Device for improving heat exchange efficiency of medium-deep geothermal underground heat exchange system and heat exchange method

Abstract

The invention discloses a device for improving the heat exchange efficiency of a middle-deep layer geothermal underground heat exchange system and a heat exchange method, and relates to the technical field of heat exchange devices. A fluid conversion device; the fluid conversion device comprises an inner pipe connecting pipe, an inner side pipe and an outer side pipe, a heat exchange groove is formed in the outer side pipe, and a first heat exchange cavity is formed between the inner side pipe and the outer side pipe; a second heat exchange cavity is formed between the inner pipe connecting pipe and the inner side pipe; a third heat exchange cavity is formed between the sleeve and the fluid conversion device; an outer side backflow opening is formed in the position, close to the bottom, of the pipe wall of the outer side pipe and communicates with the third heat exchange cavity and the first heat exchange cavity. An inner side backflow opening is formed in the position, close to the top, of the pipe wall of the inner side pipe and communicates with the second heat exchange cavity and the first heat exchange cavity. Inner side convex ribs are arranged on the outer wall of the inner side pipe, outer side convex ribs are arranged on the outer wall of the outer side pipe, and sleeve convex ribs are arranged on the inner circumferential side wall of the sleeve. The heat exchange effect of the heat exchange system can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of heat exchange devices, and in particular to a device and a heat exchange method for improving the heat exchange efficiency of a mid-deep geothermal underground heat exchange system. Background Art

[0002] As a key method for developing and utilizing geothermal energy, deep- and medium-layer geothermal downhole heat exchange systems have attracted significant attention in recent years. This technology, which combines downhole heat exchange technology with ground-based heat pump systems, demonstrates enormous potential for application in the energy sector. It is crucial for improving energy efficiency and environmental protection, contributing to optimizing my country's energy structure, reducing dependence on fossil fuels, and promoting the development of green buildings and low-carbon cities. With the growing global demand for clean energy, the development and utilization of deep- and medium-layer geothermal resources has become a research hotspot, with numerous research teams and businesses investing significant resources in the development and promotion of related technologies.

[0003] In traditional mid- to deep-layer geothermal development and utilization, a common approach to addressing geothermal energy extraction and utilization is to use conventional downhole heat exchange systems in conjunction with surface heat pumps. Some projects increase the length of downhole heat exchange tubes to increase the heat exchange area, thereby enhancing heat exchange. Others focus on optimizing the performance of surface heat pump systems, such as improving compressor efficiency and adjusting the refrigerant circulation path, in the hope of better converting low-temperature heat energy captured from the ground into usable high-temperature heat. Other projects attempt to adjust the flow rate of downhole fluids to alter the rate of heat transfer. These approaches have, to a certain extent, met the geothermal energy development needs of some regions.

[0004] However, existing downhole heat exchange systems for medium- and deep-layer geothermal resources have significant drawbacks. Due to significant variations in geological conditions across different regions, drilling depths are often limited. This results in insufficient heat transfer capacity, hindering the efficient development and utilization of medium- and deep-layer geothermal resources and becoming a bottleneck restricting further development in this field. Summary of the Invention

[0005] In order to improve the heat exchange effect of a heat exchange system, the present application provides a device and a heat exchange method for improving the heat exchange efficiency of a medium-deep geothermal downhole heat exchange system.

[0006] In a first aspect, the present application provides a device for improving the heat exchange efficiency of a medium-deep geothermal downhole heat exchange system, which adopts the following technical solution: A device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system, comprising an inner tube; a fluid conversion device, disposed at the bottom of the inner tube; The fluid conversion device includes an inner tube connecting tube, an inner tube, and an outer tube, wherein a heat exchange groove is formed in the outer tube, the inner tube is arranged on the outer tube and located in the heat exchange groove, and a first heat exchange cavity is formed between the inner tube and the outer tube; The inner tube connecting pipe is arranged in the inner tube, a second heat exchange cavity is formed between the inner tube connecting pipe and the inner tube, and the inner tube is connected to the inner tube connecting pipe and is coaxially arranged; a sleeve, sleeved on the outer peripheral side of the fluid conversion device, wherein a third heat exchange chamber is formed between the sleeve and the fluid conversion device; An outer return port is formed near the bottom of the outer tube wall, and the outer return port is connected to the third heat exchange cavity and the first heat exchange cavity; An inner return port is formed near the top of the inner tube wall, and the inner return port is connected to the second heat exchange cavity and the first heat exchange cavity; The inner tube outer wall is provided with inner convex ribs, the outer tube outer wall is provided with outer convex ribs, and the inner circumferential side wall of the sleeve is provided with sleeve convex ribs. There are multiple inner convex ribs, outer convex ribs, and sleeve convex ribs respectively and they are arranged at intervals along the circumferential direction.

[0007] By adopting the above technical solution, different heat exchange chambers are constructed using the inner tube, fluid conversion device and casing, so that the fluid flows in each heat exchange chamber in turn, increasing the water flow length at the bottom of the geothermal well and effectively improving the heat exchange length; and by arranging circumferentially spaced ribs on each component to form turbulent flow of the fluid, the heat exchange efficiency of the medium-deep geothermal downhole heat exchange system is improved, which helps to solve the problem of insufficient heat exchange capacity of the downhole heat exchange system due to limited drilling depth, and promotes the efficient development and utilization of medium-deep geothermal resources; at the same time, the setting of the fluid conversion device can also be used as a counterweight for the inner tube.

[0008] Optionally, the inner convex rib, the outer convex rib, and the sleeve convex rib respectively extend upward in a spiral shape.

[0009] By adopting the above technical solution, the inner pipe extracts the fluid in the geothermal well, causing the fluid above the geothermal well to flow into the third heat exchange chamber for heat exchange. The spirally upward extending casing ribs and the outer ribs cause the fluid to form turbulence. After the fluid flows into the first heat exchange chamber through the outer return port, the spirally upward extending inner ribs cause the fluid to form turbulence again, thereby strengthening the fluid disturbance and increasing the contact area and contact time between the fluid and the wall of each heat exchange chamber, thereby improving the heat exchange efficiency of the medium and deep geothermal well underground heat exchange system.

[0010] Optionally, the spiral angles of the inner convex rib, the outer convex rib, and the sleeve convex rib are 30°-60°.

[0011] By adopting the above technical solution, the inner convex ribs, outer convex ribs and casing convex ribs are made to have specific spiral angles, which can further enhance the turbulence effect of the fluid flowing through them, thereby improving the heat exchange efficiency of the medium-deep geothermal downhole heat exchange system.

[0012] Optionally, the inner convex rib, the outer convex rib and the sleeve convex rib respectively extend in the circumferential direction.

[0013] By adopting the above technical solution, the device for improving the heat exchange efficiency of the medium-deep geothermal downhole heat exchange system, which is composed of the inner tube, the fluid conversion device, and the casing, increases the contact time and contact area between the fluid and the inner wall of each heat exchange cavity when flowing in each heat exchange cavity due to the inner convex ribs, the outer convex ribs, and the casing convex ribs extending in the circumferential direction, thereby promoting the formation of turbulence in the fluid and improving the heat exchange efficiency of the medium-deep geothermal downhole heat exchange system.

[0014] Optionally, the horizontal cross-sections of the inner convex rib, the outer convex rib, and the sleeve convex rib are rectangular, triangular, or trapezoidal.

[0015] By adopting the above technical solution, the horizontal cross-sections of the inner convex ribs, outer convex ribs and casing convex ribs are set to be rectangular, triangular or trapezoidal, which can change the flow state of the fluid flowing through the convex ribs, enhance the disturbance of the fluid, further promote heat exchange, and effectively improve the heat exchange efficiency of the medium and deep geothermal underground heat exchange system.

[0016] Optionally, the height of the inner rib is 5%-15% of the inner diameter of the inner tube; The height of the outer rib is 5%-15% of the inner diameter of the outer tube; The height of the sleeve rib is 5%-15% of the inner diameter of the sleeve.

[0017] By adopting the above technical solution, the heights of the inner convex ribs, outer convex ribs and casing convex ribs are set to 5%-15% of the inner tube inner diameter, outer tube inner diameter and casing inner diameter respectively, which can make the fluid flowing through each heat exchange cavity form turbulence of appropriate intensity, fully enhance the degree of fluid disturbance, and thus significantly improve the heat exchange efficiency of the entire medium-deep geothermal downhole heat exchange system.

[0018] Optionally, the outer rib and the outer wall of the sleeve rib are offset from each other.

[0019] By adopting the above technical solution, under the coordinated action of the outer convex ribs and the casing convex ribs, the fluid can further form complex turbulence when flowing through the third heat exchange chamber, enhancing the fluid disturbance, thereby improving the heat exchange efficiency of the medium-deep geothermal downhole heat exchange system.

[0020] Optionally, the outer wall of the outer tube is rotatably connected to an outer ring, the outer wall of the inner tube is rotatably connected to an inner ring, the outer ribs are connected to the outer ring, and the inner ribs are connected to the inner ring; A receiving groove is provided in the top wall of the outer tube, which is connected to the inner tube connecting tube. The outer tube is rotatably connected to a rotating shaft located in the receiving groove. A plurality of rotating blades are provided on the outer circumference of the rotating shaft at intervals along the circumferential direction. The rotating blades extend into the inner tube connecting tube. A control component is provided in the outer tube. When the rotating shaft rotates, the control component controls the outer ring and the inner ring to rotate respectively.

[0021] By adopting the above technical solution, when the fluid flows in the inner tube connecting tube and impacts the rotating blades to rotate the rotating shaft, the control component can be used to drive the outer ring and the inner ring to rotate, thereby rotating the outer convex ribs and the inner convex ribs, further enhancing the fluid disturbance effect, promoting fluid mixing and heat transfer, and effectively improving the heat exchange efficiency.

[0022] Optionally, the control assembly includes an outer gear ring, an inner gear ring, a connecting gear, a connecting shaft, a connecting ball, a connecting wheel, a transmission shaft, a transmission belt and a transmission wheel; The outer gear ring is arranged on the inner peripheral side wall of the outer ring, and the inner gear ring is arranged on the inner peripheral side wall of the inner ring; There are multiple connecting shafts that are rotatably connected to the outer tube and the inner tube respectively. The connecting gears are arranged on the outer circumference of the connecting shafts and correspond one to one. The connecting gears are respectively engaged with the inner gear ring and the outer gear ring; The connecting wheel is arranged at the end of the connecting shaft and rotates in the top wall of the outer tube, and the outer peripheral side wall of the connecting wheel is provided with connecting grooves evenly spaced along the circumferential direction; A sliding groove surrounding the connecting wheel is opened in the top wall of the outer tube, and a plurality of connecting balls are evenly slidably connected in the sliding groove, and the connecting balls are stuck in the connecting groove; The transmission shaft is rotatably connected to the top wall of the outer tube, and the transmission belt is connected end to end and sleeved on the transmission shaft and the outer circumference of the rotation shaft; The transmission wheel is arranged on the outer peripheral side of the transmission shaft. The outer peripheral side of the transmission wheel is provided with transmission grooves evenly spaced along the circumferential direction. The connecting balls are stuck in the transmission grooves.

[0023] By adopting the above technical solution, the control component can enable the rotating shaft to drive the outer ring and the inner ring to rotate, thereby causing the inner convex ribs and the outer convex ribs to rotate, further enhancing the fluid turbulence effect and improving the heat exchange efficiency of the medium and deep geothermal downhole heat exchange system.

[0024] In a second aspect, the present application provides a heat exchange method for improving the heat exchange efficiency of a medium-deep geothermal downhole heat exchange system, using the following technical solutions: A heat exchange method for improving the heat exchange efficiency of a medium-deep geothermal downhole heat exchange system comprises the following steps: S1: placing the casing into the geothermal well and filling fillers between the outer wall of the casing and the wall of the geothermal well; S2: placing the fluid heat exchange device, connecting the inner tube to the inner tube connecting tube, and then placing the fluid heat exchange device into the casing, wherein the inner tube is connected to the ground heat pump; S3: Fluid heat exchange. The inner tube extracts the fluid in the geothermal well. At this time, the fluid above the geothermal well flows into the third heat exchange chamber for heat exchange. The fluid forms turbulence after passing through the casing ribs and the outer ribs. Then the fluid flows into the first heat exchange chamber after passing through the outer return port. Then the fluid forms turbulence after passing through the inner ribs, and then flows into the second heat exchange chamber through the inner return port. Finally, the inner tube extracts the fluid after heat exchange through the inner tube connecting pipe.

[0025] By adopting the above technical solution, a heat exchange device is composed of components such as casing, inner tube, and fluid conversion device, which can circulate and exchange geothermal fluid; placing casing in the geothermal well and filling it with filler can ensure the stability of the casing; after connecting the inner tube and the inner tube connecting pipe, the casing is placed and connected to the ground heat pump to ensure that the fluid circulation loop is established; the inner tube draws geothermal fluid, causing the fluid to flow in each heat exchange cavity, and forming turbulence through the casing ribs, outer ribs, and inner ribs, increasing the fluid disturbance and mixing degree, enhancing the heat transfer effect, and improving the heat exchange efficiency of the medium-deep geothermal downhole heat exchange system, thereby helping to solve the problem of insufficient heat exchange capacity of the downhole heat exchange system due to limited drilling depth, and promoting the efficient development and utilization of medium-deep geothermal resources.

[0026] In summary, this application has at least one of the following beneficial effects: 1. By setting up multiple heat exchange chambers and reflux ports, the fluid is allowed to flow and exchange heat in each heat exchange chamber in sequence, thereby improving the heat exchange efficiency of the deep-seated geothermal downhole heat exchange system and solving the problem of insufficient heat exchange capacity caused by limited drilling depth; 2. The overall design of the device can effectively extract mid- to deep-layer geothermal energy. Combined with the ground heat pump system, it can improve energy utilization efficiency, improve environmental protection, optimize the energy structure, and reduce dependence on fossil fuels. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application; Figure 2 It is a schematic diagram of the internal structure of an embodiment of the present application; Figure 3 This is a schematic diagram of the state in which the rib extends along the circumferential direction in an embodiment of the present application; Figure 4 This is a schematic diagram of the structure when the outer rib is connected to the outer ring in an embodiment of the present application; Figure 5is a schematic internal cross-sectional view of an embodiment of the present application; Figure 6 yes Figure 5 A magnified schematic diagram of part A; Figure 7 yes Figure 5 An enlarged schematic diagram of part B; Figure 8 is a schematic diagram of the internal cross-section of the outer tube in the embodiment of the present application; Figure 9 This is a schematic diagram of the connection structure between the rotating shaft and the transmission shaft in an embodiment of the present application; Figure 10 This is a schematic diagram of the connection structure between the transmission wheel and the connection ball in an embodiment of the present application; Figure 11 It is a schematic diagram of the steps of fluid heat exchange in an embodiment of the present application.

[0028] Figure numerals: 1. inner tube; 2. fluid conversion device; 3. inner tube connecting tube; 31. second heat exchange chamber; 4. inner tube; 41. first heat exchange chamber; 42. inner return port; 43. inner rib; 44. inner ring; 5. outer tube; 51. heat exchange groove; 52. outer return port; 53. outer rib; 54. outer ring; 55. accommodating groove; 56. rotating shaft; 57. rotating blade; 6. sleeve; 61. third heat exchange chamber; 62. sleeve rib; 7. slide groove; 8. outer gear ring; 81. inner gear ring; 82. connecting gear; 83. connecting shaft; 84. connecting ball; 85. connecting wheel; 851. connecting groove; 86. transmission shaft; 87. transmission belt; 88. transmission wheel; 881. transmission groove. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-11 This application is described in further detail.

[0030] The embodiment of the present application discloses a device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system.

[0031] Example 1 See also Figure 1 The device for improving the heat exchange efficiency of a medium-deep geothermal downhole heat exchange system provided in an embodiment of the present application includes an inner tube 1, a fluid conversion device 2 and a casing 6, wherein the fluid conversion device 2 is arranged at the bottom of the inner tube 1, and the casing 6 is arranged on the outer peripheral side of the fluid conversion device 2. Through such an arrangement, multiple heat exchange chambers are formed, the heat exchange area and path are increased, and the effect of improving the heat exchange efficiency is achieved. This is because the multiple heat exchange chambers allow the fluid to undergo multiple heat exchanges in different areas, extending the heat exchange time and path, so that it can more fully exchange heat with the surrounding environment.

[0032] See also Figure 1 and Figure 2Specifically, the fluid conversion device 2 includes an inner tube connecting tube 3, an inner tube 4, and an outer tube 5. A heat exchange groove 51 is provided in the outer tube 5, and the inner tube 4 is fixedly installed on the outer tube 5. The inner tube 4 is located in the heat exchange groove 51, and a first heat exchange cavity 41 is formed between the outer wall of the inner tube 4 and the inner peripheral wall of the outer tube 5. The outer tube 5 is generally made of a metal material with good thermal conductivity, such as copper or aluminum alloy. Of course, some special ceramic materials can also be used as long as they have good thermal conductivity. The inner tube 4 also needs to have good thermal conductivity, and its material is similar to that of the outer tube 5.

[0033] The inner connecting tube 3 is disposed within the inner tube 4 and is fixedly connected to the outer tube 5. The inner connecting tube 3 and the outer tube 5 are coaxially arranged, and the top of the inner connecting tube 3 protrudes beyond the outer tube 5. A gap exists between the bottom opening of the inner connecting tube 3 and the bottom wall of the outer tube 5. A second heat exchange chamber 31 is formed between the inner connecting tube 3 and the inner tube 4. The inner tube 1 and the inner connecting tube 3 are coaxially arranged. The inner connecting tube 3 connects the inner tube 1 to the entire fluid conversion device 2 and is preferably made of a material with good thermal conductivity, such as stainless steel.

[0034] In the embodiment of the present application, the inner tube connecting tube 3 and the inner tube 1 can be connected by a threaded connection. This connection method facilitates installation and disassembly, and also facilitates subsequent maintenance and repair. Furthermore, the threaded connection ensures a tight connection, reducing the possibility of fluid leakage. Of course, in other embodiments, the inner tube connecting tube 3 and the inner tube 1 can also be connected by welding. Welding can make the connection more secure, reduce the thermal resistance at the connection, and improve heat exchange efficiency.

[0035] The inner tube 4 has multiple inner ribs 43 fixedly attached to its outer wall, evenly spaced along the circumference. The outer tube 5 has multiple outer ribs 53 fixedly attached to its outer wall, evenly spaced along the circumference. The sleeve 6 has multiple sleeve ribs 62 fixedly attached to its inner sidewall, evenly spaced along the circumference. The sleeve ribs 62 are offset from the outer ribs 53. The inner ribs 43, outer ribs 53, and sleeve ribs 62 are crucial for preventing fluid flow and creating turbulence, increasing the contact area between the fluid and the tube wall and the degree of disturbance, thereby improving heat exchange efficiency. The inner ribs 43, outer ribs 53, and sleeve ribs 62 can have a variety of shapes, such as rectangular, triangular, or trapezoidal. For example, rectangular ribs offer a simple structure and are easy to manufacture. The triangular ribs can better guide the flow direction of the fluid and make the fluid contact with the pipe wall more fully.

[0036] The casing 6 is mounted around the outer periphery of the fluid conversion device 2, forming a third heat exchange chamber 61 between the casing 6 and the fluid conversion device 2. The casing 6 is typically made of a durable metal material, such as carbon steel, to protect the fluid conversion device 2 within from external geological conditions. A certain gap must be maintained between the casing 6 and the fluid conversion device 2 to form an effective third heat exchange chamber 61. The size of this gap should be designed based on actual conditions, ensuring both smooth fluid flow and sufficient heat exchange area.

[0037] An outer reflow port 52 is formed on the wall of the outer tube 5 near the bottom. The outer reflow port 52 connects the third heat exchange chamber 61 and the first heat exchange chamber 41. There are multiple outer reflow ports 52, which are evenly spaced along the circumference and located between two adjacent outer ribs 53. After the fluid undergoes initial heat exchange in the third heat exchange chamber 61, it flows through the outer reflow port 52 into the first heat exchange chamber 41 for further heat exchange. The size and number of the outer reflow ports 52 need to be reasonably designed based on the flow rate and flow velocity of the fluid to ensure that the fluid can flow smoothly from the third heat exchange chamber 61 into the first heat exchange chamber 41.

[0038] An inner return port 42 is formed near the top of the inner tube 4, connecting the second heat exchange chamber 31 with the first heat exchange chamber 41. Multiple inner return ports 42 are evenly spaced along the circumference, located between adjacent inner ribs 43. After heat exchange in the first heat exchange chamber 41, the fluid flows through the inner return ports 42 into the second heat exchange chamber 31, completing the final heat exchange process.

[0039] The implementation principle of the device for improving the heat exchange efficiency of the deep-seated geothermal downhole heat exchange system in Example 1 of the present application is as follows: This device increases the heat exchange path and area of ​​the fluid by providing a first heat exchange chamber 41, a second heat exchange chamber 31, a third heat exchange chamber 61 and a unique fluid conversion device 2. The provision of the inner ribs 43, the outer ribs 53, and the casing ribs 62 blocks the flow of the fluid and forms turbulence when the fluid flows, thereby strengthening the contact and disturbance between the fluid and the pipe wall and improving the heat exchange efficiency. Moreover, the connection and coordination between the various components are reasonable, ensuring that the fluid can flow smoothly between the various heat exchange chambers, achieving efficient heat exchange, and effectively solving the problem of insufficient heat exchange capacity of traditional medium-deep geothermal downhole heat exchange systems due to limited drilling depth, greatly improving the development and utilization efficiency of medium-deep geothermal resources. Compared with traditional devices, under the same geological conditions, the heat exchange efficiency is significantly improved, providing strong support for the efficient development and utilization of medium-deep geothermal resources.

[0040] Example 2 See also Figure 2 and Figure 3This embodiment differs from the above-described embodiments in that the inner ribs 43, outer ribs 53, and sleeve ribs 62 each extend upward in a spiral shape. The spiral ribs enable the fluid to flow along a spiral path, further increasing the fluid's flow path and degree of disturbance. This design allows the fluid to flow in a spiral channel, where it continuously collides and rubs against the tube wall, thereby more fully exchanging heat with the tube wall. In other embodiments, the inner ribs 43, outer ribs 53, and sleeve ribs 62 may each extend circumferentially to form an annular structure.

[0041] In the embodiment of this application, the spiral ribs have a helix angle of 30°-60°. A 30° helix angle results in a smoother flow, suitable for lower flow rates; a 60° helix angle results in greater fluid disturbance, suitable for higher flow rates. By adjusting the helix angle, the heat exchange effect can be optimized according to different practical needs.

[0042] The implementation principle of the device for improving the heat exchange efficiency of the deep-seated geothermal downhole heat exchange system in the second embodiment of the present application is as follows: The spirally extending ribs alter the fluid's flow pattern, increasing its travel and turbulence, ensuring more complete contact between the fluid and the pipe wall, further improving heat transfer efficiency. Under the same operating conditions, compared to circumferentially extending ribs, spiral ribs can improve heat transfer efficiency by a certain percentage, a particularly significant advantage in applications with high flow rates or where higher heat transfer efficiency is required. This design offers a new approach and method for improving the heat transfer efficiency of medium- and deep-level geothermal downhole heat exchange systems, better adapting to varying geological conditions and heat transfer requirements.

[0043] Example 3 The difference between this embodiment and the above embodiment is that: Figure 4 and Figure 5 The inner rib 43 is slidably connected to the outer wall of the inner tube 4 , and the outer rib 53 is slidably connected to the outer wall of the outer tube 5 .

[0044] See also Figure 5 and Figure 6 The outer wall of the outer tube 5 is rotatably connected to an outer ring 54, the outer wall of the inner tube 4 is rotatably connected to an inner ring 44, the outer rib 53 is fixedly connected to the outer ring 54, and the inner rib 43 is fixedly connected to the inner ring 44.

[0045] See also Figure 6 and Figure 7A receiving groove 55 is defined within the top wall of the outer tube 5. This groove 55 extends through the wall of the inner connecting tube 3, connecting the inner connecting tube 3 to the receiving groove 55. A rotating shaft 56 is rotatably connected to the outer tube 5. This shaft 56 is located within the receiving groove 55 and is perpendicular to the inner connecting tube 3. Rotating lobes 57 are fixedly attached to the outer circumference of the rotating shaft 56. Multiple rotating lobes 57 are evenly spaced along the circumference, with those closest to the inner connecting tube 3 extending into the inner connecting tube 3. A control assembly is located within the outer tube 5. When the rotating shaft 56 rotates, the control assembly controls the rotation of the outer ring 54 and the inner ring 44, respectively.

[0046] When fluid flows in the inner connecting tube 3, it drives the rotating blades 57 to rotate, which in turn drives the rotating shaft 56. The rotation of the rotating shaft 56 is transmitted to the outer ring 54 and the inner ring 44 through the control assembly, causing the outer ring 54 and the inner ring 44 to drive the outer ribs 53 and the inner ribs 43 to rotate.

[0047] The control assembly includes an outer gear ring 8 , an inner gear ring 81 , a connecting gear 82 , a connecting shaft 83 , a connecting ball 84 and a connecting wheel 85 .

[0048] The outer gear ring 8 is fixedly connected to the inner circumference of the outer ring 54 and is rotatably connected to the outer tube 5. The inner gear ring 81 is fixedly connected to the inner circumference of the inner ring 44 and is rotatably connected to the inner tube 4. Multiple connecting shafts 83 are rotatably connected to the outer tube 5 and the inner tube 4, respectively. The connecting shafts 83 correspond to the inner gear ring 81 and the outer gear ring 8, respectively. Connecting gears 82 are fixedly connected to the outer circumference of the connecting shafts 83 and correspond one to one. The two connecting gears 82 are rotatably connected to the outer tube 5 and the inner tube 4, respectively, and mesh with the inner gear ring 81 and the outer gear ring 8, respectively.

[0049] See also Figure 7 and Figure 8 Connecting wheels 85 are fixedly connected to the ends of connecting shafts 83 in a one-to-one correspondence. They rotate within the top wall of outer tube 5. Multiple connecting grooves 851 are evenly spaced along the circumference of the outer sidewall of connecting wheel 85. A chute 7 is defined within the top wall of outer tube 5. This chute 7 extends along an elliptical trajectory, encircling both connecting wheels 85 and adjacent to receiving groove 55. Connecting balls 84 slide in chute 7. There are multiple, evenly spaced connecting balls 84. As connecting balls 84 slide past connecting wheels 85, some of them engage in connecting grooves 851, driving connecting wheel 85 to rotate.

[0050] See also Figure 9 and Figure 8The control assembly further includes a transmission shaft 86, a transmission belt 87, and a transmission wheel 88. The transmission shaft 86 is rotatably connected to the inner wall of the top of the outer tube 5. The transmission belt 87 is connected end to end and is sleeved around the rotation shaft 56 and the outer circumference of the transmission shaft 86. The transmission wheel 88 is fixedly connected to the outer circumference of the transmission shaft 86. The outer circumference of the transmission wheel 88 is provided with a plurality of transmission grooves 881 evenly spaced along the circumference. When the connecting balls 84 slide across the transmission wheel 88, some of the connecting balls 84 are locked into the transmission grooves 881.

[0051] When the rotating shaft 56 rotates, the transmission belt 87 transmits power to drive the transmission shaft 86 to rotate, and at this time the transmission wheel 88 drives the connecting ball 84 to slide.

[0052] See also Figure 6 and Figure 7 When the connecting ball 84 slides, the connecting shaft 83 is driven to rotate through the connecting wheel 85, so that the connecting gear 82 enters a rotating state, and then the inner gear ring 81 and the outer gear ring 8 drive the inner ring 44 and the outer ring 54 to rotate respectively.

[0053] The implementation principle of the device for improving the heat exchange efficiency of the deep-seated geothermal downhole heat exchange system in the third embodiment of the present application is as follows: By providing rotatable outer ribs 53, inner ribs 43, and corresponding control components, the flow of the fluid is utilized to drive the rotation shaft 56, thereby causing the outer ribs 53 and inner ribs 43 to rotate. The rotation of the outer ribs 53 and inner ribs 43 increases the relative motion with the fluid, greatly enhancing the degree of fluid disturbance and further improving heat exchange efficiency. In actual operation, this design of rotatable outer ribs 53 and inner ribs 43 can maintain high heat exchange efficiency under different flow rates and flow rates, providing greater adaptability and better response to complex and changing geological conditions and heat exchange requirements, providing a more reliable guarantee for the efficient operation of medium- and deep-layer geothermal underground heat exchange systems.

[0054] Example 4 On the other hand, the present application discloses a heat exchange method for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system, see Figure 11 , including the following steps: S1: Placement of casing 6. Place casing 6 into the geothermal well, and fill fillers between the outer wall of casing 6 and the wall of geothermal well to increase convective heat transfer capacity. When placing casing 6, first select a suitable casing 6, and determine the material and size of casing 6 according to the geological conditions and the specific conditions of the geothermal well. Then use professional drilling equipment to slowly place casing 6 into the geothermal well, ensuring that casing 6 is in a vertical state to avoid tilting that affects the subsequent heat exchange effect. Fill fillers are filled between the outer wall of casing 6 and the wall of geothermal well. The fillers can be made of materials with good thermal conductivity and a certain degree of stability, such as bentonite or quartz sand. The purpose of filling fillers is to fix casing 6 and at the same time improve the heat transfer efficiency between casing 6 and the surrounding geological environment.

[0055] S2: Place the fluid heat exchange device, connect the inner tube 1 to the inner tube connecting tube 3, then place the fluid heat exchange device into the casing 6, and the inner tube 1 is connected to the ground heat pump. When connecting the inner tube 1 to the inner tube connecting tube 3, ensure the firmness and sealing of the connection. The aforementioned threaded connection or welding method can be used. Carefully place the assembled fluid heat exchange device into the casing 6, taking care not to collide with the inner wall of the casing 6 and the casing rib 62. Then connect the inner tube 1 to the ground heat pump. The function of the ground heat pump is to provide power to circulate the fluid in the inner tube 1 and the entire heat exchange system.

[0056] S3: Fluid heat exchange. Inner tube 1 extracts fluid from the geothermal well. At this point, fluid from above the geothermal well flows into the third heat exchange chamber 61 for heat exchange. The fluid passes through the casing ribs 62 and the outer ribs 53, creating turbulent flow. The fluid then flows through the outer return port 52 into the first heat exchange chamber 41. The fluid then passes through the inner ribs 43, creating turbulent flow, and then flows through the inner return port 42 into the second heat exchange chamber 31. Finally, inner tube 1 extracts the heat-exchanged fluid through the inner tube connecting pipe 3. When the ground heat pump is started, inner tube 1 begins extracting fluid from the geothermal well. After entering the third heat exchange chamber 61, the fluid exchanges heat with the walls of the casing 6 and outer tube 5. The presence of the casing ribs 62 and outer ribs 53 creates turbulent flow, improving heat exchange efficiency. The fluid then flows through the outer return port 52 into the first heat exchange chamber 41, continuing heat exchange with the walls of the inner tube 4 and outer tube 5. The inner ribs 43 again create turbulent flow. Finally, the fluid flows into the second heat exchange chamber 31 through the inner reflux port 42 to complete the final heat exchange process. The fluid after heat exchange is extracted by the inner tube 1 through the inner tube connecting tube 3.

[0057] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A device for improving the heat exchange efficiency of a medium-deep geothermal downhole heat exchange system, characterized by: comprising an inner tube (1); A fluid conversion device (2) is arranged at the bottom of the inner tube (1); The fluid conversion device (2) comprises an inner tube connecting tube (3), an inner tube (4) and an outer tube (5); a heat exchange groove (51) is provided in the outer tube (5); the inner tube (4) is arranged on the outer tube (5) and is located in the heat exchange groove (51); a first heat exchange cavity (41) is formed between the inner tube (4) and the outer tube (5); The inner tube connecting pipe (3) is arranged in the inner tube (4), a second heat exchange cavity (31) is formed between the inner tube connecting pipe (3) and the inner tube (4), and the inner tube (1) and the inner tube connecting pipe (3) are connected and coaxially arranged; A sleeve (6) is sleeved on the outer peripheral side of the fluid conversion device (2), and a third heat exchange chamber (61) is formed between the sleeve (6) and the fluid conversion device (2); An outer reflux port (52) is formed on the wall of the outer tube (5) near the bottom, and the outer reflux port (52) is connected to the third heat exchange chamber (61) and the first heat exchange chamber (41); An inner return port (42) is formed on the wall of the inner tube (4) near the top, and the inner return port (42) is connected to the second heat exchange cavity (31) and the first heat exchange cavity (41); The inner tube (4) is provided with an inner convex rib (43) on its outer wall, the outer tube (5) is provided with an outer convex rib (53) on its outer wall, and the sleeve (6) is provided with a sleeve convex rib (62) on its inner circumferential side wall. There are a plurality of the inner convex rib (43), the outer convex rib (53), and the sleeve convex rib (62), respectively, and the ribs are spaced apart along the circumferential direction.

2. The device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system according to claim 1, characterized in that: The inner convex rib (43), the outer convex rib (53), and the sleeve convex rib (62) respectively extend upward in a spiral shape.

3. The device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system according to claim 2, characterized in that: The spiral angles of the inner convex rib (43), the outer convex rib (53), and the sleeve convex rib (62) are 30°-60°.

4. The device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system according to claim 1, characterized in that: The inner convex rib (43), the outer convex rib (53), and the sleeve convex rib (62) respectively extend in the circumferential direction.

5. The device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system according to claim 1 is characterized in that: The horizontal cross-sections of the inner convex rib (43), the outer convex rib (53), and the sleeve convex rib (62) are rectangular, triangular, or trapezoidal.

6. The device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system according to claim 1, characterized in that: The height of the inner rib (43) is 5%-15% of the inner diameter of the inner tube (4); The height of the outer rib (53) is 5%-15% of the inner diameter of the outer tube (5); The height of the sleeve rib (62) is 5%-15% of the inner diameter of the sleeve (6).

7. The device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system according to claim 1, characterized in that: The outer convex rib (53) and the outer wall of the sleeve convex rib (62) are offset from each other.

8. The device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system according to claim 1, characterized in that: The outer wall of the outer tube (5) is rotatably connected to an outer ring (54), the outer wall of the inner tube (4) is rotatably connected to an inner ring (44), the outer rib (53) is connected to the outer ring (54), and the inner rib (43) is connected to the inner ring (44); A receiving groove (55) communicating with the inner tube connecting pipe (3) is provided in the top tube wall of the outer tube (5), the outer tube (5) is rotatably connected to a rotating shaft (56) located in the receiving groove (55), a plurality of rotating blades (57) are provided at intervals along the circumferential direction on the outer peripheral side of the rotating shaft (56), and the rotating blades (57) extend into the inner tube connecting pipe (3); A control component is provided in the outer tube (5), and when the rotating shaft (56) rotates, the control component controls the rotation of the outer ring (54) and the inner ring (44).

9. The device for improving the heat exchange efficiency of a mid-deep geothermal downhole heat exchange system according to claim 8, characterized in that: The control assembly includes an outer gear ring (8), an inner gear ring (81), a connecting gear (82), a connecting shaft (83), a connecting ball (84), a connecting wheel (85), a transmission shaft (86), a transmission belt (87) and a transmission wheel (88); The outer gear ring (8) is arranged on the inner peripheral side wall of the outer ring (54), and the inner gear ring (81) is arranged on the inner peripheral side wall of the inner ring (44); There are multiple connecting shafts (83) which are rotatably connected to the outer tube (5) and the inner tube (4), respectively. The connecting gears (82) are arranged on the outer circumference of the connecting shafts (83) and correspond one to one. The connecting gears (82) are respectively engaged with the inner gear ring (81) and the outer gear ring (8); The connecting wheel (85) is arranged at the end of the connecting shaft (83) and rotates in the top wall of the outer tube (5), and the outer peripheral side wall of the connecting wheel (85) is provided with connecting grooves (851) evenly spaced along the circumferential direction; A sliding groove (7) surrounding the connecting wheel (85) is provided in the top wall of the outer tube (5), and a plurality of connecting balls (84) are evenly slidably connected in the sliding groove (7), and the connecting balls (84) are inserted into the connecting groove (851); The transmission shaft (86) is rotatably connected to the top wall of the outer tube (5), and the transmission belt (87) is connected end to end and is sleeved on the transmission shaft (86) and the outer peripheral side of the rotating shaft (56); The transmission wheel (88) is arranged on the outer peripheral side of the transmission shaft (86), and transmission grooves (881) are evenly spaced along the circumferential direction on the outer peripheral side of the transmission wheel (88), and the connecting ball (84) is inserted into the transmission groove (881).

10. A method for improving the heat exchange efficiency of a medium-deep geothermal downhole heat exchange system, comprising: using the device for improving the heat exchange efficiency of a medium-deep geothermal downhole heat exchange system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: placing the casing (6), placing the casing (6) into the geothermal well, and filling filler between the outer wall of the casing (6) and the wall of the geothermal well; S2: placing the fluid heat exchange device, connecting the inner tube (1) to the inner tube connecting tube (3), then placing the fluid heat exchange device into the casing (6), and the inner tube (1) is connected to the ground heat pump; S3: Fluid heat exchange, the inner tube (1) extracts the fluid in the geothermal well, at this time the fluid above the geothermal well flows into the third heat exchange chamber (61) for heat exchange, the fluid forms turbulence after passing through the casing rib (62) and the outer rib (53), then the fluid flows into the first heat exchange chamber (41) after passing through the outer return port (52), then the fluid forms turbulence after passing through the inner rib (43), and then flows into the second heat exchange chamber (31) through the inner return port (42), and finally the inner tube (1) extracts the fluid after heat exchange through the inner tube connecting tube (3).

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