JPH0510509Y2 - - Google Patents

Description

[Detailed explanation of the idea]

Industrial Application Field This invention relates to a device for cooling underground power cables using a heat pipe, and can be used in industries related to power transmission and distribution. Conventional technology For example, at the outlet of a substation, multiple lines of power cables are laid, and as the power cables are concentrated, the temperature rises near the outlet.Especially in the summer, the outside temperature is high. Cooling by outside air may become insufficient, and as a result, power transmission capacity may have to be reduced. Conventionally, the temperature rise has been suppressed by circulating cooling water or oil between the power cable or its vicinity and a cooling heat exchanger, or by increasing the size of the power cable. However, such conventional means have problems such as increased initial cost due to large-scale equipment and construction, and increased running cost when using a cooler. Conventionally, in order to solve such problems, a method has been considered in which the power cable is cooled by transporting the heat generated by the power cable to a cooling part such as the atmosphere using a heat pipe. When using a heat pipe, if the area to be cooled is about 200 meters or less, it can be cooled without any problems and has the advantage of requiring almost no maintenance. If the heat pipe is thin, the heat pipe cannot be placed along the power cable, and in such a case, it is necessary to reduce the heat transfer resistance between the power cable and the heat pipe as much as possible. In addition, when cooling is performed using outside air, it is necessary to take some means to temporarily support the power cable since the outside temperature becomes quite high, especially during the daytime in summer. Purpose of the invention This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a cooling device that can constantly cool underground power cables well. Structure and operation of the device This device is capable of inserting a power cable into any one of a plurality of conduits formed to pass the power cable therethrough, and also inserting the power cable into any of the other conduits through which the power cable is not inserted. A heat pipe whose one end is connected to the cooling section is inserted, and inside the pipe into which the heat pipe is inserted, a non-magnetic metal wool and a latent heat storage material that stores heat as latent heat due to a change in state are inserted. Further, the open end of the conduit filled with the metal wool and the latent heat storage material is sealed with a cap, and one of the caps is structured to be expandable and contractable.
Therefore, in this invention, metal wool mediates heat transfer to the heat pipe, and metal wool has good thermal conductivity, and since it is a non-magnetic material, there is no heat generation due to electromagnetic induction. The heat generated by the power cable can be efficiently transferred to the heat pipe, and when outside air is used as the cooling source,
At low temperatures such as at night, the latent heat storage material solidifies and stores so-called cold heat, so when the outside temperature is high during the day, the power cable is cooled by the so-called cold heat stored by the latent heat storage material. be able to. Furthermore, since one of the caps that seals the pipes has a structure that expands and contracts, increases and decreases in the volume of the latent heat storage material due to temperature changes and state changes can be absorbed by the expansion and contraction of the cap. It is possible to fill the pipe without creating any voids and improve the heat transfer coefficient. Embodiments Hereinafter, embodiments of this invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic exploded perspective view showing one embodiment of this invention, in which a concrete block 2 forming a plurality of conduits 1 for power cable insertion is buried underground, and both ends of the concrete block 2 are buried underground. A vertical hole or hand hole 3 is formed on the side. A power cable 4 is inserted through any plurality of the pipes 1 among the pipes 1, and the power cable 4 is pulled out from the hand hole 3 to the ground and connected to ground equipment 5. Further, a heat pipe 6 is inserted from one end of the empty pipe line 1 through which the power cable 4 is not inserted, and the end of the heat pipe 6 is
It is connected to a cooler 7 installed on the ground via a hand hole 3. As the cooler 7, either a structure in which air is cooled by forcibly blowing the atmospheric air onto the end of the heat pipe 6, or a structure in which the end of the heat pipe 6 is air-cooled by natural ventilation can be used. Further, both ends of the pipe line 1 into which the heat pipe 6 is inserted are sealed by caps 8 and 9 as shown in FIG. As shown in Figure 3, they are sealed to such an extent that no voids are formed.
Here, one of the caps 8 and 9 is a bellows cap that is expandable and retractable so as to allow thermal expansion of the contents in the conduit 1 into which the heat pipe 6 is inserted. In addition, the metal wool 10
This is for promoting heat exchange between the inner wall of the conduit 1 and the heat pipe 6, and is made by intertwining fine wires of non-magnetic metal such as copper.
Further, when the temperature of the outside air is low, the latent heat storage material 11 solidifies by being removed from heat through the heat pipe 6, and as a result, the so-called cold heat changes state (phase change).
This is something that is stored as latent heat that accompanies it, and polyethylene glycol can be used as an example. Next, to explain the operation of the device configured as above, the heat generated from the power cable 4 during power transmission warms the concrete block 2, but when the temperature exceeds the temperature of the outside air, the concrete block 2 and Since there is a temperature difference between the concrete block 2 and the heat pipe 6, heat transfer occurs from the concrete block 2 to the heat pipe 6. In that case, the metal wool 10 is sealed together with the latent heat storage material 11 inside the pipe line 1 into which the heat pipe 6 is inserted.
mediates heat transfer from the inner wall of the conduit 1 to the heat pipe 6, and since the metal wool 10 has a high thermal conductivity, heat can be efficiently transferred to the heat pipe 6. And the heat pipe 6 is
The applied heat evaporates the internal working fluid, and the vapor flows to the end on the cooler 7 side and liquefies heat, thereby transporting heat as latent heat.
In other words, the heat generated from the power cable 4 is given to the outside air.
can be cooled by outside air. Further, when the temperature of the outside air is considerably low, such as at night in winter, the latent heat storage material 11 is cooled to a temperature close to that of the outside air, and as a result, the latent heat is also taken away and solidified.
In other words, so-called cold heat is stored as latent heat. In that case, since the metal wool 10 is mixed with the latent heat storage material 11, the metal wool 10 becomes a nucleus and the latent heat storage material 11 solidifies, thereby preventing the supercooling phenomenon in which the latent heat storage material 11 does not solidify even below the freezing point. can do. After the latent heat storage material 11 stores cold heat as described above, when the temperature of the outside air increases during the daytime, the amount of heat absorbed through the heat pipe 6 decreases, but the latent heat storage material 11 absorbs the heat of fusion. For,
The power cable 4 can be cooled by the latent heat storage material 11 until the latent heat storage material 11 completely melts and the temperature rises to the temperature of the outside air. The heat storage material 11 expands and contracts when heated and cooled. In the above embodiment, the pipe line 1 is sealed, but the cap 8 is a bellows cap, and the latent heat storage material 11 expands and contracts. Since it is configured to expand and contract as the pipe line 1 changes, it is possible to prevent inconveniences such as changes in the internal pressure of the pipe line 1 and leakage of the latent heat storage material 11 due to the change in the internal pressure. Figure 1 shows the results of a specific example of this invention together with the results of a comparative example without a heat pipe.As is clear from this table, by cooling with a heat pipe, the allowable current and It is recognized that the power transmission capacity will increase.

【table】

[Table] Effects of the invention As is clear from the above explanation, according to this invention, since the metal wool with high thermal conductivity mediates heat transfer to the heat pipe, heat absorption through the heat pipe, that is, the power cable Cooling can be performed efficiently, and at the same time, since the metal wool serves as the nucleus for solidification of the latent heat storage material, overcooling of the latent heat storage material can be prevented. Furthermore, since the metal wool is non-magnetic, it is possible to prevent electromagnetic induction phenomena and associated heat generation during power transmission. Furthermore, in this design, the latent heat storage material sealed in the conduit in which the heat pipe is inserted stores so-called cold heat as latent heat when it solidifies, so the solidified latent heat storage material acts to supplement the cooling of the power cable. Therefore, even if the temperature change in the cooling section is large, the power cable can be cooled without any particular problem. Furthermore, in this invention, since one of the caps that seals the conduit containing the latent heat storage material has an expandable structure, changes in the volume of the latent heat storage material can be absorbed by the expansion and contraction of the cap, and as a result, Since the latent heat storage material can be filled into the pipe to such an extent that no voids are formed, the heat transfer coefficient is improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an embodiment of this invention, FIG. 2 is a schematic diagram showing a sealed structure of a conduit, and FIG. 3 is a sectional view of a conduit into which a heat pipe is inserted. 1... Conduit, 4... Power cable, 6... Heat pipe, 7... Cooler, 10... Metal wool, 11... Latent heat storage material.

Claims (1)

[Scope of utility model registration request] Insert the power cable into one of the plurality of conduits formed to insert the power cable, and connect one end to the cooling unit to any other conduit through which the power cable is not inserted. Insert a heat pipe into which the heat pipe is inserted, and fill the pipe line into which the heat pipe is inserted with non-magnetic metal wool and polyethylene glycol that stores heat as latent heat accompanying state changes. A cooling device for an underground power cable using a heat pipe, characterized in that the open end of a conduit filled with wool and polyethylene glycol is sealed with a cap, and one of the caps is structured to expand and contract.