Hydrothermal self-driven cycle experimental device and experimental method

Abstract

A hydrothermal self-driven circulation experimental device and experimental method belong to the field of thermal performance testing and analysis technology, including: a fracture simulation module, the fracture simulation module has a flat fracture structure, including a first vertical plate and a second vertical plate arranged opposite to each other, the spacing distance between the first vertical plate and the second vertical plate is adjustable, the first vertical plate and the second vertical plate are both made according to the fracture curve, and the surface shapes of the two facing each other are consistent with the fracture curve; a heat exchange module, the heat exchange module is arranged at the lateral end of the fracture simulation module, and a heat absorption medium flowing in the vertical direction is arranged in the heat exchange module, and the heat absorption medium is used to exchange heat with the fluid in the flat fracture; a heating module, the heating module is arranged at the bottom of one side of the fracture simulation module, the spacing distance between the heating module and the heat exchange module is adjustable, and the heating module is used to simulate an underground heat source to heat the fluid in the flat fracture; a detection and control module, the detection and control module is used to determine the heat exchange efficiency of the heat exchange module.

Description

Technical Field

[0001] The present application belongs to the technical field of thermal performance testing and analysis, and specifically relates to a hydrothermal self-driven cycle experimental device and experimental method. Background Art

[0002] In the fields of earth science and energy engineering, geothermal resources, as a clean and renewable energy source, are gaining increasing attention for their development and utilization. The flow and heat exchange of underground hydrothermal fluids within fractures are the core foundation of geothermal resource development. A thorough analysis of the hydrothermal self-driven circulation mechanisms within fractures plays a key role in improving geothermal resource extraction efficiency and optimizing extraction strategies.

[0003] However, the geothermal heat exchange model experimental devices currently available on the market are inadequate for conducting thermosiphon-type heat storage self-driven circulation heat exchange experiments. They are unable to simulate the self-driven flow and heat exchange of underground hydrothermal fluids within fractures under the thermosiphon effect. Consequently, researchers have difficulty exploring the specific manifestations and inherent laws of the hydrothermal self-driven circulation mechanism under different fracture characteristics (including fracture aperture, fracture roughness, and fluid circulation paths within the fracture channels). This situation has significantly limited basic research and technological innovation in the field of geothermal resource development. There is an urgent need to develop new experimental devices to overcome existing technical bottlenecks and provide theoretical support and technical guarantees for the efficient development of geothermal resources. Summary of the Invention

[0004] In view of this, the present application provides a hydrothermal self-driven circulation experimental device and experimental method, the main purpose of which is to study the fluid self-driven circulation heat transfer mechanism under different fracture characteristic conditions.

[0005] To achieve the above objectives, this application mainly provides the following technical solutions:

[0006] In one aspect of the present application, a hydrothermal self-driven cycle experimental device is provided, comprising:

[0007] A fracture simulation module having a flat fracture structure, comprising a first vertical plate and a second vertical plate arranged opposite each other, wherein the spacing between the first vertical plate and the second vertical plate is adjustable, and the first vertical plate and the second vertical plate are both manufactured according to the fracture curve, and the shapes of the surfaces facing each other are consistent with the fracture curve;

[0008] a heat exchange module, the heat exchange module being arranged at a lateral end of the fracture simulation module, wherein a heat absorbing medium flowing in a vertical direction is arranged in the heat exchange module, and the heat absorbing medium is used to exchange heat with the fluid in the fracture of the plate;

[0009] A heating module, the heating module is arranged at the bottom of one side of the fracture simulation module, the spacing between the heating module and the heat exchange module is adjustable, and the heating module is used to simulate an underground heat source to heat the fluid in the flat plate fracture;

[0010] A detection and control module is used to determine the heat exchange efficiency of the heat exchange module.

[0011] Optionally, the inspection and control module includes:

[0012] a first temperature monitoring module, which is disposed at the inlet of the heat exchange module and is used to monitor the temperature of the heat absorbing medium when it flows into the heat exchange module;

[0013] The second temperature monitoring module is arranged at the outlet of the heat exchange module and is used to monitor the temperature of the heat absorbing medium when it flows out of the heat exchange module.

[0014] Optionally, the inspection and control module further includes:

[0015] An infrared thermal radiation monitoring module is provided on a side of the crack simulation module away from the heating module, and a detection end of the infrared thermal radiation monitoring module is provided toward the crack simulation module for monitoring the surface temperature of the crack simulation module.

[0016] Optionally, the vertical plate in the crack simulation module, which is arranged close to the infrared thermal radiation monitoring module, is made of a transparent resin material with a thermal conductivity of 5 W / (m·K) or more.

[0017] Optionally, the inspection and control module further includes:

[0018] A control module is connected to the heating module, the first temperature monitoring module, the second temperature monitoring module and the infrared thermal radiation monitoring module respectively.

[0019] Optionally, the hydrothermal self-driven cycle experimental device further includes:

[0020] a delivery module, the delivery module being in communication with the heat exchange module and being used to deliver a heat absorbing medium to the heat exchange module;

[0021] Wherein, the control module is also connected to the conveying module.

[0022] Another aspect of the present application provides a hydrothermal self-driven cycle experimental method, which is applied to any of the hydrothermal self-driven cycle experimental devices described above, comprising:

[0023] Based on different fracture curves, fracture apertures, and fluid circulation paths, multiple sets of hydrothermal self-driven cycle experiments were carried out;

[0024] The heat exchange efficiency of multiple groups of hydrothermal self-driven cycle experiments was compared, and the parameter combination corresponding to the extreme value of heat exchange efficiency under different combinations of fracture curves, fracture apertures, and fluid circulation paths was determined as the target parameter combination.

[0025] Obtaining surface morphological characteristic information of the fracture simulation module corresponding to the target parameter combination, and calculating the fracture equivalent roughness used to characterize the roughness of the fracture surface;

[0026] Obtain the fluid circulation driving pressure corresponding to the actual heating power of the underground heat source, and combine it with the equivalent roughness of the fracture to calculate the actual fracture aperture required to achieve self-driven circulation of the fluid driven by the underground heat source in the fracture;

[0027] The actual heat exchange efficiency is calculated based on the actual crack opening and the equivalent crack roughness.

[0028] Optionally, the crack equivalent roughness complies with the formula:

[0029] ;

[0030] Where, is the crack equivalent roughness, is the number of sampling points on the fracture surface, is the height of each sampling point on the crack surface, is the average height of the sampling points on the crack surface.

[0031] Optionally, the actual crack opening complies with the formula:

[0032] ;

[0033] Where, is the fluid circulation driving pressure corresponding to the actual heating power of the underground heat source, is the density of the liquid phase fluid, is the density of the vapor phase fluid, is the acceleration due to gravity, is the vertical height of the crack, is the crack equivalent roughness, is the actual crack opening.

[0034] Optionally, the actual heat exchange efficiency complies with the formula:

[0035] ;

[0036] Where, is the actual heat exchange efficiency, is the Nusselt number, is the thermal conductivity of the heat absorbing medium, is the crack equivalent roughness, is the actual crack opening.

[0037] By means of the above technical solution, this application has at least the following beneficial effects:

[0038] The hydrothermal self-driven circulation experimental device and experimental method provided in this application are made according to the fracture curve by setting the first vertical plate and the second vertical plate of the fracture simulation module. The surface shape matches the fracture curve and the spacing distance is adjustable. It can simulate the real underground fracture with high fissure fissure realism. It can not only restore the fracture roughness characteristics through the irregular shape of the surface, but also change the fracture opening by adjusting the plate spacing, thereby effectively meeting the research needs of the self-driven circulation heat exchange mechanism of fluid under different fracture characteristics. In addition, by setting the spacing distance between the heating module and the heat exchange module to be adjustable, the circulation process of the fluid in the fracture under different paths can be simulated, so that the experimental device can more comprehensively cover the complex scenes of actual underground hydrothermal circulation, and provide key technical support for researchers to deeply explore the influence of the fluid circulation path on the hydrothermal self-driven circulation mechanism, which greatly improves the simulation accuracy and research value of the experimental results for the real geothermal system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic structural diagram of a hydrothermal self-driven cycle experimental device according to an optional embodiment of the present application;

[0040] Figure 2 This is a schematic structural diagram of a crack simulation module according to an optional embodiment of the present application;

[0041] Figure 3 This is a flow chart of a hydrothermal self-driven cycle experimental method according to an optional embodiment of the present application.

[0042] The reference numerals indicate:

[0043] 1. Crack simulation module; 11. First vertical plate; 12. Second vertical plate; 2. Heat exchange module; 3. Heating module; 4. Inspection and control module; 41. First temperature monitoring module; 42. Second temperature monitoring module; 43. Infrared thermal radiation monitoring module; 44. Control module; 5. Transport module. DETAILED DESCRIPTION

[0044] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or module referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0046] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two modules. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0047] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0048] See also Figure 1 and Figure 2As shown, according to an embodiment of the present application, a hydrothermal self-driven circulation experimental device is provided, including a fracture simulation module 1, a heat exchange module 2, a heating module 3 and a detection and control module 4; the fracture simulation module 1 has a flat fracture structure, including a first vertical plate 11 and a second vertical plate 12 arranged opposite to each other, and the spacing distance between the first vertical plate 11 and the second vertical plate 12 is adjustable. The first vertical plate 11 and the second vertical plate 12 are both made according to the fracture curve, and the surface shapes facing each other are consistent with the fracture curve; the heat exchange module 2 is arranged at the lateral end of the fracture simulation module 1, and a heat absorption medium flowing in a vertical direction is arranged in the heat exchange module 2, and the heat absorption medium is used to exchange heat with the fluid in the flat fracture; the heating module 3 is arranged at the bottom of one side of the fracture simulation module 1, and the spacing distance between the heating module 3 and the heat exchange module 2 is adjustable. The heating module 3 is used to simulate an underground heat source to heat the fluid in the flat fracture; the detection and control module 4 is used to determine the heat exchange efficiency of the heat exchange module 2.

[0049] In this embodiment, by setting the first vertical plate 11 and the second vertical plate 12 of the fracture simulation module 1 to be made according to the fracture curve, the surface shape is consistent with the fracture curve, and the spacing is adjustable, which can highly realistically simulate the real underground fracture. Not only can the fracture roughness characteristics be restored by the irregular shape of the surface, but the fracture opening can also be changed by adjusting the plate spacing, thereby effectively meeting the research needs of the self-driven circulation heat exchange mechanism of the fluid under different fracture characteristics. In addition, by setting the spacing between the heating module 3 and the heat exchange module 2 to be adjustable, the circulation process of the fluid in the fracture under different paths can be simulated, so that the experimental device can more comprehensively cover the complex scenes of actual underground hydrothermal circulation, providing key technical support for researchers to deeply explore the influence of the fluid circulation path on the hydrothermal self-driven circulation mechanism, and greatly improving the simulation accuracy and research value of the experimental results for the real geothermal system.

[0050] Among them, the fracture simulation module 1 is a flat fracture structure composed of a first vertical plate 11 and a second vertical plate 12 arranged relatively to each other, which is used to simulate the real fracture environment underground. In actual application scenarios, the first vertical plate 11 and the second vertical plate 12 are both made according to a pre-set fracture curve, and the surface shapes of the two facing each other are consistent with the fracture curve, which can simulate the uneven roughness characteristics of the underground fracture surface, and provide a reliable experimental basis for researchers to explore the flow and heat transfer laws of fluids under different fracture roughness conditions. At the same time, during the experimental preparation and parameter adjustment process, the spacing between the first vertical plate 11 and the second vertical plate 12 can be flexibly adjusted. By changing the spacing between the plates, fracture conditions with different openings can be simulated to meet the needs of studying fluid dynamics and heat transfer characteristics under a variety of fracture opening conditions.

[0051] Specifically, in terms of manufacturing process, the fracture simulation module 1 can be prepared using 3D printing technology. First, based on the pre-set fracture curve, the high thermal conductivity resin material is processed into a first vertical plate 11 and a second vertical plate 12 with a specific shape and size using 3D printing equipment. The selection of high thermal conductivity resin material helps to more realistically simulate the thermal conductivity characteristics of the underground fracture wall and reduce experimental errors caused by differences in material thermal properties. Subsequently, the corresponding matching first vertical plate 11 and second vertical plate 12 are assembled and combined, and organic silicone is used to seal the gaps around to ensure that the fracture simulation module 1 has good sealing properties and prevent leakage of experimental fluids, ultimately forming a complete flat-plate fracture structure, providing a stable and reliable fracture simulation environment for the hydrothermal self-driven cycle experiment. It should be noted that during the production process of the fracture simulation module 1, the spacing distance between the first vertical plate 11 and the second vertical plate 12 can be adjusted by controlling the amount of organic silicone in the assembly link. Specifically, when assembling the corresponding first vertical plate 11 and the second vertical plate 12, the coating thickness and filling amount of the organic silicone are pre-set according to the target crack opening. The organic silicone not only plays a role in sealing and leak prevention, but the thickness of the colloid after solidification also determines the distance between the two plates: increasing the amount of organic silicone applied will increase the distance between the two plates after the colloid solidifies, thereby simulating a large crack opening condition; conversely, reducing the amount of organic silicone, the colloid becomes thinner after solidification, and the distance between the two plates decreases accordingly, which can simulate a small crack opening environment. By precisely controlling the filling amount of organic silicone, the sealing of the crack simulation module 1 can be guaranteed, and the crack opening can be flexibly adjusted, providing a convenient and reliable adjustment method for exploring the self-driven circulation heat exchange mechanism of fluid under different crack characteristic conditions.

[0052] The fracture simulation module 1 is equipped with a heat exchange module 2 at its lateral end. Heat exchange module 2 can be a heat exchanger, and a heat-absorbing medium is located within the module, flowing vertically. In practical applications, the heat-absorbing medium primarily exchanges heat with the fluid within the fractures of the flat plate. When the underground heat source simulation device (i.e., heating module 3) heats the fluid within the fractures, the heated fluid flows through the fractures and comes into contact with the heat-absorbing medium within heat exchange module 2, achieving heat transfer.

[0053] Specifically, in this embodiment, the heat exchange module 2 is made of a metal pipe with good thermal conductivity, and the heat-absorbing medium inside the metal pipe is in indirect contact with the fluid in the crack to exchange heat. In actual application scenarios, the lateral ends of the crack simulation module 1 can be bonded to the outer wall of the metal pipe by organic silicone, and the fluid in the crack flows in the space outside the metal pipe, while the heat-absorbing medium flows inside the metal pipe. When the high-temperature crack fluid flows through the outer wall of the pipe, the heat will be conducted through the pipe wall to the heat-absorbing medium in the pipe. For example, a copper pipe can be used as the heat exchange module 2, which has a high thermal conductivity and can transfer heat quickly. At the same time, spiral protrusions or grooves are processed on the outer wall of the heat exchange module 2 to further increase the heat exchange area and enhance the heat transfer effect.

[0054] A heating module 3 is installed at the bottom of one side of the fracture simulation module 1. This module simulates an underground heat source and heats the fluid within the flat plate fracture. The adjustable distance between the heating module 3 and the heat exchange module 2 allows simulation of the fluid circulation process within the fracture along different paths, enabling the experimental device to more comprehensively cover the complex scenarios of actual underground hydrothermal circulation.

[0055] Specifically, the hydrothermal self-driven cycle within the flat plate fractures relies primarily on the density difference between the vapor and liquid phases generated by thermosiphoning as the driving force. The specific cycle process is as follows: When heating module 3 simulates an underground heat source to heat the fluid within the flat plate fractures, the liquid portion of the fluid vaporizes under the influence of thermosiphoning, forming a vapor-liquid mixture. Due to the presence of the vapor phase, the density of this mixture is significantly lower than that of the surrounding, unvaporized liquid. According to the principle of buoyancy, the lower-density vapor-liquid mixture generates an upward buoyancy force, causing it to flow upward. As the vapor-liquid mixture rises, it flows toward the side of heat exchange module 2. Once it reaches heat exchange module 2, the vapor-liquid mixture flows downward along heat exchange module 2. During this process, the vapor-liquid mixture exchanges heat with the heat-absorbing medium within heat exchange module 2. Because the temperature of the vapor-liquid mixture is higher than that of the heat-absorbing medium within heat exchange module 2, heat is spontaneously transferred from the high-temperature vapor-liquid mixture to the low-temperature heat-absorbing medium. After exchanging heat with the liquid within heat exchange module 2, the vapor portion of the vapor-liquid mixture gradually condenses into liquid, decreasing its temperature and increasing its density. Afterwards, this part of the fluid continues to flow and returns to the heating module 3. Under the continuous heating action of the heating module 3, the liquid in the fluid is partially vaporized again, the density becomes smaller again, and then it flows upward again. This cycle repeats itself, forming a stable self-driven flow cycle in the flat plate crack. In this process, by adjusting the spacing between the heating module 3 and the heat exchange module 2, the flow path of the fluid in the flat plate crack can be changed. The so-called different flow paths essentially refer to changes in the size of the fluid circulation flow loop. When the spacing between the heating module 3 and the heat exchange module 2 is increased, the fluid needs to flow through a longer crack channel to complete a cycle, which increases the length of the flow loop, increases the contact area of ​​the fluid with the crack wall during the flow process, and prolongs the contact time, thereby causing more complex changes in friction resistance, which in turn causes changes in the pressure gradient of the fluid. At the same time, the fluid exchanges heat with the surrounding environment over a longer path, and the temperature distribution becomes more complex. On the contrary, if the spacing between the two is reduced, the fluid circulation flow loop will be shortened, and its cycle period will be shortened accordingly. The flow velocity and flow distribution of the fluid in the crack will change, and the number of heat exchanges with the crack wall and the heat exchange module 2 per unit time will increase, causing the temperature distribution and pressure changes experienced by the fluid to present characteristics that are completely different from those of the long path cycle. In this way, the experimental device can simulate the operating conditions of the fluid in the actual underground hydrothermal circulation at different scales and different complexity paths, providing researchers with rich and diverse experimental data for in-depth exploration of the hydrothermal self-driven circulation mechanism. It should be noted that the spacing between the heating module 3 and the heat exchange module 2 can be adjusted by fixing the heating module 3 at different positions. Specifically, a plurality of sets of preset positioning holes are provided at the bottom of one side of the crack simulation module 1, and each set of positioning holes is linearly distributed along the lateral direction of the crack simulation module 1.The bottom of the heating module 3 is equipped with matching positioning pins, which can be accurately inserted into different groups of positioning holes to achieve horizontal fixation.

[0056] Among them, in order to clarify the heat transfer efficiency during the hydrothermal self-driven cycle and the impact of different working conditions on the heat exchange effect, the hydrothermal self-driven cycle experimental device also includes a detection and control module 4, which is used to determine the heat exchange efficiency of the heat exchange module 2.

[0057] Specifically, in actual application scenarios, the inspection and control module 4 can collect and analyze the temperature changes and flow data of the fluid in the crack during the experiment, as well as the temperature, flow rate and other parameters of the heat-absorbing medium in the heat exchange module 2, and use thermodynamic calculation models and algorithms to determine the heat exchange efficiency of the heat exchange module 2.

[0058] Furthermore, in this embodiment, in addition to studying the effects of fracture aperture, fracture roughness, and the fluid circulation path within the fracture channel on the heat transfer efficiency and fluid dynamics of the hydrothermal self-driven cycle, the effects of the heat transfer medium's properties on the heat transfer rate, cycle stability, and overall thermal performance of the system can be studied by selecting heat-absorbing media with different physical and chemical properties (such as liquids or phase-change materials with varying thermal conductivity, specific heat capacity, and phase transition temperatures). Furthermore, by adjusting the temperature difference between the heat-absorbing medium and the fluid within the fracture channel, the effect of the temperature difference on the heat exchange driving force, convective heat transfer coefficient, and the system's thermal equilibrium state can be studied. This allows for a more comprehensive understanding of the hydrothermal self-driven cycle mechanism and provides a theoretical basis for practical applications such as geothermal resource development and underground heat exchange system optimization.

[0059] In some possible implementations disclosed in this application, see Figure 1 As shown, the detection and control module 4 includes a first temperature monitoring module 41 and a second temperature monitoring module 42; the first temperature monitoring module 41 is arranged at the inlet of the heat exchange module 2, and is used to monitor the temperature of the heat-absorbing medium when it flows into the heat exchange module 2; the second temperature monitoring module 42 is arranged at the outlet of the heat exchange module 2, and is used to monitor the temperature of the heat-absorbing medium when it flows out of the heat exchange module 2.

[0060] The first temperature monitoring module 41 and the second temperature monitoring module 42 may be temperature probes. By providing temperature probes at the inlet and outlet of the heat exchange module 2, the temperature of the heat-absorbing medium entering and exiting the heat exchange module 2 can be accurately measured, providing basic data for subsequent calculations of heat exchange efficiency.

[0061] Specifically, according to thermodynamic principles, heat exchange efficiency is calculated as the ratio of the heat absorbed by the heat-absorbing medium to the total heat provided. In the hydrothermal self-driven cycle experimental device of this embodiment, the total heat provided can be determined using relevant parameters of the heating module. Since the heating power of the heating module represents the amount of heat provided per unit time, the total heat provided by the heating module during that time period can be calculated by multiplying the power by the time, combined with the heating time. Regarding the heat absorbed by the heat-absorbing medium, the first temperature monitoring module 41 and the second temperature monitoring module 42 calculate the temperature difference between the inlet and outlet of the heat-absorbing medium. Combined with the mass and specific heat capacity of the heat-absorbing medium, the heat absorbed by the heat-absorbing medium can be calculated.

[0062] In some possible implementations disclosed in this application, see Figure 1 As shown, the inspection and control module 4 also includes an infrared thermal radiation monitoring module 43, which is arranged on the side of the crack simulation module 1 away from the heating module 3, and the detection end of the infrared thermal radiation monitoring module 43 is arranged toward the crack simulation module 1, for monitoring the surface temperature of the crack simulation module 1.

[0063] Among them, the infrared thermal radiation monitoring module 43 can be a thermal infrared imager, which can quickly obtain the surface temperature distribution of the crack simulation module 1 without directly contacting the surface through the principle of infrared thermal radiation.

[0064] Specifically, the detection end of the infrared thermal radiation monitoring module 43 is positioned toward the fracture simulation module 1, enabling real-time capture of the dynamic changes in the surface temperature of the fracture simulation module 1. During the hydrothermal self-driven cycle experiment, the surface temperature of the fracture simulation module 1 continuously changes with fluid circulation, heat exchange, and changes in experimental conditions. The infrared thermal radiation monitoring module 43 can present these changes in real-time as images or data, allowing researchers to intuitively and promptly observe temperature fluctuations and abnormal changes, facilitating in-depth analysis of heat transfer processes and fluid flow characteristics.

[0065] In some possible embodiments disclosed in the present application, the vertical plate disposed near the infrared thermal radiation monitoring module 43 in the crack simulation module 1 is made of a transparent resin material with a thermal conductivity of 5 W / (m·K) or more.

[0066] Among them, when the heating module 3 is set at the bottom of the first vertical plate 11 on the side away from the second vertical plate 12, the vertical plate set close to the infrared thermal radiation monitoring module 43 in the crack simulation module 1 is the second vertical plate 12; when the heating module 3 is set at the bottom of the second vertical plate 12 on the side away from the first vertical plate 11, the vertical plate set close to the infrared thermal radiation monitoring module 43 in the crack simulation module 1 is the first vertical plate 11.

[0067] Specifically, when the vertical plate near the infrared thermal radiation monitoring module 43 in the fracture simulation module 1 is made of a transparent resin material, researchers can directly observe the internal conditions of the fracture simulation module 1. For example, during the experiment, researchers can clearly see the flow state of the fluid in the fracture simulation module 1 through this transparent vertical plate, such as whether it is laminar or turbulent flow, and whether there are vortices. This provides researchers with a direct visual basis for in-depth understanding of the physical phenomena during the experiment and facilitates analysis and interpretation of experimental results.

[0068] Among them, when the vertical plate close to the infrared thermal radiation monitoring module 43 in the crack simulation module 1 is made of a transparent resin material with a thermal conductivity of 5W / (m·K) or above, the heat inside the crack simulation module 1 can be effectively transferred to the surface of the vertical plate, so that the infrared thermal radiation monitoring module 43 located on one side of the crack simulation module 1 can more accurately monitor the temperature of the vertical plate surface, and then invert the heat distribution and transfer inside the crack simulation module through the temperature data.

[0069] Specifically, in this embodiment, to ensure that the infrared thermal radiation monitoring module 43 can accurately capture the thermal radiation signals of the crack area, the thickness of the vertical plate near the infrared thermal radiation monitoring module 43 in the crack simulation module 1 is set to 5-10 mm. This thickness range effectively avoids the delay of heat conduction and the impact on monitoring sensitivity caused by excessively thick vertical plates, while also preventing the structural strength from being insufficient and deformation and damage from being caused during the simulation due to excessively thin plates. This balance is achieved between the accuracy of crack thermal radiation data collection and the reliability of module operation.

[0070] In some possible implementations disclosed in this application, see Figure 1 As shown, the detection and control module 4 further includes a control module 44 , which is connected to the heating module 3 , the first temperature monitoring module 41 , the second temperature monitoring module 42 and the infrared heat radiation monitoring module 43 respectively.

[0071] In this embodiment, the control module 44 can adjust the heating power or heating duration of the heating module 3 on the one hand; and can correlate and analyze the thermal radiation data with the temperature data on the other hand.

[0072] The control module 44 may be a computer.

[0073] Specifically, experiments under different working conditions have different requirements for temperature conditions. The control module 44 can flexibly adjust the working state of the heating module 3 according to the specific experimental settings, such as increasing the heating power so that the fluid in the crack meets the pressure required for the self-driven cycle. At the same time, the control module 44 correlates the thermal radiation data with the temperature data collected by the first temperature monitoring module 41 and the second temperature monitoring module 42, which can provide a deeper understanding of the heat transfer process inside and on the surface of the fracture simulation module 1. For example, by analyzing the distribution and changes of thermal radiation and combining it with temperature data, it is possible to infer the direction and speed of heat conduction inside the fracture simulation module 1 and whether there are local thermal anomalies.

[0074] In some possible implementations disclosed in this application, see Figure 1 As shown, the hydrothermal self-driven cycle experimental device also includes a conveying module 5, which is connected to the heat exchange module 2 and is used to convey the heat absorption medium to the heat exchange module 2; wherein, the control module 44 is also connected to the conveying module 5.

[0075] In this embodiment, the control module 44 can monitor the delivery of the heat absorbing medium to the heat exchange module 2 in real time, such as the flow information of the heat absorbing medium.

[0076] The delivery module 5 may be a syringe pump.

[0077] Specifically, in this embodiment, the control module 44 measures heat exchange efficiency through multi-source data acquisition and calculation. First, based on the operating parameters of the heating module 3, the control module 44 obtains its heating power and the heating duration set for the experiment, thereby calculating the total amount of heat provided by the heating module 3 during the experimental period. Secondly, to calculate the heat of the heat-absorbing medium, the control module 44 uses the first and second temperature monitoring modules 41, 42 to obtain the temperatures of the heat-absorbing medium as it flows into and out of the heat exchange module 2, respectively, and then calculates the temperature difference. Simultaneously, based on the delivery parameters of the delivery module 5, the control module 44 obtains the delivered volume of the heat-absorbing medium, calculates its mass based on the pre-set density of the heat-absorbing medium, and then calculates the actual amount of heat absorbed by the heat-absorbing medium based on the specific heat capacity of the heat-absorbing medium. Finally, the control module 44 substitutes these calculation results into thermodynamic equations to determine the heat exchange efficiency of the heat exchange module 2.

[0078] Furthermore, as a specific implementation of the above-mentioned hydrothermal self-driven cycle experimental device, the embodiment of the present application provides a hydrothermal self-driven cycle experimental method, see Figure 3 As shown, the method includes:

[0079] Step S101: Based on different fracture curves, fracture apertures, and fluid circulation paths, multiple groups of hydrothermal self-driven circulation experiments are carried out.

[0080] Here, by setting up multiple sets of experiments with different parameter combinations, we can fully understand the characteristics of the hydrothermal self-driven cycle under various conditions, and provide data support for the subsequent analysis of the relationship between heat exchange efficiency and these parameters.

[0081] Different fracture curves can be determined based on the ten standard roughness curves proposed by Barton. During experiments, researchers can directly select one or more of these ten standard roughness curves as the basis for the production of vertical plates in the fracture simulation module 1. Through processes such as 3D printing, high-thermal-conductivity resin materials are processed into first and second vertical plates 11 and 12 that match the surface morphology of the selected curves. This simulates the uneven surface characteristics of real underground fractures, thereby systematically studying the self-driven circulation and heat exchange mechanism of fluids within the fractures under different roughness conditions.

[0082] Among them, different crack openings can be pre-set based on rock mechanics theory, relevant engineering experience data or preliminary experimental results, with multiple representative values ​​(such as 0.1mm, 0.3mm, 0.5mm, etc.) to simulate actual underground crack conditions of different widths.

[0083] Among them, different fluid circulation paths can be a variety of flow trajectory schemes pre-planned in combination with geological structure feature analysis.

[0084] Specifically, each set of hydrothermal self-driven cycle experiments corresponds to a heat exchange efficiency. In actual application scenarios, the test data can be monitored in real time by the detection and control module 4 of the hydrothermal self-driven cycle experimental device. The first temperature monitoring module 41 and the second temperature monitoring module 42 respectively record the temperature of the heat-absorbing medium at the inlet and outlet of the heat exchange module 2. Combined with parameters such as the flow rate and specific heat capacity of the heat-absorbing medium, the heat exchange amount between the fluid and the heat-absorbing medium in the experiment is calculated according to thermodynamic formulas, thereby obtaining the heat exchange efficiency. It should be noted that after completing each set of experiments, researchers will record in detail the corresponding fracture curve type, fracture aperture value, fluid circulation path characteristics, and heat exchange efficiency data. These data will together constitute a large experimental data set, laying a solid foundation for the subsequent comparative analysis of the changing patterns of heat exchange efficiency under different parameter combinations. For example, through data visualization, the relationship between fracture curve morphology, fracture aperture size, fluid circulation path, and heat exchange efficiency can be presented as a three-dimensional scatter plot or contour map, intuitively showing the influence trend of each parameter on the heat exchange efficiency, providing strong support for determining the target parameter combination corresponding to the extreme value of heat exchange efficiency.

[0085] Step S102: comparing the heat exchange efficiencies of multiple groups of hydrothermal self-driven cycle experiments, and determining the parameter combination corresponding to the extreme value of the heat exchange efficiency under different combinations of fracture curves, fracture apertures, and fluid circulation paths as the target parameter combination.

[0086] Here, the heat exchange efficiencies of multiple groups of experiments in step S101 are compared to find the maximum value of the heat exchange efficiency under different parameter combinations. The corresponding combination of fracture curve, fracture aperture and fluid circulation path is the target parameter combination.

[0087] The target parameter combination is the one that achieves the optimal heat exchange effect for the hydrothermal self-driven cycle. Determining this target parameter combination provides a key reference for subsequent research and helps identify the direction for optimizing heat exchange efficiency.

[0088] Step S103: obtaining surface morphological characteristic information of the fracture simulation module 1 corresponding to the target parameter combination, and calculating the fracture equivalent roughness used to characterize the roughness of the fracture surface.

[0089] Here, by calculating the fracture equivalent roughness, the interaction between fluid and fracture surface can be analyzed and understood more accurately.

[0090] The surface morphological characteristic information of the crack simulation module 1 can be obtained through various measurement methods, such as laser scanning, electron microscopy, etc.

[0091] Specifically, the surface morphological characteristic information includes at least: the number of sampling points on the crack surface, the height of each sampling point on the crack surface, and the average height of the sampling points on the crack surface. Based on the above surface morphological characteristic information, the calculation formula for the crack equivalent roughness is generated:

[0092] ;

[0093] Where, is the crack equivalent roughness, is the number of sampling points on the fracture surface, is the height of each sampling point on the crack surface, is the average height of the sampling points on the crack surface.

[0094] Step S104: Obtain the fluid circulation driving pressure corresponding to the actual heating power of the underground heat source, and calculate the actual fracture aperture required for the underground heat source to drive the fluid to realize self-driven circulation in the fracture in combination with the fracture equivalent roughness.

[0095] Here, the actual fracture aperture is determined to determine whether the fluid can achieve stable self-driven circulation under the given conditions of underground heat source heating power and fracture surface roughness (characterized by fracture equivalent roughness).

[0096] The process for obtaining the fluid circulation driving pressure corresponding to the actual heating power of the underground heat source is as follows: First, based on the thermosiphon principle and basic fluid mechanics equations, a mathematical model is established to describe the thermosiphon fluid circulation process. Then, the known actual heating power of the underground heat source and other relevant parameters are substituted into the relationship, and the corresponding thermosiphon fluid circulation driving pressure is solved through mathematical calculation. For example, for a simple thermosiphon model, the driving pressure is proportional to the heating power and inversely proportional to the product of the fluid density and the acceleration of gravity, as well as the fracture height. The specific value of the driving pressure can be obtained through specific numerical calculations.

[0097] The matching formula for the fluid circulation driving pressure corresponding to the actual fracture aperture and the actual heating power of the underground heat source is:

[0098] ;

[0099] Where, is the fluid circulation driving pressure corresponding to the actual heating power of the underground heat source, is the density of the liquid phase fluid, is the density of the vapor phase fluid, is the acceleration due to gravity, is the vertical height of the crack, is the crack equivalent roughness, is the actual crack opening.

[0100] Step S105: Calculate the actual heat exchange efficiency based on the actual crack opening and the crack equivalent roughness.

[0101] Here, calculating the actual heat exchange efficiency can reflect the heat exchange performance of the hydrothermal self-driven circulation system under actual operating conditions, providing a more accurate basis for system optimization and improvement.

[0102] The actual crack opening can be obtained from step S104, and the crack equivalent roughness can be obtained from step S103.

[0103] The calculation formula for actual heat exchange efficiency is:

[0104] ;

[0105] Where, is the actual heat exchange efficiency, is the Nusselt number, is the thermal conductivity of the heat absorbing medium, is the crack equivalent roughness, is the actual crack opening.

[0106] By applying the technical solution of this embodiment, multiple groups of hydrothermal self-driven cycle experiments based on different fracture curves, fracture apertures, and fluid circulation paths were carried out, comprehensively considering the influence of various key factors on the hydrothermal self-driven cycle. Different fracture curves can simulate the diverse morphologies of real underground fractures, and changes in fracture aperture and fluid circulation paths can also reflect the complex working conditions in actual situations, making the experiment closer to the real underground hydrothermal circulation scene and more accurately exploring the mechanism of the effect of various factors on the circulation process. Comparing the heat exchange efficiency of multiple groups of experiments and finding the target parameter combination corresponding to the extreme value of heat exchange efficiency helps to clarify the specific parameter configuration for achieving the optimal heat exchange efficiency under different conditions, so that practical applications can adjust the system settings according to these parameters to improve heat exchange efficiency and thus improve energy utilization efficiency. The surface morphological feature information of the fracture simulation module 1 corresponding to the target parameter combination is obtained, and the fracture equivalent roughness is calculated to quantify the roughness characteristics of the fracture surface. This enables more accurate consideration of the influence of fracture roughness, an important factor, when studying the flow and heat exchange of fluids in fractures, providing basic data for establishing more accurate theoretical models and numerical simulations, and helping to deeply understand the movement laws of fluids in rough fractures. Obtaining the fluid circulation driving pressure corresponding to the actual heating power of the underground heat source and calculating the actual fracture aperture in combination with the equivalent fracture roughness, combining the experimental results with the actual operating conditions of the underground heat source, can more accurately assess the fracture aperture required to achieve fluid self-driven circulation under actual conditions. This provides a key reference for the design and optimization of fractures in geothermal engineering, helping to improve the feasibility and stability of geothermal systems. Calculating the actual heat exchange efficiency based on the actual fracture aperture and the equivalent fracture roughness allows the experimental results to better reflect the performance of actual geothermal systems, helping engineers and researchers to more accurately evaluate and compare the heat exchange effects of geothermal systems under different design schemes or operating conditions, providing strong support for further improvement and optimization of geothermal systems.

[0107] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0108] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. The above are merely preferred embodiments of the present application. It should be noted that those skilled in the art may make various improvements and variations without departing from the technical principles of the present application, and such improvements and variations shall also be considered within the scope of protection of the present application.

Claims

1. A hydrothermal self-driven cycle experimental device, characterized in that: include: A fracture simulation module having a flat fracture structure, comprising a first vertical plate and a second vertical plate arranged opposite each other, wherein the spacing between the first vertical plate and the second vertical plate is adjustable, and the first vertical plate and the second vertical plate are both manufactured according to the fracture curve, and the shapes of the surfaces facing each other are consistent with the fracture curve; a heat exchange module, the heat exchange module being arranged at a lateral end of the fracture simulation module, wherein a heat absorbing medium flowing in a vertical direction is arranged in the heat exchange module, and the heat absorbing medium is used to exchange heat with the fluid in the fracture of the plate; A heating module, the heating module is arranged at the bottom of one side of the fracture simulation module, the spacing between the heating module and the heat exchange module is adjustable, and the heating module is used to simulate an underground heat source to heat the fluid in the flat plate fracture; A detection and control module is used to determine the heat exchange efficiency of the heat exchange module.

2. The hydrothermal self-driven cycle experimental device according to claim 1, characterized in that: The inspection and control module includes: a first temperature monitoring module, which is disposed at the inlet of the heat exchange module and is used to monitor the temperature of the heat absorbing medium when it flows into the heat exchange module; The second temperature monitoring module is arranged at the outlet of the heat exchange module and is used to monitor the temperature of the heat absorbing medium when it flows out of the heat exchange module.

3. The hydrothermal self-driven cycle experimental device according to claim 2, characterized in that: The inspection module also includes: An infrared thermal radiation monitoring module is provided on a side of the crack simulation module away from the heating module, and a detection end of the infrared thermal radiation monitoring module is provided toward the crack simulation module for monitoring the surface temperature of the crack simulation module.

4. The hydrothermal self-driven cycle experimental device according to claim 3, characterized in that: The vertical plate arranged near the infrared thermal radiation monitoring module in the crack simulation module is made of a transparent resin material with a thermal conductivity of more than 5W / (m·K).

5. The hydrothermal self-driven cycle experimental device according to claim 3, characterized in that: The inspection module also includes: A control module is connected to the heating module, the first temperature monitoring module, the second temperature monitoring module and the infrared thermal radiation monitoring module respectively.

6. The hydrothermal self-driven cycle experimental device according to claim 5, characterized in that: Also includes: a delivery module, the delivery module being in communication with the heat exchange module and being used to deliver a heat absorbing medium to the heat exchange module; Wherein, the control module is also connected to the conveying module.

7. A hydrothermal self-driven cycle experimental method, characterized in that: The hydrothermal self-driven cycle experimental device according to any one of claims 1 to 6 comprises: Based on different fracture curves, fracture apertures, and fluid circulation paths, multiple sets of hydrothermal self-driven cycle experiments were carried out; The heat exchange efficiency of multiple groups of hydrothermal self-driven cycle experiments was compared, and the parameter combination corresponding to the extreme value of heat exchange efficiency under different combinations of fracture curves, fracture apertures, and fluid circulation paths was determined as the target parameter combination. Obtaining surface morphological characteristic information of the fracture simulation module corresponding to the target parameter combination, and calculating the fracture equivalent roughness used to characterize the roughness of the fracture surface; Obtain the fluid circulation driving pressure corresponding to the actual heating power of the underground heat source, and combine it with the equivalent roughness of the fracture to calculate the actual fracture aperture required to achieve self-driven circulation of the fluid driven by the underground heat source in the fracture; The actual heat exchange efficiency is calculated based on the actual crack opening and the equivalent crack roughness.

8. The hydrothermal self-driven cycle experimental method according to claim 7, characterized in that: The crack equivalent roughness conforms to the formula: ； Where, is the crack equivalent roughness, is the number of sampling points on the fracture surface, is the height of each sampling point on the crack surface, is the average height of the sampling points on the crack surface.

9. The hydrothermal self-driven cycle experimental method according to claim 7, characterized in that: The actual crack opening conforms to the formula: ； Where, is the fluid circulation driving pressure corresponding to the actual heating power of the underground heat source, is the density of the liquid phase fluid, is the density of the vapor phase fluid, is the acceleration due to gravity, is the vertical height of the crack, is the crack equivalent roughness, is the actual crack opening.

10. The hydrothermal self-driven cycle experimental method according to claim 7, characterized in that: The actual heat exchange efficiency complies with the formula: ； Where, is the actual heat exchange efficiency, is the Nusselt number, is the thermal conductivity of the heat absorbing medium, is the crack equivalent roughness, is the actual crack opening.

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