JPS5922986A - Heat-accumulating material - Google Patents

Abstract

PURPOSE:To provide a heat-accumulating material having minimized super- cooling tendency and high stability with time, and useful for the accumulation of solar energy for room heating use, by using sodium acetate trihydrate and disodium hydrogen phosphate (hydrate) as essential components. CONSTITUTION:The objective heat-accumulating material can be prepared by mixing (A) 100pts.wt. of sodium acetate trihydrate with (B) 1-30pts.wt. of disodium hydrogen phosphate (hydrate) in terms of anhydride, and if necessary (C) a thickener such as sodium polyacrylate, a filler such as kaolin clay, asbestos powder, etc., and melting the mixture. EFFECT:A heat-accumulating material can be obtained only by charging the molten liquid into a container without using the coagulating process of the heat- accumulating material. It maintains stable crystal nucleus-forming effect even at a temperature of as high as about 90 deg.C, and repeats the heat-accumulating and heat-emitting steps in high stability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides sl-lium acetate trihydrate (CH3COONa.
3020) as a base material, and more specifically, it relates to a heat storage material that prevents supercooling as much as possible.

Traditionally, heat storage materials include those that utilize the sensible heat of substances;
One that uses latent heat is known.

Those that use latent heat have a larger amount of heat storage per unit volume and per unit weight than those that use sensible heat, and a wide variety of materials have been studied.

Inorganic hydrates are well known for indoor heating and solar energy storage. However, inorganic hydrates generally have drawbacks such as high supercooling and low crystallization speed, and are suitable for long-term (weekly to seasonal) heat storage and dissipation.
Many of them are not suitable for short-term (hours to days) heat storage and radiation.

Exceptionally, nitrates with low supercooling and high crystallization rate had drawbacks such as (1) low amount of heat storage per unit volume, (2) high cost (cost), and (2) high oxidation effect that corrodes the container.

Organic heat storage materials have also been proposed, but they have problems such as: (1) low heat transfer rate; (2) small amount of heat storage; (2) high loss 1.

Among the above-mentioned hydrates, sl-lium acetate hexahydrate (CH3COONa.5H2O) is attracting attention because of (1) advantageous in terms of loss (C) large amount of heat storage and (2) fast crystallization rate. However, at present, sodium acetate pentahydrate alone cannot be used as a heat storage material because of its large supercooling effect. Therefore, in recent years, attempts have been made to prevent supercooling by using a supercooling inhibitor in combination.
) (Japanese Unexamined Patent Publication No. 57-59981) has achieved considerable effects. However, in the heat storage material made of monohelium acetate hexahydrate and monohelium pyrophosphate decahydrate, supercooling may not be broken during the first cooling, and the material may be cooled to room temperature. In order to solve this problem, the mixture of monohelium acetate trihydrate and monolithium pyrophosphate decahydrate, which is in an appropriately cooled state, must be solidified by some method. The first problem is that it requires a complicated treatment process.

Furthermore, the crystal nucleation effect of sulfur pyrophosphate decahydrate on sulfur lithium acetate pentahydrate described above is stable if the heating temperature for the heat storage material is around 70°C;
If the temperature exceeds °C, it becomes unstable and supercooling appears, so the heating temperature of the heat storage material must be kept at about 70 °C.

It also had the disadvantage of being limited in its use.

The present inventor has developed a heat storage material based on sulfur acetate to thulium hydrate as a base material to 2 sulfur hydrogen phosphate to thulium Na,
By mixing Hpo4) (including hydrated salt), the heat storage material solidifies without supercooling from the first solidification, and does not crystallize even when heated to a high temperature of around 90°C. The present invention was completed by discovering that stable heat storage and radiation can be performed without losing the nucleation effect.

That is, the gist of the present invention is a heat storage material consisting of at least 1-sulfur acetate trihydrate and 2-sulfur hydrogen phosphate (including hydric salt).

Why does the heat storage material of the present invention solidify without supercooling from the first time it solidifies, and does it store and release heat stably without losing its crystal nucleation effect even when heated to high temperatures around 90°C? Not sure though.

Hydrogen phosphate 2 s 1 added to 1 s)-lium acetate trihydrate
This is thought to be due to the affinity of -lium (including hydrated salts).

Next, each component of the present invention will be explained.

So-1-lium acetate trihydrate serves as a base material for the heat storage material of the present invention.

Disodium hydrogen phosphate (including hydrates) is used as a crystal nucleating agent, and the amount used is 30% sodium acetate.
The amount is 1 to 50 parts by weight in terms of anhydride based on 100 parts by weight of aqueous salt. If it is less than 1 part by weight, the crystal nucleation ability is weak and supercooling tends to occur, and if it is more than 30 parts by weight, there will be a problem that the amount of heat storage will be reduced. Note that when disodium hydrogen phosphate aqueous salt is mixed with sodium acetate pentahydrate, it will melt once, but in the sodium acetate hexahydrate melt, the solubility of dibasic hydrogen phosphate decreases, and dihydrogen phosphate Su1
-Precipitated as fine particles of lithium, 2 liters of hydrogen phosphate
Shows effects similar to thulium.

In addition, in order to prevent precipitation of dihelium hydrogen phosphate in the heat storage material, thickeners such as sodium polyacrylate and fillers such as kaolin earth and asbenu powder are added as appropriate, and acetic acid Water may be added as appropriate for the purpose of adjusting the solidification rate of the sodium filtrate salt, other crystal nucleating agents may be appropriately added for the purpose of supporting crystal nucleation formation, and other crystal nucleating agents may be appropriately added for the purpose of adjusting the melting point of the heat storage material. Additives may be added as appropriate, and examples will be briefly described.

First, sodium acetate trihydrate and disodium hydrogen phosphate (
(including hydrates) in the required amount, add other additives as necessary, and heat and melt the mixture.

Next, the heat storage/radiation operation of the heat storage material of the present invention will be briefly described.

When the heat storage material of the present invention is heated, it first accumulates sensible heat corresponding to the specific heat of the same phase, and when it reaches the melting point, it stores the latent heat of fusion and melts, becoming a liquid. , accumulates sensible heat according to the specific heat of the liquid phase. Next, when this molten heat storage material is cooled and heat is extracted, sensible heat corresponding to the specific heat of the liquid phase is released, and when the material is cooled slightly below the solidification temperature, the disodium hydrogen phosphate crystal surface A crystal nucleus of sodium acetate hexahydrate is generated, and crystals of sodium 1-lium acetate trihydrate grow from the crystal nucleus as a starting point, thereby releasing latent heat of solidification with almost no supercooling. When solidified and further cooled, sensible heat corresponding to the specific heat of the solid phase is released.

Next, the present invention will be explained in more detail with reference to Examples. In the examples, "parts" indicate "parts by weight."

Example 1 1-lium acetate trihydrate 100 parts Disodium hydrogen phosphate 10 parts The above components were mixed,
The mixture was placed in a beaker and heated and melted at 70°C in a water bath to obtain a heat storage material.

Example 2 Mono-lithium acetate trihydrate 100 parts Dis-1-lium decahydrate hydrogen phosphate 10 parts Asbeth 1-powder
A heat storage material was obtained in the same manner as in Example 1 by mixing 10 parts of the above components.

Example 5 Mono-lium acetate trihydrate 100 parts Disodium hydrogen phosphate 10 parts Water
10 parts of the above components were mixed and a heat storage material was obtained in the same manner as in Example 1.

Example 4 Sodium acetate trihydrate 100 parts Disodium hydrogen phosphate dodecahydrate 10 parts Sodium polyacrylate 3 parts The above components were mixed and a heat storage material was obtained in the same manner as in Example 1.

Comparative example 1 Mono-lium acetate hexahydrate alone was used as a heat storage material.

Comparative Example 2 100 parts of 1-lium acetate hexahydrate 5 parts of 1-lium pyrophosphate decahydrate The above components were mixed and a heat storage material was obtained in the same manner as in Example 1.

Above are Examples 1 to 4. Obtained in Comparative Examples 1 and 2, 100
Table 1 shows the results of the second solidification temperature measurement, as well as the melting point and heat of fusion measurements before the cycle. In addition, since the heat storage materials obtained in Comparative Examples 1 and 2 did not solidify due to supercooling during the first solidification, seed crystals (fine crystal particles of sodium acetate trihydrate) were added from the second time. After solidifying once, the same test was repeated.

Table-1 *1 Melting point was determined from a differential scanning calorimetry (DSC) curve.

*2 Heat of fusion was measured using a differential scanning calorimeter.

Next, the heat storage materials obtained in Example 1 and Comparative Example 2 were heated and
3 types of cooling cycles (70℃030℃.

The measurement result of the coagulation temperature when 80°C←30°C, 90°C, 030°C) was repeated five times is shown in U-2.

Table 2 Regarding Comparative Example 2, seed crystals (1 to 3 lithium acetate)
The test was conducted after introducing aqueous salt (fine crystalline particles) and forcibly coagulating it once.

As shown above, the heat storage material of the present invention is the first heat storage material after mixing and preparation.
Since it solidifies without supercooling from the time of solidification, it has the advantage that it can be configured to omit the troublesome process of solidifying the heat storage material by some method.
Gah.

It maintains a stable crystal nucleation effect even at high temperatures around 90 degrees Celsius, and can be used as a heat storage material for indoor heating, solar energy storage, etc., as it repeatedly and stably stores and releases heat. It is also an excellent product that exhibits stable performance.

Patent applicant: Pentel Co., Ltd.

Claims (2)

[Claims] (1) 1-lium acetate trihydrate and 2-1-lium hydrogen phosphate
A heat storage material consisting of at least 30% of aluminum (including hydrated salts) and more. (2) Claim 1: 1 to 30 parts by weight of 2s-1-lium hydrogen phosphate (including hydric salt) in terms of anhydride based on 10 parts by weight of (2)-lium acetate trihydrate Heat storage material described in section.