JPH08320137A - Heat accumulating system - Google Patents

Abstract

PURPOSE: To reduce an installing space and a facility expenditure and to increase a heat accumulating amount in a cold water heat accumulating tank by a method wherein water at a high temperature side in a cold water heat accumulating tank is mixed with water in an ice heat accumulation tank during heat accumulating operation, water in the ice heat accumulating tank after its thermal radiation is supplied into a cold water heat accumulating tank and a water surface in the ice heat accumulating tank and a water surface of the ice heat accumulating tank are set to be equal in level. CONSTITUTION: During a heat accumulating operation, a valve 23 in a circuit 21 is opened, water taken from a high temperature side of a cold water heat accumulating tank 2, i.e., an upper end of the cold water heat accumulating tank 2 is supplied to a suction side of a pump 7 in a circuit 4 and mixed with water taken out of an ice heat accumulating tank 1. In the case that a heat radiating operation is carried out under a state in which ice is generated within the ice heat accumulating tank 1 and cold water of 0 deg.C is accumulated in the cold water heat accumulating tank 2, either a part of or whole of water of which temperature is increased is taken out to a circuit 22 when the water is returned back to the upper part of the ice heat accumulating tank 1 and further the water is returned back to the high temperature side (the upper part of the tank) of the cold water heat accumulating tank 2. Then, the water in the ice heat accumulating tank 1 is supplied to a low temperature side (a lower part of the tank) in the cold water heat accumulating tank 1 through a circuit 3 in such a manner that a water surface level of the ice heat accumulating tank 1 and a water surface level of the cold heat accumulating tank 2 may become equal to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage system having both an ice heat storage tank and a cold water heat storage tank.

[0002]

2. Description of the Related Art An ice heat storage tank for taking in water from an ice heat storage tank and sending it to a subcooler and discharging the water cooled by the subcooler in the ice and water slurry state into the ice heat storage tank to store heat. Is known. In such an ice heat storage tank, in order to avoid problems such as freezing and blockage of water in the subcooler, water before being sent to the subcooler is preheated. The cold water deprived of heat by this preheating is stored in a cold water heat storage tank, and the cold heat is utilized for cooling the refrigerant on the secondary side.

FIG. 2 shows an outline of a conventional heat storage system having both an ice heat storage tank 50 and a cold water heat storage tank 51. In the figure,
The solid line arrow indicates the water flow direction during heat storage, and the dotted line arrow indicates the water flow direction during heat dissipation.

At the time of heat storage, the water in the ice heat storage tank 50 is pumped up by the pump 54 through the filter 53 at the bottom of the tank and sent to the subcooler 55, which is -2 to -3 ° C.
The supercooled water that has been cooled to a certain degree is discharged to the release pipe 56 installed in the upper portion of the ice heat storage tank 50. In the release pipe 56, the supercooled water becomes a slurry state of ice and water and is discharged into the ice heat storage tank 50. The slurry-like ice and water discharged into the ice heat storage tank 50 are separated into ice and water due to the density difference, and the water is pumped up again by the pump 54 and sent to the subcooler 55. In this way, when the temperature of the water in the ice heat storage tank 50 drops to around 2 ° C, ice formation starts,
After that, the temperature of the water in the ice heat storage tank 50 is maintained at 0 ° C.
The subcooler 55 is circulated and supplied with brine cooled to below freezing point by a refrigerator unit (not shown).

In order to preheat the water before sending it to the subcooler 55, the water pumped from the bottom of the ice heat storage tank 50 is pumped from the circuit 60 provided on the upstream side of the pump 54.
The water is taken by the operation of No. 1 and circulated and supplied to the primary side of the heat exchanger 62, while the water on the high temperature side in the cold water heat storage tank 51, that is, the upper part of the tank is taken from the circuit 63 by the pump 64 and the heat exchanger 6
It is circulated and supplied to the secondary side of 2, and heat exchange is performed between the two. The temperature of the water supplied to the primary side of the heat exchanger 61 is approximately 0 ° C. On the other hand, the water on the high temperature side in the cold water heat storage tank 51 supplied to the secondary side of the heat exchanger 61 is generally about 12 ° C. because it is used as a heat source for cooling or the like.

As a result of the heat exchange, the circuit 60 to the heat exchanger 62
The water in the ice heat storage tank 50 supplied to the temperature rises to about 10 ° C., then is returned from the circuit 65 and is again cooled by the supercooler 5.
Combine with water before sending to 5. By raising the temperature of the water before being sent to the subcooler 55 to about 0.5 ° C. in this way, problems such as freezing and blockage of water in the subcooler 55 are avoided.

On the other hand, the water in the cold water heat storage tank 51 supplied from the circuit 63 to the heat exchanger 62 becomes cold water of about 4 ° C. by heat exchange, and from the circuit 66 to the low temperature side in the cold water heat storage tank 51, that is, the lower part of the tank. Will be returned. As a result, cold water of about 4 ° C. is stored in the cold water heat storage tank 51.

During heat dissipation, the ice heat storage tank 50
Water pumped from the bottom by the pump 54 is sent to the primary side of the heat exchanger 70, and heat exchange is performed with the load-side refrigerant that is circulated and supplied to the secondary side of the heat exchanger 70. As a result of the heat exchange, the water sent from the ice heat storage tank 50 is heated up to about 12 ° C., and then returned from the return circuit 71 to the upper portion of the ice heat storage tank 50 again. Similarly, the water at the bottom of the cold water heat storage tank 51 is pumped up by the pump 72 and sent to the primary side of the heat exchanger 73 to exchange heat with the refrigerant on the load side circulated and supplied to the secondary side of the heat exchanger 73. Let The temperature of the water pumped from the bottom of the cold water heat storage tank 51 and supplied to the primary side of the heat exchanger 73 is approximately 4 ° C. However, as a result of heat exchange, the temperature of the water rises to approximately 12 ° C. The cold water heat storage tank 51 is returned from the return circuit 74.
Returned to the top of. Thus, the refrigerant on the load side was about 14 ° C. before being supplied to the secondary side of the heat exchanger 70 and the heat exchanger 73, while it was about 7 ° C. after the heat exchange, and became a load device. Returned to.

[0009]

As described above, in the prior art, the water exchanged between the water pumped from the bottom of the ice heat storage tank 50 and the water on the high temperature side in the cold water heat storage tank 51 is taken into consideration in consideration of pipe corrosion and the like.
Water is preheated before being sent to the subcooler 55 by performing heat exchange using. Therefore, a pump 54 for supplying the water of the ice heat storage tank 50 to the primary side of the heat exchanger 61 and a pump 64 for supplying the water of the cold water heat storage tank 51 to the secondary side of the heat exchanger 62 are always provided. There is a need. In addition, three heat exchangers, that is, a heat exchanger 62 for preheating, a refrigerant heat exchanger 70 for heat dissipation, and a heat exchanger 73 are required. As described above, in the conventional heat storage system, a space for installing a plurality of pumps and heat exchangers is required, and the equipment cost is high.

Further, in the conventional system, considering the approach of the heat exchanger, only cold water of about 4 ° C. can be stored in the cold water heat storage tank 51, and the temperature of the water after heat exchange is about 12 ° C.
The temperature in the cold water heat storage tank 51 is about 8 ° C.
It only stays in use due to the temperature difference. Therefore, when the volume of the cold water heat storage tank 51 is small, a sufficient amount of preheat cannot be secured. If the temperature of the cold water in the cold water heat storage tank 51 is 4 ° C
If it can be made even lower than this, the difference in utilization temperature becomes wider, and the amount of heat storage per volume of the cold water heat storage tank increases. that way,
The heat storage transfer rate of the daytime load can be increased, and the ratio depending on the heat source machine such as another refrigerator during the daytime can be reduced.

An object of the present invention is to reduce the number of pumps and heat exchangers installed in the heat storage system having both the ice heat storage tank and the cold water heat storage tank as described above, thereby reducing the installation space and reducing the equipment cost. The aim is to reduce the amount of heat and to increase the amount of heat stored in the cold water heat storage tank.

[0012]

According to the present invention, the water in the ice heat storage tank is taken and sent to the subcooler, and the water cooled by the subcooler is put in a slurry state of ice and water in the ice heat storage tank. A heat storage system comprising an ice heat storage tank for discharging heat to store heat and a cold water heat storage tank, wherein the water taken from the ice heat storage tank at the time of heat storage is mixed with water on the high temperature side in the cold water heat storage tank. And a circuit that supplies part or all of the water after taking in heat from the ice heat storage tank and radiating heat to the cold water heat storage tank, and the height of the water surface of the ice heat storage tank and the height of the water surface of the cold water heat storage tank. In order to make them equal, a heat storage system that has a circuit that supplies water in the ice heat storage tank to the low temperature side in the cold water heat storage tank at the time of heat storage and supplies water at the low temperature side in the cold water heat storage tank to the ice heat storage tank at the time of heat radiation Provided.

[0013]

In the heat storage system of the present invention, when preheating the water before being cooled by the subcooler during heat storage, the indirect method using the heat exchanger as in the prior art is not used, but the high temperature side of the cold water heat storage tank, That is, the water taken from the upper part of the cold water heat storage tank is directly mixed with the water taken from the ice heat storage tank to raise the temperature. In this case, for example, the amount of water taken from the upper part of the cold water heat storage tank is adjusted with respect to the water taken from the ice heat storage tank so that the temperature of the mixed water becomes about 0.5 ° C. . By supplying water preheated to about 0.5 ° C. after mixing in this way to the subcooler, problems such as freezing and blockage of water in the subcooler are eliminated.

When water is taken from the cold water heat storage tank and preheated in this way, the amount of water in the cold water heat storage tank corresponding to the amount of water taken decreases. Therefore, the water in the ice heat storage tank corresponding to the amount of water intake is supplied to the low temperature side in the cold water heat storage tank via the circuit connecting the ice heat storage tank and the cold water heat storage tank, and the water quantity in the cold water heat storage tank is insufficient. By compensating for this, the height of the water surface of the ice heat storage tank and the height of the water surface of the cold water heat storage tank are made equal. The water in the ice heat storage tank is kept at 0 ° C. after ice is generated in the ice heat storage tank, and as a result, cold water at 0 ° C. is sequentially supplied to the cold water heat storage tank from the bottom, and eventually, Cold water of 0 ° C is stored in the entire cold water heat storage tank. As described above, the heat storage system of the present invention can increase the heat storage amount of the cold water heat storage tank as compared with the conventional heat storage system.

On the other hand, when heat is dissipated in the heat storage system of the present invention, water is taken from the ice heat storage tank and the water is supplied to the primary side of the heat exchanger for cooling the refrigerant on the load side. And when returning the water which became about 12 degreeC by radiating heat with a heat exchanger to an ice heat storage tank, it is made to return a part or all of it to a cold water heat storage tank.

When a part or all of the water after heat dissipation is returned to the cold water heat storage tank in this way, the amount of water in the ice heat storage tank is correspondingly reduced. Therefore, the same amount of water as the water returned to the cold water heat storage tank is supplied from the low temperature side in the cold water heat storage tank to the ice heat storage tank via the circuit that connects the cold water heat storage tank and the ice heat storage tank, Make the water level of the tank equal to the water level of the ice storage tank. As a result, the cold water of 0 ° C stored in the cold water heat storage tank is stored in the ice heat storage tank during heat storage,
The cold heat is further used for cooling the refrigerant on the load side.

[0017]

Embodiments of the present invention will be described below. Figure 1
It is a flow figure showing the outline of the heat storage system concerning the example of the present invention. In the figure, the arrow drawn with a solid line indicates the flow direction of water during heat storage, and the arrow drawn with a dotted line indicates the flow direction of water during heat dissipation.

An ice heat storage tank 1 and a cold water heat storage tank 2 are provided adjacent to each other. The ice heat storage tank 1 and the cold water heat storage tank 2 are filled with water, and the water in both tanks is connected by a circuit 3. Water in the ice heat storage tank 1 and the cold water heat storage tank 2 freely flows through this circuit 3, and the water surface of the ice heat storage tank 1 and the water surface of the cold water heat storage tank 2 are always kept equal. In the cold water heat storage tank 2, the circuit 3 is open to the low temperature side (bottom of the tank).

One end of the circuit 4 is opened at the bottom of the ice heat storage tank 1, and a filter 5 is provided at the opening. A valve 6 and a pump 7 are provided in the middle of the circuit 4, and the valve 6 is a pump 7
On the suction side (between filter 5 and pump 7). The other end of the circuit 4 branches into a circuit 8 and a circuit 9, and the circuit 8 is connected to the valve 10
Is connected to the subcooler 11. The subcooler 11 is circulated and supplied with brine cooled below freezing (for example, about −6 ° C.) by a refrigerator (not shown). A release pipe 12 is provided below the discharge port of the supercooler 11.
On the other hand, the circuit 9 is connected to the primary inlet of the heat exchanger 13,
The primary outlet of the heat exchanger 13 communicates with the upper portion of the ice heat storage tank 1 via a circuit 14. The circuit 14 includes a valve 18
Is provided. The load side refrigerant is circulated and supplied to the secondary side of the heat exchanger 13 via the circuits 15 and 16 by the operation of the pump 17.

On the other hand, one end of the circuit 20 opens on the high temperature side (upper part of the tank) of the cold water heat storage tank 2, and the other end of the circuit 20 branches into a circuit 21 and a circuit 22. The circuit 21 is connected via a valve 23 between the valve 6 of the circuit 4 and the pump 7. The circuit 22 is connected via a valve 24 between the heat exchanger 13 of the circuit 14 and the valve 18.

Next, the operation of the heat storage system of the embodiment configured as described above will be described separately for the heat storage operation and the heat radiation operation.

[Heat storage operation] During heat storage operation, valve 1 of circuit 8
0 is opened, the valve 42 of the circuit 14 is closed, and the water pumped up from the bottom of the ice heat storage tank 1 via the circuit 4 by the pump 7 is supplied to the circuit 8
Sent to the subcooler 11. The brine cooled below freezing point (for example, about -6 ° C.) by a refrigerator (not shown) is circulated and supplied to the subcooler 11, and heat is exchanged with the brine in the subcooler 11 to be in a supercooled state. The water is discharged to the release pipe 12, and becomes a slurry state of ice and water, and is discharged to the upper portion in the ice heat storage tank 1. The slurry-like water discharged into the ice heat storage tank 1 is separated into ice and water due to the density difference, and the water is again pumped up from the circuit 4 by the pump 7 and sent to the subcooler 11 via the circuit 8. In this way, when the temperature of the water in the ice heat storage tank 1 drops to around 0 ° C., ice generation starts, and thereafter, the temperature of the water in the ice heat storage tank 1 is maintained at 0 ° C. The ice generated in the ice heat storage tank 1 has a property that snow is immersed in water. In this way, ice is generated and stored in the ice heat storage tank 1.

On the other hand, when preheating the water in the subcooler 11 in order to prevent it from freezing or blocking, the valve 23 of the circuit 21 is opened and the high temperature side of the cold water heat storage tank 2, that is, the upper portion of the cold water heat storage tank 2 The taken water is supplied to the suction side of the pump 7 of the circuit 4 and mixed with the water taken from the ice heat storage tank 1. The water taken from the high temperature side of the cold water heat storage tank 2 has a temperature of about 12 ° C. due to heat exchange with the refrigerant on the load side,
By mixing the water at about 12 ° C. with the water taken from the ice heat storage tank 1, the mixing amount is controlled so that the temperature of the mixed water becomes about 0.5 ° C. The control of the mixing amount is performed by adjusting the opening degree of the valve 6 provided on the upstream side of the pump 7 of the circuit 4 and the opening degree of the valve 23 of the circuit 21.
For example, if the opening degree of the valve 6 is decreased and the opening degree of the valve 23 is increased, the mixing amount of water taken from the high temperature side of the cold water heat storage tank 2 increases and the temperature of the water after mixing rises. On the contrary, if the opening degree of the valve 6 is increased and the opening degree of the valve 23 is decreased, the mixing amount of water taken from the high temperature side of the cold water heat storage tank 2 is reduced and the temperature of the water after mixing is lowered. By adjusting the temperature of the water after mixing and supplying the water preheated to about 0.5 ° C. to the subcooler 11, problems such as freezing and blockage of water in the subcooler 11 can be solved.

When water is taken from the cold water heat storage tank 2 during preheating as described above, the amount of water in the cold water heat storage tank 2 corresponding to the amount of water taken in decreases. Then, the water in the ice heat storage tank 1 is supplied to the low temperature side (bottom of the tank) in the cold water heat storage tank 2 via the circuit 3 connecting the ice water heat storage tank 1 and the cold water heat storage tank 2 to each other. The shortage of water in the interior is compensated. As a result, the height of the water surface of the ice heat storage tank 1 and the height of the water surface of the cold water heat storage tank 2 are kept equal.

The water thus supplied from the ice heat storage tank 1 to the cold water heat storage tank 2 is kept at approximately 0 ° C. after the ice is generated in the ice heat storage tank 1, and as a result, the cold water is stored. The cold water of 0 ° C. is sequentially supplied to the heat storage tank 2 from the lower part, and the cold water of 0 ° C. is sequentially stored from the lower part in the cold water heat storage tank 2. As described above, according to the heat storage system of the embodiment, the temperature of the cold water when the heat is stored in the cold water heat storage tank 2 can be lowered by about 4 ° C. as compared with the conventional case, and the heat storage amount can be increased. Become.

By performing the heat storage operation in this way, ice is generated and stored in the ice heat storage tank 1, and cold water of approximately 0 ° C. is stored and stored in the cold water heat storage tank 2.

[Heat dissipation operation] Next, when heat dissipation operation is performed in a state where ice is generated in the ice heat storage tank 1 and cold water of 0 ° C. is stored in the cold water heat storage tank 2 as described above, Valve 10 of 8
Is closed and the valve 18 of the circuit 9 is opened. And the ice heat storage tank 1
The water pumped from the bottom of the
Supply from the circuit 9 to the primary side of the heat exchanger 13,
The heat exchange with the refrigerant on the load side, which is circulated and supplied to the secondary side of 3, is performed. As a result of heat exchange, the refrigerant on the load side is cooled from about 14 ° C to about 7 ° C. On the other hand, the water sent from the ice heat storage tank 1 is heated up to about 12 ° C. and returned to the upper part of the ice heat storage tank 1 from the circuit 14. Thus ice storage tank 1
When water of about 12 ° C. is returned to the upper part of the ice, the ice generated in the ice storage tank 1 starts to melt due to the heat of the water, but as long as ice remains in the ice storage tank 1, the ice storage tank The temperature of the water in 1 is maintained at 0 ° C.

Further, the water after the temperature is raised in this way is stored in the ice heat storage tank 1
When returning to the upper part of, the part or all of it is taken out to the circuit 22 and returned to the high temperature side of the cold water heat storage tank 2 (upper tank). The amount of water drawn into the circuit 22 can be changed by adjusting the opening of the valve 18 of the circuit 14 and the opening of the valve 24 of the circuit 22. For example, the opening degree of the valve 18 is reduced and the valve 24 is
When the opening degree of is increased, the amount of water returning to the ice heat storage tank 1 is reduced and the amount of water returning to the cold water heat storage tank 2 is increased. Conversely, if the opening degree of the valve 18 is increased and the opening degree of the valve 24 is decreased, the amount of water returning to the ice heat storage tank 1 increases and the amount of water returning to the cold water heat storage tank 2 decreases.

When the water returned to the ice heat storage tank 1 is taken and supplied to the cold water heat storage tank 2 as described above, the amount of water in the ice heat storage tank 1 corresponding to the amount of water taken decreases. Then, the water on the low temperature side (bottom of the tank) in the cold water heat storage tank 2 is supplied to the ice heat storage tank 1 through the circuit 3 that connects the cold water heat storage tank 2 and the ice heat storage tank 1, and the shortage is compensated. I, the height of the water surface of the ice heat storage tank 1 and the cold water heat storage tank 2
The height of the water surface is kept the same. As I explained earlier,
Due to the heat storage operation, 0 ° C. cold water is stored in the cold water heat storage tank 2, and the 0 ° C. water is sequentially taken in from the lower part of the cold water heat storage tank 2, and the ice heat storage tank is passed through the circuit 3. 1
Since it is supplied inside, the temperature of the water in the ice heat storage tank 1 is still maintained at 0 ° C.

By thus releasing the cold heat stored in the ice heat storage tank 1 and the cold water heat storage tank 2 by the heat storage operation, the temperature of the water in the ice heat storage tank 1 and the cold water heat storage tank 2 is 12 ° C. at the maximum. The refrigerant on the load side, which is circulated and supplied to the secondary side of the heat exchanger 13, can be cooled until. Therefore,
According to the heat storage system of this embodiment, the water in the cold water heat storage tank 2 can be used with a temperature difference of about 12 ° C.

[0031]

In the conventional heat storage system, the temperature of the water in the cold water heat storage tank can be lowered to about 4 ° C. at the most, and the difference in use temperature is about 8 ° C. even if the maximum is taken. The heat storage system can reduce the temperature of the water in the cold water heat storage tank to almost 0 ° C., and a maximum temperature difference of about 12 ° C. can be taken. Therefore, according to the heat storage system of the present invention, the amount of heat stored in the cold water heat storage tank can be increased to about 1.5 times that of the conventional case. As a result, the peak cut rate of daytime load can be increased, the heat source unit capacity can be reduced, and the running cost can be significantly reduced. Further, since the heat storage system of the present invention has a small number of heat exchangers and pumps installed, the installation space can be reduced and the facility cost can be reduced.

[Brief description of drawings]

FIG. 1 is a flow chart showing an outline of a heat storage system according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an outline of a conventional heat storage system.

[Explanation of symbols]

 1 Ice heat storage tank 2 Cold water heat storage tank 11 Supercooler

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Bunkyo Hasegawa 6-4 Tokiwahirayanagicho, Matsudo City, Chiba Prefecture Minami Heights 303 (72) Inventor Masaharu Kamishiro 5-9-9 Burazo, Urawa City, Saitama Prefecture

Claims (1)

[Claims] 1. An ice heat storage tank for taking in water from an ice heat storage tank and sending it to a subcooler, discharging the water cooled by the subcooler in the ice and water slurry state into the ice heat storage tank to store heat. And a cold water heat storage tank, which is a circuit for mixing the water taken from the ice heat storage tank with the water on the high temperature side in the cold water heat storage tank during heat storage, and from the ice heat storage tank during heat dissipation. In order to make the height of the water surface of the ice heat storage tank equal to the height of the water surface of the cold water heat storage tank, a circuit that returns part or all of the water after taking in and radiating heat to the cold water heat storage tank A heat storage system that has a circuit that supplies water to the low temperature side in the cold water heat storage tank and supplies the low temperature side water in the cold water heat storage tank to the ice heat storage tank during heat dissipation.