A Medium-Deep Geothermal Well Heat Transfer Capacity Tester and Testing Method

Abstract

The present invention belongs to the technical field of geothermal testing, and relates to a heat exchange capacity tester and a testing method for medium-deep geothermal wells, including: a cooling tower, a medium-deep concentric tube heat exchange well, a system workstation, a valve box, a water pump, and a data collector. The cooling tower is connected to the medium-deep concentric tube heat exchange well through the valve box. The system workstation collects pipeline data through the data collector. The present invention can timely and accurately record temperature, flow rate, and pressure signal data, and transmit the collected data to the system workstation through a communication converter. The system workstation can, through calculation, truly simulate the heat exchange capacity of the medium-deep concentric tube heat exchange well in the heat absorption mode of the medium-deep concentric tube heat exchange system to the soil in winter, and can test the heat absorption amount of underground rock and soil.

Description

Technical Field

[0001] The present invention belongs to the technical field of geothermal testing, and relates to a heat exchange capacity tester and a testing method for medium-deep geothermal wells. Background Art

[0002] After the 1980s, with the popularization and application of ground source heat pump technology in some European and American regions and Asian countries, the in-situ testing technology for geothermal energy thermophysical properties came into being. Sweden, Germany, the United States, Canada, the United Kingdom, Switzerland, Turkey, Japan, South Korea and other countries have successively developed in-situ testing equipment for geothermal energy thermophysical properties, and many of these equipment have been widely promoted and applied. The research on in-situ testing equipment for geothermal energy physical properties in China started relatively late, but now it has also independently developed various forms of testing equipment, accumulating a large amount of data and rich practical experience. At present, the geothermal energy thermophysical testing equipment is mainly aimed at the thermophysical testing of shallow strata, while for the tester of the heat exchange capacity of medium-deep concentric tube geothermal wells, there is a lack both technically and in the market. Since the application of medium-deep geothermal energy is becoming more and more extensive at present, the corresponding testing technology and equipment are particularly important and needed.

[0003] Therefore, an accurate, stable, convenient and reliable testing method or testing instrument is needed to specifically study the heat exchange capacity of deep wells, so as to provide a true and reliable data basis for the later heating design of geothermal wells, and calculate and analyze the test data of experimental projects, and gradually improve the technical database for the sustainable development and application of medium-deep geothermal energy. Summary of the Invention

[0004] The technical solution adopted by the present invention to solve the technical problems is: a heat exchange capacity tester for medium-deep geothermal wells, comprising: a cooling tower, a medium-deep concentric tube heat exchange well, a system workstation, a valve box, a water pump, and a first data collector. The cooling tower is connected with a cooling tower outlet water pipeline and a cooling tower inlet water pipeline. The medium-deep concentric tube heat exchange well is divided into an inner well central tube and an inner well annular tube. The inner well annular tube annularly wraps the inner well central tube. The medium-deep concentric tube heat exchange well, the inner well central tube, and the inner well annular tube are coaxial. The inner well central tube and the inner well annular tube are connected at the bottom of the well. The wellhead of the inner well central tube is connected with a central tube water pipeline, and the wellhead of the inner well annular tube is connected with an annular tube water pipeline. The medium-deep concentric tube heat exchange well is used for heat energy exchange between the external geothermal energy and the internal water circuit of the well; the system workstation is a computer system for analyzing the data collected by the first data collector; the cooling tower can simulate the actual heating and heat supply operation conditions on the user side;

[0005] The cooling tower outlet pipe, cooling tower inlet pipe, central pipe water pipe, and ring pipe water pipe are all connected to the valve box. A water pump is connected in series on the cooling tower outlet pipe. The valve box is used to control the adjustment and change of the water flow channels between the cooling tower outlet pipe, cooling tower inlet pipe, central pipe water pipe, and ring pipe water pipe; the control valve box can control the water flow direction between each pipe and form different up and down and inlet and outlet water flow channels;

[0006] A first data collector is provided at the connection between the cooling tower water inlet pipe and the cooling tower. The first data collector includes a first electromagnetic flow sensor, a first temperature sensor, and a first pressure sensor. The first data collector is electrically connected to the system workstation through a communication converter.

[0007] Preferably, the valve box is provided with a first valve, a second valve, a third valve, a fourth valve, a fifth valve and a sixth valve. The cooling tower outlet pipe is connected in series with the first valve and the second valve in sequence and then connected to the annular water pipe. The cooling tower inlet pipe is connected in series with the fourth valve and the sixth valve in sequence and then connected to the central water pipe. The two ends of the third valve are respectively connected to the middle section of the series connection between the first valve and the second valve and the middle section of the series connection between the fourth valve and the sixth valve. The two ends of the fifth valve are respectively connected to the cooling tower inlet pipe and the annular water pipe. By opening and closing the valves, the connection and disconnection between different pipes can be achieved, and finally the purpose of controlling the water flow direction between the pipes and forming different up and down and inlet and outlet water flow paths is achieved.

[0008] More preferably, the first valve, the second valve, the third valve, the fourth valve, the fifth valve, and the sixth valve are electrically connected to the system workstation; each valve can be an electrically controlled valve, and the valve opening and closing can be remotely controlled through the system workstation to achieve remote adjustment of the test water flow direction and water flow path.

[0009] Preferably, the cooling tower water inlet pipe is connected to the tap water pipe, and a seventh valve is connected in series between the cooling tower water inlet pipe and the tap water pipe. The tap water channel is used for filling water when the test is performed for the first time and for subsequent water replenishment.

[0010] Preferably, the water pump is a variable frequency circulating water pump; the variable frequency circulating water pump can control the size of the water flow in the pipeline in real time.

[0011] Preferably, a connector is provided at the wellhead of the medium-deep concentric tube heat exchange well, the central tube in the well is connected to the central pipe water pipeline through the connector, and the annular tube in the well is connected to the annular pipe water pipeline through the connector. The connector makes testing and loading and unloading more convenient and quick.

[0012] Preferably, a second data collector is provided at the connection between the cooling tower outlet pipeline and the cooling tower, a third data collector is provided at the connection between the annular pipe in the well and the annular pipe water pipeline, and a fourth data collector is provided at the connection between the central pipe in the well and the central pipe water pipeline. The second data collector includes a second electromagnetic flow sensor, a second temperature sensor, and a second pressure sensor. The third data collector includes a third electromagnetic flow sensor, a third temperature sensor, and a third pressure sensor. The fourth data collector includes a fourth electromagnetic flow sensor, a fourth temperature sensor, and a fourth pressure sensor. The second data collector, the third data collector, and the fourth data collector are all electrically connected to the system workstation through a communication converter.

[0013] Preferably, a check valve is connected in series at the outlet of the water pump, and the check valve is used to prevent the water flow in the pipeline from flowing back.

[0014] The present invention also discloses a method for testing the heat exchange capacity of a medium-deep geothermal well. The testing method uses the above-mentioned medium-deep geothermal well heat exchange capacity tester, and the method is as follows:

[0015] The heat exchange capacity Q of the medium-deep geothermal well = ρ × V × C P ×ΔT

[0016] In the formula: Q—the heat exchange amount of the buried pipe, kW

[0017] ρ—the density of water, kg / m 3

[0018] V—the volume flow rate of water, m 3 / s

[0019] C P ——The specific heat at constant pressure of water, kJ / (kg×℃)

[0020] ΔT—the temperature difference between the inlet and outlet water temperatures of the test device, ℃.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The present invention is provided with data collectors at both the inlet and outlet pipelines of the cooling tower end and the inlet and outlet pipelines of the medium-deep concentric pipe heat exchange well, which can record the temperature, flow rate, and pressure signal data in a timely and accurate manner. The collected data is transmitted to the system workstation through a communication converter. The system workstation can calculate and truly simulate the heat exchange capacity of the medium-deep concentric pipe heat exchange well in the heat absorption mode of the medium-deep concentric pipe heat exchange system to the soil in winter, and can test the heat absorption amount of the underground rock and soil.

[0023] 2. The cooling tower of the present invention simulates the actual operation of the user side. During the test, only one medium-deep concentric tube heat exchange well needs to be drilled, and a well pipe of the medium-deep concentric tube heat exchange well is connected to form a closed loop, which can accurately calculate the heat exchange capacity of the geothermal well and provide timely and effective data guidance for the project function design.

[0024] 3. The connection method of the central pipe water pipeline and the annular pipe water pipeline of the present invention to the inner central pipe and the inner annular pipe of the medium-deep concentric tube geothermal well through the connector is a flexible connection, which can effectively realize the rapid connection and assembly of the pipeline.

[0025] 4. The present invention can realize a variety of test methods, including one in which the circulating water in the system enters the inner annular pipe of the medium-deep concentric tube geothermal well and discharges from the inner central pipe of the medium-deep concentric tube geothermal well into the cooling tower, and one in which the circulating water in the system enters the inner central pipe of the medium-deep concentric tube geothermal well and discharges from the inner annular pipe of the medium-deep concentric tube geothermal well into the cooling tower. Finally, the heat absorbed by the medium-deep concentric tube geothermal well from the soil and the rock and soil thermal conductivity coefficient in different water inlet directions are obtained through calculation.

[0026] 5. The on-site operation of the present invention is stable, the test accuracy is accurate, the whole test process runs automatically, the operation is convenient, and the performance is stable. It is also suitable for the long-term operation test research of medium-deep concentric tube geothermal wells. And it adopts a modular design, which can be quickly assembled and disassembled on-site. The module monomer is lightweight and small in volume, and can be flexibly transported by vehicle, which is very suitable for the test work on the construction site. Description of the Drawings

[0027] Figure 1 is a schematic diagram of a heat exchange capacity tester and test method for medium-deep geothermal wells;

[0028] Figure 2 is a schematic diagram of the test principle;

[0029] Figure 3 is a partial enlarged view of the geothermal well.

[0030] In the figure, 1 is a cooling tower; 2 is a medium-deep concentric tube heat exchange well; 3 is a system workstation; 4 is a valve box; 5 is a water pump; 6 is a first data collector; 7 is a cooling tower outlet water pipeline; 8 is a cooling tower inlet water pipeline; 9 is a central tube water pipeline; 10 is an annular tube water pipeline; 11 is a communication converter; 12 is a seventh valve; 13 is a connecting piece; 14 is a second data collector; 15 is a third data collector; 16 is a fourth data collector; 17 is a check valve; 201 is an in-well central tube; 202 is an in-well annular tube; 401 is a first valve; 402 is a second valve; 403 is a third valve; 404 is a fourth valve; 405 is a fifth valve; 406 is a sixth valve; 601 is a first electromagnetic flow sensor; 602 is a first temperature sensor; 603 is a first pressure sensor; 1401 is a second electromagnetic flow sensor; 1402 is a second temperature sensor; 1403 is a second pressure sensor; 1501 is a third electromagnetic flow sensor; 1502 is a third temperature sensor; 1503 is a third pressure sensor; 1601 is a fourth electromagnetic flow sensor; 1602 is a fourth temperature sensor; 1603 is a fourth pressure sensor. Detailed implementation manner

[0031] The following will clearly and completely describe the related technologies in the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] Reference Figures 1 to 3 , a medium-deep geothermal well heat exchange capacity tester, comprising: a cooling tower 1, a medium-deep concentric tube heat exchange well 2, a system workstation 3, a valve box 4, a water pump 5, and a first data collector 6. The cooling tower 1 is connected with a cooling tower outlet water pipeline 7 and a cooling tower inlet water pipeline 8. The medium-deep concentric tube heat exchange well 2 is divided into an in-well central tube 201 and an in-well annular tube 202. The in-well annular tube 202 annularly wraps the in-well central tube 201. The medium-deep concentric tube heat exchange well 2, the in-well central tube 201, and the in-well annular tube 202 are coaxial. The in-well central tube 201 and the in-well annular tube 202 are connected at the bottom of the well. The wellhead of the in-well central tube 201 is connected with a central tube water pipeline 9, and the wellhead of the in-well annular tube 202 is connected with an annular tube water pipeline 10. The medium-deep concentric tube heat exchange well 2 is used for heat energy exchange between the geothermal energy outside the well and the water path inside the well; the system workstation 3 is a computer system for analyzing the data collected by the first data collector 6; the cooling tower 1 can simulate the actual heating and heat supply operation conditions on the user side;

[0033] The cooling tower outlet water pipeline 7, the cooling tower inlet water pipeline 8, the central pipe water pipeline 9, and the annular pipe water pipeline 10 are all connected to the valve box 4. A water pump 5 is connected in series on the cooling tower outlet water pipeline 7. The valve box 4 is used to control the adjustment and change of the water flow channels between the cooling tower outlet water pipeline 7, the cooling tower inlet water pipeline 8, the central pipe water pipeline 9, and the annular pipe water pipeline 10; the control valve box 4 can control the water flow direction between each pipeline and form different up-and-down and inlet-outlet water flow paths;

[0034] A first data collector 6 is provided at the connection between the cooling tower inlet water pipeline 8 and the cooling tower 1. The first data collector 6 includes a first electromagnetic flow sensor 601, a first temperature sensor 602, and a first pressure sensor 603. The first data collector 6 is electrically connected to the system workstation 3 through a communication converter 11.

[0035] Furthermore, a first valve 401, a second valve 402, a third valve 403, a fourth valve 404, a fifth valve 405, and a sixth valve 406 are provided in the valve box 4. The cooling tower outlet water pipeline 7 is connected to the annular pipe water pipeline 10 in series after successively connecting the first valve 401 and the second valve 402. The cooling tower inlet water pipeline 8 is connected to the central pipe water pipeline 9 in series after successively connecting the fourth valve 404 and the sixth valve 406. Both ends of the third valve 403 are respectively connected to the series middle section between the first valve 401 and the second valve 402 and the series middle section between the fourth valve 404 and the sixth valve 406. Both ends of the fifth valve 405 are respectively connected to the cooling tower inlet water pipeline 8 and the annular pipe water pipeline 10; through the opening and closing allocation of each valve, the connection and disconnection between different pipelines can be realized, and finally the purpose of controlling the water flow direction between each pipeline and forming different up-and-down and inlet-outlet water flow paths can be achieved.

[0036] Even further, the first valve 401, the second valve 402, the third valve 403, the fourth valve 404, the fifth valve 405, and the sixth valve 406 are electrically connected to the system workstation 3; each valve can adopt an electric control valve, and the opening and closing on-off of the valve can be remotely controlled through the system workstation 3 to realize remote adjustment and test of the water flow direction and water flow path.

[0037] Furthermore, the cooling tower inlet water pipeline 8 is connected to the tap water pipeline, and a seventh valve 12 is connected in series between the cooling tower inlet water pipeline 8 and the tap water pipeline. The tap water channel is used for injecting water when testing for the first time and supplementing water volume subsequently.

[0038] Furthermore, the water pump 5 is a variable-frequency circulating water pump; the variable-frequency circulating water pump can control the size of the water flow in the pipeline in real time.

[0039] Furthermore, a connector 13 is provided at the wellhead of the medium-deep concentric tube heat exchange well 2. The central tube 201 in the well is connected to the central tube water pipeline 9 through the connector 13, and the annular tube 202 in the well is connected to the annular tube water pipeline 10 through the connector 13. The connector 13 makes the test loading and unloading more convenient and fast.

[0040] Furthermore, a second data collector 14 is provided at the connection between the cooling tower outlet water pipeline 7 and the cooling tower 1. A third data collector 15 is provided at the connection between the annular tube 202 in the well and the annular tube water pipeline 10. A fourth data collector 16 is provided at the connection between the central tube 201 in the well and the central tube water pipeline 9. The second data collector 14 includes a second electromagnetic flow sensor 1401, a second temperature sensor 1402, and a second pressure sensor 1403. The third data collector 15 includes a third electromagnetic flow sensor 1501, a third temperature sensor 1502, and a third pressure sensor 1503. The fourth data collector 16 includes a fourth electromagnetic flow sensor 1601, a fourth temperature sensor 1602, and a fourth pressure sensor 1603. The second data collector 14, the third data collector 15, and the fourth data collector 16 are all electrically connected to the system workstation 3 through a communication converter 11.

[0041] Furthermore, a check valve 17 is connected in series at the water outlet of the water pump 5. The check valve 17 is used to prevent the water flow in the pipeline from flowing back.

[0042] The present invention also discloses a method for testing the heat exchange capacity of a medium-deep geothermal well. The testing method uses the above-mentioned medium-deep geothermal well heat exchange capacity tester. The method is as follows:

[0043] The heat exchange capacity Q of the medium-deep geothermal well = ρ × V × C P × ΔT

[0044] In the formula: Q - the heat exchange amount of the buried pipe, kW

[0045] ρ - the density of water, kg / m 3

[0046] V - the volume flow rate of water, m 3 / s

[0047] C P —— the specific heat at constant pressure of water, kJ / (kg × °C)

[0048] ΔT - the temperature difference between the inlet and outlet water temperatures of the test device, °C.

[0049] Embodiment

[0050] The purpose of this embodiment is to provide a heat exchange capacity tester and a testing method for medium-deep geothermal wells. The tester can be vehicle-mounted and can accurately detect and test the heat exchange capacity of the medium-deep concentric tube geothermal well 2. In this embodiment, the tester adopts a modular design, which can be quickly assembled and disassembled on-site. The single module is light in weight and small in volume, and can be flexibly transported separately, which is very suitable for the testing work on the construction site.

[0051] The overall technical concept of this embodiment is:

[0052] A tester for the heat exchange capacity of a medium-deep concentric tube geothermal well, including a water connection pipe of a cooling tower 1 connected to a variable-frequency circulating water pump 5, and the variable-frequency circulating water pump 5 is connected to an annular pipe 202 in the well. A water connection pipe of the central pipe 201 in the well is connected to the cooling tower 1; control valves are arranged on each pipeline for switching; a check valve 17 is arranged on the pipeline to cut off the water flow in the control pipeline; a first data collector 6, a second data collector 14, a third data collector 15, and a fourth data collector 16 are arranged on the inlet and outlet water pipes of the cooling tower 1. Each collector is respectively provided with different electromagnetic flow sensors, temperature sensors, and pressure sensors. Each group of electromagnetic flow sensors, temperature sensors, and pressure sensors are electrically connected to the data collector; the data collector is electrically connected to a communication converter 11; the communication converter 11 is electrically connected to a system workstation 3; the system workstation 3 includes a data information collection unit and an information processing unit; the information collection unit is used for the data collector to collect the flow rate, temperature, and pressure information of the inlet and outlet water pipes, and provide this information to the information processing unit; the information processing unit is used for calculating the geotechnical thermal property parameters according to this information; the pipeline of the testing equipment for the heat exchange capacity of the medium-deep concentric tube geothermal well 2 is connected to the medium-deep concentric tube geothermal well 2 through a connector 13.

[0053] The specific technical content of this embodiment also includes:

[0054] To facilitate the real-time monitoring and control of the flow rate and temperature in the inlet pipeline and outlet pipeline of the cooling tower 1 to ensure the accuracy of the test results. The electromagnetic flow sensors and temperature sensors include electromagnetic flow sensors and temperature sensors arranged on the outlet water pipe and inlet water pipe of the cooling tower 1, electromagnetic flow sensors and temperature sensors arranged on the annular pipe 202 in the well of the medium-deep concentric tube geothermal well 2, and electromagnetic flow sensors and temperature sensors arranged on the central pipe 201 in the well of the medium-deep concentric tube geothermal well 2.

[0055] To ensure that the cooling tower 1 conveys water and drains water into the pipeline through the water pump 5 and conducts throttling control, a check valve 17 is arranged on the outlet water pipe of the variable-frequency circulating water pump 5. A variable-frequency circulating water pump 5 is arranged on the outlet water pipeline of the cooling tower 1.

[0056] To ensure that the pipeline of the test system is filled with a water medium, a tap water pipeline is connected to the central pipe water pipeline 9 of the medium-deep concentric tube geothermal well 2.

[0057] To ensure independent control of the water inflow of the external tap water pipeline, a seventh valve 12 is installed on the external tap water pipeline.

[0058] The communication converter 11 converts the input communication protocol of the lower computer (the data of the electromagnetic flow sensor, temperature sensor, and pressure sensor collected by the data collector) into a communication protocol that the system workstation 3 can accept.

[0059] This tester operates stably on-site, and the test accuracy meets the specification requirements. The entire test process runs automatically, with convenient operation and stable performance. It is also applicable to the long-term operation test research of the medium-deep concentric tube geothermal well 2.

[0060] This tester adopts a modular design and can be quickly assembled and disassembled on-site. The individual module is light in weight and small in volume, and can be transported flexibly by vehicle, which is very suitable for the test work on the construction site.

[0061] The working principle of this embodiment is as follows:

[0062] 1. Preparation work before testing:

[0063] Connect the pipeline of the test equipment for the heat exchange capacity of the medium-deep concentric tube geothermal well 2, that is, the cooling tower outlet pipeline 7, the cooling tower inlet pipeline 8, the central pipe water pipeline 9, and the annular pipe water pipeline 10 to the valve box 4. Open the seventh valve 12 and start the variable-frequency circulating water pump 5 to fill the well pipe of the medium-deep concentric tube geothermal well 2 and the pipeline of the test equipment for the heat exchange capacity of the medium-deep concentric tube geothermal well 2 with clear water. When the flow rate of the variable-frequency circulating water pump 5 is stable, it means that the water has filled the circulation pipeline, ensuring that the pipeline and the cooling tower 1 are unblocked, the instruments and meters are operating normally, start the equipment, and check the operation of each value test on the display screen of the upper system workstation 3.

[0064] 2. Testing work:

[0065] Perform initial settings on the system workstation 3. Then, the system workstation 3 automatically records the temperature and water pressure of the inlet and outlet pipes, the heating power, the circulating water flow rate, and the geothermal gradient, and calculates the rock and soil thermal conductivity and the heat exchange amount of the medium-deep concentric tube geothermal well 2, and then displays them on the display screen.

[0066] This embodiment tests and simulates the heat extraction situation of the medium-deep concentric tube geothermal well 2 from the surrounding soil and rock formations through the outer wall of the inner annular pipe 202 in the well and the bottom of the deep concentric tube geothermal well 2 under the winter heating condition. Start the variable-frequency circulating water pump 5 and start the cooling tower 1 (where the cooling tower 1 simulates the user end). The water temperature at the inlet and outlet of the cooling tower 1 and the water volume of the variable-frequency circulating water pump 5 can be controlled through the system workstation 3. There are two testing methods in this embodiment:

[0067] Testing method one:

[0068] The circulating water in the system enters the annular pipe 202 of the medium-deep concentric geothermal well 2, and is discharged from the central pipe 201 of the medium-deep concentric geothermal well 2 into the cooling tower 1. The first valve 401, the second valve 402, the fourth valve 404, and the sixth valve 406 in the valve box 4 are opened, and the third valve 403 and the fifth valve 405 are closed. The tap water enters the annular space of the annular pipe 202 in the well through the water pump 5, and after heat exchange, it is discharged through the central pipe 201 in the well into the cooling tower 1 for cooling. The heat exchange cycle is continuous. During the test, the flow rate is guaranteed to be 40m 3 / h fluctuates up and down, and no large flow changes can occur. The cycle is 72h, with an interval of 5min. The system workstation 3 records the water flow, inlet and outlet water temperature, and pipeline pressure of the four data collection points once, and finally calculates the heat absorbed from the soil by water through the medium-deep concentric pipe geothermal well 2 and the thermal conductivity of the rock and soil.

[0069] Test method 2:

[0070] The circulating water in the system enters the central pipe 201 of the medium-deep concentric geothermal well 2, and is discharged from the annular pipe 202 of the medium-deep concentric geothermal well 2 into the cooling tower 1. The first valve 401, the sixth valve 406, the fifth valve 405, and the third valve 403 in the valve box 4 are opened, and the second valve 402 and the fourth valve 404 are closed. The tap water enters the central pipe 201 of the medium-deep concentric geothermal well 2 through the water pump 5, and after heat exchange, it is discharged from the annular pipe 202 of the medium-deep concentric geothermal well 2 into the cooling tower 1 for cooling. The heat exchange is circulated continuously. During the test, the flow rate is ensured to be 40m 3 / h fluctuates up and down, and no large flow changes can occur. The cycle is 72h, with an interval of 5min. The system workstation 3 records the water flow, inlet and outlet water temperature, and pipeline pressure of the four data collection points once, and finally calculates the heat absorbed from the soil by water through the medium-deep concentric pipe geothermal well 2 and the thermal conductivity of the rock and soil.

[0071] The two test methods, due to the different directions of water inlet and outlet, result in different contact surfaces of the water inlet and outlet, and different heat conduction sequences, thus affecting the heat exchange of the water in the deep concentric tube well 202. In the first test method, the medium water enters from the annular tube 202 in the well. The low-temperature medium water in the annular tube 202 successively undergoes heat conduction heat exchange with the surrounding environment of the annular space (the annular casing and the surrounding soil and rock layers in contact with the annular casing at the bottom of the deep concentric tube well 202) and the soil and rock layers around the bottom of the deep concentric tube well 202, changing from low-temperature water to high-temperature water. The water is then discharged through the central tube 201 in the deep concentric tube geothermal well 2. During the discharge process, the medium water in the central tube 201 also undergoes heat exchange through the central tube wall and the water in the annular space. The medium water then enters the cooling tower 1. In the second test method, low-temperature medium water enters from the central tube 201 in the medium-deep concentric tube geothermal well 2, reaches the bottom of the medium-deep concentric tube well 202, and conducts heat conduction and heat exchange with the surrounding soil and rock formations, and then enters the annular tube 202 in the well, and then conducts heat conduction and heat exchange with the surrounding environment (the annular casing and the surrounding soil and rock formations in contact with the annular casing), changing from low-temperature water to high-temperature water, and then is discharged through the annular tube 202 in the well of the medium-deep concentric tube geothermal well 2. During the discharge process, the medium water in the annular tube 202 in the well will also undergo heat conduction and heat exchange through the water between the wall of the annular tube 202 and the central tube space, and then the medium water enters the cooling tower 1 again.

[0072] 3. Determination of the capacity (heat transfer capacity) of medium-deep concentric tube heat exchange wells and soil thermal properties:

[0073] Based on the test data recorded in the test, the capacity (heat transfer capacity) of the medium-deep concentric tube heat exchange well and the thermal conductivity of the rock and soil were calculated using the system workstation 3.

[0074] The capacity (heat exchange) of the deep concentric tube heat exchange well is Q = ρ × V × C P ×ΔT

[0075] Where: Q—heat exchange capacity of buried pipe, kW

[0076] ρ—density of water, kg / m 3

[0077] V—volume flow of water, m 3 / s

[0078] C P ——Specific heat of water at constant pressure, kJ / (kg×℃)

[0079] ΔT—the temperature difference between the inlet and outlet water of the test device, ℃.

[0080] In summary, the present invention provides a heat exchange capacity tester for medium and deep geothermal wells. By providing data collectors at both the inlet and outlet pipelines of the cooling tower and the inlet and outlet pipelines of the medium and deep concentric tube heat exchange wells, the temperature, flow rate, and pressure signal data can be recorded in a timely and accurate manner. The collected data is transmitted to the system workstation through a communication converter. The system workstation can calculate and truly simulate the heat exchange capacity of the medium and deep concentric tube heat exchange wells in the heat absorption mode of the medium and deep concentric tube heat exchange system to the soil in winter, and can measure the heat absorption of the underground rock and soil. Therefore, the present invention has a wide range of application prospects.

[0081] It should be emphasized that the above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A heat exchange capacity tester for medium-deep geothermal wells, characterized in that, Including: Cooling tower (1), medium-deep concentric tube heat exchange well (2), system workstation (3), valve box (4), water pump (5), first data collector (6). The cooling tower (1) is connected with a cooling tower outlet water pipe (7) and a cooling tower inlet water pipe (8). The medium-deep concentric tube heat exchange well (2) is divided into an inner well central tube (201) and an inner well annular tube (202). The inner well annular tube (202) annularly wraps the inner well central tube (201). The medium-deep concentric tube heat exchange well (2), the inner well central tube (201), and the inner well annular tube (202) are coaxial. The inner well central tube (201) and the inner well annular tube (202) are connected at the bottom of the well. The wellhead of the inner well central tube (201) is connected with a central tube water pipe (9). The wellhead of the inner well annular tube (202) is connected with an annular tube water pipe (10). The medium-deep concentric tube heat exchange well (2) is used for heat energy exchange between the geothermal energy outside the well and the water path inside the well. The cooling tower outlet water pipe (7), the cooling tower inlet water pipe (8), the central tube water pipe (9), and the annular tube water pipe (10) are all connected to the valve box (4). The water pump (5) is connected in series on the cooling tower outlet water pipe (7). The valve box (4) is used to control the adjustment and change of the water flow channels between the cooling tower outlet water pipe (7), the cooling tower inlet water pipe (8), the central tube water pipe (9), and the annular tube water pipe (10). At the connection between the cooling tower inlet water pipe (8) and the cooling tower (1), the first data collector (6) is provided. The first data collector (6) includes a first electromagnetic flow sensor (601), a first temperature sensor (602), and a first pressure sensor (603). The first data collector (6) is electrically connected to the system workstation (3) through a communication converter (11). The cooling tower inlet water pipe (8) is connected to the tap water pipe, and a seventh valve (12) is connected in series between the cooling tower inlet water pipe (8) and the tap water pipe. The water pump (5) is a variable frequency circulating water pump.

2. The heat exchange capacity tester for medium-deep geothermal wells according to claim 1, characterized in that The valve box (4) is provided with a first valve (401), a second valve (402), a third valve (403), a fourth valve (404), a fifth valve (405), and a sixth valve (406). The cooling tower outlet water pipe (7) is connected to the annular tube water pipe (10) after being connected in series with the first valve (401) and the second valve (402) in sequence. The cooling tower inlet water pipe (8) is connected to the central tube water pipe (9) after being connected in series with the fourth valve (404) and the sixth valve (406) in sequence. The two ends of the third valve (403) are respectively connected to the series middle section between the first valve (401) and the second valve (402) and the series middle section between the fourth valve (404) and the sixth valve (406). The two ends of the fifth valve (405) are respectively connected to the cooling tower inlet water pipe (8) and the annular tube water pipe (10).

3. The heat exchange capacity tester for medium-deep geothermal wells according to claim 2, wherein, The first valve (401), the second valve (402), the third valve (403), the fourth valve (404), the fifth valve (405), and the sixth valve (406) are electrically connected to the system workstation (3).

4. The heat exchange capacity tester for medium-deep geothermal wells according to claim 1, characterized in that, A connector (13) is provided at the wellhead of the medium-deep concentric tube heat exchange well (2). The central pipe (201) in the well is connected to the central pipe water pipeline (9) through the connector (13), and the annular pipe (202) in the well is connected to the annular pipe water pipeline (10) through the connector (13).

5. The heat exchange capacity tester for medium-deep geothermal wells according to claim 1, wherein A second data collector (14) is provided at the connection between the cooling tower outlet water pipeline (7) and the cooling tower (1). A third data collector (15) is provided at the connection between the annular pipe (202) in the well and the annular pipe water pipeline (10). A fourth data collector (16) is provided at the connection between the central pipe (201) in the well and the central pipe water pipeline (9). The second data collector (14) includes a second electromagnetic flow sensor (1401), a second temperature sensor (1402), and a second pressure sensor (1403). The third data collector (15) includes a third electromagnetic flow sensor (1501), a third temperature sensor (1502), and a third pressure sensor (1503). The fourth data collector (16) includes a fourth electromagnetic flow sensor (1601), a fourth temperature sensor (1602), and a fourth pressure sensor (1603). The second data collector (14), the third data collector (15), and the fourth data collector (16) are all electrically connected to the system workstation (3) through a communication converter (11).

6. The heat exchange capacity tester for medium-deep geothermal wells according to claim 1, characterized in that, A check valve (17) is connected in series at the water outlet of the water pump (5).

7. A method for testing the heat exchange capacity of a medium-deep geothermal well, characterized in that, The method uses the medium-deep geothermal well heat exchange capacity tester described in any one of claims 1 to 6. The method is as follows: The heat exchange capacity Q of a medium-deep geothermal well is Q = ρ × V × C P ×ΔT Where: Q - the heat exchange amount of the buried pipe, kW ρ—Density of water, kg / m 3 V—Volume flow rate of water, m 3 / s C P — Specific heat at constant pressure of water, kJ / (kg×℃) ΔT - the temperature difference between the inlet and outlet water temperatures of the test device, °C.

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