A phase change enhanced heat exchange device for energy tunnels

Abstract

The utility model discloses a kind of phase-change enhanced heat exchange devices for energy tunnel, it is related to the technical field of tunnel building, and phase-change enhanced heat exchange device includes: circulating heat exchange pipe, circulating heat exchange pipe is used for circulating heat exchange medium flow, circulating heat exchange pipe is embedded in secondary lining and extends along secondary lining;Heat conduction part, heat conduction part is embedded in secondary lining, one end of heat conduction part is located between circulating heat exchange pipe and secondary lining outside and forms thermal contact with circulating heat exchange pipe, one end of heat conduction part away from circulating heat exchange pipe extends along the thickness direction of secondary lining towards rock-soil body;Wherein, at least part of circulating heat exchange pipe extends parallel to the circumferential side of secondary lining;Heat conduction part is provided with multiple, multiple heat conduction parts are sequentially arranged along the extension direction of circulating heat exchange pipe.The utility model can form low thermal resistance heat transfer path between circulating heat exchange pipe and rock-soil body, improve unit secondary lining area heat exchange efficiency, reduce the risk of cold and heat accumulation in the long-term operation of energy tunnel.

Description

Technical Field

[0001] This utility model relates to the technical field of tunnel construction, and in particular to a phase change enhanced heat exchange device for energy tunnels. Background Technology

[0002] Tunnels typically consist of initial support and secondary lining. The initial support is placed inside the rock and soil mass, while the secondary lining is placed inside the initial support. To maintain the temperature inside the tunnel within a suitable range, heat exchange structures are required to exchange heat with the surrounding rock and soil mass.

[0003] Energy tunnels are a typical form of shallow geothermal utilization. The basic idea is to embed circulating heat exchange pipes within the tunnel lining, giving the tunnel structure the functions of load-bearing, protection, and geothermal heat exchange. The circulating heat exchange medium flows within the heat exchange pipes and exchanges heat with the tunnel lining and surrounding soil and rock. The circulating heat exchange pipes are generally located inside the concrete lining. Polyethylene pipes, cross-linked polyethylene pipes, HDPE pipes, or other plastic circulating heat exchange pipes are fixed within the secondary lining reinforcement cage, and then concrete is poured to form an integral lining structure. Heat must pass through the concrete lining before it can be transferred to the outer soil and rock.

[0004] Because concrete lining typically has a low thermal conductivity and limited heat transfer capacity, coupled with its considerable thickness, a high thermal resistance exists between the heat exchange tubes and the surrounding rock. During long-term operation, localized hot and cold accumulation zones easily form around the heat exchange tubes, gradually reducing the temperature difference between the circulating heat exchange medium and the lining, leading to a decrease in heat exchange efficiency. In summer cooling conditions, heat cannot dissipate quickly enough into the initial support and soil mass, causing a rapid temperature rise near the circulating heat exchange tubes. This results in increased outlet water temperature, decreased heat transfer rate per unit area, and reduced system continuous operation capacity. Similarly, in winter heating conditions, a rapid temperature drop around the heat exchange tubes can trigger concentrated localized thermal disturbances, affecting the thermal recovery process of the energy tunnel. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a phase change enhanced heat exchange device for energy tunnels, which can form a low thermal resistance heat transfer path between the circulating heat exchange tube and the rock and soil, improve the heat exchange efficiency per unit secondary lining area, and reduce the risk of heat and cold accumulation during the long-term operation of energy tunnels.

[0006] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0007] This utility model provides a phase change enhanced heat exchange device for an energy tunnel, the energy tunnel including an initial support disposed on the inner side of the rock and soil body and a secondary lining disposed on the inner side of the initial support, the phase change enhanced heat exchange device including:

[0008] A circulating heat exchange tube is used to supply the flow of circulating heat exchange medium. The circulating heat exchange tube is embedded in the secondary lining and extends along the secondary lining.

[0009] A heat-conducting element is embedded within the secondary lining. One end of the heat-conducting element is located between the circulating heat exchange tube and the outer side of the secondary lining, forming thermal contact with the circulating heat exchange tube. The end of the heat-conducting element away from the circulating heat exchange tube extends towards the soil and rock mass along the thickness direction of the secondary lining. At least a portion of the circulating heat exchange tube extends parallel to the periphery of the secondary lining. Multiple heat-conducting elements are provided, and the multiple heat-conducting elements are arranged sequentially along the extension direction of the circulating heat exchange tube.

[0010] The heat-conducting component includes a phase change heat pipe, which includes a heat pipe shell, a capillary wick, and a phase change medium. The heat pipe shell forms a sealed cavity, and the phase change medium is encapsulated within the cavity of the heat pipe shell. The capillary wick is disposed within the heat pipe shell and extends along the inner wall of the cavity of the heat pipe shell. The inner side of the capillary wick encloses and forms a vapor channel extending axially along the heat pipe shell.

[0011] In this scheme, circulating heat exchange pipes are embedded in the secondary lining. The circulating heat exchange medium flowing in the circulating heat exchange pipes enables the circulating heat exchange pipes to exchange heat with the secondary lining. The heat-conducting element extends towards the rock and soil mass, forming a low thermal resistance heat transfer path between the circulating heat exchange pipe and the outer side of the secondary lining. This can effectively reduce the thermal resistance of the lining concrete, allowing heat to quickly cross the main thermal resistance area in the thickness direction of the secondary concrete lining. The internal temperature gradient of the heat-conducting element is small, and it can be used as a near-isothermal passive heat transfer channel, reducing the temperature difference between the area near the circulating heat exchange pipe and the outer area of ​​the secondary lining, improving the temperature field distribution in the secondary lining and the surrounding rock, and significantly improving the heat exchange efficiency and overall heat exchange capacity of the energy tunnel.

[0012] At least a portion of the circulating heat exchange pipes extend parallel to the periphery of the secondary lining, allowing them to be embedded parallel within the secondary lining for heat exchange. This improves the uniformity of heat exchange between the circulating heat exchange pipes and the secondary lining, adapts to the elongated structure of the secondary lining, and can be installed simultaneously with the secondary lining pouring. This minimizes disturbance to the original support structure of the energy tunnel and ensures strong construction compatibility. Multiple heat-conducting components are arranged sequentially along the extension direction of the circulating heat exchange pipes, forming continuous heat-conducting nodes along the heat exchange path. This expands the effective heat exchange area, eliminates heat exchange blind spots, and ensures the uniformity and stability of the heat exchange process. The heat-conducting components include phase change heat pipes, which utilize the latent heat of phase change in the phase change medium to transfer heat. Their thermal conductivity is far higher than that of traditional solid metal heat-conducting components, enabling rapid, long-distance heat transfer and significantly enhancing the heat exchange capacity between the soil and rock mass and the circulating heat exchange pipes, thereby improving the heat exchange efficiency of the energy tunnel.

[0013] During summer cooling operation, the circulating heat exchanger tubes absorb heat from the secondary lining. The temperature of the circulating heat exchange medium is relatively high. The heat-conducting components are in thermal contact with the circulating heat exchanger tubes, and the heat in the circulating heat exchanger tubes is transferred to the heat-conducting components. The heat is then released by the heat-conducting components to the outside of the secondary lining, the initial support, or the soil and rock mass, reducing the heat accumulation at the circulating heat exchanger tubes. This allows the circulating heat exchange medium to continuously absorb heat from the inside of the secondary lining, thus lowering the temperature of the energy tunnel. During winter heating operation, the heat-conducting components absorb heat from the outside of the secondary lining, the initial support, or the soil and rock mass and transfer it to the circulating heat exchanger tubes. The temperature of the circulating heat exchange medium rises, and the circulating heat exchanger tubes continuously release heat to the inside of the secondary lining to increase the temperature inside the energy tunnel.

[0014] Specifically, in summer cooling mode, the circulating heat exchange medium enters the circulating heat exchange tube at a higher temperature, and the heat is transferred to the secondary lining surrounding the circulating heat exchange tube. The end of the phase change heat pipe closest to the circulating heat exchange tube absorbs heat from the vicinity of the circulating heat exchange tube. The phase change medium in this end of the phase change heat pipe absorbs heat and evaporates. The resulting vapor migrates along the vapor channel to the other end of the phase change heat pipe and condenses and releases heat in the end of the phase change heat pipe closest to the soil. The condensed liquid phase change medium flows back to the end of the phase change heat pipe closest to the circulating heat exchange tube under the action of a capillary, forming a continuous phase change heat transfer cycle. In winter heating mode, the phase change medium in the end of the phase change heat pipe closest to the soil absorbs heat and evaporates from the soil. The resulting vapor migrates along the vapor channel to the other end of the phase change heat pipe and condenses and releases heat in the end of the phase change heat pipe closest to the circulating heat exchange tube. The condensed liquid phase change medium flows back to the end of the phase change heat pipe closest to the soil under the action of a capillary.

[0015] Therefore, through the combination of capillary core and steam channel, the automatic circulation and reflux of phase change medium can be realized. It can operate continuously and stably without additional power equipment. The structure is simple, the operation is highly reliable, and it is suitable for long-term, low-maintenance use scenarios in energy tunnels.

[0016] Furthermore, the circulating heat exchange tube is any one of U-shaped tube, serpentine tube, circumferential coil, axial straight tube group or multi-loop parallel tube group.

[0017] In this scheme, the circulating heat exchange tube can be one of a variety of tube types, such as U-shaped tube, serpentine tube, circumferential coil, axial straight tube group, and multi-loop parallel tube group. The type can be flexibly selected according to the cross-sectional size of the secondary lining, the design heat exchange power, and the on-site construction conditions to meet the heat exchange needs of energy tunnels under different working conditions.

[0018] Furthermore, the circulating heat exchange tubes are evenly arranged on a curved surface parallel to the periphery of the secondary lining.

[0019] In this design, the circulating heat exchange tubes are evenly arranged on a curved surface parallel to the periphery of the secondary lining. This allows for full utilization of the structural space within the secondary lining to lay out the heat exchange pipes, maximizing the cross-section of the secondary lining and increasing the overall heat exchange area. The uniform curved surface arrangement ensures a uniform distribution of the contact interface between the circulating heat exchange tubes and the lining, avoiding uneven temperature distribution in the secondary lining caused by localized concentration of circulating heat exchange tubes.

[0020] Furthermore, the plurality of the heat-conducting elements are arranged in a uniform array on the curved surface of the circulating heat exchange tube arrangement.

[0021] In this design, multiple heat-conducting components are uniformly arrayed on the curved surface of the circulating heat exchanger tubes, forming a uniformly distributed heat-conducting network across the entire lining surface. This efficiently and uniformly transfers heat between the soil / rock mass and the circulating heat exchanger tubes, eliminating weak heat exchange areas in the secondary lining and further improving overall heat exchange efficiency and uniformity. The uniform array arrangement also ensures more balanced stress distribution within the secondary lining, reducing the negative impact of embedded heat-conducting components on the structural mechanical properties of the secondary lining and guaranteeing its load-bearing capacity.

[0022] Furthermore, the angle between the heat-conducting element and the thickness direction of the secondary lining is no greater than 30°.

[0023] In this scheme, the angle between the heat-conducting component and the thickness direction of the secondary lining is no more than 30°, so that the heat-conducting component is basically arranged along the thickness direction of the lining. This can effectively shorten the heat conduction path inside the secondary lining, reduce the thermal resistance, and enhance the heat transfer efficiency of the heat-conducting component.

[0024] Furthermore, multiple heat-conducting components are arranged at uniform intervals along the circumference of the secondary lining to form heat-conducting component groups, and multiple heat-conducting component groups are arranged at uniform intervals along the axial direction of the secondary lining, with the spacing between adjacent heat-conducting component groups being 0.6m–1.8m.

[0025] In this design, each group of heat-conducting components is evenly spaced along the axial direction, forming a grid-like heat-conducting system across the entire circumferential and axial range of the secondary lining. This further avoids areas with insufficient local heat transfer. The spacing between adjacent heat-conducting component groups is controlled between 0.6m and 1.8m. This spacing ensures sufficient coverage density of the heat-conducting components, avoids heat transfer blind spots, and controls the total number of heat-conducting components used. This balances the improvement in heat transfer performance with material and construction costs, preventing damage to the secondary lining structure due to excessively dense spacing and poor heat transfer performance due to excessively sparse spacing. It also reduces the reduction in heat transfer contribution caused by overlapping heat-affected zones of the heat-conducting components and minimizes thermal interference caused by overly dense arrangement of heat-conducting components.

[0026] Furthermore, the heat pipe housing is made of copper, stainless steel, or aluminum alloy, and the phase change medium includes one, two, or more of water, ethanol, and acetone.

[0027] In this design, the heat pipe shell is made of copper, stainless steel, or aluminum alloy, offering excellent thermal performance and further reducing interfacial thermal resistance. The shell also exhibits strong corrosion resistance, adapting to the complex environment of tunnels with humid and corrosive media, thus extending the device's service life. The phase change medium can be water, ethanol, or acetone, allowing for selection of a suitable medium for different temperature ranges. This ensures the phase change process proceeds efficiently at the target temperature, enhancing the phase change heat pipe's adaptability to different regions and ground temperatures.

[0028] Furthermore, the heat-conducting element is embedded in the secondary lining, and the distance between the end of the heat-conducting element close to the circulating heat exchange tube and the outer wall of the circulating heat exchange tube is 0mm-100mm, and the distance between the end of the heat-conducting element away from the circulating heat exchange tube and the outer side of the secondary lining is 0mm-100mm.

[0029] In this design, the heat-conducting component is embedded within the secondary lining. This allows the component to be integrally cast and fixed within the secondary lining during construction, eliminating the need for further construction on the initial support. It also prevents the component from protruding through the secondary lining, thus protecting the initial support, waterproofing membrane, and other tunnel structures, ensuring the tunnel's support safety and waterproofing performance. The distance between the end of the heat-conducting component closest to the circulating heat exchanger and the outer wall of the tube is controlled between 0mm and 100mm. This ensures efficient heat transfer between them and prevents excessive heat resistance due to larger gaps, guaranteeing efficient heat transfer to the circulating heat exchanger. The distance between the end of the heat-conducting component furthest from the circulating heat exchanger and the outer side of the secondary lining is controlled between 0mm and 100mm, allowing the component to be as close as possible to the soil and rock mass for maximum heat exchange.

[0030] Furthermore, the secondary lining is arched, and the heat-conducting element extends radially along the secondary lining.

[0031] In this design, the radially extending arrangement of the heat-conducting components for the arched secondary lining allows them to be laid along the shortest path of the secondary lining thickness, shortening the heat conduction distance and reducing thermal resistance. The radially arranged heat-conducting components align with the stress direction of the arched secondary lining, minimizing structural stress disturbance and reducing the likelihood of weakening its load-bearing capacity, thus ensuring the mechanical safety of the energy tunnel support structure.

[0032] In summary, this utility model has the following beneficial effects:

[0033] In this phase change enhanced heat exchange device, a circulating heat exchange tube is embedded in the secondary lining. The circulating heat exchange medium flowing in the circulating heat exchange tube enables the circulating heat exchange tube to exchange heat with the secondary lining. The heat-conducting element extends towards the rock and soil mass, forming a low thermal resistance heat transfer path between the circulating heat exchange tube and the outer side of the secondary lining. This can effectively reduce the thermal resistance of the lining concrete, allowing heat to quickly cross the main thermal resistance area in the thickness direction of the secondary concrete lining, reducing the temperature difference between the area near the circulating heat exchange tube and the outer area of ​​the secondary lining, and improving the temperature field distribution in the secondary lining and the surrounding rock. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of an energy tunnel according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of a circulating heat exchange tube according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the structure of a circulating heat exchange tube and a heat-conducting component according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure of the circulating heat exchange tube and heat conduction element when installed in a secondary lining according to an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of a heat-conducting component according to an embodiment of the present invention;

[0039] In the picture:

[0040] 1000 Energy Tunnel; 100 Rock and Soil Mass; 200 Initial Support; 300 Secondary Lining; 400 Phase Change Enhanced Heat Exchange Device; 410 Circulating Heat Exchanger Tube; 411 First Tube Section; 412 Second Tube Section; 420 Heat Conductor; 421 Heat Pipe Shell; 422 Capillary Wafer; 423 Steam Channel. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings.

[0042] This embodiment provides a phase change enhanced heat exchange device 400 for energy tunnels, referring to... Figure 1 and Figure 2The energy tunnel 1000 includes an initial support 200 disposed inside the rock and soil mass 100 and a secondary lining 300 disposed inside the initial support 200. Both the initial support 200 and the secondary lining 300 are coaxial with the inner cavity of the energy tunnel 1000 to support the energy tunnel 1000 inside the rock and soil mass 100. In this embodiment, the inner cavity of the energy tunnel 1000 is specifically arched, and correspondingly, the initial support 200 and the secondary lining 300 are arched. In addition, in other embodiments, the inner cavity of the energy tunnel 1000 may also be rectangular, horseshoe-shaped, or other suitable shapes, and correspondingly, the shapes of the initial support 200 and the secondary lining 300 are adapted to the shape of the inner cavity of the energy tunnel 1000.

[0043] Reference Figure 2 and Figure 3 The phase change enhanced heat exchange device 400 includes a circulating heat exchange tube 410 and a heat-conducting element 420. The circulating heat exchange tube 410 is embedded in the secondary lining 300 and extends along the secondary lining 300. The circulating heat exchange tube 410 is used to supply the circulating heat exchange medium, so that the circulating heat exchange tube 410 can exchange heat with the secondary lining 300. The heat-conducting element 420 is embedded in the secondary lining 300. One end of the heat-conducting element 420 is located between the circulating heat exchange tube 410 and the outside of the secondary lining 300 and forms thermal contact with the circulating heat exchange tube 410. The end of the heat-conducting element 420 away from the circulating heat exchange tube 410 extends towards the soil mass 100 along the thickness direction of the secondary lining 300.

[0044] The heat-conducting component 420 forms a low thermal resistance heat transfer path between the circulating heat exchange tube 410 and the outer side of the secondary lining 300, which can effectively reduce the thermal resistance of the lining concrete, allowing heat to quickly cross the main thermal resistance area in the thickness direction of the secondary concrete lining 300. The internal temperature gradient of the heat-conducting component 420 is small, and it can be used as a near-isothermal passive heat transfer channel, reducing the temperature difference between the area near the circulating heat exchange tube 410 and the area outside the secondary lining 300, improving the temperature field distribution in the secondary lining 300 and the surrounding rock outside, and significantly improving the heat exchange efficiency and overall heat exchange capacity of the energy tunnel 1000.

[0045] At least a portion of the circulating heat exchange tubes 410 extend parallel to the periphery of the secondary lining 300, so that the circulating heat exchange tubes 410 are buried parallel to the secondary lining 300 to exchange heat with the secondary lining 300, thereby improving the uniformity of heat exchange between the circulating heat exchange tubes 410 and the secondary lining 300. This adapts to the long and narrow structural characteristics of the secondary lining 300, and can be laid out simultaneously with the pouring construction of the secondary lining 300. It causes little disturbance to the original support structure of the energy tunnel 1000 and has strong construction compatibility.

[0046] Multiple heat-conducting elements 420 are provided, and the multiple heat-conducting elements 420 are arranged sequentially along the extension direction of the circulating heat exchange tube 410, so that the multiple heat-conducting elements 420 can form a continuous heat-conducting node along the heat exchange path, expand the effective heat exchange area, eliminate heat exchange blind spots, and ensure the uniformity and stability of the heat exchange process.

[0047] Therefore, in summer cooling conditions, the circulating heat exchange tube 410 absorbs heat from the secondary lining 300. The circulating heat exchange medium has a high temperature, and the heat-conducting element 420 is in thermal contact with the circulating heat exchange tube 410. Heat from the circulating heat exchange tube 410 is transferred to the heat-conducting element 420, and then released by the heat-conducting element 420 to the outside of the secondary lining 300, the initial support 200, or the soil and rock mass 100. This reduces heat accumulation at the circulating heat exchange tube 410, allowing the circulating heat exchange medium to continuously absorb heat from the inside of the secondary lining 300, thus lowering the temperature of the energy tunnel 1000. In winter heating conditions, the heat-conducting element 420 absorbs heat from the outside of the secondary lining 300, the initial support 200, or the soil and rock mass 100 and transfers it to the circulating heat exchange tube 410. The temperature of the circulating heat exchange medium rises, and the circulating heat exchange tube 410 continuously releases heat to the inside of the secondary lining 300 to increase the temperature inside the energy tunnel 1000.

[0048] Reference Figure 2 and Figure 3 In this embodiment, the circulating heat exchange tube 410 is a serpentine tube, comprising multiple first tube segments 411 extending parallel to the axial direction of the secondary lining 300 and multiple second tube segments 412 extending circumferentially along the secondary lining 300. The first tube segments 411 extend from one end of the secondary lining 300 to the other end. The second tube segments 412 are connected to the ends of two adjacent first tube segments 411, and are staggered, meaning one second tube segment 412 is connected to one end of a first tube segment 411, and the other second tube segment 412 is connected to the other end of a first tube segment 411, resulting in a reciprocating bending shape for the circulating heat exchange tube 410. Thus, the multiple first tube segments 411 are sequentially connected through the second tube segments 412, requiring only one inlet and one outlet for the circulating heat exchange tube 410, facilitating control of the flow of the circulating heat exchange medium.

[0049] In addition, in other embodiments, a plurality of first pipe segments 411 may also be arranged in an arc shape parallel to the circumference of the secondary lining 300, with the first pipe segment 411 extending from one side of the secondary lining 300 to the other side, and the second pipe segment 412 extending along the axial direction of the secondary lining 300 to connect two adjacent first pipe segments 411.

[0050] In addition, in other embodiments, the circulating heat exchange tube 410 can also be a U-shaped tube, a circumferential coil, an axial straight tube group, or a multi-loop parallel tube group. The circulating heat exchange tube 410 can be flexibly selected according to the cross-sectional dimensions of the secondary lining 300, the design heat exchange power, and the on-site construction conditions to adapt to the heat exchange requirements of the energy tunnel 1000 under different working conditions.

[0051] In this embodiment, the circulating heat exchange tubes 410 are evenly arranged on a curved surface parallel to the periphery of the secondary lining 300. The circulating heat exchange tubes 410 are reciprocated in a curved shape, so that the structural space of the secondary lining 300 can be fully utilized to arrange the heat exchange pipelines, maximize the use of the cross section of the secondary lining 300 to increase the overall heat exchange area, and at the same time make the contact interface between the circulating heat exchange tubes 410 and the lining evenly distributed, avoiding uneven temperature distribution of the secondary lining 300 caused by local concentration of the circulating heat exchange tubes 410.

[0052] In this embodiment, the material of the circulating heat exchange tube 410 can be HDPE, PE, cross-linked polyethylene, or other corrosion-resistant pipes suitable for ground source heat pump systems.

[0053] In this embodiment, the inner diameter of the circulating heat exchange tube 410 is 20.4 mm, the wall thickness is 2.3 mm, the spacing between the first tube segments 411 of adjacent circulating heat exchange tubes 410 is 0.6 m, and the length of a single first tube segment 411 is approximately 338.6 m. The circulating heat exchange medium within the circulating heat exchange tube 410 can be water, an aqueous ethylene glycol solution, antifreeze, or other heat exchange media. During summer cooling operation, the inlet temperature of the circulating heat exchange medium can be 35°C, and the flow rate can be 0.6 m / s. Furthermore, in other embodiments, the above parameters of the circulating heat exchange tube 410 can also be other suitable values.

[0054] In this embodiment, multiple heat-conducting components 420 are uniformly arrayed on the curved surface where the circulating heat exchange pipes 410 are arranged, thereby forming a uniformly distributed heat-conducting network throughout the entire curved surface of the lining. This allows for efficient and uniform heat transfer between the soil / rock mass 100 and the circulating heat exchange pipes 410, eliminating weak heat exchange areas in the secondary lining 300 and further improving overall heat exchange efficiency and uniformity. The uniform array arrangement makes the internal stress of the secondary lining 300 more balanced, reducing the negative impact of the embedded heat-conducting components 420 on the structural mechanical properties of the secondary lining 300 and ensuring the load-bearing capacity of the secondary lining 300.

[0055] Specifically, in this embodiment, multiple heat-conducting elements 420 are evenly spaced along the circumference of the secondary lining 300 to form an arc-shaped heat-conducting element group. In each heat-conducting element group, the distance between two adjacent heat-conducting elements 420 is the same as the distance between two adjacent first pipe segments 411 in the circulating heat exchange tube 410, so that each heat-conducting element 420 in the heat-conducting element group can be directly opposite the circulating heat exchange tube 410.

[0056] Multiple heat-conducting components are evenly spaced along the axial direction of the secondary lining 300, forming a grid-like heat-conducting system across the entire circumferential and axial range of the secondary lining 300, further avoiding areas with insufficient local heat exchange.

[0057] The spacing between adjacent heat-conducting component groups is 0.6m–1.8m. This spacing ensures the coverage density of the heat-conducting components 420, avoids heat exchange blind spots, controls the total amount of heat-conducting components 420, balances the improvement of heat exchange performance with material and construction costs, avoids damage to the secondary lining 300 structure due to excessively dense spacing, and prevents poor heat exchange effect due to excessively sparse spacing. It also reduces the heat exchange contribution of the heat-conducting components 420 caused by overlapping heat-affected zones, and reduces thermal interference caused by excessively dense arrangement of heat-conducting components 420.

[0058] Preferably, the spacing between the heat-conducting component groups along the axial direction of the secondary lining 300 is 0.9–1.5 m. More preferably, in a recommended engineering embodiment, the spacing between the heat-conducting component groups is 1.2 m. The radius of the heat-conducting component 420 can be 5 mm–25 mm, preferably 15 mm–20 mm, and the radius of the heat-conducting component 420 can also be adjusted according to the thickness of the secondary lining 300, the heat exchange load, and the installation space.

[0059] In this embodiment, the heat-affected radius of a single heat-conducting component 420 after 120 days of operation is 0.6m–0.8m. When the axial spacing of the heat-conducting component group is approximately 1.2m, the heat-affected zones of adjacent heat-conducting components 420 can form a more reasonable connection, which can balance the heat exchange coverage and arrangement efficiency, and reduce thermal interference caused by overly dense arrangement.

[0060] In addition, in other embodiments, for areas with strong groundwater seepage and good heat transfer capacity, the heat-conducting components 420 can be arranged sparsely; for areas with high heat load, weak thermal conductivity of soil and rock 100, or concentrated local heat exchange demand, the heat-conducting components 420 can be arranged densely.

[0061] In this embodiment, the angle between the heat-conducting element 420 and the thickness direction of the secondary lining 300 is no greater than 30°, so that the heat-conducting element 420 is basically arranged along the thickness direction of the lining. This can effectively shorten the heat conduction path inside the secondary lining 300, reduce the thermal resistance, and enhance the heat transfer efficiency of the heat-conducting element 420.

[0062] Preferably, in this embodiment, the heat-conducting element 420 extends radially along the secondary lining 300. For the arched secondary lining 300, the radially extending arrangement of the heat-conducting element 420 allows it to be laid along the shortest path of the secondary lining 300's thickness, shortening the heat conduction distance and reducing thermal resistance. The radially arranged heat-conducting element 420 aligns with the force direction of the arched secondary lining 300, minimizing structural disturbance to the secondary lining 300, reducing the likelihood of weakening its load-bearing capacity, and ensuring the mechanical safety of the energy tunnel 1000 support structure.

[0063] In addition, in other embodiments, when the secondary lining 300 is rectangular, horseshoe-shaped or other shapes, the heat-conducting element 420 extends along the thickness direction of the local secondary lining 300 in which it is located.

[0064] The length of the heat-conducting element 420 is adapted to the thickness of the secondary lining 300, specifically 0.80 to 1.05 times the thickness of the secondary lining 300. In one embodiment, the thickness of the secondary lining 300 is 0.45 m, and the length of the heat-conducting element 420 is 0.45 m.

[0065] Reference Figure 4 Specifically, in this embodiment, the length of the heat-conducting component 420 is less than the thickness of the secondary lining 300, so that the heat-conducting component 420 is embedded in the secondary lining 300. This allows the heat-conducting component 420 to be integrally cast and fixed in the secondary lining 300 during construction, eliminating the need for further construction on the initial support 200. At the same time, it prevents the heat-conducting component 420 from protruding out of the secondary lining 300, thus preventing damage to the tunnel structure such as the initial support 200 and the waterproof membrane, and ensuring the support safety and waterproof performance of the tunnel.

[0066] The distance between the end of the heat-conducting element 420 closest to the circulating heat exchange tube 410 and the outer wall of the circulating heat exchange tube 410 is 0mm-100mm. This ensures efficient heat transfer between the two, avoids excessive spacing which would increase contact thermal resistance, and guarantees efficient heat transfer to the circulating heat exchange tube 410. The distance between the end of the heat-conducting element 420 furthest from the circulating heat exchange tube 410 and the outer side of the secondary lining 300 is 0mm-100mm. This allows the heat-conducting element 420 to be as close as possible to the rock and soil mass 100, facilitating sufficient heat exchange with the rock and soil mass 100.

[0067] In addition, in other embodiments, when the heat-conducting element 420 is inclined relative to the thickness direction of the secondary lining 300, the length of the heat-conducting element 420 may be greater than the thickness of the secondary lining 300.

[0068] Reference Figure 5In this embodiment, the heat-conducting component 420 includes a phase change heat pipe, which comprises a heat pipe shell 421, a capillary wick 422, and a phase change medium. The heat pipe shell 421 forms a sealed cavity, and the phase change medium is encapsulated within the cavity of the heat pipe shell 421. The capillary wick 422 is disposed within the heat pipe shell 421 and extends along the inner wall of the cavity of the heat pipe shell 421. The inner side of the capillary wick 422 encloses and forms a vapor channel 423 extending axially along the heat pipe shell 421. By utilizing the latent heat of phase change of the phase change medium to transfer heat, the heat transfer efficiency is much higher than that of the traditional solid metal heat-conducting component 420, enabling rapid and long-distance heat transfer, significantly enhancing the heat exchange capacity between the soil / rock mass 100 and the circulating heat exchange pipe 410, and improving the heat exchange efficiency of the energy tunnel 1000.

[0069] Specifically, under summer cooling conditions, the circulating heat exchange medium enters the circulating heat exchange tube 410 at a higher temperature, and the heat is transferred to the secondary lining 300 around the circulating heat exchange tube 410. The end of the phase change heat pipe located near the circulating heat exchange tube 410 absorbs heat from the vicinity of the circulating heat exchange tube 410. The phase change medium in this end of the phase change heat pipe absorbs heat and evaporates. The resulting vapor migrates along the vapor channel 423 to the other end of the phase change heat pipe and condenses and releases heat in the end of the phase change heat pipe near the rock and soil mass 100. The condensed liquid phase change medium flows back to the end of the phase change heat pipe near the circulating heat exchange tube 410 under the action of the capillary wick 422, forming a continuous phase change heat transfer cycle. In winter heating mode, the phase change medium in the end of the phase change heat pipe near the soil 100 absorbs heat and evaporates from the soil 100. The steam formed migrates along the steam channel 423 to the other end of the phase change heat pipe and condenses and releases heat in the end of the phase change heat pipe near the circulating heat exchange tube 410. The condensed liquid phase change medium flows back to the end of the phase change heat pipe near the soil 100 under the action of the capillary 422.

[0070] Therefore, through the cooperative structure of capillary wick 422 and steam channel 423, automatic circulation of phase change medium can be achieved, and continuous and stable operation can be achieved without additional power equipment. The structure is simple, the operation is highly reliable, and it is suitable for long-term and low-maintenance use scenarios within the Energy Tunnel 1000.

[0071] In this embodiment, the heat pipe shell 421 is made of copper, stainless steel or aluminum alloy, which has excellent thermal conductivity and can further reduce the interfacial thermal resistance. In addition, the heat pipe shell 421 has strong corrosion resistance and can adapt to the complex environment of humid and corrosive media in the tunnel, thus extending the service life of the device.

[0072] The phase change medium may include one, two or more of water, ethanol and acetone. The appropriate medium can be selected for different temperature ranges to ensure that the phase change process is carried out efficiently at the target temperature and improve the environmental adaptability of the phase change heat pipe to different regions and different ground temperature conditions.

[0073] Furthermore, in other embodiments, the heat pipe housing 421 may be made of other materials. In other embodiments, the phase change medium may be other phase change materials.

[0074] In addition, in other embodiments, the phase change heat pipe may be at least one of the following: a gravity heat pipe, a two-phase closed thermosiphon, or a closed phase change heat transfer element, in addition to the capillary 422 heat pipe in this embodiment.

[0075] In other embodiments, the heat-conducting component 420 may also be a two-phase closed thermosiphon, a loop heat pipe, a heat spreader, a phase change heat-conducting rod, a metal high heat-conductivity rod, or a heat-conducting component filled with phase change material, etc., used to improve the heat transfer capacity in the 300mm thickness direction of the secondary lining.

[0076] The above are merely preferred embodiments of this utility model. Therefore, all equivalent changes or modifications made in accordance with the structure, features and principles of this utility model patent application are included within the scope of this utility model patent application.

Claims

1. A phase change enhanced heat exchange device for an energy tunnel, the energy tunnel (1000) comprising an initial support (200) disposed inside a rock and soil mass (100) and a secondary lining (300) disposed inside the initial support (200); Its features are, The phase change enhanced heat exchange device (400) includes: A circulating heat exchange tube (410) is used to supply the circulating heat exchange medium. The circulating heat exchange tube (410) is embedded in the secondary lining (300) and extends along the secondary lining (300). A heat-conducting element (420) is embedded within the secondary lining (300). One end of the heat-conducting element (420) is located between the circulating heat exchange pipe (410) and the outer side of the secondary lining (300) and forms thermal contact with the circulating heat exchange pipe (410). The end of the heat-conducting element (420) away from the circulating heat exchange pipe (410) faces the rock and soil mass (100) along the thickness direction of the secondary lining (300). The circulation heat exchange tube (410) extends parallel to the periphery of the secondary lining (300) at least in part; the distance between the end of the heat-conducting element (420) near the circulation heat exchange tube (410) and the outer wall of the circulation heat exchange tube (410) is 0mm-100mm; and the distance between the end of the heat-conducting element (420) away from the circulation heat exchange tube (410) and the outer side of the secondary lining (300) is 0mm-100mm. Multiple heat-conducting elements (420) are provided, and the multiple heat-conducting elements (420) are arranged sequentially along the extension direction of the circulating heat exchange tube (410); the angle between the heat-conducting element (420) and the thickness direction of the secondary lining (300) is not greater than 30°, the multiple heat-conducting elements (420) are arranged at uniform intervals along the circumference of the secondary lining (300) to form heat-conducting element groups, the multiple heat-conducting element groups are arranged at uniform intervals along the axial direction of the secondary lining (300), and the spacing between adjacent heat-conducting element groups is 0.6m–1.8m; The heat-conducting component (420) includes a phase change heat pipe, which includes a heat pipe shell (421), a capillary wick (422), and a phase change medium. The heat pipe shell (421) forms a sealed cavity, and the phase change medium is encapsulated in the cavity of the heat pipe shell (421). The capillary wick (422) is disposed inside the heat pipe shell (421) and extends along the inner wall of the cavity of the heat pipe shell (421). The inner side of the capillary wick (422) surrounds and forms a vapor channel (423) extending axially along the heat pipe shell (421).

2. The phase change enhanced heat exchange device for energy tunnels as described in claim 1, characterized in that, The circulating heat exchange tube (410) is any one of U-shaped tube, serpentine tube, circumferential coil, axial straight tube group or multi-loop parallel tube group.

3. The phase change enhanced heat exchange device for energy tunnels as described in claim 2, characterized in that, The circulating heat exchange tubes (410) are evenly arranged on a curved surface parallel to the periphery of the secondary lining (300).

4. The phase change enhanced heat exchange device for energy tunnels as described in claim 3, characterized in that, Multiple heat-conducting elements (420) are arranged in a uniform array on the curved surface of the circulating heat exchange tube (410).

5. A phase change enhanced heat exchange device for energy tunnels as described in claim 1, characterized in that, The heat pipe housing (421) is made of copper, stainless steel or aluminum alloy, and the phase change medium includes one, two or more of water, ethanol and acetone.

6. The phase change enhanced heat exchange device for energy tunnels as described in claim 1, characterized in that, The heat-conducting component (420) is embedded in the secondary lining (300).

7. A phase change enhanced heat exchange device for energy tunnels as described in claim 1, characterized in that, The secondary lining (300) is arched, and the heat-conducting element (420) extends radially along the secondary lining (300).

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