JPS5941667B2 - heat storage material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat storage material that utilizes heat of fusion and is suitable for a heat source of a heat pump of an air conditioner.

CaCl2.6H2O has long been attracting attention as a heat storage material because its melting point is 29°C and its heat of fusion is as high as 68.5 cal/cc.Moreover, the melt is almost neutral, it is less corrosive, and it is inexpensive. However, since measures to prevent the supercooling phenomenon have not yet been solved, it has not yet been put into practical use.

The CaCl2.6H20 melt is easily supercooled to 0°C and may not solidify even after several days.According to our knowledge, the reason for this is that the water requires some sort of rearrangement during solidification. This is thought to be largely due to the hydration phenomenon of (Caf) ions. Melting point 3
CaBr2.6H20 at 5° C. also has almost the same tendency as CaCl2.6H2O. Also, CaCl2・6H2O
According to our prior invention, a hydrate mixture system containing CaBr2.6H20 as a main component is useful as a practical heat storage material for air conditioning. That is, CaCl2.6H20-
MgC12・6H2O system (melting point 22-24℃: JP-A-51-43387), CaCl2・6H20-MgBr
2. 6H2O system (melting point 15-18℃: JP-A-51-7
6183), CaCl2.6H2O-CaBr2.6H
20 series (melting point 15-16°C: JP-A-51-128052
)3CaBr2・6H2O-LiBr・2H2O system (
The melting point is 12-14℃: JP-A-52-11455), and these mixed systems are independent of CaCl2.6H20 and C
Although it is easier to break due to supercooling than aBr2/6H20, there is a problem with reliability in practical use. Although it is a well-known fact that supercooling can be broken if a supercooled liquid is injected with its own seed crystal, it is nearly impossible to use such a method in practical use as a heat storage material.

This is because the heat storage tank has a sealed structure to prevent water evaporation, and since the melting point is 29°C, most of the crystals themselves melt and disappear in the summer.
As a result of long research, the inventor of the present invention has found that the compounds listed in Table 1 have an extremely effective effect in preventing supercooling of a mixed heat storage material containing CaCl2.6H2O, CaBr2.6H20, or either of the two as main components. discovered. At present, it is not clear what properties of these compounds are responsible for such supercooling prevention effect. However, it is certain from Table 1 that such an effect cannot be understood from the viewpoint of epitaxial growth in the usual sense (same crystal form, same lattice constant). Because CaCl2・6H20 and CaBr2・6H2
This is because O belongs to the hexagonal system and the crystal form does not match that of the substances in Table 1. So far, supercooling prevention materials have been searched for that are effective at the lowest possible degree of supercooling, but when used for indoor wall heating, for example, it is not always necessary to immediately break supercooling. Not only is this not the case, but in some cases it may be practically preferable to actively supercool to a certain temperature and only exert the supercooling prevention effect when the temperature drops below that temperature.

In order to be able to freely select a supercooling preventive material with a preferable operating temperature range depending on the purpose, it is necessary to search for as many supercooling preventive materials as possible. is sufficient for this purpose. The supercooling prevention effect of the substances listed in Table 1 on CaBr2.6H20 is almost the same as that on CaCl2.6H20, except that the temperature at which supercooling breaks is as shown in Table 1.
The value was several degrees higher than the number given above. In addition, Bas
O4 and SrSiF6 have no supercooling prevention effect.
Examples will be described below. Example 1CaC12
- Add 0.1% by weight of BaHPO4 to 6H20 and melt it, then place it in a heat storage tank and cover the surface with a liquid paraffin layer to prevent moisture evaporation.

During heat dissipation operation, solidification starts at 22℃, and the temperature of the heat storage material immediately becomes 29℃, approximately 68.5ca1/Cc.
The heat of fusion was obtained. Example 2 0.02% by weight of CaSiF6 in CaC12.6H20
After it is added and thawed, it is placed in a heat storage container installed on the wall of the room and sealed tightly.

This material starts to solidify when the indoor temperature drops below 18℃, and the temperature of the heat storage material immediately rises to 29℃, resulting in 65ca1/
The amount of heat dissipated was greater than Cc. Example 3 20 mol% of MgBr2/6H20 was added to CaC12/6H20, and 1% by weight of Bac2O4 was added as a supercooling prevention agent.
Add.

This composition was completely solidified by brine at 11°C;
It released a latent heat of fusion of about 60 cal/Cc between 15 and 17°C. Example 4 CaC12.6H20 and CaBr2.6H20 were mixed in a molar ratio of 1:1, and Ba2p4 was used as a supercooling prevention material.
Add 0.5% by weight O7.

This material started solidifying at 10° C. and released a latent heat of fusion of 50 cal/Cc or more. Example 5 CaBr2.6H20 with 0.1% by weight of BaSiO3 started to solidify at 25°C or higher, the temperature of the heat storage material immediately rose to 33°C or higher, and solidification heat of 40ca1/CC or higher was released.

Claims (1)

[Claims] 1 CaCl_2・6H_2O or CaBr_2・
BaHP is added to the heat storage material containing at least one of 6H_2O.
O_4, Ba(H_2PO_4)_2, Ba_3(PO
_4)_2, Ba_2P_4O_7, BaPO_3, B
aC_2O_4, Ba(BO_2)_2, BaSiO_
3. A heat storage material containing at least one compound selected from the group consisting of CaSiF_6 and BaSiF_6.