JPH0748564A - Heat storage material composition - Google Patents

Abstract

PURPOSE:To provide the composition having a proper melting temperature and excellent in long-term capability of being recycled with a large amount of latent heat released or absorbed at the melting point. CONSTITUTION:The composition consists of 70-90wt.% sodium sulfate decahydrate, 3-17wt.% ammonium chloride, 1-13wt.% sodium chloride and 1-13wt.% ammonium sulfate and it also contains a supercooling inhibitor, such as borax or a silicate, and a phase separation inhibitor, such as carboxymethylcellulose.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage material composition suitable for cooling.

[0002]

2. Description of the Related Art As a heat storage material for cooling, one having a melting point within a temperature range of 5 to 10 ° C. has been considered useful. 5-1
As a composition example having a melting point near 0 ° C., conventional organic compounds include paraffin-based tetradecane (Japanese Patent Publication No. 53-24).
182: C ₁₄ H ₃₀ , melting point 5 ° C., pentadecane (C
₁₅ H ₃₂ , melting point 9.9 ° C., etc., polyethylene glycol # 400 (JP-A-62-1)
99680: 4-8 ° C.) and 1-decanol (5 ° C.) were known, but these substances are not used so much because their thermal conductivity is low and their heat of fusion is not so large. Is.

Regarding the inorganic compound system, several compositions of inorganic hydrates having a large heat of fusion and having a melting point in the vicinity of 5 to 10 ° C. have been reported. For example disodium hydrogen phosphate 1
Two-component composition with a dihydrate salt and dipotassium hydrogen phosphate hexahydrate (Japanese Patent Publication No. 52-11061: melting point 5 ° C.)
Has not completely solved the problem of supercooling and has a serious problem in practical use. A ternary composition of sodium sulfate decahydrate, ammonium chloride and ammonium bromide (Japanese Patent Publication No. 62-56912) has a melting point in the range of 6.3 to 10.1 ° C, but is stable for a long period of heat cycle. I am worried about my sex.

Three-component composition of sodium sulfate decahydrate, ammonium chloride and sodium chloride [MARIA TEL
KES, SOLAR ENERGY STORAGE, ASHRAE JOURNAL, SEPTEMBER,
1974] and the melting temperature is known to be 12.8 ° C. Also, a three-component composition of sodium sulfate, water and ammonium chloride (JP-A-2-9298)
8) has a melting point in the range of 8.6 to 9.6 ° C, but the freezing temperature is as low as 3.8 to 4.6 ° C, and the temperature of cold water for solidifying is as low as 1 to 2 ° C. Therefore, there is a problem that it cannot be used in a general-purpose refrigerator.

The melting temperature of the heat storage material for cooling has heretofore been considered to be preferably 5 to 10 ° C, more preferably 5 to 8 ° C. On the other hand, when it is used for insufficient cooling of the existing air conditioning equipment, it is necessary to use the existing general-purpose refrigerator (combined absorption refrigerator), and the temperature of the obtained cold water may be limited to about 4-5 ° C. Is high. Therefore, considering a heat storage material that solidifies with cold water at 4 to 5 ° C, the freezing point is 7 to 8 ° C, and it is preferable that the melting temperature be as low as possible. To be

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to
(1) Can be solidified with cold water at 4-5 ° C and has melting temperature of 1
To provide a heat storage material composition suitable for cooling, which satisfies conditions such as 0 to 13 ° C, (2) large latent heat amount at melting point, and (3) long-term heat recycling stability. is there.

[0007]

Means for Solving the Problems The present invention provides "1. 70 to 90% by weight of sodium sulfate decahydrate,
Ammonium chloride 3-17% by weight, sodium chloride 1-
A heat storage material composition comprising 13% by weight and 1 to 13% by weight of ammonium sulfate. 2. 0.1-10% by weight of at least one supercooling inhibitor selected from the group consisting of borax, silicates and cryolite, and selected from the group consisting of carboxymethyl cellulose, attapulghai clay and water-insoluble resin The heat storage material composition according to item 1, which contains 0.1 to 10% by weight of at least one phase separation inhibitor. 3. Sodium sulfate decahydrate 75-85% by weight, ammonium chloride 5-12% by weight, sodium chloride 4-
The heat storage material composition according to item 1 or 2, which contains 10% by weight and 4 to 10% by weight of ammonium sulfate. 4. The heat storage material composition according to any one of items 1 to 3, wherein the heat storage material composition has a melting point in the range of 10 to 13 ° C. 5. 5. The heat storage material composition according to any one of items 1 to 4, wherein the heat storage material crude product has a latent heat of fusion of 30.1 to 47.3 cal / g. 6. 1 to 5 wherein the supercooling inhibitor is borax
The heat storage material composition according to any one of items. 7. The phase separation inhibitor is a water-insoluble water-absorbent resin,
The heat storage material composition according to any one of items 1 to 6. Regarding

[0008]

The main component of the composition of the present invention is sodium sulfate 10
A hydrated salt having a melting point of 32.5 ° C. and a ca.
It has a latent heat of fusion of l / g. In the composition of the present invention, in order to obtain a heat storage material composition having a melting temperature of 10 to 13 ° C, ammonium chloride, sodium chloride and ammonium sulfate are blended as a melting point adjusting agent. The content of sodium sulfate hydrate in the composition of the present invention is 70-
90% by weight, preferably 75-85% by weight. When the amount of the salt is more than 90% by weight, the amount of the melting point adjusting agent blended is small, so that the melting temperature of the composition is 10 to 13 ° C.
If the amount of the salt is less than 70% by weight, the latent heat of fusion of the composition becomes small, which is not preferable.

The total content of the melting point adjusting agents is 10 to 30% by weight, preferably 15 to 25% by weight. Ammonium chloride, which has the greatest effect, is 3 to 3 per total weight of the composition.
It is 17% by weight, preferably 5 to 12% by weight. If the compounding amount of ammonium chloride is outside this range, the melting temperature will not be 10 to 13 ° C. Sodium chloride, when combined with ammonium chloride, can lower the melting temperature of the heat storage material composition containing sodium sulfate decahydrate as a main component to around 13 ° C. The content of sodium chloride is 1 to 13% by weight, preferably 4 to 10% by weight, which is the same as or less than the content of ammonium chloride.

Ammonium sulfate is not so effective as a melting point regulator as compared with ammonium chloride and sodium chloride. However, it was found that the addition of ammonium sulfate increases the amount of latent heat, possibly because ammonium ions and sulfate ions increase in the composition, and the behavior change during melting is also stable. The compounding amount of ammonium sulfate is 1 to 1.
3% by weight, preferably 4 to 10% by weight, more preferably the same as or less than the amount of ammonium chloride compounded. If the addition amount of sodium chloride and ammonium sulfate is less than 1% by weight or more than 13% by weight, the melting temperature does not reach 10 to 13 ° C.

The heat storage material composition of the present invention consists essentially of sodium sulfate decahydrate, ammonium chloride, sodium chloride and sodium sulfate, and further contains a supercooling inhibitor and a phase separation inhibitor. You can Examples of the supercooling preventive agent that can be used in the present invention include borax, silicate, and cryolite, with borax being preferred. The compounding amount of the phase separation inhibitor is 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the weight of the composition.

Examples of the phase separation inhibitor which can be used in the present invention include carboxymethyl cellulose, attapulghai clay, water-insoluble water absorbent resin, sodium alginate, gelatin, agar, wood pulp, silica gel, diatomaceous earth and the like. Of these, carboxymethyl cellulose, attapulgai clay, water-insoluble water-absorbent resin such as cross-linked polyacrylic acid salt, partially saponified vinyl acetate-acrylic acid copolymer, and starch-acrylic acid graft copolymer are preferable. The compounding amount of the supercooling inhibitor is 0.1 to 10% by weight, preferably 0.5, based on the weight of the composition.
~ 5% by weight. By using these phase separation inhibitors, a heat storage material composition having stable long-term recycling performance can be obtained.

The present invention is characterized in that it includes sodium sulfate hydrate and ammonium chloride, sodium chloride, or ammonium sulfate in a specific ratio, and even if one of the constitutions is lacking, it is out of the specific use ratio. However, the effect of the present invention is not exhibited.

[0014]

【Example】

Examples 1 to 13 Preparation method of heat storage material composition and its thermal evaluation Sodium sulfate decahydrate, ammonium chloride, sodium chloride and ammonium sulfate were mixed in the proportions shown in Table 1, and then borax was used as a supercooling inhibitor. 1.5 parts by weight with respect to 100 parts by weight of sodium sulfate-based hydrate, and a water-insoluble water-absorbent resin as a phase separation inhibitor (Sunwet
IM-1000 (manufactured by Sanyo Kasei Co., Ltd.) was added to 1.5 parts by weight of 100 parts by weight of sodium sulfate-based hydrate and stirred with a mixer to prepare a composition. At this time, it is very important to stir the composition until it is sufficiently homogeneous, and if the stirring is not sufficient, the amount of heat as designed cannot be obtained, and therefore care must be taken. The obtained composition was analyzed by DSC-10.
The amount of latent heat was measured in the temperature range of 40 ° C to 40 ° C. A 40 cc sample of the composition was placed in a 85 cc centrifuge settling tube, a thermocouple was inserted in the central part, sealed with a rubber stopper, and placed in a water tank at 5 ° C.
The temperature change pattern was measured by performing coagulation / melting recycling between and 15 ° C. In addition, the supercooling temperature during solidification, the solidification temperature and the average melting temperature were measured. The supercooling temperature represents the temperature when the supercooled state is broken. Further, as the supercooling breaks and the aged material solidifies, latent heat is released, so that the temperature rises. At this time, the highest temperature reached is the solidification temperature. The average melting temperature represents the average temperature from the start of melting to the end. The measurement results are shown in Table 1.

Compositions were prepared in the same manner as in the above-mentioned Examples in Comparative Examples 1 to 3, and their thermal evaluations were performed. The results are shown in Table 1.

[0016]

[Table 1]

From the above results, all the compositions of Examples 1 to 13 in which the composition ratio of sodium sulfate decahydrate-ammonium chloride-sodium chloride-ammonium sulfate is within the range described in claim 1 are average. The melting temperature is within the target temperature range of 10 to 13 ° C. Example 4
All of the compositions other than 12.4 ° C. are 11.8 ° C. or less and are compositions at lower temperatures within the target temperature range,
It can be seen that the heat storage material composition is suitable for cooling, which has a low heat extraction temperature in the system. The composition of Example 4 has a slightly higher melting point of 12.4 ° C., but has a heat storage amount of 35.
It can be seen that it is an excellent heat storage material composition having a very large value of 9 cal / g. Among the examples, the one having the lowest heat storage amount is 30.
It is 1 cal / g, which is 45.2 cal / cm ² per volume (specific gravity of these compositions is 1.50) and it is an excellent heat storage material that can store about half the amount of heat of ice. .

Comparative Examples 1 and 2 are compositions based on the above-mentioned publicly known technology, and are a three-component system of sodium sulfate decahydrate-ammonium chloride-sodium chloride. The composition of Comparative Example 1 has an average melting temperature of 12.6 ° C., which is within the target temperature range, but higher than any of the average melting temperatures of the compositions of Examples. In addition, the heat storage amount is as small as 21.5 cal / g, which is smaller than any of the compositions of Examples. Although the difference in heat storage amount between the composition of Example 3 and the composition of Comparative Example 1 is relatively small, the compositions of Example 3 are 11.3 ° C., and the compositions of Comparative Example 1 are It can be seen that the composition of Comparative Example 1 is higher than that of 12.6 ° C by about 1.3 ° C. From this, it can be seen that the composition of Example 3 has a larger effective amount of heat that can be utilized at a lower temperature than the composition of Comparative Example 1. The composition of Comparative Example 2 has a high average melting temperature of 13.1 ° C., which is outside the target temperature range. When used for cooling, it is desirable that the average melting temperature be as close to 10 ° C as possible. At 13.1 ° C, even if the average melting temperature is 23.9cal /
Even if it has a heat storage amount of g, it is considered that the effective heat amount that can be used for cooling is very small. Further, when the heat storage material composition is operated in the heat storage system, it is desirable that the difference between the average melting temperature and the solidification temperature is small. That is, when melting at the same temperature, the higher the solidification temperature is, the easier the solidification is, and the heat can be efficiently stored. The difference between the average melting temperature and the solidification temperature is about 5 ° C. or lower for the compositions of Examples 1 to 12 and 5.7 ° C. for the composition of Example 13. In comparison, the compositions of Comparative Examples 1 and 2 were 7.0 ° C, 6.9 ° C and about 7 ° C, respectively.
The difference from the example is about 2 ° C., indicating that the composition of the example can efficiently store heat. The composition of Comparative Example 3 is a composition in which the compounding amount of ammonium sulfate is out of the range of 1 to 13% by weight. As a result of measuring with DSC, 15 ° C and 20
Since it is a mixture of two components that have a melting peak at ℃, it is a composition that does not have a clear melting temperature, and the melting temperature is higher than the target temperature, so it cannot be used for cooling applications. .

In order to reproduce the actual use condition, 260 g of each of the samples of Example 3 and Comparative Example 1 was filled, and the change in the center temperature of the ball was measured by a thermocouple and recorded. . At this time, set the temperature of the water tank to 4 ° C and 15
The coagulation-melting pattern after the coagulation-melting is controlled by controlling the temperature between 0 ° C. and 100 times is repeated, is shown in FIG.

In FIG. 1, 0 to 6 hours is the solidification process of the heat storage material. The water temperature drops to 4 ℃ in 1 hour,
Thereafter, the temperature was kept at 4 ° C. for 5 hours. In both Example 3 and Comparative Example 1, the state did not change and the temperature dropped for 1 hour from the start. After 1 hour, the metastable supercooled state was broken and crystallization started. At this time, in order to release the latent heat of solidification, in both Example 3 and Comparative Example 1, the material temperature was raised and the product was made into a product. After the latent heat of solidification was released and the crystallization was completed, about 5 hours in Example 3 and about 4 and a half hours in Comparative Example 1, the temperature of the water tank became equal. In FIG. 1, 6 to 11 hours are the melting process of the heat storage material. From the 6th hour to the 7th hour, the water temperature increased to 15 ° C in 1 hour, and then 15 ° C was maintained for 4 hours. In Example 3, the temperature increased without changing the state for 1 hour from the start, the melting started from the 7th hour, and the melting continued until the point of 9 hours and a half.
The melting was complete and the temperature of the water bath was equalized. At this time, Example 3 melts at 10.4 ° C to 12.2 ° C, the melting curve also extends long parallel to the time axis near the melting point (from the 7th hour to the 9th and a half hours), and the heat is accumulated. It can be seen that a large amount of heat is released as the latent heat of fusion and is stably released. 1
When the heat storage amount of the sample after 00 times solidification and melting was measured using DSC, it was reduced from 30.1 cal / g to 26.5 cal / g, but it still has a large heat storage amount. The reduction of the heat storage amount in Example 3 was 12% less than the initial value.
In Comparative Example 1, as in Example 3, the temperature increased without changing the state from the start to the first hour, and the curve started to be inclined in the vicinity of the seventh hour so that the curve became parallel to the time axis. However,
The temperature did not become parallel to the time axis as in Example 3, but the temperature increased linearly until the 9th hour, and thereafter became equal to the temperature of the water tank. Comparative Example 1 is different from Example 3 in that
It can be seen that the composition does not have a melting curve parallel to the time axis, that is, it has no clear melting point. A heat storage material that does not have a clear melting point makes it difficult to extract heat stably in the system, even if it has a certain amount of heat.
System control is complicated and difficult to use. In Comparative Example 1, after coagulation and melting 100 times, 21.5 cal / g to 17.
It decreased to 6 cal / g, and the reduction rate was 18%. Probably because Example 3 contained ammonium sulfate in the composition, the melting temperature was stable even after 100 times of solidification and melting,
It can be seen that the composition is stable even for long-term use. In addition, the reduction rate of the heat storage amount is 12% compared to 18% of Comparative Example 1.
It can be seen that the composition is small and calorifically stable.

[0021]

According to the present invention, by mixing sodium sulfate decahydrate and a melting point adjusting agent in a special composition, 4-5 ° C.
It can be solidified with cold water and has a melting temperature of 10-13
It has a large latent heat of fusion at the melting temperature and has an excellent effect of long-term heat recycling stability.

[Brief description of drawings]

FIG. 1 is a graph showing a solidification / melting pattern of the present invention.

Claims (7)

[Claims] 1. A heat storage material roughening composition comprising 70 to 90% by weight of sodium sulfate decahydrate, 3 to 17% by weight of ammonium chloride, 1 to 13% by weight of sodium chloride and 1 to 13% by weight of ammonium sulfate. object. 2. At least one supercooling inhibitor selected from the group consisting of borax, silicate and cryolite.
10% by weight and 0.1-10% by weight of at least one phase separation inhibitor selected from the group consisting of carboxymethyl cellulose, attapulghai clay and water-insoluble resin
The heat storage material composition according to claim 1, which comprises: 3. A sodium sulphate decahydrate of 75 to 85% by weight, ammonium chloride of 5 to 12% by weight, sodium chloride of 4 to 10% by weight and ammonium sulfate of 4 to 10% by weight. The heat storage material composition described in 1. 4. The melting point of the heat storage material composition is 10 to 13.
The heat storage material composition according to any one of claims 1 to 3, which is in the range of ° C. 5. The heat storage material composition is 30.1-47.3.
The heat storage material composition according to any one of claims 1 to 4, which has a latent heat of fusion of cal / g. 6. The heat storage material composition according to claim 1, wherein the supercooling inhibitor is borax. 7. The heat storage material composition according to claim 1, wherein the phase separation inhibitor is a water-insoluble water absorbent resin.