JPH0449024B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to air conditioning and refrigeration equipment, and more particularly, to an improvement of the equipment in which a latent heat storage device is added to cover the cooling and refrigeration loads. Conventionally, various techniques for adding a heat storage device to a heat utilization device have been proposed. This uses cheap late-night electricity to store heat and dissipate it when needed according to the demands of the load, thereby adjusting the time lag between heat supply and demand and contributing to energy savings. . Naturally, many such ideas have been proposed in the field of air conditioning and refrigeration. For example, this can be seen in Utility Model Publication No. 46-443. That is, a technology has been proposed in which a cold heat storage tank is added to the brine circulation system between the evaporator and the cooler, and a large number of cold heat storage bodies each containing a cold medium stored in a shell are housed in this cold heat storage tank. has been done. Looking at the shell that accommodates the cooling medium in this prior art, that is, looking at the cooling medium, the cooling medium is densely packed within the shell. Therefore, since the space inside the shell accommodates as much of the cooling medium as possible, it has the advantage of increasing heat storage capacity, but it is difficult to prevent the volumetric expansion of the cooling medium when it changes from liquid phase to solid phase. No improvements have been made. Therefore, there are several problems to be solved in practical use, such as damage to the shell due to repeated use and consideration of the material of the shell, without consideration of durability. Therefore, regarding this cooling medium, a technique is being considered in which, when filling the shell with the cooling medium, a relatively large space is created in advance in the shell so that 100% of the volumetric expansion of the cooling medium can be absorbed. For example, it can be seen in JP-A-53-55547. According to this conventional technology,
When the cooling medium expands in volume, the space absorbs the amount of expansion, so there is no damage to the shell due to this volumetric expansion. However, in order to leave enough space from the beginning to absorb the entire amount of volumetric expansion, the capacity of the cooling medium is reduced by the amount necessary, and the heat storage capacity is reduced. This is a point that cannot be ignored since the number of cold/heat media accommodated in the cold heat storage tank is large. The present invention has been made in view of the above points, and its gist is that it is provided with an evaporator, a compressor, a condenser, and an expansion valve, and that a brine circulation system is used between the evaporator and the cooler. A cold heat storage tank is attached to this brine circulation system, and a large number of heat storage bodies each containing a cold heat medium in a spherical shell are housed in the cold heat storage tank, and the cold heat medium is transferred from a liquid phase to a cold heat storage tank. It has the property of storing cold heat as the latent heat of solidification when changing from a solid phase to a liquid phase, and dissipating the previously stored cold heat when changing from a solid phase to a liquid phase, and when changing from a liquid phase to a solid phase, its volume increases. In a cooling or freezing device that has the property of expanding and is set so that a space remains in the spherical shell when the cooling medium is in a liquid phase, the space in the spherical shell that remains when the cooling medium is in a liquid phase is The volume is
The size is not determined to absorb all of the volumetric expansion of the cooling and heating medium when the cooling and heating medium changes from a liquid phase to a solid phase, but is determined to absorb only a part of the volumetric expansion. , the spherical shell is made of a material that expands concentrically in response to the volumetric expansion of the cooling medium so that the remaining volumetric expansion of the total volumetric expansion can be absorbed by the concentric expansion of the spherical shell. A cooling and freezing device characterized in that the range of the concentric bulge of the spherical shell is set within the elastic limit of the material of the spherical shell, and its purpose is to: When the volumetric expansion of the cooling and heating medium occurs, the volumetric expansion of the cooling and heating medium can be absorbed by the small amount of space left inside the shell and the concentric expansion of the shell. At the same time, the durability of the shell is improved, and at the same time, as much cooling medium for latent heat storage as possible can be accommodated within the shell, and a large amount of cold heat storage capacity is secured in the limited size cold heat storage tank. be. Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In FIG. 1, refrigerant vapor generated in an evaporator 1 is compressed by a compressor 2 to become high-pressure superheated vapor, and in a condenser 3, heat is removed by cooling water and becomes a liquid. This high-pressure liquid is depressurized by an expansion valve 4, the low-pressure low-temperature refrigerant is evaporated by an evaporator 1, the heat of evaporation is removed from the brine with a low freezing point, and the brine is cooled. and sent to a cooler 6 for cooling and freezing. A heat storage tank 7 stores cold heat in the brine circulation system 5 and radiates the heat.
Attached. In this example, an evaporator 1 is placed inside, its upstream and downstream sides are connected by a pipe 8, and a heat storage tank 7 is arranged in the middle of the pipe 8. And the pipe 8
A bypass pipe 9 is provided in parallel with the above. Three-way control valves 10 and 1 are provided at the connection points between the pipe 8 and the brine circulation system 5 and the connection points between the pipe 9 and the brine circulation system 5, respectively.
1, 12, and 13, and an evaporator circulation pump 14 and a cooling pump 15 are also arranged in the brine circulation system 5. Inside the heat storage tank 7, a large number of spherical heat storage bodies 16 as shown in FIG. 2 are accommodated. This spherical heat storage body 16 stores cold heat as the latent heat of solidification when changing from a liquid phase to a solid phase at the solidification temperature, and uses a spherical cooling medium 17 to release the previously stored cold heat when changing from a solid phase to a liquid phase. It is filled in the shell 18. The individual size of the spherical heat storage bodies 16 is 20 mm in diameter.
mm to 200 mm, for example about 65 mm, but this is because the required storage and heat radiation amount of the entire heat storage tank is determined by the conditions of the cooling and refrigeration equipment, heat storage and radiation operation conditions, etc. , it may be determined based on ensuring a sufficient heat transfer area to ensure the amount of heat dissipation. Preferably, at the same time, the above conditions are satisfied, since the larger the number of spherical heat storage elements 16 accommodated in a certain volume of the heat storage tank 7, that is, the smaller the diameter of each spherical heat storage element 16, the higher the manufacturing cost. , it is preferable to process it so as to satisfy this manufacturing condition. Furthermore, when accommodating this spherical heat storage body 16 in the heat storage tank 7, there are other steps not shown, such as,
It is preferable that plates with a large number of communication holes are installed near one inlet or outlet and the other inlet or outlet of the heat storage tank 7, and the spherical heat storage body 16 is housed between the plates. By doing this, when the brine goes in and out of the heat storage tank 7, the brine is dispersed by the plates, goes in and out of the heat storage tank 7, and is averaged over the spherical heat storage bodies 16 that are accommodated in large numbers. be brought into contact with. Furthermore, the moving speed of the brine in the heat storage tank 7 is extremely slow, and the speed is set to ensure a moving amount of brine of 5 m ³ per hour, for example, depending on the conditions of the equipment. stipulate. Now, regarding the cooling medium 17, a eutectic mixture is used in this example. That is, an aqueous solution of a heat medium such as a salt can obtain the lowest solidification temperature at a certain concentration, and a solution having a concentration that provides the lowest temperature is used. According to the eutectic mixture with this eutectic concentration, the heat medium such as salts and water solidify as if they were a single substance at the lowest temperature. Therefore, it operates reliably and stably in the melting-solidification cycle. At this time, as the latent heat of solidification, the cooling medium 17
stores heat. Some examples of such eutectic mixtures are shown below.

[Table] The above eutectic concentrations are weight concentrations. According to the cooling medium of the eutectic mixture in this example, the heat of solidification and fusion during solidification and melting is 50 to 72 Kcal/Kg.
It is something that occurs. Of course, a nucleating agent such as calcium carbonate to prevent supercooling, an agent for preventing separation of crystal water such as sodium polyacrylate, and a crystal accelerator such as silver iodide are added to the cooling medium 17. In other words, in order to prevent supercooling, if a nucleating agent is not used, the freezing point will often fall significantly (10 to 20°C) below the original freezing point. By using this, the temperature can be suppressed to around 2°C at maximum and the operation becomes stable. Regarding agents for preventing separation of crystal water, the melting point of many hydrated salts is the peritectic point, but in this case uniform melting does not occur at the melting point. That is, the crystal separates into two phases: a crystal with a composition different from that of the original crystal (low water of crystallization) and a melt with a composition in equilibrium with this crystal. For this purpose, it is effective to add a small amount of clay as a gelling agent. In particular, in this invention, the cooling medium 17 is
The size of the shell 18 is determined so that a space 19 not occupied by the cooling medium 17 is formed within the shell 18 when it is in the liquid phase. However, the size of the space 19 is designed not only to simply form a space, but also to absorb the volumetric expansion due to solidification of the cooling medium through both the space 19 and the concentric expansion of the shell 18. It is determined. When the cooling medium changes from a solid phase to a liquid phase, the shell 18 also contracts, but the shell 18 stops contracting, leaving a space 19 of the initially set size.
For example, if the cooling medium 17 becomes solid and expands by 1.08 times its volume when it is a liquid, that is, by 8%, then the space 19
The size of the space 19 is determined so as to absorb the expansion amount of 5.5% by the expansion of the shell 18 and 2.5% by the expansion of the shell 18. In other words, the cooling/heating medium 17 is formed by hollow molding,
When filling the spherical shell 18 processed by vacuum forming method etc. by injection etc., it is natural that the cooling medium 1
7 is a liquid, but when filling the liquid cooling/heating medium 17, the space 19 is 5.5% in the above example.
Fill it with a considerable amount remaining. The spherical shell 18 itself is a hard ball, but because it is formed with a thin wall, it expands according to the expansion of the cooling medium due to the internal pressure when the solidified cooling medium expands, and when the cooling medium changes to a liquid phase. It naturally returns to its original state while leaving the original space, for example, a softening point of 90
Among the synthetic resins having a temperature of ℃ or higher, high-density polypropylene and high-density polyethylene are preferable in consideration of other stress resistance, heat resistance, and processability. As described above, the spherical shell 18 expands and contracts, and the range of concentric expansion of the spherical shell is set within the elastic limit of the material of the spherical shell. This allows the spherical shell 18 to always maintain its spherical shape by withstanding repeated expansion and contraction. Next, each operation of this embodiment will be explained with reference to FIGS. 4 to 8. The operation example shown in FIG. 4 is only a heat storage operation. In this case, the brine cooled by removing the heat of evaporation by the evaporator 1 is circulated only between the evaporator and the cold heat storage tank 7 by the pump 14 as shown by the arrow 20. As a result, the brine comes into contact with a large number of spherical heat storage bodies 16 in the heat storage tank 7, whereby the spherical heat storage bodies 16 are cooled and solidified at the eutectic point. During solidification, cold heat as latent heat of solidification is stored in the cold heat medium 17 of the spherical heat storage body 16. The operation example shown in FIG. 5 is a case where the compressor 2 is driven to perform cooling and freezing operations while storing heat. That is, as shown by the arrow 21, the brine is circulated through the cooler 6 by the pump 15 while cooling.
This is an example in which heat is stored by circulating it also to the cold heat storage tank 7 by the pump 14 according to the refrigeration load. In this example, the brine leaving the cooler 6 is transferred to the bypass pipe 9
The water is returned to the cooler 6 via the. Therefore, the temperature of the brine is adjusted according to the degree of the return amount, and the cooling and freezing combinations are adjusted. The operation example shown in FIG. 6 is an example in which cooling and freezing operations are performed only by the heat dissipation operation of the heat storage tank. That is, as shown by the arrow 22, the operation of the compressor 2 of the cooling and refrigeration cycle system is stopped, and the brine is circulated between the cold heat storage tank 7 and the cooler 6 by the pump 15. When the brine that has passed through the cooler 6 flows into the cold heat storage tank 7, the heat is transferred to the cold heat storage tank 7.
When it reaches the eutectic point, the cold heat medium 17 melts and releases the previously stored cold heat to the brine as latent heat of melting. Therefore, the brine is cooled to meet the cooling and refrigeration load. In this example, a portion of the brine leaving the cooler 6 is returned to the cooler 6 via the bypass pipe 9 to adjust the temperature of the brine. The example shown in FIGS. 7 and 8 is an example in which cooling and freezing operations are performed by both the heat dissipation operation of the heat storage tank and the driving operation of the compressor 2, as shown by arrows 23 and 24. However, in the example shown in FIG. 7, a portion of the brine leaving the cooler 6 is returned to the cooler 6 via the bypass pipe 9. Three-way control valves 10, 11, 1 are used to enable the above-mentioned various cooling, freezing, heat storage, and heat radiation operations.
2 and 13 and pumps 14 and 15 are switched and started/stopped depending on the case by a conventionally known control method. Normally, the storage of cold heat in the cold heat storage tank 7 is carried out by driving the compressor late at night when the charges are low, and the heat is radiated when the load demand is high. For this reason, as illustrated in Fig. 3, A is shown in the request pattern for cooling and refrigeration loads, and for example, when a heat storage device is not provided, at around 14 to 15 hours at the maximum load, Assuming that the compressor capacity is about 100KW, having a heat storage device will allow you to drive the compressor during other times when cheap late-night electricity is available and store heat.
However, since the heat can be radiated during the time period when cooling and freezing are required, the capacity of the compressor can be reduced to, for example, 50KW, contributing to energy conservation. Now, in the process of heat storage and heat dissipation, since the cold medium 17 in the spherical heat storage body 16 used in the present invention is a eutectic mixture with a eutectic concentration, it is possible to significantly lower the freezing point, and the lowered solidification , which effectively stores and radiates latent heat during phase change at the melting temperature. Furthermore, the above-mentioned melting-solidification operation is performed as if it were a single substance, so the operation is stable and practical. Therefore, when enclosing the liquid-phase cooling medium 17 in the shell 18, not only is the space 19 defined and sealed in the shell 18, but also the cooling medium 17 is sealed.
When the volume of the cooling medium 17 expands due to the change from the liquid phase to the solid phase, the amount of expansion is absorbed by the space 19 and the concentric expansion of the shell 18 corresponding to the volumetric expansion of the cooling medium 17. In addition to being able to respond to the volumetric expansion of the medium during solidification, it is also possible to fill as much of the cooling medium as possible, so the amount of heat stored in each spherical heat storage element can be increased, and the heat storage capacity of the entire heat storage tank can be increased. It is possible to increase the capacity. Furthermore, since the spherical latent heat storage bodies 16 are used, even if they are packed closely together, the contact between the spherical latent heat storage bodies 16 is point contact, so there is no large resistance to the flow of hot water, and desired flow and passage can be ensured. Therefore, since it can be densely packed, the amount of heat exchange can be increased. In addition, the number of hot water dispersion plates for holding these spherical latent heat storage bodies in the heat storage tank and enabling the distributed inflow of hot water is required and is easy to process. Furthermore, it is easy to fill the heat storage tank with the spherical heat storage bodies because they are simply placed in the heat storage tank without being lined up, and the spherical heat storage bodies are automatically arranged in a regular manner. As detailed above, according to the present invention, when the cooling medium for storing latent heat changes from a liquid phase to a solid phase, it expands in volume, but this volumetric expansion is absorbed by the space initially left in the shell. At the same time, it is absorbed not only by the space but also by the concentric bulges of the shell, so it is sufficiently suitable for practical implementation. Moreover, the range of the concentric bulge of the spherical shell is set within the limits of the material of the spherical shell. Therefore, there is no damage to the shell,
Highly durable. In particular, the size of the space is not set to a size that allows the space itself to absorb the volumetric expansion of the cooling medium, i.e., part of the volumetric expansion is absorbed by the concentric bulges of the shell. It can only accommodate more cooling medium for latent heat storage. Therefore, the heat storage capacity of each latent heat storage body becomes large, and the heat storage capacity within the limited space of the heat storage tank can be increased. In addition, since the shell is bulged concentrically, no local stress is applied to the shell, and in this sense, it has various practical advantages such as being highly durable.

[Brief explanation of the drawing]

The attached drawings show embodiments of the present invention, in which Fig. 1 is a piping system diagram, Fig. 2 is an example of a spherical heat storage body, Fig. 3 is an example of a heat storage operation pattern, and Figs. 4 to 8 are each This is an operation example diagram, in which 1 is an evaporator, 2 is a compressor,
3 is a condenser, 4 is an expansion valve, 5 is a brine circulation system,
6 is a cooler, 7 is a cold heat storage tank, 16 is a spherical heat storage body, 17 is a cold medium, 18 is a spherical shell, and 19 is a space.

Claims (1)

[Claims] 1 Equipped with an evaporator 1, a compressor 2, a condenser 3, and an expansion valve 4, the evaporator 1 and the cooler 6 are connected by a brine circulation system 5, and a cold heat storage tank 7 is connected to the brine circulation system 5. A large number of heat storage bodies 16 each having a cold heat medium 17 housed in a spherical shell 18 are housed in the cold heat storage tank 7, and the cold heat medium 17 solidifies when changing from a liquid phase to a solid phase. It has the property of storing cold heat as latent heat and dissipating the previously stored cold heat when changing from the solid phase to the liquid phase, and also has the property of expanding its volume when changing from the liquid phase to the solid phase. In a cooling or freezing device that is set so that a space remains in the spherical shell 18 when the cooling medium 17 is in the liquid phase, the volume of the space in the spherical shell 18 that remains when the cooling medium 17 is in the liquid phase is:
The size is not determined to absorb all of the volumetric expansion of the cooling and heating medium when the cooling and heating medium changes from a liquid phase to a solid phase, but is determined to absorb only a part of the volumetric expansion. , the remaining amount of volumetric expansion out of the total amount of volumetric expansion is determined by the amount of volumetric expansion of the spherical shell 18.
The spherical shell 18 is made of a material that expands concentrically in accordance with the volumetric expansion of the cooling medium, and the range of the concentric expansion of the spherical shell 18 is , a cooling and freezing device characterized by being set within the elastic limit of the material of the spherical shell 18.