Devices and methods for improving the heat exchange efficiency of downhole heat exchange systems in medium-deep geothermal wells

Abstract

This application discloses a device and method for improving the heat exchange efficiency of a downhole heat exchange system in medium-deep geothermal wells. It relates to the technical field of heat exchange devices, including an inner tube; a fluid conversion device; the fluid conversion device includes an inner tube connecting pipe, an inner tube, and an outer tube. A heat exchange groove is formed inside the outer tube, and a first heat exchange cavity is formed between the inner tube and the outer tube; a second heat exchange cavity is formed between the inner tube connecting pipe and the inner tube; a third heat exchange cavity is formed between the casing and the fluid conversion device; an outer return port is formed near the bottom of the outer tube wall, connecting 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, connecting the second heat exchange cavity and the first heat exchange cavity; inner ribs are provided on the outer wall of the inner tube, outer ribs are provided on the outer wall of the outer tube, and casing ribs are provided on the inner circumferential sidewall of the casing. This application can improve the heat exchange effect of the heat exchange system.

Description

Technical Field

[0001] This application relates to the technical field of heat exchange devices, and in particular to a device and method for improving the heat exchange efficiency of a downhole heat exchange system in a medium-deep geothermal well. Background Technology

[0002] Medium-deep geothermal well downhole heat exchange systems, as a key method for developing and utilizing geothermal energy, have attracted much attention in recent years. This technology combines downhole heat exchange technology with surface heat pump systems, demonstrating enormous application potential in the energy sector. It is of great significance for improving energy efficiency and environmental protection, helping to optimize my country's energy structure, reduce dependence on fossil fuels, and promote the development of green buildings and low-carbon cities. With the continuous growth of global demand for clean energy, the development and utilization of medium-deep geothermal resources has become a research hotspot, with numerous research teams and enterprises investing significant resources in the research and development and promotion of related technologies.

[0003] In traditional medium-deep geothermal development and utilization, a common approach to addressing the extraction and utilization of geothermal energy is to combine conventional downhole heat exchange systems with surface heat pump devices. Some projects increase the length of downhole heat exchange pipes to enhance the heat exchange area and thus improve heat exchange efficiency; others focus on optimizing the performance of the surface heat pump system, such as improving compressor efficiency and adjusting refrigerant circulation paths, hoping to better convert the low-temperature heat energy extracted from underground into usable high-temperature heat energy; still others attempt to adjust the flow rate of downhole fluids to alter the rate of heat transfer. These methods, to some extent, meet the geothermal energy development needs of certain regions.

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

[0005] To improve the heat exchange efficiency of a heat exchange system, this application provides a device and method for improving the heat exchange efficiency of a downhole heat exchange system in medium-deep geothermal wells.

[0006] In a first aspect, this application provides a device for improving the heat exchange efficiency of a downhole heat exchange system in medium-deep geothermal wells, employing the following technical solution:

[0007] A device for improving the heat exchange efficiency of downhole heat exchange systems in medium-deep geothermal wells, including an inner tube;

[0008] A fluid conversion device is disposed at the bottom of the inner tube;

[0009] The fluid conversion device includes an inner pipe connecting pipe, an inner side pipe and an outer side pipe. A heat exchange groove is opened in the outer side pipe. The inner side pipe is disposed in the outer side pipe and located in the heat exchange groove. A first heat exchange cavity is formed between the inner side pipe and the outer side pipe.

[0010] The inner tube connecting pipe is disposed inside the inner tube, and a second heat exchange chamber is formed between the inner tube connecting pipe and the inner tube. The inner tube and the inner tube connecting pipe are connected and coaxially arranged.

[0011] A sleeve is fitted around the outer periphery of the fluid conversion device, and a third heat exchange chamber is formed between the sleeve and the fluid conversion device;

[0012] An outer return port is formed near the bottom of the outer tube wall, and the outer return port connects the third heat exchange chamber and the first heat exchange chamber;

[0013] An inner reflux port is formed near the top of the inner tube wall, and the inner reflux port connects the second heat exchange chamber and the first heat exchange chamber.

[0014] The inner tube has an inner rib on its outer wall, the outer tube has an outer rib on its outer wall, and the sleeve has a sleeve rib on its inner circumferential side wall. There are multiple inner ribs, outer ribs, and sleeve ribs, which are spaced apart circumferentially.

[0015] By adopting the above technical solution, different heat exchange chambers are constructed using the inner tube, fluid conversion device, and casing, allowing the fluid to flow sequentially within each heat exchange chamber, increasing the water flow length at the bottom of the geothermal well and effectively improving the heat exchange length. Furthermore, by setting circumferentially spaced ribs on each component to create turbulent flow in the fluid, the heat exchange efficiency of the downhole heat exchange system in medium-deep geothermal wells is improved. This helps to solve the problem of insufficient heat exchange capacity in downhole heat exchange systems caused by limited drilling depth, and promotes the efficient development and utilization of medium-deep geothermal resources. At the same time, the fluid conversion device can also be used as a counterweight for the inner tube.

[0016] Optionally, the inner rib, the outer rib, and the sleeve rib extend upward in a spiral shape.

[0017] By adopting the above technical solution, the inner pipe extracts the fluid from the geothermal well, allowing the fluid above the geothermal well to flow into the third heat exchange chamber for heat exchange. The spirally extending upward ribs of the casing and the outer ribs create turbulence in the fluid. After the fluid flows into the first heat exchange chamber through the outer return port, the spirally extending upward ribs of the inner side create turbulence again, enhancing fluid disturbance and increasing the contact area and contact time between the fluid and the walls of each heat exchange chamber, thereby improving the heat exchange efficiency of the downhole heat exchange system in medium-deep geothermal wells.

[0018] Optionally, the helical angle of the inner rib, the outer rib, and the sleeve rib is 30°-60°.

[0019] By adopting the above technical solution, the inner rib, outer rib, and casing rib are made to have a specific spiral angle, which can further enhance the turbulence effect of the fluid flowing through them, thereby improving the heat exchange efficiency of the downhole heat exchange system in medium-deep geothermal wells.

[0020] Optionally, the inner rib, the outer rib, and the sleeve rib extend circumferentially.

[0021] By adopting the above technical solution, the device for improving the heat exchange efficiency of the medium-deep geothermal well downhole heat exchange system, composed of inner tube, fluid conversion device, and casing, increases the contact time and contact area between the fluid and the inner wall of each heat exchange cavity when the fluid flows in each heat exchange cavity, promotes the formation of fluid turbulence, and improves the heat exchange efficiency of the medium-deep geothermal well downhole heat exchange system because the inner ribs, outer ribs, and casing ribs extend circumferentially.

[0022] Optionally, the horizontal cross-section of the inner rib, the outer rib, and the sleeve rib is rectangular, triangular, or trapezoidal.

[0023] By adopting the above technical solution, the horizontal cross-section of the inner rib, outer rib, and casing rib is set as a rectangle, triangle, or trapezoid. This can change the flow state of the fluid flowing through the rib, enhance the turbulence of the fluid, and further promote heat exchange, thereby effectively improving the heat exchange efficiency of the downhole heat exchange system in medium-deep geothermal wells.

[0024] Optionally, the height of the inner rib is 5%-15% of the inner diameter of the inner tube;

[0025] The height of the outer rib is 5%-15% of the inner diameter of the outer tube;

[0026] The height of the sleeve rib is 5%-15% of the inner diameter of the sleeve.

[0027] By adopting the above technical solution, the heights of the inner rib, outer rib, and casing rib are set at 5%-15% of the inner diameter of the inner pipe, the inner diameter of the outer pipe, and the inner diameter of the casing, respectively. This enables the fluid flowing through each heat exchange chamber to form turbulence of appropriate intensity, fully enhancing the degree of fluid disturbance, thereby significantly improving the heat exchange efficiency of the entire medium-deep geothermal well downhole heat exchange system.

[0028] Optionally, the outer rib and the outer wall of the sleeve rib are misaligned.

[0029] By adopting the above technical solution, the combined effect of the outer rib and the casing rib can further form complex turbulence when the fluid flows through the third heat exchange chamber, enhancing fluid disturbance and thus improving the heat exchange efficiency of the downhole heat exchange system in medium-deep geothermal wells.

[0030] Optionally, an outer ring is rotatably connected to the outer wall of the outer tube, an inner ring is rotatably connected to the outer wall of the inner tube, the outer rib is connected to the outer ring, and the inner rib is connected to the inner ring.

[0031] The outer tube has a receiving groove in the top wall that connects to the inner tube connecting tube. The outer tube is rotatably connected to a rotating shaft located in the receiving groove. Multiple rotating blades are arranged circumferentially on the outer periphery of the rotating shaft, and the rotating blades extend into the inner tube connecting tube.

[0032] A control component is provided inside the outer tube. When the rotating shaft rotates, the control component controls the rotation of the outer ring and the inner ring respectively.

[0033] By adopting the above technical solution, when the fluid flows in the inner pipe and impacts the rotating blades, causing the rotating shaft to rotate, the control components can drive the outer and inner rings to rotate, thereby causing the outer and inner ribs to rotate, further enhancing the turbulence effect of the fluid, promoting fluid mixing and heat transfer, and effectively improving heat exchange efficiency.

[0034] Optionally, the control component includes an external gear ring, an internal gear ring, a connecting gear, a connecting shaft, a connecting ball, a connecting wheel, a drive shaft, a drive belt, and a drive wheel;

[0035] The outer toothed ring is disposed on the inner circumferential sidewall of the outer ring, and the inner toothed ring is disposed on the inner circumferential sidewall of the inner ring;

[0036] The connecting shafts are multiple and are rotatably connected to the outer tube and the inner tube respectively. The connecting gears are disposed on the outer circumference of the connecting shafts and correspond one-to-one. The connecting gears mesh with the inner gear ring and the outer gear ring respectively.

[0037] The connecting wheel is disposed at the end of the connecting shaft and rotates within the top wall of the outer tube. The outer peripheral sidewall of the connecting wheel is provided with connecting grooves evenly spaced along the circumferential direction.

[0038] The outer tube has a groove around the connecting wheel inside the top wall of the outer tube. Multiple connecting balls are evenly slidably connected in the groove and are inserted into the groove.

[0039] The drive shaft is rotatably connected to the top wall of the outer tube, and the drive belt is connected end to end and sleeved on the outer periphery of the drive shaft and the rotating shaft.

[0040] The transmission wheel is disposed on the outer periphery of the transmission shaft, and the outer periphery of the transmission wheel is provided with transmission grooves evenly spaced along the circumferential direction, and the connecting ball is inserted into the transmission groove.

[0041] By adopting the above technical solution, the control component can enable the rotating shaft to drive the outer and inner rings to rotate, thereby causing the inner and outer ribs to rotate, further enhancing the fluid turbulence effect and improving the heat exchange efficiency of the downhole heat exchange system in medium-deep geothermal wells.

[0042] Secondly, this application provides a heat exchange method for improving the heat exchange efficiency of a downhole heat exchange system in medium-deep geothermal wells, employing the following technical solution:

[0043] A heat exchange method for improving the heat exchange efficiency of downhole heat exchange systems in medium-deep geothermal wells includes the following steps:

[0044] S1: Casing placement: The casing is placed into the geothermal well, and filler is used to fill the space between the outer wall of the casing and the well wall.

[0045] S2: Place the fluid heat exchange device, connect the inner tube to the inner tube connecting pipe, then place the fluid heat exchange device into the sleeve, and connect the inner tube to the ground heat pump;

[0046] S3: Fluid heat exchange. The inner pipe draws fluid from the geothermal well. At this time, the fluid above the geothermal well flows into the third heat exchange chamber for heat exchange. After passing through the casing ribs and the outer ribs, the fluid forms turbulence. Then, after passing through the outer return port, the fluid flows into the first heat exchange chamber. Then, after passing through the inner ribs, the fluid forms turbulence and flows into the second heat exchange chamber through the inner return port. Finally, the inner pipe draws out the heat-exchanged fluid through the inner pipe connecting pipe.

[0047] By adopting the above technical solution, a heat exchange device composed of casing, inner tube, fluid conversion device and other components can be used to circulate and exchange geothermal fluids. Placing the casing in the geothermal well and filling it with packing material can ensure the stability of the casing. After connecting the inner tube to the inner tube connecting pipe, it is placed in the casing and connected to the surface heat pump to ensure the establishment of a fluid circulation loop. The inner tube extracts geothermal fluid, allowing the fluid to flow in each heat exchange chamber. After passing through the casing ribs, outer ribs and inner ribs, turbulence is formed, which increases the fluid disturbance and mixing degree, enhances the heat transfer effect, and improves the heat exchange efficiency of the downhole heat exchange system in medium and deep geothermal wells. This helps to solve the problem of insufficient heat exchange capacity of downhole heat exchange systems caused by limited drilling depth, and promotes the efficient development and utilization of medium and deep geothermal resources.

[0048] In summary, this application includes at least one of the following beneficial effects:

[0049] 1. By setting up multiple heat exchange chambers and reflux ports, the fluid flows and exchanges heat sequentially in each heat exchange chamber, which improves the heat exchange efficiency of the downhole heat exchange system in medium and deep geothermal wells and solves the problem of insufficient heat exchange capacity caused by the limitation of drilling depth.

[0050] 2. The overall design of the device can effectively extract medium-deep geothermal energy. Combined with a ground heat pump system, it can improve energy utilization efficiency, enhance environmental protection, optimize energy structure, and reduce dependence on fossil fuels. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application;

[0052] Figure 2 This is a schematic diagram of the internal structure of an embodiment of this application;

[0053] Figure 3 This is a schematic diagram of the state when the rib extends circumferentially in the embodiments of this application;

[0054] Figure 4 This is a schematic diagram of the structure when the outer rib is connected to the outer ring in an embodiment of this application;

[0055] Figure 5 This is a schematic diagram of the internal cross-section of an embodiment of this application;

[0056] Figure 6 yes Figure 5 Enlarged schematic diagram of part A;

[0057] Figure 7 yes Figure 5 Enlarged schematic diagram of part B;

[0058] Figure 8 This is a schematic diagram of the internal cross-section of the outer tube in an embodiment of this application;

[0059] Figure 9 This is a schematic diagram of the connection structure between the rotating shaft and the transmission shaft in an embodiment of this application;

[0060] Figure 10 This is a schematic diagram of the connection structure between the transmission wheel and the connecting ball in an embodiment of this application;

[0061] Figure 11 This is a schematic diagram of the steps involved in fluid heat exchange in an embodiment of this application.

[0062] Reference numerals: 1. Inner tube; 2. Fluid conversion device; 3. Inner tube connecting pipe; 31. Second heat exchange chamber; 4. Inner side tube; 41. First heat exchange chamber; 42. Inner side return port; 43. Inner side rib; 44. Inner ring; 5. Outer side tube; 51. Heat exchange groove; 52. Outer side return port; 53. Outer side rib; 54. Outer ring; 55. Receiving groove; 56. Rotating shaft; 57. Rotating blade; 6. Sleeve; 61. Third heat exchange chamber; 62. Sleeve rib; 7. Slide groove; 8. Outer toothed ring; 81. Inner toothed ring; 82. Connecting gear; 83. Connecting shaft; 84. Connecting ball; 85. Connecting wheel; 851. Connecting groove; 86. Drive shaft; 87. Drive belt; 88. Drive wheel; 881. Drive groove. Detailed Implementation

[0063] The following is in conjunction with the appendix Figure 1-11 This application will be described in further detail.

[0064] This application discloses a device for improving the heat exchange efficiency of downhole heat exchange systems in medium-deep geothermal wells.

[0065] Example 1

[0066] See Figure 1 The device for improving the heat exchange efficiency of a medium-deep geothermal well downhole heat exchange system provided in this application includes an inner pipe 1, a fluid conversion device 2, and a casing 6. The fluid conversion device 2 is disposed at the bottom of the inner pipe 1, and the casing 6 is sleeved on the outer periphery of the fluid conversion device 2. This arrangement forms multiple heat exchange chambers, increases the heat exchange area and path, and achieves the effect of improving heat exchange efficiency. This is because multiple heat exchange chambers allow the fluid to exchange heat multiple times in different areas, prolonging the heat exchange time and path, thereby enabling more thorough heat exchange with the surrounding environment.

[0067] See Figure 1 and Figure 2 Specifically, the fluid conversion device 2 includes an inner pipe connecting pipe 3, an inner tube 4, and an outer tube 5. A heat exchange groove 51 is formed inside the outer tube 5. The inner tube 4 is fixedly installed within the outer tube 5 and is located within the heat exchange groove 51. A first heat exchange cavity 41 is formed between the outer wall of the inner tube 4 and the inner circumferential 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.

[0068] The inner tube connecting pipe 3 is disposed inside the inner tube 4 and is fixedly connected to the outer tube 5. The inner tube connecting pipe 3 and the outer tube 5 are coaxially arranged, and the top of the inner tube connecting pipe 3 protrudes outside the outer tube 5. There is a gap between the bottom opening of the inner tube connecting pipe 3 and the bottom wall of the outer tube 5. The inner tube connecting pipe 3 and the inner tube 4 form a second heat exchange chamber 31. The inner tube 1 and the inner tube connecting pipe 3 are coaxially arranged. The inner tube connecting pipe 3 serves to connect the inner tube 1 and the entire fluid conversion device 2. Its material should preferably have good thermal conductivity, such as stainless steel.

[0069] In this embodiment, the inner tube connecting pipe 3 and the inner tube 1 can be connected by a threaded connection. This connection method facilitates installation and disassembly, as well as subsequent maintenance and repair. Simultaneously, the threaded connection ensures a tight seal, reducing the possibility of fluid leakage. Of course, in other embodiments, the inner tube connecting pipe 3 and the inner tube 1 can also be connected by welding. Welding makes the connection more robust, reduces thermal resistance at the connection point, and improves heat exchange efficiency.

[0070] An inner rib 43 is fixedly connected to the outer wall of the inner tube 4. Multiple inner ribs 43 are evenly spaced along the circumference. An outer rib 53 is fixedly connected to the outer wall of the outer tube 5. Multiple outer ribs 53 are evenly spaced along the circumference. A sleeve rib 62 is fixedly connected to the inner circumferential side wall of the sleeve 6. Multiple sleeve ribs 62 are evenly spaced along the circumference, and the sleeve ribs 62 are staggered with the outer ribs 53. The inner ribs 43, outer ribs 53, and sleeve ribs 62 play a significant role in obstructing fluid flow and creating turbulence, increasing the contact area and disturbance between the fluid and the tube wall, thereby improving heat exchange efficiency. The inner ribs 43, outer ribs 53, and sleeve ribs 62 can have various shapes, such as rectangular, triangular, or trapezoidal. Taking a rectangular rib as an example, it has a simple structure and is easy to manufacture. The triangular ribs can better guide the flow direction of the fluid, allowing the fluid to make more full contact with the pipe wall.

[0071] A sleeve 6 is fitted around the outer periphery of the fluid conversion device 2, forming a third heat exchange chamber 61 between the sleeve 6 and the fluid conversion device 2. The sleeve 6 is typically made of a robust and durable metal material, such as carbon steel, to protect the internal fluid conversion device 2 from external geological conditions. A certain gap needs to be maintained between the sleeve 6 and the fluid conversion device 2 to form an effective third heat exchange chamber 61. The size of this gap must be designed according to the actual situation, ensuring both smooth fluid flow and sufficient heat exchange area.

[0072] An outer return port 52 is formed on the outer tube wall near the bottom, connecting the third heat exchange chamber 61 and the first heat exchange chamber 41. Multiple outer return ports 52 are evenly spaced circumferentially, located between adjacent outer ribs 53. After initial heat exchange in the third heat exchange chamber 61, the fluid flows into the first heat exchange chamber 41 through the outer return port 52 for further heat exchange. The size and number of outer return ports 52 need to be rationally designed according to the fluid flow rate and velocity to ensure a smooth flow of fluid from the third heat exchange chamber 61 into the first heat exchange chamber 41.

[0073] An inner return port 42 is formed on the inner wall of the inner tube 4 near the top, connecting the second heat exchange chamber 31 and the first heat exchange chamber 41. Multiple inner return ports 42 are evenly spaced circumferentially, and are located between adjacent inner ribs 43. The fluid that has undergone heat exchange in the first heat exchange chamber 41 flows into the second heat exchange chamber 31 through the inner return port 42, completing the final heat exchange process.

[0074] The implementation principle of the device for improving the heat exchange efficiency of a medium-deep geothermal well downhole heat exchange system in Embodiment 1 of this application is as follows:

[0075] This device, by incorporating 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, increases the heat exchange path and area of ​​the fluid. The inner rib 43, outer rib 53, and casing rib 62 obstruct fluid flow and create turbulence, enhancing the contact and disturbance between the fluid and the pipe wall, thus improving heat exchange efficiency. Furthermore, the rational connection and coordination between components ensures smooth fluid flow between the heat exchange chambers, achieving efficient heat exchange. This effectively solves the problem of insufficient heat exchange capacity in traditional medium-deep geothermal well downhole heat exchange systems due to drilling depth limitations, significantly improving the development and utilization efficiency of medium-deep geothermal resources. Compared to 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.

[0076] Example 2

[0077] See Figure 2 and Figure 3The difference between this embodiment and the previous embodiment is that the inner rib 43, outer rib 53, and sleeve rib 62 extend upwards in a spiral shape. The spiral ribs allow the fluid to flow along a spiral path, further increasing the fluid's flow path and turbulence. This design allows the fluid to flow in a spiral channel, constantly colliding and rubbing against the pipe wall during flow, thus facilitating more thorough heat exchange with the pipe wall. In other embodiments, the inner rib 43, outer rib 53, and sleeve rib 62 may also extend circumferentially and form a ring structure.

[0078] In this embodiment, the helical angle of the spiral ribs is 30°-60°. When the helical angle is 30°, the fluid flow is relatively gentle, suitable for situations with small flow rates; while when the helical angle is 60°, the fluid turbulence is greater, suitable for situations with large flow rates. By adjusting the helical angle, the heat exchange effect can be optimized according to different actual needs.

[0079] The implementation principle of the device for improving the heat exchange efficiency of the downhole heat exchange system in medium-deep geothermal wells in Embodiment 2 of this application is as follows:

[0080] The spirally extending ribs alter the fluid flow pattern, increasing the fluid's travel distance and turbulence, resulting in more thorough contact between the fluid and the pipe wall, thus further improving heat exchange efficiency. Under the same operating conditions, compared to circumferentially extending ribs, spiral ribs can increase heat exchange efficiency by a certain percentage, especially when the flow rate is high or higher heat exchange efficiency is required. This design provides a new approach and method for improving the heat exchange efficiency of downhole heat exchange systems in medium-deep geothermal wells, and can better adapt to different geological conditions and heat exchange requirements.

[0081] Example 3

[0082] The difference between this embodiment and the above embodiments is: See 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.

[0083] See 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.

[0084] See Figure 6 and Figure 7An accommodating groove 55 is formed inside the top wall of the outer tube 5, penetrating the wall of the inner tube connecting tube 3 and thus connecting the accommodating groove 55 to the inner tube connecting tube 3. A rotating shaft 56 is rotatably connected to the outer tube 5, located within the accommodating groove 55 and perpendicular to the inner tube connecting tube 3. Multiple rotating blades 57 are fixedly connected to the outer circumference of the rotating shaft 56, evenly spaced circumferentially, with the blades 57 closest to the inner tube connecting tube 3 extending into it. A control component is installed inside the outer tube 5; when the rotating shaft 56 rotates, the control component controls the rotation of both the outer ring 54 and the inner ring 44.

[0085] When the fluid flows within the inner pipe connecting pipe 3, it drives the rotating blade 57 to rotate, which in turn causes the rotating shaft 56 to rotate. The rotation of the rotating shaft 56 is transmitted to the outer ring 54 and the inner ring 44 through the control component, causing the outer ring 54 and the inner ring 44 to drive the outer rib 53 and the inner rib 43 to rotate.

[0086] The control assembly includes an external gear ring 8, an internal gear ring 81, a connecting gear 82, a connecting shaft 83, a connecting ball 84, and a connecting wheel 85.

[0087] An external gear ring 8 is fixedly connected to the inner circumferential side wall of an outer ring 54 and rotatably connected to an outer tube 5. An internal gear ring 81 is fixedly connected to the inner circumferential side wall of an inner ring 44 and rotatably connected to an inner tube 4. Multiple connecting shafts 83 are rotatably connected to the outer tube 5 and the inner tube 4, respectively, and each connecting shaft 83 corresponds to both the internal gear ring 81 and the external gear ring 8. Connecting gears 82 are fixedly connected to the outer circumferential side of the connecting shafts 83 and correspond one-to-one. Two connecting gears 82 are rotatably connected to the outer tube 5 and the inner tube 4, respectively, and each connecting gear 82 meshes with both the internal gear ring 81 and the external gear ring 8.

[0088] See Figure 7 and Figure 8 Connecting wheels 85 are fixedly connected to the ends of connecting shafts 83 and correspond one-to-one. Connecting wheels 85 rotate within the top wall of the outer tube 5. Multiple connecting grooves 851 are evenly spaced circumferentially on the outer sidewall of the connecting wheels 85. A sliding groove 7 is formed within the top wall of the outer tube 5, extending along an elliptical trajectory. The sliding groove 7 surrounds the two connecting wheels 85 and is adjacent to the receiving groove 55. Connecting balls 84 are slidably connected within the sliding groove 7. Multiple connecting balls 84 are evenly distributed. When the connecting balls 84 slide past the connecting wheels 85, some of the connecting balls 84 are engaged in the connecting grooves 851, pushing the connecting wheels 85 to rotate.

[0089] See Figure 9 and Figure 8The control assembly also includes a drive shaft 86, a drive belt 87, and a drive wheel 88. The drive shaft 86 is rotatably connected to the top wall of the outer tube 5. The drive belt 87 is connected end to end and sleeved on the outer periphery of the rotating shaft 56 and the drive shaft 86. The drive wheel 88 is fixedly connected to the outer periphery of the drive shaft 86. Multiple drive grooves 881 are evenly spaced along the circumference of the outer periphery of the drive wheel 88. When the connecting ball 84 slides past the drive wheel 88, some of the connecting ball 84 is engaged in the drive groove 881.

[0090] When the rotating shaft 56 rotates, the transmission belt 87 transmits power, causing the transmission shaft 86 to rotate. At this time, the transmission wheel 88 causes the connecting ball 84 to slide.

[0091] See Figure 6 and Figure 7 When the connecting ball 84 slides, it drives the connecting shaft 83 to rotate through the connecting wheel 85, causing the connecting gear 82 to enter a rotating state, which in turn causes the internal gear ring 81 and the external gear ring 8 to drive the inner ring 44 and the outer ring 54 to rotate respectively.

[0092] The implementation principle of the device for improving the heat exchange efficiency of the downhole heat exchange system in medium-deep geothermal wells in Embodiment 3 of this application is as follows:

[0093] By incorporating rotatable outer ribs 53 and inner ribs 43, along with corresponding control components, the flow of fluid drives the rotating shaft 56 to rotate, thereby causing the outer ribs 53 and inner ribs 43 to rotate. This rotation increases the relative motion between the outer ribs 53 and inner ribs 43 and the fluid, significantly enhancing fluid turbulence and further improving heat exchange efficiency. In actual operation, this rotatable design of the outer ribs 53 and inner ribs 43 maintains high heat exchange efficiency under varying flow rates and velocities, demonstrating greater adaptability and better handling of complex and variable geological conditions and heat exchange requirements. This provides a more reliable guarantee for the efficient operation of downhole heat exchange systems in medium-deep geothermal wells.

[0094] Example 4

[0095] On the other hand, this application discloses a heat exchange method for improving the heat exchange efficiency of downhole heat exchange systems in medium-deep geothermal wells, see [link to relevant documentation]. Figure 11 This includes the following steps:

[0096] S1: Casing 6 Placement. Casing 6 is placed into the geothermal well, and filler is used between the outer wall of casing 6 and the well wall to increase convective heat transfer capacity. When placing casing 6, a suitable casing 6 must first be selected, determining its material and size based on geological conditions and the specific characteristics of the geothermal well. Then, using specialized drilling equipment, casing 6 is slowly lowered into the geothermal well, ensuring it is vertical to avoid tilting and affecting subsequent heat exchange. Filler is then used between the outer wall of casing 6 and the well wall. The filler can be a material with good thermal conductivity and stability, such as bentonite or quartz sand. The purpose of filling is to fix casing 6 and simultaneously improve the heat transfer efficiency between casing 6 and the surrounding geological environment.

[0097] S2: Place the fluid heat exchanger. Connect the inner tube 1 to the inner tube connecting pipe 3. Then, place the fluid heat exchanger into the sleeve 6. Connect the inner tube 1 to the ground heat pump. When connecting the inner tube 1 to the inner tube connecting pipe 3, ensure the connection is secure and airtight. Threaded connections or welding methods mentioned earlier can be used. Carefully place the assembled fluid heat exchanger into the sleeve 6, taking care not to bump the inner wall of the sleeve 6 or the sleeve ribs 62. Then connect the inner tube 1 to the ground heat pump. The ground heat pump provides power to circulate the fluid in the inner tube 1 and throughout the entire heat exchange system.

[0098] S3: Fluid heat exchange. Inner pipe 1 draws fluid from the geothermal well. At this time, the fluid above the geothermal well flows into the third heat exchange chamber 61 for heat exchange. After passing through the sleeve rib 62 and the outer rib 53, the fluid forms turbulence. Then, the fluid flows into the first heat exchange chamber 41 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. Finally, inner pipe 1 draws out the heat-exchanged fluid through inner pipe connecting pipe 3. When the ground heat pump starts, inner pipe 1 begins to draw fluid from the geothermal well. After entering the third heat exchange chamber 61, the fluid exchanges heat with the walls of the sleeve 6 and the outer pipe 5. Due to the presence of the sleeve rib 62 and the outer rib 53, the fluid forms turbulence, improving the heat exchange efficiency. Then, the fluid flows into the first heat exchange chamber 41 through the outer return port 52, continuing to exchange heat with the walls of the inner pipe 4 and the outer pipe 5. The inner rib 43 again causes the fluid to form turbulence. Finally, the fluid flows into the second heat exchange chamber 31 through the inner return port 42, completing the final heat exchange process. The heat-exchanged fluid is then extracted by the inner tube 1 through the inner tube connecting pipe 3.

[0099] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A device for improving the heat exchange efficiency of downhole heat exchange systems in medium-deep geothermal wells, characterized in that: Including the inner tube (1); A fluid conversion device (2) is disposed at the bottom of the inner tube (1); The fluid conversion device (2) includes an inner pipe connecting pipe (3), an inner pipe (4) and an outer pipe (5). A heat exchange groove (51) is opened in the outer pipe (5). The inner pipe (4) is disposed in the outer pipe (5) and located in the heat exchange groove (51). A first heat exchange chamber (41) is formed between the inner pipe (4) and the outer pipe (5). The inner tube connecting pipe (3) is disposed inside the inner tube (4), and a second heat exchange chamber (31) is formed between the inner tube connecting pipe (3) and the inner tube (4). The inner tube (1) is connected to the inner tube connecting pipe (3) and is coaxially disposed. A sleeve (6) is fitted on the outer periphery 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). The outer tube (5) has an outer return port (52) formed near the bottom of the tube wall. The outer return port (52) connects the third heat exchange chamber (61) and the first heat exchange chamber (41). The inner tube (4) has an inner reflux port (42) formed near the top of the tube wall. The inner reflux port (42) connects the second heat exchange chamber (31) and the first heat exchange chamber (41). The inner tube (4) has an inner rib (43) on its outer wall, the outer tube (5) has an outer rib (53) on its outer wall, and the sleeve (6) has a sleeve rib (62) on its inner circumferential side wall. There are multiple inner ribs (43), outer ribs (53), and sleeve ribs (62) that are spaced apart along the circumferential direction. 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). The outer tube (5) has a receiving groove (55) in the top wall that connects to the inner tube connecting tube (3). The outer tube (5) is rotatably connected to a rotating shaft (56) located in the receiving groove (55). Multiple rotating blades (57) are arranged circumferentially on the outer periphery of the rotating shaft (56). The rotating blades (57) extend into the inner tube connecting tube (3). A control component is provided inside the outer tube (5). When the rotating shaft (56) rotates, the control component controls the outer ring (54) and the inner ring (44) to rotate respectively.

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

3. The device for improving the heat exchange efficiency of a medium-deep geothermal well 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).

4. The device for improving the heat exchange efficiency of a medium-deep geothermal well downhole heat exchange system according to claim 1, characterized in that: The outer rib (53) and the outer wall of the sleeve rib (62) are misaligned.

5. The device for improving the heat exchange efficiency of a medium-deep geothermal well downhole heat exchange system according to claim 1, characterized in that: The control assembly includes an external gear ring (8), an internal 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 toothed ring (8) is disposed on the inner circumferential sidewall of the outer ring (54), and the inner toothed ring (81) is disposed on the inner circumferential sidewall of the inner ring (44); The connecting shafts (83) are multiple and are rotatably connected to the outer tube (5) and the inner tube (4) respectively. The connecting gears (82) are disposed on the outer circumference of the connecting shafts (83) and correspond one to one. The connecting gears (82) mesh with the inner gear ring (81) and the outer gear ring (8) respectively. The connecting wheel (85) is located at the end of the connecting shaft (83) and rotates within the top wall of the outer tube (5). The outer peripheral sidewall of the connecting wheel (85) is provided with connecting grooves (851) evenly spaced along the circumferential direction. The outer tube (5) has a groove (7) inside the top tube wall that surrounds the connecting wheel (85). Multiple connecting balls (84) are evenly connected in the groove (7), and the connecting balls (84) are inserted into the connecting groove (851). The drive shaft (86) is rotatably connected to the top wall of the outer tube (5), and the drive belt (87) is connected end to end and sleeved on the outer periphery of the drive shaft (86) and the rotating shaft (56). The transmission wheel (88) is disposed on the outer periphery of the transmission shaft (86), and the outer periphery of the transmission wheel (88) is provided with transmission grooves (881) evenly spaced along the circumference, and the connecting ball (84) is inserted into the transmission groove (881).

6. A heat exchange method for improving the heat exchange efficiency of a downhole heat exchange system in a medium-deep geothermal well, comprising the apparatus for improving the heat exchange efficiency of a downhole heat exchange system in a medium-deep geothermal well as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Casing (6) placement: The casing (6) is placed into the geothermal well, and filler is placed between the outer wall of the casing (6) and the well wall of the geothermal well. S2: Place the fluid heat exchange device, connect the inner tube (1) to the inner tube connecting pipe (3), then put the fluid heat exchange device into the sleeve (6), and connect the inner tube (1) to the ground heat pump. S3: Fluid heat exchange, the inner tube (1) draws out 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) draws out the heat-exchanged fluid through the inner tube connecting pipe (3).

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