal history stability of the latent heat storage material composition, an attempt was made to add various phase separation inhibitors. In the test, the following sample was used as a phase separation inhibitor. Sample 1 Kaolinite (Tyler standard sieve 200 mesh pass) pH 5.9 Sample 2 Kaolinite (Tyler standard sieve 60 mesh pass) pH 5.9 Sample 3 Kaolinite (Tyler standard sieve 200 mesh pass) pH 6.5 Sample 4 Halloysite (Tyler standard sieve 60) PH 5.9 Sample 5 Amorphous Silicon Dioxide (Tyler Standard Sieve 60 mesh pass) pH 6.0 Sample 6 Amorphous Silicon Dioxide (Tyler Standard Sieve 60 mesh pass) pH 7.5 Sample 7 DEAE-Cellulose (Tyler Standard Sieve 60 mesh pass) pH 7.5 Sample 8 Amorphous silicon dioxide (Tyler standard sieve 60 mesh pass) pH 10.5 Sample 9 Attapulgite (Tyler standard sieve 60 mesh pass) pH 7.5 Sample 10 0.1N hydrochloric acid pH 1.0

However, the pH referred to here is the pH of a sample aqueous solution obtained by placing 2.5 g of a sample in a glass stoppered Erlenmeyer flask, adding 50 ml of water, heating, and immediately cooling to room temperature after boiling.
Is measured.

Various latent heat storage material compositions prepared by blending the above Samples 1 to 10 with any one of the above-mentioned Formulation Examples 4, 8 and 10 which are compositions of the present invention were carried out at 15 ° C. for 5 hours and at 0 ° C. for 4 hours.
A time cycle test was performed, and the change in the amount of heat storage of each latent heat storage material composition after repeating 300 times was measured. Sample 1
The composition examples of the composition using 5 and their test values are shown in Table 3.
Table 4 shows formulation examples of the composition in which the sample 1 was used in an excessively small amount and in an excessively large amount, and formulation examples of the composition in which the samples 6 to 10 were used, and their test values.

[0038]

[Table 3]

[0039]

[Table 4]

As described above, in the latent heat storage material composition of the present invention, with respect to the latent heat storage material composition containing sodium sulfate decahydrate as a main component and an ammonium salt of a freezing point depressant or urea in a predetermined amount. By adding a predetermined small amount of polyhydric alcohol, the phase change temperature could be clarified and the difference between the solidification temperature and the melting temperature could be reduced without lowering the heat storage amount.

In addition, in the latent heat storage material composition obtained by adding 5 to 30 parts by weight of a phase separation inhibitor to this latent heat storage material composition, the decrease in the latent heat storage amount due to repeated solidification and melting is small and the thermal history stability is high. It was able to exert an excellent effect on.

Therefore, the latent heat storage material composition of the present invention has a low temperature (5 to 5) suitable for an air conditioning system for a house or a building.
Since the heat can be stored in the air conditioning temperature range of 10 ° C.), it can be easily applied to the existing heat storage tank, and the number of facilities can be reduced. Further, since the heat can be stored by using the midnight power, the peak of the daytime power demand can be leveled, and the latent heat storage material composition is highly energy-saving.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Shinoda 7-35 Higashiohisa Arakawa-ku, Tokyo Asahi Denka Kogyo Co., Ltd. (72) Inventor Mariko Chiba 7-35 Higashiohisa Arakawa-ku Tokyo Asahi Denka Kogyo Co., Ltd. (72) Inventor Makoto Kusuma 4-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Electric Power Technology Research Institute, Tokyo Electric Power Co., Inc. (72) Masatake Otake 4 Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa No. 1 Inside the Electric Power Technology Laboratory, TEPCO Co., Ltd. (72) Makoto Sano 2-12-1, Botan, Koto-ku, Tokyo Inside Maekawa Manufacturing Co., Ltd. (72) Seiichi Sakuma 2--12, Botan, Koto-ku, Tokyo No. 1 Inside Maekawa Co., Ltd. (72) Inventor Hiroyuki Oka 2-12-1, Botan, Koto-ku, Tokyo Inside Maekawa Co., Ltd. (72) Inventor Naritake Kawasaki 1-12-6 Hachimandai, Isehara City, Kanagawa Prefecture (56) Reference JP-A 59-113082 (JP, A) JP-A 60-181185 (JP, A) JP-A 60-181186 (JP, A) JP-A-58-17187 (JP, A) JP-A-61-272281 (JP, A) JP-A-59-197486 (JP, A) JP-A-60-262882 (JP, A) JP-A-63-218786 ( (58) Fields investigated (Int.Cl. ⁷ , DB name) C09K 5/06 F28D 20/00

Claims (3)

(57) [Claims] 1. A main agent, sodium sulfate decahydrate 1
To 100 parts by weight, 10 to 35 parts by weight of ammonium salt and / or urea as a freezing point depressant, 0.3 to 5 parts by weight of polyhydric alcohol as a phase change temperature adjusting agent , and phase separation
Phyllosilicate minerals having a pH of 7 or less as an inhibitor, and
5 or 3 hydrous amorphous silicon dioxide having a pH of 7 or less
A latent heat storage material composition containing 0 part by weight . 2. The latent heat storage material composition according to claim 1, wherein the ammonium salt is selected from the group consisting of ammonium chloride, ammonium bromide, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium hydrogen carbonate and zinc ammonium chloride. A latent heat storage material composition which is a compound of one kind or two or more kinds. 3. The latent heat storage material composition according to claim 1 or 2, wherein the polyhydric alcohol is ethylene glycol, propylene glycol, 1,3-propanediol, hexanediol, octanediol, glycerin, diethylene glycol, or diethylene glycol. 1 selected from the group consisting of propylene glycol and polyethylene glycol
A latent heat storage material composition which is a compound of one kind or two or more kinds.