Two-phase closed thermosiphon device for power transmission and transformation foundation and construction method of two-phase closed thermosiphon device

Abstract

The invention belongs to the technical field of power transmission and transformation foundations, and provides a two-phase closed thermosiphon device for a power transmission and transformation foundation and a construction method thereof.A separator is arranged between an evaporation section and a condensation section, and the outlet end of the separator is located at the outlet position of a heat insulation section, so that evaporated working media are accumulated at the top of the heat insulation section; the problem that the inner wall at the connecting position of the condensation section and the heat insulation section is dry is solved, and the flow resistance of a condensation working medium is reduced; a gas-liquid diverter is arranged in the heat insulation section, the shearing stress between a gas phase and a liquid film is reduced to the maximum extent through gas-liquid diverting, the working medium circulation effect is further guaranteed by reducing gas-liquid interaction, the frozen soil rapid temperature rising speed is increased, and the device is used for a power transmission and transformation foundation.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transmission and transformation foundations, and in particular relates to a two-phase closed thermosiphon device for power transmission and transformation foundations and a construction method thereof. Background Art

[0002] Problems such as uneven frost heave, thaw settlement, and rheology in the power transmission and transformation foundation are not conducive to foundation stability and pose a huge safety hazard to power transmission and transformation. The bearing capacity of the foundation depends on the adhesion between the foundation and the surrounding permafrost. However, with global warming, thermal disturbances caused by tower base construction, and thermal effects of concrete foundations, the permafrost around the foundation is prone to degradation, causing this adhesion to deteriorate.

[0003] The application of two-phase closed thermosyphons (TPCTs) in permafrost engineering can address the problem of deteriorating adhesion between foundations and surrounding frozen soil. However, traditional two-phase closed thermosyphons are not suitable for power transmission and transformation foundations. This is mainly due to the complex and diverse construction environments and special requirements for stability. If traditional two-phase closed thermosyphons are used, their heat dissipation effect is poor. Specifically, the inner wall at the connection between the condensing section and the adiabatic section is often relatively dry, increasing the flow resistance of the condensing working fluid and reducing the working fluid circulation effect. In addition, gas-liquid interaction exists between the rising gaseous working fluid and the descending liquid working fluid in the adiabatic section, reducing the circulation effect of the gaseous working fluid rising and the liquid working fluid descending, thus failing to meet the goal of rapidly cooling frozen soil. Furthermore, the actual conditions of the transmission and transformation pile foundations in different environments are not taken into consideration when laying out thermosyphons. This can lead to cost waste due to excessive layouts, or ineffective cooling due to too few layouts. Summary of the Invention

[0004] In order to solve the above problems, the present invention proposes a two-phase closed thermal siphon device for power transmission and transformation foundations and a construction method thereof. A separator is provided between the evaporation section and the condensation section, and the outlet end of the separator is located at the outlet position of the insulation section, so that the evaporated working fluid accumulates at the top of the insulation section, solving the problem of inner wall drying at the connection position of the condensation section and the insulation section, and reducing the flow resistance of the condensed working fluid; combined with a gas-liquid diverter provided in the insulation section, the shear stress between the gas phase and the liquid film is minimized through gas-liquid diversion, and the working fluid circulation effect is further guaranteed by reducing the gas-liquid interaction, and the rapid warming rate of frozen soil is improved, which is used in power transmission and transformation foundations.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a two-phase closed thermosyphon device for power transmission and transformation infrastructure, which adopts the following technical solutions: A two-phase closed thermosiphon device for power transmission and transformation foundation, comprising an evaporation section, an insulation section and a condensation section connected to each other; A separator is further provided between the evaporation section and the condensation section, and the outlet end of the separator is located at the outlet position of the insulation section; a gas-liquid diverter is provided in the insulation section, which reduces the shear stress between the gas phase and the liquid film through gas-liquid diversion, thereby reducing gas-liquid interaction.

[0006] Furthermore, the gas-liquid splitter includes a tapered tube section close to the evaporation section and a straight tube section away from the evaporation section.

[0007] Furthermore, the end of the tapered tube section with a larger opening faces the tapered tube section.

[0008] Furthermore, the length of the tapered pipe section is shorter than the length of the straight pipe section.

[0009] Furthermore, the outer diameter of the straight pipe section is smaller than the inner diameter of the insulation section.

[0010] Furthermore, a gap is provided between the maximum outer diameter edge of the conical tube section and the inner wall of the insulation section.

[0011] Furthermore, the inlet end of the gas-liquid separator is located at the evaporation section; and the gas-liquid separator is an arc-shaped tube.

[0012] Furthermore, a working medium is provided in the evaporation section, and the working medium is a nano-refrigerant including R600a, polyol ester oil and CuO.

[0013] In order to achieve the above-mentioned object, in a second aspect, the present invention further provides a construction method of a two-phase closed thermosiphon device for a power transmission and transformation foundation, which adopts the following technical solution: A construction method for a two-phase closed thermosyphon device for a power transmission and transformation foundation uses the two-phase closed thermosyphon device for a power transmission and transformation foundation as described in the first aspect, including determining the number and layout of the thermosyphons according to the temperature and ice content of frozen soil in different environments.

[0014] Furthermore, when the temperature is greater than or equal to the temperature and humidity preset values, and the ice content of the frozen soil is less than or equal to the content preset value, a thermosiphon is installed at each corner of the extended foundation, and two thermosiphons are installed around the pile foundation; when the temperature is less than the temperature and humidity preset values, and the ice content of the frozen soil is greater than the content preset value, a thermosiphon is installed at each diagonal corner of the extended foundation, and a thermosiphon is installed around the pile foundation.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, a separator is provided between the evaporation section and the condensation section, and the outlet end of the separator is located at the outlet position of the insulation section, so that the evaporated working medium accumulates at the top of the insulation section, solving the problem of drying of the inner wall at the connection position of the condensation section and the insulation section, and reducing the flow resistance of the condensed working medium; combined with the gas-liquid diverter provided in the insulation section, the shear stress between the gas phase and the liquid film is minimized through gas-liquid diversion, and the working medium circulation effect is further guaranteed by reducing the gas-liquid interaction, thereby improving the frozen soil cooling rate, and is suitable for power transmission and transformation foundations.

[0016] 2. In the present invention, the number and layout of thermosiphons are determined according to the temperature and ice content of frozen soil in different environments. Specifically, when the temperature is greater than or equal to the temperature and humidity preset values, and the ice content of frozen soil is less than or equal to the content preset value, a thermosiphon is installed at each corner of the extended foundation, and two thermosiphons are installed around the pile foundation. By increasing the number of thermosiphons, the cooling effect of the frozen soil is ensured; when the temperature is less than the temperature and humidity preset values, and the ice content of frozen soil is greater than the content preset value, a thermosiphon is installed at each diagonal corner of the extended foundation, and a thermosiphon is installed around the pile foundation. By reducing the number of thermosiphons, the cost is reduced while ensuring that the frozen soil will not fail due to temperature increase.

[0017] 3. This embodiment uses a nano-refrigerant consisting of R600a, polyol ester oil, and CuO. R600a does not damage the ozone layer, has no greenhouse effect, and is environmentally friendly. Compared with traditional Freon refrigerants, it is more in line with the principles of sustainable development and has a wider range of applications in the future. Furthermore, the nano-refrigerant can more effectively enhance the boiling and condensing processes, which is beneficial to heat transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the specification of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments and descriptions of this embodiment are used to explain this embodiment and do not constitute an improper limitation on this embodiment.

[0019] Figure 1 Schematic diagram of the device structure of Example 1 of the present invention; Figure 2 The first situation of Example 1 of the present invention is to expand the layout of the thermosiphon tubes at the base position; Figure 3 This is the layout of the thermosiphon at the pile foundation position in the first case of Example 1 of the present invention; Figure 4 The second situation of Example 1 of the present invention expands the layout of the thermosiphon tubes at the base position; Figure 5 This is the layout of the thermosiphon at the pile foundation position in the second case of Example 1 of the present invention; Among them, 1. Evaporation section; 2. Adiabatic section; 3. Condensation section; 4. Diverter; 401. Conical pipe section; 402. Straight pipe section; 5. Gas-liquid separator; 6. Working fluid. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0022] The bearing capacity of the foundation depends on the bonding force between the foundation and the surrounding permafrost. However, with global warming, thermal disturbances caused by tower base construction, and thermal effects of the concrete foundation, the permafrost around the foundation is prone to degradation, causing this bonding effect to deteriorate.

[0023] Example 1: As recorded in the background technology, the power transmission and transformation foundation has special requirements such as complex and diverse construction environments and high stability requirements. If a traditional two-phase closed thermal siphon is used, its heat dissipation effect is poor. Specifically, at the connection position of the condensation section and the insulation section, the inner wall is often relatively dry, which increases the flow resistance of the condensing working fluid and reduces the working fluid circulation effect. In addition, there is a gas-liquid interaction between the rising gaseous working fluid and the descending liquid working fluid in the insulation section, which reduces the circulation effect of the rising gaseous working fluid and the descending liquid working fluid. It cannot meet the purpose of rapid cooling of frozen soil, making the traditional two-phase closed thermal siphon unsuitable for power transmission and transformation foundations.

[0024] To address the above issues, this embodiment provides a two-phase closed thermosyphon device for a power transmission and transformation foundation. The device features structural improvements on the traditional two-phase closed thermosyphon, enhancing its ability to improve thermal stability and adopting a new, green and environmentally friendly working fluid. Finally, based on the characteristics of the power transmission and transformation foundation, a new two-phase closed thermosyphon layout scheme is provided. The number of heat pipes to be installed and the layout method vary depending on the frozen soil conditions and foundation type.

[0025] like Figure 1 As shown, the thermosiphon device includes an interconnected evaporation section 1, an adiabatic section 2, and a condensation section 3, a flow splitter 4, a gas-liquid separator 5, and a working medium 6. The flow splitter 4 includes an interconnected tapered tube section 401 and a straight tube section 402. The evaporation section 1 and the condensation section 3 can also be referred to as an evaporator and a condenser.

[0026] Optionally, depending on the type and burial depth of the power transmission and transformation foundation, the length of the evaporation section 1 is set to 8m, the length of the condensation section 3 is set to 4m, the length of the insulation section 2 is set to 2m, the inner diameter of the pipe is set to 0.04m, the outer diameter of the pipe is set to 0.05m, and the shell material can be copper, steel or aluminum.

[0027] The evaporation section 1 can be constructed with materials or fins with high thermal conductivity to enhance heat absorption, depending on actual needs. The condensation section 3 can also utilize fins and other features to increase the heat transfer area. In colder environments, the material or coating can be modified to prevent frost accumulation. The insulation section 2 can be equipped with an insulation layer to reduce heat loss, and materials such as stainless steel or titanium can be used to enhance durability and corrosion resistance.

[0028] During operation, when the entire thermosyphon device's main structure is located within permafrost and the air temperature is lower than the soil temperature, the TPCT begins to operate. Heat from the permafrost evaporates the working medium 6 into a thin layer of working fluid at the evaporation section 1. The vapor then flows upward and condenses in the condensation section 3 of the pipe, releasing the transported heat into the atmosphere. The condensed liquid then flows downward to form a liquid film, ultimately returning to the evaporation section 1, continuing the evaporation-condensation cycle. When the air temperature rises above the soil temperature, the evaporation-condensation cycle ceases. Therefore, the use of thermosyphons results in more efficient heat loss from the underlying permafrost and enhances the strength of the surrounding permafrost soil.

[0029] The gas-liquid diverter 4 is disposed within the insulating section 2; the gas-liquid diverter 4 comprises a tapered tube section 401 proximal to the evaporation section 1, and a straight tube section 402 distal to the evaporation section 1. The larger end of the tapered tube section 401 faces the tapered tube section 1. The length of the tapered tube section 401 is shorter than the length of the straight tube section 402. The outer diameter of the straight tube section 402 is smaller than the inner diameter of the insulating section 2. A gap is provided between the maximum outer diameter edge of the tapered tube section 401 and the inner wall of the insulating section 2, ensuring liquid film formation.

[0030] Optionally, the straight pipe section 402 has an outer diameter of 16 mm and an inner diameter of 15 mm. The tapered pipe section 401 is located at the beginning of the evaporation section 1 and can be secured to the main pipe of the evaporation section 1 or the insulation section 2 using a connecting bracket or connecting ribs. The material used can be copper, steel, or aluminum, consistent with the shell material. Its primary function is to separate the main pipe path, minimizing the shear stress between the vapor phase rising from the evaporator and the liquid film returning from the condenser. This allows the vapor to travel from the evaporator to the condenser through the tapered pipe within the main pipe, causing the liquid film to condense on the inner wall of the main pipe, thereby minimizing vapor-liquid interaction and improving TPCT thermal performance and temperature distribution.

[0031] The separator 5 is also provided between the evaporation section 1 and the condensation section 3, and the outlet end of the separator 5 is located at the outlet position of the insulation section 2. The inlet end of the gas-liquid separator 5 is located at the evaporation section 1. The gas-liquid separator 5 is an arc-shaped tube. The separator 5 is composed of a copper tube and needs to be welded on the main TPCT, and the welding position extends from the evaporator to the insulation section. This tube is used for separate liquid return, and the downward tube in the separator 5 helps the evaporated fluid to flow upward, so that the evaporated working medium accumulates at the top of the insulation section, solving the drying problem of the traditional two-phase closed thermal siphon evaporator. The separator 5 ensures the formation of a continuous liquid film on the inner surface of the TPCT by matching the downward liquid flow rate with the evaporation rate, thereby minimizing the flow resistance and improving the thermal performance and temperature distribution of the TPCT.

[0032] This embodiment uses the separator 5 and the gas-liquid diverter 4. The separator 5 ensures the formation of a continuous liquid film on the inner surface of the TPCT, minimizing the flow resistance. The gas-liquid diverter 4 minimizes the shear stress between the gas phase rising from the evaporator and the liquid film returning from the condenser, thereby minimizing the gas-liquid interaction. Both improve the heat transfer efficiency of the TPCT and enable it to have a better cooling effect on permafrost.

[0033] The performance of traditional TPCTs depends heavily on the appropriate refrigerant within the sealing system. These refrigerants fall into three main categories: inorganic coolants, Freon refrigerants, and other organic refrigerants. Some of these refrigerants pose potential environmental risks and are detrimental to their sustainable development. Therefore, the development of novel TPCT structures and environmentally friendly refrigerants is crucial.

[0034] Working fluid 6 refers to a refrigerant capable of undergoing phase changes at low and high temperatures. Optionally, in this embodiment, working fluid 6 utilizes a nano-refrigerant (R600a / polyol ester oil / CuO) with a 10% liquid filling ratio. This nano-refrigerant effectively enhances the boiling and condensing processes. Furthermore, the added nano-CuO additive significantly increases the pressure differential, which facilitates thermosiphoning. The use of nano-refrigerant (R600a / polyol ester oil / CuO) is environmentally friendly and ozone-safe, unlike traditional CFC-based refrigerants, which are more sustainable and have broader future applications. Furthermore, the nano-refrigerant effectively enhances the boiling and condensing processes, which facilitates heat transfer.

[0035] R600a is a new hydrocarbon refrigerant with excellent performance. It refers to 99.5% pure isobutylene, derived from natural ingredients. It is ozone-safe, has no greenhouse effect, and is environmentally friendly. Polyol ester (POE) oil is added to pure R600a as a lubricant at a 1% mass fraction to form a baseline mixture. CuO refers to copper oxide nanoparticles approximately 40 nm in size. Its parameters can be controlled as shown in Table 1 below: Table 1 Specifications of CuO nanoparticles

[0036] In this embodiment, the nano-refrigerant (R600a / polyol ester oil / CuO) was prepared by dispersing 0.5%, 1%, and 1.5% by mass of CuO nanoparticles in polyol ester oil, controlled by a digital electronic balance with a maximum error of 0.1 mg. An ultrasonic device was then used to prepare a mixture of the oil and nanoparticles at 400 W and 20 kHz for one hour to form a well-dispersed mixture. The polyol ester oil / CuO mixture was then injected into pure refrigerant R600a, ensuring that no sedimentation or significant accumulation was observed within approximately 12 hours after the dispersion process.

[0037] This embodiment also provides a novel arrangement for a two-phase closed thermosyphon device for power transmission and transformation pile foundations. This arrangement, tailored to the characteristics of power transmission and transformation foundations, provides a novel TPCT layout scheme, resulting in improved operating efficiency and adaptability to a variety of environmental conditions. Specifically, the number and layout of thermosyphons are determined based on the temperature and ice content of the frozen soil in different environments. Specifically, when the temperature is greater than or equal to the preset temperature and humidity values, and the frozen soil ice content is less than or equal to the preset ice content value, a thermosyphon is installed at each corner of the extended foundation, and two thermosyphons are installed around the pile foundation. By increasing the number of thermosyphons, the frozen soil is cooled. When the temperature is less than the preset temperature and humidity values, and the frozen soil ice content is greater than the preset ice content value, a thermosyphon is installed at each diagonal corner of the extended foundation, and one thermosyphon is installed around the pile foundation. By reducing the number of thermosyphons, costs are reduced while ensuring that the frozen soil does not fail due to temperature increases. The issue here can refer to the maximum temperature of the frozen soil or the average temperature over a certain period of time. The ice content of permafrost refers to the ice content or the proportion of ice content in a certain volume of soil.

[0038] Optional, such as Figure 2 and Figure 3 As shown, the number and arrangement of installations are as follows: in warm (≥-1°C) and permafrost areas with high ice content, install a TPCT at each corner of the extended foundation and install two thermosiphons around the pile foundation, ensuring that the TPCT is close to the pile body, and the line connecting the two TPCT positions needs to pass through the center of the pile foundation. Figure 4 and Figure 5 As shown in the figure, in cold (<-1°C) and permafrost areas with high ice content, two TPCTs are installed at the corners of the extended foundation. The line connecting the two TPCT positions needs to pass through the center of the extended foundation. A TPCT is installed around the pile foundation. The TPCT is close to the pile body and is located at a 45° angle to the outside of the pile. TPCTs are not required under other frozen soil conditions.

[0039] It is worth noting that the cooling effect of TPCT is also affected by the aspect ratio (ratio of evaporator section length to tube inner diameter), filling ratio, tilt angle, and air and ground temperature. It needs to be determined according to the specific site conditions and needs, which will not be elaborated here.

[0040] Example 2: This embodiment provides a construction method for a two-phase closed thermosyphon device for a power transmission and transformation foundation, using the two-phase closed thermosyphon device for a power transmission and transformation foundation as described in Example 1, including determining the number and layout of the thermosyphons according to the temperature and ice content of the frozen soil in different environments.

[0041] Furthermore, when the temperature is greater than or equal to the temperature and humidity preset values, and the ice content of the frozen soil is less than or equal to the content preset value, a thermosiphon is installed at each corner of the extended foundation, and two thermosiphons are installed around the pile foundation; when the temperature is less than the temperature and humidity preset values, and the ice content of the frozen soil is greater than the content preset value, a thermosiphon is installed at each diagonal corner of the extended foundation, and a thermosiphon is installed around the pile foundation.

[0042] The above description is merely a preferred embodiment of this embodiment and is not intended to limit this embodiment. Those skilled in the art will readily appreciate that this embodiment may be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this embodiment shall be within the scope of protection of this embodiment.

Claims

1. A two-phase closed thermosyphon device for power transmission and transformation foundation, characterized in that: It includes an evaporation section, an adiabatic section and a condensation section that are interconnected; A separator is further provided between the evaporation section and the condensation section, and the outlet end of the separator is located at the outlet position of the insulation section; a gas-liquid diverter is provided in the insulation section, which reduces the shear stress between the gas phase and the liquid film through gas-liquid diversion, thereby reducing gas-liquid interaction.

2. A two-phase closed thermosyphon device for power transmission and transformation infrastructure according to claim 1, characterized in that: The gas-liquid splitter includes a tapered tube section close to the evaporation section and a straight tube section away from the evaporation section.

3. A two-phase closed thermosyphon device for power transmission and transformation infrastructure according to claim 2, characterized in that: The end of the tapered tube section with a larger opening faces the tapered tube section.

4. A two-phase closed thermosyphon device for power transmission and transformation infrastructure according to claim 2, characterized in that: The length of the tapered pipe section is smaller than the length of the straight pipe section.

5. A two-phase closed thermosyphon device for power transmission and transformation infrastructure according to claim 2, characterized in that: The outer diameter of the straight pipe section is smaller than the inner diameter of the insulation section.

6. A two-phase closed thermosyphon device for power transmission and transformation infrastructure according to claim 2, characterized in that: A gap is set between the maximum outer diameter edge of the cone tube section and the inner wall of the insulation section.

7. A two-phase closed thermosyphon device for power transmission and transformation infrastructure according to claim 1, characterized in that: The inlet end of the gas-liquid separator is located at the evaporation section; the gas-liquid separator is an arc-shaped tube.

8. The two-phase closed thermosyphon device for power transmission and transformation infrastructure according to claim 1, characterized in that: A working medium is arranged in the evaporation section, and the working medium adopts nano-refrigerant, including R600a, polyol ester oil and CuO.

9. A construction method for a two-phase closed thermosyphon device for power transmission and transformation foundation, characterized in that: A two-phase closed thermosyphon device for a power transmission and transformation foundation as described in any one of claims 1 to 8 is used, including determining the number and layout of the thermosyphons according to the temperature and ice content of frozen soil in different environments.

10. The construction method of a two-phase closed thermosyphon device for power transmission and transformation foundation according to claim 1, characterized in that: When the temperature is greater than or equal to the temperature and humidity preset values, and the ice content of the frozen soil is less than or equal to the content preset value, a thermosiphon is installed at each corner of the extended foundation, and two thermosiphons are installed around the pile foundation; when the temperature is less than the temperature and humidity preset values, and the ice content of the frozen soil is greater than the content preset value, a thermosiphon is installed at each diagonal corner of the extended foundation, and a thermosiphon is installed around the pile foundation.

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