JPS5823877A - Heat storage material composition - Google Patents

Abstract

PURPOSE:A heat storage material composition, prepared by adding boric acid and a fibrous material to an inorganic salt hydrate of an alkali (earth) metal, and capable of taking out the heat at a given temperature stably for a long term without causing the supercooling and phase separation phenomenon. CONSTITUTION:A heat storage material composition prepared by adding (B) preferably 0.5-10wt%, based on the composition, boric acid, and (C) preferably 30-60vol%, based on the total volume of the components (A) and (B), fibrous material, e.g. glass fibers or polypropylene fibers, to (A) inorganic salt hydrate of an alkali (earth) metal, e.g. sodium sulfate decahydrate or calcium chloride hexahydrate. The surface of the component (C) is preferably treated with a surfactant having an HLB value >=10. USE:Heating of agricultural vinyl greenhouses in combination with solar heat, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat storage agent composition mainly comprising an inorganic salt hydrate of an alkali metal or an alkaline earth metal.

Generally, there are two methods for storing heat: one that utilizes the sensible heat of a substance, and the other that utilizes latent heat. A typical example of a method that uses sensible heat is one that uses water or crushed stone, but this method requires a considerably large capacity and weight of the heat storage device, and the temperature of the heat storage agent itself increases as the heat is released. There is a drawback that it decreases. On the other hand, methods that utilize phase change latent heat such as melting generated by inorganic salt hydrates and organic crystalline substances cause a small temperature drop in the heat storage agent due to heat release, and phase change latent heat such as melting is common. This invention has the advantage of being able to make the heat storage device more compact.The present invention is a technology that stores heat by utilizing this latent heat of fusion, and in particular uses an inorganic salt hydrate of an alkali metal or alkaline earth metal as a heat storage agent.・This relates to technology for modifying materials to make them suitable for use.

Originally, when an inorganic salt hydrate is used as a heat storage agent, a supercooling phenomenon occurs in which it does not solidify (crystallize) and does not radiate heat even after the original phase change temperature has passed when the temperature is gradually lowered from the molten state. At the same time, crystallization of insoluble substances occurs during melting, and as the melting-solidification cycle is repeated, the amount of insoluble substances continues to increase, causing problems such as a phase separation phenomenon.

The present inventors have already invented a method for preventing supercooling phenomena and phase separation phenomena, and proposed the invention in Japanese Patent Application No. 56-24941. That is, the gist of the above proposal is to add boric acid to an inorganic salt hydrate of an alkali metal or an alkaline earth metal. However, this proposal also has the problem that phase separation gradually occurs when heat cycles of melting and solidification are repeated over a long period of time. The inventors
As a result of extensive research in order to improve the above-mentioned problems, we have arrived at the present invention.

That is, the present invention is a heat storage agent composition prepared by adding boric acid and a fibrous substance to an inorganic salt hydrate of an alkali metal or an alkaline earth metal.

In the present invention, the inorganic salt hydrate of alkali metal or alkaline earth metal includes lithium mononitrate trihydrate (ztN
o3-xa2o), sodium chromate monohydrate (N
jl 20 r O4” 10 H20)% Sodium sulfate monohydrate (Na2so4-tOH2o), Sodium carbonate monohydrate CM&2003-10H20),
Sodium hydrogen phosphate dodecahydrate (ya2apo4-1
2H20), sodium thiosulfate pentahydrate (N8282
0g'5H20), magnesium nitrate hexahydrate (wgc
yo, )2-bH2o), magnesium chloride hexahydrate (MgO1!2.6H20), calcium chloride hexahydrate (cao112.6H20), and the like.

The amount of boric acid added varies depending on the type of hydrate, but it is Q in the composition, 1 wt% or more, preferably 0.5 wt%.
A range of 1 or more is preferred. The upper limit of the amount added does not need to be particularly limited in terms of effectiveness, but since adding a large amount will reduce the heat storage density accordingly, it should be less than 2 Qwt, preferably 1
A content of up to about 0 wt% is practical.

Fibrous substances include vegetable fibers such as cotton and flax, wool,
Animal fibers such as silk thread and mohair, glass fibers, metal fibers, rock fibers, recycled fibers such as rayon and acetate, nylon, vinylon, and synthetic fibers such as polyethylene fibers and polypropylene fibers are used. Among these, inorganic fibers such as glass fibers, metal fibers, and rock fibers, which are difficult to biodegrade and are stable, and synthetic fibers such as nylon, vinylon, polyethylene fibers, and polypropylene fibers are preferred. The amount of the fibrous substance added varies depending on the type of hydrate, but it is between 10 and 1 of the total amount of the inorganic salt hydrate and boric acid.
00vol%s, preferably in the range of 30 to 60vol%. When the amount added exceeds 100 vol 1%, the heat storage density decreases, and when it is less than 10 vol 1 %, the effect of improving the phase separation phenomenon is small. Further, the fibrous substance may be added to the composition in any form such as a fiber as it is or a woven fabric or nonwoven fabric using the above-mentioned fiber.

In the heat storage agent composition of the present invention, a sufficient effect of preventing the phase separation phenomenon can be obtained even if the above-mentioned fibrous material is simply added, but when the fibrous material is surface-treated with a surfactant, a small amount of Addition is sufficient to prevent phase separation phenomenon.

This is preferable because it has a distortion effect. The surfactant mentioned here is preferably I (LB value is 10 or more, more preferably 13
Methods for surface treating a fibrous material with the surfactant include a method in which the surfactant is sprayed onto the fibrous material, a method in which the fibrous material is immersed in a surfactant solution, and the like.

As mentioned above, the heat storage agent composition of the present invention is produced by adding boric acid and a fibrous substance to an inorganic salt hydrate of an alkali metal or alkaline earth metal, thereby eliminating or reducing the supercooling phenomenon and phase separation phenomenon. The purpose of the present invention is to provide a heat storage agent composition that can stably extract heat at a predetermined temperature over a long period of time. It goes without saying that even if a fibrous material consisting of at least two of the above fibrous material groups is added, supercooling and phase separation phenomena will not occur. Further, other additives may be added to these heat storage agent compositions as desired.

The heat storage agent composition of the present invention can be used in agricultural equipment such as heating agricultural greenhouses and various other heat storage applications by combining it with solar heat or other heat sources. Examples of the present invention are shown below.

Example 1 1 wt% of boric acid to calci-rum chloride hexahydrate,
Glass fiber added and mixed at 5 Q vo1% (1a
g) was sealed in a glass cylindrical bottle, and the operation of leaving it in a 40° C. high temperature bath for 1 hour and then leaving it in a 5° C. cold bath for 1 hour (heat cycle operation) was repeated 100 times. At this time, the behavior of calcium chloride hexahydrate in the cylindrical bottle was visually judged as follows.・Those that do not cause phase separation phenomenon/supercooling phenomenon・○Those that cause supercooling phenomenon・
・・・・・・△Things that cause phase separation phenomenon/supercooling phenomenon・・
...×100cc of cold water adjusted to 5°C from a cylindrical bottle (40°C) that has been heat cycled 100 times
The water temperature was measured after 30 minutes. Also, a cylindrical bottle (40℃) containing 10g of water was heated at the same 5℃.
The water temperature was measured 30 minutes after the sample was placed in an insulated tank containing cold water (blank test), and a value a proportional to the heat storage density of the heat storage agent was determined from the difference in water temperature between the two.

T, Ni blank water temperature T2: Water temperature of heat storage tank containing heat storage agent The results are shown in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that a polypropylene fiber nonwoven fabric (Toughnel ■: Mitsui Petrochemical Industries KK) was used instead of glass fiber. The results are shown in Table 1.

Example 3 Surfactant (Actinol L-1) instead of glass fiber
A polypropylene fiber nonwoven fabric (Toughnel [F] Doki Matsu) U3O: Mitsui Petrochemical Industries KK) surface-treated with s (HLBls, 6)i Matsumoto Yushi Seiyaku KK) is used.

The same procedure as in Example 1 was carried out except for this. The results are shown in Table 1.

Example 4 5 wt% boric acid to sodium sulfate decahydrate,
The same procedure as in Example 1 was carried out using a polypropylene fiber nonwoven fabric mixed with 5QVO 1%. The results are shown in Table 1.

Comparative example 1 The same procedure as in Example 1 was carried out except that boric acid was not added.

The results are shown in Table 1.

Comparative Example 2 The same procedure as Example 2 was carried out except that boric acid was not added. The results are shown in Table 1.

Comparative Example 5 The same procedure as in Example 1 was carried out except that boric acid and glass fiber were not added. The results are shown in Table 1.

Table 1

Claims (2)

[Claims] (1) A heat storage agent composition prepared by adding boric acid and a fibrous substance to an inorganic salt hydrate of an alkali metal or alkaline earth metal. (2) The heat storage agent composition according to claim 1, wherein the fibrous material is one that has been surface-treated with a surfactant.