JPS6187774A - Thermal energy storage material composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. whose solidifying point can be controlled over a wide range and which can prevent supercooling, containing CaCl2.6H2O, a solidifying point modifier composed of a specified amount of ZnCl2 and a nucleation accelerator composed of CaHPO4.2H2O and BaS. CONSTITUTION:CaCl2.6H2O, nor more than 40wt% (based on the total amount of compsn.; the same shall apply hereinbelow) ZnCl2 as a solidifying agent, a nucleation accelerator composed of 0.005-10wt% CaHPO4 and 0.005-10wt% BaS, and optionally an appropriate amount of a thickener (e.g. 5wt% glycerol) are blended together to obtain the titled compsn. in which latent heat-utilizing temp. can be controlled over a temp. range of 30-10 deg.C and supercooling can be inhibited to 2 deg.C or below.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a heat storage material composition containing calcium chloride hexahydrate as a main component, and in particular, the freezing point can be arbitrarily adjusted over a wide range, and the This relates to technology that prevents overcooling and improves the performance of heat storage materials.

[Conventional technology]

Calcium chloride hexahydrate has a large solidification-melting characteristic unique to hydrates, and its freezing point is around room temperature (approximately 30°C), so it is useful for greenhouse horticulture, cultivation greenhouses, home heating, and chemical heat pumps. Furthermore, it is beginning to be widely put into practical use in heat storage tanks for saw 2, industrial waste heat recovery equipment, etc. However, when using calcium chloride hexahydrate alone, the latent heat generation temperature is specific to one point, which is its freezing point (and melting point) of approximately 30°C, so research is also underway to improve the latent heat generation temperature so that it can be adjusted according to the usage environment. It is being This type of technology involves adding an appropriate amount of a freezing point regulator (for example, calcium bromide hexahydrate, ferric chloride hexahydrate, cobalt chloride hexahydrate, cupric chloride dihydrate, There is a method of adjusting the freezing point to an arbitrary value by adding magnesium chloride hexahydrate (magnesium chloride hexahydrate, etc.).

On the other hand, when calcium chloride hexahydrate is heated from a temperature lower than its freezing point, it becomes liquid while absorbing latent heat of fusion at the freezing point. This phase change progresses almost according to theory, so there is no problem; however, the following problems arise regarding the reverse phase change. In other words, if you lower the temperature from the high temperature side of the freezing point, theoretically it should undergo a phase change and become solid at the freezing point temperature, but in reality, a supercooling phenomenon occurs (the freezing point). Since it may remain in a liquid state even when cooled to a low temperature of 20 to 10 degrees Celsius, this becomes a major obstacle when utilizing the latent heat of solidification. As a method for preventing such supercooling, a method is known in which a coagulation nucleation accelerator is blended into calcium chloride hexahydrate.
Nucleation accelerators such as H)2.8H,0 and Ba(OR)28H20 have been used and have achieved certain results.

[Problem that the invention seeks to solve]

However, conventionally known freezing point regulators are
The freezing point can be adjusted over a wide range with a small addition amount,
It cannot be said that it fully satisfies the required properties such as "and does not reduce the amount of latent heat," and conventional nucleation accelerators are expensive, so it is necessary to expand the use of this type of heat storage material composition. This is a big obstacle to getting there. Under these circumstances, the present invention seeks to find a new freezing point regulator and nucleation promoter that have the required properties, and provides a heat storage material composition with excellent performance and economy.

[Means to solve the problem]

In the heat storage material composition of the present invention, which contains calcium chloride hexahydrate as a main component, zinc chloride of 40% or less (weight %: the same hereinafter) is contained in the entire composition as a freezing point regulator, and also promotes nucleation. The gist is that it contains calcium monohydrogen phosphate and barium sulfide as agents.

[Effect]

The first feature of the present invention is that zinc chloride is selected as the freezing point regulator for calcium chloride hexahydrate, thereby making it possible to arbitrarily adjust the freezing point with a relatively small amount of freezing point regulator. . That is, FIG. 1 shows the zinc chloride content [wt% of the total composition (the same applies hereinafter) when zinc chloride is blended as a freezing point regulator into a heat storage material composition containing calcium chloride hexahydrate as a main component. )] and freezing point, and also includes experimental results using ferric chloride hexahydrate and calcium bromide hexahydrate, which are known representative freezing point depressants. are doing. As is clear from this figure, the gradient of descent of the freezing point of ferric chloride hexahydrate as the content increases is small, and a considerably large amount must be contained in order to lower the latent heat generation temperature. Moreover, in this two-component composition, about 6
It shows the lowest freezing point (10°C) only when 0% ferric chloride hexahydrate is blended. This tendency is almost the same for cupric chloride dihydrate, magnesium chloride hexahydrate, cobalt chloride hexahydrate, and the like. On the other hand, calcium bromide hexahydrate has a large downward slope of the freezing point as the content increases, and the freezing point can be shifted to the lower temperature side even with a relatively small content. The lowest freezing point is reached when the content is 50%, but the temperature is at most 15~15%.
It is not possible to set the latent heat generation temperature to a low temperature below 15°C. On the other hand, when zinc chloride is added, the gradient of decrease in the freezing point due to the increase in the content is considerably large, and the lowest freezing point obtained when the content is about 35 to 40% falls to about 10°C. That is, by adjusting the content of zinc chloride within a range of 40% or less, the latent heat utilization temperature can be set to any temperature within a wide range of about 30°C to about 10°C.

In this way, the freezing point can be arbitrarily adjusted by incorporating an appropriate amount of zinc chloride into calcium chloride hexahydrate. However, the supercooling phenomenon during temperature drop remains unresolved. Nucleation accelerators for preventing supercooling include <5 as described above.
rC1t・6H20, 5r(OH)z・8H20, etc. are known, and these exhibit the same supercooling prevention effect on calcium chloride hexahydrate-zinc chloride based heat storage material compositions, but the above-mentioned The disadvantage is that it is expensive. Therefore, as a result of conducting research in search of an inexpensive nucleation accelerator that can effectively prevent supercooling for the above-mentioned two-component heat storage material composition, we found that phosphoric acid It has been confirmed that when calcium monohydrogen dihydrate and barium sulfide are used together, the effect of preventing supercooling is comparable to that of nucleation promoters such as 5rC12.6H20. In order to effectively exhibit these effects, the preferred content [also the content in the total amount of the composition, calcium monohydrogen phosphate dihydrate (Ca HP 04 ・2 H
zO) is 0.005 to 10, preferably 0.5 to 10
5), barium sulfide (BaS) 0.005-10%
(The preferred setting is 0.01 to 10°C.) By using both in this range, supercooling can be suppressed to about 2°C or less. If the content is less than the above range, the supercooling prevention effect will not be sufficiently exhibited, while if it exceeds the above range, the absolute amount of calcium chloride hexahydrate will decrease, resulting in a lack of heat storage.

As mentioned above, the heat storage material composition of the present invention has calcium chloride 6
The main component is aqueous salt, which also contains zinc chloride as a freezing point regulator, and calcium monohydrogen phosphate and barium sulfide as nucleation promoters to prevent supercooling, as well as appropriate amounts as necessary. A thickener may also be added. That is, the thickener maintains the nucleation accelerator etc. in a stable dispersion state in the liquid heat storage material composition, and also maintains the solid state.
Glycerin is a typical thickener that acts to prevent phase separation caused by differences in specific gravity of liquids.

Further, it is also possible to use sodium dihydrogen phosphate, disodium hydrogen phosphate, etc. together with the above-mentioned nucleation promoter.

〔Example〕

Hereinafter, actual formulation examples of the heat storage material composition according to the present invention and their characteristics will be shown.

(1) Heat storage material composition having a freezing point of about 20° C. Heat release curves for typical heat storage material compositions shown in Table 1 are shown in FIG. 2. For reference, FIG. 2 also shows the heat release curve of the sample without the addition of a nucleation accelerator.

As is clear from FIG. 2, a significant supercooling phenomenon is observed when no nucleation accelerator is added, whereas the supercooling phenomenon is hardly observed with the heat storage material composition of the present invention.

(2) In the basic formulation of the invention example shown in Table 2, B
The results shown in Table 3 were obtained when the supercooling temperature ('C) and heat storage performance during repeated use were investigated when the aS blending ratio was variously changed.

The preferred blending ratio flo of BaS derived from the results in Table 2 and Table 3,
01-10%.

(3) Table 4 illustrates other heat storage material compositions according to the present invention, and their heat release curves are as shown in FIG. 3.

As is clear from this experimental result, in the present invention, Ca
HP 04 ” Na2HP with 2HtO and BaS
It is also possible to use O4.12H20, NaH2PO4.2H, and Ot- in combination.

〔Effect of the invention〕

The present invention is constructed as described above, and provides a heat storage material composition which can adjust the latent heat generation temperature to any point within a wide range, can significantly suppress the supercooling phenomenon, and has excellent cyclic stability. I was able to provide it. Furthermore, the freezing point depressant and nucleation promoter used can be obtained at a lower cost than conventional agents, making it possible to provide a heat storage material composition with excellent performance at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a graph 27 showing the relationship between the blending ratio of the freezing point regulator and the freezing point, and FIG. 2.3 is a graph showing the heat release curve of the heat storage material composition.

Claims (1)

[Claims] In a heat storage material composition containing calcium chloride hexahydrate as a main component, not more than 40% (weight %: the same applies hereinafter) of zinc chloride is contained in the entire composition as a freezing point regulator, and phosphoric acid 1 is contained as a nucleation promoter. A heat storage material composition containing calcium hydrogen and barium sulfide.