JPH0362194B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD 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 supercooling and phase separation, which poses a major obstacle in practical use. For example, when using hydrated salts such as CH ₃ COONa and 3H ₂ O as a heat storage material, in order 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
In a heat storage material, when the heat storage material in a liquid state without being dissolved away is cooled even slightly below its melting point, it immediately exerts a heterogeneous nucleation effect and generates microcrystals of the heat storage material on its surface. It has the effect of promoting solidification. CH ₃ COONa・
As a base material for preventing supercooling of 3H ₂ O,
As shown in Publication No. 27301, there is sodium pyrophosphate Na ₄ P ₂ O ₇ . 2% by weight of Na ₄ P ₂ O ₇・10H ₂ O was added.
CH ₃ COONa・3H ₂ O repeatedly melted and solidified smoothly in the heat cywal test at 70 to 40°C over 1000 times. 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.
3H ₂ O, is used for heat storage and heat loss to the outside. Temperature control of the heat storage material by heater wire heating is performed between a lower limit of 58° C., the melting point of CH ₃ COONa.3H ₂ O, and an upper limit of the heat resistance temperature of Na ₄ P ₂ O ₇ , which is a supercooling prevention material. Subsequent research revealed that the heat-resistant temperature of Na ₄ P ₂ O ₇ is approximately 80°C. However,
The temperature of the heater wire itself during heat storage is 80℃ or higher (actual value)
becomes. There is no problem with normal energization, but for some reason during energization the heater wire and CH ₃ COONa
3H ₂ O When a part of the storage container is extremely insulated,
In other words, when local heat is maintained, heat loss to the outside is reduced, and almost no heat is emitted by the heater wire.
CH ₃ COONa・3H ₂ O is supplied. the result,
Easily, CH ₃ COONa・3H ₂ O, Na ₄ P ₂ O ₇ at 80℃
exposed to temperatures above Then,
It was not possible to effectively utilize the latent heat of fusion of Na ₄ COONa・3H ₂ O. OBJECTS OF THE INVENTION The present invention solves these conventional problems and aims to provide a heat storage material composition that has a high heat resistance temperature and repeats stable melting and solidification. Structure of the Invention In order to achieve this object, the heat storage material composition of the present invention includes a heat storage material composed of CH ₃ COONa and 3H ₂ O;
It consists of a supercooling prevention material consisting of Na ₄ P ₂ O ₇ and a hydrolysis product consisting of Na ₂ HPO ₄ . Due to this composition, it is a supercooling prevention material.
Na ₄ P ₂ O ₇ and its hydrolysis product Na ₂ HPO ₄
It can be stabilized by dissociation equilibrium with Description of Examples The detailed cause of the supercooling prevention function of Na ₄ P ₂ O ₇ is not clear at present, but once CH ₃ COONa 3H ₂ O crystals were formed on the surface.
It is thought that some trace remains on the surface of the Na ₄ P ₂ O ₇ particles even after CH ₃ COONa・3H ₂ O has melted again, and that this effectively acts on the crystallization of CH ₃ COONa・3H ₂ O. It will be done. Simple adsorbents such as Al ₂ O ₃ , carbon black, etc., as well as Na ₄ P ₂ O ₇ .
Even if treated in the same way as 10H ₂ O, it temporarily has a supercooling prevention function, but the function immediately deteriorates, so the simple CH ₃ COONa・3H ₂ O
This cannot be explained by the Na ₄ P ₂ O ₇ adsorption theory. Na ₄ P ₂ O ₇
It can be said that it has a unique reproducing function. We aimed to improve the heat resistance temperature while maintaining this specificity of Na ₄ P ₂ O ₇ . In particular, Na ₄ P ₂ O ₇・10H ₂ O
The research focused on its own heat resistance. Examples of the present invention will be described below. 8 g of CH ₃ COONa・3H ₂ O as a heat storage material, 0.16 g (2 wt%) of Na ₄ P ₂ O ₇ as a supercooling prevention material, and anhydrous as a hydrolysis product of the supercooling prevention material.
Na ₂ HPO ₄ 0.16g (2wt%) inner diameter 8mm, length 150
It was stored in a mm cylindrical glass container and the end was sealed with a bar. This container was continuously heated at 85° C. in a constant temperature bath.
From time to time, it was taken out after an arbitrary elapsed time to monitor whether the supercooling was broken above 40°C. In addition,
Na ₄ P ₂ O ₇ is CH ₃ COONa・3H ₂ O 100 parts by weight
40 parts by weight of Na ₄ P ₂ O ₇・10H ₂ O were stored in the same volume and heated to 70°C to melt all of the CH ₃ COONa・3H ₂ O, which was then cooled again to solidify and deposit at the bottom.
The Na ₄ P ₂ O ₇ ·10H ₂ O portion was separated and dried.
CH ₃ COONa・3H ₂ O 8 as a comparison sample
g and 0.16 g of Na ₄ P ₂ O ₇ were simultaneously subjected to experiments. As a result, the comparison sample was approximately 10
Although supercooling occurs over time, the heat storage material assembly composition according to the present invention repeatedly melted and solidified stably even after 1000 hours had passed. Table 1 shows the heat resistance when the contents of Na ₄ P ₂ O ₇ and Na ₂ HPO ₄ are changed (However,
CH ₃ COONa has a trihydrate composition). Na ₄ P ₂ O ₇ ,
The amount of Na ₂ HPO ₄ added is preferably in the range of 0.1 to 10 wt%. If the amount added is smaller than this, the effect will be less.
If the amount is too large, the latent heat of fusion of CH ₃ COONa.3H ₂ O will decrease, so it is unsuitable.

【table】

[Table] In order to investigate the cause of the above effect, we conducted a composition analysis of the comparison sample after the test, and as a result, Na ₂ HPO ₄ was found. From this, the supercooling prevention function of Na ₄ P ₂ O ₇ is attributable to the surface of Na ₄ P ₂ O ₇ , where CH ₃ COONa・3H ₂ O has once solidified, and at high temperatures Na ₄ P It is thought that ₂ O ₇ caused hydrolysis and its surface disappeared. Na ₄ P ₂ O ₇
When is hydrolyzed, Na ₂ HPO ₄ is generated according to equation (1). Na ₄ P ₂ O ₇ + H ₂ O2Na ₂ HPO ₄ …(1) Therefore, the addition of Na ₂ HPO ₄ has the effect of shifting the dissociation equilibrium in equation (1) to the left, significantly reducing the rate of hydrolysis to the right term. The heat resistance of Na ₄ P ₂ O ₇ can be substantially increased. (Equation (2)). Na ₄ P ₂ O ₇ +10H ₂ O2Na ₂ HPO ₄ ...(2) Effects of the invention As stated above, the most important point of the present invention is that the heat resistance of the supercooling prevention material is increased by stabilizing its hydrolysis equilibrium. Generally, a hydrated salt type supercooling prevention material is used for a hydrated salt type heat storage material.
It is fully applicable to hydrated salts other than CH ₃ COONa and 3H ₂ O. Therefore, the heat storage material composition according to the present invention has a wide range of applications and is very effective in that it can increase the heat resistance temperature of the supercooling prevention material.

Claims (1)

[Claims] 1. A heat storage material consisting of CH ₃ COONa・3H ₂ O;
A heat storage material composition comprising a supercooling prevention material consisting of Na ₄ P ₂ O ₇ and a hydrolysis product consisting of Na ₂ HPO ₄ . 2 40-70wt% _CH3COONa , 0.1-10wt%
The heat storage material composition according to claim 1, comprising an aqueous solution containing Na ₄ P ₂ O ₇ and 0.1 to 10 wt% Na ₂ HPO ₄ .