JP2000356368A - Heat storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart bending process to a circulating pipe for passing refrigerant therethrough with a smaller bending radius and more improve density of the pipe by forming the circulating pipe by providing resin layers to the inside and outside of a thin metallic pipe. SOLUTION: A circulating pipe 11 for passing refrigerant therethrough is formed by providing resin layers 15, 16 to the outside and inside of a thin metal pipe 14, respectively. Bending process is imparted to the circulating pipe 11 by means of a wood pattern or a metal mold so as to have a meandering shape with series of bent portions therein. Metallic material having some modulus of elasticity and excellent property for bending process, is preferably used for the thin metal pipe 14. For the resin layers 15, 16, a material having excellent anticorrosiveness, chemical resistance, flexibility and moldability, and of low cost is preferably used. The thickness of the thin metal pipe 14 and the resin layers 15, 16 is suitably determined in consideration of the anticorrosiveness, bending process property, heat exchanging efficiency and the like.

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 used for air conditioning equipment in a building or the like, and more particularly to a heat storage system using latent heat of a heat storage material such as ice.

[0002]

2. Description of the Related Art As a heat storage system used for an air conditioner of a building or the like, there is an ice heat storage system utilizing the latent heat of ice. In this ice heat storage system, a circulation pipe through which a refrigerant flows is arranged in a heat storage tank in which water is stored, and by circulating the refrigerant through the circulation pipe, water around the circulation pipe is frozen, Ice is attached to the circulation tube to store heat. This heat storage is performed using inexpensive nighttime power, for example. Then, if necessary, the cold water is circulated to the air conditioner to radiate heat.

Conventionally, a circulating pipe provided in a heat storage tank has been used by winding a cross-linked polyethylene pipe, a copper pipe or the like in a coil shape. However, the circulation pipe wound in a coil shape has a problem that the amount of ice adhering to the circulation pipe is limited due to the low density of the circulation pipe in the heat storage tank, and the heat storage amount is small. Was.

For this reason, in the heat storage system disclosed in, for example, Japanese Utility Model Publication No. 6-20036, in order to increase the density of the circulation pipe in the heat storage tank, a plurality of circulation pipes are formed in parallel with each bent portion. Bend continuously so as to be located in a zigzag shape within the plane to be arranged, and arrange the adjacent circulation pipes in a staggered manner, and make the refrigerant flow directions of the adjacent circulation pipes reverse. I have. According to this, it is possible to arrange the circulation pipes in the heat storage tank at a high density, and there is little possibility that ice adhering to the adjacent circulation pipes will coalesce, and the water in the heat storage tank will be evenly distributed. Temperature distribution. As a circulation pipe used in such a heat storage system,
An extruded polyethylene pipe or copper pipe which is bent in a zigzag shape is generally used.

[0005]

In recent years, further improvement in heat storage efficiency has been demanded, and with this, it is necessary to reduce the bending radius of the bent portion of the circulation pipe to increase the density of the circulation pipe. Has become. However, when a polyethylene pipe is bent into a hairpin shape, the minimum bending radius is restricted by the compressive strength of the material, so that a smaller bending radius cannot be obtained, and there is a limit in improving the pipe density.

In the case of heat storage using ice formed by freezing pure water, since the solidification temperature is 0 ° C., the brine flowing through the circulation pipe has a low temperature of about −10 ° C. to −7 ° C. When using a relatively high temperature brine, an inorganic salt such as calcium chloride, sodium acetate or sodium sulfate having a higher freezing point than water may be used as the heat storage material. Further, for example, Japanese Patent Laid-Open No. 6-80
No. 960 also discloses a technique in which silver iodide obtained by adding an iodide solution to a silver nitrate solution and precipitating the same is used as a water supercooling inhibitor. When using these chemically synthesized heat storage materials, since the brine may be at a relatively high temperature,
Although the output of the brine cooler can be small, there is a problem that the chemically synthesized heat storage material corrodes piping such as copper. In order to prevent corrosion, it is conceivable to enclose a synthetic heat storage material in a resin capsule to indirectly store heat, but this has a problem of poor thermal efficiency.

[0007] When a heat storage system is newly installed in an existing building or the like, an existing water tank may be used as a heat storage tank and a circulating pipe may be installed in the water tank in order to reduce the introduction cost. . In this case, the conventional heat storage system
Although cross-linked polyethylene pipes and copper pipes are used as circulation pipes, the space for carrying circulation pipes into existing water tanks is often narrow, and it is difficult to carry in circulation pipes that are bent in a zigzag shape. It is necessary to remove the wall or carry in the state of small parts and process it in the water tank, which is problematic in terms of work efficiency and cost.

Accordingly, a first object of the present invention is to make it possible to bend a circulating pipe with a smaller bending radius to further improve the pipe density.

Further, the present invention provides a circulating pipe which is easy to bend and has a shape-retaining property, so that it does not corrode even when a chemically synthesized heat storage material is used as a heat storage material.
A second object is to make it possible to store heat with relatively high-temperature brine.

Further, the present invention aims at facilitating the loading of the circulation pipe from a narrow space by maintaining the shape at the time of processing in advance and simultaneously folding the processed circulation pipe compactly. This is the purpose of 3.

[0011]

Means for Solving the Problems In order to solve the above problems, the present invention has taken the following technical means. That is, the present invention is a heat storage system for storing heat by freezing a heat storage material in a heat storage tank with a refrigerant flowing through a circulation pipe provided in the heat storage tank, wherein the circulation pipe has a thin metal wall. It is characterized in that a resin layer is provided inside and outside the tube.

In the heat storage system of the present invention, since the circulation pipe is provided with the resin layer inside and outside the metal thin-film pipe, the compression strength of the circulation pipe can be increased, and therefore, the circulation pipe in which buckling occurs is generated. Can be reduced, and the tube density in the heat storage tank can be increased to improve ice making efficiency. Therefore, even when the circulating tube has a bent portion and the bending radius of the bent portion is four times or less the outer diameter of the circulating tube, it is possible to perform bending without buckling, thereby further improving the pipe. The density can be improved. The thickness of the thin metal tube is determined in consideration of the pressure resistance, but from the viewpoint of bending workability, it is preferably about 1% of the outer diameter of the circulation tube.

Further, since a resin layer having corrosion resistance is formed on the inner and outer layers of the circulation pipe, the heat storage material in the heat storage tank is
Even when a chemically synthesized heat storage material is used, corrosion of the circulation pipe is prevented, heat storage efficiency can be improved, and the metal layer is provided in the middle, so that shape retention and bending workability are improved. More specifically, as the heat storage material, a chemically synthesized heat storage material having a freezing point higher than the freezing point of water and lower than room temperature can be used. In this case, if the thickness of the circulating tube is less than 1 mm, the pressure resistance and the shape retention are too small, and if it exceeds 3 mm, the heat exchange efficiency is deteriorated.
m is preferable. As the chemically synthesized heat storage material, a material having a latent heat of fusion as large as possible is preferable. For example, a material containing an inorganic salt such as calcium chloride hexahydrate, sodium acetate, and sodium sulfate as a main component can be used.

Further, since the circulation pipe has a structure in which a thin metal layer is provided on the intermediate layer of the resin pipe, it is possible to maintain the shape at the time of processing in advance, and to compactly fold the processed circulation pipe as a whole. Thus, the circulation pipe can be easily carried into the heat storage tank from a narrow space, and a new heat storage system using an existing water tank can be easily installed at low cost. For example, the circulation pipe is bent into a coil shape or a zigzag shape, and the metal thin tube is bent so that the entire bent circulation tube can be compactly reduced and deformed within the elastic deformation range of the metal thin tube. The thickness may be set. In order to increase the pipe density, a circulation pipe bent in a zigzag shape is preferably used.

Preferably, the thin metal tube is made of aluminum. The reason is that in the case of copper,
This is because an oxidative deterioration reaction may occur, and in the case of steel, the bending elasticity is high and bending workability is poor.

The resin layer is preferably made of polyethylene. The reasons are corrosion resistance, chemical resistance,
Excellent moldability from the viewpoint of flexibility, viscosity and thermal stability,
And because it is low cost. Further, in the case of an aluminum metal thin-walled tube, it is preferable to use a crosslinked polyethylene showing good adhesiveness.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. The basic configuration of the heat storage system according to the present embodiment is the same as that disclosed in Japanese Utility Model Publication No. 6-20036. To be described below, the heat storage system freezes part of the heat storage material that is liquid at room temperature in the heat storage tank 10 to store heat as shown in FIGS. 2 and 3, and stores the heat in the heat storage tank 10 as necessary. By sending the heat storage material to the air conditioner 20 by the pump 30, the room is air-conditioned. Thermal storage tank 1
A plurality of circulation pipes 11 through which the refrigerant flows are disposed in 0. For example, chlorofluorocarbon flows as a refrigerant in the circulation pipe 11, and the fluorocarbon expands and evaporates to remove heat from the surroundings, and the heat storage material freezes around the circulation pipe 11. The Freon flowing through each circulation pipe 11 is condensed in a condenser 50 after being compressed by a compressor 40, and is expanded in an expansion valve 6.
The heat is circulated through the circulation pipes 11 in the heat storage tank 10 through the heat storage tank 10. Various refrigerants can be used as the refrigerant flowing through the circulation pipe 11. For example, brine such as antifreeze is used, and a cooler (evaporator or the like) for brine is provided instead of the condenser. The low temperature liquid obtained by heat exchange of the brine with the cooler can be circulated in the circulation pipe.

Each circulating tube 11 is continuously bent in a hairpin shape such that each bent portion is located in a plane (for example, a horizontal plane) in a zigzag manner. Adjacent circulation pipes 11
Are supported by a suitable support member (not shown) so as to be staggered at predetermined intervals in the vertical direction. Each end of each circulation pipe 11 is provided with a feed header 12 for distributing the refrigerant supplied from the expansion valve 60 into each circulation pipe 11, and a compressor 40 which collectively transmits the refrigerant flowing through each circulation pipe 11. It is connected to a discharge header 13 for feeding to the discharge head. In this case, one end of each circulation pipe 11 is connected to the feed header 12 so that the flow direction of the refrigerant flowing in each adjacent circulation pipe 11 is opposite, and the other end is connected to the other end. The end is connected to the discharge header 13.

In the illustrated embodiment, each header 12, 1
Numerals 3 are arranged side by side on one side of the circulation pipe 11, and the coolant flows through one circulation pipe 11 from the side where the headers 12 and 13 are disposed, and the circulation pipe 11 is continuously bent. Part 1
1a, the straight pipe part 1 along the juxtaposed bent part
It is returned to the discharge header 13 via 1b. The circulation pipe 1 adjacent to the circulation pipe 11 through which the refrigerant flows as described above
1, a straight pipe portion 11c along the bent portion arranged side by side,
The refrigerant is once passed to the side opposite to the side where the headers 12 and 13 are provided, flows from the side into the continuously bent portion 11d of the circulation pipe 11, and then returns to the discharge header 13. Is done.

In the heat storage system having the above configuration, the condenser 50
The refrigerant condensed in the above flows through the circulation pipes 11 through the supply headers 12 and expands and evaporates in the circulation pipes 11. Thereby, the heat storage material around each circulation pipe 11 is frozen and adheres to the outer peripheral surface of each circulation pipe 11. Since the refrigerant is heated while flowing through the circulation pipe 11 and its cooling capacity is reduced, the amount of ice adhering to the outer peripheral surface of the circulation pipe 11 increases on the connection side of the supply header 12. Then, as the cooling capacity decreases due to the flow of the refrigerant, the amount of ice adhering to the circulation pipe 11 decreases sequentially.

At this time, each of the circulation pipes 1 adjacent in the vertical direction
1 are arranged in a staggered manner, and since the refrigerant flow direction of each circulation pipe 11 is opposite, the refrigerant flow direction of one circulation pipe 11 is opposite. The portion of the one circulation pipe 11 connected to the supply header 12 is located near the portion of the other circulation pipe 11 connected to the discharge header 13, and as a result, the portion of the one circulation pipe 11 to which a large amount of ice has adhered. In the vicinity, there is a portion of the other circulation pipe 11 where the amount of adhered ice is small. Therefore, there is little possibility that the ice adhered to each circulation pipe 11 will coalesce. As described above, the ice frozen in each circulation pipe 11 is melted when the heat load of the air conditioner 20 is increased, and the cold water in the heat storage tank 10 is supplied to the air conditioner 20.

The feature of the heat storage system of the present embodiment lies in the structure of the circulation pipe 11. That is, as shown in FIG. 1, the circulation pipe 11 includes resin layers 15 and 16 inside and outside the thin metal pipe 14.
Is provided. Such a circulation pipe 11
Can be manufactured by, for example, laminating resin layers 15 and 16 inside and outside of a straight metal thin-walled tube 14 by an extrusion molding method. The above-described configuration is obtained by bending the circulating tube 11 into a zigzag shape having a bent portion continuously using a wooden mold or a mold as described above.

As the thin metal tube 14, it is preferable to use a metal material having an appropriate bending elastic modulus and excellent bending workability. For example, an aluminum tube can be used.
The resin layers 15 and 16 have corrosion resistance, chemical resistance,
An inexpensive material that is excellent in flexibility and moldability is preferable. For example, crosslinked polyethylene can be used.
The thickness of the thin metal tube 14 and the resin layers 15 and 16 is
It is appropriately set in consideration of pressure resistance, bending workability, heat exchange efficiency, and the like. For example, the thickness of the thin metal tube 14 is
From the viewpoint of bending workability, about 1% of the outer diameter is preferable.
The thickness of the thin metal tube 14 is preferably set to such an extent that the entire circulating tube 11 can be compactly reduced and deformed within the range of elastic deformation of the thin metal tube 14. Therefore,
Although it is not preferable to make the thickness of the thin metal tube 14 and the resin layers 15 and 16 much larger than the diameter of the circulation tube 11, the thickness of each of the resin layers 15 and 16 is 0 mm of the diameter of the circulation tube 11. 0.006 times or more, and the thickness of the metal tube 14 is preferably 0.006 times or more the diameter of the circulation tube 11.

According to the heat storage system according to the above embodiment, the pipe density in the heat storage tank 10 can be increased, the ice making rate can be improved, and the circulation pipe 11 is not corroded by rust, and the circulation pipe 11 is bent. Can be easily performed and appropriate shape retention can be provided. Further, even if a chemically synthesized heat storage material is used as the heat storage material, the circulation pipe 11 is not corroded, the chemically synthesized heat storage material can be used positively, and heat can be stored by relatively high-temperature brine.

Furthermore, since the entire circulation pipe 11 can be folded, the circulation pipe 11 can be easily carried into a narrow place. The present invention can be applied to a circulating tube 11 bent into a coil as shown in FIG. 4, and can be applied to a circulating tube 11 bent into a zigzag as shown in FIG. However, a zigzag shape is preferable for improving the tube density.

[0026]

EXAMPLES Hereinafter, results of various performance evaluations of the heat storage systems according to Examples of the present invention and Comparative Examples by various tests will be described.

[Ice making rate performance test by the structure of the circulation pipe] Example of the present invention Comparative example 1 Comparative example 2 --------------------------------------------------------------------------- −−−−−− Circulating tube structure Overall shape Zigzag Zigzag Zigzag Outer diameter 16mm 16mm 16mm Wall thickness 1.5mm 1.5mm 1.5mm Aluminum wall thickness 0.2mm − − Inner / outer resin layer Crosslinked polyethylene − − Material − Crosslinked polyethylene copper −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Bending radius 50mm 80mm 50mm Bending workability good good × corrosion resistance good good × ice making rate 90 % 70% 90%----------------------------

Here, the bending radius of the circulation pipe of Comparative Example 1 was set to 8
The reason why the length is set to 0 mm is that if the bending radius is smaller than this, buckling occurs. That is, the following results were obtained by the bending limit test of the circulation pipe of the example and the circulation pipe of Comparative Example 1. Here, x indicates that the tube buckled. Bending radius 5D 4D 3D 2D (Diameter D = 16mm) -------------------------------------------------------- (Example) Aluminum composite tube ○ ○ ○ × (Comparative Example 1) Polyethylene tube ○ × × × −−−−−−−−−−−−−−−−−−−−−−−−−−−−−

As is clear from the ice making rate performance test, according to the examples of the present invention, good results were obtained in all of the bending workability, corrosion resistance, and ice making rate.

[Performance Test According to Type of Heat Storage Material Used] Example Comparative Example 3 Comparative Example 4 Comparative Example 5 --------------------------------------------------------------------------- −−−−−−−−−−− Circulating tube structure Outer diameter 16mm 16mm 16mm 16mm Wall thickness 1.5mm 1.5mm 1.5mm 1.5mm Aluminum wall thickness 0.2mm − 0.2mm − Inner and outer resin layers Crosslinked polyethylene − Crosslinked polyethylene − Material − Copper-Copper Heat storage material Calcium chloride Calcium chloride Ice Ice Brine temperature 5 ° C 5 ° C -7 ° C -7 ° C Ice making rate 90% 92% 90% 92% ----------- Comparative Example 4 uses an aluminum composite pipe as a circulation pipe, and therefore, is not included in the present invention. However, it is listed here as a comparative example in the sense of comparison with the one using a chemically synthesized heat storage material as the heat storage material. .

As described above, those using calcium chloride as the heat storage material (Example and Comparative Example 3) have the same ice making as the case using ice, although the brine temperature is relatively high (about 5 ° C.). Rate can be secured. However, according to Comparative Example 3, as shown in the following corrosion resistance evaluation,
Corrosion of the copper circulation tube clearly progressed and could not be used for a long time. However, according to the embodiment of the present invention, since the outer layer is covered with polyethylene, good corrosion resistance is exhibited.

Corrosion resistance evaluation test (evaluation of retention of tensile elongation) (Evaluated after immersion test in 50% calcium chloride solution) Immersion time 100 hours 1000 hours 2000 hours------------------ −−−−−−−−−−−−−−− Cross-linked polyethylene 98% 97% 97% Copper 97% 70% 30%

[Reduction test of circulating pipe] Outer diameter of circulating pipe 16
mm, the pipe thickness is 1.5 mm, and an aluminum pipe having a thickness of 0.2 mm is used as a thin metal pipe.
With respect to the circulating tube of the present invention having a 5 mm polyethylene layer, those which were bent into a coil shape and a zigzag shape were manufactured, and a folding test was performed.

FIG. 4 shows the case of a coiled circulation pipe,
FIG. 4A shows the overall shape and dimensions during processing in a state of being disposed in the heat storage tank, and FIG. 4B shows a folded state. As shown in the figure, according to the embodiment of the present invention, the circulating pipe having a total height of 800 mm at the time of installation can be reduced and deformed to a total height of 70 mm. At the time of installation,
When the state was returned to the state shown in FIG. 4A, the coil shape shown in FIG.

FIG. 5 shows the case of a zigzag circulation pipe, FIG. 5 (a) shows the overall shape of the heat storage tank when it is processed, and FIG. 4 (b) shows the folded state. Is shown. As is clear from the figure, it can be understood that the entire width of the circulation pipe can be considerably reduced, and that the circulation pipe can be easily carried in from a small space. Even in this case, at the time of installation, FIG.
When the state was returned to the state shown in FIG. 5A, the zigzag shape shown in FIG. From this, it can be seen that even if the folding is performed, the aluminum layer is not plastically deformed because the twisting is only slight.

According to the present invention, the circulation pipe can be bent with a smaller bending radius, and the heat storage efficiency can be further improved by further improving the pipe density. In addition, even though it is a circulating tube that is easy to bend and has shape retention properties, it can be made not to corrode even when a chemically synthesized heat storage material is used as a heat storage material. Heat can be stored. In addition, it is possible to maintain the shape of the circulation pipe in advance at the time of processing, and at the same time, to be able to compactly fold the processed circulation pipe as a whole, thereby facilitating the loading of the circulation pipe from a narrow space. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of a circulation tube according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an overall configuration of a heat storage system according to the embodiment.

FIG. 3 is a perspective view showing an arrangement structure of a circulation pipe in a heat storage tank of the heat storage system.

4A and 4B show an embodiment of a coiled circulation pipe, wherein FIG. 4A is a perspective view of an arrangement state at the time of bending processing, and FIG.

5A and 5B show an embodiment of a zigzag circulation pipe, wherein FIG. 5A is a perspective view of an arrangement state at the time of bending processing, and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Thermal storage tank 11 Circulation tube 14 Thin metal tube 15 Outer resin layer 16 Inner resin layer

Claims (6)

[Claims] 1. A heat storage system for storing heat by freezing a heat storage material in a heat storage tank with a refrigerant flowing through a circulation pipe provided in the heat storage tank, wherein the circulation pipe is a thin metal pipe. A heat storage system characterized in that a resin layer is provided inside and outside the device. 2. The heat storage system according to claim 1, wherein the thin metal tube is made of aluminum. 3. The heat storage system according to claim 1, wherein the resin layer is made of polyethylene. 4. The heat storage system according to claim 1, wherein the circulation pipe has a bent portion, and a bending radius of the bent portion is four times or less the outer diameter of the circulation tube. . 5. The heat storage material is a chemically synthesized heat storage material having a freezing point higher than the freezing point of water and lower than room temperature, and the thickness of the circulation pipe is 1 to 3 mm.
The heat storage system according to any one of claims 4 to 4. 6. The circulating pipe is bent in a coil shape or a zigzag shape, and within a range of elastic deformation of the thin metal tube,
The heat storage system according to any one of claims 1 to 5, wherein the thickness of the thin metal tube is set so that the entire bent circulating tube can be compactly reduced and deformed.