JP2000111282A - Heat storage device and heat control in heat storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat storage device low in heat loss to an external environment and a heat control method in this device. SOLUTION: A heat storage device comprises a heat storage material 1 having a remarkable supercooling phenomenon for storing heat, a heat storage tank 2 filled with the heat storage material 1 and a heat exchanger 4 performing the injection and extraction of heat between the heat storage material 1 and the external part or the heat storage tank 2. In the heat storage device, heat is stored in the heat storage material 1 under a supercooled state lower than a freezing point. Upon extraction of heat, heat discharged in a recovery process of the heat storage material 1 to the temperature of freezing point and a subsequent freezing process is used. Thus, the heat storage material is stored at temperature lower than the temperature upon recovery of heat, so that heat loss to an external environment is decreased during the storage of heat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage device for storing heat for a certain period of time and a heat management method for the device.

[0002]

2. Description of the Related Art The basic structure of a conventional heat storage device is shown in FIG.
FIG. 9 is a cross-sectional view. The heat storage device of FIG. 8 includes a heat storage tank 22 filled with a heat storage material 21 for storing heat, an outer periphery of the heat storage tank 22 surrounded by a heat insulating material 23, and a heat exchanger 24 that performs heat exchange with the outside in the heat storage tank 22. It is provided. In the heat storage device shown in FIG. 9, the outer periphery of the heat storage tank 32 is surrounded by a heat insulating material 33 as in the device of FIG.
5 is stored in the heat storage tank 32, and a communication pipe 36 for communicating the heat storage tank 32 with the outside is provided to constitute a heat exchanger for performing heat exchange with the outside. There are three types of heat storage modes, one using the sensible heat (heat generated by the temperature difference) of the heat storage materials 21 and 31 in the heat storage device as shown in FIGS. Some use heat) and others use chemical reactions. Here, the former two heat storage methods related to the present invention will be described more specifically.

Assuming that the heat storage device has a configuration as shown in FIG. 8 or FIG. 9, first, an operation of a device using sensible heat will be described. Water is often used as the heat storage material using sensible heat. For example, in order to store heat having a temperature of Tx, heat having a temperature of Tx or higher is externally applied to the heat exchanger to increase the temperature of the heat storage material to Tx or higher. When the heat injection is completed, the heat storage device is allowed to stand still. When time elapses and heat is required outside, heat at a temperature of Tx is extracted to the outside from the heat storage material using the heat exchanger. The temperature of the extracted heat decreases over time. When the heat storage material is water, hot water is directly injected into the heat storage tank from outside using the same communication pipe 36 as in FIG. 9 without using a heat exchanger.
In some cases, hot water is directly extracted and used when needed.
In this case, water serves both as a heat exchange medium and a heat storage material.

[0004] Next, the operation of a device utilizing the transition heat will be described. The heat of fusion of water or paraffin is often used as the heat storage material utilizing the transition heat. For example, to store heat having a temperature of Tc, a substance having a freezing point equal to or higher than Tc is used as a heat storage material. The temperature from the outside to the heat exchanger is the melting point Ta of the heat storage material.
When the above heat is applied, the temperature of the heat storage material rises to Ta, and at that temperature, the heat storage material melts from a solid to a liquid. In the melting process, the heat of the heat storage material is kept at Ta because all the heat given from the outside is absorbed as the latent heat of fusion. When the melting of the heat storage material is completed and all the solids are changed to liquid, the temperature of the heat storage material rises again to the temperature of the heat applied from the outside.
When the heat injection is completed, the heat storage device is allowed to stand still. When time elapses and external heat is required, heat is extracted from the heat storage material using a heat exchanger. The temperature of the heat storage material is T at the freezing point
When it drops to c, it solidifies from a liquid to a solid. The solidification process is the reverse of the melting process, and all the heat released to the outside is the heat of solidification (equal to the heat of fusion).
Is kept. When the solidification of the heat storage material is completed and the liquid is completely changed to a solid, the temperature of the heat storage material falls again in accordance with heat extraction to the outside. When water is used as the heat storage material, it is used for storing cold heat as an ice heat storage device using the melting point of water.

A heat storage device of the type shown in FIG.
The heat is injected and extracted by passing the fluid from outside to the heat storage tank 32 using the heat pump 6. Since the fluid from the outside passes through the gap around the small container 35, the heat storage material 3
1 is mainly used for a heat storage device utilizing transition heat, since the heat transfer area for the heat transfer material 1 is large and the handling of the heat storage material 31 is easy. However, only the heat exchange method is different. Is similar to that of FIG.

[0006]

In the heat storage device as shown in FIGS. 8 and 9, if there is a temperature difference between the heat storage tank and the environment surrounding the heat storage tank, there is always a heat between the heat storage tank and the outside. Movement occurs, and the heat loss Ql of the heat storage tank becomes

(Equation 1) It is represented by The effects of thermal radiation are usually ignored because they are small. k is the heat transfer rate determined by the material and structure of the heat storage tank and the heat insulating material, the surrounding wind speed, and the like, and A is the contact area between the heat storage tank and the surrounding fluid (for example, air). To is the temperature around the heat storage tank, T
x is the temperature of the heat storage material at the surface where the heat storage material contacts the heat storage tank. t is the elapsed time. Since k and A can usually be regarded as constant regardless of time, equation (1) can be approximated as follows.

(Equation 2)

In the conventional heat storage device, whether the sensible heat is used or the transition heat is used as described above,
For example, in order to store heat at the temperature Tx, it is necessary to maintain the heat storage material at a temperature equal to or higher than Tx. Therefore, as the storage temperature becomes higher and the storage time becomes longer, the heat loss represented by the formula (2) increases, which causes the heat storage efficiency to decrease. From the equation (2), in order to reduce the heat loss from the heat storage tank, the heat transmittance k and the surface area A are reduced, and the time t
Or the difference between the heat storage temperature Tx and the ambient temperature To must be reduced. As a method for reducing the heat transfer rate k, an attempt has been made to improve the heat insulating material. As a method for reducing the surface area, an attempt has been made to make the heat storage tank a shape like a cube or a sphere. As a method of reducing the time t and a method of reducing the difference between the heat storage temperature Tx and the environmental temperature To, optimization of system control of a heat utilization system after re-extraction of heat has been attempted. The term and the temperature term are the primary purpose of heat storage and are not of the nature that can be changed significantly.

The present invention has been made to improve the heat loss from the heat storage material as described above. The heat storage material is stored at a temperature lower than the temperature required at the time of heat extraction, and is discharged from the heat storage material to the outside. An object of the present invention is to provide a heat storage device in which heat loss due to heat dissipation is reduced and a heat management method in the device.

[0009]

A heat management method in a heat storage device according to the present invention for achieving the above object comprises a supercoolable heat storage material for storing given heat, and a heat storage material filled with the heat storage material. In a heat storage device comprising a tank and heat exchange means for injecting and extracting heat between the heat storage material and the outside of the heat storage tank, the heat storage material stores heat in a supercooled state lower than a freezing point. In extracting heat, the heat released from the heat storage material to the freezing point temperature and the heat released during the subsequent solidification process is used. Further, a heat storage device of the present invention for carrying out the above heat management method includes a heat storage material capable of supercooling for storing given heat, a heat storage tank filled with the heat storage material, the heat storage material and the heat storage material. And a heat exchange means for injecting and extracting heat to and from the outside of the tank.

[0010] The heat storage tank is provided with means for maintaining the temperature of the heat storage material so as not to drop below a certain value.
A means for partially cooling the temperature of the heat storage material is provided,
Means for disturbing the heat storage material can be provided.

[0011]

Before describing the operation of the heat storage device having the above-described structure and the heat management method in the device, first, the characteristics of the heat storage material in melting and solidification will be described. FIG. 6 shows a state of a temperature change when the substance is melted and solidified. The horizontal axis indicates the elapsed time when the substance is heated and cooled at a constant rate, and the vertical axis indicates the temperature of the substance. . When a substance that is initially solid is heated, the kinetic energy of the substance molecules increases due to the injected heat until time A, so that the temperature of the substance increases. Upon reaching time A, which is the melting point Ta of the substance, the substance begins to melt. The temperature of the substance in the melting process has a constant value Ta because all the injected heat is consumed for increasing the potential energy between molecules. When the melting is completed and time B is reached, the temperature of the liquid substance is increased again and stored as sensible heat. Thereafter, when the substance is cooled, the kinetic energy of the substance molecules is reduced and the temperature is lowered. When the temperature reaches the freezing point Tc of the substance at time C, the substance starts to solidify. The temperature of the substance in the coagulation process has a constant value Tc because all the released heat is supplied by the reduction of the potential energy between the molecules. When the solidification is completed and time E is reached, the temperature of the solidified substance falls again and sensible heat is released. In the case of a pure substance, the melting point and the freezing point have the same value, but the freezing point is lower than the melting point if impurities are included.

By the way, in reality, solidification often does not start even when the temperature of the substance reaches the solidification point. When the material in the liquid state is cooled slowly and slowly, the temperature of the material falls, and when the freezing point Tc of the material at time C is reached, the material should ideally start to solidify. FIG. 7 shows that the molecules of the substance do not immediately orient themselves to fit well into the crystal lattice,
As shown in FIG. When the temperature of the substance drops to a certain value (in FIG. 7, a temperature lower by Ts than Tc) and reaches time D, some molecules are finally oriented to form a fine crystal. As a result, another molecule is oriented around the center, and as a result, the crystal grows rapidly. That is, coagulation is started.
In the solidification process, potential energy held as a liquid is released, so that the kinetic energy of the substance increases, and the temperature of the substance returns to the freezing point Tc. The substance that has started to solidify undergoes a phase change from a liquid to a solid at a certain temperature, that is, the solidification point Tc. From time E when the solidification is completed, the temperature of the solidified substance falls again, and sensible heat is released. Go being.
The liquid metastable state from time C to time D is called a supercooled state.

The basic operation of the heat storage device is the repetition of three steps of heat injection, storage and extraction. A supercoolable heat storage material for storing given heat, a heat storage tank filled with the heat storage material, and heat exchange means for injecting and extracting heat between the heat storage material and the outside of the heat storage tank are provided. In the heat storage device of the present invention, first, in the heat injection process, the heat storage material filled in the heat storage tank is heated and melted at a temperature equal to or higher than its melting point. In the preservation process, since heat is transferred from the heat storage material to the environment through the heat storage tank, the temperature of the heat storage material gradually decreases. Even if the temperature of the heat storage material reaches the freezing point, the solidification does not start due to the supercooling phenomenon, so that the liquid can be kept as a liquid at a temperature lower than the freezing point. The temperature of the heat storage material is the recrystallization temperature (T
As long as it is higher than c- [Delta] Ts), this supercooled state is maintained. In the heat extraction process, first, the temperature of a part of the heat storage material is lowered to the recrystallization temperature to induce solidification, and when the solidification is started and the temperature of the heat storage material recovers to the freezing point or near the freezing point, the heat is released. Heat is extracted from the heat storage tank by an exchanger or the like. Only a small portion of the heat storage material is sufficient to reduce the heat storage material to the recrystallization temperature. This is because, even if the remaining heat storage material does not drop to the recrystallization temperature, most of the remaining recrystallization proceeds with the generated part of the crystal as the center (nucleus) as described above.

The means for maintaining the heat storage material provided in the heat storage tank so as not to drop below a certain temperature acts so that the temperature of the heat storage material does not drop to the recrystallization temperature. For this reason, even if the heat storage period and the environmental temperature fluctuate unexpectedly due to disturbance, unnecessary recrystallization can be avoided.

The means for partially cooling the temperature of the heat storage material provided in the heat storage tank cools a part of the temperature of the heat storage material in a supercooled state to a recrystallization temperature to induce recrystallization. Work on. This eliminates the need to lower the temperature of the heat storage material to the recrystallization temperature by using a large heat exchanger wrapped around the entire heat storage material when shifting from heat storage to the extraction process, resulting in less heat loss Can recover heat. This is because, as described above, most of the heat storage materials do not drop to the recrystallization temperature, but recrystallization progresses centering on the crystals generated partially.

Further, the means for disturbing the heat storage material provided in the heat storage tank serves to forcibly change the position of some of the molecules of the heat storage material in a supercooled state and to induce recrystallization.
For this reason, it is not necessary to lower the temperature of a part of the heat storage material to the recrystallization temperature immediately before heat extraction, so that heat can be recovered with less heat loss, and a heat source for lowering the temperature to the recrystallization temperature is required. It becomes unnecessary.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a first embodiment of the heat storage device according to the present invention. In the first embodiment, as the heat storage material 1, various substances can be selected and used according to the required temperature and the degree of supercooling from the substances in which the supercooling phenomenon is remarkable. The degree of supercooling is, for example,
Disodium hydrogen phosphate dodecahydrate (Na ₂ HPO ₄
・ 12H ₂ O) has a freezing point of about 309K (36 ℃)
At a recrystallization temperature of about 296 K (23 ° C.) or sodium acetate trihydrate (CH ₃ COOHNa).
3H ₂ O) has a freezing point of about 331K (58 ° C)
It is known that the recrystallization temperature is about 250K (−23 ° C.). In addition to these materials, examples of the substance which has a remarkable supercooling phenomenon suitable for use as the heat storage material 1 include, for example, sodium sulfate decahydrate (Na ₂ SO ₄ .10H).
₂ O), sodium carbonate decahydrate (Na ₂ CO ₃ · 10
H ₂ O), sodium thiosulfate pentahydrate (Na ₂ S ₂ O)
₃ · 5H ₂ O), magnesium chloride hexahydrate (MgCl
₂ · 6H ₂ O), aluminum sulfate decahydrate (Al ₂
(SO ₄ ) ₃ .10H ₂ O), magnesium nitrate hexahydrate (Mg (NO ₃ ) ₂ .6H ₂ O), aluminum ammonium sulfate dodecahydrate (NH ₄ Al (SO ₄ ) ₂ .1)
2H ₂ O), potassium aluminum sulfate dodecahydrate (K
Al (SO ₄ ) ₂ .12H ₂ O), nickel nitrate (II)
Hexahydrate (Ni (NO ₃ ) ₂ .6H ₂ O), calcium chloride hexahydrate (CaCl ₂ .6H ₂ O), calcium carbonate hexahydrate (CaCO ₃ .6H ₂ O), and fluoride Examples thereof include potassium tetrahydrate (KF.4H ₂ O), but are not limited thereto.

In FIG. 1, the heat storage material 1 is stored in a heat storage tank 2.
The heat storage tank 2 is surrounded by a heat insulating material 3 and a heat exchanger 4 for exchanging heat with the outside is provided in the heat storage tank 2.
The material and shape of the heat storage tank 2 are not limited as long as it is stable with respect to the heat storage material 1. The heat insulating material 3 is a heat storage tank 2
The material and shape are not limited as long as the material and the environment surrounding the heat insulating material are stable. In addition, heat exchanger 4
Is not limited as long as it has stability with respect to the heat storage material 1. However, the heat storage tank 2 and the heat insulating material 3
It is desired that the heat storage material 1 be designed so that the temperature does not fall below the recrystallization temperature during the storage period.

Next, the operation of the heat storage device of the first embodiment will be described. First, in the heat injection process, the heat exchanger 4
Is used to heat the heat storage material 1 filled in the heat storage tank 2 at a temperature equal to or higher than the melting point of the heat storage material 1 to melt from a solid to a liquid.
In the preservation process, since heat moves from the heat storage material 1 to the external environment through the heat storage tank 2 and the heat insulating material 3, the temperature of the heat storage material 1 gradually decreases. The temperature of the heat storage material 1 eventually reaches the solidification point, but solidification is not started due to a supercooling phenomenon. The temperature of the heat storage material 1 further decreases to a temperature lower than the freezing point, but can remain as a liquid. If the shape of the heat storage tank 2 and the heat insulating material 3 are designed so that the temperature of the heat storage material 1 does not fall below the recrystallization temperature during the storage period, even if the temperature of the heat storage material 1 falls below the freezing point, the recrystallization will occur during the storage period. It does not change. Normally, during most of the storage period, the temperature of the heat storage material is lower than the freezing point. Therefore, compared with the conventional heat storage tank which always maintains the temperature at a temperature higher than the freezing point, the relationship between the heat storage material and the environment in the equation (2) is obtained. And the heat loss Ql from the heat storage material 1 to the environment can be reduced.

In the extraction process, first, the heat exchanger 4 is used to lower the temperature of a part of the heat storage material 1 to the recrystallization temperature to induce solidification. Only a small amount of the heat storage material 1 near the heat exchanger 4 suffices for the amount of the heat storage material 1 to be lowered to the recrystallization temperature. This is because, as described above, even if the temperature of the remaining heat storage material does not drop to the recrystallization temperature, the generated microcrystals serve as nuclei, and the crystallization motion spreads throughout the heat storage material 1. . When the solidification is started, the temperature of the heat storage material is restored to the freezing point or near the freezing point by the stored heat of fusion. Can be extracted.

As described above, the heat storage material, the heat storage tank, and the heat exchange means can have any shape and configuration. For example,
As a form corresponding to FIG. 9 of the conventional example, it is also possible to adopt a configuration like the second embodiment illustrated in FIG. In the heat storage device of FIG. 2, the outer periphery of the heat storage tank 12 is surrounded by a heat insulating material 13, but the heat storage material 11 is filled in a small container 15 and stored in the heat storage tank 12. A communication pipe 16 for communication is provided to constitute a heat exchanger for exchanging heat with the outside. The material and shape of the small container 15 are not limited as long as it is stable with respect to the fluid circulating in the heat storage material 11 and the heat storage tank 12. The material and shape of the communication pipe 16 are not limited as long as the communication pipe 16 is stable with respect to the fluid passing through the inside of the communication pipe 16 and the environment surrounding the communication pipe 16.

The operation of the second embodiment is basically the same as that of the first embodiment. That is, in the heat injection process, a fluid having a temperature equal to or higher than the melting point of the heat storage material 11 is passed through the communication pipe 16 to the gap between the small containers 15 in the heat storage tank 12,
The heat storage material 11 filled in each small container 15 is melted. In the preservation process, the heat storage material 11 and the small container 15 and the heat storage tank 12,
Although the heat is transferred to the external environment through the heat insulating material 13, the temperature of the heat storage material 11 gradually decreases. However, the heat storage material 11 is in a liquid state even at a temperature lower than the freezing point of the heat storage material 11 due to the supercooling phenomenon as described above. Saved as is. That is, as compared with the conventional heat storage device, the temperature difference between the heat storage material and the environment in Expression (2) can be reduced, and the heat loss Ql from the heat storage tank 12 to the environment can be reduced. In the extraction process, first, the temperature of a part of the heat storage material 11 is reduced to the recrystallization temperature by using the communication pipe 16 to induce solidification. As for the amount of the heat storage material 11 to be lowered to the recrystallization temperature, only a small amount of the heat storage material 11 near the inlet from the communication pipe 16 to the heat storage tank 12 is sufficient. When coagulation starts,
Since the temperature of the heat storage material is restored to the freezing point or near the freezing point by the stored heat of fusion, it is possible to use the communication pipe 16 to recover the heat of the heat storage material 11 at the freezing point or a temperature close to the freezing point from the heat storage tank 12. it can.

FIG. 3 shows a modification of the heat storage device according to the first embodiment of the present invention. That is, the first of FIG.
In the embodiment, as means for maintaining the temperature of the heat storage material 1 in the heat storage tank 2 so as not to drop below a certain value, a heater 7
Is provided. The heater 7 generates heat directly in the heat storage tank 2 like an electric heater, or injects heat generated outside the heat storage tank 2 like a heat exchanger. Alternatively, a thermoelectric element (Peltier element) may be used to statically transport external heat into the heat storage tank 2 by applying a voltage, and the heat generation principle and structure are not limited.

Next, the operation of the heat storage device of FIG. 3 will be described. It is clear from the above equation (2) that the heat loss from the heat storage material 1 to the external environment increases as the heat storage period increases or as the environmental temperature decreases. As the heat loss of the heat storage material increases, the temperature of the heat storage material will decrease significantly. In the apparatus of FIG. 3, when the designed heat storage period and the environmental temperature fluctuate for some reason during storage and the temperature of the heat storage material is expected to be lower than the recrystallization temperature, the temperature of the heat storage material is changed to the recrystallization temperature. Heater 7 so as not to fall below
To work. This makes it possible to provide a heat storage device that is not affected by changes in the heat utilization state or environment. The configuration and operation principle of the present embodiment other than those described above are the same as those of the first embodiment, and a description thereof will be omitted.

FIG. 4 shows another modification of the heat storage device of the first embodiment of the present invention. That is, in the first embodiment shown in FIG. 1, a cooler 8 for lowering the temperature of the heat storage material 1 below the recrystallization temperature is provided in the heat storage tank 2 as means for partially cooling the heat storage material 1. The cooler 8 can release the heat of the heat storage tank 2 to the outside by applying a voltage like a thermoelectric element, but can also use the heat storage tank 2 like a heat exchanger.
The cooling heat generated outside may be injected, and the cooling principle and structure are not limited.

Next, the operation of the heat storage device of FIG. 4 will be described. In the first embodiment, when shifting from the heat storage to the extraction process, the heat exchanger 4 is used to lower the temperature of a part of the heat storage material 1 to the recrystallization temperature to induce solidification. But,
In general, the heat exchanger 4 is stretched around the entire inside of the heat storage tank 2 to promote heat transfer. To cool the heat storage material 1 using the heat exchanger 4 requires the temperature of the heat storage material 1. There is also the possibility of lowering it. Further, as mentioned above,
Only a small amount of the heat storage material 1 to be lowered to the recrystallization temperature is sufficient. Therefore, in the apparatus of FIG. 4, cooling for promoting recrystallization performed at the time of extracting heat is performed by the minute cooler 8. Thereby, the temperature of the heat storage material is not unnecessarily lowered to the recrystallization temperature, and a heat storage device that recovers heat with less heat loss can be provided. The configuration and operation principle of the present embodiment other than the above are as follows.
Since it is the same as that of the first embodiment, the description thereof is omitted.

Further, as described in the embodiment of FIG. 3, a heater 7 for maintaining the temperature of the heat storage material 1 so as not to fall below a certain value is added to the present embodiment. It is possible to obtain a heat storage device that does not unnecessarily lower the temperature of the material 1 to the recrystallization temperature and is not influenced by a heat utilization state or a change in environment.

FIG. 5 shows another modification of the heat storage device of the first embodiment of the present invention. That is, in the first embodiment of FIG. 1, the heat storage tank 2 is provided with a disturbance device 9 as a means for disturbing the heat storage material 1. This disturbance 9
A part of the molecules of the heat storage material 1 is forcibly changed from the outside to induce recrystallization, and it uses stirring by a stirrer, vibration by a vibrator, squeezing or collision by a slider, etc. can do. Various methods can be employed for the stirring method, the vibration method, the squeezing method, and the collision method. For example, when the vibration is applied, even if the vibration directly occurs in the heat storage tank 2 like a piezoelectric element, the vibration generated outside the heat storage tank 2 is transmitted to the inside of the heat storage tank 2 like an electric vibrator. The vibration principle and structure are not limited.

Next, the operation of the heat storage device of FIG. 5 will be described. In the heat extraction process, in the first embodiment, the heat exchanger 4 is used to lower the temperature of a part of the heat storage material 1 to the recrystallization temperature to induce solidification, but the apparatus shown in FIG. Is caused by forcibly changing the position of some of the molecules of the heat storage material 1 from the outside. When the molecules of the heat storage material 1 are disturbed from the outside, the metastable state of supercooling is broken, nuclei are generated, and crystallization starts. Thus, the temperature of the heat storage material 1 is not lowered to the recrystallization temperature, and a heat storage device that recovers heat with a smaller heat loss can be provided. The configuration and operation principle of the present embodiment other than those described above are the same as those of the first embodiment, and a description thereof will be omitted.

Further, as described in the embodiment of FIG. 3, a heater 7 for maintaining the temperature of the heat storage material 1 so as not to fall below a certain value is added to the present embodiment. By lowering the temperature of the material 1 to the recrystallization temperature, recrystallization can be started without losing heat, and a heat storage device that is not affected by a heat utilization state or an environmental change can be obtained. Furthermore, as described in the embodiment of FIG. 4, if a cooler 8 for lowering the temperature of the heat storage material 1 partially below the recrystallization temperature is added to this embodiment, the heat storage material by the agitator may be unexpectedly provided. Even if the recrystallization of 1 becomes difficult, the recrystallization can be reliably started in the cooler 8, so that it is possible to obtain a heat storage device that more reliably recovers heat with a small heat loss.

[0031]

According to the present invention described in detail above, it is possible to extract heat at the freezing point or near the freezing point of the heat storage material during the heat extraction process. On the other hand, in the heat preservation process, since the heat storage material is stored at a low temperature in a supercooled state below the freezing point, the temperature difference between the heat storage material and the environment in the equation (2) is smaller than that of the conventional heat storage tank. Can be reduced, and the heat loss Ql from the heat storage tank to the environment can be reduced.

By the way, in the heat storage device according to the present invention, the heat storage material goes below its freezing point in the heat storage process, and the heat storage material recovers from the supercooled state to the freezing point of the heat storage material in the heat extraction process. . Since the heat at that time is supplied as a part of the stored heat of fusion, the heat loss through the entire process may be larger than that of the conventional heat storage device. For example, let us consider a case where the heat having the temperature Tc and the heat quantity Qc is stored for a length of time t. Here, the heat storage material of the heat storage device of the present invention and the heat storage material of the conventional heat storage device have the same physical property values except for the presence or absence of the supercooling phenomenon, and the specifications other than the heat storage material are the same, and the environmental temperature is It is assumed that the constant temperature To is 10 ° C. lower than Tc. Further, both heat storage materials are stored at a temperature higher than the recrystallization temperature of the heat storage material of the present invention.

In this case, the amount of heat stored by the conventional heat storage device at time t is as follows: Qo = Qc-Qlc (3) Here, Qlc is a heat loss represented by the equation (2). On the other hand, the amount of heat stored by the heat storage device of the present invention at the time t is: Qn = Qc−2Qlh (4) Here, Qlh is the heat loss represented by the equation (2). The loss is doubled because the same amount of heat as the heat loss released to the outside during storage is required in order for the temperature of the heat storage material to return to the freezing point after the recrystallization is started.
Here, in order to simplify the calculation, it is assumed that the heat storage material of the conventional heat storage device does not complete solidification even at time t.
In addition, it is assumed that both heat storage materials have a volume of 1 m ³ , both heat storage tanks have a rectangular parallelepiped shape, and a heat transmission rate described in equation (2) is 0.3 W / m ² K. At this time, since the surface area of both heat storage tanks is about 6 m ² ,
From equation (2), Qlc = 1.8 (Tc−To) t = 18t (5)

Even if the temperature of the heat storage material of the present invention becomes lower than the freezing point, solidification does not start and no heat of fusion is released, so that the temperature is lowered by heat release to the external environment through the heat storage tank. In order to simplify the calculation, it is assumed that the recrystallization temperature of the heat storage material is lower than the environmental temperature To, and that the temperature of the heat storage material decreases to approximately the environmental temperature by time t.
The heat storage material remains completely liquid even at time t, and the heat loss released to the environment by that time is equal to the sensible heat lost by the heat storage material. That is, Qlh = MC (Tc-To) = 10MC (6) Here, M is the mass of the heat storage material, and C is the constant pressure specific heat of the heat storage material. For example, when the heat storage material is the above disodium hydrogen phosphate dodecahydrate, the heat of fusion that can be stored in 1 m ³ is about 550 MJ, and 2Qlh of the formula (4)
Is about 100 MJ. The time t required for the same amount of heat as 2Qlh to be radiated from the conventional heat storage device at the freezing point Tc is 5.56 million seconds (64 days) from equation (5).
It can be seen that it is. That is, the heat loss of the conventional heat storage device is smaller within a certain boundary period (for example, 64 days in the case of the above assumption), but the heat storage device of the present invention is longer in the longer period. It can be seen that the heat loss throughout the entire period is smaller. Therefore, the heat storage device of the present invention has a heat storage period of 3 to 6 such as natural energy.
It has a particularly good effect on heat storage objects that last for months.

Further, the heat storage device of the present invention can cause the heat storage material to be freely recrystallized by the heat exchanger. Therefore, it can be configured with equipment having the same structure as the conventional heat storage device. Moreover, by providing the heater in the heat storage tank, it is possible to prevent the temperature of the heat storage material from dropping to the recrystallization temperature, and even if the heat storage period and the environmental temperature fluctuate unexpectedly due to disturbance, unnecessary Recrystallization can be avoided. Alternatively, by providing a cooler in the heat storage tank, the temperature of the heat storage material in the supercooled state can be partially cooled to the recrystallization temperature, and recrystallization can be induced. It is not necessary to lower the temperature of the heat storage material to the recrystallization temperature by using a large heat exchanger spread over the entire material, so that heat can be recovered with less heat loss. Alternatively, by providing an agitator in the heat storage tank, the molecules of the heat storage material in a supercooled state can be disturbed and recrystallization can be induced, so that the temperature of a part of the heat storage material is reset during heat extraction. There is no need to lower the temperature to the crystallization temperature, heat can be recovered with less heat loss, and a heat source for lowering the heat storage material to the recrystallization temperature becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a heat storage device according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the heat storage device according to the present invention.

FIG. 3 is a sectional view showing a modification of the heat storage device according to the present invention.

FIG. 4 is a sectional view showing another modified example of the heat storage device according to the present invention.

FIG. 5 is a sectional view showing another modified example of the heat storage device according to the present invention.

FIG. 6 is an explanatory diagram of a transition phenomenon.

FIG. 7 is an explanatory diagram of a transition phenomenon accompanied by supercooling.

FIG. 8 is a cross-sectional view of a conventional heat storage device.

FIG. 9 is a sectional view of another conventional heat storage device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,11 Heat storage material 2,12 Heat storage tank 3,13 Heat insulation material 4 Heat exchanger 7 Heater 8 Cooler 9 Disturber 15 Small container 16 Communication pipe

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[Procedure amendment]

[Submission Date] June 28, 1999 (1999.6.2
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009]

A heat management method in a heat storage device according to the present invention for achieving the above object comprises a supercoolable heat storage material for storing given heat, and a heat storage material filled with the heat storage material. and so, in the thermal storage apparatus and a heat exchange means for performing injection and extraction of heat between the outside of the heat storage tank and the heat storage material, the heat with the storage at a supercooled state below the freezing point to the heat storage material The temperature of the heat storage material does not drop below a certain value
The method is characterized in that the heat is extracted and the heat released during the solidification process is used for the recovery of the heat storage material to the freezing point temperature and for the subsequent heat extraction. In addition, the heat storage device of the present invention for performing the heat management method includes a supercoolable heat storage material that stores given heat, a heat storage tank filled with the heat storage material, and a temperature of the heat storage material. Than a certain value
It is characterized by comprising a heating means for keeping the temperature of the heat storage material from falling, and a heat exchange means for injecting and extracting heat between the heat storage material and the outside of the heat storage tank.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

The heat storage tank partially stores the temperature of the heat storage material.
A means for cooling is provided, and a means for disturbing the heat storage material is provided.
Can be provided.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Embodiments will be described in detail. FIG.Assumption of the present invention
Become1 shows a first embodiment of a heat storage device. This first implementation
In the example, the heat storage material 1 is a material having a remarkable supercooling phenomenon.
Various materials depending on the required temperature and degree of supercooling from the quality
Quality can be selected and used. Degree of supercooling is an example
For example, disodium hydrogen phosphate dodecahydrate (Na₂ 
HPO₄ ・ 12H₂ In O), its freezing point is about 309K
(36 ° C) and the recrystallization temperature is about 296K (23 ° C)
Or sodium acetate trihydrate (CH₃ 
COOHNa 3H₂ In O), its freezing point is about 331
K (58 ° C), recrystallization temperature 250K (-23 ° C)
It is known to be about. In addition to these,
A substance with a remarkable supercooling phenomenon suitable for use as heat material 1
As, for example, sodium sulfate decahydrate (Na₂ 
SO₄ ・ 10H₂ O), sodium carbonate decahydrate (N
a₂ CO₃ ・ 10H₂ O), sodium thiosulfate
Hydrate (Na₂ S₂O₃ ・ 5H₂ O) 、 Magnesium chloride
Cium hexahydrate (MgCl₂ ・ 6H₂ O), Al sulfate
Minium decahydrate (Al₂ (SO₄ )₃ ・ 10H₂ 
O), magnesium nitrate hexahydrate (Mg (NO₃)₂ 
・ 6H₂ O), Aluminum ammonium sulphate decahydrate
Japanese (NH₄ Al (SO₄ )₂ ・ 12H₂ O), sulfuric acid
Potassium aluminum phosphate dodecahydrate (KAl (SO
₄ )₂ ・ 12H₂ O), nickel (II) nitrate hexahydrate
Object (Ni (NO ₃ )₂ ・ 6H₂ O), calcium chloride
Hexahydrate (CaCl₂ ・ 6H₂ O), calcium carbonate
Hexahydrate (CaCO₃ ・ 6H₂ O), and fluoride
Potassium tetrahydrate (KF-4H₂ O)
However, the present invention is not limited to these.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

As described above, the heat storage material, the heat storage tank, and the heat exchange means can have any shape and configuration. For example,
As forms corresponding to Figure 9 of the prior art, the present illustrated in FIG. 2
It is also possible to adopt a configuration as in the second embodiment , which is a premise of the invention . In the heat storage device of FIG. 2, the outer periphery of the heat storage tank 12 is surrounded by a heat insulating material 13, but the heat storage material 11 is filled in a small container 15 and stored in the heat storage tank 12.
There is provided a communication pipe 16 for communicating between the outside and the outside to constitute a heat exchanger for performing heat exchange with the outside. Small container 15
The material and the shape are not limited as long as it is stable against the fluid circulating in the heat storage material 11 and the heat storage tank 12. The material and shape of the communication pipe 16 are not limited as long as the communication pipe 16 is stable with respect to the fluid passing through the inside of the communication pipe 16 and the environment surrounding the communication pipe 16.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0023

[Correction method] Change

[Correction contents]

FIG. 3 shows a typical example of the heat storage device of the present invention .
ing. That is, in the first embodiment shown in FIG. 1, a heater 7 is provided in the heat storage tank 2 as means for maintaining the temperature of the heat storage material 1 so as not to drop below a certain value. The heater 7 generates heat directly in the heat storage tank 2 like an electric heater, or injects heat generated outside the heat storage tank 2 like a heat exchanger. Alternatively, a thermoelectric element (Peltier element) may be used to statically transport external heat into the heat storage tank 2 by applying a voltage,
The heat generation principle and structure are not limited.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

FIG. 4 shows another modification of the heat storage device of the first embodiment , which is a premise of the present invention . That is, in the first embodiment shown in FIG. 1, a cooler 8 for lowering the temperature of the heat storage material 1 below the recrystallization temperature is provided in the heat storage tank 2 as means for partially cooling the heat storage material 1. This cooler 8
Is for injecting cold generated outside the heat storage tank 2 like a heat exchanger, even if the heat of the heat storage tank 2 is released to the outside by application of a voltage like a thermoelectric element. The cooling principle and structure are not limited.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

Further, the above means have been described in the embodiment of FIG.
In the present invention, the temperature of the heat storage material 1 is not lowered below a certain value.
If the heat storage material 1 is added to the heater 7 for maintaining the temperature, the temperature of the heat storage material 1 is not unnecessarily lowered to the recrystallization temperature during the heat extraction process, and the heat storage is not affected by the heat utilization state or environmental change. A device can be obtained.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

FIG. 5 shows another modification of the heat storage device of the first embodiment which is a premise of the present invention . That is, in the first embodiment of FIG. 1, the heat storage tank 2 is provided with a disturbance device 9 as a means for disturbing the heat storage material 1. This disturbance 9
Is forcibly changing the position of some of the molecules of the heat storage material 1 from the outside to induce recrystallization, such as stirring by a stirrer, vibration by a vibrator, squeezing or collision by a slider, etc. Can be used. Various methods can be employed for the stirring method, the vibration method, the squeezing method, and the collision method. For example, when the vibration is applied, even if the vibration directly occurs in the heat storage tank 2 like a piezoelectric element, the vibration generated outside the heat storage tank 2 is transmitted to the inside of the heat storage tank 2 like an electric vibrator. The vibration principle and structure are not limited.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

The above means have been described in the embodiment of FIG.
In the present invention, the temperature of the heat storage material 1 is not lowered below a certain value.
If the heat storage material 1 is added to the heater 7 to maintain the temperature, the temperature of the heat storage material 1 can be lowered to the recrystallization temperature during the heat extraction process, so that recrystallization can be started without losing heat, and It is possible to obtain a heat storage device that is not affected by changes in state or environment. Furthermore, as described in the embodiment of FIG. 4, if a cooler 8 for lowering the temperature of the heat storage material 1 partially below the recrystallization temperature is added to this embodiment, the heat storage material by the agitator may be unexpectedly provided. Even if the recrystallization of 1 becomes difficult, the cooler 8
Thus, the recrystallization can be reliably started, so that it is possible to obtain a heat storage device that recovers heat with less heat loss.

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a heat storage device as a premise of the present invention .

FIG. 2 is a sectional view showing a second embodiment of the heat storage device on which the present invention is based .

FIG. 3 is a sectional view showing an example of a heat storage device of the present invention.

FIG. 4 is a sectional view showing another modified example of the heat storage device according to the present invention.

FIG. 5 is a sectional view showing another modified example of the heat storage device according to the present invention.

FIG. 6 is an explanatory diagram of a transition phenomenon.

FIG. 7 is an explanatory diagram of a transition phenomenon accompanied by supercooling.

FIG. 8 is a cross-sectional view of a conventional heat storage device.

FIG. 9 is a sectional view of another conventional heat storage device.

[Description of Signs] 1,11 Heat storage material 2,12 Heat storage tank 3,13 Heat insulation material 4, Heat exchanger 7 Heater 8 Cooler 9 Disturber 15 Small vessel 16 Communication pipe

Claims (5)

[Claims] 1. A supercoolable heat storage material for storing given heat, a heat storage tank filled with the heat storage material, and injection and extraction of heat between the heat storage material and the outside of the heat storage tank. In the heat storage device provided with a heat exchange means, the heat storage material stores heat in a supercooled state lower than the freezing point, and when the heat is extracted, the heat storage material is recovered to the freezing point temperature and released in the subsequent freezing process. A method for managing heat in a heat storage device, characterized in that heat is used. 2. An apparatus for carrying out the method according to claim 1, wherein the heat storage material is a subcoolable heat storage material for storing given heat, the heat storage tank filled with the heat storage material, and the heat storage material. A heat storage device comprising: heat exchange means for injecting and extracting heat between a material and the outside of the heat storage tank. 3. The heat storage device according to claim 2, wherein the heat storage tank is provided with means for maintaining the temperature of the heat storage material so as not to drop below a certain value. 4. The heat storage device according to claim 2, wherein the heat storage tank is provided with a means for partially cooling the heat storage material. 5. The heat storage device according to claim 2, wherein the heat storage tank is provided with a means for disturbing the heat storage material.