JP7121673B2 - Latent heat storage material composition - Google Patents

Description

The present disclosure relates to a latent heat storage material composition in which an additive for suppressing the supercooling phenomenon of the latent heat storage material is added to a latent heat storage material that stores heat or releases heat by utilizing the input and output of latent heat accompanying a phase change.

A latent heat storage material (PCM: Phase Change Material) has the physical property of storing or releasing heat by utilizing the input and output of latent heat accompanying a phase change. Energy can be effectively used without waste by extracting it according to the situation. There are many substances that can be used as latent heat storage materials, but among them, alum-based latent heat storage materials are expected to be applied in a wide range of fields because of their excellent heat storage performance.

On the other hand, the latent heat storage material sometimes undergoes a supercooling phenomenon in which it does not crystallize even when it is cooled from a molten state to a temperature below the freezing point. When the supercooling phenomenon occurs, the latent heat storage material that has once melted does not solidify in the molten state, and the latent heat cannot be dissipated. It becomes impossible to use the latent heat stored in the time lag. In order to prevent such a supercooling phenomenon, a supercooling prevention agent is generally blended together with the latent heat storage material, as exemplified in Patent Document 1. The supercooling inhibitor is an additive that promotes the induction of crystallization of the latent heat storage material in the molten state.

Patent Document 1 discloses that calcium fluoride (CaF ₂ ) crystals and sulfur (S) crystals are added to ammonium alum (melting point 94 to 95° C.), which is an alum-based latent heat storage material as a main component, as supercooling inhibitors. It is a heat storage material with a mixture of Patent Literature 1 discloses a method of placing a mixture of calcium fluoride crystals and sulfur crystals in a cage and suspending it in an ammonium alum solution, or by directly adding calcium fluoride crystals and sulfur crystals to ammonium alum. It adopts a means to put it into the solution of In Patent Document 1, in canceling the supercooling phenomenon of the ammonium alum solution by any means, keeping calcium fluoride crystals and sulfur crystals in contact with each other or close to each other in the ammonium alum solution: It is necessary for nucleation.

Japanese Patent Publication No. 57-349

However, in Patent Document 1, the anti-supercooling agent is a mixture of calcium fluoride crystals and sulfur crystals. There is a risk that the nuclei necessary for the formation of the nuclei will be difficult to form in the ammonium alum melt. In addition, the supercooling inhibitor is a mixture of calcium fluoride crystals and sulfur crystals, and it is necessary to keep them in contact or close to each other for nucleation, so the heat storage of Patent Document 1 For example, when the material is used for applications such as in-vehicle installation in automobiles and heat-retaining transportation such as lunches and lunches, the calcium fluoride crystals and sulfur crystals are greatly separated from each other during transportation, and it is used as a supercooling prevention agent. There is also a risk that it will stop working. Therefore, the heat storage material of Patent Document 1, which uses a mixture of calcium fluoride crystals and sulfur crystals as an anti-supercooling agent, is a technology that is not convenient to use.

The present disclosure has been made to solve the above problems, and the latent heat storage material mainly composed of alum suppresses the supercooling phenomenon more reliably and dissipates the stored latent heat. An object of the present invention is to provide a latent heat storage material composition capable of

One aspect of the present disclosure, which has been made to solve the above problems, is based on a latent heat storage material that stores heat or releases heat by utilizing the input and output of latent heat accompanying a phase change, and adjusts the physical properties of the latent heat storage material. wherein the latent heat storage material is a first alum, and the additive induces crystallization of the first alum in a molten state. and the anti-supercooling agent is a second alum having a higher melting point than the first alum.

According to this aspect, crystal nuclei of alum (latent heat storage material) are generated as nuclei necessary for suppressing supercooling of alum. Therefore, the crystallization of the latent heat storage material is induced by the formation of alum crystal nuclei based on the supercooling inhibitor, and the latent heat storage material composition has a melting point and a freezing point of the latent heat storage material during the cooling process from the melt state. It is possible to dissipate the stored latent heat while suppressing the deviation of .

In particular, the first alum used as a latent heat storage material and the second alum used as a supercooling inhibitor are both alums. Therefore, the supercooling prevention agent composed of the second alum has the same lattice constant and bonding property as the latent heat storage material composed of the first alum, so the latent heat storage material composed of the first alum Satisfies the requirements for supercooling prevention agents for materials.

Therefore, it is possible to more reliably suppress the occurrence of supercooling in the latent heat storage material containing alum as a main component, and to dissipate the stored latent heat.

In the above aspect, the blending ratio of the second alum to the weight of the entire latent heat storage material composition is preferably 10 wt % or less.

According to this aspect, the blending ratio of the second alum to the weight of the entire latent heat storage material composition is 10 wt % or less so as not to impair the high heat storage capacity of the first alum. As a result, in the process of cooling the latent heat storage material composition from the melt state more reliably, the difference between the melting point and the freezing point of the latent heat storage material is suppressed. expression can be suppressed.

In the above aspect, each of the first alum and the second alum is an inorganic salt crystal composed of a double salt of a monovalent cation sulfate and a trivalent metal ion sulfate, and The monovalent cation is any one of ammonium ion, potassium ion, sodium ion, and rubidium ion, and the trivalent metal ion is iron ion (III), aluminum ion, and chromium ion (III). is preferably either

According to this aspect, the cost is reduced because alum, which is widely distributed in the market, is easily available, and is inexpensive, is used.

In the above embodiment, the first alum is iron alum dodecahydrate ( _FeNH4 ( _SO4 ) _2.12H2O ) and the _second alum is ammonium alum dodecahydrate. ( _AlNH4 ( _SO4 ) _2.12H2O ), potassium alum dodecahydrate ( _AlK ( _SO4 ) _2.12H2O ), sodium alum dodecahydrate ( _AlNa ( _SO4 ) _{2.12H 2} O).

According to this aspect, it is possible to more reliably suppress the supercooling phenomenon in the latent heat storage material containing alum as a main component while reducing the cost.

According to the latent heat storage material composition of the present disclosure, it is possible to more reliably suppress the occurrence of supercooling in the latent heat storage material containing alum as a main component, and to dissipate the stored latent heat.

It is a figure which shows typically the structural component of the latent heat storage material composition of this embodiment. Sample no. 1 is a graph showing the results of a heat radiation test of the latent heat storage material No. 1. FIG. Sample no. 2 is a graph showing the heat radiation test results of latent heat storage material compositions Nos. 2 to 4. FIG. Sample no. 1 latent heat storage material and sample No. 2 is a table showing a list of heat radiation start temperatures of latent heat storage material compositions 2 to 4. FIG.

(embodiment)
The latent heat storage material composition of this embodiment will be described in detail below. The purpose of the latent heat storage material composition is to temporarily store heat provided from a heat supply source in the latent heat storage material, and then utilize the thermal energy of the latent heat stored in the latent heat storage material at the heat demand destination with a time lag. used in Such a latent heat storage material composition is liquid-tightly and air-tightly filled in a filled container (not shown) housed in a space of a predetermined housing means in a leak-free manner. By utilizing the input and output of latent heat, the stored heat can be extracted as needed, and the cycle of heat storage and heat release is repeated multiple times.

The latent heat storage material composition is composed mainly of a latent heat storage material that stores or dissipates heat by utilizing the input and output of latent heat associated with a phase change, and is blended with an additive that adjusts the physical properties of the latent heat storage material. ing. In this embodiment, the latent heat storage material is the first alum. The additive is an anti-supercooling agent that promotes the induction of crystallization of the first alum in the molten state. Moreover, in this embodiment, the supercooling prevention agent is the second alum having a higher melting point than the first alum used as the latent heat storage material. The blending ratio of the second alum to the total weight of the latent heat storage material composition is 10 wt % or less.

Alum is a general term for a double salt of a monovalent cation sulfate (M ^I ₂ (SO ₄ )) and a trivalent metal ion sulfate (M ^III ₂ (SO ₄ ) ₃ ). , M ^I M ^III (SO ₄ ) ₂ ·nH ₂ O (n is 0 or more).

Next, the configuration of the latent heat storage material composition will be specifically described with reference to examples.

(Example)
As shown in FIG. 1, the latent heat storage material composition 1 according to this example is a heat storage material in which a latent heat storage material 10 and an additive 20 are blended.

In the present embodiment, the latent heat storage material 10 is composed of iron alum dodecahydrate (ammonium iron (III) sulfate.12-hydrate, FeNH ₄ (SO ₄ ) 2.12H ₂ O) as the _first alum. Seeds. The melting point of this iron alum dodecahydrate is 40°C. In the following description, iron alum dodecahydrate may be simply referred to as "iron alum".

The additive 20 is an anti-supercooling agent 21, which in this embodiment is a second alum having a higher melting point than the first alum. Examples of the second alum include ammonium alum dodecahydrate (ammonium aluminum sulfate.12 _- hydrate, AlNH4( _SO4 ) _2.12H2O ) and potassium alum dodecahydrate (potassium aluminum sulfate.12H2O). hydrate, _AlK ( _SO4 ) _2.12H2O ), sodium alum dodecahydrate (sodium aluminum sulfate.12hydrate, AlNa _{( SO4} ) _2.12H2O ) .

In the following description, ammonium alum dodecahydrate may be simply referred to as "ammonium alum", potassium alum dodecahydrate may be simply referred to as "potassium alum", and sodium alum dodecahydrate may be referred to simply as "potassium alum". Wako is sometimes simply referred to as "sodium alum".

The melting point of ammonium alum dodecahydrate is 93.5°C, the melting point of potassium alum dodecahydrate is 92.5°C, and the melting point of sodium alum dodecahydrate is 60°C. .

<Implementation of verification experiment>
Next, an experiment was conducted for the purpose of verifying the effect of the supercooling prevention agent 21 in suppressing the supercooling phenomenon in the latent heat storage material 10 . The experiment was conducted using a sample in which 50 g of the latent heat storage material composition 1 according to the above-described example was sealed in an aluminum laminate bag in a vacuum state.

<Experimental method>
In the experiment, the latent heat storage material composition 1 or the latent heat storage material 10 (hereinafter referred to as “latent heat storage material composition 1 or the like”) in the sample was first heated to 60° C. by the heater in the constant temperature bath. heat up. Then, after confirming in advance that the latent heat storage material composition 1 and the like were in a melt state in which they were completely melted, the operation of the heater was turned off. Next, while the temperature of the latent heat storage material composition 1 and the like is being measured with the door of the constant temperature bath closed, the temperature inside the constant temperature bath is lowered from 60°C to 0°C at a rate of 10°C/h. The latent heat storage material composition 1 and the like in the molten state were cooled until they were in a completely solid state. In all the experiments, at the same time that the operation of the heater was switched off, measurement of the state temperature of the latent heat storage material composition 1, etc. was started, and the temperature was continuously maintained until the temperature of the latent heat storage material composition 1, etc. almost disappeared. I made a measurement. At the same time, the atmospheric temperature in the constant temperature bath was also measured.

The conditions for each experiment are as follows.
<Conditions of Experiment 1>
・Sample 1; latent heat storage material 10
・Latent heat storage material 10: iron alum dodecahydrate ・Additive 20: not blended

<Conditions of Experiment 2>
・Sample 2: latent heat storage material composition 1
・Latent heat storage material 10; iron alum dodecahydrate ・Additive 20; antisupercooling agent 21
Supercooling prevention agent 21: ammonium alum dodecahydrate Mixing ratio (wt%) of latent heat storage material 10 and supercooling prevention agent 21; 95:5

<Conditions of Experiment 3>
・Sample 3: latent heat storage material composition 1
・Latent heat storage material 10; iron alum dodecahydrate ・Additive 20; antisupercooling agent 21
・Supercooling prevention agent 21: potassium alum dodecahydrate ・Ratio (wt%) of latent heat storage material 10 and supercooling prevention agent 21; 95:5

<Conditions of Experiment 4>
・Sample 4: latent heat storage material composition 1
・Latent heat storage material 10; iron alum dodecahydrate ・Additive 20; antisupercooling agent 21
Supercooling prevention agent 21; sodium alum dodecahydrate Mixing ratio (wt%) of latent heat storage material 10 and supercooling prevention agent 21; 95:5

<Experimental results>
According to the results of Experiment 1, as shown in FIG. 2, after the start of temperature measurement, the ambient temperature in the constant temperature bath continued to drop over time. On the other hand, the temperature of the latent heat storage material 10 (iron alum) of the sample 1 according to the example increases with the passage of time until time t0a when the ambient temperature in the constant temperature bath reaches around 11° C. (=temperature T0a). kept going down. Then, after the time t0a, the temperature of the latent heat storage material 10 of the sample 1 gradually changed and began to drop at a slow temperature drop rate. When time t0b is reached, the temperature of the latent heat storage material 10 of sample 1 becomes almost the same when the ambient temperature in the constant temperature bath is around 0° C. (=temperature T0b). In this manner, the behavior of the latent heat radiation stored in the latent heat storage material 10 was confirmed in the latent heat storage material 10 of the sample 1 from the time t0a to the time t0b.

Thus, the heat radiation start temperature of the latent heat storage material 10 (iron alum) of Sample 1 was 11° C., as shown in FIG.

On the other hand, in the results of Experiments 2 to 4, as shown in FIG. 3, the ambient temperature in the constant temperature bath continued to decrease with the lapse of time after the start of temperature measurement. On the other hand, the temperature of the latent heat storage material composition 1 of samples 2 to 4 according to the example was changed until time t1a when the ambient temperature in the constant temperature bath reached around 22 to 24° C. (=T1a). continued to fall with Then, after time t1a, the temperature of the latent heat storage material composition 1 of samples 2 to 4 gradually changed and began to drop at a slow rate of temperature drop. When time t1b was reached, the temperatures of the latent heat storage material compositions 1 of samples 2 to 4 became substantially the same when the ambient temperature in the constant temperature bath was around 0° C. (=T1b). Thus, the behavior of the latent heat release stored in the latent heat storage material composition 1 of samples 2 to 4 was confirmed from time t1a to time t1b.

In this manner, the heat release starting temperature of the latent heat storage material composition 1 of samples 2 to 4 was 22 to 24° C., as shown in FIG. Specifically, the heat radiation start temperature of the latent heat storage material composition 1 (iron alum + ammonium alum) of sample 2 was 22.1°C. Further, the heat radiation start temperature of the latent heat storage material composition 1 (iron alum + potassium alum) of sample 3 was 24°C. The heat radiation start temperature of the latent heat storage material composition 1 (iron alum + sodium alum) of sample 4 was 22.5°C.

<Discussion>
The latent heat storage material accumulates latent heat during the phase change from the solid state to the melt state by heating above its melting point and stores heat. At the time of phase change, the stored latent heat is radiated to the outside. In Experiment 1, the latent heat storage material 10 of Sample 1 contained only a single type of iron alum. Therefore, in sample 1, when the temperature of the melt of the latent heat storage material 10 is cooled to a temperature lower than the melting point of 40°C, the iron alum, which was originally in a melted state of 40°C or higher, is theoretically solid. Due to the phase change to the state, the stored latent heat is radiated to the outside, and the state temperature of the latent heat storage material 10 should rise temporarily along with this heat radiation.

However, according to experimental results, the behavior of latent heat radiation from the latent heat storage material 10 does not exist until the temperature reaches 11°C. It was found that a supercooling phenomenon that does not cause a phase change occurs. From this, in sample 1 of experiment 1, the nucleus necessary to suppress such a supercooling phenomenon does not exist in the melt of iron alum (latent heat storage material 10), and the supercooling prevention agent is also added. It is considered that the supercooling phenomenon occurred in the latent heat storage material 10 because it did not cool down.

On the other hand, in samples 2 to 4 according to Examples 2 to 4, while the latent heat storage material composition 1 was continuously cooled, the state temperature of the latent heat storage material composition 1 was lower than the melting point, but When the temperature reached 22° C. to 24° C., the temperature gradually changed and began to drop at a slow rate. Then, it was found that the state temperature of the latent heat storage material composition 1 now has a temperature difference with respect to the ambient temperature, which had almost the same temperature trend until then, and the supercooling phenomenon is suppressed. From this, in samples 2 to 4 according to Examples 2 to 4, in the latent heat storage material composition 1, the supercooling phenomenon is suppressed, and the latent heat release accompanying the phase change from the melt state to the solid state It is considered that the latent heat storage material composition 1 itself was heated by the above.

In other words, in the latent heat storage material composition 1, in addition to the latent heat storage material 10, the supercooling prevention agent 21 made of the second alum is commonly blended. The nucleus necessary to suppress the supercooling phenomenon exists in the melt of the iron alum latent heat storage material 10 . Therefore, it is considered that the latent heat storage material 10 made of iron alum suppresses the supercooling phenomenon.

More specifically, in the process of solidifying the melted alum, alum crystal nuclei are first formed in the melt. Subsequently, alum crystals grow starting from the crystal nuclei. Finally, crystal growth spreads over the entire melt and solidification is completed. On the other hand, the supercooling phenomenon occurs because crystal nuclei are not formed even when the melt is cooled.

Here, the supercooling inhibitor serves as a substitute for crystal nuclei and serves as a starting point for crystal growth. It is generally said that the condition for the supercooling inhibitor is that the lattice constant and bondability with the base material are the same. Alum (alum crystal hydrate) has the same cubic crystal structure in any substance, and the lattice constant is about 1.22 nm. Therefore, each alum has a high degree of lattice matching, which indicates the degree of matching between the lattice constants of two types of crystals. In addition, since each alum has the same crystal structure, it is assumed that they also have the same binding property and easily function as an anti-supercooling agent.

Therefore, in the present embodiment, by using the second alum, which has a higher melting point than the first alum used as the latent heat storage material 10, as the supercooling prevention agent 21, the supercooling prevention agent 21 is effective against the latent heat storage material 10. It is considered that it became easier to function as a supercooling inhibitor.

(Actions and effects of the latent heat storage material composition of the present embodiment)
Next, functions and effects of the latent heat storage material composition 1 of the present embodiment will be described. The latent heat storage material composition 1 of the present embodiment is mainly composed of a latent heat storage material 10 that stores or releases heat by utilizing the input and output of latent heat accompanying a phase change, and an additive that adjusts the physical properties of the latent heat storage material 10. It is a latent heat storage material composition containing an agent 20 . The latent heat storage material 10 is the first alum. The additive 20 is a supercooling prevention agent 21 that promotes the induction of crystallization of the first alum in the molten state. In this embodiment, the supercooling prevention agent 21 is the second alum having a higher melting point than the first alum.

As a result, crystal nuclei of alum (the latent heat storage material 10) are generated as nuclei necessary for suppressing the supercooling phenomenon of alum. Therefore, the crystallization of the latent heat storage material 10 is induced by the formation of alum crystal nuclei based on the supercooling prevention agent 21, and the latent heat storage material composition 1 is cooled from the melt state to the latent heat storage material 10 It is possible to dissipate the stored latent heat while suppressing the deviation between the melting point and the freezing point.

In particular, in the present embodiment, both the first alum used as the latent heat storage material 10 and the second alum used as the supercooling prevention agent 21 are alums, so that they have the same cubic crystal structure. , and the lattice constants are almost the same. Therefore, the first alum used as the latent heat storage material 10 and the second alum used as the supercooling prevention agent 21 have high lattice matching. Further, since the first alum used as the latent heat storage material 10 and the second alum used as the supercooling prevention agent 21 have the same crystal structure, they also have the same bonding properties. Therefore, the second alum easily functions as the supercooling prevention agent 21 for the latent heat storage material 10 composed of the first alum.

As described above, the supercooling prevention agent 21 composed of the second alum has the same lattice constant and bonding property as the latent heat storage material 10 composed of the first alum. It satisfies the conditions of the supercooling prevention agent for the latent heat storage material 10.

Therefore, according to the latent heat storage material composition 1 of the present embodiment, the latent heat storage material 10 containing alum as a main component is more reliably prevented from overcooling, and the stored latent heat is dissipated. The excellent effect of being able to

In addition, alum has a heat storage capacity approximately double that of paraffin, and is highly nonflammable and safe.

In addition, in the latent heat storage material composition 1 of the present embodiment, the blending ratio of the second alum to the weight of the entire latent heat storage material composition 1 is 10 wt % or less. As a result, in the process of cooling the latent heat storage material composition 1 from the melt state more reliably, the difference between the melting point and the solidification point of the latent heat storage material 10 is suppressed. The supercooling phenomenon in the material 10 can be suppressed.

Further, in the latent heat storage material composition 1 of the present embodiment, the first alum is iron alum dodecahydrate. The second alum is any one of ammonium alum dodecahydrate, potassium alum dodecahydrate, and sodium alum dodecahydrate. In this way, since alum, which is widely distributed in the market and is easy to obtain and inexpensive, is used, it is possible to more reliably suppress the occurrence of the supercooling phenomenon in the latent heat storage material 10 while reducing costs.

In addition, since the latent heat storage material composition 1 of the present embodiment can be used repeatedly in a temperature range in which the supercooling prevention agent 21 is not deactivated, it can be applied, for example, as a heat storage mat in the event of a disaster or as a building material for housing.

It should be noted that the above-described embodiment is merely an example and does not limit the present disclosure in any way, and of course various improvements and modifications are possible without departing from the gist of the present disclosure.

Also, the first alum and the second alum are respectively inorganic salt crystals composed of a double salt of monovalent cation sulfate and trivalent metal ion sulfate. The monovalent cations may be any one of ammonium ions, potassium ions, sodium ions, and rubidium ions. Also, the trivalent metal ion may be any one of iron ion (III), aluminum ion, and chromium ion (III).

For example, with the proviso that the second alum has a higher melting point than the first alum, each of the first alum and the second alum may be any of the following.
(1) Iron alum dodecahydrate (2) Ammonium alum dodecahydrate (3) Potassium alum dodecahydrate (4) Sodium alum dodecahydrate (5) Chromium alum dodecahydrate (Potassium chromium (III) sulfate.12 _- hydrate, CrK( _SO4 ) _2.12H2O , melting point 89°C)
(6) Rubidium alum dodecahydrate (ammonium rubidium sulfate dodecahydrate, _AlRb ( _SO4 ) _2.12H2O , melting point 99°C)

1 latent heat storage material composition 10 latent heat storage material 20 additive 21 supercooling inhibitor T0a temperature T0b temperature T1a temperature T1b temperature time t0a
time t0b
Time t1a
Time t1b

Claims (4)

A latent heat storage material composition containing, as a main component, a latent heat storage material that stores heat or releases heat by utilizing the input and output of latent heat associated with a phase change, and an additive that adjusts the physical properties of the latent heat storage material,
The latent heat storage material is a first alum,
The additive is a supercooling inhibitor that promotes the induction of crystallization of the first alum in a molten state,
The supercooling inhibitor is a second alum having a higher melting point than the first alum,
Each of the first alum and the second alum is an inorganic salt crystal composed of a double salt of a monovalent cation sulfate and a trivalent metal ion sulfate,
the monovalent cation is an ammonium ion, a potassium ion, a sodium ion, or a rubidium ion;
The trivalent metal ion is any one of iron ion (III), aluminum ion, and chromium ion (III);
The first alum is iron alum dodecahydrate (FeNH ₄ (SO ₄ ) _{2.12H 2 O} ),
The second alum is ammonium alum dodecahydrate (AlNH ₄ (SO ₄ ) 2.12H ₂ O), potassium alum dodecahydrate ( _AlK (SO ₄ ) _{2.12H 2} O), sodium alum dodecahydrate ( _AlNa ( _SO4 ) _2.12H2O ),
A latent heat storage material composition characterized by: In the latent heat storage material composition according to claim 1,
the blending ratio of the second alum to the weight of the entire latent heat storage material composition is 10 wt% or less;
A latent heat storage material composition characterized by: A latent heat storage material composition containing, as a main component, a latent heat storage material that stores heat or releases heat by utilizing the input and output of latent heat associated with a phase change, and an additive that adjusts the physical properties of the latent heat storage material,
The latent heat storage material is a first alum,
The additive is a supercooling inhibitor that promotes the induction of crystallization of the first alum in a molten state,
The supercooling inhibitor is a second alum having a higher melting point than the first alum,
the difference between the melting point of the second alum and the melting point of the first alum is 20° C. or more;
the blending ratio of the second alum to the weight of the entire latent heat storage material composition is 10 wt% or less;
A latent heat storage material composition characterized by: In the latent heat storage material composition according to claim 3 ,
Each of the first alum and the second alum is an inorganic salt crystal composed of a double salt of a monovalent cation sulfate and a trivalent metal ion sulfate,
the monovalent cation is an ammonium ion, a potassium ion, a sodium ion, or a rubidium ion;
The trivalent metal ion is any one of iron ion (III), aluminum ion, and chromium ion (III);
A latent heat storage material composition characterized by:

Images