A nanofluid-enhanced urban geothermal mining system and method

Abstract

The present invention relates to a nanofluid-enhanced urban geothermal mining system and method, the system includes a heat extraction pipeline, a heat exchange component and a nanofluid regulating component; the nanofluid regulating component is connected to the heat extraction pipeline; the nanofluid regulating component includes a storage tank and a control unit, and a concentration detection sensor, a temperature sensor and a concentration regulating unit connected to the control unit, the storage tank is connected to the heat extraction pipeline, the concentration detection sensor is used to detect the concentration of the nanofluid in the storage tank, the temperature sensor is used to detect the temperature of the nanofluid, and the concentration regulating unit is used to adjust the concentration of the nanofluid in the storage tank. Compared with the prior art, the present invention adjusts the fluid concentration in the entire circulation pipeline in real time according to the appropriate heat transfer concentration of the hybrid nanofluid at each temperature, thereby effectively ensuring the heat exchange performance of the nanofluid, improving the heat exchange efficiency of the geothermal circulation system and other advantages.

Description

Technical Field

[0001] The present invention relates to the field of geothermal exploitation technology, and in particular to a nanofluid-enhanced urban geothermal exploitation system and method. Background Art

[0002] Geothermal energy, as a clean and renewable energy form, is gaining more and more attention around the world. It is abundant in reserves, continuously generated from the earth's interior, and is almost unaffected by weather and seasons during its development and utilization, making it of extremely high utilization value. However, in the process of developing and utilizing geothermal energy, the efficiency of the geothermal circulation system has become one of the key factors restricting its development.

[0003] Traditional geothermal circulation systems mostly use water as the circulation medium. After absorbing heat in the geothermal well, the water is extracted and releases heat into the system, and then circulated again into the injection well. However, the heat transfer efficiency of water is relatively low. In order to achieve the same heat transfer effect, a larger flow rate is often required, which not only increases the operating cost of the system, but also limits the development efficiency of geothermal energy. Therefore, how to improve the heat transfer efficiency of the geothermal circulation system has become an urgent problem to be solved in the field of geothermal energy development.

[0004] In recent years, the rapid development of nanotechnology has provided new ideas for the optimization of geothermal circulation systems. By suspending nanoscale particles in traditional fluids, nanofluids with higher heat transfer performance can be prepared. The addition of nanoparticles can significantly improve the thermal conductivity of the fluid and the stability of the mixture, thereby improving the heat exchange efficiency of the geothermal circulation system. In practical applications, the selection of parameters such as the type, particle size and concentration of nanoparticles has a crucial influence on the heat transfer performance of nanofluids. How to select the appropriate nanofluid formula to maximize its heat transfer efficiency has become a major challenge in the application of nanofluids.

[0005] In addition, the working environment of the geothermal circulation system is complex and changeable, and the heat transfer performance of nanofluids at different temperatures will also be different. Therefore, how to monitor and intelligently adjust the concentration of nanofluids in the circulation in real time to ensure that it always maintains the best heat transfer state is also a key issue that needs to be solved when nanofluids are used in geothermal circulation systems.

[0006] In view of this, the present technical invention proposes a nanofluid enhanced urban geothermal exploitation system and method that can improve the heat exchange efficiency of the geothermal circulation system and reduce energy loss. Summary of the invention

[0007] The purpose of the present invention is to provide a nanofluid-enhanced urban geothermal extraction system and method in order to overcome the defect of the above-mentioned prior art that the concentration fluctuation of the nanofluid causes the heat transfer efficiency to be unable to maintain the optimal heat exchange state.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] This solution provides a nanofluid-enhanced urban geothermal extraction system, including a heat extraction pipeline, a heat exchange component, and a nanofluid regulating component;

[0010] The nanofluid regulating component is connected to a heat collection pipeline, part of which is arranged under the soil for collecting geothermal heat; one side of the heat exchange component is connected to the heat collection pipeline, and the other side is connected to a load;

[0011] The nanofluid regulating component includes a storage tank and a control unit, and a concentration detection sensor, a temperature sensor and a concentration regulating unit connected to the control unit. The storage tank is connected to a heat extraction pipeline. The concentration detection sensor is used to detect the concentration of the nanofluid in the storage tank. The temperature sensor is used to detect the temperature of the nanofluid. The concentration regulating unit is used to regulate the concentration of the nanofluid in the storage tank.

[0012] Preferably, the concentration regulating unit comprises a nanoparticle storage element and a water reservoir respectively connected to the control unit, the nanoparticle storage element is connected to the storage tank via a nanoparticle delivery pipeline, and the water reservoir is connected to the storage tank via a water delivery pipeline.

[0013] Preferably, there are a plurality of concentration detection sensors, each of which is disposed on the bottom edge and the side wall of the inner side of the storage tank, and is used to detect the real-time concentration of the nanofluid in the storage tank.

[0014] Preferably, there are multiple temperature sensors, each of which is arranged at the bottom of the inner side of the storage tank and at the inlet and outlet of the heat extraction pipeline in the storage tank, and is used to detect problems with the nanofluid in the storage tank and the circulating temperature of the nanofluid.

[0015] Preferably, an ultrasonic vibrator is installed at the bottom of the storage tank for dispersing the nanoparticles.

[0016] Preferably, a circulation pump and a flow meter are provided on the heat collection pipeline to control the flow rate of the nanofluid in the heat collection pipeline.

[0017] Preferably, the heat exchange component adopts a heat pump unit, which includes an expansion valve, a condenser, a compressor and an evaporator connected end to end in sequence, the heat collection pipeline is connected to the evaporator to obtain geothermal energy collected by the heat collection pipeline, and the condenser is connected to the load.

[0018] The present invention also provides an operation method of a nanofluid-enhanced urban geothermal mining system, comprising the following steps:

[0019] According to the relationship curves between the concentration of various nanofluids and thermal conductivity under various temperature gradients, the size and type of hybrid nanoparticles are selected, and the concentration system of thermal conductive nanofluids under different temperature gradients is constructed;

[0020] The hybrid nanofluid is placed in a storage tank and circulated through a heat collection pipeline to collect geothermal heat using the hybrid nanofluid;

[0021] During the circulation of the hybrid nanofluid, the real-time temperature of the nanofluid in the storage tank is detected by a temperature sensor, and the theoretical thermal conductivity concentration of the nanofluid is determined according to the temperature and thermal conductivity curve corresponding to the nanofluid;

[0022] The real-time concentration of the nanofluid in the storage tank is detected by a concentration detection sensor, and the actual concentration of the nanofluid in the storage tank is adjusted to the theoretical heat conduction concentration by a concentration adjustment unit.

[0023] Preferably, obtaining the relationship curves between the concentration of various nanofluids and the thermal conductivity under various temperature gradients includes the following specific steps:

[0024] Select the size and type of nanoparticles to be hybridized, set different gradients of nanoparticle concentrations and configure hybrid nanofluids;

[0025] Placing hybrid nanofluids of various concentrations in a constant temperature water bath, and measuring the thermal conductivity of the hybrid nanofluid when the temperature of the hybrid nanofluid reaches the temperature of the constant temperature water bath;

[0026] According to the test conditions and measurement results, the relationship curves between the concentration of various nanofluids and the thermal conductivity under various temperature gradients were drawn.

[0027] Preferably, the preparation of the hybrid nanofluid comprises the following steps: mixing the nanoparticles and water according to a ratio and stirring, and then placing the stirred nanofluid into an ultrasonic device for ultrasonic dispersion to obtain a hybrid nanofluid of a preset concentration.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) In this scheme, the nanofluid flows through the heat extraction pipeline under the soil and obtains geothermal energy. It then flows through the heat exchange component and transfers the geothermal energy to the load. The cooled nanofluid then returns to the storage tank of the nanofluid regulating component. The concentration of the nanofluid is adjusted by the concentration regulating unit according to the temperature and concentration of the nanofluid in the storage tank to ensure that the thermal conductivity of the nanofluid in the heat extraction pipeline is high.

[0030] The temperature and concentration of the nanofluid in the heat collection pipeline are detected by means of a storage tank connected to the heat collection pipeline in cooperation with a nanofluid regulating component. The control unit adjusts the concentration of the nanofluid in the storage tank through a concentration regulating unit, thereby achieving real-time monitoring and regulation of the nanofluid circulation system in the heat collection pipeline. The fluid concentration in the entire circulation pipeline is adjusted in real time according to the appropriate heat transfer concentration of the hybrid nanofluid at each temperature, thereby effectively ensuring the heat exchange efficiency of the nanofluid.

[0031] (2) The present invention uses a new type of hybrid nanofluid as a heat transfer medium. A single type of nanofluid cannot have good thermal conductivity and rheological properties at the same time. Many practical applications require a trade-off between several properties of nanofluids. By mixing such nanoparticles, the resulting hybrid nanofluid exhibits excellent thermophysical and rheological properties. Hybrid nanofluid is a uniform mixture of two or more nanoparticles with new physical and chemical bonds. The main idea of ​​hybrid nanofluids is that due to synergistic effects, there are significant improvements in thermophysics, fluid mechanics and heat transfer performance compared to single nanofluids. By mixing appropriate nanoparticle combinations, the desired heat transfer effect can be obtained even at low particle concentrations. Compared with traditional heat transfer medium water, hybrid nanofluids have great advantages and can significantly improve heat exchange efficiency at a smaller mass fraction.

[0032] (3) This scheme presets the heat-conducting nanofluid concentration system under different temperature gradients in the control unit. Based on intelligent control and adaptive adjustment technology, it realizes real-time monitoring and adjustment of the nanofluid circulation system. The fluid concentration in the entire circulation pipeline is adjusted in real time according to the appropriate heat transfer concentration of the hybrid nanofluid at each temperature, thereby effectively ensuring the heat transfer efficiency of the nanofluid.

[0033] (4) This scheme not only explores the influence of nanoparticle characteristics and fluid characteristics on the heat transfer efficiency of nanofluid circulation, but also explores the laws of nanofluid stability under multiple cycles, thereby providing theoretical guidance from more angles for engineering applications and helping to optimize the design and operation strategies of geothermal extraction systems.

[0034] (5) This solution provides a new nanofluid-enhanced urban geothermal extraction system and method. The system only requires the addition of some devices to the previous heat exchange system. It is simple, safe, and easy to construct to achieve efficient geothermal extraction.

[0035] (6) This solution improves the heat exchange efficiency of the geothermal circulation system, which helps reduce energy loss and dependence on fossil fuels, and achieves the goals of energy conservation, emission reduction and cost reduction. At the same time, the multifunctional utilization of geothermal energy and the increase in energy supply also bring significant economic and environmental benefits to society. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the preparation method of the nanofluid of the present invention;

[0037] Figure 2 It is a schematic diagram of the nanofluid enhanced urban geothermal exploitation system of the present invention.

[0038] Figure numerals: 1. nanoparticles, 2. water, 3. stirring device, 4. ultrasonic device, 5. nanofluid, 6. nanoparticle storage element, 7. water reservoir, 8. nanoparticle delivery pipeline, 9. water delivery pipeline, 10. hybrid nanofluid, 11. concentration detection sensor, 12. circulation pump, 13 temperature sensor, 14. ultrasonic vibrator, 15. heat extraction pipeline, 16. soil, 17. heat pump unit, 18. expansion valve, 19. condenser, 20. compressor, 21. evaporator, 22. indoor air-conditioning system of building. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0042] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0043] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0044] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] Example 1

[0046] like Figure 2 As shown, this embodiment provides a nanofluid-enhanced urban geothermal production system, including a heat production pipeline, a heat exchange component and a nanofluid regulating component;

[0047] The nanofluid regulating component is connected to the heat collection pipeline, and part of the heat collection pipeline is set under the soil to collect geothermal heat; one side of the heat exchange component is connected to the heat collection pipeline, and the other side is connected to the load;

[0048] The nanofluid regulating component includes a storage tank and a control unit, as well as a concentration detection sensor, a temperature sensor and a concentration regulating unit connected to the control unit. The storage tank is connected to a heat extraction pipeline. The concentration detection sensor is used to detect the concentration of the nanofluid in the storage tank. The temperature sensor is used to detect the temperature of the nanofluid. The concentration regulating unit is used to regulate the concentration of the nanofluid in the storage tank.

[0049] Working principle: The nanofluid flows under the soil through the heat extraction pipeline and obtains geothermal heat, then flows through the heat exchange component, and transfers the obtained geothermal energy to the load through the heat exchange component. The cooled nanofluid then returns to the storage tank of the nanofluid regulating component. According to the temperature and concentration of the nanofluid in the storage tank, the control unit adjusts the concentration of the nanofluid through the concentration regulating unit to ensure that the thermal conductivity of the nanofluid in the heat extraction pipeline is high.

[0050] The temperature and concentration of the nanofluid in the heat collection pipeline are detected by means of a storage tank connected to the heat collection pipeline in cooperation with a nanofluid regulating component. The control unit adjusts the concentration of the nanofluid in the storage tank through a concentration regulating unit, thereby achieving real-time monitoring and regulation of the nanofluid circulation system in the heat collection pipeline. The fluid concentration in the entire circulation pipeline is adjusted in real time according to the appropriate heat transfer concentration of the hybrid nanofluid at each temperature, thereby effectively ensuring the heat exchange efficiency of the nanofluid.

[0051] In a preferred embodiment, the concentration adjustment unit includes a nanoparticle storage element 6 and a water reservoir 7 respectively connected to the control unit, wherein the nanoparticle storage element 6 is connected to the reservoir via a nanoparticle delivery pipeline 8, and the water reservoir 7 is connected to the reservoir via a water delivery pipeline 9. Nanoparticles are added to the reservoir via the nanoparticle storage element 6 to increase the concentration of the hybrid nanofluid 10, and water is added to the reservoir to reduce the concentration of the hybrid nanofluid 10. The adjustment structure is simple, convenient, accurate and reliable.

[0052] Furthermore, there are multiple concentration detection sensors 11, and each concentration detection sensor 11 is arranged on the bottom edge and the side wall inside the storage tank to detect the real-time concentration of the nanofluid in the storage tank.

[0053] Furthermore, there are multiple temperature sensors 13, each of which is arranged at the bottom of the inner side of the storage tank and at the inlet and outlet of the heat extraction pipeline in the storage tank, for detecting problems of the nanofluid in the storage tank and the circulating temperature of the nanofluid.

[0054] In an optional embodiment, an ultrasonic vibrator 14 is installed at the bottom of the storage tank for dispersing the nanoparticles. The ultrasonic vibrator 14 installed at the bottom of the storage tank can perform a quasi-stirring treatment on the nanoparticles and water added to the storage tank by the concentration adjustment unit, so that the concentration of the hybrid nanofluid 10 is uniform everywhere, thereby improving the detection accuracy of the concentration detection sensor 11.

[0055] Specifically, a circulation pump 12 and a flow meter are provided on the heat collection pipeline 15 to control the flow rate of the nanofluid in the heat collection pipeline 15 .

[0056] Among them, the heat exchange component adopts a heat pump unit 17, which includes an expansion valve 18, a condenser 19, a compressor 20 and an evaporator 21 connected end to end in sequence. The heat collection pipeline 15 is connected to the evaporator 21 for obtaining geothermal energy collected by the heat collection pipeline 15, and the condenser 19 is connected to the load.

[0057] This embodiment also provides an operation method based on the nanofluid enhanced urban geothermal exploitation system, comprising the following steps:

[0058] According to the relationship curves between the concentration of various nanofluids and thermal conductivity under various temperature gradients, the size and type of hybrid nanoparticles are selected, and the concentration system of thermal conductive nanofluids under different temperature gradients is constructed;

[0059] The hybrid nanofluid is placed in a storage tank and circulated through a heat collection pipeline to collect geothermal heat using the hybrid nanofluid;

[0060] During the circulation of the hybrid nanofluid, the real-time temperature of the nanofluid in the storage tank is detected by a temperature sensor, and the theoretical thermal conductivity concentration of the nanofluid is determined according to the temperature and thermal conductivity curve corresponding to the nanofluid;

[0061] The real-time concentration of the nanofluid in the storage tank is detected by a concentration detection sensor, and the actual concentration of the nanofluid in the storage tank is adjusted to the theoretical heat conduction concentration by a concentration adjustment unit.

[0062] like Figure 2 As shown, further, obtaining the relationship curves between the concentration of various nanofluids and the thermal conductivity under various temperature gradients includes the following specific steps:

[0063] Select the size and type of nanoparticles to be hybridized, set different gradients of nanoparticle concentrations and configure hybrid nanofluids;

[0064] Placing hybrid nanofluids of various concentrations in a constant temperature water bath, and measuring the thermal conductivity of the hybrid nanofluid when the temperature of the hybrid nanofluid reaches the temperature of the constant temperature water bath;

[0065] According to the test conditions and measurement results, the relationship curves between the concentration of various nanofluids and the thermal conductivity under various temperature gradients were drawn.

[0066] Furthermore, the preparation of the hybrid nanofluid includes the following steps: mixing the nanoparticles and water according to a ratio and stirring, and then placing the stirred nanofluid into an ultrasonic device for ultrasonic dispersion to obtain a hybrid nanofluid of a preset concentration.

[0067] In combination with the above preferred implementation, this embodiment provides a more specific implementation, including the following specific steps:

[0068] Step 1, select and determine the size of hybrid nanoparticles 1, the type of hybrid nanoparticles 1, and set different gradients of nanoparticle concentration to prepare hybrid nanofluids. First, the nanoparticles 1 and water 2 are stirred according to the ratio through a stirring device 3, and then placed in an ultrasonic device 4 for ultrasonic dispersion to prepare nanofluid 5. Each prepared nanofluid is placed in a constant temperature water bath in turn, and the thermal conductivity is measured when the temperature of the nanofluid reaches the water bath temperature, and the relationship curve between the concentration of various nanofluids and the thermal conductivity under each temperature gradient is drawn. According to the relationship curve, suitable nanoparticles and particle sizes are selected, and a suitable heat-conducting nanofluid concentration system under different temperature gradients is constructed.

[0069] Step 2: Construct a circulating heat transfer device based on the preferred hybrid nanofluid. Add a nanofluid storage tank to the circulation pipeline to add nanofluid to the pipeline in time and adjust its concentration. Set up a nanoparticle storage device and a water reservoir, connect them to the nanofluid storage tank through a nanoparticle delivery pipeline and a water delivery pipeline, and add nanoparticles and water therein in time. Set nanofluid concentration sensors at the bottom and around the nanofluid storage tank to detect the real-time concentration of the nanofluid in the storage tank. Place an ultrasonic vibrator at the bottom of the nanofluid storage tank to disperse the nanofluid. Place temperature sensors at the bottom of the nanofluid storage tank and at the inlet and outlet of the circulation pipeline to detect the temperature of the nanofluid in the storage tank and the circulation temperature. Place a circulation pump and a flowmeter on the circulation pipeline to control the circulation speed and detect the flow rate.

[0070] Step 3: prepare a suitable hybrid nanofluid in a nanofluid storage tank according to the preferred hybrid nanofluid ratio; set the circulation speed according to the ground source heat pump operation specification, so that the nanofluid begins to circulate in the circulation system;

[0071] The temperature of the nanofluid in the nanofluid storage tank is obtained according to the temperature sensor, and the appropriate nanofluid thermal conductivity concentration at each temperature is obtained according to the calibrated temperature-thermal conductivity curve;

[0072] When the concentration of the nanofluid in the storage tank is higher than the appropriate concentration, the water reservoir is controlled to add an appropriate amount of water to the storage tank until the appropriate concentration is reached, and the ultrasonic vibrator is turned on to vibrate;

[0073] When the nanofluid concentration in the storage tank is lower than the appropriate concentration, the nanoparticle storage device is controlled to add an appropriate amount of nanoparticles to the storage tank until the appropriate concentration is reached, and the ultrasonic vibrator is turned on for vibration.

[0074] Step 4: In the subsequent cycle, the temperature of the nanofluid in the storage tank is monitored in real time, and the concentration of the nanofluid is further adjusted according to step 3 to ensure that it maintains a high heat transfer performance, thereby efficiently extracting geothermal energy.

[0075] Step 5. In the cooling state, the compressor in the ground source heat pump unit works on the refrigerant to make it circulate from vapor to liquid. The heat carried by the indoor air circulation is absorbed into the refrigerant through the evaporation of the refrigerant in the refrigerant / air heat exchanger. While the refrigerant is circulating, the refrigerant is condensed in the refrigerant / water heat exchanger, and the heat carried by the refrigerant is absorbed by the water circulation, and finally transferred to the groundwater or soil by the water circulation. In the process of indoor heat being continuously transferred to the ground, the room is cooled through the refrigerant-air heat exchanger.

[0076] In the heating state, the compressor in the ground source heat pump unit works on the refrigerant and reverses the refrigerant flow direction through the four-way valve. The underground water circulation absorbs the heat in the groundwater or soil, and the heat in the water circulation is absorbed into the refrigerant through the evaporation of the refrigerant in the refrigerant / water heat exchanger. While the refrigerant is circulating, the refrigerant in the refrigerant / air heat exchanger condenses, and the air circulation absorbs the heat carried by the refrigerant. In the process of continuous transfer of underground heat to the room, heating is provided to the room in the form of forced convection, natural convection or radiation.

[0077] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A nanofluid-enhanced urban geothermal mining system, characterized in that: It includes heat collection pipelines, heat exchange components and nanofluid regulating components; The nanofluid regulating component is connected to a heat collection pipeline, part of which is arranged under the soil for collecting geothermal heat; one side of the heat exchange component is connected to the heat collection pipeline, and the other side is connected to a load; The nanofluid regulating component includes a storage tank and a control unit, and a concentration detection sensor, a temperature sensor and a concentration regulating unit connected to the control unit. The storage tank is connected to the heat extraction pipeline. The concentration detection sensor is used to detect the concentration of the nanofluid in the storage tank. The temperature sensor is used to detect the temperature of the nanofluid. The concentration regulating unit is used to regulate the concentration of the nanofluid in the storage tank. The operation method of the system comprises the following steps: According to the relationship curves between the concentration of various nanofluids and thermal conductivity under various temperature gradients, the size and type of hybrid nanoparticles are selected, and the concentration system of thermal conductive nanofluids under different temperature gradients is constructed; The hybrid nanofluid is placed in a storage tank and circulated through a heat collection pipeline to collect geothermal heat using the hybrid nanofluid; During the circulation of the hybrid nanofluid, the real-time temperature of the nanofluid in the storage tank is detected by a temperature sensor, and the theoretical thermal conductivity concentration of the nanofluid is determined according to the temperature and thermal conductivity curve corresponding to the nanofluid; The real-time concentration of the nanofluid in the storage tank is detected by a concentration detection sensor, and the actual concentration of the nanofluid in the storage tank is adjusted to the theoretical thermal conductivity concentration by a concentration adjustment unit; The acquisition of the relationship curves between the concentration of various nanofluids and the thermal conductivity under various temperature gradients includes the following specific steps: Select the size and type of nanoparticles to be hybridized, set different gradients of nanoparticle concentrations and configure hybrid nanofluids; Placing hybrid nanofluids of various concentrations in a constant temperature water bath, and measuring the thermal conductivity of the hybrid nanofluid when the temperature of the hybrid nanofluid reaches the temperature of the constant temperature water bath; According to the test conditions and measurement results, the relationship curves between the concentration of various nanofluids and thermal conductivity under various temperature gradients are drawn; The preparation of the hybrid nanofluid comprises the following steps: mixing the nanoparticles and water according to a ratio and stirring, and then placing the stirred nanofluid into an ultrasonic device for ultrasonic dispersion to obtain a hybrid nanofluid of a preset concentration; The hybrid nanofluid is a uniform mixture of two or more nanoparticles with new physical and chemical bonds. The desired heat transfer effect is obtained at a low particle concentration through the combination of nanoparticles.

2. The nanofluid-enhanced urban geothermal production system according to claim 1 is characterized in that: The concentration adjustment unit comprises a nanoparticle storage element (6) and a water reservoir (7) respectively connected to the control unit; the nanoparticle storage element (6) is connected to the reservoir via a nanoparticle delivery pipeline (8); and the water reservoir (7) is connected to the reservoir via a water delivery pipeline (9).

3. The nanofluid-enhanced urban geothermal mining system according to claim 1 is characterized in that: The number of the concentration detection sensors (11) is plural, and each concentration detection sensor (11) is arranged on the bottom edge and the side wall inside the storage tank, and is used to detect the real-time concentration of the nanofluid in the storage tank.

4. The nanofluid-enhanced urban geothermal production system according to claim 1 is characterized in that: The number of the temperature sensors (13) is plural, and each temperature sensor (13) is arranged at the bottom of the inner side of the storage tank and at the inlet and outlet of the heat collection pipeline in the storage tank, and is used to detect the problem of the nanofluid in the storage tank and the circulating temperature of the nanofluid.

5. The nanofluid-enhanced urban geothermal production system according to claim 1 is characterized in that: An ultrasonic vibrator (14) is installed at the bottom of the storage tank to disperse the nanoparticles.

6. The nanofluid-enhanced urban geothermal production system according to claim 1 is characterized in that: The heat collection pipeline (15) is provided with a circulation pump (12) and a flow meter for controlling the flow rate of the nanofluid in the heat collection pipeline (15).

7. The nanofluid-enhanced urban geothermal production system according to claim 1 is characterized in that: The heat exchange component adopts a heat pump unit (17), and the heat pump unit (17) comprises an expansion valve (18), a condenser (19), a compressor (20), and an evaporator (21) which are connected end to end in sequence; the heat collection pipeline (15) is connected to the evaporator (21) for obtaining geothermal energy collected by the heat collection pipeline (15); and the condenser (19) is connected to a load.

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