Terrestrial heat collecting system and construction and use method thereof

Abstract

The invention discloses a terrestrial heat collecting system and a construction and use method thereof, the terrestrial heat collecting system comprises a plurality of prefabricated terrestrial heat energy piles, an expansion cavity space is formed below each terrestrial heat energy pile, and the expansion cavity spaces are filled with circulating water for terrestrial heat exchange; a circulating water cavity is formed in the prefabricated geothermal energy pile, a heat exchange mechanism used for conducting heat exchange between the circulating water cavity and the expanded cavity space is arranged in the prefabricated geothermal energy pile, and the heat exchange mechanism comprises a heat exchange pipe located in the circulating water cavity and a heat exchange net located in the expanded cavity space. A release mechanism used for releasing the heat exchange net after construction of the energy pile is completed is arranged in the prefabricated geothermal energy pile; according to the prefabricated geothermal energy pile, the heat exchange structure is integrated into the prefabricated geothermal energy pile, and the energy pile can serve as a structural component and a heat exchange component, so that additional drilling or excavation for mounting a ground source heat pump system is not needed, and the land cost and the mounting cost are saved.

Description

Technical Field

[0001] The present invention relates to the technical field of geothermal energy collection and utilization, and particularly to a geothermal energy collection system and its construction and use methods. Background Art

[0002] Compared with fossil fuel combustion and traditional air-source heat pumps, ground-source heat pump systems can reduce carbon emissions and environmental pollution. The ground-source heat exchangers used in traditional ground-source heat pump systems are closed heat absorption pipes buried in horizontal trenches or vertical drill holes. According to the need, antifreeze in the circulating heat absorption pipes is used to transfer shallow geothermal energy from the geothermal source to the ground (in winter), or store the ground heat energy in the geothermal source (in summer). In addition to for inherent structural purposes, installing a ground-source heat pump system requires additional drilling and excavation, and the large area of additional land use and high installation costs make this technology difficult to promote and use.

[0003] Energy piles are a new application in ground-source heat pump systems, which integrate geothermal heat exchangers into the foundation structure. Compared with traditional ground-source heat pump systems, energy piles can serve both as structural members and heat exchange members, so there is no need for additional drilling or excavation for installing a ground-source heat pump system, saving land costs and installation costs.

[0004] Currently, there are mainly two types of energy piles: cast-in-place piles and precast piles. Groundwater seeping into the bottom of the piles is pumped through a water extraction pipe. However, when groundwater resources are scarce, the extracted groundwater and its heat are very limited, and geothermal resources cannot be obtained through groundwater, and effective collection and utilization of geothermal energy cannot be achieved. Summary of the Invention

[0005] Technical Objective: Aiming at the deficiencies of existing geothermal energy collection methods, the present invention discloses a geothermal energy collection system and its construction and use methods.

[0006] Technical Solution: To achieve the above technical objective, the present invention adopts the following technical solution: A geothermal energy collection system includes a number of precast geothermal energy piles. An enlarged cavity space is opened below each geothermal energy pile, and the enlarged cavity space is filled with circulating water for geothermal heat exchange; a circulating water cavity is arranged inside the precast geothermal energy pile, and a heat exchange mechanism for heat exchange between the circulating water cavity and the enlarged cavity space is arranged inside the precast geothermal energy pile. The circulating water introduced into the circulating water cavity enters the enlarged cavity space for geothermal heat exchange; the heat exchange mechanism includes heat exchange pipes in the circulating water cavity and a heat exchange network in the enlarged cavity space. The injection and extraction of the circulating water in the enlarged cavity space are carried out through the heat exchange pipes to form a cycle for geothermal utilization, and a release mechanism for releasing the heat exchange network after the construction of the energy pile is completed is arranged inside the precast geothermal energy pile.

[0007] Preferably, the release mechanism of the present invention includes a heat exchange network storage cavity, in which a release piston is arranged, the release piston is slidably connected to the heat exchange network storage cavity, the cavity where the release piston is located on the side facing away from the heat exchange network is connected to the heat exchange tube, and the heat exchange network is released by injecting water into the heat exchange tube to push the release piston to move.

[0008] Preferably, the heat exchange mesh of the present invention is formed into a mesh bag by weaving copper wire, one end of the mesh bag is fixedly connected to the end of the release piston, and the other end is a free end that is pushed out of the heat exchange mesh storage cavity into the expansion cavity space for release, the inner and outer surfaces of the heat exchange mesh are sprayed with water-soluble polymers, and the release piston and the heat exchange mesh storage cavity are used to form a connecting mechanism for connecting the heat exchange mesh with the heat exchange mesh storage cavity after the release piston pushes the heat exchange mesh to release, so that water enters the heat exchange mesh to expand the heat exchange mesh.

[0009] Preferably, the release piston of the present invention adopts an I-shaped structure, and both ends of the release piston slide in cooperation with the storage chamber of the heat exchange network. The connecting mechanism includes a water groove opened on the inner wall of the storage chamber of the heat exchange network and located on the sliding path of the release piston, and a connecting hole opened at the connecting end of the release piston and the heat exchange network. After the end of the release piston moves to the water groove position, water flows from the water groove to the inside of the heat exchange network.

[0010] Preferably, after the construction of the prefabricated geothermal energy pile of the present invention is completed, water is filled into the storage chamber of the heat exchange network through the heat exchange pipe, and the release piston is pushed under the action of water pressure to push the heat exchange network out of the storage chamber of the heat exchange network. After the end of the release piston moves to the water flow groove, the release piston stops moving, and water flows from the water flow groove to the connecting hole at the end of the release piston and enters the heat exchange network. The water-soluble polymers in the inner and outer layers of the heat exchange network prevent water from flowing out of the heat exchange network, and the water flow stretches the heat exchange network to expand it.

[0011] Preferably, the present invention provides a flow cavity for allowing water in the heat exchange tube to flow directly into the expanded cavity space below the storage cavity of the heat exchange network along the height direction of the prefabricated geothermal energy pile, the flow cavity is connected to the end of the heat exchange tube, and a water-soluble polymer one-way valve core is provided at the outlet of the flow cavity, and the water-soluble polymer one-way valve core limits the outflow of water from the flow cavity before dissolving.

[0012] Preferably, a central hole for the drilling end of a drilling device to enter and exit is concentrically arranged in the prefabricated geothermal energy pile of the present invention, the drilling equipment includes a core drill tube, a drill rod is symmetrically hinged at the end of the core drill tube, an alloy cutter head is arranged at the end of the drill rod, and a retracting mechanism for adjusting the angle of the drill rod relative to the core drill tube and changing the drilling radius is arranged in the core drill tube.

[0013] Preferably, the retracting and extending mechanism of the present invention includes an intermediate ejector rod coaxially arranged with the core drill pipe and a support rod whose end is rotatably matched with the intermediate ejector rod. The other end of the support rod is hinged to the drill rod. By adjusting the axial position of the intermediate ejector rod relative to the core drill pipe, the support rod is driven to move to adjust the position of the drill rod, thereby adjusting the drilling range.

[0014] The present invention discloses a construction method based on the above geothermal collection system. A drilling device is used to drill a hole below the prefabricated geothermal energy pile. The prefabricated geothermal energy pile is pressed down by a precast pile static press and moves down along the drilling path of the drilling device for construction and installation. After reaching the installation depth, the drilling device changes the drilling radius to process an enlarged cavity space for accommodating groundwater below the prefabricated geothermal energy pile. Then, the drilling device is removed from the prefabricated geothermal energy pile. Finally, water is filled into the heat exchange pipe of the prefabricated geothermal energy pile, and the heat exchange network is released and expanded, and the enlarged cavity space is filled with water, so that the heat exchange network is distributed in the enlarged cavity space to contact and exchange heat with the circulating water.

[0015] Preferably, after the construction of the prefabricated geothermal energy pile of the present invention is completed, the heat exchange network absorbs geothermal energy from the circulating water in the enlarged cavity space and conducts it to the prefabricated geothermal energy pile through the heat exchange pipe. At the same time, the circulating water in the enlarged cavity space synchronously absorbs geothermal energy, and the geothermal energy is conducted to the ground through the heat exchange pipe itself and the heat-exchanged circulating water absorbed by the heat exchange pipe.

[0016] Beneficial effects: A geothermal collection system and its construction and use method disclosed by the present invention have the following beneficial effects: 1. The present invention uses a heat exchange network that can be released after the construction of the prefabricated geothermal energy pile to exchange heat with the circulating water in the enlarged cavity space, which can effectively increase the heat exchange contact area and thus improve the geothermal collection efficiency.

[0017] 2. The heat exchange network of the present invention is formed by weaving copper wires into a net bag structure, and is combined with a water-soluble polymer brush-coated on the inner and outer surfaces of the net bag, which can make the net bag in a contracted state before release, facilitating construction and installation. At the same time, after the construction is completed, the water flowing into the net bag is used to assist in expanding the heat exchange network, so that it can be unfolded in the enlarged cavity space, thereby improving the subsequent heat exchange and heat transfer effects.

[0018] 3. Through the structural design of the release piston and the heat exchange network storage cavity of the present invention, after the release piston slides to the release position, the heat exchange network release can be automatically switched, thereby ensuring the operation reliability of the heat exchange network release and unfolding in a closed underground space, reducing the construction control difficulty, and realizing the switching based on the mechanical structure design without complex electric control or pneumatic facilities, which can simplify the internal structure of the prefabricated geothermal energy pile, facilitate processing and manufacturing, and at the same time reduce the construction difficulty.

[0019] 4. The present invention provides a flow cavity below the heat exchange network storage cavity. The water-soluble polymer one-way valve core in the flow cavity can restrict water from directly flowing out of the heat exchange tube, so that water can enter the cavity through the connection between the heat exchange tube and the heat exchange network storage cavity, providing water pressure to push the release piston to move, and entering the heat exchange network to use the water pressure to expand the heat exchange network.

[0020] 5. The present invention provides a retractable drilling device that enters and exits through the central hole of the prefabricated geothermal energy pile. During the drilling process, the prefabricated geothermal energy pile is pressed in synchronously. After the installation of the energy pile is completed, an enlarged cavity space is formed corresponding to the drilling device below each prefabricated geothermal energy pile to form a geothermal collection area, and the circulated water filled is used for geothermal collection and utilization. In areas rich in geothermal resources but lacking groundwater, geothermal energy can still be effectively collected and utilized without being affected by the geological environment.

[0021] 6. The retracting and extending mechanism of the present invention drives the support rod to move through the middle ejector rod, thereby changing the angles of the two drill rods hinged to the core drill rod, and further changing the drilling range of the drill rods, so that the size of the drilling hole can be adjusted flexibly to meet the drilling requirements at different stages of the construction process of the prefabricated geothermal energy pile. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0023] Figure 1 It is a schematic structural diagram of the prefabricated geothermal energy pile of the present invention; Figure 2 It is for the present invention along Figure 1 Partial enlarged view of area A; Figure 3 It is for the present invention along Figure 1 Sectional view taken along B-B; Figure 4 It is a released state diagram of the heat exchange network of the present invention; Wherein, 1 - prefabricated geothermal energy pile, 2 - enlarged cavity space, 3 - circulating water cavity, 4 - heat exchange tube, 5 - heat exchange network, 6 - heat exchange network storage cavity, 7 - release piston, 8 - overflow tank, 9 - communication hole, 10 - flow cavity, 11 - water-soluble polymer one-way valve core, 12 - core drill pipe, 13 - drill rod, 14 - alloy cutter head, 15 - middle ejector rod, 16 - support rod, 17 - end head plate, 18 - sealing plate, 19 - sewage pipe, 20 - high-pressure water gun barrel. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Reference will now be made in detail to the embodiments of the present disclosure, one or more examples of which are set forth below. Each embodiment and example is provided by way of explanation of the apparatus, composition, and materials of the present disclosure, and not by way of limitation. On the contrary, the following description provides a convenient illustration for implementing the exemplary embodiments of the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the teachings of the present disclosure without departing from the scope or spirit of the present disclosure.

[0025] As Figures 1-4 shown, the present invention discloses a geothermal collection system, including a plurality of prefabricated geothermal energy piles 1. An enlarged cavity space 2 is formed below each geothermal energy pile 1, and circulating water is filled in the enlarged cavity space 1 for geothermal heat exchange; a circulating water cavity 3 is arranged inside the prefabricated geothermal energy pile 1, and a heat exchange mechanism for heat exchange between the circulating water cavity 3 and the enlarged cavity space 2 is arranged in the prefabricated geothermal energy pile 1. The circulating water introduced into the circulating water cavity 3 enters the enlarged cavity space 2 for geothermal heat exchange, and the prefabricated geothermal energy pile 1 is used for geothermal collection in the corresponding area. The collection method is circulating water heat exchange, so that the circulating water can be led out for direct utilization of geothermal energy; the heat exchange mechanism includes heat exchange tubes 4 arranged in the circulating water cavity 3 and a heat exchange net 5 located in the enlarged cavity space 2, and a release mechanism for releasing the heat exchange net 5 after the construction of the energy pile is completed is arranged in the prefabricated geothermal energy pile 1.

[0026] Since only heat is absorbed from the groundwater by the circulating water, inside the prefabricated geothermal energy pile 1, the contact area between the heat conduction tube and the groundwater with geothermal energy is limited, and only relying on the natural heat transfer of the energy pile, heat exchange cannot be carried out quickly. Therefore, in the present invention, the heat exchange net 5 is provided to absorb the heat in the groundwater so as to be able to quickly conduct heat exchange through the heat exchange tubes to the ground heat exchanger. The heat exchange net 5 and the heat exchange tubes 4 are both made of metal materials with good thermal conductivity, preferably copper. The number of heat exchange tubes 4 is four groups, which are evenly distributed along the circumferential direction of the prefabricated geothermal energy pile 1. Correspondingly, the number of the heat exchange nets 5 can correspond to that of the heat exchange tubes 4. Since the heat exchange net 5 is made of metal material, it cannot automatically expand after being released. Therefore, a structure capable of assisting in expansion needs to be correspondingly arranged. Figure 1 The right heat exchange net 5 on the right is in an expanded state and can be distributed in the enlarged cavity space 2 to exchange heat with the internal groundwater.

[0027] As Figure 2As shown, in an embodiment of the present invention, the release mechanism includes a heat exchange network storage cavity 6. A release piston 7 is arranged in the heat exchange network storage cavity 6. The release piston 7 is slidably connected to the heat exchange network storage cavity 6. The cavity on the side of the release piston 7 facing away from the heat exchange network 5 is communicated with the heat exchange tube 4. The heat exchange network 5 is released by injecting water through the heat exchange tube 4 to push the release piston 7 to move. The continuously input water flow through the heat exchange tube 4 generates water pressure to push the release piston 7 to move. The heat exchange network 5 of the present invention is formed into a mesh bag by copper wire weaving. One end of the mesh bag is fixedly connected to the end of the release piston 7, and the other end is a free end and is pushed out of the heat exchange network storage cavity 6 into the expansion cavity space 2 for release. The inner and outer surfaces of the heat exchange network 5 are sprayed with a water-soluble polymer. A communication mechanism is provided between the release piston 7 and the heat exchange network storage cavity 6 to communicate the heat exchange network 5 with the heat exchange network storage cavity 6 after the release piston 7 pushes the heat exchange network 5 for release, so that water enters the heat exchange network 5 for heat exchange network expansion. To prevent the premature dissolution of the water-soluble polymer and affect the opening of the heat exchange network, the present invention also sets a rubber plug at the outlet of the heat exchange network storage cavity 6 to prevent water from entering and contacting the water-soluble polymer on the surface of the heat exchange network before release.

[0028] As Figure 2 and Figure 4 shown, the release piston 7 of the present invention adopts an I-shaped structure. The two ends of the release piston 7 are slidably matched with the heat exchange network storage cavity 6. The communication mechanism includes a water passing groove 8 opened on the inner wall of the heat exchange network storage cavity and located on the sliding path of the release piston 7 and a communication hole 9 opened at the connection end of the release piston 7 and the heat exchange network 5. After the end of the release piston 7 moves to the position of the water passing groove 8, the water flow flows from the water passing groove 8 into the inside of the heat exchange network 5. In addition to serving as a channel for water flow, the water passing groove 8 can also control the sliding distance of the release piston 7 through the opening position to control the release position of the heat exchange network. A push rod for pushing open the rubber plug can also be arranged at one end of the release piston 7 close to the rubber plug. The push rod moves synchronously with the release piston 7 to prevent the rubber plug 7 from hindering the release of the heat exchange network 5; Figure 2 In [description], the heat exchange network 5 is in an unreleased state and is located in the heat exchange network storage cavity 6, Figure 4 In [description], the heat exchange network 5 is in a released state. At this time, the release piston moves to the water passing groove 8, and the communication hole 9 and the water passing groove 8 form a passage.

[0029] After the construction of the prefabricated geothermal energy pile 1 of the present invention is completed, water is filled into the heat exchange network storage chamber 6 through the heat exchange pipe 4, and the release piston 7 is pushed under the action of water pressure to push the heat exchange network 5 out of the heat exchange network storage chamber 6. After the end of the release piston 7 moves to the water flow groove 9, the release piston 7 stops moving, and water flows from the water flow groove 8 to the connecting hole 9 at the end of the release piston 7 and enters the heat exchange network 5. The water-soluble polymers in the inner and outer layers of the heat exchange network 5 prevent water from flowing out of the heat exchange network 5. Under the action of water pressure, the heat exchange network can be expanded in a short time, so that the heat exchange network 5 can be filled into the expanded cavity space, and the water-soluble polymer will continue to dissolve, so that the water flow can flow normally through the mesh of the heat exchange network 5.

[0030] The present invention also provides a flow cavity 10 for allowing the water in the heat exchange tube 4 to flow directly into the expansion cavity space 2 below the heat exchange network storage cavity 6 along the height direction of the prefabricated geothermal energy pile. The flow cavity 10 is connected to the end of the heat exchange tube 4. A water-soluble polymer one-way valve core 11 is provided at the outlet of the flow cavity 10. The water-soluble polymer one-way valve core 11 limits the water from flowing out of the flow cavity 10 before dissolving. In the initial stage, the water cannot flow out of the flow cavity 10 and will enter the heat exchange network storage cavity 6 above through the heat exchange tube 4, generating water pressure to release and expand the heat exchange network. At this time, the release piston 7 and other structures will still release the water. The flow produces a certain resistance, resulting in an inability to flow quickly; after the water-soluble polymer one-way valve core 11 dissolves, the water flows directly out of the flow cavity 10, where the resistance is small, and rapid water injection can be achieved, so that the water fills the expanded cavity space 2, so as to improve the overall construction efficiency and shorten the time; the flow cavity 10 is formed by a head plate 17 and a sealing plate 18 of the L pile arranged at the end of the prefabricated geothermal energy pile 1, and the outlet of the flow cavity 10 is along the radial direction of the prefabricated geothermal energy pile 1. Impurities in the expanded cavity space can be cleaned by water injection, and sewage can be discharged in conjunction with a sewage pipe 19 arranged in the prefabricated geothermal energy pile 1.

[0031] In order to facilitate the opening of the expanded cavity space 2 and to be able to simultaneously install the prefabricated geothermal energy pile 1, a central hole for the drilling end of the drilling equipment to enter and exit is concentrically arranged in the prefabricated geothermal energy pile 1 of the present invention. The drilling equipment includes a core drill tube 12, and a drill rod 13 is symmetrically hinged at the end of the core drill tube 12. An alloy cutter head 14 is arranged at the end of the drill rod 13. A retractable mechanism for adjusting the angle of the drill rod 13 relative to the core drill tube 12 to change the drilling radius is arranged in the core drill tube 12; a sewage pipe 19 is penetrated in the core drill tube 12, and at the same time, a high-pressure water gun tube 20 is arranged in the core drill tube 12 directly to the alloy cutter head 14. When cutting hard rock, on the one hand, the cutter head is cooled by water from the high-pressure water gun, and on the other hand, it plays the role of high-pressure water jet cutting to assist in drilling.

[0032] The retracting and extending mechanism of the present invention includes an intermediate ejector rod 15 coaxially arranged with the core drill pipe 12 and a support rod 16 whose end is rotatably fitted with the intermediate ejector rod 15. The other end of the support rod 16 is hinged to the drill rod 13. By adjusting the axial position of the intermediate ejector rod 15 relative to the core drill pipe 12, the support rod 16 is driven to move to adjust the position of the drill rod 13 for drilling range adjustment. After drilling is completed, the two drill rods 13 can be retracted to the vertical position so that they can be removed from the prefabricated geothermal energy pile 1 together with the core drill pipe 12, which can not only ensure the synchronism of the drilling and pile pressing processes and improve the construction operation efficiency, but also ensure that the enlarged cavity space 2 generated by drilling can maintain the position corresponding to the prefabricated geothermal energy pile 1, realizing the effective collection and utilization of geothermal energy at each distribution position in the geothermal area.

[0033] The present invention also discloses a construction method based on the above geothermal collection system. A drilling device is used to drill a hole under the prefabricated geothermal energy pile. The prefabricated geothermal energy pile is pressed down by a precast pile static press and moves down along the drilling path of the drilling device for construction and installation. After reaching the installation depth, the drilling device changes the drilling radius to process an enlarged cavity space for accommodating groundwater under the prefabricated geothermal energy pile. Then, the drilling device is removed from the prefabricated geothermal energy pile. Finally, water is filled into the heat exchange pipe of the prefabricated geothermal energy pile, and the heat exchange network is released and expanded and the enlarged cavity space is filled with water, so that the heat exchange network is distributed in the enlarged cavity space to contact and exchange heat with groundwater.

[0034] During pile pressing, while the drilling device rotates slowly to drill a hole, at intervals of about 2 - 3 meters, the precast pile static press then statically presses the prefabricated geothermal energy pile by about 2 - 3 meters until the designed pile bottom elevation position. Pressure is applied to the intermediate ejector rod in the drill bit mechanism and the rotation speed of the core drill pipe is increased. Due to the support of the bottom intermediate ejector rod 15, the retracting and extending mechanism is forced to open, and the drill rod 13 will also naturally expand under the action of centrifugal force. Thus, under the simultaneous cutting of the alloy cutter head and the high-pressure water knife, the bottom enlarged cavity space is formed. After drilling is completed, the core drill pipe is directly used as a sewage pipe, and a water pump is used to pump all the sundries and sewage in the enlarged cavity space to the ground, reducing the impact on the use of heat exchange equipment in the later stage. And the enlarged cavity space can be injected with water through a high-pressure water gun barrel for cyclic flushing to make the sewage discharge more thorough, and then the drilling device is lifted out of the ground.

[0035] The present invention discloses a method of using the above-mentioned geothermal collection system. After the construction of the prefabricated geothermal energy pile is completed, the heat exchange network absorbs geothermal heat from the circulating water in the enlarged cavity space, conducts it to the prefabricated geothermal energy pile through the heat exchange pipe for geothermal conduction, and at the same time sucks the circulating water from the enlarged cavity space through the heat exchange pipe to conduct the geothermal heat to the ground. For the situation of lack of groundwater, the present invention can supplement water by injecting water into the enlarged cavity space through the heat exchange pipe, solving the problems of insufficient underground water resources and ineffective utilization of geothermal heat. It also solves the problem of difficult pile driving construction in hard rock formations. The geothermal collection system of the present invention integrates the heat exchange structure into the prefabricated geothermal energy 1. The energy pile can serve both as a structural member and a heat exchange member. Therefore, there is no need for additional drilling or excavation for installing the ground source heat pump system, saving land costs and installation costs. The geothermal heat exchange of the circulating water and the heat conduction of components such as the heat exchange network are carried out simultaneously, which can improve the efficiency of geothermal collection and utilization.

[0036] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A geothermal collection system, characterized in that, It includes a number of prefabricated geothermal energy piles (1). An enlarged cavity space (2) is opened below each geothermal energy pile (1), and circulating water is filled in the enlarged cavity space (1) for geothermal heat exchange; a circulating water cavity (3) is arranged inside the prefabricated geothermal energy pile (1), and a heat exchange mechanism for heat exchange between the circulating water cavity (3) and the enlarged cavity space (2) is arranged in the prefabricated geothermal energy pile (1). The circulating water introduced into the circulating water cavity (3) enters the enlarged cavity space (2) for geothermal heat exchange; the heat exchange mechanism includes a heat exchange tube (4) in the circulating water cavity (3) and a heat exchange net (5) in the enlarged cavity space (2). The injection and extraction of the circulating water in the enlarged cavity space (2) are carried out through the heat exchange tube (4) to form a cycle of geothermal utilization. A release mechanism for releasing the heat exchange net (5) after the construction of the energy pile is completed is arranged in the prefabricated geothermal energy pile (1).

2. The geothermal energy collection system according to claim 1, characterized in that The release mechanism includes a heat exchange net storage cavity (6), and a release piston (7) is arranged in the heat exchange net storage cavity (6). The release piston (7) is slidably connected with the heat exchange net storage cavity (6). The cavity where the side of the release piston (7) facing away from the heat exchange net (5) is located is communicated with the heat exchange tube (4). The heat exchange net (5) is released by injecting water through the heat exchange tube (4) to push the release piston (7) to move.

3. A geothermal collection system according to claim 2, characterized in that, The heat exchange net (5) is formed into a net bag by copper wire weaving. One end of the net bag is fixedly connected with the end of the release piston (7), and the other end is a free end that is pushed out of the heat exchange net storage cavity (6) and enters the enlarged cavity space (2) for release. Water-soluble polymers are sprayed on the inner and outer surfaces of the heat exchange net (5). A connecting mechanism is arranged between the release piston (7) and the heat exchange net storage cavity (6) to communicate the heat exchange net (5) with the heat exchange net storage cavity (6) after the release piston (7) pushes the heat exchange net (5) for release, so that water enters the heat exchange net (5) for heat exchange net expansion.

4. A geothermal collection system according to claim 3, characterized in that, The release piston (7) adopts an I-shaped structure. The two ends of the release piston (7) are slidably matched with the heat exchange net storage cavity (6). The connecting mechanism includes a water passing groove (8) opened on the inner wall of the heat exchange net storage cavity and located on the sliding path of the release piston (7) and a communication hole (9) opened at the connection end of the release piston (7) and the heat exchange net (5). After the end of the release piston (7) moves to the position of the water passing groove (8), water flows from the water passing groove (8) into the inside of the heat exchange net (5).

5. A geothermal collection system according to claim 4, wherein, After the construction of the prefabricated geothermal energy pile (1) is completed, water is filled into the heat exchange net storage cavity (6) through the heat exchange tube (4). Under the action of water pressure, the release piston (7) is pushed to push the heat exchange net (5) out of the heat exchange net storage cavity (6). After the end of the release piston (7) moves to the water passing groove (9), the release piston (7) stops moving. The circulating water flows from the water passing groove (8) to the communication hole (9) at the end of the release piston (7) and enters the heat exchange net (5). The water-soluble polymers on the inner and outer layers of the heat exchange net (5) prevent water from flowing out of the heat exchange net (5), and the heat exchange net (5) is expanded by the water flow.

6. The geothermal collection system according to claim 2, wherein A flow cavity (10) for directly flowing the water in the heat exchange tube (4) into the enlarged cavity space (2) is arranged below the heat exchange network storage cavity (6) along the height direction of the prefabricated geothermal energy pile. The flow cavity (10) is communicated with the end of the heat exchange tube (4). A water-soluble polymer one-way valve core (11) is arranged at the outlet of the flow cavity (10), and the water-soluble polymer one-way valve core (11) restricts the water from flowing out of the flow cavity (10) before dissolution.

7. A geothermal collection system according to claim 1, characterized in that, A central hole for the drilling end of the drilling equipment to enter and exit is concentrically arranged in the prefabricated geothermal energy pile (1). The drilling equipment includes a core drill pipe (12). Drill rods (13) are symmetrically hinged at the end of the core drill pipe (12). Alloy cutter heads (14) are arranged at the ends of the drill rods (13). A retracting and releasing mechanism for adjusting the angle of the drill rods (13) relative to the core drill pipe (12) to change the drilling radius is arranged in the core drill pipe (12).

8. A geothermal collection system according to claim 7, wherein, The retracting and releasing mechanism includes an intermediate ejector rod (15) coaxially arranged with the core drill pipe (12) and a support rod (16) whose end is rotationally matched with the intermediate ejector rod (15). The other end of the support rod (16) is hinged with the drill rod (13). By adjusting the axial position of the intermediate ejector rod (15) relative to the core drill pipe (12), the support rod (16) is driven to move to adjust the position of the drill rod (13) for drilling range adjustment.

9. A construction method of a geothermal collection system according to any one of claims 1-8, characterized in that, The drilling equipment is used to drill a hole below the prefabricated geothermal energy pile. The prefabricated geothermal energy pile is pressed down by a prefabricated pile static press and moves down along the drilling path of the drilling equipment for construction and installation. After reaching the installation depth, the drilling equipment changes the drilling radius, and an enlarged cavity space for accommodating groundwater is processed below the prefabricated geothermal energy pile. Then the drilling equipment is taken out of the prefabricated geothermal energy pile. Finally, water is filled into the heat exchange tubes of the prefabricated geothermal energy pile, and the heat exchange network is released and expanded and the enlarged cavity space is filled with water, so that the heat exchange network is distributed in the enlarged cavity space to contact and exchange heat with the circulating water.

10. The method of using a geothermal collection system according to claim 9, characterized in that, After the construction of the prefabricated geothermal energy pile is completed, the heat exchange network absorbs geothermal heat from the circulating water in the enlarged cavity space and conducts it to the prefabricated geothermal energy pile through the heat exchange tubes. At the same time, the circulating water in the enlarged cavity space synchronously absorbs geothermal heat, and the geothermal heat is conducted to the ground through the heat exchange tubes themselves and the heat-exchanged circulating water absorbed by the heat exchange tubes.

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