A nanofluid experimental device and method suitable for deep rock geothermal heat transfer

Abstract

The present invention discloses a nanofluid experimental device and method suitable for deep rock geothermal heat transfer. A heating module, an ultrasonic liquid storage tank and a peristaltic pump are connected through a circulation pipeline to form a closed circulation loop; a thermal imager, a first temperature detector and a flow meter are provided on the pipelines connected to the heating module; the heating module includes a granite pipe, a copper pipe and a second temperature detector for detecting the wall temperature of the granite pipe, the copper pipe is sleeved outside the granite pipe and fits with it, and the copper pipe is evenly wrapped with a heating wire; both ends of the copper pipe are connected to the circulation pipeline; the control system is electrically connected to the first temperature detector, the second temperature detector, the power supply system and the peristaltic pump. The present invention proposes to use the rock heat source as the heat source boundary, and to directly contact the circulating nanofluid with the rock heat source boundary to explore its heat exchange law, which can more realistically and objectively simulate the heat exchange situation after the nanofluid contacts the rock heat source in the deep geothermal well.

Description

Technical Field

[0001] The present invention relates to the field of geothermal energy mining and heat exchange technology, and in particular to a nanofluid experimental device and method suitable for deep rock geothermal heat transfer. Background Art

[0002] Geothermal energy, as a new clean energy source, has abundant reserves and great development prospects. The development and utilization of geothermal energy fundamentally involves extracting the thermal energy stored deep underground to the surface through heat exchange.

[0003] Research on geothermal heat transfer mainly focuses on the boundary of soil heat sources. The Chinese invention application with application number CN199610009001.3 discloses a low-temperature soil heat source centralized heating system. This invention mainly targets the development of shallow geothermal energy to achieve the recycling extraction and utilization of geothermal energy. However, the temperature of soil heat sources is generally low, and the energy can only be used for residential heating. However, the rich thermal energy stored deep underground is mainly concentrated in rocks. Using rock heat sources as heat transfer boundary conditions to explore the heat transfer change laws of rock and nanofluid contact is the key to efficiently and fully exploiting geothermal energy. However, in the existing technology, there is no corresponding heat transfer experimental device to explore the nanofluid change laws of rock heat sources. Summary of the Invention

[0004] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a nanofluid experimental device and method suitable for deep rock geothermal heat transfer.

[0005] The present invention provides a nanofluid experimental device suitable for deep rock geothermal heat transfer, comprising a heating module, an ultrasonic liquid storage tank, a peristaltic pump, and a control system. The heating module, ultrasonic liquid storage tank, and peristaltic pump are connected via a circulation pipeline to form a closed circulation loop. A thermal imager, a first temperature detector, and a flow meter are provided on the pipeline connected to the heating module. An ultrasonic vibrator is provided in the ultrasonic liquid storage tank.

[0006] The heating module includes a granite pipe, a copper pipe, and a second temperature detector for detecting the wall temperature of the granite pipe. The copper pipe is sleeved outside the granite pipe and fits closely therewith. The copper pipe is evenly wrapped with a heating wire, which is electrically connected to a power supply system and is used to heat the copper pipe. Both ends of the copper pipe are connected to the circulation pipeline.

[0007] The control system is electrically connected to the first temperature detector, the second temperature detector, the power supply system and the peristaltic pump. When the second temperature detector detects that the granite pipeline has reached a preset temperature, the control system controls the peristaltic pump to operate. When the first temperature detector detects that the nanofluid in the circulation pipeline has reached a preset temperature, the control system controls the power supply system to stop supplying power and the heating wire to stop heating.

[0008] Furthermore, both ends of the copper pipe are connected to the circulation pipeline through two connecting valves, and the two connecting valves are fixed to both ends of the copper pipe through clamps.

[0009] Furthermore, the clamp includes two connecting valves and a screw rod, and the two connecting valves are arranged at both ends of the copper pipe. One connecting valve is provided with a rotating hole, and the other connecting valve is provided with a threaded hole. The screw rod passes through the threaded hole and is rotatably arranged in the rotating hole. The screw rod rotates, driving the connecting valve with the threaded hole to approach or move away from the connecting valve with the rotating hole.

[0010] Furthermore, the clamper also includes a spring, which is sleeved on the screw rod, and its two ends are respectively against the two connecting valves.

[0011] Furthermore, a rubber ring is provided between the connecting valve and the copper pipe.

[0012] Furthermore, it also includes a heat dissipation module, the heat dissipation module includes a low-temperature constant temperature bath, an internal coil and an external tube, the internal coil is arranged in the low-temperature constant temperature bath, the external tube is arranged outside the low-temperature constant temperature bath, and a circulation pipeline is connected to the internal coil and the external tube through a three-way valve;

[0013] Furthermore, an ultrasonic vibrator is provided in each of the low-temperature constant temperature baths.

[0014] Furthermore, the heating wire is a nickel flat wire.

[0015] A nanofluid experimental method suitable for deep rock geothermal heat transfer uses the above-mentioned nanofluid experimental device suitable for deep rock geothermal heat transfer; the specific steps are as follows:

[0016] S1, adding fluid into the ultrasonic storage tank;

[0017] S2, the power supply system starts heating the heating wire. When the second temperature detector detects that the set temperature has been reached, the peristaltic pump is turned on to start the nanofluid to flow in the closed loop. The first temperature detector collects temperature data, the thermal imager is turned on to record the state of the nanofluid, and the flow meter records the flow change of the nanofluid.

[0018] S3, the first temperature detector detects that the temperature of the nanofluid reaches the set temperature required for the experiment, and controls the heating wire to stop heating;

[0019] The temperature data collected by the first temperature detector is plotted into a nanofluid heating curve, and then the nanofluid heating curve is subtracted from the deionized water heating curve to obtain a nanofluid heating temperature difference curve, and the nanofluid relative heating heat transfer efficiency is obtained.

[0020] Furthermore, the nanofluid is a nanofluid. By adjusting the physical parameters of the nanoparticles, adjusting the flow rate and flow rate mode, a convective heat transfer experiment is conducted on the nanofluid to explore the influence of the physical properties of the nanoparticles, the physical properties of the nanofluid, and the physical properties of granite on the heat transfer efficiency of the nanofluid, evaluate the heat transfer effect, optimize the nano parameters, and select the fluid formula; wherein, the flow rate mode includes a step-up flow mode, a constant flow mode, and a step-down flow mode.

[0021] The nanofluid circulation heat transfer experimental device proposed in the present invention is suitable for deep rock geothermal heat transfer. It proposes to use the rock heat source as the heat source boundary and directly contact the circulating nanofluid with the rock heat source boundary to explore its heat transfer law. It more realistically and objectively simulates the heat exchange situation after the nanofluid contacts the rock heat source in medium-deep geothermal wells, providing more realistic, intuitive and effective theoretical guidance for medium-deep geothermal circulation heat exchange systems, thereby providing theoretical guidance from more angles for engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of a nanofluid experimental device suitable for deep rock geothermal heat transfer according to the present invention;

[0023] Figure 2 It is a partial structural diagram of the connecting valve;

[0024] Figure 3 Configure a flow diagram for nanofluids;

[0025] Figure 4 A photo of a granite pipe.

[0026] 1. Heating module; 11. Granite pipe; 12. Copper pipe; 13. Heating wire; 14. Second temperature detector; 2. Heat dissipation module; 21. Low-temperature constant temperature bath; 22. Internal coil; 23. External tube; 3. Ultrasonic liquid storage tank; 4. Peristaltic pump; 5. Control system; 6. Thermal imager; 7. First temperature detector; 8. Flow meter; 9. Connecting valve; 10. Clamp; 101. Screw; 20. Rubber ring. DETAILED DESCRIPTION

[0027] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0028] like Figure 1As shown, a nanofluid experimental device suitable for deep rock geothermal heat transfer of the present invention includes a heating module 1, an ultrasonic liquid storage tank 3, a peristaltic pump 4 and a control system 5. The heating module 1, the ultrasonic liquid storage tank 3 and the peristaltic pump 4 are connected by a circulation pipeline to form a closed circulation loop; a thermal imager 6, a first temperature detector 7 and a flow meter 8 are provided on the pipeline connected to the heating module 1; an ultrasonic vibrator is provided in the ultrasonic liquid storage tank 3;

[0029] The heating module 1 includes a granite pipe 11 and a copper pipe 12. The copper pipe 12 is sleeved outside the granite pipe 11 and fits closely to the granite pipe 11. The copper pipe 12 is evenly wrapped with a heating wire 13. The heating wire 13 is electrically connected to the power supply system and is used to heat the copper pipe 12. Both ends of the copper pipe 12 are connected to the circulation pipeline.

[0030] The control system 5 is electrically connected to the first temperature detector 7 and the power supply system, so that when the first temperature detector 7 detects that the fluid in the circulation pipeline reaches a preset temperature, the control system 5 controls the power supply system to stop supplying power and the heating wire 13 stops heating.

[0031] The control system 5 is electrically connected to the first temperature detector 7, the second temperature detector 14, the power supply system and the peristaltic pump 4. When the second temperature detector 14 detects that the granite pipe 11 has reached a preset temperature, the control system 5 controls the peristaltic pump 4 to operate. When the first temperature detector 7 detects that the nanofluid in the circulation pipeline has reached a preset temperature, the control system 5 controls the power supply system to stop supplying power and the heating wire 13 to stop heating.

[0032] The nanofluid circulation heat transfer experimental device proposed in the present invention is suitable for deep rock geothermal heat transfer. It proposes to use the rock heat source as the heat source boundary and directly contact the circulating nanofluid with the rock heat source boundary to explore its heat transfer law. It more realistically and objectively simulates the heat exchange situation after the nanofluid contacts the rock heat source in medium-deep geothermal wells, providing more realistic, intuitive and effective theoretical guidance for medium-deep geothermal circulation heat exchange systems, thereby providing theoretical guidance from more angles for engineering applications.

[0033] There are many ways to connect the two ends of the copper pipe 12 to the circulation pipeline. In this embodiment, the two ends of the copper pipe 12 are connected through two connecting valves 9 (such as Figure 2As shown in FIG1 , the connecting valve 9 is connected to the circulation pipeline. One end of the connecting valve 9 cylinder is connected to the circulation pipeline, and the other end face is fixed to the copper pipe 12. The two connecting valves 9 are fixed to the two ends of the copper pipe 12 by a clamp 10. The clamp 10 may include a screw rod 101. The two connecting valves 9 are arranged at the two ends of the copper pipe 12. One connecting valve 9 is provided with a rotating hole, and the other connecting valve 9 is provided with a threaded hole. The screw rod 101 is rotatably arranged in the rotating hole through the threaded hole. The screw rod 101 rotates, driving the connecting valve 9 with the threaded hole to move closer to or away from the connecting valve 9 with the rotating hole. The clamp 10 may also include a spring 102. The spring 102 is sleeved on the screw rod, and its two ends are respectively against the two connecting valves 10. A rubber ring 20 is also provided between the connecting valve 9 and the copper pipe 12 to ensure its sealing.

[0034] The heat dissipation module 2 may include a low-temperature constant temperature bath 21, a built-in coil 22 and an external tube 23. The built-in coil 22 is arranged in the low-temperature constant temperature bath 21, and the external tube 23 is arranged outside the low-temperature constant temperature bath 21. The circulation pipeline is connected to the built-in coil 22 and the external tube 23 through a three-way valve; when the flow rate needs to be changed for the next experiment after the experiment is completed, it can help me quickly cool the fluid.

[0035] Each low-temperature constant-temperature bath 21 is equipped with an ultrasonic vibrator for dispersing the nanofluid. Before the circulation device begins to circulate, the ultrasonic liquid storage tank begins to enter the ultrasonic state, which keeps the nanofluid (nanofluid) stored in the ultrasonic liquid storage tank in a well-dispersed state in advance. The ultrasonic liquid storage tank also remains in operation while the circulation device is circulating.

[0036] There are many locations where the peristaltic pump 4 is set in the closed circulation loop. In one practicable manner, the ultrasonic liquid storage tank is connected to the output end of the peristaltic pump 4 and the input end of the heat dissipation module 2 .

[0037] In one practicable manner, the heating wire 13 can be a nickel flat wire, the copper pipe 12 has a diameter of 50 to 55 mm, a wall thickness of 1 to 2 mm, and a length of 150 to 200 mm, and the copper pipe 12 is evenly wound with the nickel flat wire, which is connected to the power supply system at both ends. Figure 4 The wall thickness of the pipe (as shown) is 25 to 30 mm, the inner diameter of the pipe is 50 to 55 mm, and the length is 150 to 200 mm. The granite is drilled using a core drill with a diameter of 50 to 55 mm. The granite pipe 11 needs to be fixed on the two connecting valves 9. The entire section of granite needs to withstand the axial force provided by the clamp 10. Therefore, the granite pipe wall needs to have a reserved thickness to provide sufficient strength for the granite pipeline. Secondly, after the nanofluid flows through the granite pipeline, in order to observe the seepage situation after the nanofluid contacts the rock, the granite pipeline needs to leave a seepage space.

[0038] The thermal imager 6 may be a CS-3 vanadium oxide detector.

[0039] The control system 5 may be composed of a data signal transmission card and a computer, and the temperature signal is converted by the data signal transmission card into an electrical signal and transmitted to the computer.

[0040] A nanofluid experimental method suitable for deep rock geothermal heat transfer uses the above-mentioned nanofluid experimental device suitable for deep rock geothermal heat transfer; the specific steps are as follows: S1, adding fluid to an ultrasonic liquid storage tank;

[0041] In step S2, the power supply system starts heating the heating wire 13. When the second temperature detector detects that the set temperature has been reached, the peristaltic pump 4 is turned on to start the nanofluid to flow in the closed loop. The first temperature detector 7 collects temperature data, the thermal imager 6 is turned on to record the state of the nanofluid, and the flow meter 8 records the flow change of the nanofluid.

[0042] S3, the first temperature detector 7 detects that the temperature of the nanofluid reaches the set temperature required for the experiment, and controls the heating wire 13 to stop heating.

[0043] The temperature data collected by the first temperature detector 7 is plotted as a nanofluid heating curve, and then the nanofluid heating curve is subtracted from the deionized water heating curve to obtain a nanofluid heating temperature difference curve, and the nanofluid relative heating heat transfer efficiency is obtained.

[0044] By adjusting the physical parameters of nanoparticles, adjusting the flow rate and flow rate pattern, convective heat transfer experiments were conducted on nanofluids to explore the effects of the physical properties of nanoparticles, nanofluids, and granite on the heat transfer efficiency of nanofluids. The heat transfer effect was evaluated, and the nano parameters and fluid formula were optimized. Among them, the flow rate patterns include step-up flow pattern, constant flow pattern, and step-down flow pattern.

[0045] The nanofluid circulation heat exchange experimental device provided by the present invention can be used to conduct nanofluid heat exchange experiments at the rock heat source boundary. The experimental steps are as follows:

[0046] Step 1: Prepare a rock pipe. In this example, the rock sample used is Luotian monzonite granite. A standard diameter drill bit is used to drill the granite sample and extract the drilled core.

[0047] Step 2: Prepare a heating section, place the prepared granite pipe 11 into the copper pipe 12, evenly wrap the nickel flat wire around the outside of the pipe, and connect the nickel flat wire to the power supply system;

[0048] Step 3: Connect the prepared heating section to the holder 10, align the two ends of the heating section pipeline with the interfaces of the connecting valve 9, and place a rubber ring 20 in the middle. Use the screw rod 101 of the holder 10 to control the holding distance between the two connecting valves 9, and tightly connect the connecting valve 9 to the heating pipeline;

[0049] Step 4, such as Figure 3 As shown in the figure, nanofluid was prepared. In this example, CuO nanoparticles with a particle size of 40 nm were used to prepare 1000 mL of nanofluid according to the ratio of nanoparticle concentration of 1% and SDBS concentration of 1%. The preparation process is shown in the attached figure. Figure 3 As shown, a SDBS deionized water solution is first prepared, and the SDBS deionized water solution is magnetically stirred. During the stirring process, a certain mass fraction of nanoparticles is slowly added to the SDBS deionized water solution. After the nanoparticles are evenly dispersed in the base liquid, the solution is subjected to physical oscillation and ultrasonic oscillation to finally prepare a nanoparticle fluid.

[0050] Step 5, adding nanofluid, adding the prepared nanofluid into the ultrasonic liquid storage tank, and putting the ultrasonic liquid storage tank into an operating state;

[0051] Step 6, controlling the power supply system through the control system 5 to start heating the nickel flat wire;

[0052] Step 7: When the second temperature detector detects that the temperature of the heating section reaches the set temperature, the peristaltic pump 4 is turned on to allow the nanofluid to start flowing in the circulation experimental device;

[0053] Step 8: Turn on the temperature acquisition system to start collecting temperature data, turn on the thermal imager 6 to record the state of the nanofluid in the pipeline, and turn on the flow meter 8 to record the flow change of the nanofluid in the circulation device;

[0054] Step 9: When the first temperature detector 7 detects that the temperature of the nanofluid reaches the set temperature required for the experiment, the power supply system is turned off to stop heating the nickel flat wire, and the ultrasonic liquid storage tank is closed at the same time.

[0055] Step 10: Unplug the pipeline at the output end of the ultrasonic liquid storage tank, and keep the pipeline at the input end connected. At this time, keep the peristaltic pump 4 open. Due to the change in air pressure, the nanofluid retained in the circulation device pipeline will eventually flow back to the ultrasonic liquid storage tank along the pipeline. After there is no nanofluid remaining in the circulation experimental device, turn off the peristaltic pump 4 and reconnect the pipeline at the output end of the ultrasonic liquid storage tank.

[0056] The main factors affecting the nanofluid circulation heat transfer experiment are:

[0057] (1) Physical properties of nanoparticles, including nanoparticle size, nanoparticle concentration, nanoparticle type, and dispersant concentration;

[0058] (2) Physical properties of the fluid, including fluid viscosity, flow velocity, flow state, nanofluid suspension stability, etc.;

[0059] (3) Physical properties of the heat source boundary, including the porosity, permeability, and wettability of the granite.

[0060] Therefore, the influence of the above factors is taken into consideration in the design of nanofluid circulation heat transfer experiments. By adjusting the physical parameters of nanoparticles, adjusting the flow rate and the selection of flow rate mode, etc., convective heat transfer experiments are carried out on nanofluids to explore the influence of the physical properties of nanoparticles, the physical properties of nanofluids and the physical properties of granite on the heat transfer efficiency of nanofluids. The heat transfer effect is evaluated and the nano parameters and fluid formula are optimized. Finally, a more realistic, intuitive and effective theoretical guidance is provided for the actual deep geothermal circulation heat exchange system.

[0061] The nanofluid circulation heat transfer experimental device proposed in this invention, which is suitable for deep rock geothermal heat transfer, is used to explore the influence of the characteristics of the nanofluid itself and the characteristics of the rock heat source boundary on the heat transfer efficiency of the nanofluid. The rationality and similarity of the actual site need to be considered during the experiment, otherwise the value and credibility of the experiment will be weakened.

[0062] The nanofluid circulation heat transfer experimental device proposed in this invention is suitable for deep rock geothermal heat transfer. It proposes to use the rock heat source as the heat source boundary and directly contact the circulating heat exchange medium with the rock heat source boundary to explore its heat transfer law, and proposes to use nanofluid as the heat exchange medium of the circulation heat exchange system to improve the heat exchange efficiency of the circulation heat exchange system, which can produce huge benefits after experiencing multiple cycles. This experimental device directly uses rock as the heat source to directly contact the heat exchange medium for heat exchange, which more realistically and objectively simulates the heat exchange situation after the heat exchange medium and rock heat source contact in the medium-deep geothermal well, and provides more realistic, intuitive and effective theoretical guidance for the actual application of nanofluids in the medium-deep geothermal circulation heat exchange system. This experimental device not only explores the influence of nanoparticle characteristics and fluid characteristics on the heat transfer efficiency of nanofluid circulation and mechanism, but also explores the influence of different heat source boundaries (in addition to the rock heat source proposed in this invention, it also includes water bath, soil heat source, cementing cement, etc.) on the heat transfer efficiency of nanofluid, thereby providing more theoretical guidance for engineering applications from more angles.

[0063] Any matters not mentioned above shall be subject to the existing technology.

[0064] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A nanofluid experimental device suitable for deep rock geothermal heat transfer, characterized by: The device comprises a heating module, an ultrasonic liquid storage tank, a peristaltic pump and a control system. The heating module, the ultrasonic liquid storage tank and the peristaltic pump are connected through a circulation pipeline to form a closed circulation loop. The pipeline connected to the heating module is provided with a thermal imager, a first temperature detector and a flow meter. The ultrasonic liquid storage tank is provided with an ultrasonic vibrator. The heating module includes a granite pipe, a copper pipe, and a second temperature detector for detecting the wall temperature of the granite pipe. The copper pipe is sleeved outside the granite pipe and fits closely therewith. The copper pipe is evenly wrapped with a heating wire, which is electrically connected to a power supply system and is used to heat the copper pipe. Both ends of the copper pipe are connected to the circulation pipeline. The control system is electrically connected to the first temperature detector, the second temperature detector, the power supply system and the peristaltic pump. When the second temperature detector detects that the granite pipeline has reached a preset temperature, the control system controls the peristaltic pump to operate. When the first temperature detector detects that the nanofluid in the circulation pipeline has reached a preset temperature, the control system controls the power supply system to stop supplying power and the heating wire to stop heating.

2. The nanofluid experimental device suitable for deep rock geothermal heat transfer according to claim 1, characterized in that: The two ends of the copper pipe are connected to the circulation pipeline through two connecting valves, and the two connecting valves are fixed to the two ends of the copper pipe through clamps.

3. The nanofluid experimental device suitable for deep rock geothermal heat transfer according to claim 2, characterized in that: The clamp includes a screw rod, and two connecting valves are arranged at both ends of the copper pipe. One connecting valve is provided with a rotating hole, and the other connecting valve is provided with a threaded hole. The screw rod passes through the threaded hole and is rotatably arranged in the rotating hole. The screw rod rotates, driving the connecting valve with the threaded hole to move closer to or away from the connecting valve with the rotating hole.

4. The nanofluid experimental device suitable for deep rock geothermal heat transfer according to claim 3, characterized in that: The clamper also includes a spring, which is sleeved on the screw rod, and two ends of the spring are respectively against the two connecting valves.

5. The nanofluid experimental device suitable for deep rock geothermal heat transfer according to claim 2, characterized in that: A rubber ring is also provided between the connecting valve and the copper pipe.

6. The nanofluid experimental device suitable for deep rock geothermal heat transfer according to claim 3, characterized in that: It also includes a heat dissipation module, which includes a low-temperature constant temperature tank and a built-in coil. The built-in coil is arranged in the low-temperature constant temperature tank and is connected to the circulation pipeline through a three-way valve.

7. The nanofluid experimental device suitable for deep rock geothermal heat transfer according to claim 6, characterized in that: Ultrasonic vibrators are provided in the low-temperature constant temperature baths.

8. The nanofluid experimental device suitable for deep rock geothermal heat transfer according to claim 2, characterized in that: The heating wire is a nickel flat wire.

9. A nanofluid experimental method suitable for deep rock geothermal heat transfer, characterized by: Using the nanofluid experimental device suitable for deep rock geothermal heat transfer according to any one of claims 1 to 8; the specific steps are as follows: S1, adding fluid into the ultrasonic storage tank; S2, the power supply system starts heating the heating wire. When the second temperature detector detects that the set temperature has been reached, the peristaltic pump is turned on to make the nanofluid start to flow in the closed loop; The first temperature detector collects temperature data, the thermal imager is turned on to record the state of the nanofluid, and the flow meter records the flow change of the nanofluid; S3, the first temperature detector detects that the temperature of the nanofluid reaches the set temperature required for the experiment, and controls the heating wire to stop heating; The temperature data collected by the first temperature detector is plotted into a nanofluid heating curve, and then the nanofluid heating curve is subtracted from the deionized water heating curve to obtain a nanofluid heating temperature difference curve, and the nanofluid relative heating heat transfer efficiency is obtained.

10. The nanofluid experimental method applicable to deep rock geothermal heat transfer according to claim 9, characterized in that: By adjusting the physical parameters of nanoparticles, adjusting the flow rate and flow rate pattern, convective heat transfer experiments were conducted on nanofluids to explore the effects of the physical properties of nanoparticles, nanofluids, and granite on the heat transfer efficiency of nanofluids. The heat transfer effect was evaluated, and the nano parameters and fluid formula were optimized. Among them, the flow rate patterns include step-up flow pattern, constant flow pattern, and step-down flow pattern.

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