JP2003034785A - Method for producing heat storage material composition - Google Patents

Abstract

(57) [Problem] To provide a simple method for producing a heat storage material composition in which supercooling is suppressed in the production of a heat storage material composition using latent heat of sodium acetate trihydrate. SOLUTION: A sodium acetate aqueous solution having a concentration of 52 to 60% by weight is maintained at a temperature higher than its melting point, and a supported crystal is added to the aqueous solution in an amount equal to or higher than a saturation concentration of the supported crystal, and after filling into a container, seeds are added. A method for producing a heat storage material composition, wherein the heat storage material composition is cooled and solidified below the melting point in the presence of crystals. The above production method, wherein the supported crystal is disodium hydrogen phosphate or sodium chloride.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a heat storage material composition for a heat storage device used for heating a building or the like.

[0002]

2. Description of the Related Art A heat storage device which uses a salt hydrate as a heat storage material composition and stores and releases heat by utilizing latent heat in the phase change of solid and liquid has already been put to practical use in the field of floor heating and the like. ing. Sodium acetate 3 among salt hydrates
Hydrosalt has a melting point of 58 ° C. suitable for heating, and has a high heat of fusion of about 60 cal / g, and therefore has attracted attention as a candidate for a heat storage material composition.

However, sodium acetate trihydrate is liable to cause supercooling, which is a phenomenon of keeping a liquid state without solidifying even when cooled to a temperature lower than its melting point, and thus has a problem as a heat storage material composition.
As a method for producing a heat storage material composition in which supercooling is suppressed,
Add anhydrous sodium acetate to disodium hydrogen phosphate, which is a supported crystal having a function of supporting a seed crystal on the surface, and
Press-molded at a pressure of 000 kg / cm ² into a disk,
A method of manufacturing by inserting this disk into a container containing sodium acetate trihydrate and sealing the container is disclosed in Japanese Examined Patent Publication No. S61.
-42957.

Further, in Japanese Patent Laid-Open No. 57-74380, sodium pyrophosphate is added as a supporting crystal to an aqueous solution of sodium acetate trihydrate held at a melting point or higher, sodium pyrophosphate is taken out by filtration and cooled, Although a production method is disclosed in which sodium acetate trihydrate adhering to the surface is solidified and added again to the sodium acetate aqueous solution, a simpler method for preventing supercooling has been demanded.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple method for producing a heat storage material composition in which supercooling is suppressed in the production of the heat storage material composition utilizing the latent heat of sodium acetate trihydrate. To do.

[0006]

Means for Solving the Problems As a result of intensive investigations under these circumstances, the present inventors have found that the concentration is 52 to 60% by weight.
The aqueous solution of sodium acetate of is maintained above its melting point, the supported crystals are added to the aqueous solution in an amount equal to or more than the saturated concentration of the supported crystals, and after filling the container, cooled to below the melting point in the presence of seed crystals. By solidifying, sodium acetate 3
The present inventors have found that a heat storage material composition utilizing latent heat of hydrate can be produced more easily than conventional production methods, and completed the present invention.

That is, according to the present invention, an aqueous sodium acetate solution having a concentration of 52 to 60% by weight is maintained above its melting point, and a supported crystal is added to the aqueous solution in an amount not less than a saturated concentration of the supported crystal, and then added to a container. Provided is a method for producing a heat storage material composition, characterized by cooling to below the melting point and solidifying in the presence of seed crystals after filling. Further, the present invention is a supported crystal,
Disclosed is the above production method, which is disodium hydrogen phosphate or sodium chloride. The present invention also provides the above-mentioned production method, wherein the seed crystal is a crystal formed by crystallization of a part of an aqueous sodium acetate solution. The present invention also provides the above production method, wherein the seed crystal is sodium acetate trihydrate adsorbed on the surface of the supported crystal. Furthermore, the present invention provides the above-mentioned production method, wherein a solid-liquid separation inhibitor is added to an aqueous sodium acetate solution kept at a melting point or higher.

[0008]

DETAILED DESCRIPTION OF THE INVENTION These inventions will be described in detail below. In the present invention, an aqueous solution of sodium acetate having a concentration of 52 to 60% by weight is maintained at its melting point or higher, and a supported crystal is added to the aqueous solution in an amount equal to or higher than the saturated concentration of the supported crystal, and after filling the container. Solidify by cooling below the melting point in the presence of seed crystals. The heat storage material composition according to the present invention is a heat storage material composition using sodium acetate trihydrate, and the main component acting as the heat storage material is sodium acetate trihydrate. In the present invention, any of sodium acetate trihydrate or anhydrous salt may be used as a raw material, but as an aqueous solution having a concentration of sodium acetate and water converted to sodium acetate anhydrous salt of 52 to 60% by weight. To use.
If it is less than 52% by weight, the heat storage amount becomes too low and 60% by weight
If it exceeds, anhydrous sodium acetate will always be present as an insoluble component, and this amount does not contribute to the heat storage amount, which is not preferable.

In the present invention, the supported crystals are added to the sodium acetate aqueous solution maintained at the melting point or higher. Specific examples of the substance acting as a supported crystal include disodium hydrogen phosphate and sodium chloride. In the present invention,
Since the supported crystals are allowed to exist as crystals during heating and cooling, an amount equal to or higher than the saturated concentration of the supported crystals is added to the aqueous sodium acetate solution. Since the saturation concentration depends on the coexisting ionic species and the liquid temperature, it is difficult to specify the addition ratio in the entire composition, but 0.1 to 10% by weight is preferable, and 0.5 to 5% by weight is more preferable.

In the present invention, supported crystals are added to an aqueous solution of sodium acetate to obtain a mixture, the mixture is charged into a desired container, and then cooled in the presence of seed crystals. If seed crystals are not present, the mixture may not solidify even if cooled to a temperature below the melting point. In the present invention, cooling to a temperature below the melting point is carried out in the presence of seed crystals so as to ensure solidification. When the mixture is solidified by cooling it below its melting point, even if all of the sodium acetate is melted by heating above the melting point again, the supported crystals will have the function of preventing supercooling thereafter. When a mixture of an aqueous solution of sodium acetate and supported crystals is cooled to a temperature lower than the melting point, it will always solidify.
By passing through the solidification process of the sodium acetate aqueous solution once, sodium acetate trihydrate crystals are adsorbed on the surface of the supported crystals, and the adsorbed sodium acetate trihydrate is heated to a temperature higher than the melting point to melt the sodium acetate aqueous solution. Even if it does, it is believed that some of it will remain and will have the effect of preventing supercooling.

Examples of seed crystals used in the present invention include (1) crystals that are crystallized from a part of the mixture after being filled in a container, and (2) separately prepared seed crystals. As a seed crystal used in the present invention, (1) as a method of producing a crystallized crystal after filling from a part of the mixture, (a) taking a long time from the filling into the container to the subsequent sealing, A method of precipitating crystals of sodium acetate trihydrate in (2), and (b) if the mixture has spinnability, at the end of filling into the container, hang down or drop from the outlet of the container containing the mixture. A method of using the thread-like crystals is exemplified. Since all of them crystallize from a part of the mixture, the temperature of the mixture is preferably a little higher than the melting point. The amount of seed crystals is usually about 0.001 to 10% by weight with respect to the total amount of the heat storage material composition, and even an extremely small amount has an effect of preventing supercooling.

The seed crystal used in the present invention (2)
As a separately prepared seed crystal, sodium acetate trihydrate adsorbed on the surface of the supported crystal can be used. As sodium acetate trihydrate adsorbed on the surface of the supported crystal,
It is possible to use sodium acetate trihydrate in which the supported crystals and sodium acetate trihydrate are mixed and ground and adsorbed on the surface of the supported crystals. The mixing ratio of sodium acetate trihydrate and the supported crystals is set in the range of, for example, 1: 9 to 9: 1 by weight, and a mortar,
The sodium acetate trihydrate can be adsorbed on the surface of the supported crystal by mixing and milling using a mixing device which is usually industrially used such as a ball mill and a vibration mill. The addition amount of sodium acetate trihydrate adsorbed on the surface of the supported crystal by the mixing and grinding is effective, and the addition amount is usually 0.002 to 20 with respect to the total amount of the heat storage material composition.
% By weight.

The seed crystal used in the present invention (2)
As a separately prepared seed crystal, after forming a droplet of a mixture of a melt of sodium acetate trihydrate and a supported crystal,
The thing cooled can be mentioned. The supported crystals and seed crystals obtained here are in the form of granules. Sodium acetate 3
The weight ratio of the supported crystals to the molten salt is about 98: 2 to
It is 5:95. The size of the granule is appropriately determined depending on the ease of handling and the diameter of the filling hole in the container, but it is generally about 3 to 15 mm in diameter. The addition amount is 1 to several grains.

In the present invention, the sodium acetate trihydrate or the above granules adsorbed on the surface of the supported crystal by the above mixing / milling may be added to the mixture before it is filled into the container, or after the mixture is filled into the container. There are a method of adding and a method of preliminarily charging in a container.

In the present invention, a solid-liquid separation preventing agent can be added if necessary. When the sodium acetate aqueous solution solidifies, it may separate into trihydrate salt crystals and the remaining aqueous solution, and the solid-liquid separation inhibitor has an effect of preventing such a phenomenon. Examples of the solid-liquid separation preventing agent include polyacrylamide, partially hydrolyzed polyacrylamide, and carboxymethyl cellulose. The preferred addition amount of the solid-liquid separation inhibitor is usually 1 to 10% by weight based on the total amount of the heat storage material composition.

When the solid-liquid separation preventing agent is added, it is preferable that the sodium acetate aqueous solution is kept at a temperature equal to or higher than the melting point, the addition is carried out under stirring, and the stirring is continued until a viscous mixture is formed. The solid-liquid separation preventing agent of the present invention gradually increases in viscosity with continued stirring. Viscosity is about 1P with a rotational viscometer
It is preferable that the viscosity becomes higher with the target of a · s.

[0017]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 47.0 g of an aqueous sodium acetate solution having a concentration of 55.3% by weight was collected in a 100 ml beaker, heated in a water bath at 60 ° C., and 1.4 g of disodium hydrogen phosphate as a supported crystal was added with stirring. After heating for 20 minutes, it was filled in a polyethylene bag. When the filled polyethylene bag was placed vertically and left open for 30 minutes, crystals were deposited on the surface of the liquid, and this was used as a seed crystal. The polyethylene bag was heat-sealed so as not to let air in, then placed in an aluminum laminate bag for sealing, and allowed to stand overnight at room temperature to solidify the whole. A thermocouple was affixed to the surface of the aluminum laminate bag, which was covered with styrofoam having a thickness of 20 mm, and the thermocouple was connected to a multipoint recorder. This is 6
Heat cycle 5 hours at 0 ° C and 2 hours at 20 ° C for 10 hours
Repeated 0 times. 56 ℃ at heating, 54 ℃ at every cooling
It was found that the temperature recording result having a plateau of (part where the temperature change is gradual) was obtained and solidified every time, so that the supercooling prevention was sufficient.

Example 2 Into an agate mortar, 0.21 g of sodium acetate trihydrate and 0.21 g of disodium hydrogen phosphate (anhydrous), which is a supported crystal, were sampled and mixed, and mixed with a pestle and ground to mix. A grind was prepared. A mixture of an aqueous sodium acetate solution and disodium hydrogen phosphate was prepared in the same manner as in Example 1, and then filled in a polyethylene bag. To this, 0.10 g of the above-mentioned mixed / milled product was added, immediately heat-sealed, placed in an aluminum laminate bag for sealing, and allowed to stand overnight at room temperature, whereby the whole was solidified. A thermocouple was attached to this in the same manner as in Example 1, and a heat cycle was applied.
It was the same result as.

Example 3 Into a 50 ml beaker, 30.0 g of an aqueous sodium acetate solution having a concentration of 54% by weight was collected, and heated in a water bath at 60 ° C. as a supported crystal, disodium hydrogen phosphate (anhydrous).
0 g was added and stirred for 30 minutes. As a result of repeating the operation of sucking up the slurry with a dropper while continuing the stirring and dropping the slurry onto the polyethylene film previously laid in the tray several times, 122 droplets were formed. This was placed in a tray at 7 ° C. while being put in a tray, and after 2 hours, it was all solidified into granules. A mixture of an aqueous sodium acetate solution and disodium hydrogen phosphate was prepared in the same manner as in Example 1, and then filled in a polyethylene bag. The above granules (1) were added thereto, immediately heat-sealed, placed in an aluminum laminate bag for sealing, and allowed to stand at room temperature overnight, whereby the whole was solidified. A thermocouple was attached to this and a heat cycle was applied as in Example 1, and the result was the same as in Example 1.

Example 4 47.0 g of an aqueous sodium acetate solution having a concentration of 55.3% by weight was placed in a 100 ml beaker and heated in a water bath at 60 ° C. to give 1.4 g of disodium hydrogen phosphate as a supported crystal.
Was added and heated for 20 minutes, then 1.4 g of partially hydrolyzed polyacrylamide (Sumitomo Chemical Co., Ltd., trade name: Sumifloc FA-30) was added, and stirring was continued for 60 minutes to obtain a viscosity of 3 Pa · s. The solution was made into a thick liquid and then filled in a polyethylene bag. When the filled polyethylene bag was placed vertically and left open for 15 minutes, crystals were deposited on the surface of the liquid, and this was used as a seed crystal. After air was evacuated and heat-sealed, the whole was solidified by placing it in an aluminum laminate bag for sealing and leaving it at room temperature overnight. A thermocouple was attached to this and a heat cycle was applied as in Example 1, and the result was the same as in Example 1.

Example 5 In an agate mortar, 0.21 g of sodium acetate trihydrate and 0.21 g of disodium hydrogen phosphate (anhydrous) as a supported crystal were sampled and mixed, and mixed with a pestle and ground to mix. A grind was prepared. A viscous mixture of an aqueous sodium acetate solution, disodium hydrogen phosphate and partially hydrolyzed polyacrylamide was prepared in the same manner as in Example 4, and then filled in a polyethylene bag. Add the above mixture / milled product 0.1
After 0 g was added, the mixture was immediately heat-sealed, placed in an aluminum laminate bag for sealing, and allowed to stand at room temperature overnight, whereby the whole was solidified. A thermocouple was attached to this and a heat cycle was applied as in Example 1, and the result was the same as in Example 1.

Example 6 A viscous mixture of an aqueous sodium acetate solution, disodium hydrogen phosphate and partially hydrolyzed polyacrylamide was prepared in the same manner as in Example 4, and then filled in a polyethylene bag. To this, one granule prepared in the same manner as in Example 3 was added, immediately heat-sealed, placed in an aluminum laminate bag for sealing, and allowed to stand overnight at room temperature to solidify the whole. A thermocouple was attached to this and a heat cycle was applied as in Example 1, and the result was the same as in Example 1.

Example 7 In Example 3, 1.4 g of carboxymethyl cellulose (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Serogen HE1500F) in place of the partially hydrolyzed polyacrylamide.
A viscous mixture (viscosity 7 Pa · s) was prepared in the same manner as in Example 6 except that was used and then filled in a polyethylene bag. In the same manner as in Example 6, 1 supercooling inhibitor granule was added, immediately heat-sealed, placed in an aluminum laminate bag for sealing, and allowed to stand overnight at room temperature, whereupon the whole solidified. A thermocouple was attached to this and a heat cycle was applied as in Example 1, and the result was the same as in Example 1.

Comparative Example 1 (Example in which seed crystals do not exist) 47.0 g of a 55.3% aqueous solution of sodium acetate was placed in a 100 ml beaker, and 1.4 g of disodium hydrogen phosphate was added while heating in a 65 ° C. water bath. After heating for 20 minutes, it was filled in a polyethylene bag. Immediately after the filling, air was removed and heat-sealed, and then placed in an aluminum laminate bag for sealing, and allowed to stand overnight at room temperature to remain in a liquid state and in a supercooled state.

Comparative Example 2 (Example in which seed crystal does not exist) 47.0 g of a 55.3% aqueous solution of sodium acetate was placed in a 100 ml beaker, and 1.4 g of disodium hydrogen phosphate was added while heating in a 65 ° C. water bath. After heating for 20 minutes, partially hydrolyzed polyacrylamide (Sumitomo Chemical Co., Ltd., trade name: Sumifloc FA-30) 1.4 g
Was added, and stirring was continued for 60 minutes to form a viscous liquid, which was then filled in a polyethylene bag. Immediately after filling, heat sealing was performed to prevent air from entering, sealing was performed by placing it in an aluminum laminate bag, and allowed to stand overnight at room temperature, it was in a liquid state and was in a supercooled state.

[0027]

Industrial Applicability According to the present invention, the latent heat of sodium acetate trihydrate can be utilized to easily produce a heat storage material composition in which supercooling is suppressed, which is industrially useful.

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Claims (7)

[Claims] 1. A sodium acetate aqueous solution having a concentration of 52 to 60% by weight is maintained at a temperature equal to or higher than its melting point, and a supported crystal is added to the aqueous solution in an amount equal to or higher than a saturated concentration of the supported crystal and filled in a container. A method for producing a heat storage material composition, which comprises cooling to a melting point or lower in the presence of seed crystals to solidify. 2. The production method according to claim 1, wherein the supported crystal is disodium hydrogen phosphate or sodium chloride. 3. The production method according to claim 1, wherein the seed crystal is a crystal produced by crystallization of a part of the sodium acetate aqueous solution. 4. The method according to claim 1, wherein the seed crystal is sodium acetate trihydrate adsorbed on the surface of the supported crystal. 5. The sodium acetate trihydrate adsorbed on the surface of the supported crystal is a mixture of the supported crystal and sodium acetate trihydrate.
The production method according to claim 4, wherein the triacetate is sodium acetate trihydrate which is ground and adsorbed on the surface of the supported crystal. 6. The sodium acetate trihydrate adsorbed on the surface of the supported crystal retains the mixture of the supported crystal and the sodium acetate trihydrate melt at the melting point of sodium acetate trihydrate or higher, and the sodium acetate trihydrate is retained on the water repellent material. The production method according to claim 4, which is sodium acetate trihydrate contained in the granules produced by solidifying by cooling after forming droplets on the surface. 7. The method according to any one of claims 1 to 6, wherein a solid-liquid separation inhibitor is added to the sodium acetate aqueous solution maintained at a melting point or higher.