JPS5827301B2 - Supercooling prevention material and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a supercooling prevention material for a heat storage material using latent heat of fusion.

For example, in order to use a hydrate such as Na2SO4.10H20 as a heat storage material and effectively extract its latent heat during solidification, it is necessary to melt and solidify smoothly.

For this reason, a small amount of a supercooling prevention base material is usually added to the heat storage material.

Here, the supercooling prevention base material is a material that is present in the heat storage material and immediately exerts a heterogeneous nucleation effect when the heat storage material that is in a liquid state without melting away is cooled even slightly below its melting point. It has the effect of generating fine solids of the heat storage material on its surface and promoting solidification.

Therefore, a supercooling prevention base material is added to the heat storage material that uses the latent heat of fusion, which tends to become supercooled, but it does not mix well with the liquid heat storage material at first, so the supercooling prevention function may not work. many.

There are also heat storage materials containing such supercooling prevention substrates.

Once solidified by some method, a solid phase of the heat storage material will precipitate on the surface of the supercooling prevention base material, and the supercooling prevention base material and heat storage material will become compatible, and will become stable from then on. Repeat melting and solidification.

For example, NaCH3COO・3H20 is used as a heat storage material.
N a 4 P 207.10 as a base material for preventing supercooling
In cases where H20 is used, supercooling is often difficult to break during the first solidification, and the mixture is often cooled to room temperature.

N a CHs COO'3H2 in this supercooled state
A mixture of 0 and Na4P2O7.10H20 will also stably repeat melting and solidification once solidified by some method.

Therefore, when such a heat storage material and a base material for preventing supercooling are actually stored and used in a heat storage tank, the mixture of the heat storage material and the base material for preventing supercooling is heated once to the temperature at which the heat storage material melts.
Cool it again to see if the supercooling can be broken successfully, and if the supercooling cannot be broken, you must break the supercooling in some way and make it solidify.

This requires a lot of time and effort, and is not desirable from a practical standpoint.

Recently, when using heat storage materials in air conditioning equipment,
It has become necessary to freely control coagulation behavior.

Therefore, single crystals are being used as a base material for preventing supercooling.

However, single crystals do not have many parts on the crystal surface that can cause heterogeneous nucleation such as dislocations, and the surface that is exposed to the surface is limited, so the supercooling prevention function is It is usually weaker than that of .

The present invention solves the above problems by coating at least a portion of the surface of the supercooling prevention substrate with a heat storage material that utilizes latent heat of fusion.

That is, by using this supercooling prevention material, the heat storage material using the latent heat of fusion is reliably solidified from the first time with almost no supercooling.

Furthermore, since a single crystal is used as the base material for preventing supercooling, it is possible to provide a material for preventing supercooling that makes it possible to control the solidification behavior of the heat storage material.

Heat storage materials for which the supercooling prevention material of the present invention is particularly effective include inorganic hydrates that have a large latent heat of fusion but are subject to large supercooling and therefore require a suitable supercooling prevention substrate.

In order to manufacture such a supercooling prevention material, in the present invention, a mixture of a heat storage material and a supercooling prevention base material is heated to a temperature higher than the melting temperature of the heat storage material, and then the supercooling prevention base material is heated to a temperature equal to or higher than the melting temperature of the heat storage material. By taking the heat storage material out of the melt and cooling it, the heat storage material is solidified and adhered to the surface of the supercooling prevention base material.

About the present invention NaCH3α powder/3H20 as a heat storage material
(melting point 58℃), Na4P2O as a base material to prevent supercooling
The case where 7.10H20 is used will be explained as an example.

100 parts by weight of NaCH3COO+:3I(2o) was placed in a glass container and the container was placed in a water bath and heated to 80'C to melt all of the NaCH3COO''3H20.

And in it there are 50 crystals of Na4P20710H20.
Parts by weight were added and mixed.

Crystals of Na4P207.■0H20 were deposited at the bottom of the container.

After that, using a suitable net etc., Na4P2O7・10H20
The crystal grains were scooped out.

At that time, N on the Na4P2O7・10H20 crystal surface
a CH3COO” 3H20 melt was attached.

If you leave it for a while at room temperature, the NaCH on the surface
3COO・3H20 solidifies and becomes Na4P2O7”10
A supercooling prevention material in which the H20 crystal surface was covered with NaCH3COO.3H20 crystals was obtained.

The operation of the supercooling prevention material of the present invention was carried out in the same manner as in the above-mentioned manufacturing method.
The case where 0 is used will be explained.

The supercooling prevention material o and i obtained by the above manufacturing method are
Mix with 100 parts by weight of aCH3COO・3H20, 70
Heated to ℃ to melt NaCH3COO.3H20.

By the way, the inside of this supercooling prevention material is Na4P2O7'
10H20 crystal with external Naa-(3CO0・3H2
0, so naturally the external N a CH3COO'3
It is believed that H20 melts at the same time.

And when cooled again, Na4P2O7・10H20
It is thought that heterogeneous nucleation occurs on the crystal surface and prevents supercooling.

By the way, the crystal of Na4P20710H20 used here has once formed a crystal of Na CH3COO"3H20 on the surface, so the total heat of NaCHCO0.3H
Na4P2 that has never formed 20 crystals on the particle surface
It has a far superior supercooling prevention function compared to O7/10H20.

Although the cause of this is not clear to date, on the surface of the Na4p2o7 + 10H20 particles that once formed NaCH3COO・3H20 crystals on the surface,
Even after NaCH3α)O-3H20 has melted again, some trace remains, which effectively converts NaCH3CO
It is thought that it acts on the crystallization of O.3H20.

By the way, the supercooling prevention material of the present invention has the feature that it reliably has a supercooling prevention function from the first use. It also has the feature that it is an excellent supercooling prevention material with an excellent supercooling prevention function, and it is possible to control the solidification behavior of the heat storage material by adjusting the installation position of the supercooling prevention material in the heat storage device. .

In addition, CaC1□・6 is used as a heat storage material using latent heat of fusion.
H,20, and NaCl as a base material for preventing supercooling.
, KCl, etc., supercooling does not easily break during the first solidification.

However, NaC1 obtained by the production method of the present invention
Or Ca
When a supercooling prevention material coated with Cl 2 .6H20 crystals is used, supercooling is reliably broken from the first time, and an effective supercooling prevention effect can be obtained thereafter.

Other heat storage materials include Na2S2O3・5H20 and Na2H.
By applying the present invention to an inorganic hydrate such as PO4.12H20, which has a large latent heat of fusion but is highly supercooled, and a base material for preventing supercooling, supercooling can be ensured from the first time. By using a single crystal as the base material to prevent tearing and supercooling, it has become possible to control the solidification behavior by devising the installation position of the supercooling prevention material.

The present invention will be explained in detail below.

Example 1 100 parts by weight of NaCH3COO.3H20 was heated to 70°C to completely melt it.

Two parts by weight of a single crystal of Na4P2O7.10H20 was put into the melt of NaCH3C00.3H20 for 1 minute, and then taken out and left at room temperature.

As a result, Na CHsC00 3H20 attached to the surface of the Na4P2O7 10H20 single crystal solidifies,
A supercooling prevention material was obtained.

2.5 parts by weight of this supercooling prevention material was added to NaCH3COO.3
The mixture was placed in 1,000 parts by weight of H20, heated and cooled repeatedly, and the melting and solidification behavior was observed.

NaCH3COO.3H20 steadily crystallized from the surface of the supercooling prevention material with almost no supercooling from the first solidification, and exhibited a remarkable supercooling prevention function.

Furthermore, it was confirmed that the solidification behavior could be sufficiently controlled by adjusting the location of the supercooling prevention material in the heat storage device.

Example 2 100 parts by weight of CaC1□.6H20 was heated to 40°C to completely melt it.

A single crystal containing 2 parts by weight of NaCl was placed in the CaCl2.6H20 melt for 30 seconds, and then taken out and placed in a refrigerator at 5°C.
2.6H20 was solidified to obtain a supercooling prevention material.

5 parts by weight of this supercooling prevention material was added to CaCl2" 6H20
The mixture was placed in 100 parts by weight and heated and cooled repeatedly to observe melting and solidification behavior.

CaCl2.6H20 was reliably crystallized from the surface of the supercooling prevention material with almost no supercooling from the first solidification, and exhibited a remarkable supercooling prevention function.

Furthermore, it was confirmed that the solidification behavior could be sufficiently controlled by adjusting the location of the supercooling prevention material in the heat storage device.

As mentioned above, the supercooling prevention material of the present invention reliably prevents supercooling from the first cooling of each predetermined heat storage body, and thereafter stably prevents supercooling from occurring. Single crystal, which has the characteristic of solidifying heat storage materials and was previously thought to have an inferior supercooling prevention function, now has the same or better supercooling prevention function than pulverized fine powder, and as a result, , it has the feature that it is possible to control the solidification of the heat storage material.

Moreover, it goes without saying that the combination of the heat storage material and the supercooling prevention base material that can be applied to the supercooling prevention material of the present invention is not limited to the examples described above.

The supercooling prevention material of the present invention has a structure in which the surface of the supercooling prevention base material is coated with a heat storage material, and since there are no particular restrictions on the supercooling prevention base material and the heat storage material, it can be used in a wide temperature range. Since it can be applied to the prevention of supercooling of latent heat type heat storage materials and the manufacturing method thereof is easy, it will have a great influence on the practical application of heat storage systems to which latent heat type heat storage materials are applied.

According to the manufacturing method of the present invention, the above-mentioned supercooling prevention material can be easily obtained.

Claims (1)

[Scope of Claims] 1. A supercooling prevention material, characterized in that at least a portion of the surface of a supercooling prevention base material is coated with a heat storage material that utilizes latent heat of fusion. 2 Sodium acetate trihydrate (N a C
Hs COo ・3H20) and sodium pyrophosphate decahydrate (Na4P20) as a base material for preventing supercooling.
7+10H20), respectively. The supercooling prevention material according to claim 1. 3. The temperature of a mixture of a heat storage material that uses latent heat of fusion and a supercooling prevention base material is set to be higher than the melting temperature of the heat storage material, and the supercooling prevention base material is taken out from the solution of the heat storage material and cooled. A method for producing a supercooling prevention material, comprising solidifying and adhering the heat storage material to the surface of the supercooling prevention substrate.