JPH10204423A - Heat storage material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having a melting point of 90 deg.C or lower, not corrosive to metals, not toxic and utilizing the latent heat of fusion by compounding erythritol and sugar alcohol in a specific ratio. SOLUTION: This composition comprises (A) 25 to 55wt.% of erythritol and (B) 45 to 75wt.% of a 5C sugar alcohol, preferably xylitol. It has a melting point preferably in a range from 70 to 90 deg.C, and may contain a paraffin, polyethylene glycol, polyvinyl alcohol or the like, and an additive, e.g., water-insoluble, water-absorptive resin or carboxymethylcellulose.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a heat storage material composition. Specifically, the present invention relates to a heat storage material composition comprising erythritol and a sugar alcohol having 5 carbon atoms and utilizing latent heat of fusion.

[0002]

2. Description of the Related Art A latent heat storage material has a high heat storage density and a constant phase change temperature as compared with a sensible heat storage material, and has been put to practical use taking advantage of the advantage that the heat extraction temperature is stable. . Ice, sodium sulfate decahydrate, calcium chloride hexahydrate, sodium acetate trihydrate and the like are known as latent heat storage materials. However, the phase change temperature of these latent heat storage materials is relatively low, and a high phase change temperature of about 70 to 120 ° C. is desired.
It is unsuitable as a heat storage material for utilizing the waste heat of boilers and automobiles.

The ideal use of the heat storage material composition having a melting point in the range of 70 to 120 ° C. is to use water under normal pressure as a heat medium. For this purpose, the heat storage material needs to have a melting point of 100 ° C. or less. Further, when the heat storage material is a composition that dissolves in water as a heat medium, the heat storage material is used by being filled in a capsule or the like. At this time, since the heat storage material is melted by the heat exchange in the capsule, the melting point of the heat storage material is desirably 90 ° C. or less.

As materials having a melting point in the temperature range of 70 to 90 ° C., inorganic hydrated salts include barium hydroxide octahydrate (melting point 78 ° C., latent heat of fusion 63.8 cal / g), and magnesium nitrate hexahydrate ( Melting point 89 ° C, latent heat of fusion 38.2 cal / g)
And the like. However, magnesium nitrate hexahydrate has a problem of corrosiveness to metals, and barium hydroxide octahydrate has not been put to practical use as a heat storage material in Japan because it is designated as a deleterious substance. Organic materials include paraffin wax and fatty acids, all of which have a heat storage capacity of 3
At present, it is as small as 5.0 to 45.0 cal / ml or less and has not been practically used in terms of cost.

On the other hand, it has been found that some sugar alcohols have a large amount of heat storage, and their use as heat storage materials is being studied. One of them is xylitol (melting point 94-95 ° C; see JP-A-54-65864). Since this is a food, it is safe and there is no problem in using it as a heat storage material, but its melting point is slightly higher at 94 to 95 ° C. Another material is erythritol (melting point 119)
° C; JP-T-63-500946, JP-A-5-32.
No. 963). Since this can also be used as food, there is no problem in safety and the like, but its melting point is as high as 119 ° C. In addition, the 16th Japan Thermophysical Symposium (1995)
In P221), pentaerythritol, pentaglycerin and neopentyl glycol were added to erythritol, so that the phase change temperature of erythritol was 1
Although it is reported that the temperature drops to about 00 ° C., the melting point is still high, and it is difficult to use water at normal pressure as a medium.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat storage material composition having a large amount of heat storage satisfying the following conditions. 1. 1. Melting point is 70 to 90 ° C. 2. No corrosiveness to metal. Non-toxic

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above problems, and as a result, a composition comprising erythritol and a sugar alcohol having 5 carbon atoms in a specific ratio has a melting point of 90 ° C. or lower. And reached the present invention. That is, the gist of the present invention is that erythritol 2
5 to 55% by weight and a C5 sugar alcohol 45 to 75
% By weight of the heat storage material composition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is characterized in that a specific amount of a sugar alcohol having 5 carbon atoms is added to erythritol. The content of a sugar alcohol having 5 carbon atoms is usually 4
It is 5 to 75% by weight, preferably 50 to 70% by weight.
If the content of the sugar alcohol having 5 carbon atoms is less than 45% by weight, the melting points will not be uniform, and two peaks will appear at around 90 ° C and around 110 ° C. If a melting peak exists at around 110 ° C., the heat storage material composition cannot be completely melted using water as a heat medium under normal pressure, and thus cannot sufficiently store heat. On the other hand, if it is more than 75% by weight, the melting point does not become 90 ° C. or lower, and the heat storage becomes insufficient similarly.

In the present invention, the melting point is defined as the peak top temperature when the heat storage material composition is measured with a differential scanning calorimeter (DSC-220C, manufactured by Seiko Instruments Inc.) using a sealed aluminum cell. means. The melting point of 90 ° C. or lower means that there is no peak in a temperature region exceeding 90 ° C. in the analysis by the differential scanning calorimeter. The melting point of the heat storage material composition of the present invention is usually 70 to 90 ° C, preferably 80 to 90 ° C. When the melting point is lower than 70 ° C., it can be used for heating, but for hot water supply use, the melting point is low, so that hot water cannot be obtained. It is not preferable because it cannot be melted and cannot sufficiently store heat. Examples of the sugar alcohol having 5 carbon atoms include xylitol, ribitol, and arabitol, and these may be used alone or in combination of two or more. Preferably, xylitol or ribitol, more preferably xylitol is used.

[0010] The heat storage material composition of the present invention exhibits a so-called supercooling phenomenon in which it is heated to a temperature above its melting point, melted, and then does not crystallize even when cooled to below the melting point. At this time, if a supercooling inhibitor is not added to the heat storage material composition of the present invention, a metastable state is maintained up to around 0 ° C., and when heat is required, the heat storage material composition is subjected to impact, vibration, stirring, ultrasonic waves. Crystallization can be arbitrarily performed by providing crystallization promoting means such as irradiation. Conversely, the heat storage material composition of the present invention may contain an inorganic salt such as calcium carbonate, calcium phosphate, calcium sulfate, calcium pyrophosphate, aluminum phosphate, silver phosphate, silver sulfate, silver chloride or silver iodide, calcium stearate, and stearic acid. By adding a supercooling inhibitor such as an organic salt of a long-chain fatty acid such as magnesium, barium stearate or calcium palmitate, the melted heat storage material composition can be crystallized near the melting point.

The heat storage material composition of the present invention may be used in combination with a known heat storage material such as paraffin, polyethylene glycol, polyvinyl alcohol, polyethylene, or crosslinked polyethylene, if necessary. In addition, water-insoluble water-absorbing resins, thickeners such as carboxymethylcellulose, sodium alginate, potassium alginate, and finely divided silica; antioxidants such as phenols, amines, and hydroxyamines; chromates, polyphosphates, and nitrous acid An additive such as a metal corrosion inhibitor such as sodium may be contained. The method for preparing the heat storage material composition of the present invention is not particularly limited,
Erythritol, a polyhydric alcohol, an additive and a known heat storage material may be mixed and dispersed uniformly if necessary. In order to disperse the erythritol and the polyhydric alcohol more uniformly, a method of heating the erythritol and the polyhydric alcohol to the melting point or higher and stirring and mixing them may be mentioned.

Examples of the method of using the heat storage material composition of the present invention include a capsule type in which the heat storage container is filled with the heat storage material composition and a microcapsule type in which a heat storage container is not required. The capsule type is obtained by injecting the heat storage material composition into a heat storage container such as a capsule and sealing the heat storage container. The material of the capsule may be any material that does not deform or melt in the operating temperature range, and examples thereof include metals such as stainless steel and aluminum, glass, and engineering plastics such as polycarbonate. The shape of the capsule is not particularly limited, and examples thereof include a sphere, a plate, a pipe, a constricted cylinder, a twin sphere, and a corrugated plate, and are appropriately selected depending on the application. The microcapsule type is a product in which fine heat storage material particles or their aggregates are covered with a coating such as a resin that does not melt and deteriorate in the operating temperature range.
There is an advantage that heat transfer efficiency is high.

In the heat storage system, a heat medium flows around the capsules and the microcapsules, and the metal and resin constituting the capsules and the microcapsules serve as a heat exchanger to store and radiate heat. As a use of the heat storage material composition of the present invention, for the purpose of hot water supply, a heat storage type electric water heater using midnight power can be considered. This can be shared with a 24-hour bath if the system is combined. Further, there is a problem that the activity of the catalyst does not increase and harmful gas is emitted until the catalyst temperature rises in a cold region such as Northern Europe when the engine of the vehicle is started. In order to solve this problem, it is conceivable to store the heat of the radiator during traveling and use it at the time of starting to accelerate the temperature rise. The heat medium in the radiator is an antifreeze (ethylene glycol aqueous solution), but the liquid temperature during running is around 100 ° C.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention. Examples 1 to 3 and Comparative Examples 1 to 8 Erythritol was manufactured by Mitsubishi Chemical Foods Co., Ltd., and xylitol was manufactured by Tokyo Chemical Industry Co., Ltd. Table-Erythritol and xylitol so that total amount is 1g
The components were blended in the weight ratio shown in FIG. 1 and mixed in a mortar at room temperature until homogeneous. The melting temperature and latent heat of fusion of the obtained heat storage material composition were measured with a differential scanning calorimeter (DSC-220C, manufactured by Seiko Instruments Inc.) using an aluminum sealed cell. The results are shown in Table 1. In addition, the melting point measured the peak top temperature. Comparative Examples 9 and 10 In Example 1, xylitol was replaced by pentaerythritol (Comparative Example 9) and pentaglycerin (Comparative Example 10).
The procedure was performed in the same manner as in Example 1 except for changing to. Table-Results
It is shown in FIG.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

According to the present invention, it has a sufficient heat storage amount,
A heat storage material composition that is safe for the human body and can use water at normal pressure as a heat medium is obtained.

Claims (3)

[Claims] 1. A heat storage material composition comprising 25 to 55% by weight of erythritol and 45 to 75% by weight of a sugar alcohol having 5 carbon atoms. 2. The heat storage material composition according to claim 1, wherein the sugar alcohol having 5 carbon atoms is xylitol. 3. The heat storage material composition according to claim 1, wherein the melting point is 70 to 90 ° C.