Coaxial geothermal heat exchanger and its installation method

Abstract

This invention relates to the field of heat exchanger technology and discloses a coaxial geothermal heat exchanger and its installation method. The coaxial geothermal heat exchanger includes an inner tube and an outer tube, with the outer tube sleeved outside the inner tube. A drilled section is provided at the bottom of the outer tube, used to drill an installation hole in the ground. The installation hole accommodates the outer tube, forming a flow space between the outer tube and the inner tube. A flow gap is formed between the bottom surface of the inner tube and the drilled section, allowing the inner tube to connect with the flow space. By utilizing the drilled section at the bottom of the outer tube to drill an installation hole in the ground, and using the drilled section and the outer tube body instead of traditional drill bits and drill rods, the outer tube is directly installed during the drilling process. Drilling and installation are completed in a single operation, eliminating cementing and well completion steps, simplifying the construction process of the coaxial geothermal heat exchanger, reducing construction difficulty, effectively lowering construction costs, and shortening the construction cycle, which is beneficial for the promotion and application of coaxial geothermal heat exchangers.

Description

Technical Field

[0001] This application relates to the field of heat exchanger technology, and in particular to a coaxial geothermal heat exchanger and a method for installing a coaxial geothermal heat exchanger. Background Technology

[0002] Geothermal energy, as a pollution-free and renewable clean energy source, boasts advantages such as vast reserves, renewability, low carbon footprint, environmental friendliness, and on-site availability, aligning with national energy conservation and emission reduction policies. Utilizing geothermal energy for building heating is a clean energy heating method. Closed-loop heat extraction technology, which typically uses coaxial sleeves as heat exchangers, allows the heat exchange fluid to circulate within the well and extract geothermal energy. This method is not limited by groundwater sources, has low construction risk, and a high success rate, and has gradually gained acceptance in recent years.

[0003] In related technologies, the construction of coaxial geothermal heat exchangers requires drilling deep holes in the ground, followed by well cementing, well completion, and heat exchanger installation. This cumbersome process results in high construction costs and a long construction period. Furthermore, because the heat exchange medium in a coaxial geothermal heat exchanger does not directly contact the soil layer but only indirectly extracts geothermal energy through heat exchange with the well wall at the bottom of the well, the heat exchange efficiency is low. Therefore, a large number of coaxial heat exchangers are required for building heating, further increasing construction difficulty and extending the construction period, severely limiting the promotion and application of coaxial geothermal heat exchangers. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art or related technologies.

[0005] In view of the above, the first aspect of the present application provides a coaxial geothermal heat exchanger, which includes an inner tube and an outer tube. The outer tube is sleeved on the outside of the inner tube. The bottom end of the outer tube is provided with a drilled part for drilling an installation hole in the ground. The installation hole is used to accommodate the outer tube. A flow space is formed between the outer tube and the inner tube. A flow gap is formed between the bottom surface of the inner tube and the drilled part, so that the inner tube is connected to the flow space.

[0006] In some technical solutions provided in this application, the outer tube includes: a first pipe fitting and a second pipe fitting, a drilled part is provided at the bottom end of the first pipe fitting, a first connecting part is provided at the top end of the first pipe fitting and the top end of the second pipe fitting, and a second connecting part is provided at the bottom end of the second pipe fitting. The second connecting part is connected to the first connecting part so that the first pipe fitting and the second pipe fitting are coaxially connected.

[0007] In some of the technical solutions provided in this application, a first sealing part is provided below the first connecting part, a second sealing part is provided below the second connecting part, and the outer tube further includes a sealing element. When the first connecting part and the second connecting part are connected, the sealing element is located between the first sealing part and the second sealing part.

[0008] In some of the technical solutions provided in this application, the drilled part is a cone, and the maximum outer diameter of the drilled part is greater than the outer wall diameter of the outer tube.

[0009] In some of the technical solutions provided in this application, the top surface of the inner pipe is 10cm to 30cm higher than the top surface of the outer pipe. And / or the heating pipeline is used to supply liquid medium to the inner pipe, the liquid medium is heated at the bottom of the outer pipe to form a high-temperature medium, and the flow distance is related to the heat exchange power, the initial temperature of the liquid medium, the high temperature of the liquid medium, and the temperature of the soil layer at the bottom of the outer pipe.

[0010] The second aspect of this application provides a method for installing a coaxial geothermal heat exchanger. This method, using a driver and an operating device, is for installing the coaxial geothermal heat exchanger as provided in the first aspect. The method includes: controlling the driver to rotate the outer tube using drilling parameters; controlling the driver to drill a mounting hole in the ground at the bottom of the outer tube, so that at least a portion of the outer tube is located within the mounting hole; controlling the driver to stop rotating when the outer tube reaches a target depth; controlling the operating device to place the inner tube inside the outer tube, creating a flow space between the inner and outer tubes, a flow gap between the bottom surface of the inner tube and the drilling portion, and connecting the inner side of the inner tube to the flow space; and controlling the operating device to connect the outer and inner tubes to a heating pipeline.

[0011] In some technical solutions provided in this application, the outer pipe includes a first pipe fitting and a second pipe fitting. The step of controlling the driver to drive the outer pipe to rotate specifically includes: controlling the driver to drive the first pipe fitting to rotate with drilling parameters; when the height of the first pipe fitting protruding from the ground reaches the target height, controlling the driver to stop rotating; controlling the operating device to connect the second pipe fitting to the top of the first pipe fitting; and controlling the driver to drive the second pipe fitting to rotate.

[0012] In some technical solutions provided in this application, the drilling parameters include: target rotation speed and target downward pressure. The step of controlling the driver to drive the outer tube to rotate according to the drilling parameters specifically includes: determining the target rotation speed and target downward pressure of the driver based on the maximum outer diameter of the borehole and the target drilling depth of the borehole; and controlling the driver to drive the outer tube to rotate according to the target rotation speed and target downward pressure.

[0013] In some of the technical solutions provided in this application, the step of controlling the actuator to drive the drilling part at the bottom of the outer tube to drill an installation hole in the ground specifically includes: calculating the difference between the radius of the installation hole and the radius of the outer tube based on the maximum outer diameter of the drilling part and the outer diameter of the outer tube; and controlling the operating device to maintain a preset distance between the outer tube and the rock wall according to the difference.

[0014] In some technical solutions provided in this application, the heating pipeline is used to supply a liquid medium to the inner pipe, and the liquid medium is heated at the bottom of the outer pipe to form a high-temperature medium. The step of controlling the operating device to place the inner pipe inside the outer pipe specifically includes: controlling the operating device to operate the inner pipe so that the top surface of the inner pipe is 10cm to 30cm higher than the top surface of the outer pipe; calculating the flow gap based on the heat exchange power, the initial temperature of the liquid medium, the high temperature of the liquid medium, and the temperature of the soil layer at the bottom of the outer pipe; and controlling the installation height of the inner pipe according to the flow gap.

[0015] Compared with related technologies, the present invention has at least the following beneficial effects:

[0016] By drilling an installation hole in the ground using the borehole section at the bottom of the outer tube, and replacing the traditional drill bit and drill rod with the borehole section and the outer tube body, the outer tube can be directly installed during the drilling process. The drilling and installation steps are completed in one operation, eliminating steps such as cementing and well completion. This simplifies the construction steps of the coaxial geothermal heat exchanger, reduces construction difficulty, effectively lowers construction costs, and shortens the construction cycle, which is conducive to the promotion and application of coaxial geothermal heat exchangers. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of some embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0018] Figure 1 A cross-sectional view of a coaxial geothermal heat exchanger according to an embodiment of this application;

[0019] Figure 2 A cross-sectional view of the outer tube of one embodiment provided in this application;

[0020] Figure 3 It shows Figure 1 Enlarged view of the circled area at point A in the middle;

[0021] Figure 4 It shows Figure 1 Enlarged view of the circled area at point B;

[0022] Figure 5 It shows Figure 2 Enlarged view of the circled area at point C;

[0023] Figure 6 A schematic diagram of the structure of a first pipe fitting according to an embodiment of this application;

[0024] Figure 7 A cross-sectional view of a first pipe fitting provided in one embodiment of this application;

[0025] Figure 8 A schematic diagram of the structure of a second pipe fitting according to an embodiment of this application;

[0026] Figure 9 A cross-sectional view of a second pipe fitting according to an embodiment of this application;

[0027] Figure 10 An installation diagram of the first pipe fitting according to one embodiment of this application;

[0028] Figure 11 An installation diagram of the second pipe fitting according to one embodiment of this application;

[0029] Figure 12 A schematic diagram of the installation of the outer tube according to one embodiment of this application;

[0030] Figure 13 A schematic diagram of the installation of the inner tube according to one embodiment of this application;

[0031] Figure 14 This is a schematic flowchart illustrating the installation method of a coaxial geothermal heat exchanger according to an embodiment of this application.

[0032] in, Figures 1 to 13 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0033] 10 Coaxial geothermal heat exchanger, 100 Inner tube, 200 Outer tube, 210 First fitting, 211 First connection, 212 First sealing part, 213 Drilled part, 220 Second fitting, 221 Second connection, 222 Second sealing part, 230 Seal, 300 Flow space, 20 Heating pipeline, 21 Water pump, 22 Heat pump, 23 Target object, 30 Mounting hole, 40 Driver. Detailed Implementation

[0034] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0035] The first aspect of this application provides a coaxial geothermal heat exchanger 10, such as... Figure 1 , Figure 3 , Figure 4 , Figure 12 and Figure 13As shown, the coaxial geothermal heat exchanger 10 includes an inner tube 100 and an outer tube 200. The outer tube 200 is sleeved on the outside of the inner tube 100. The bottom end of the outer tube 200 is provided with a drilled part 213, which is used to drill an installation hole 30 in the ground. The installation hole 30 is used to accommodate the outer tube 200. A flow space 300 is formed between the outer tube 200 and the inner tube 100. A flow gap is formed between the bottom surface of the inner tube 100 and the drilled part 213, so that the inner tube 100 is connected to the flow space 300.

[0036] In this embodiment, the drilled portion 213 at the bottom of the outer tube 200 can drill the mounting hole 30 during rotation. The inner tube 100 and the outer tube 200 are coaxially arranged to form a sleeve structure. The outer diameter of the inner tube 100 is smaller than the inner diameter of the outer tube 200, which creates a gap between the outer wall of the inner tube 100 and the inner wall of the outer tube 200. This gap creates an annular flow space 300 inside the outer tube 200, allowing the liquid medium to flow within the flow space 300 between the outer tube 200 and the inner tube 100. Figure 4 In the middle, a flow gap L is formed between the bottom surface of the inner tube 100 and the top surface of the drilled part 213, so that the inner side of the inner tube 100 is connected to the flow space 300.

[0037] For example, the outer tube 200 has a higher material hardness than the inner tube 100, and the inner tube 100 can be made of plastic material, such as polyethylene. The outer tube 200 can be made of metal material, giving it high strength, corrosion resistance, and the ability to withstand high temperatures. The outer tube 200 can be made of high-strength alloy steel material, for example, using metal base materials such as iron, nickel, and cobalt to synthesize alloy steel with high strength, corrosion resistance, and the ability to withstand temperatures above 200°C.

[0038] When installing the coaxial geothermal heat exchanger 10, the outer tube 200 is placed vertically on the ground with its axis extending vertically. The actuator 40 is connected to the top of the outer tube 200 and drives the outer tube 200 to rotate around its axis and apply pressure to the soil layer. For example, the actuator 40 can be a hydraulic actuator. During rotation, the drilled portion 213 at the bottom of the outer tube 200 drills a mounting hole 30 downwards. The drilled portion 213 continues to move downwards during drilling, driving the outer tube 200 downwards, causing it to gradually extend into the drilled mounting hole 30. Once the outer tube 200 has penetrated deep into the soil layer and reached the target depth, the actuator 40 stops driving, stopping the rotation of the outer tube 200. The inner tube 100 is placed inside the outer tube 200, and its top is fixed. For example, the top of the inner tube 100 can be connected to a mounting bracket on the ground or the top of the outer tube 200.

[0039] The top ends of the outer pipe 200 and the inner pipe 100 are respectively used to connect to the heating pipeline 20, so that during the operation of the coaxial geothermal heat exchanger 10, the heating pipeline 20 can provide a liquid medium to the inner pipe 100. For example, the liquid medium can be water. After the liquid medium enters the inner pipe 100 from the top, it flows downward along the inner pipe 100 and flows into the bottom of the outer pipe 200 through the gap at the bottom of the inner pipe 100. After the liquid medium exchanges heat with the soil layer through the wall of the outer pipe 200 at the lower end of the outer pipe 200 and forms a high-temperature medium, it flows upward along the flow space 300 and out of the outer pipe 200, and returns to the heating pipeline 20. After the heat pump 22 extracts heat energy, it heats the target object 23.

[0040] For example, the heating pipeline 20 is equipped with a water pump 21 and a heat pump 22. The water pump 21 is connected to the inner pipe 100 to deliver the liquid medium into the inner pipe 100. The heat pump 22 is connected to the outer pipe 200 to extract the high-temperature medium and deliver it to the target object 23. After completing the heating task, the temperature of the high-temperature medium decreases and returns to the liquid medium state. The target object 23 is connected to the water pump 21, so that the liquid medium can flow back into the inner pipe 100 for heating, thereby forming a circulating heating loop.

[0041] By using the drilling section 213 at the bottom of the outer tube 200 to drill an installation hole 30 on the ground, and using the drilling section 213 and the outer tube 200 body to replace the traditional drill bit and drill rod, the outer tube 200 can be directly installed during the drilling process. The drilling and installation steps are completed in one operation, eliminating the need for cementing and well completion steps, simplifying the construction steps of the coaxial geothermal heat exchanger 10, reducing construction difficulty, effectively reducing construction costs, and shortening the construction cycle, which is conducive to the promotion and application of the coaxial geothermal heat exchanger 10.

[0042] In some embodiments provided in this application, such as Figure 2 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown, the outer tube 200 includes: a first tube 210 and a second tube 220. A drilled portion 213 is provided at the bottom end of the first tube 210. A first connecting portion 211 is provided at the top end of the first tube 210 and the top end of the second tube 220. A second connecting portion 221 is provided at the bottom end of the second tube 220. The second connecting portion 221 is connected to the first connecting portion 211 so that the first tube 210 and the second tube 220 are coaxially connected.

[0043] In this embodiment, the structure of the outer tube 200 is defined. The drilled portion 213 is connected to the first tube 210 by integral molding or welding, and the connection is sealed to prevent leakage. The first tube 210 is located below the second tube 220. The first tube 210 and the second tube 220 can be connected by the first connecting portion 211 and the second connecting portion 221. The inner and outer diameters of the first tube 210 and the second tube 220 are the same, so that after the first tube 210 and the second tube 220 are connected, their inner and outer walls are coplanar. The first tube 210 and the second tube 220 are connected vertically to form the outer tube 200, which gives the outer tube 200 a split structure, facilitating the installation of the outer tube 200.

[0044] When installing the outer pipe 200, the first pipe fitting 210 is placed vertically on the ground. The driver 40 is connected to the top of the first pipe fitting 210 and drives the first pipe fitting 210 to rotate, causing the drilling part 213 at the bottom of the first pipe fitting 210 to drill out the mounting hole 30. During the drilling process, the drilling part 213 drives the first pipe fitting 210 downwards until the first pipe fitting 210 reaches the preset depth. When the height of the first pipe fitting 210 above the ground reaches the target height, the driver 40 stops driving, and the first pipe fitting 210 stops rotating. The second pipe fitting 220 is connected to the top of the first pipe fitting 210. The driver 40 is connected to the top of the second pipe fitting 220 and drives the second pipe fitting 220 to rotate, so that the drilling part 213 continues to drill downwards until the depth of the drilling part 213 reaches the target depth, completing the installation of the outer pipe 200.

[0045] The two ends of the second pipe fitting 220 are respectively provided with a first connecting part 211 and a second connecting part 221, so that multiple second pipe fittings 220 can be connected in series, which further improves the installation flexibility of the outer pipe 200. In addition, the number of second pipe fittings 220 can be adjusted according to different installation depth requirements, so that the outer pipe 200 can meet more installation depth requirements and expand the application range of the outer pipe 200.

[0046] For example, the first connecting portion 211 and the second connecting portion 221 can be internally threaded and externally threaded, respectively. The first pipe fitting 210 and the second pipe fitting 220 are integrally formed to improve the structural strength of the outer pipe 200, enabling the outer pipe 200 to adapt to harsh underground installation environments. The length of the first pipe fitting 210 and the second pipe fitting 220 is 1 meter to 3 meters.

[0047] In some embodiments provided in this application, such as Figure 5 , Figure 7 , Figure 8 and Figure 9As shown, a first sealing part 212 is provided below the first connecting part 211, and a second sealing part 222 is provided below the second connecting part 221. The outer tube 200 also includes a sealing element 230. When the first connecting part 211 and the second connecting part 221 are connected, the sealing element 230 is located between the first sealing part 212 and the second sealing part 222.

[0048] In this embodiment, the inner diameter of the first sealing part 212 is slightly larger than the inner diameter of the first pipe fitting 210, and the outer diameter of the second sealing part 222 is slightly smaller than the outer diameter of the second pipe fitting 220. The sealing member 230 is disposed on the inner wall of the first sealing part 212 or the outer wall of the second sealing part 222, so that after the first connecting part 211 and the second connecting part 221 are engaged, a small gap is formed between the first sealing part 212 and the second sealing part 222. The sealing member 230 is located between the first sealing part 212 and the second sealing part 222 to seal the connection position, ensure the sealing of the connection position of the outer pipe 200, and prevent the liquid medium from leaking out along the connection gap.

[0049] For example, the seal 230 can be an annular sealing ring or sealing strip, and there can be multiple seals 230, which are spaced apart along the axial direction.

[0050] In some embodiments provided in this application, such as Figure 1 As shown, the drilled part 213 is a cone, and the maximum outer diameter of the drilled part 213 is greater than the outer wall diameter of the outer tube 200.

[0051] In this embodiment, the drilled portion 213 is cone-shaped with a pointed bottom. The drilled portion 213 can be a drill bit, and one or more drill bit threads are provided on the drilled portion 213 to make it easier to drill into the rock and soil layer, thereby improving the drilling efficiency of the drilled portion 213 and improving the installation efficiency of the outer tube 200.

[0052] The maximum outer diameter of the borehole section 213 is greater than the outer wall diameter of the outer tube 200, ensuring that only the borehole section 213 encounters resistance when the outer tube 200 drills into the soil and rock layer. The diameter of the installation hole 30 drilled by the borehole section 213 is greater than the outer diameter of the outer tube 200, leaving an annular gap between the straight tubular section of the outer tube 200 and the soil and rock layer. This prevents the outer tube 200 from encountering resistance on its wall during drilling, thus affecting drilling efficiency and allowing the outer tube 200 to smoothly drill into the deep soil and rock layer. The difference between the maximum outer diameter of the borehole section 213 and the outer wall diameter of the outer tube 200 is greater than or equal to 0.1 times the maximum outer diameter of the borehole section 213.

[0053] In some embodiments provided in this application, such as Figure 3As shown, the top surface of the inner pipe 100 is 10cm to 30cm higher than the top surface of the outer pipe 200. And / or the heating pipe 20 is used to supply liquid medium to the inner pipe 100, the liquid medium is heated at the bottom of the outer pipe 200 to form a high-temperature medium, and the flow distance is related to the heat exchange power, the initial temperature of the liquid medium, the high temperature of the liquid medium, and the temperature of the soil layer at the bottom of the outer pipe 200.

[0054] In this embodiment, by reasonably limiting the distance by which the inner tube 100 extends out of the outer tube 200, it is convenient for the inner tube 100 and the outer tube 200 to be connected to the heating pipeline 20 respectively, thereby improving the installation convenience of the coaxial geothermal heat exchanger 10.

[0055] The bottom of the inner tube 100 is suspended inside the outer tube 200, so that the bottom of the inner tube 100 is connected to the flow space 300, and the flow distance L satisfies formula (1):

[0056] (1);

[0057] In the formula, Q req The preset heat exchange power T for the coaxial geothermal heat exchanger 10 in T represents the temperature of the liquid medium at the inlet of the inner tube 100, i.e., the initial temperature of the bulk liquid medium. out T represents the high-temperature medium temperature at the outlet of the outer pipe (200 mm), i.e., the high-temperature temperature of the bulk liquid medium. soil λ represents the temperature of the soil and rock layer at the bottom of the outer pipe (200 mm). eff The combined thermal conductivity of the outer tube 200 and the soil layer, T is the allowable temperature difference threshold (usually taken as 5℃ to 10℃).

[0058] By reasonably limiting the flow gap, the bottoms of the inner tube 100 and the outer tube 200 can meet the heat exchange efficiency, thus ensuring the heating effect of geothermal energy on the liquid medium.

[0059] A second aspect of this application provides a method for installing a coaxial geothermal heat exchanger, such as... Figure 14 As shown, this installation method is used to install a coaxial geothermal heat exchanger as provided in the first aspect embodiment via a driver and operating device. The installation method includes:

[0060] Step 101: Control the driver to drive the outer tube to rotate according to the drilling parameters;

[0061] Step 102: Control the driver to drive the drilling part at the bottom of the outer tube to drill a mounting hole in the ground, so that at least part of the outer tube is located in the mounting hole;

[0062] Step 103: When the outer tube reaches the target depth, control the driver to stop rotating;

[0063] Step 104: The control device places the inner tube inside the outer tube, so that a flow space is formed between the inner tube and the outer tube, a flow gap is formed between the bottom surface of the inner tube and the drilled part, and the inner side of the inner tube is connected to the flow space.

[0064] Step 105: The control device connects the outer pipe and the inner pipe to the heating pipeline respectively.

[0065] In this embodiment, the actuator can be a hydraulic actuator, and the operating device can be a robotic arm or construction equipment. When installing the coaxial geothermal heat exchanger, the operating device places the outer pipe vertically on the ground, with its axis extending vertically. The actuator connects to the top of the outer pipe and drives the outer pipe to rotate around its axis, applying pressure to the soil layer. During rotation, the drilled portion at the bottom of the outer pipe drills an installation hole downwards. The drilled portion continues to move downwards during drilling, driving the outer pipe downwards, gradually extending it into the drilled installation hole. Once the outer pipe enters the deep soil layer and reaches the target depth, the actuator stops driving, causing the outer pipe to stop rotating. The operating device places the inner pipe inside the outer pipe and fixes the top of the inner pipe. Exemplarily, the top of the inner pipe can be connected to a mounting bracket on the ground or the inner wall of the outer pipe.

[0066] The operating device connects the top of the outer pipe and the top of the inner pipe to the heating pipeline, enabling the heating pipeline to supply a liquid medium to the inner pipe during operation of the coaxial geothermal heat exchanger. For example, the liquid medium can be water. After entering the inner pipe from the top, the liquid medium flows downwards along the inner pipe, flowing into the bottom of the outer pipe through a gap at the bottom of the inner pipe. At the lower end of the outer pipe, the liquid medium exchanges heat with the soil and rock layer through the outer pipe wall, forming a high-temperature medium. It then flows upwards along the flow space out of the outer pipe and returns to the heating pipeline. The heat energy is then extracted by the heat pump to heat the target object.

[0067] By drilling an installation hole in the ground using the borehole section at the bottom of the outer tube, and replacing the traditional drill bit and drill rod with the borehole section and the outer tube body, the outer tube can be directly installed during the drilling process. The drilling and installation steps are completed in one operation, eliminating steps such as cementing and well completion. This simplifies the construction steps of the coaxial geothermal heat exchanger, reduces construction difficulty, effectively lowers construction costs, and shortens the construction cycle, which is conducive to the promotion and application of coaxial geothermal heat exchangers.

[0068] In some embodiments provided in this application, the outer tube includes a first fitting and a second fitting, and step 101, which controls the driver to drive the outer tube to rotate, specifically includes:

[0069] Step 1011: Control the driver to drive the first pipe fitting to rotate according to the drilling parameters;

[0070] Step 1012: When the height of the first pipe protruding above the ground reaches the target height, control the driver to stop rotating;

[0071] Step 1013: Control the operating device to connect the second pipe fitting to the top of the first pipe fitting;

[0072] Step 1014: Control the driver to drive the second pipe to rotate.

[0073] In this embodiment, the installation method of the outer tube is defined. The first pipe fitting and the second pipe fitting are connected vertically to form the outer tube, so that the outer tube forms a split structure, which facilitates the installation of the outer tube.

[0074] When installing the outer pipe, such as Figure 10 As shown, the operating device places the first pipe vertically on the ground. The driver connects to the top of the first pipe and drives it to rotate, causing the drilling part at the bottom of the first pipe to drill an installation hole. During drilling, the drilling part moves the first pipe downwards until it reaches a preset depth. When the height of the first pipe protruding from the ground reaches the target height, the driver stops driving, causing the first pipe to stop rotating. Figure 11 As shown, the operating device connects the second pipe fitting to the top of the first pipe fitting, and the driver is connected to the top of the second pipe fitting. The driver drives the second pipe fitting to rotate, so that the drilling part continues to drill downwards until the drilling part reaches the target depth, thus completing the installation of the outer pipe.

[0075] The two ends of the second pipe fitting are respectively provided with a first connecting part and a second connecting part, so that multiple second pipe fittings can be connected in series, which further improves the flexibility of the outer pipe installation. Moreover, the number of second pipe fittings can be adjusted according to different installation depth requirements, so that the outer pipe can meet more installation depth requirements.

[0076] In some embodiments provided in this application, the drilling parameters include: target rotational speed and target downward pressure. Step 101, which controls the actuator to drive the outer casing rotation according to the drilling parameters, specifically includes:

[0077] Step 1015: Based on the maximum outer diameter of the borehole and the target borehole depth, calculate the target rotational speed and target downward pressure of the driver.

[0078] Step 1016: Based on the target rotation speed and the target downward pressure, control the driver to drive the outer tube to rotate.

[0079] In this embodiment, before drilling step 1011, the drilling parameters of the actuator are determined. The target rotational speed of the actuator is the minimum rotational speed, the target downward pressure of the actuator is the maximum downward pressure, and the soil layer is a soil layer or a gravel-soil mixture. Based on the properties of the soil layer (compressive strength σ, friction coefficient μ) and the target depth H, the minimum rotational speed ω of the actuator is calculated using formulas (2) and (3). min and the maximum downward pressure F crit :

[0080]

[0081] In the formula, D d H is the maximum outer diameter of the borehole, K1 and K2 are empirical coefficients (K1 = 0.15 to 0.25, K2 = 1.2 to 1.5), and H is the target depth.

[0082] By limiting the minimum rotational speed of the actuator, sufficient rotational speed is ensured for the drilling section to overcome the shear resistance of the soil and rock layers, enabling smooth drilling operations and preventing jamming. By limiting the maximum downward pressure of the actuator, sufficient driving force is provided for the outer tube to extend downwards, while preventing deformation of the outer tube due to excessive pressure.

[0083] In some embodiments provided in this application, step 102, which involves controlling the driver to drive the drilling portion at the bottom of the outer tube to drill an installation hole in the ground, specifically includes:

[0084] Step 1021: Based on the maximum outer diameter of the drilled part and the outer diameter of the outer tube, calculate the difference between the radius of the mounting hole and the radius of the outer tube;

[0085] Step 1022: Based on the difference, control the operating device to maintain a preset distance between the outer pipe and the rock wall.

[0086] In this embodiment, the maximum outer diameter of the borehole is greater than the outer wall diameter of the outer tube, so that only the borehole encounters resistance when the outer tube is drilled into the soil and rock layer. The diameter of the installation hole drilled by the borehole is greater than the outer diameter of the outer tube, so that there is an annular blank space between the straight tubular section of the outer tube and the soil and rock layer, avoiding the pipe wall of the outer tube from encountering resistance when drilling and affecting the drilling efficiency, so that the outer tube can be smoothly drilled into the deep soil and rock layer.

[0087] Determine the distance between the outer pipe and the rock wall before drilling the installation hole. Figure 4 In the middle, the difference between the radius of the mounting hole and the radius of the outer tube, that is, the width δ of the annular blank space, is kept at a preset distance δ between the outer tube and the rock wall, and δ satisfies formula (4):

[0088] (4);

[0089] In the formula, D p D is the outer diameter of the outer tube. d This is the maximum outer diameter of the drilled section.

[0090] In some embodiments provided in this application, the heating pipeline is used to supply a liquid medium to the inner pipe, the liquid medium is heated at the bottom of the outer pipe to form a high-temperature medium, and step 104, in which the control device places the inner pipe into the outer pipe, specifically includes:

[0091] Step 1041: Control the operating device to operate the inner tube so that the top surface of the inner tube is 10cm to 30cm higher than the top surface of the outer tube.

[0092] Step 1042: Calculate the flow spacing based on the heat exchange power, the initial temperature of the liquid medium, the high temperature of the liquid medium, and the temperature of the soil and rock layer at the bottom of the outer pipe.

[0093] Step 1043: Control the installation height of the inner tube according to the flow spacing.

[0094] In this embodiment, by reasonably limiting the distance between the inner tube and the outer tube, it is convenient for the inner tube and the outer tube to be connected to the heating pipeline respectively, thereby improving the installation convenience of the coaxial geothermal heat exchanger.

[0095] The bottom of the inner tube is suspended inside the outer tube, so that the bottom of the inner tube is connected to the flow space. The suspended flow distance L satisfies formula (1). By reasonably limiting the flow distance, the bottom of the inner tube and the outer tube can meet the heat exchange efficiency, thus ensuring the heating effect of geothermal energy on the liquid medium.

[0096] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0097] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0098] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0099] The above are merely some embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coaxial geothermal heat exchanger, characterized in that, include: The device consists of an inner tube and an outer tube. The outer tube is fitted over the outer side of the inner tube. The bottom end of the outer tube has a drilled hole for drilling an installation hole in the ground. The installation hole is used to accommodate the outer tube. A flow space is formed between the outer tube and the inner tube. A flow gap is formed between the bottom surface of the inner tube and the drilled hole, allowing the inner tube to connect with the flow space. The drilled portion is a cone, the maximum outer diameter of the drilled portion is greater than the outer wall diameter of the outer tube, and the difference between the maximum outer diameter of the drilled portion and the outer wall diameter is greater than or equal to 0.05 times the maximum outer diameter of the drilled portion. The outer tube is used to drive the actuator to rotate according to drilling parameters, which include: target rotational speed ω. min and the target downward pressure F crit ,in, In the formula, D d Where σ is the maximum outer diameter of the borehole, K1 and K2 are empirical coefficients, K1 = 0.15 to 0.25, K2 = 1.2 to 1.5, H is the target depth, σ is the compressive strength of the soil layer, and μ is the friction coefficient of the soil layer.

2. The coaxial geothermal heat exchanger according to claim 1, characterized in that, The outer tube includes: The first pipe fitting has a drilled portion located at its bottom end. The second pipe fitting has a first connecting part at the top end of the first pipe fitting and the top end of the second pipe fitting, and a second connecting part at the bottom end of the second pipe fitting. The second connecting part is connected to the first connecting part so that the first pipe fitting and the second pipe fitting are coaxially connected.

3. The coaxial geothermal heat exchanger according to claim 2, characterized in that, A first sealing portion is provided below the first connecting portion, and a second sealing portion is provided below the second connecting portion. The outer tube further includes: When the first connecting portion is connected to the second connecting portion, the sealing element is located between the first sealing portion and the second sealing portion.

4. The coaxial geothermal heat exchanger according to claim 1, characterized in that, The top surface of the inner tube is 10cm to 30cm higher than the top surface of the outer tube; and / or The heating pipeline is used to supply a liquid medium to the inner pipe, and the liquid medium is heated at the bottom of the outer pipe to form a high-temperature medium. The flow spacing is related to the heat exchange power, the initial temperature of the liquid medium, the high temperature of the liquid medium, and the temperature of the soil layer at the bottom of the outer pipe.

5. A method for installing a coaxial geothermal heat exchanger, characterized in that, The installation method for installing the coaxial geothermal heat exchanger as described in any one of claims 1 to 4 via a driver and operating device includes: The actuator is controlled to drive the outer tube to rotate according to the drilling parameters; The driver is controlled to drive the drilling section at the bottom of the outer tube to drill a mounting hole in the ground, so that at least part of the outer tube is located in the mounting hole; When the outer tube reaches the target depth, the actuator is controlled to stop rotating. The operating device is controlled to place the inner tube inside the outer tube, so that a flow space is formed between the inner tube and the outer tube, a flow gap is formed between the bottom surface of the inner tube and the drilled part, and the inner side of the inner tube is connected to the flow space. The operating device is controlled to connect the outer pipe and the inner pipe to the heating pipeline respectively; The step of controlling the driver to drive the drilling section at the bottom of the outer tube to drill an installation hole in the ground specifically includes: Based on the maximum outer diameter of the drilled portion and the outer diameter of the outer tube, calculate the difference between the radius of the mounting hole and the radius of the outer tube; Based on the difference, the operating device is controlled to maintain a preset distance between the outer tube and the rock wall; wherein the preset distance is greater than or equal to 0.05 times the maximum outer diameter of the borehole. The drilling parameters include: target rotational speed and target downward pressure. The step of controlling the actuator to drive the outer casing rotation according to the drilling parameters specifically includes: Based on the maximum outer diameter of the borehole and the target borehole depth, the target rotational speed ω of the driver is determined. min and the target downward pressure F crit ; In the formula, D d Where σ is the maximum outer diameter of the borehole, K1 and K2 are empirical coefficients, K1 = 0.15 to 0.25, K2 = 1.2 to 1.5, H is the target depth, σ is the compressive strength of the soil and rock layer, and μ is the friction coefficient of the soil and rock layer. The actuator is controlled to drive the outer tube to rotate based on the target rotation speed and the target downward pressure.

6. The installation method according to claim 5, characterized in that, The outer tube includes a first fitting and a second fitting. The step of controlling the driver to drive the outer tube to rotate specifically includes: The driver is controlled to drive the first pipe fitting to rotate according to the drilling parameters; When the height of the first pipe protruding above the ground reaches the target height, control the driver to stop rotating; The operating device is controlled to connect the second pipe fitting to the top of the first pipe fitting; The driver is controlled to drive the second pipe to rotate.

7. The installation method according to claim 5, characterized in that, The heating pipeline is used to supply a liquid medium to the inner pipe, the liquid medium is heated at the bottom of the outer pipe to form a high-temperature medium, and the step of controlling the operating device to place the inner pipe inside the outer pipe specifically includes: The operating device is controlled to operate the inner tube so that the top surface of the inner tube is 10cm to 30cm higher than the top surface of the outer tube; The flow spacing is calculated based on the heat exchange power, the initial temperature of the liquid medium, the high temperature of the liquid medium, and the temperature of the soil and rock layer at the bottom of the outer pipe. The installation height of the inner tube is controlled according to the flow spacing.

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