Bionic vein fractal medium-deep layer buried pipe heat exchanger and heat exchange system
By adopting a bionic leaf vein fractal structure in the buried pipe heat exchanger, the density and angle of branch pipes gradually increase, and the gradient release of multi-stage heat exchange paths is achieved, which solves the problem of uneven heat distribution of existing buried pipe heat exchangers, and improves the heat exchange efficiency and system stability.
Patent Information
- Application Number
- CN202510894624.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-08-15
AI Technical Summary
The existing buried pipe heat exchangers fail to design targeted heat exchange partitions based on the thermal conductivity and heat capacity characteristics of different depths of the soil, resulting in concentrated heat distribution, strong thermal disturbances on the upper layer and low heat exchange efficiency on the lower layer. After long-term operation, it is easy to form a thermal saturation zone, affecting the system's heat exchange capacity and the COP of the ground source heat pump.
A bionic leaf vein fractal medium-deep buried pipe heat exchanger is used. By layering multiple branch pipes on the main pipe, the density and angle of branch pipes gradually increase from top to bottom. According to the fractal structure of plant leaf veins, the gradient release of multi-stage heat exchange paths is achieved, and the heat exchange coupling ability at different depths is enhanced.
Significantly improve heat exchange efficiency, delay the trend of ground source heat field saturation, improve the energy efficiency and long-term operation stability of ground source heat pump system, optimize heat flow distribution, reduce flow resistance, and enhance the heat utilization efficiency of deep soil.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of heat exchanger structures, and in particular relates to a bionic leaf vein fractal medium-deep underground pipe heat exchanger and a heat exchange system. Background Art
[0002] A heat exchanger is a device that transfers part of the heat of a hot fluid to a cold fluid, also known as a heat exchanger. A buried pipe heat exchanger is one of them. It is usually composed of heat exchange pipes buried underground, connecting pipes, collectors, circulating pumps, heat exchange media, insulation layers, backfill soil, etc.
[0003] The buried pipe heat exchanger utilizes the temperature stability of the soil to exchange heat with the soil through the circulating medium in the pipe to achieve heat transfer or storage. In summer, the circulating water releases the heat absorbed by the refrigeration unit to the soil; in winter, it absorbs heat from the soil and transfers the heat to the room through the heat pump unit.
[0004] Most existing buried pipe structures fail to carry out targeted heat exchange zoning design based on the thermal conductivity and heat capacity characteristics of the soil at different depths. This results in concentrated heat distribution in the heat exchange tubes of the buried pipe heat exchanger, strong thermal disturbance in the upper layer and low heat exchange efficiency in the lower layer. After long-term operation, a thermal saturation zone is easily formed, thereby affecting the system's heat exchange capacity and the COP of the ground source heat pump. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a bionic leaf vein fractal medium-deep buried pipe heat exchanger and heat exchange system to overcome the technical problem of low heat exchange efficiency of the existing buried pipe heat exchanger.
[0006] The present invention adopts the following technical solutions: A bionic leaf vein fractal medium-deep underground heat exchanger, comprising a heat exchange tube, wherein the heat exchange tube comprises a main tube and a plurality of branch tubes connected to the main tube, wherein the plurality of branch tubes are arranged in layers in a vertical direction along the main tube; The branch pipes are arranged vertically along the main pipe with a density gradually increasing from top to bottom; One end of each of the branch pipes is connected to the main pipe, and the other end extends radially outward.
[0007] Furthermore, the lengths of the plurality of branch pipes gradually increase from top to bottom along the vertical direction of the main pipe.
[0008] Furthermore, the length calculation formula of the branch pipe is:
[0009] Where L0 is the initial length at the surface, α is the length adjustment coefficient, L(z) is the branch length at depth z, G(z) is the geothermal gradient at depth z, and G0 is the reference geothermal gradient (0.025°C / m).
[0010] Furthermore, the value range of L0 is 1~2 m, and the value range of α is 5~10 mm / m.
[0011] Furthermore, the diameters of the plurality of branch pipes gradually increase from top to bottom along the vertical direction of the main pipe.
[0012] Furthermore, the angles between the plurality of branch pipes and the main pipe gradually increase from top to bottom along the vertical direction of the main pipe.
[0013] Furthermore, the angle between the branch pipe and the main pipe is calculated as follows:
[0014] Where θ0 is the initial angle at the surface, β is the angle adjustment coefficient, θ(z) is the branch angle at depth z, G(z) is the geothermal gradient at depth z, is the reference geothermal gradient (0.025℃ / m).
[0015] Furthermore, the value range of θ0 is 10~20°, and the value range of β is 0.02~0.04° / m.
[0016] In a second aspect, a heat exchange system is provided, including a bionic leaf vein fractal medium-deep buried pipe heat exchanger.
[0017] Furthermore, the heat exchange system at least includes a ground source heat pump system.
[0018] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention provides a bionic leaf vein fractal medium-deep buried pipe heat exchanger, which includes a main pipe of the heat exchanger and multiple branch pipes connected to the main pipe. The branch pipes are arranged in layers on the main pipe and extend radially outward. The density of the branch pipes gradually increases from top to bottom, and the distribution form imitates the fractal structure of plant leaf veins. Based on the leaf vein fractal principle, the present invention arranges multi-level heat exchange paths in layers and zones, so that the heat exchange pipe structure has variable density and adaptive distribution capabilities in both vertical and horizontal dimensions, realizing the gradient release of heat load in multiple depth spaces underground. The layout density of the branch pipes gradually increases from top to bottom, enhancing the heat exchange coupling capacity of different depths of the stratum, thereby significantly improving the heat exchange efficiency, delaying the saturation trend of the ground source heat field, and improving the energy efficiency and long-term operation stability of the ground source heat pump system.
[0019] Preferably, the length of the branch pipe gradually increases from top to bottom along the vertical direction of the main pipe. By lengthening the heat exchange path of the deep branch pipe, its coverage area in the deep soil is expanded, the heat energy extraction depth and thermal field recovery capacity of the low-disturbance area are improved, and the heat utilization efficiency of the deep soil is enhanced.
[0020] Preferably, the diameter of the branch pipe gradually increases from top to bottom in the vertical direction of the main pipe, so that the deep branch pipe has a larger flow cross-section, reducing the flow resistance during long-distance transmission, ensuring the flow rate and heat transfer intensity of the heat medium fluid in the deep branch, and improving the system operation efficiency.
[0021] Preferably, the angle between the branch pipe and the main pipe gradually increases from top to bottom along the vertical direction of the main pipe, which not only optimizes the spatial distribution between the branch pipes and avoids overlapping interference of heat flow, but also enhances the response ability of each heat exchange branch to the thermal properties of different soil layers, thereby improving the efficiency of the entire heat exchange system and the uniformity of geothermal field utilization.
[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 This is a schematic structural diagram of a bionic leaf vein fractal medium-deep underground heat exchanger according to the present invention; Figure 2 This is a structural diagram of the changes in the length, diameter and angle of the branch pipes of the buried pipe heat exchanger.
[0024] Among them: 1. Main pipeline; 2. Branch pipeline. DETAILED DESCRIPTION
[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.
[0026] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "one side," "one end," and "one side" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, in the description of the present invention, unless otherwise specified, "a plurality" means two or more.
[0027] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.
[0028] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.
[0029] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.
[0030] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
[0031] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.
[0032] The present invention provides a bionic leaf vein fractal deep underground heat exchanger, such as Figure 1 As shown, the heat exchange tube includes a main tube 1 and multiple branch tubes 2, wherein one end of the multiple branch tubes 2 is connected to the main tube 1 and the other end extends outward away from the main tube 1. Along the vertical direction of the main tube 1, the branch tubes 2 are arranged in layers and the density gradually increases from top to bottom.
[0033] The heat exchange tube is the core component of the buried pipe heat exchanger. To address the problems of existing buried pipe heat exchangers, such as weak soil thermal recovery ability, low heat transfer efficiency, and high energy consumption, caused by the mismatch between the single structure and the thermal characteristics of the formation, the present invention proposes a medium-deep buried pipe heat exchanger with a bionic leaf vein fractal structure. This structure is based on the principle of fractal expansion of plant leaf veins and combines the vertical thermal gradient variation characteristics of the formation. Through the pipeline configuration strategy of "deep burial of the trunk, layered branches, and dense ends", it improves the heat exchange intensity while reducing the overall flow resistance, ensuring the energy efficiency and stability of the system in long-term operation.
[0034] In an optional embodiment, a bionic leaf vein fractal medium-deep buried pipe heat exchanger is provided, comprising a main pipe 1 and a plurality of branch pipes 2. The main pipe 1 extends downward from the surface to a target heat exchange depth. The plurality of branch pipes 2 are arranged vertically along the main pipe 1 in a layered manner. The branch pipes 2 extend radially outward, and their distribution pattern imitates the fractal structure of plant leaf veins. Based on the principle of leaf vein fractal, multi-level heat exchange paths are arranged in layers and zones, so that the heat exchange tube structure has variable density and adaptive distribution capabilities in both vertical and horizontal dimensions, realizing the gradient release of heat load in multiple depth spaces underground. The layout density of branch pipes gradually increases from top to bottom, enhancing the heat exchange coupling capacity of different depths of the stratum, thereby significantly improving the heat exchange efficiency, delaying the saturation trend of the ground source thermal field, and improving the energy efficiency and long-term operation stability of the ground source heat pump system.
[0035] Alternatively, in another embodiment, Figure 2 As shown, a bionic leaf vein fractal medium-deep buried pipe heat exchanger is provided. Unlike the buried pipe heat exchanger structure mentioned above, the length and diameter of the branch pipe 2 increase step by step with the increase of the buried depth of the heat exchange pipe. The improvement of the above structure not only optimizes the fluid transport capacity of each branch in the heat exchange network, but also enhances the deep heat extraction capacity, improves the overall heat exchange efficiency and operation stability of the system, and the incremental design of the branch pipe 2 is combined with the underground thermal field distribution characteristics and thermal physical property changes, so that the heat exchanger responds to the geothermal gradient more efficiently, thereby achieving the geothermal development goals of layered regulation, zoned utilization, and cascade release.
[0036] Specifically, the diameter of the branch pipe 2 increases layer by layer as the buried depth of the main pipe 1 increases, so that the deep branch pipe 2 has a larger flow cross-section, reducing the flow resistance during long-distance transmission, ensuring the flow rate and heat transfer intensity of the heat medium fluid in the deep branch, and improving the system operation efficiency; Similarly, the length of the branch pipe 2 increases layer by layer from top to bottom. By lengthening the heat exchange path of the deep branch pipe 2, its coverage area in the deep soil is expanded, the heat energy extraction depth and thermal field recovery capacity of the low-disturbance area are increased, and the heat utilization efficiency of the deep soil is enhanced. The length L of the branch pipe 2 of the buried pipe in the vertical direction increases with the depth z and the geothermal gradient G(z). It is preferably arranged using a function control relationship in the form of a function:
[0037] Where L0 is the initial length at the surface, α is the length adjustment coefficient, L(z) is the length of the branch pipe at depth z, G(z) is the geothermal gradient at depth z, and G0 is the reference geothermal gradient (0.025°C / m); The function can be adjusted according to the geological thermal resistance distribution, heat exchange intensity requirements and construction capacity. The optimal range of L0 is 1~2 m and α is 5~10 mm / m.
[0038] Therefore, the incremental design of the length and diameter of the branch pipe 2, combined with the characteristics of mid-deep geothermal energy, can achieve cascade utilization of geothermal resources.
[0039] Alternatively, in another embodiment, Figure 2 As shown, a bionic leaf vein fractal medium-deep underground heat exchanger is provided. Unlike the above-mentioned underground heat exchanger structure, the angle between the branch pipe 2 and the main pipe 1 is arranged from top to bottom along the vertical direction of the main pipe 1. That is, a small angle is used in the upper area of the main pipe 1 for compact layout, while a large angle is used in the lower area for divergent layout, thereby reducing the heat exchange interference area and expanding the heat exchange coverage. The angle θ of the branch pipe 2 of the buried pipe in the vertical direction increases with the depth z and the geothermal gradient G(z). It is preferably arranged using a function control relationship in the form of a function:
[0040] Where θ0 is the initial angle at the surface, β is the angle adjustment coefficient, θ(z) is the angle of the branch pipe at depth z, G(z) is the geothermal gradient at depth z, The reference geothermal gradient is 0.025°C / m. The range of θ0 is 10-20°, and β is 0.02-0.04° / m.
[0041] The gradual increase in the angle can effectively guide the deep heat medium fluid to more fully expand the heat transfer path to the lateral soil, improve the problem of highly concentrated thermal disturbance caused by vertical pipe layout, and thus increase the effective heat exchange area per unit depth of the formation.
[0042] In the above technical solution, the angle design is combined with the bionic fractal pipe layout to construct a multi-level distributed mesh heat exchange structure similar to the "blade-petiole-trunk" type, thereby enhancing the flow uniformity of the heat medium fluid in the pipeline network, reducing the probability of the formation of local overheating or overcooling areas, and improving the long-term heat exchange stability of the system.
[0043] The angle between the branch pipes and the main pipe increases layer by layer. By controlling the angle between the branch pipes 2 and the main pipe 1 at different depths and laying them out in order from smallest to largest, this not only optimizes the spatial distribution between the branch pipes 2 and avoids overlapping interference in heat flow, but also enhances the response of each heat exchange branch to the thermal properties of different soil layers, thereby improving the efficiency of the entire heat exchange system and the uniformity of geothermal field utilization.
[0044] The present invention relates to a bionic leaf vein fractal medium-deep underground pipe heat exchanger mainly suitable for scenarios with high requirements for heat exchange efficiency, thermal uniformity and system stability, such as large regional energy stations, industrial waste heat recovery systems, ultra-low energy consumption buildings and green parks with high-density cooling and heating loads. Its bionic leaf vein fractal structure significantly improves heat transfer uniformity and reduces flow resistance through topological optimization design. It is particularly suitable for areas with complex geological conditions or significant stratum temperature gradients. By simulating the fractal structure of leaf veins in nature and optimizing the fluid channel layout, it significantly improves heat exchange efficiency and thermal uniformity. Its core innovation lies in combining bionics with topological optimization technology to reduce thermal resistance and pressure loss while adapting to complex geological conditions. It can effectively alleviate the problem of thermal uniformity in shallow soil and improve the utilization efficiency of deep geothermal energy.
[0045] The present invention also protects a heat exchange system, wherein the heat exchange system includes the bionic leaf vein fractal medium-deep underground pipe heat exchanger mentioned in the present invention; Specifically, the heat exchange system includes at least a ground source heat pump system, and in addition to the ground source heat pump system, it also includes a geothermal heating system, a geothermal cooling system and an industrial waste heat recovery system.
[0046] The above content is only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.
Claims
1. A bionic leaf vein fractal medium-deep underground heat exchanger, characterized in that: The heat exchange tube comprises a main tube (1) and a plurality of branch tubes (2) connected to the main tube (1), wherein the plurality of branch tubes (2) are arranged in layers in a vertical direction along the main tube (1); The plurality of branch pipes (2) are arranged vertically along the main pipe (1) with a density gradually increasing from top to bottom; One end of the plurality of branch pipes (2) is connected to the main pipe (1), and the other end extends radially outward.
2. The bionic leaf vein fractal medium-deep underground heat exchanger according to claim 1 is characterized in that: The lengths of the plurality of branch pipes (2) gradually increase from top to bottom along the vertical direction of the main pipe (1).
3. The bionic leaf vein fractal medium-deep underground heat exchanger according to claim 2, characterized in that: The length calculation formula of the branch pipe (2) is: Where L0 is the initial length at the surface, α is the length adjustment coefficient, L(z) is the length of the branch pipe at depth z, G(z) is the geothermal gradient at depth z, and G0 is the reference geothermal gradient (0.025°C / m).
4. The bionic leaf vein fractal medium-deep underground heat exchanger according to claim 3 is characterized in that: The L0 value range is 1~2 m, and the α value range is 5~10 mm / m.
5. The bionic leaf vein fractal medium-deep underground heat exchanger according to claim 1, characterized in that: The diameters of the plurality of branch pipes (2) gradually increase from top to bottom along the vertical direction of the main pipe (1).
6. The bionic leaf vein fractal medium-deep underground heat exchanger according to claim 1, characterized in that: The angles between the plurality of branch pipes (2) and the main pipe (1) gradually increase from top to bottom along the vertical direction of the main pipe (1).
7. The bionic leaf vein fractal medium-deep underground heat exchanger according to claim 6, characterized in that: The angle calculation formula between the branch pipe (2) and the main pipe (1) is: Where θ0 is the initial angle at the surface, β is the angle adjustment coefficient, θ(z) is the angle of the branch pipe at depth z, G(z) is the geothermal gradient at depth z, is the reference geothermal gradient (0.025℃ / m).
8. The bionic leaf vein fractal medium-deep underground heat exchanger according to claim 7, characterized in that: The value range of θ0 is 10~20°, and the value range of β is 0.02~0.04° / m.
9. A heat exchange system, characterized in that: The invention comprises the bionic leaf vein fractal medium-deep buried pipe heat exchanger as described in any one of claims 1 to 8.
10. A heat exchange system according to claim 9, characterized in that: The heat exchange system at least includes a ground source heat pump system.