JPH0329108B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat storage material composition that stores solar heat, electrical energy, etc. and is used for hot water supply and space heating.

Configuration of conventional examples and their problems In recent years, research has been actively conducted on the application of latent heat storage materials, which have a large heat storage density and can extract heat at a constant temperature, to hot water supply, space heating, etc. As a latent heat type heat storage material, a hydrated salt type heat storage material is considered to be a promising material in terms of heat storage density, cost, and safety. However, hydrated salt type heat storage materials generally have problems such as overcooling and difficulty in phase separation, which has been a major obstacle in practical use.

For example, in order to use hydrated salts such as CH ₃ COONa and 3H ₂ O as a heat storage material, and to effectively use the latent heat of fusion during solidification for heating, etc., it is necessary to repeat melting and solidification smoothly. be. For this reason, a small amount of a supercooling prevention base material is usually added to the heat storage material. Here, the supercooling prevention base material is a material that is present in the heat storage material and immediately exhibits a heterogeneous nucleation effect when the heat storage material in a liquid state is cooled even slightly below its melting point without dissolving. , which has the effect of generating microcrystals of the heat storage material on its surface and promoting solidification. CH ₃ COONa・
As a base material for preventing supercooling of 3H ₂ O,
As shown in Publication No. 27301, CH ₃ COONa・
There is sodium pyrophosphate decahydrate Na ₄ P ₂ O ₇ 10H ₂ O whose surface is coated with 3H ₂ O.
2% by weight of Na ₄ P ₂ O ₇・10H ₂ O was added.
CH ₃ COONa・3H ₂ O successfully repeated melting and solidification in a heat cycle test of 70 to 40°C over 1000 times.

Although the detailed cause of the supercooling prevention function of Na ₄ P ₂ O ₇・10H ₂ O is not clear at present,
CH ₃ COONa・3H ₂ O crystals are formed on the surface of Na _{4 P 2} O ₇・10H ₂ O particles.
It is thought that even after 3H ₂ O has melted again, some trace remains, which effectively acts on the crystallization of CH ₃ COONa.3H ₂ O. Even if a simple adsorbent such as Al ₂ O ₃ , carbon black, etc. is treated in the same way as Na ₄ P ₂ O ₇ /10H ₂ O, it will temporarily have a supercooling prevention function, but the function will soon disappear. The simple CH ₃ COONa・
This cannot be explained by the adsorption theory of Na ₄ P ₂ O ₇ and 10H ₂ O on 3H ₂ O. It can be said that Na ₄ P ₂ O ₇ ·10H ₂ O has a unique regeneration function.

On the other hand, CH ₃ COONa・3H ₂ O was used in a body warming device,
For example, the biggest advantage of using it as a heat storage type hot vest is that it becomes cordless after heat storage is completed.
Considering practicality, it must be able to complete heat storage in a short time and maintain heat dissipation for several hours. CH ₃ COONa・3H ₂ O enables several hours of heat dissipation time
The amount of heat is essentially large and the thickness is large, and in order to complete heat storage in a short time, it is necessary to increase the output of a heater such as a heater wire. The heat supplied from the heater wire during heat storage is CH ₃ COONa.
It is spent on heat storage in 3H ₂ O and heat radiation loss to the outside. The lower limit of temperature control of CH ₃ COONa・3H ₂ O by heater wire heating is the melting point of CH ₃ COONa・3H ₂ O 58
℃, the upper limit is Na ₄ P ₂ O ₇ , which is the base material for preventing supercooling.
It is carried out with a heat-resistant temperature of 10H ₂ O. Subsequent research revealed that the heat resistance temperature of Na ₄ P ₂ O _{7.10H 2} O is approximately 80°C. Then, the temperature control range of CH ₃ COONa/3H ₂ O by heater wire heating is approximately 20°C, and it is extremely difficult to control within this temperature range when considering the variations in temperature controllers and products. Furthermore, in a state where the heater wire and part of the CH ₃ COONa/3H ₂ O storage container are extremely insulated for some reason while the current is being applied, that is, in a local heat retention state, there is no heat radiation loss from the insulated parts to the outside. Almost no heat is released from the heater wire.
CH ₃ COONa・3H ₂ O and Na ₄ P ₂ O ₇・10H ₂ O are supplied. As a result, Na ₄ P ₂ O ₇・
10H ₂ O is exposed to temperatures above 80°C. As a result, the supercooling prevention function of Na ₄ P ₂ O ₇ · 10H ₂ O deteriorated, and the latent heat of fusion of CH ₃ COONa · 3H ₂ O could not be used effectively.

OBJECTS OF THE INVENTION The present invention solves these conventional problems, and aims to provide a supercooling prevention material that has a high heat resistance and a stable supercooling prevention function.

Structure of the Invention In order to achieve this object, the supercooling prevention material of the present invention is obtained by coating the surface of a porous adsorbent onto which a supercooling prevention base material is adsorbed with a latent heat type heat storage material.

With this configuration, the base material for preventing supercooling can be held in the porous adsorbent, and the heat resistance commensurate with the adsorption energy at that time can be imparted to the base material for supercooling prevention.

Description of examples Examples of the present invention will be described below.

Na ₄ P ₂ O ₇・10H ₂ O50 as a base material to prevent supercooling
50 parts by weight of distilled water was added to the parts by weight, and the mixture was heated to about 80°C to completely melt it. 40 parts by weight of carbon powder (100 mesh) was added to the Na ₄ P ₂ O ₇ aqueous solution, stirred, and naturally cooled. Thereafter, the carbon powder layer precipitated at the bottom was taken out and left at room temperature. This allows the surface and interior of the carbon powder to
A carbon powder treated product with Na ₄ P ₂ O ₇ ·10H ₂ O crystals attached was obtained. This was added to 100 parts by weight of CH ₃ COONa.3H ₂ O which had been heated to 70° C. and completely melted, and the mixture was kept at 70° C. for about 1 hour while stirring and mixing. Thereafter, it was naturally cooled, and the lower layer treated with carbon powder was taken out and left at room temperature. As a result, the Na ₄ P ₂ O ₇・
CH ₃ COONa・ inside and on the surface of the 10H ₂ O crystal
A supercooling prevention material to which 3H ₂ O was attached was obtained. Add 2 parts by weight of this supercooling prevention material to CH ₃ COONa・3H ₂ O100
The mixture was poured into parts by weight and continuously heated at 85°C in a constant temperature bath.
Then take it out after any elapsed time and the supercooling will be 40
We tracked whether it would break at temperatures above ℃. Shown in Japanese Patent Publication No. 58-27301 as a comparative sample
CH ₃ COONa・3H ₂ O 100 parts by weight and Na ₄ P ₂ O ₇・
A composition consisting of 10 parts by weight of H ₂ O2 was simultaneously subjected to the experiment. As a result, while the comparison sample underwent supercooling in about 10 hours, the sample using the supercooling prevention material according to the present invention repeatedly melted and solidified stably even after 1000 hours. Also, instead of carbon powder
A similar improvement in heat resistance temperature was confirmed when Al ₂ O ₃ powder was used.

In this way, we were able to improve the heat resistance temperature by about 5 degrees Celsius, from 80 degrees Celsius to 85 degrees Celsius. The cause of this will be discussed below. In the case of the supercooling preventive material used in the comparison sample, the heat resistance temperature of its base material itself (Na ₄ P ₂ O ₇ · 10H ₂ O) is the upper limit temperature when used as a supercooling preventive material. In other words, the upper limit temperature of the supercooling prevention material that has the supercooling prevention function matches the melting point (80°C) of Na ₄ P ₂ O ₇ 10H ₂ O, and the temperature that is formed on the surface of Na ₄ P ₂ O ₇ 10H ₂ O It is thought that the traces of crystallization of CH ₃ COONa.3H ₂ O disappear with the melting of its parent material, Na ₄ P ₂ O _{7.10H 2} O. On the other hand, the supercooling prevention material according to the present invention is based on Na ₄ P ₂ O ₇ which is the base material for supercooling prevention.
10H ₂ O is adsorbed onto a porous adsorbent such as carbon powder or alumina powder, giving it heat resistance commensurate with the adsorption energy. In other words, the porous adsorbent acts as a holder for the base material to prevent supercooling.
Contains traces of crystallization of CH ₃ COONa・3H ₂ O
It can strongly supplement Na ₄ P ₂ O ₇・10H ₂ O. It is thought that for this reason, the heat resistance temperature as a supercooling prevention material could be increased by about 5°C.

In the above example, CH ₃ COONa・
3H ₂ O, Na ₄ P ₂ O ₇ as a base material to prevent supercooling.
_10H2O was used. The reason why carbon powder and alumina powder were used in this example is that their pore diameters are large (500 Å or more) and can sufficiently capture relatively heavy molecules such as Na ₄ P ₂ O ₇ 10H ₂ O. It is.

In the above example, CH ₃ COONa・3H ₂ O−
Although the description has been limited to the Na ₄ P ₂ O ₇・10H ₂ O system, other systems such as Na ₄ SO ₄・10H ₂ O−Na ₂ B ₄ O ₇・10H ₂ O
It goes without saying that this method can also be applied to other systems.

Effects of the Invention As stated above, the most important point of the present invention is that the heat resistance of the base material for preventing supercooling is improved by the adsorption energy when the base material adsorbs to the porous adsorbent. Hydrated salt type heat storage materials use a hydrated salt type base material to prevent supercooling.
It is fully applicable to hydrated salts other than CH ₃ COONa and 3H ₂ O. Therefore, the supercooling prevention material according to the present invention has a wide range of applications and is effective in that it can increase the heat resistance temperature of the supercooling prevention substrate.

Claims (1)

[Scope of Claims] 1. A supercooling prevention material in which the surface of a porous adsorbent on which a supercooling prevention substrate is adsorbed is coated with a latent heat type heat storage material. 2 CH ₃ COONa・3H ₂ O as a latent heat type heat storage material,
The supercooling prevention material according to claim 1, wherein Na ₄ P ₂ O ₇ is used as the supercooling prevention base material, and carbon powder or alumina powder is used as the porous adsorbent.