JPH0124438B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat storage material composition, and more particularly to a heat storage material composition that does not cause a supercooling phenomenon.

[Technical background and explanation of conventional technology]

Utilizing the phenomenon that when a substance with an appropriate melting temperature and a large heat of fusion solidifies or melts, the substance releases or absorbs heat at a constant temperature corresponding to the heat of fusion, It is widely known that thermal energy can be stored in materials, and such materials are called heat storage materials.

Many substances have been known as heat storage materials to date, but in order to be practically usable as a heat storage material, a substance must absorb or release a large amount of heat (heat of fusion) when melting or solidifying. Since it is necessary that the melting temperature (solidification temperature) of the substance be within a practical temperature range, there are not many substances that satisfy this condition. Furthermore, even if these conditions are satisfied, it is very difficult to put the material to practical use unless the price of the material itself is appropriate.

For this purpose, a practical heat storage material is sodium sulfate decahydrate (Glauba salt, melting point: 32.5
), paraffin (melting point: 50-90°C), sodium thiosulfate pentahydrate (melting point: 48°C), sodium acetate trihydrate (melting point: 56°C) and trisodium imidobis sulfate (melting point: 43.5-50°C) ) are known (Japanese Unexamined Patent Publication No. 16035/1983, No. 102674 of 1983).

However, paraffin does not have a large heat of fusion, so the amount of heat it can store is small, and other hydrous salts cause a supercooling phenomenon when releasing heat, and do not solidify even when they reach the solidification temperature. The temperature decreases while it remains in the liquid phase (metastable state), and it solidifies only at an even lower temperature, so it has the disadvantage that thermal energy at a constant temperature cannot be recovered from the heat storage material.

In order to solve this problem, attempts have been made to prevent the occurrence of the above-mentioned supercooling phenomenon. For example, for sodium acetate trihydrate, as a nucleation component,
It is already known to add succinic acid disodium salt, succinic acid monosodium salt, succinic acid monosodium salt, or strontium acetate 1/2 hydrate (Japanese Unexamined Patent Publication No. 16035/1983).

The present inventor believes that sodium acetate trihydrate is not a very expensive substance, and its melting point allows it to supply water at an appropriate temperature for domestic use, assuming some heat loss. Recover waste heat from waste steam from equipment that uses steam,
Also, focusing on the fact that the temperature is suitable for recovering heat from sunlight, we searched for a substance that can prevent the supercooling phenomenon of sodium acetate trihydrate, and found acetamide. Through this process, we arrived at the present invention.

[Object of the invention and summary of the invention]

An object of the present invention is to provide a heat storage material composition that has an appropriate melting point and does not cause supercooling.

The present invention provides a heat storage material composition comprising sodium acetate trihydrate and acetamide, sodium acetate trihydrate, and acetamide.
A method for producing a heat storage material composition comprising heating a mixture of water salt and acetamide to melt the whole, and a heat storage material composition comprising heating a mixture of sodium acetate, acetamide and a small amount of water to melt the whole. This is a method for producing a material composition.

[Specific description of the invention]

According to the present invention, a heat storage material composition can be prepared by adding acetamide to sodium acetate trihydrate and heating the resulting mixture to melt the entire mixture and obtain a transparent solution. The temperature for heating the mixture is the melting point of sodium acetate trihydrate,
i.e. a temperature higher than 56°C (preferably around 60°C)
℃). During this heating, sodium acetate liberates three molecules of water, and sodium acetate itself dissolves in the liberated water of crystallization. Since the temperature does not change, in this melting the acetamide is uniformly dispersed in the concentrated aqueous solution of sodium acetate, and thermal energy of 56° C. is stored in the concentrated aqueous solution of sodium acetate.

Next, when the concentrated aqueous solution of sodium acetate is cooled and heat is removed from the concentrated aqueous solution, the concentrated aqueous solution releases the heat absorbed in the aforementioned melting process.
The whole solidifies to form crystals of sodium acetate trihydrate, but the temperature before and after that does not change, so when a concentrated aqueous solution of sodium acetate solidifies,
It can release heat at its melting point.

In the production of this heat storage material composition, 0.5 to 10 parts by weight, preferably 3 to 5 parts by weight of acetamide are used per 100 parts by weight of sodium acetate trihydrate. The amount of acetamide used is sodium acetate trihydrate 100
If the amount per part by weight is less than 0.5 parts by weight, it will not be possible to effectively prevent the supercooling phenomenon of a concentrated aqueous solution of sodium acetate trihydrate, and if the amount of acetamide used is more than 10 parts by weight, the melting point will be will no longer be shown.

The heat storage material composition of the present invention can be manufactured from anhydrous sodium acetate. In this case, it is preferable to add an amount of water corresponding to the trihydrate, but if it is a small amount, an excess of water can be used. The amount of acetamide added in this case is the same as above.

Since the heat storage material composition of the present invention can absorb or release heat at about 56° C., it can be used as a heat storage material composition for use in solar heat utilization and waste steam utilization. In addition, assuming some heat loss, the heat recovered by the heat storage material composition of the present invention has a temperature suitable for daily life such as bath water, wash water, heating, etc., so it is not suitable for use in these applications. suitable for

Next, examples of the present invention will be described, but the present invention is not limited to these examples.

Example 1 When 5 parts by weight of acetamide was added to 100 parts by weight of sodium acetate trihydrate and the resulting mixture was heated, it melted at a temperature exceeding about 60°C and became a transparent solution.

When this transparent solution was gradually cooled, the temperature stopped changing at 56°C, and after maintaining that temperature, the entire solution solidified.

Claims (1)

[Scope of Claims] 1. A heat storage material composition comprising sodium acetate trihydrate and acetamide. 2. A method for producing a heat storage material composition, which comprises adding acetamide to sodium acetate trihydrate and melting the whole by heating. 3. A method for producing a heat storage material composition, which comprises adding a small amount of water and acetamide to sodium acetate and heating the mixture to melt the whole.