JPS59149977A - Heat storing material - Google Patents

Abstract

PURPOSE:To impart pref. heat storing and dissipating characteristics to a heat storing material while suppressing an over-cooling phenomenon, by adding aluminum hydroxide to a heat storing material containing sodium carbonate decahydrate as one component. CONSTITUTION:To a heat storing material containing sodium carbonate decahydrate as one main component, at least 0.05wt% sodium carbonate decahydrate of aluminum hydroxide is added as an over-cooling inhibitor to obtain an objective heat storing material. By this method, an over-cooling phenomenon wherein sodium carbonate decahydrate is not coagulated even if it reaches a phase transformation temp. from a molten state can be suppressed and inconvenience such that said heat storing material can not dissipate heat even if it reaches a temp. at which heating is required can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention mainly relates to the amount of heat storage used for passive solar heating, greenhouse heating, and the like.

``Conventional configurations and their problems Storage of daytime solar heat during the winter and use of this for nighttime heating has been attempted in passive solar systems and greenhouses.In these systems, heat storage materials There are two types of materials used as heat storage materials: those that utilize the sensible heat of water, stones, etc., and latent heat storage materials that utilize the latent heat of materials during melting and solidification.In particular, the latter has a large amount of heat storage per unit volume. Many have characteristics such as storing and dissipating heat at a constant temperature,
Attention has been paid. There are various hydrates as heat storage materials suitable for use below 40"C in passive solar heating systems, and among them, sodium carbonate decahydrate has a latent heat of about eocal/ff. However, since the temperature of the melting process is approximately 36°C, useful materials can be obtained.

Generally, when using hydrates as latent heat storage materials,
Supercooling phenomenon during solidification (heat dissipation) becomes a problem. That is, it does not solidify even when it goes from a molten state to a phase transformation state, and it radiates heat and solidifies (8) after the temperature becomes considerably lower than the phase transformation temperature. This means that heat cannot be radiated even if the desired heating temperature is reached, which is inconvenient. When heating sodium carbonate decahydrate, it changes from decahydrate to heptahydrate at 32°C and from 36°C.
However, when cooled from 35°C or higher, the reverse process does not necessarily occur, especially when 1o
When producing aqueous salt, supercooling tends to occur, and 1o aqueous salt is produced only when the temperature drops below 6°C.

Purpose of the Invention In view of the above circumstances, the purpose of the present invention is to obtain sodium carbonate 1
This was done to suppress the supercooling phenomenon during solidification of 0-hydrate salt.

+1 composition of the invention The heat storage material of the present invention is a heat storage material mainly composed of sodium carbonate decahydrate, or a heat storage material obtained by mixing IJium 1ohydrate and other substances with aluminum hydroxide. Obtained by adding The feature of the present invention is that aluminum hydroxide is added to the heat storage material containing sodium carbonate decahydrate as one of its components in order to suppress supercooling phenomenon.
In addition, the presence or absence of other substances for the purpose of adjusting the phase transformation temperature as heat storage material components, thickeners, surfactants, etc. for improving properties does not change the basic structure of the present invention. This does not deviate from the spirit of the invention.

DESCRIPTION OF EXAMPLE 2 parts by weight of a cross-linked acrylic acid type compound were added to IJium decahydrate as a phase separation inhibitor, and aluminum hydroxide was added to 0.05, 0.05, 0.1 and 1 parts by weight of aluminum hydroxide, respectively.

6. A sample was prepared with 10 weight coefficients added, and the sample was approximately 302 mm.
was placed in a sealed polyethylene container, a thermocouple for measuring the sample temperature was inserted into the center of the sample, the specimen stored in the container was placed in a water tank, and the water temperature was repeatedly varied between 46°C and 1°C. The temperature profiles of melting and solidification are shown in the figure as typical temperature profiles when 6 weight percent of aluminum hydroxide is added and when no addition is made. In other words, in the solidification/melting curve (■) without additives, there is only a small step indicating the formation of heptahydrate at the solidification temperature of about 31°C, and a corresponding step showing melting at about 37°C during melting. Seen near τJ. On the other hand, in the case of adding 5'1 itltt of aluminum hydroxide, the solidification/melting curve shows a small step at about 32°C during solidification, similar to the case without addition, and 1000 ml of water at about 28°C. There are large steps indicating coagulation. Also, during melting, a large step corresponding to the melting of the 10711C salt is observed.

In this way, it is clear that aluminum hydroxide acts as a nucleus for the formation of sodium carbonate decahydrate.0.01.0.05 .0.1.

As a result of examining the temperature profile of the sample containing 1.5.10% by weight, the effect was recognized even at 41% by weight of 0.01 wt.
．． 06 Sodium carbonate decahydrate and sodium sulfate 1 were confirmed to be desirable to add at least Ji%
Mainly 1 is a eutectic mixture containing 0 hydrate salt in a ratio of 1 mole to 1 mole.
Regarding the heat storage material used in this study, a test film containing only borax, which has already been disclosed as an anti-supercooling agent for sodium sulfate decahydrate, did not exhibit a supercooling phenomenon when cooled from 36"C or higher. However, it was confirmed that supercooling was suppressed in the tests in which aluminum hydroxide was added.

Sodium carbonate of hydrated aluminum according to the invention 10
The supercooling suppressing effect on water salt can be obtained from a concentration as low as 0.06N, while there is no particular reason to limit the upper limit of the amount added from the viewpoint of the effect, but it may cause a decrease in the amount of heat storage. Practical - It is not desirable to add more than L20.

Effects of the Invention As described above, the present invention adds aluminum hydroxide as a supercooling inhibitor to a heat storage material containing sodium carbonate decahydrate as a main component or a heat storage material containing sodium carbonate decahydrate as a part of the component. This suppresses supercooling and improves storage and storage.
It has the advantage of providing heat dissipation properties.

[Brief explanation of the drawing]

The figure shows the temperature profile of solidification and melting in the case where hydrated aluminum oxide is added to sodium carbonate 1O hydrate and in the case where no aluminum oxide is added.

Claims (1)

[Claims] (1) Amount of heat storage characterized by containing at least sodium carbonate decahydrate and aluminum hydroxide (2) The amount of aluminum hydroxide is 0 with respect to sodium carbonate decahydrate.
．． The heat storage material according to claim 1, characterized in that the content is 0.05% by weight or more.