JPS58120093A - Composition of heat accumulating agent - Google Patents

Abstract

PURPOSE:To prevent supercooling and increase a heat accumulating density by a method wherein the titled agent is constituted by the inorganic hydrate of alkaline metal or the inorganic hydrate of alkaline earth metal and boric acid as well as inorganic anhydrous salt of alkaline earth metal. CONSTITUTION:The mixture of calcium chloride.6H2O; CaCl2.6H2O and magnesium chloride.6H2O; MgCl2.6H2O, as the inorganic hydrate of the alkaline metal or the alkaline earth metal is added with one to two kinds of boric acid H2BO3 and strontium chloride SrCl2, barium hydroxide Ba(OH)2 or barium fluoride BaF2, as the inorganic anhydrate of alkaline earth metal, in accordance with necessity. According to this adding, the supercooling may be prevented and the heat accumulating density alpha may be increased.

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 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 deliverable substances cause a small temperature drop in the heat storage agent due to heat dissipation, and the phase change latent heat such as melting generally Since it is large, it has the advantage that the heat storage device can be made more compact.

The present invention relates to a technology for storing heat using this latent heat of fusion, and in particular to a technology for modifying an inorganic salt hydrate of an alkali metal or alkaline earth metal so that it is suitable for use as a heat storage agent.

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

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, even with the above proposal, there was still room for improvement. Therefore, the present inventors have conducted extensive research into a heat storage agent composition that further prevents the supercooling phenomenon and has a large amount of effective latent heat per unit weight, and as a result, has completed the present invention.

That is, the present invention is a heat storage agent composition comprising an alkali metal inorganic salt hydrate or an alkaline earth metal inorganic salt hydrate, and boric acid and an alkaline earth metal inorganic salt anhydride. .

In the present invention, the inorganic salt hydrates of alkali metals or alkaline earth metals include lithium nitrate trihydrate (LiNO2/filtered H2O), sodium chromate 1
0 hydrate (Na Cr0 ・10H20), sodium sulfate decahydrate (Na2S○4 ・10H20)
, sodium carbonate decahydrate (Na2CO3・10H2
0), sodium hydrogen phosphate dodecahydrate (Na2I(PO4・12H20), sodium thiosulfate pentahydrate (N a 2 S 203 ” 5 H2
0), magnesium nitrate filtrate (yg(No3)2.
6H20), magnesium chloride filtrate (Mgc&2.
6H20), calcium chloride hexahydrate (c a c l
! 2.6H20), strontium chloride filtrate (5rC62.6'H20), etc. These may be used alone or in combination of two or more.

The amount of boric acid added varies depending on the type of hydrate, but it is 0.1 wt% or more, preferably 0.5 wt% in the composition.
% or more is preferable. The upper limit of the amount added does not need to be particularly limited in terms of effects, but since adding a large amount will reduce the heat storage density accordingly, it should be 2Qwt% or less, preferably i
A content of up to about 0 wt% is practical.

Examples of anhydrous inorganic salts of alkaline earth metals include strontium chloride (s r c j'2 ), strontium fluoride (s r F2 ), and strontium hydroxide (S
r(OH)2), barium chloride (B a Cl 2 )
, barium fluoride (BaF2), barium hydroxide (Ba
(OH)2), magnesium chloride (Mgcff2), magnesium fluoride (MgF2), magnesium hydroxide (M
g(OH)2), calcium chloride (Ca C(12),
Calcium fluoride (CaF2), calcium hydroxide (Ca
(OH)2) etc. Among these, particularly preferred are strontium chloride, barium fluoride, and barium hydroxide. One or more of these compounds may be selected and used as required. The amount added is 1 in the composition.
If the amount added is less than 0.5%, which is 1 Qwt% to 1Qwt%, preferably 5 to 5wt%, the effect of improving supercooling prevention will be small, and if it exceeds 5%, the heat storage density will decrease, which is not preferable.

Further, other additives may be added to the heat storage agent composition of the present invention as necessary.

Example 1 A mixture of 80 parts by weight of calcium chloride filtrate and 20 parts by weight of magnesium chloride filtrate was added with 2% by weight of strontium chloride and 2% by weight of boric acid (Log) in a glass cylinder. After sealing it in a bottle and heating it to 40°C,
A cylindrical bottle (40°C) containing 10g of water was placed in an insulated box containing 100cc of cold water adjusted to 5°C and the water temperature was measured after 30 minutes. The water temperature was measured 30 minutes after the water was placed in the insulation box (blank test), and a value α proportional to the heat storage density of the heat storage agent was determined from the difference in water temperature between the two.

T1 Water temperature of the blank T2: The water temperature results of the heat storage insulation box are shown in Table 1 0 Comparative Examples 1 to 6 and Examples 2 to 4 Except for the composition of the heat storage agent composition shown in Table 1,
Table 1 shows the results obtained in the same manner as in Comparative Example 1.

Claims (1)

[Claims] (1) A heat storage agent composition comprising an alkali metal inorganic salt hydrate or an alkaline earth metal inorganic salt hydrate, and boric acid and an alkaline earth metal inorganic salt anhydride.