CN112629305B - Heat dissipation device, system and method for underground closed pipeline - Google Patents

Abstract

The invention discloses a heat dissipation device, a system and a method for an underground closed pipeline, wherein the technical scheme is as follows: the vacuum tube sealing device comprises a sealing tube and a vacuum tube, wherein the middle part of the sealing tube is communicated with the vacuum tube through a first pipeline, and two sides of the sealing tube are respectively communicated with the vacuum tube through second pipelines; a plurality of tube bundles which are distributed at intervals are arranged in the sealing tube; the low-pressure air in the vacuum tube can form convective circulation airflow after heat exchange is completed in the sealing tube. According to the invention, the gas with lower density and higher heat in the vacuum tube is floated into the sealed tube/heat exchanger for heat exchange under the unpowered condition by the principles of severe pressure fluctuation and expansion with heat and contraction with cold generated by train operation; meanwhile, hot gas is filled in the heat exchanger to carry out convection and heat exchange with external air by utilizing the pressure difference generated by the head and the tail of the vehicle, so that the air convection effect is effectively enhanced, and the heat dissipation effect is improved.

Description

Heat dissipation device, system and method for underground closed pipeline

Technical Field

The invention relates to the technical field of pipeline heat dissipation, in particular to a heat dissipation device, a system and a method for an underground closed pipeline.

Background

The vacuum pipeline magnetic suspension train is made by using vacuum pipeline and superconducting magnetic suspension technology, and can overtake the pipeline traffic of jet passenger plane at speed per hour. The train runs in a closed vacuum pipeline, is not influenced by air resistance, friction and weather, and has high speed. At present, a testing machine and a complete experimental model are presented in the technology.

Due to the particularity of the vacuum environment, under the condition of 0.1atm, internal heat dissipation is blocked, heat is accumulated, the internal temperature of the pipeline can be obviously increased and even can reach more than 60 ℃ (when the blockage ratio is 0.23), the future actual operation and the internal personnel safety are influenced, the superconductor work is also influenced, and the cost of compartment refrigeration is increased.

In order to solve the problem of heat accumulation (mainly on the surface of a train), the problem needs to be solved by means of manual equipment with a heat exchange or refrigeration effect. The heat transfer to the outside is mainly carried out by the heat conduction of the tube wall, but the heat exchange by the tube wall is not enough to solve the problem. The common measures of tunnel (pipeline) cooling and heat dissipation mostly utilize capillary tubes or ventilation equipment, but the airtightness inside the pipeline can be influenced under the low vacuum environment, and the operation of a train is not facilitated.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a heat dissipation device, a system and a method for an underground closed pipeline.A sealing pipe/heat exchanger is additionally arranged at the upper part of a vacuum pipe, low-density hot gas in the pipeline flows upwards under the unpowered condition by utilizing natural convection and severe pressure fluctuation generated by train operation, and cold air flows back into the vacuum pipe after exchanging heat with a pipe bundle, so that part of gas with overhigh temperature and low density can naturally exchange heat without additional energy; meanwhile, the heat exchanger is additionally arranged outside the vacuum tube, and hot gas is filled in the heat exchanger to exchange heat with external air through the pressure difference between the head and the tail of the train generated by the running of the train, so that the air convection effect is effectively enhanced, and the heat dissipation effect is improved.

In order to achieve the purpose, the invention is realized by the following technical scheme:

in a first aspect, an embodiment of the present invention provides a heat dissipation apparatus for an underground sealed pipeline, including a sealing pipe and a vacuum pipe, where the middle of the sealing pipe is communicated with the vacuum pipe through a first pipeline, and two sides of the sealing pipe are respectively communicated with the vacuum pipe through second pipelines; a plurality of tube bundles which are distributed at intervals are arranged in the sealing tube; the low-pressure air in the vacuum tube can form convective circulation airflow after heat exchange is completed in the sealing tube.

As a further implementation manner, a plurality of tube bundles are respectively arranged in the space between the first pipeline and the two second pipelines in the sealing pipe.

As a further implementation mode, the distance between the first pipeline and the second pipeline is between 0 and D, wherein D is the outer diameter of the vacuum tube.

As a further implementation, the central angle between the connection point of the second conduit and the vacuum tube and the connection point of the first conduit and the vacuum tube may be an acute angle, a right angle or an obtuse angle.

As a further implementation manner, when the central angle is an acute angle, a right angle or an obtuse angle, the tube bundle can be horizontally arranged or installed at a set angle.

In a second aspect, an embodiment of the present invention further provides a heat dissipation apparatus for an underground closed pipeline, including a first heat exchanger, a vacuum tube, a first pipeline, and a second pipeline, where the first pipeline is connected to the middle of the vacuum tube, and the two sides of the first pipeline are symmetrically provided with the second pipeline communicated with the vacuum tube; the first pipeline and the second pipeline are connected with the first heat exchanger respectively to form a loop; the low-pressure air in the vacuum pipe can form convective circulating airflow after heat exchange is completed in the first heat exchanger.

As a further implementation manner, the first heat exchanger is respectively communicated with the first pipeline and the second pipeline through connecting pipes.

As a further implementation manner, the distance between the first pipeline and the second pipeline is between 0 and D, wherein D is the outer diameter of the vacuum tube; the central angle between the connection point of the first conduit and the vacuum tube and the connection point of the second conduit and the vacuum tube may be an acute angle, a right angle or an obtuse angle.

In a third aspect, an embodiment of the present invention further provides a heat dissipation system for an underground closed pipeline, including the heat dissipation device, where the vacuum pipe is connected to a plurality of second heat exchangers at intervals along an axial direction of the vacuum pipe.

In a fourth aspect, the embodiment of the invention also provides a heat dissipation method for the underground closed pipeline, by adopting the heat dissipation system, pressure difference is generated between the head and the tail of the train in the running process of the train, hot gas enters the second heat exchanger from the vacuum pipe for heat exchange, and the gas after heat exchange enters the vacuum pipe; due to thermal expansion and cooling of gas and severe pressure fluctuation generated by train operation, hot gas flows into the first heat exchanger for heat exchange along the first pipeline in the vacuum pipe, and cold gas after heat exchange enters the vacuum pipe along the second pipeline;

or because of the violent pressure fluctuation generated by the train operation, the hot gas fills the vacuum tube and the sealing tube, and according to the principle of expansion with heat and contraction with cold, the hot gas flows into the sealing tube along the first pipeline in the vacuum tube, flows into the second pipeline along the tube bundle direction after meeting the cooling of the tube bundle in the sealing tube, and finally enters the vacuum tube;

or the hot gas rises to the top of the sealing pipe, flows along the inner wall of the sealing pipe for heat exchange, flows into the second pipeline and finally flows into the vacuum pipe;

or the hot gas flows downwards along the direction of the first pipeline after contacting the top of the sealing pipe, then flows into the second pipeline along the pipe bundle after being contacted with the rising hot gas and is flushed to the pipe bundle by the hot air, and finally enters the vacuum pipe;

or the hot gas flows downwards along the direction of the first pipeline after contacting the top of the sealing pipe, then is flushed to the top of the sealing pipe by hot air after contacting the rising hot gas, flows along the inner wall of the sealing pipe for heat exchange, flows into the second pipeline, and finally flows into the vacuum pipe.

The beneficial effects of the above-mentioned embodiment of the present invention are as follows:

(1) according to one or more embodiments of the invention, a sealing pipe is arranged above the pipe wall of the vacuum pipe, so that gas with more heat and lower density can naturally float into the sealing pipe to complete heat exchange under the condition of no power, and then the gas completing heat exchange naturally sinks along with other pipelines due to heat reduction, thereby completing one-time heat exchanger type circulation simulating convection;

(2) according to one or more embodiments of the invention, the heat exchanger is arranged above the tube wall of the vacuum tube, so that gas with more heat and lower density can naturally float into the heat exchanger to complete heat exchange under the condition of no power, and then the gas completing heat exchange enters the vacuum tube along with another pipeline due to heat reduction, thereby completing one-time heat exchanger type circulation simulating convection;

(3) one or more embodiments of the invention utilize natural convection and severe pressure fluctuation generated by train operation to make hot air in the pipeline rise under unpowered condition by adding a heat exchanger outside the vacuum pipe and adding a sealing pipe/heat exchanger on the vacuum pipe in a matching way, and after cooling, cold air flows back into the pipeline, so that part of gas with overhigh temperature and low density can naturally exchange heat without additional energy; the differential pressure through locomotive rear of a vehicle production is with the inside and the outside air of hot gas flooding in the outer heat exchanger of vacuum tube convection current and heat exchange, has effectively strengthened the air convection effect, has increased heat transfer area, has promoted the radiating effect.

(4) According to one or more embodiments of the invention, a central angle between a connection point of a first pipeline and a vacuum pipe in a sealing pipe and a connection point of a second pipeline and the vacuum pipe is an acute angle, a right angle or an obtuse angle, and mainly aims at different working conditions, the central angle (distance between the first pipeline and the second pipeline in the sealing pipe) is determined according to the amount of hot gas generated, and the smaller the amount of hot gas generated in the vacuum pipe is, the smaller the corresponding value of the central angle is, so that waste of mounting materials is avoided, and unnecessary cost is reduced.

(5) In one or more embodiments of the invention, the included angle between the first pipeline in the sealing pipe and the pipe bundle is an acute angle or a right angle, and if the included angle between the first pipeline and the pipe bundle is a right angle, the manufacturing is simple and the installation is easy; if the included angle between the first pipeline and the tube bundle is an acute angle, the smaller the angle is, the more favorable the gas flows into the vacuum tube, and the backflow is prevented.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic diagram of a tube bundle horizontally arranged with a tube bundle having an acute central angle and a right angle to a first tube according to one or more embodiments of the present invention;

FIG. 2 is a schematic diagram of a tube bundle angled in an acute angle with respect to a central axis and a first tube bundle angled in accordance with one or more embodiments of the present invention;

FIG. 3 is a schematic illustration of a configuration of the present invention according to one or more embodiments with a right angle central angle and a right angle tube bundle angled with respect to the first tube, the tube bundle being horizontally disposed;

FIG. 4 is a schematic diagram of a tube bundle angled at an acute angle to the first conduit and having a central angle of a right angle according to one or more embodiments of the present invention;

FIG. 5 is a schematic view of a horizontal arrangement of a tube bundle having an obtuse central angle and a right angle tube bundle to a first tube according to one or more embodiments of the present invention;

FIG. 6 is a schematic diagram of a tube bundle angled arrangement according to one or more embodiments of the present invention with the central angle obtuse and the tube bundle angled acute with respect to the first conduit;

FIG. 7 is a schematic diagram of a heat exchange configuration using a heat exchanger according to one or more embodiments of the present invention with an acute central angle;

FIG. 8 is a schematic diagram of a heat exchange configuration utilizing a heat exchanger according to one or more embodiments of the present invention with a right angle center of curvature;

FIG. 9 is a schematic diagram of a heat exchange configuration using a heat exchanger according to one or more embodiments of the present invention with a central angle that is obtuse;

FIG. 10 is a schematic illustration of a heat dissipation system according to one or more embodiments of the present invention;

the system comprises a sealing pipe 1, a pipe bundle 2, a first pipeline 3, a second pipeline 4, a vacuum pipe 5, a train 6, a connecting pipe 7, a first heat exchanger 8 and a second heat exchanger 9.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;

for convenience of description, the words "up", "down", "left" and "right" in this application, if any, merely indicate correspondence with the directions of up, down, left and right of the drawings themselves, and do not limit the structure, but merely facilitate the description of the invention and simplify the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The terms "mounted", "connected", "fixed", and the like in the present application should be understood broadly, and for example, the terms "mounted", "connected", and "fixed" may be fixedly connected, detachably connected, or integrated; the two components can be connected directly or indirectly through an intermediate medium, or the two components can be connected internally or in an interaction relationship, and the terms can be understood by those skilled in the art according to specific situations.

The first embodiment is as follows:

the embodiment provides a heat abstractor for secret airtight pipeline, including sealed tube 1, vacuum tube 5 and the pipeline of connecting sealed tube 1, vacuum tube 5, in this embodiment, the middle part of sealed tube 1 is through first pipeline 3 and vacuum tube 5 intercommunication, and the both sides of sealed tube 1 are respectively through second pipeline 4 and vacuum tube 5 intercommunication.

Further, a plurality of tube bundles 2 distributed at intervals are installed inside the sealed tube 1, in this embodiment, a group of tube bundles 2 are respectively arranged in the space between the first pipeline 3 and the two second pipelines 4 inside the sealed tube 1, and each group of tube bundles 2 is provided with a plurality of tube bundles; the two ends of the tube bundle 2 are respectively fixed with the inner wall of the sealing tube 1.

The distance between the first pipeline 3 and the second pipeline 4 in the sealing tube 1 is 0-D (D is the outer diameter of the vacuum tube); the central angle β between the connection point of the second conduit 4 and the vacuum tube 5 and the connection point of the first conduit 3 and the vacuum tube 5 may be an acute angle, a right angle or an obtuse angle.

Further, as shown in fig. 1, the central angle β is an acute angle, and the tube bundle 2 may be arranged in a horizontal direction (perpendicular to the axial direction of the first pipe 3), that is, the angle α between the tube bundle 2 and the first pipe 3 is 90 °. The tube bundles 2 may also be arranged at a set angle, as shown in fig. 2, the ends of the two tube bundles 2 facing away from each other are inclined downwards, and the included angle α is an acute angle (0< α <90 °).

As shown in fig. 3, when the distance between the first pipe 3 and the second pipe 4 is D/2, the included angle α between the tube bundle 2 and the first pipe 3 is 90 °, and the central angle β is a right angle, i.e. the second pipe 4 is tangent to the vacuum tube 5. As shown in fig. 4, the central angle β is a right angle, and the angle α between the tube bundle 2 and the first tube 3 is an acute angle. As shown in fig. 5, the central angle β is an obtuse angle, and the tube bundle 2 is arranged in a horizontal direction, i.e. the included angle α is 90 °. As shown in fig. 6, the central angle β is an obtuse angle and the included angle α is an acute angle.

In the embodiment, the sealing pipe 1 is arranged above the pipe wall of the vacuum pipe 5 for heat exchange, so that the sealing performance in the pipeline is ensured as far as possible, the internal redundant heat is quickly counteracted and led out as far as possible, and the influence of the heat accumulation problem on the vehicle body and the interior of the vehicle body is reduced as far as possible.

The principle is as follows: by utilizing the physical phenomenon of expansion with heat and contraction with cold, the sealing tube 1 is arranged above the tube wall of the vacuum tube 5, so that gas with more heat and lower density can naturally float into the sealing tube 1 under the condition without power to complete heat exchange, and the gas for completing heat exchange can naturally sink along with the second pipeline 4, thereby completing the heat exchanger type circulation simulating convection once.

The gas is compressed at a place with high pressure by utilizing the severe periodic fluctuation of the pressure, negative pressure is formed along with the advancing of the train 6, the pressure difference generated at the same section is larger, the hot gas can enter the sealing pipe 1 from the vacuum pipe 5, and thus, the heat exchanger type circulation simulating convection is completed once.

Example two:

the embodiment provides a heat dissipation device for an underground closed pipeline, which comprises a first heat exchanger 8, a vacuum pipe 5 and a pipeline for connecting the first heat exchanger 8 and the vacuum pipe 5; in the embodiment, the middle position of the vacuum tube 5 is communicated with the first pipeline 3, and the two sides of the first pipeline 3 are symmetrically provided with the second pipelines 4 communicated with the vacuum tube 5. One end of the first pipeline 3, which is far away from the vacuum tube 5, forms two branches which are respectively communicated with the first heat exchangers 8 through connecting tubes 7, and each first heat exchanger 8 is communicated with one second pipeline 4 through the connecting tube 7.

Further, the distance between the first pipeline 3 and the second pipeline 4 is between 0 and D (D is the outer diameter of the vacuum tube); the central angle β between the connection point of the second conduit 4 and the vacuum tube 5 and the connection point of the first conduit 3 and the vacuum tube 5 may be an acute angle, a right angle or an obtuse angle. As shown in fig. 7, the central angle β is an acute angle, and the distance is between 0 and D/2; as shown in fig. 8, the central angle β is a right angle, i.e. the second duct 4 is tangent to the vacuum tube 5, and the distance is D/2; as shown in FIG. 9, the central angle β is an obtuse angle, and the distance is between D/2 and D.

In the embodiment, the two first heat exchangers 8 are arranged above the pipe wall of the vacuum pipe 5 for heat exchange, so that redundant heat inside the vacuum pipe is counteracted and led out as quickly as possible, and the influence of heat accumulation problems on a vehicle body and the interior of the vehicle body is reduced as far as possible.

In the embodiment, the first pipeline 3 and the first heat exchanger 8, and the first heat exchanger 8 and the second pipeline 4 are connected by the distribution of the connecting pipes 7, so as to ensure the air tightness and ensure that the inside of the connecting pipe 7 for connection maintains low vacuum pressure and air tightness.

The principle is as follows: utilize the physical phenomenon of expend with heat and contract with cold, install first pipeline 3 above vacuum tube 5 pipe wall, make the gas that the heat is more, density is lower can float into first heat exchanger 8 through first pipeline 3 nature under the condition of no power and accomplish the heat transfer, the gas of accomplishing the heat transfer can sink along with second pipeline 4 nature to accomplish the heat exchanger formula circulation of once imitating convection current.

The gas is compressed at a place with high pressure by utilizing the severe periodic fluctuation of the pressure, negative pressure is formed along with the advancing of the train 6, the pressure difference generated at the same section is larger, the hot gas enters the first heat exchanger 8 from the vacuum tube 5, and therefore the heat exchanger type circulation simulating convection is completed once.

Example three:

the embodiment provides a heat dissipation system for an underground closed pipeline, as shown in fig. 10, which includes the heat dissipation device of the first embodiment or the second embodiment, and further includes a plurality of second heat exchangers 9, where the second heat exchangers 9 are arranged along the length direction of a vacuum tube 7, and are connected to the vacuum tube 5 through a connecting tube 7.

When the heat exchanger is used, the second heat exchanger 9 is paved in a concrete structure below a track or beside the track, the heated area (inner surface area) is increased by using fins in the heat exchange tubes of the second heat exchanger 9, the heat conversion efficiency is improved, heat exchange is indirectly carried out with the outside, the problem of excessive internal heat is solved, and the influence on the internal air pressure is reduced; mainly aims at the area lacking high-speed airflow caused by train operation, namely the head and tail parts of the train 6, and simultaneously takes care of air tightness to reduce the influence of air leakage on the interior.

In this embodiment, the vacuum tube 5 is connected to the second heat exchanger 9 through the connecting tube 7, so as to ensure the air tightness and to ensure that the interior of the connecting tube 7 for connection maintains a low vacuum pressure and air tightness.

In the embodiment, the second heat exchanger 9 communicated with the vacuum pipe 5 is additionally arranged on the vacuum pipe 5 and the sealing pipe 1 or the first heat exchanger 8 communicated with the vacuum pipe 5 is additionally arranged on the upper part of the vacuum pipe for matching use, so that the hot air in the pipeline rises under the unpowered condition by utilizing natural convection and severe pressure fluctuation generated by the running of the train 6, and flows back into the vacuum pipe after being cooled, and thus, part of gas with overhigh temperature and low density can naturally exchange heat without external energy. The differential pressure through locomotive rear of a vehicle production is with hot gas fill in the inside and the outside air of heat exchanger carry out convection current and heat exchange, has effectively strengthened the air convection effect, has increased heat transfer area, has promoted the radiating effect.

Example four:

the embodiment provides a heat dissipation method for an underground closed pipeline, the heat dissipation system described in the third embodiment is adopted, a train 6 runs in a vacuum tube 5, hot gas enters a heat exchange tube of a second heat exchanger 9 from the vacuum tube 5 due to pressure difference between the head and the tail of the train, fins are arranged inside the heat exchange tube, the hot gas exchanges heat in the second heat exchanger 9, and the gas after heat exchange enters the vacuum tube 5.

Due to expansion and contraction of the gas and severe pressure fluctuation generated by the running of the train 6, hot gas flows into the first heat exchanger 8 along the first pipeline 3 in the vacuum pipe 5 for heat exchange, and cold gas after heat exchange enters the vacuum pipe 5 along the second pipeline 4.

Or because of violent pressure fluctuation generated by the running of the train 6, hot gas can quickly fill the vacuum tube 5 and the sealing tube 1, and according to the principle of expansion with heat and contraction with cold, the hot gas flows into the sealing tube 1 along the first pipeline 3 in the vacuum tube 5, flows into the second pipeline 4 along the direction of the tube bundle 2 after meeting the cooling of the tube bundle 2 in the sealing tube 1, and finally enters the vacuum tube 5.

Or the hot gas rises to the top of the sealing tube 1, flows along the inner wall of the sealing tube 1 and finally flows into the vacuum tube 5; or the hot gas rises to the top of the sealing tube 1, flows along the inner wall of the sealing tube 1 for heat exchange, then flows into the second pipeline 4, and finally flows into the vacuum tube 5.

Or the hot gas flows downwards along the direction of the first pipeline 3 after contacting the top of the sealing pipe 1, then is flushed to the pipe bundle 2 by the hot air after contacting the rising hot gas, flows into the second pipeline 4 along the pipe bundle 2, and finally enters the vacuum pipe 5.

Or the hot gas flows downwards along the direction of the first pipeline 3 after contacting the top of the sealing pipe 1, then is flushed to the top of the sealing pipe 1 by the hot air after contacting the rising hot gas, flows along the inner wall of the sealing pipe 1 for heat exchange, then flows into the second pipeline 4, and finally flows into the vacuum pipe 5.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (7)

1. A heat dissipation device for an underground closed pipeline is characterized by comprising a sealing pipe and a vacuum pipe, wherein the middle part of the sealing pipe is communicated with the vacuum pipe through a first pipeline, and two sides of the sealing pipe are respectively communicated with the vacuum pipe through second pipelines; a plurality of tube bundles which are distributed at intervals are arranged in the sealing tube; the low-pressure air in the vacuum tube can form convective circulating airflow after heat exchange is completed in the sealing tube; the distance between the first pipeline and the second pipeline is greater than 0 and less than or equal to D, wherein D is the outer diameter of the vacuum tube;

and a central angle between the connecting point of the second pipeline and the vacuum pipe and the connecting point of the first pipeline and the vacuum pipe is a right angle or an obtuse angle.

2. The heat dissipation device as claimed in claim 1, wherein a plurality of tube bundles are respectively disposed in the space between the first pipe and the two second pipes in the sealed pipe.

3. The heat dissipating device for underground closed pipes as claimed in claim 1, wherein the tube bundle is horizontally disposed or installed at a predetermined angle when the central angle is a right angle or an obtuse angle.

4. A heat dissipation device for an underground closed pipeline is characterized by comprising a first heat exchanger, a vacuum tube, a first pipeline and a second pipeline, wherein the first pipeline is connected to the middle position of the vacuum tube, and the two sides of the first pipeline are symmetrically provided with the second pipeline communicated with the vacuum tube; the first pipeline and the second pipeline are connected with the first heat exchanger respectively to form a loop; the low-pressure air in the vacuum pipe can form convective circulating airflow after heat exchange is completed in the first heat exchanger; the distance between the first pipeline and the second pipeline is greater than 0 and less than or equal to D, wherein D is the outer diameter of the vacuum tube; the central angle between the connecting point of the first pipeline and the vacuum pipe and the connecting point of the second pipeline and the vacuum pipe is a right angle or an obtuse angle.

5. The heat dissipation device as claimed in claim 4, wherein the first heat exchanger is in communication with the first pipeline and the second pipeline via a connection pipe.

6. A heat dissipation system for an underground closed pipeline, which is characterized by comprising the heat dissipation device as claimed in claim 1 or 4, wherein the vacuum tube is connected with a plurality of second heat exchangers at intervals along the axial direction of the vacuum tube.

7. A heat dissipation method for an underground closed pipeline is characterized in that the heat dissipation system as claimed in claim 6 is adopted, pressure difference is generated between the head and the tail of a train in the running process of the train, hot gas enters a second heat exchanger from a vacuum pipe for heat exchange, and the gas after heat exchange enters the vacuum pipe; due to thermal expansion and cooling of gas and severe pressure fluctuation generated by train operation, hot gas flows into the first heat exchanger for heat exchange along the first pipeline in the vacuum pipe, and cold gas after heat exchange enters the vacuum pipe along the second pipeline;

or because of the violent pressure fluctuation generated by the train operation, the hot gas fills the vacuum tube and the sealing tube, and according to the principle of expansion with heat and contraction with cold, the hot gas flows into the sealing tube along the first pipeline in the vacuum tube, flows into the second pipeline along the tube bundle direction after meeting the cooling of the tube bundle in the sealing tube, and finally enters the vacuum tube;

or the hot gas rises to the top of the sealing pipe, flows along the inner wall of the sealing pipe for heat exchange, flows into the second pipeline and finally flows into the vacuum pipe;

or the hot gas flows downwards along the direction of the first pipeline after contacting the top of the sealing pipe, then flows into the second pipeline along the pipe bundle after being contacted with the rising hot gas and is flushed to the pipe bundle by the hot air, and finally enters the vacuum pipe;

or the hot gas flows downwards along the direction of the first pipeline after contacting the top of the sealing pipe, then is flushed to the top of the sealing pipe by hot air after contacting the rising hot gas, flows along the inner wall of the sealing pipe for heat exchange, flows into the second pipeline, and finally flows into the vacuum pipe.

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