JPS6122437Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an indirect cooling structure for underground power cables.

As is well known, power cables generate heat and rise in temperature as power is transmitted, so their power transmission capacity is limited to a range that does not cause damage to the insulation coating, etc. Therefore, conventional methods have been used to increase the allowable power transmission capacity. Therefore, the cables are cooled. Direct cooling methods and indirect cooling methods are known as cable cooling methods, but direct buried power cables have two methods:
An indirect cooling method is used in which a cooling medium such as water is passed through cooling pipes buried near the cable, and the heat generated in the cable is transferred to the cooling medium for cooling. If a directly buried power cable is cooled using the above method, the temperature rise due to heat generation in the cable can be suppressed to some extent, and the allowable power transmission capacity can be improved. Since heat is transferred through the soil, it is not always possible to obtain a sufficient amount of heat transfer due to the large heat transfer resistance of the soil.In other words, the cooling effect of the cable is low. Although it has the advantage of simple equipment, it has not been possible to significantly increase the allowable power transmission capacity.

This idea was made in view of the above circumstances,
The purpose of this invention is to provide an indirect cooling structure for underground power cables that has excellent cooling effects and can significantly increase power transmission capacity.

An embodiment of this invention will be described below with reference to the drawings. Fig. 1 shows an embodiment of this invention, and reference numeral 1 indicates a power cable buried underground. A cooling pipe 2 is buried in parallel as a cooling section, and a cooling medium 3 such as water flows in this cooling pipe 2. Furthermore, between the cable 1 and the cooling pipe 2, one end is connected to the cable 1. A heat pipe 4 is buried so that the other end thereof is located near the cooling pipe 2. This heat pipe 4 has a heat transport capacity that matches the expected calorific value of the cable 1 and the withstand temperature of the cable 1, and has a hollow tube 5 fitted in the middle part of the outer peripheral surface as shown in FIG. When the heat pipe 4 is attached, the inside of the hollow tube 5 is evacuated and a heat insulating layer 6 is formed therein, and fins 7 are provided at both ends of the heat pipe 4 to increase the heat transfer area.
a and 7b are attached.

In the cooling structure configured as shown in FIG. 1, the heat generated in the cable 1 during power transmission is transferred to one end of the heat pipe 4 and then transferred to the other end as latent heat of the working fluid in the heat pipe 4. and then transferred to the cooling medium 3 in the cooling pipe 2. In this case, since one end of the heat pipe 4 is located close to the cable 1, even if there is soil between them, there will be no problem in heat transfer from the cable 1 to the heat pipe 4. Without,
Similarly, no problem occurs in heat transfer between the heat pipe 4 and the cooling pipe 2. In addition, as mentioned above, since the heat insulating layer 6 is formed in the middle part of the heat pipe 4, the heat absorbed at one end of the cable 1 is transported far away from the cooling pipe 2 while being transported to the other end. Heat can be reliably transported to a location close to the cooling pipe 2 without being released into the soil at a location where the cooling pipe 2 is located. Therefore, according to the cooling structure shown in FIG. 1, the amount of heat transferred from the cable 1 to the cooling pipe 2 can be significantly increased compared to the conventional indirect cooling method. In other words, the cable 1 can be extremely effectively As a result, power transmission capacity can be increased to an unprecedented level.

Figure 3 shows another embodiment of this invention.
In this cooling structure, the cooling section is exposed to the atmosphere.
That is, a heat pipe 4 configured as shown in FIG. It was buried so that it slightly protrudes above the ground surface GL.

In the cooling structure configured as shown in FIG. 3, the heat generated in the cable 1 is radiated to the atmosphere via the heat pipe 4, and as a result, the cable 1 is cooled. In addition, even in this case, cable 1
Although soil is present between the heat pipe 4 and one end of the heat pipe 4, it does not impede heat transfer between the two for the same reason as explained in the embodiment shown in FIG. In addition, in the case of the cooling structure configured as shown in Fig. 3, since the hollow tubes 5 constituting the heat insulating layer 6 extend to the ground surface GGL, the ground surface GL is heated by sunlight and the temperature decreases. Even if it rises, the heat from the ground surface GL is not transferred to the heat pipe 4,
Therefore, the flow of the working fluid inside the heat pipe 4 is not hindered and the working fluid flows between the end on the cable 1 side and the end in the atmosphere, so the heat generated in the cable 1 is transferred to the atmosphere. The cable 1 can be effectively discharged and cooled.

Note that the heat insulating layer formed at the middle part of the outer circumferential surface of the heat pipe in this invention is not limited to the vacuum heat insulating layer as in the above embodiment, but may be formed by wrapping an appropriate heat insulating material around the outer circumferential surface of the heat pipe. It may be something that has been done.

As explained above, according to the indirect cooling structure of this invention, a heat pipe with a heat insulating layer formed in the middle part of the outer peripheral surface is arranged between the underground power cable and the cooling part, and the heat generated by the cable is transferred to the heat pipe. Since the heat is transported to the cooling section via the pipe, the heat generated in the cable can be transported to the cooling section without being dissipated into the soil at the middle part of the heat pipe.
Therefore, it is not only possible to obtain a much better cooling effect than the conventional indirect cooling method, but also compared to simply placing a heat pipe without a heat insulating layer between the underground cable and the cooling section. However, even greater cooling effects can be obtained. Therefore, according to the indirect cooling structure of this invention, the power transmission capacity of the underground power cable can be increased more than ever before.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of this invention, FIG. 2 is a sectional view showing a heat pipe thereof, and FIG. 3 is a schematic diagram showing another embodiment of this invention. 1... Underground power cable, 2... Cooling pipe, 4...
...Heat pipe, 6...Insulation layer.

Claims (1)

[Scope of utility model registration request] A heat pipe with a heat insulating layer formed in the middle of the outer circumferential surface is installed near the power cable buried underground.
An indirect cooling structure for an underground power cable, characterized in that it is disposed between the vicinity of the outer peripheral surface of the power cable and a cooling section located radially outward of the power cable.