JP6045944B2 - Heat storage material - Google Patents

Description

  The present invention relates to a heat storage material used when a substance is cooled or warmed.

  A heat storage material such as a cold insulation material used to maintain a cold temperature and a heat storage material such as a heat insulation material used to maintain a warm temperature is enclosed in a container, a bag, or the like, and is used in a heat storage container (a heat storage container for cold insulation, a heat insulation material). The heat storage container) is housed in a housing container, a housing box or the like together with a processed material such as food and used as a temperature adjusting material for the processed material.

  There is a material using latent heat as such a heat storage material, and a material using an inorganic compound such as acetate, sulfate or nitrate is known as a material using latent heat. In addition, in order to increase the heat exchange rate of these inorganic compound heat storage materials, a method of encapsulating the heat storage material in a microcapsule to increase the surface area per unit volume has also been proposed (for example, Patent Documents 1 and 2). reference).

  When the heat storage material is enclosed in the microcapsules in this way, not only the heat exchange rate is improved, but even if the heat storage material becomes liquid in the heat storage state, it is in the state of the microcapsule and is in appearance. Remains a solid as a microcapsule and is therefore very convenient in the use of heat storage materials.

Japanese Unexamined Patent Publication No. 55-40524 JP-A-5-163486

  However, when a capsule that contains an inorganic compound that accompanies a phase change in heat storage is prepared and a heat storage operation is attempted using this capsule, the following problems arise. That is, capsules encapsulating an inorganic compound with a phase change are used for various purposes by repeating heat absorption / dissipation by heating / cooling. At this time, the phase change encapsulated in the capsule is changed. A phenomenon in which the temperature of the melting point and the freezing point of the inorganic compound is different, that is, a remarkable supercooling phenomenon (a phenomenon in which the freezing point is lowered) occurs. When such a supercooling phenomenon occurs in the heat storage operation, solidification does not occur completely in a predetermined temperature range, and the following problem occurs, for example.

  For example, when a heat storage material is used as a heat insulating material, heat is stored at the melting point of the heat storage material, and the heat stored at the freezing point is released, but when this supercooling phenomenon occurs, the freezing point exceeds the melting point. The stored heat is released at a temperature lower than the desired temperature. For example, the workpiece cannot be maintained at the desired temperature. Also, for example, when using a heat storage material as a cold insulation material, cold heat is stored at the freezing point of the heat storage material, and the heat of the cold stored at the melting point is radiated, but when this supercooling phenomenon occurs, the freezing point is Since the temperature greatly decreases, the temperature for storing the cold energy decreases, and a large amount of energy is consumed to store the cold energy in the heat storage material.

  An object of the present invention is to provide a heat storage material that can suppress a supercooling phenomenon and reduce a difference between a melting point and a freezing point when heating and cooling in a heat storage material made of an inorganic compound accompanied by a phase change. is there.

  As a result of studying to achieve the above-described problems, the present inventor has found that the supercooling phenomenon can be suppressed by including an anionic surfactant in a heat storage material containing an inorganic compound accompanied by a phase change.

  The heat storage material according to claim 1 of the present invention is a heat storage material containing an inorganic compound accompanied by a phase change, and includes an anionic surfactant together with the inorganic compound.

  In the heat storage material according to claim 2 of the present invention, the anionic surfactant is one of sodium alkyl sulfate, sodium alkyl phosphate, potassium alkyl sulfate and potassium alkyl phosphate, or any two or more of these. It is characterized by being a mixture of

  In the heat storage material according to claim 3 of the present invention, the content ratio of the anionic surfactant with respect to the inorganic compound is 0.0005 to 5% by weight.

  Furthermore, in the heat storage material according to claim 4 of the present invention, the content ratio of the anionic surfactant to the inorganic compound is 0.001 to 1% by weight.

  According to the heat storage material according to claim 1 of the present invention, since the anionic surfactant is included in the heat storage material containing the inorganic compound accompanied by the phase change, the anionic surfactant becomes a nucleating agent (when solidifying. It can function as a core), thereby suppressing the occurrence of the supercooling phenomenon of the heat storage material.

  Generally, in order to prevent the supercooling phenomenon of the phase change material, a nucleating agent is added to the phase change material. The most effective nucleating agent is the crystal of the phase change material itself, but the supercooling phenomenon cannot be prevented unless a part of the phase change material is kept in the crystal at any temperature state. Is not a realistic solution and is considered impossible.

  For this reason, an anionic surfactant is added as a nucleating agent. In this heat storage material, the inorganic compound becomes a substance accompanied by a phase change material that stores heat, and the anionic surfactant becomes a nucleating agent. That is, when the phase change material (inorganic compound) cools and solidifies, the anionic surfactant acts as a nucleating agent, and the crystallization reaction of the phase change material is promoted using this as a nucleus, resulting in the phase change. The solidification of the substance proceeds very smoothly and the occurrence of the supercooling phenomenon can be effectively suppressed.

  Moreover, according to the heat storage material according to claim 2 of the present invention, the anionic surfactant is any one of sodium alkyl sulfate, sodium alkyl phosphate, potassium alkyl sulfate and potassium alkyl phosphate, or any two of them. Since it is a mixture as described above, it effectively functions as a nucleating agent for the phase change material (inorganic compound), and the occurrence of the supercooling phenomenon of the heat storage material (inorganic compound) can be effectively suppressed.

  Moreover, according to the heat storage material according to claim 3 of the present invention, since the content ratio of the anionic surfactant to the inorganic compound is 0.0005 to 5% by weight, the anionic surfactant is effective as a nucleating agent. It can function to suppress the occurrence of the supercooling phenomenon. If the added amount of the anionic surfactant is more than 5% by weight, the crystallization of the inorganic compound is hindered to solidify, so that it does not function as a heat storage material, and the added amount of the anionic surfactant is more than 0.0005% by weight. When the amount is too small, the effect of preventing the overcooling by the anionic surfactant is lowered. For this reason, it is not preferable to deviate from the range of 0.0005 to 5% by weight.

  Moreover, according to the heat storage material according to claim 4 of the present invention, since the content ratio of the anionic surfactant to the inorganic compound is 0.001 to 1% by weight, the anionic surfactant is very useful as a nucleating agent. The temperature between the melting point and the freezing point is almost eliminated, and the occurrence of a supercooling phenomenon can be prevented.

Sectional drawing which shows the usage example of the thermal storage material according to this invention simply. The figure which shows the relationship between the addition amount of an anionic surfactant, and the generation | occurrence | production degree of a supercooling phenomenon.

  Embodiments of a heat storage material according to the present invention will be described below with reference to the accompanying drawings. In FIG. 1, this heat storage material 2 contains an inorganic compound 4 as a phase change substance that causes a phase change and an anionic surfactant 6 as a nucleating agent. The heat storage material 2 is, for example, a synthetic resin bag. 8 and so on. For example, when using it as a heat insulating material for heat-retaining processed products such as food, the heat storage material 2 stores the heat, and the heat of solidification when solidified is used for heat retention. Moreover, when using as a cold insulating material for cold-working a processed material etc., cold heat is stored in this heat storage material 2, and the heat of fusion at the time of melting is utilized for cold storage.

  In this heat storage material 2, in order to store heat, an inorganic compound 4 as a phase change material is used, and any inorganic compound having a melting point or a freezing point can be used. The inorganic compound 4 has a large heat storage amount per unit weight and is suitable as a heat storage material. As the inorganic compound 4, acetate, sulfate, nitrate, hydrochloride, phosphate, sulfite, nitrite, pyrophosphate Salts, salicylates and the like can be conveniently used, and among these inorganic compounds, sulfates, acetates and pyrophosphates are more preferable. Since the aliphatic hydrocarbons of these inorganic compounds increase in melting point with an increase in the number of carbons, compounds having a melting point according to the purpose can be selected, or two or more types can be used in combination.

  As the acetate, for example, sodium acetate, potassium acetate, barium acetate, sodium acetate hydrate, potassium acetate hydrate, barium acetate hydrate and the like can be used, and as the sulfate, for example, sodium sulfate, potassium sulfate , Barium sulfate, sodium sulfate hydrate, potassium sulfate hydrate, barium sulfate hydrate, etc. can be used. Examples of nitrates include sodium nitrate, potassium nitrate, barium nitrate, sodium nitrate hydrate, potassium nitrate hydrate. , Barium nitrate hydrate, etc. can be used, and as the hydrochloride, for example, sodium hydrochloride, potassium hydrochloride, barium hydrochloride, sodium hydrochloride hydrate, potassium hydrochloride hydrate, barium hydrochloride hydrate, etc. As phosphate, sodium phosphate, potassium phosphate, barium phosphate Sodium phosphate hydrate, potassium phosphate hydrate, barium phosphate hydrate, etc. can be used. Examples of sulfites include sodium sulfite, potassium sulfite, barium sulfite, sodium sulfite hydrate, potassium sulfite Hydrate, barium sulfite hydrate, etc. can be used. Examples of nitrites include sodium nitrite, potassium nitrite, barium nitrite, sodium nitrite hydrate, potassium nitrite hydrate, barium nitrite water As pyrophosphates, for example, sodium pyrophosphate, potassium pyrophosphate, barium pyrophosphate, sodium pyrophosphate hydrate, potassium pyrophosphate hydrate, barium pyrophosphate hydrate, etc. Examples of salicylates include sodium salicylate, Potassium salicylic acid, salicylic acid barium, sodium salicylate hydrate, potassium salicylate hydrate, and the like can be used salicylic barium hydrate.

  Examples of the anionic surfactant 6 added to the inorganic compound 4 as described above include sodium alkyl sulfate, sodium alkyl phosphate, potassium alkyl sulfate, potassium alkyl phosphate, or any mixture of two or more thereof. Such an anionic surfactant 6 effectively functions as a nucleating agent with respect to the inorganic compound 4 described above, and suppresses the occurrence of a supercooling phenomenon when used as the heat storage material 2. Or it can be made to hardly occur.

  The addition amount of the anionic surfactant 6 is preferably 0.0005 to 5% by weight in terms of the content of the anionic surfactant with respect to the inorganic compound. If the amount added is less than 0.0005% by weight, the effect of preventing overcooling by the anionic surfactant 6 is reduced. This addition amount is more preferably 0.001 to 1% by weight. In this range, the supercooling phenomenon of the heat storage material 2 hardly occurs, and an excellent heat storage material 2 can be provided.

  As mentioned above, although the Example of the thermal storage material according to this invention was described, this invention is not limited to this Example, A various deformation | transformation thru | or correction | amendment are possible without deviating from the scope of the present invention.

  In order to confirm the effect of the heat storage material according to the present invention, the degree of occurrence of the supercooling phenomenon is investigated by adjusting the heat storage material as follows, and the degree of occurrence of this supercooling phenomenon is measured by measuring the temperature difference between the melting point and the freezing point. I went there.

  In Example 1, sodium dodecyl sulfate (reagent manufactured by Aldrich Co., Ltd.) as an anionic surfactant was added in a predetermined amount (relative to the inorganic compound) to 5 g of sodium acetate trihydrate (melting point: 40 ° C.) as an inorganic compound of a phase change substance. Content ratio of anionic surfactant (% by weight): 0.0001% by weight, 0.0005% by weight, 0.001% by weight, 0.01% by weight, 0.05% by weight, 0.1% by weight, 0.8% by weight. 3 wt%, 0.5% wt%, 1.0 wt%, 5 wt%, 10 wt%) were added to adjust the heat storage material.

  As Example 2, a predetermined amount of sodium dodecyl sulfate (reagent manufactured by Aldrich Co., Ltd.) as an anionic surfactant was added to 5 g (melting point: 30 ° C.) of sodium sulfate decahydrate as an inorganic compound of a phase change substance (0. 0001%, 0.0005%, 0.001%, 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 1.0% (Weight%, 5 weight%, 10 weight%) was added to adjust the heat storage material.

  As Example 3, a predetermined amount of sodium dodecyl phosphate (reagent manufactured by Aldrich Co., Ltd.) as an anionic surfactant was added to 5 g (melting point: 40 ° C.) of sodium acetate trihydrate as an inorganic compound of a phase change substance (0. 0001%, 0.0005%, 0.001%, 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 1.0% (Weight%, 5 weight%, 10 weight%) was added to adjust the heat storage material.

  Further, as Example 4, a predetermined amount of sodium dodecyl phosphate (reagent manufactured by Aldrich Co., Ltd.) as an anionic surfactant was added to 5 g (melting point: 30 ° C.) of sodium sulfate decahydrate as an inorganic compound of a phase change substance ( 0.0001%, 0.0005%, 0.001%, 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 1% 0.0 wt%, 5 wt%, 10 wt%) was added to prepare the heat storage material.

  For comparison, as Comparative Example 1, sodium acetate trihydrate itself used as an inorganic compound in Example 1 was used as a heat storage material. Further, as Comparative Example 2, sodium sulfate decahydrate itself used as an inorganic compound in Example 2 was used as a heat storage material.

[Measurement of degree of supercooling]
About the thermal storage material of Examples 1-4 and Comparative Examples 1-2, temperature difference ((DELTA) T = T1-T2) of melting | fusing point (T1) and freezing point (T2) using a differential scanning calorimeter (made by Shimadzu Corporation) Was measured. As this temperature difference (ΔT) is smaller, the freezing point (T2) is less decreased with respect to the melting point (T1), and the degree of supercooling can be reduced.

  The measurement result of the degree of supercooling was as shown in FIG. FIG. 2 shows the relationship between the addition ratio (% by weight) of the anionic surfactant and the temperature difference (ΔT = T1−T2). As is clear from FIG. By adding the activator, it is possible to suppress the occurrence of the supercooling phenomenon of the heat storage material, and this temperature difference (ΔT) is small especially in the range of 0.001 to 1% by weight of the anionic surfactant content. It was found that the supercooling phenomenon hardly occurred.

2 Thermal Storage Material 4 Inorganic Compound 6 Anionic Surfactant 8 Synthetic Resin Bag

Claims (3)

A heat storage material comprising an inorganic compound with a phase change, wherein the inorganic compound with viewing containing an anionic surfactant, the anionic surfactant is sodium alkyl sulfate, sodium alkyl phosphate, potassium alkyl sulfate and alkyl phosphate A heat storage material characterized by being any one of potassium acid or a mixture of any two or more thereof . The heat storage material according to claim 1 , wherein a content ratio of the anionic surfactant with respect to the inorganic compound is 0.0005 to 5% by weight. The heat storage material according to claim 1 , wherein a content ratio of the anionic surfactant with respect to the inorganic compound is 0.001 to 1% by weight.

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