JPS6071681A - Heat storage material composition - Google Patents

Abstract

PURPOSE:To provide a heat storage material composition resistant to the lowering of the quantity of the stored heat by the repetition of melting and freezing, from easily available raw materials, by compounding sodium sulfate decahydrate with hydrated aluminum silicate at a specific ratio. CONSTITUTION:The objective heat storage material composition is produced by compound (A) 100pts.wt. of sodium sulfate decahydrate with (B) 1-20pts.wt. (preferably 4-10pts.wt.) of hydrated aluminum silicate, and if necessary (C) a melting point modifier composed of a eutectic mixture of potassium chloride, aluminum chloride, etc. and (D) a crystal habit modifier composed of preferably sodium laurate, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to (sodium bicarbonate decahydrate (Na2SO
The present invention relates to a technique for preventing a decrease in the latent heat storage area due to repeated melting and solidification in a latent heat storage material composition containing 17G-17G-solidification as a main component.

Conventionally, Naz80m ・1 oH, o has a latent heat of fusion of 5
Since it has a large Q kcal /Kf and its melting point can be easily lowered, it is attracting attention as an extremely suitable heat storage material for use in combination with heat pumps, solar collectors, etc., for example.

However, there are two problems when using Na2SO4.101420 as a heat storage material. One of them is that when the melt is cooled, it is supercooled at a temperature significantly lower than the melting point. This supercooling phenomenon is a fatal drawback for heat storage materials because when heat is dissipated, the temperature drops as a liquid without releasing the latent heat of fusion during phase change.As a means to prevent this supercooling phenomenon, As a nucleating substance, sodium tetraborate decahydrate (Na2B407 ・10H20) fr,
U.S. Patent No. 2,667,664 shows that the problem can be solved by adding
The composition of the present invention as disclosed in the specification of the present invention is also based on the premise that Na2B4O7.10H20 or the like is used to prevent supercooling.

Another problem is that the melting properties of Na2SO4.1oH,O are anharmonic. That is, N a 2 S O4
・10 H2O mixes with Na2SO4 saturated solution and N when melted.
Separates into two solid phases of a2S04, Na2SO4
Since the solid is denser than the solution, it settles to the bottom of the container.

When the system separated into two phases is cooled, firstly the precipitated Na
2 Na2SO4 crystals are formed on top of SO4 and act as a barrier, and the remaining Na2SO4 combines with H2O and N
Prevents crystallization of a2SO4+10H,O. There is a problem that the remaining Na2SO4 no longer contributes to the phase change and the amount of latent heat stored is significantly reduced.

In order to solve the above-mentioned problem of phase separation, which is most important in practical use, the molten liquid is turned into a gel, and the solid Na 2 S
A method has been proposed that prevents precipitation of O4 and allows it to be uniformly dispersed and suspended.

Specifically, there are methods of using sawdust, ξulpmethylcellulose, silica gel, various clays, etc. as phase separation prevention materials, and among these methods, JP-A-53-34687 discloses that athano-ξlugite clay is suitable. It is described in. However, in the heat storage material of the composition containing the above-mentioned atta-ξurgite clay, the deterioration of the heat storage amount due to repeated melting and solidification is short-lived; for example, after 300 melting and solidification cycles, the heat storage amount has already reached approximately 30 There are problems such as the kcal / drop to 9. Furthermore, since attapulgite clay is an imported product, there is also the problem that it is difficult to obtain. As mentioned above, there are many problems in preventing the phase separation phenomenon of Na2SO4.10)120, and for practical use, there is a need for a heat storage material composition that is easy to obtain and has reduced deterioration in heat storage amount. There is.

The present invention was made in view of the current situation, and its purpose is to prevent phase separation using an easily available gelling material, to utilize the latent heat of fusion more effectively, and to prevent repeated melting and solidification. It has a small capacity to provide sufficient heat storage capacity.

The above purpose is to prepare a latent heat storage material composition containing Na2'SOa.101 (20) as a main component.
This can be easily achieved by using a composition containing 1 to 20 parts by weight of hydrated aluminum silicate to 120,100 parts by weight.

The main feature of the present invention is the use of hydrated silicon-induced aluminum as a phase separation preventing material.

N a 2 S O4・10 H□0 to hydrated silica l”1
When M aluminum is added in a small amount, it is significantly hydrated to form a stable gel, which prevents sedimentation of Na2SO4.IOH,O particles and plays a role in preventing phase separation, and 1 part or more is required.

If the sub-addition exceeds 20 parts by weight per 100 parts by weight of Na2SO4"10 I20, the amount of latent heat per weight decreases, and the solution viscosity becomes high, making stirring and preparation difficult.

Therefore, in the heat storage material composition of the present invention, it is necessary to have 1 to 20 parts by weight of hydrated aluminum silicate, and from the viewpoint of phase separation prevention effect and heat storage amount per unit weight, it is necessary to have 4 to 20 parts by weight of hydrated aluminum silicate.
It is desirable to select 10 parts by weight.

Irrigation aluminum silicate is generally known as At
It is expressed as 2Si401o(OH)2-nH2O,
Typically, it is a reprinted product from Shiraishi Kozu Co., Ltd., which is easily available under the trade name Osmos N.

The heat storage material composition of the present invention may include known melting point adjusting materials, such as
Eutectic compounds of potassium chloride, aluminum chloride, sodium chloride, potassium nitrate, etc. can also be used as phase separation preventive materials. It is also possible to use crystal habit modifiers, such as sodium hexamethaline, sodium oleate, sodium laurate, etc., added to the crystal, and the combination with sodium laurate is particularly effective.

The details will be clarified below with reference to the working pH and comparative examples.

Examples, Comparative Examples-1 To 100 parts by weight of Na 2804 10 I20, 3 parts by weight of Na2B4O7''10) I20 and 1 and 7.20 parts of hydrated aluminum citrate were added to 3 types. The sample L1 was marked with ■■■.

Separately, as samples, the above-mentioned one without hydrated aluminum silicate, and the one with 7 p+, , 'LH (parts added) in place of hydrated aluminum silicate. The 4'A numbers are marked ■ and ■.

Measurement of initial latent heat values and melting of these five types of samples -
The heat storage amount was measured for 100, 200, and 300 cycles of solidification, 7 divided by 71, and the values are shown in Table 1.

Incidentally, the calorific value was measured using a differential heat Xi-meter.

One cycle of the melting process described above was performed from 60° C. (complete melting) to 0° C. (complete solidifying), and the evaluation was carried out for 6 hours per cycle.

From Table-1, the following song is clear.

The decrease in 7'tT heat after 300 cycles from the initial value is 7 for sample number ■, 3 for ■, 2 for ■, 45 for ■, and 11 for ■.
It can be seen that the water-use aluminum silicate has a greater effect of preventing phase separation than the aqueous ξurgite clay.

Also, from the comparison between sample numbers ■ and ■, the amount added is 7 parts by weight of Ata/ξ Lugite clay and 20 parts by weight of aluminum silicate.
It has been shown that the initial latent heat amount in parts by weight is almost the same, and that increasing the amount added has the advantage of improving repeat stability.

By having the above-mentioned structure, the present invention provides a heat storage material composition that can utilize the latent heat of fusion more effectively, is easily available, contains a phase ratio of P:1, and has excellent cyclic stability. be able to.

Furthermore, the use of the heat storage material composition of the present invention contributes to the effective use of thermal energy, which will become more important in the future.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] A latent heat storage material composition containing sodium sulfate decahydrate as a main component, which contains 1 to 20 parts by weight of hydrated aluminum silicate per 100 parts by weight of sodium sulfate decahydrate. Heat storage material composition