JPS617378A - Thermal energy storage material - Google Patents

Abstract

PURPOSE:A thermal energy storage material, obtained by incorporating a system consisting of sodium acetate and water with lithium fluoride in a specific proportion, capable of preventing the supercooling phenomenon of sodium acetate trihydrate, and having high heat resistance, stable heat absorption and release performance and large thermal energy storage capacity. CONSTITUTION:A thermal energy storage material obtained by adding 0.1- 40pts.wt. lithium fluoride as a crystal nucleus forming material for preventing the supercooling in crystallizing the sodium acetate trihydrate to 100pts.wt. system of sodium acetate and water containing the sodium acetate in an amount within 55-73wt% range.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a latent heat storage material mainly composed of sodium acetate trihydrate.

Conventional Structure and Problems Conventionally, sodium cyacetate trihydrate (NaOH5COO'3H20, melting point 68° C.) has a large amount of heat storage and has been seen as a promising heat storage material for heating, for example. However, once NaOHsCOo.3H20 is melted, it is very susceptible to supercooling, so the supercooling does not break unless the molten liquid is cooled to about -20°C. The supercooled state is 1. even when cooled to the freezing point. This is a phenomenon in which the latent heat of fusion is not released and the material is cooled below that temperature, which is a fatal drawback for heat storage materials that utilize molten layers and heat.

In order to solve this problem, NaCH3000.3
Various additives have been proposed to promote the crystallization of H20 (Japanese Patent Laid-Open No. 147580/1983). However, all of these currently proposed crystal nucleation materials have a heat resistance of 8.
If heated below 5℃, but at around 90℃, it will lose its function as a heat storage material in a short period of time (BJ, Q, C
hem, Soc, Jpn, , 57, 561
-563 (1984)). However, current heat storage materials based on sodium acetate trihydrate cannot rapidly store heat using a heat source of 85°C or higher, which has been a major problem in practice.

Purpose of the Invention The present invention provides a heat storage material that prevents the supercooling phenomenon of NaCH3COO/3H20, has high heat resistance, is inexpensive, has stable heat absorption and release performance, and has a large amount of heat storage per unit weight or unit volume. This is what we aim to provide.

Structure of the Invention The characteristics of the present invention are that N a GHB COO
NaCH containing in the range of 66% to 73% by weight
For 100 parts by weight of a system consisting of 3coo and H2O, N
a Lithium fluoride (
r,,tF) in a range of 0.1 parts by weight to 40 parts by weight.

Description of Examples Each sample was prepared using a commercially available special grade reagent to have the composition shown in Table 1. Each sample was heated to NaC
After melting H3COO・3H20 and mixing it thoroughly, and further cooling to solidify NaOH, Coo・3H20,
Using a differential set meal calorimeter, measure the latent heat of fusion of each sample,
Using the results, the amount of latent heat per gram of each sample was calculated.

The amount of latent heat per unit weight thus determined is shown in Table 2.

Table 1 Table 2 Ten samples of each sample were also sealed in plastic containers. 10 containers filled with this heat storage material are heated in a constant temperature chamber for 10 hours, then cooled to 40℃, and the heat resistance of the heat storage material is determined whether NaCH3COO/3H20 crystallizes inside the containers within 2 hours. The gender was evaluated. The upper temperature limit was set as the upper limit temperature at which crystallization of NaCH3COO.3H20 was observed in all 10 samples. Table 2 also shows the heat resistance temperature of each sample determined in this way. However, if each sample is heated above the heat-resistant temperature shown in Table 2, some of the 10 samples will become supercooled without solidifying. For example, in the case of sample 3, when heat treatment was performed at 94° C., 6 out of 10 samples were supercooled.

By the way, the amount of latent heat is 40 cal/e1 or more, and
Samples with a heat resistance temperature of 86°C or higher have a sufficiently large amount of heat storage and a sufficiently high heat resistance temperature, so it is considered that they can be put to practical use as a latent heat storage material capable of rapid heat storage. I marked it with an ○. Others were marked with an X. By the way, as is clear from Table 2, the composition range of this O-marked sample is NaCH3000 containing NaCH, 5COO in the range of 66% to 73% by weight.
For 100 parts by weight of a system consisting of
．． The content ranges from 1 part by weight to 5031 parts by weight.

Sample 19 with the same composition as sample 9 has an inner diameter of 1 oomm and a length of 1
It was stored in a 00ffff cylindrical container and sealed with a stopper equipped with a thermocouple insertion tube. When the container was placed in a water bath and heated and cooled 1000 times between 90°C and 40°C, stable heat storage and heat dissipation characteristics were obtained, and no overall heat deterioration was observed. It was confirmed that the material has sufficient characteristics as a latent heat storage material that can rapidly store heat.

Effects of the Invention As shown in the examples, the heat storage material of the present invention has Na
System 10 consisting of NaCH3000 (!: H2O) containing CHsCOO in the range of 56% to 73% by weight
0.1 parts by weight to 40M of LiF to 034 parts by weight
Since it contains within the range of 1.5 parts, it has high heat resistance and can rapidly store heat. It has become. Therefore, the heat storage material of the present invention can be applied not only to heat storage devices for air conditioning, but also to all fields that utilize heat storage, such as heat storage type heat insulators.

Claims (1)

[Claims] Sodium acetate and water (H
A heat storage material characterized by containing lithium fluoride (LiF) in an amount of 0.1 to 40 parts by weight based on 100 parts by weight of a system consisting of _2O).