Cold and hot bidirectional rock-soil thermal response test system and control method thereof

Abstract

The invention discloses a cold and hot bidirectional rock-soil thermal response test system and a control method thereof. The system comprises a water storage part, an inner circulation part, an outer circulation part, a rock-soil collection part, a control part and an analysis part, the inner circulation part and the outer circulation part are respectively connected with the water storage part, and a thermoelectric refrigeration module for heating or refrigerating a water body is arranged in the inner circulation part; a detection part and a valve part are arranged in the inner circulation part and the outer circulation part; the detection part and the valve part are connected with the control part; the rock-soil collecting part is arranged along buried pipes with different depths in the buried heat exchanger; the analysis part is used for collecting and processing data of the acquisition part, the water body temperature and the operation time; the scheme supports a cold and hot bidirectional thermal response test, and the test result is closer to the annual actual operation condition of the ground source heat pump.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geothermal exploration and geotechnical engineering testing, and particularly relates to a cold-heat bidirectional geotechnical thermal response testing system and a control method thereof. BACKGROUND

[0002] In the development and utilization of ground source heat pump systems of shallow geothermal energy, accurately obtaining the thermal physical parameters (such as the thermal conductivity and the volumetric specific heat) of underground rock-soil is the key basis for system design and performance optimization. The traditional rock-soil thermal response testing (TRT) method for obtaining these parameters usually relies on fixedly installed equipment, and only through the constant heat injection of hot water circulation mode to the underground buried pipe for unidirectional heating, the thermal conductivity and volumetric specific heat of rock-soil are obtained by measuring the inlet and outlet water temperature and then inversion. However, this test method considering only a single heat injection mode has significant limitations, because the actual ground source heat pump system needs to alternately release cold load (in the cooling season) and heat load (in the heating season) to the underground in the whole year operation, and the thermal response characteristics of rock-soil to cold and heat two different working conditions are different. The unidirectional heat injection test method cannot accurately simulate and reflect the absorption and diffusion characteristics of underground rock-soil to cold load in actual operation, resulting in insufficient accuracy of system design according to the test results.

[0003] In addition, the traditional TRT system mostly adopts large fixed devices, and has single function, lacks integrated and portable design, and is time-consuming and laborious in field layout and use. At the same time, it has obvious short board in data acquisition, real-time analysis and intelligent diagnosis, and is difficult to obtain more rich test information and carry out deep analysis, and cannot meet the needs of current increasingly refined ground source heat pump system engineering design for accurate evaluation of rock-soil heat exchange capacity, especially actual heat exchange capacity under cold-heat alternating working conditions. SUMMARY

[0004] The present application aims at the above-mentioned deficiencies, and provides a cold-heat bidirectional geotechnical thermal response testing system and a control method thereof, which solves the problem that the existing TRT method cannot accurately obtain the thermal physical parameters of underground rock-soil in the whole year. At the same time, it solves the problem that the existing TRT system has single function, lacks integrated and portable design, and is time-consuming and laborious in use.

[0005] The present application is realized by the following scheme: A dual-mode geotechnical thermal response testing system includes a water storage section, an internal circulation section, an external circulation section, a geotechnical sampling section, a control section, and an analysis section. The internal and external circulation sections are connected to the water storage section, and the internal circulation section is equipped with a thermoelectric refrigeration module for heating or cooling the water. The internal and external circulation sections are equipped with a detection section and a valve section, both of which are connected to the control section. The geotechnical sampling section is installed along buried pipes at different depths in the buried heat exchanger. The analysis section collects and processes data from the sampling section, the water temperature, and the operating time.

[0006] Based on the structure of the above-mentioned bidirectional hot and cold geotechnical thermal response testing system, the internal circulation section includes a first inlet pipe, a first pump body, a thermoelectric cooling module, a first outlet pipe, and a heat exchange system; the inlet of the first pump body is connected to the first liquid inlet pipe, and the outlet pipe of the first pump body is connected to the first outlet pipe; the thermoelectric cooling module is disposed on the first outlet pipe; and the heat exchange system is in contact with the thermoelectric cooling module.

[0007] Based on the structure of the above-mentioned bidirectional thermal response testing system for soil and rock, the thermoelectric cooling module includes a first heat-conducting plate, a second heat-conducting plate, and a cooling plate assembly; the cooling plate assembly is disposed between the first heat-conducting plate and the second heat-conducting plate; plate heat exchangers are disposed on the end faces of the first heat-conducting plate and the second heat-conducting plate away from the cooling plate assembly; the first heat-conducting plate and the plate heat exchanger thereon are disposed in the first water outlet pipe, and the second heat-conducting plate and the plate heat exchanger thereon are disposed in the heat exchange system; the heat exchange system is an external direct current water source.

[0008] Based on the structure of the above-mentioned hot and cold bidirectional geotechnical thermal response testing system, the external circulation section includes a second outlet pipe, a second inlet pipe, and a second pump body; the second pump body is installed on the second outlet pipe, the second outlet pipe is connected to the inlet of the buried pipe heat exchanger, and the second inlet pipe is connected to the outlet of the buried pipe heat exchanger.

[0009] Based on the structure of the above-mentioned hot and cold bidirectional geotechnical thermal response testing system, a first temperature sensor, a first pressure gauge, a first flow sensor and a first flow regulating valve are provided at the connection between the second water outlet pipe and the buried pipe heat exchanger. A second temperature sensor, a second pressure gauge, a second flow sensor, and a second flow regulating valve are installed at the connection between the second water inlet pipe and the buried pipe heat exchanger.

[0010] Based on the structure of the above-mentioned bidirectional thermal response testing system for soil and rock, a third temperature sensor and a third flow sensor are also installed on the first water outlet pipe; the temperature and flow rate of the water outlet from the thermoelectric cooling module are detected by the third temperature sensor and the third flow sensor.

[0011] Based on the structure of the above-mentioned cold and hot two-way rock-soil thermal response test system, an electric heating device and a fourth temperature sensor are further arranged in the water storage part; the electric heating device is used to assist in heating the liquid in the water storage part in the heating mode, the fourth temperature sensor is used to directly detect the temperature of the water body in the water storage part, the first pump body is a small direct-current water pump, and the second pump body is a 200w micro centrifugal pump; the control part adopts a PLC or an embedded processor.

[0012] The present scheme provides a control method of a cold and hot two-way rock-soil thermal response test system, including the following steps: Step S1: selecting to start the heating mode or the cooling mode according to the actual working condition to be tested; Step S2: starting the inner circulation part and the outer circulation part according to the selected mode, using the rock-soil temperature in the rock-soil collection part, collecting the water temperature in the temperature collection part, and using the water flow in the flow collection part; Step S3: judging the steady-state time according to the running time or the water temperature change rate; Step S4: performing parameter inversion operation to generate the thermal conductivity and the thermal diffusivity results; Step S5: outputting the data curve and the analysis report to the display interface or the U disk; the data can also be uploaded to the cloud platform in a wireless mode, so as to facilitate remote viewing, comparative analysis and long-term storage; Step six: automatically turning off the system according to the task setting.

[0013] In step S1, the heating mode is selected, and the specific steps are as follows: Step S111: the fourth temperature sensor detects the water temperature in the water storage part, the second pump body is closed, and the first pump body is opened; at this time, the outer circulation part does not act; when the water temperature is less than a preset critical value A in the system, the electric heating device is started to heat the liquid in the water storage part, and the electric heating and cooling module heats the water in the inner circulation system; Step S112: when the water temperature is less than the critical value A, the electric heating device is closed, and the electric heating and cooling module is used for heating alone until the temperature detected by the fourth temperature sensor is consistent with the temperature detected by the second temperature sensor, and then the electric heating and cooling module stops heating; at this time, the water temperature heating is completed; the second pump body is started to perform the hot water external circulation operation; When the electric heating and cooling module works, the external water source continuously exchanges heat with the second heat exchange fin, so that the electric heating and cooling module can work more efficiently.

[0014] In step S1, the cooling mode is selected, and the specific steps are as follows: Step S121, the fourth temperature sensor detects the water temperature in the water storage part, the second pump body is closed, and the first pump body is opened; at this time, the outer circulation part does not act; the electric heating refrigeration module is started to refrigerate the water in the inner circulation system; Step S122, when the temperature detected by the fourth temperature sensor is consistent with the temperature detected by the second temperature sensor, the thermoelectric refrigeration module stops refrigeration; at this time, the water temperature refrigeration is completed; the second pump body is started to perform the cold water external circulation operation; When the electric heating refrigeration module works, the external water source continuously exchanges cold energy with the second heat exchange fin, so that the electric heating refrigeration module can work more efficiently. When the refrigeration mode is selected, the refrigeration medium is put into the water storage part.

[0015] In summary, due to the adoption of the above technical scheme, the beneficial effects of the present application are: 1, the water in the water storage part is heated or refrigerated by the thermoelectric refrigeration module in the inner circulation part according to the actual test requirement, and finally the water at the predetermined temperature is input to the ground heat exchanger, and after heat exchange with the soil in the ground heat exchanger, it is returned to the water storage part, the rock-soil collecting part dynamically monitors the temperature of the rock-soil body at different depths, and the control part is used for controlling and adjusting the water temperature, the valve opening time and the power source opening time; the analysis part automatically inverts the thermal conductivity and thermal diffusivity through the collected inlet and outlet water temperature, rock-soil temperature, flow rate, running time and other data, and outputs the test curve, and finally realizes efficient rock-soil thermal response test.

[0016] 2, the present application supports bidirectional thermal response test of cold and heat, and the test result is closer to the actual operation condition of the ground source heat pump all year round; 3, the thermoelectric refrigeration module in the present application has compact structure, can realize bidirectional energy transmission, and improves the test response efficiency; 4, the control system in the present application has high integration degree, realizes automatic inversion of parameters, real-time sensing of rock-soil temperature and automatic analysis and output of test results; 5, the structure in the present application is suitable for portable deployment and has the ability of rapid field test; 6, in the heating test mode, the cold face of the Peltier module absorbs the system heat load through the cold water circulation system, plays an effective "energy absorption" role, prevents local overheating, and maintains the stability of the hot end; 7, in the refrigeration test mode, the hot face of the Peltier module forms a closed water cooling loop with the hot water circulation system, which has better heat exchange efficiency and continuous operation capacity compared with the traditional air cooling structure. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 is the overall structure schematic diagram of the present application; Fig. 2 This is a schematic diagram of the thermoelectric refrigeration module in this invention; Reference numerals: 1. Water storage unit; 2. Internal circulation unit; 3. External circulation unit; 4. Control unit; 11. Electric heating device; 12. Fourth temperature sensor; 21. First water inlet pipe; 22. First pump body; 23. Thermoelectric cooling module; 24. First water outlet pipe; 25. Heat exchange system; 26. First heat conduction plate; 27. Second heat conduction plate; 28. Cooling plate assembly; 31. Second water outlet pipe; 32. Second water inlet pipe; 33. Second pump body; 241. Third temperature sensor; 242. Third flow sensor; 311. First temperature sensor; 312. First pressure gauge; 313. First flow sensor; 314. First flow regulating valve; 321. Second temperature sensor; 322. Second pressure gauge; 323. Second flow sensor; 324. Second flow regulating valve. Detailed Implementation

[0018] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0019] Any feature disclosed in this specification (including any appended claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0020] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a predetermined orientation, or be constructed and operated in a predetermined orientation. Therefore, they should not be construed as limitations on this invention.

[0021] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0022] Example 1 like Figs. 1-2 As shown, the present invention provides a technical solution: The application discloses a cold and hot bidirectional rock-soil heat response testing system which comprises a water storage part 1, an inner circulation part 2, an outer circulation part 3, a rock-soil collection part, a control part 4 and an analysis part, wherein the inner circulation part 2 and the outer circulation part 3 are connected with the water storage part 1, a thermoelectric refrigeration module 23 for heating or refrigerating water is arranged in the inner circulation part 2, a detection part and a valve part can be arranged in the inner circulation part 2 and the outer circulation part 3, the detection part and the valve part are connected with the control part 4, the rock-soil collection part is arranged along buried pipes at different depths in a buried heat exchanger, and the analysis part collects and processes data of the collection part, water temperature and running time.

[0023] According to the structure, water in the water storage part 1 is heated or refrigerated by the thermoelectric refrigeration module 23 in the inner circulation part 2 according to actual testing requirements, the water at a predetermined temperature is input into the buried heat exchanger, is returned to the water storage part 1 after heat exchange with soil in the buried pipe of the buried heat exchanger, the rock-soil collection part dynamically monitors rock-soil body temperatures at different depths, the control part 4 is used for controlling and adjusting water temperature, valve opening time and power source opening time, the analysis part automatically inverses the heat conductivity and the heat diffusion rate according to collected data such as inlet and outlet water temperature, rock-soil temperature, flow rate and running time, and outputs a testing curve, and finally the efficient rock-soil heat response testing is realized.

[0024] As an example, the inner circulation part 2 can comprise a first water inlet pipe 21, a first pump body 22, the thermoelectric refrigeration module 23, a first water outlet pipe 24 and a heat exchange system 25, the water inlet of the first pump body 22 is connected with the first water inlet pipe, the water outlet pipe of the first pump body 22 is connected with the first water outlet pipe 24, the thermoelectric refrigeration module 23 is arranged on the first water outlet pipe 24, and the heat exchange system 25 is in contact with the thermoelectric refrigeration module 23. The thermoelectric refrigeration module 23 can comprise a first heat conduction plate 26, a second heat conduction plate 27 and a refrigeration fin group 28, the refrigeration fin group 28 is arranged between the first heat conduction plate 26 and the second heat conduction plate 27, and plate heat exchangers are arranged on end faces of the first heat conduction plate 26 and the second heat conduction plate 27 and away from the refrigeration fin group 28. The first heat conduction plate 26 and the plate heat exchanger thereon are arranged in the first water outlet pipe 24, the second heat conduction plate 27 and the plate heat exchanger thereon are arranged in the heat exchange system 25, and the heat exchange system 25 can be a direct-current water source outside.

[0025] Based on the above structure, when the detection system requires hot water for detection, by controlling the current direction of the thermoelectric cooling module 23, the contact part between the cooling chip assembly 28 and the first heat-conducting plate 26 releases heat, and the liquid in the first water outlet pipe 24 is heated through the plate heat exchanger; at this time, the contact part between the cooling chip assembly 28 and the second heat-conducting plate 27 absorbs heat, and the cold energy of the second heat-conducting plate 27 and its plate heat exchanger can be removed by the external direct current water source, so as to avoid ice formation on the second heat-conducting plate 27, thereby affecting the overall heat exchange efficiency.

[0026] Conversely, when the detection system requires cold water for detection, by controlling the current direction of the thermoelectric cooling module 23, the contact part between the cooling chip assembly 28 and the first heat-conducting plate 26 absorbs heat, and the liquid in the first water outlet pipe 24 is cooled through the plate heat exchanger; at this time, the contact part between the cooling chip assembly 28 and the second heat-conducting plate 27 releases heat, and the heat of the second heat-conducting plate 27 and its plate heat exchanger can be removed by the external direct current water source, so as to avoid the temperature on the second heat-conducting plate 27 from being too high, thereby affecting the overall heat exchange efficiency.

[0027] This solution uses the change in current direction of the thermoelectric cooling module 23 to control the water flow on one side of the upper heat-conducting plate to raise or lower the temperature, thereby achieving heating / cooling functions respectively, accurately simulating the operation of a ground source heat pump under summer cooling load and winter heating load. In this solution, only one side of the thermoelectric cooling module 23 is used for heat exchange with the water circulation (i.e., the first heat-conducting plate 26), while the other side (the second heat-conducting plate 27) is used for heat dissipation or cold absorption. The heating and cooling functions are achieved by switching the current polarity, eliminating the need for physical switching of the heat exchange surface, thus improving system stability and compactness.

[0028] As an example, the cooling chip assembly 28 can consist of 24 cooling chips (4×6), which are attached to the upper and lower heat-conducting plates respectively to form a sandwich heat exchange structure; a plate heat exchanger is connected to the outside of the heat-conducting plates. A thermoelectric cooler is a semiconductor device manufactured based on the Peltier effect. When current passes through a PN junction composed of different types of semiconductor materials, heat is absorbed on one side and released on the other, thus regulating the temperature difference between the cold and hot ends. It features a compact structure, no moving parts, bidirectional heat exchange, and high response speed. A typical Peltier module, such as the TEC1-12709, contains 127 pairs of thermocouples, operates at approximately 12V, and has a maximum operating current of approximately 9A, making it suitable for low- to medium-power thermal management applications. One side of the module is attached to the cold source heat exchange surface (releasing cold energy), and the other side is attached to the hot source heat exchange surface (discharging heat). In this invention, multiple Peltier modules are sandwiched between upper and lower heat-conducting plates in a 4×6 array structure, forming a highly efficient sandwich heat exchange structure. The cold end is used for cooling in a chilled water system, and the hot end is used for auxiliary heating in a hot water system, forming a complementary cooling and heating cycle.

[0029] As an example, the outer circulation part 3 can include a second water outlet pipe 31, a second water inlet pipe 32 and a second pump body 33; the second pump body 33 is arranged on the second water outlet pipe 31, the second water outlet pipe 31 is connected with the water inlet of the ground pipe heat exchanger, and the second water inlet pipe 32 is connected with the water outlet of the ground pipe heat exchanger; A first temperature sensor 311, a first pressure gauge 312, a first flow sensor 313 and a first flow regulating valve 314 are arranged at the connection between the second water outlet pipe 31 and the ground pipe heat exchanger; A second temperature sensor 321, a second pressure gauge 322, a second flow sensor 323 and a second flow regulating valve 324 are arranged at the connection between the second water inlet pipe 32 and the ground pipe heat exchanger; Based on the above structure, the outer circulation part 3 circulates the water in the water storage part 1 to the ground pipe heat exchanger; the temperature sensor, the pressure sensor and the flow sensor are used to test the temperature, pressure and flow of the liquid entering and leaving the ground pipe heat exchanger, respectively, to provide data support for later detection, and the flow regulating valve is used to control the flow of the entire pipeline.

[0030] As an example, a third temperature sensor 241 and a third flow sensor 242 can also be arranged on the first water outlet pipe 24; the third temperature sensor 241 and the third flow sensor 242 are used to detect the temperature and flow of the water outlet by the thermoelectric refrigeration module 23.

[0031] As an example, an electric heating device 11 and a fourth temperature sensor 12 can also be arranged in the water storage part 1; the electric heating device 11 is used to assist in heating the liquid in the water storage part 1 in the heating mode, and the fourth temperature sensor 12 is used to directly detect the temperature of the water body in the water storage part 1, so that the later control is more flexible.

[0032] As an example, the first pump body 22 is a small direct-current water pump, and the second pump body 33 is a 200w micro centrifugal pump; the centrifugal pump can realize stepless frequency conversion, and can more flexibly provide power for the outer circulation part 3.

[0033] As an example, the control part 4 can adopt PLC or embedded processor, and the control part 4 integrates the power supply control of the thermoelectric refrigeration module 23, the start-stop control of the electric heating device 11, the flow temperature acquisition, the automatic switching of cold and hot working conditions, the electromagnetic valve control and data recording; the system has higher energy efficiency, longer module life and more comprehensive functions.

[0034] Embodiment 2 A control method of a cold-heat bidirectional geotechnical thermal response test system, comprising the following steps: Step S1: selecting to start a heating mode or a refrigeration mode according to an actual working condition to be tested; Step S2: Start the inner loop part 2 and the outer loop part 3 according to the selected mode, the rock-soil collection part adopts the rock-soil temperature, the temperature collection part collects the water temperature, and the flow collection part adopts the water flow; Step S3: Determine the steady state time according to the running time or the water temperature change rate; Step S4: Perform parameter inversion operation to generate the thermal conductivity and thermal diffusivity results; Step S5: Output the data curve and analysis report to the display interface or U disk; data can also be uploaded to the cloud platform through wireless means (such as Wi-Fi, 4G) for remote viewing, comparative analysis and long-term storage; Step six: automatically turn off the system according to the task setting.

[0035] In step S1, the heating mode is selected, and the specific steps are as follows: Step S111, the fourth temperature sensor 12 detects the water temperature in the water storage part 1, the second pump body 33 is closed, and the first pump body 22 is opened; At this time, the outer loop part 3 does not act; When the water temperature is less than the critical value A, the electric heating device 11 is started to heat the liquid in the water storage part 1, and the thermoelectric refrigeration module heats the water in the inner loop system; Step S112, when the water temperature is less than the critical value A, the electric heating device 11 is closed, and the thermoelectric refrigeration module is used for heating alone until the temperature detected by the fourth temperature sensor 12 and the temperature detected by the second temperature sensor 321 are consistent, and the thermoelectric refrigeration module 23 stops heating; At this time, the water temperature heating is completed; Start the second pump body 33 to perform hot water external circulation operation; When the thermoelectric refrigeration module is working, the external water source continuously exchanges heat with the second heat exchange fin, so that the thermoelectric refrigeration module can work more efficiently.

[0036] In step S1, the cooling mode is selected, and the specific steps are as follows: Step S121, the fourth temperature sensor 12 detects the water temperature in the water storage part 1, the second pump body 33 is closed, and the first pump body 22 is opened; At this time, the outer loop part 3 does not act; Start the thermoelectric refrigeration module to cool the water in the inner loop system; Step S122, when the temperature detected by the fourth temperature sensor 12 and the temperature detected by the second temperature sensor 321 are consistent, the thermoelectric refrigeration module 23 stops cooling; At this time, the water temperature cooling is completed; Start the second pump body 33 to perform cold water external circulation operation; When the thermoelectric refrigeration module is working, the external water source continuously exchanges heat with the second heat exchange fin, so that the thermoelectric refrigeration module can work more efficiently.

[0037] When the refrigeration mode is selected, a refrigeration medium such as ice can be put into the water storage part 1, so that the overall refrigeration efficiency can be improved.

[0038] Embodiment 3 The embodiment provides a more specific structure: A cold and hot two-way rock-soil heat response test system comprises: (1) Hot water preparation unit: comprising a built-in 10L hot water tank, connected to an external water source, and heated to a target temperature by a built-in electric heater; at the same time, the heat recovery of the hot end of the Peltier module forms an auxiliary heating path of the hot water tank, which is used for maintaining the water temperature or reducing the main heating energy consumption; (2) Cold water preparation unit: comprising a built-in 10L cold water tank, and connected to an external 200L ice storage tank through an interface, used for providing a continuous low-temperature cold source for the cold water tank, and adapting to the cold injection working condition requirement; (3) Peltier module array: composed of 4*6=24 pieces of refrigeration pieces, which are respectively pasted between the upper and lower heat-conducting plates to form a sandwich heat exchange structure; the outer side of the heat-conducting plate is connected with a plate heat exchanger; (4) Rock-soil temperature acquisition unit: a plurality of external temperature sensors are arranged and buried in different depths of the ground buried pipe, and are connected to the host system through a quick plug-in interface, so that the dynamic monitoring of the rock-soil body temperature is realized; (5) Water pump and valve control unit: used for cold and hot water circulation driving and loop switching, and controlling the flow rate in the range of 0.2~0.4L / s; (6) Control system: adopting PLC or embedded processor, integrated with Peltier (TEC) power supply control, electric heater start-stop, flow temperature acquisition, cold and hot working condition automatic switching, electromagnetic valve control and data recording; the system has higher energy efficiency, longer module life and more comprehensive functions.

[0039] (7) Data analysis and inversion module: built-in thermal physical property parameter inversion algorithm, through the collected inlet and outlet water temperature, rock-soil temperature, flow rate, running time and other data, the thermal conductivity and thermal diffusivity are automatically inverted, and the test curve is output.

[0040] In the scheme, the upper and lower heat-conducting plates are made of copper or anode aluminum, the surfaces are polished and coated with heat-conducting silicone grease, and the uniform thermal contact and structural stability are realized through the clamping and fixing of studs and disc springs.

[0041] In the scheme, the cold end of the Peltier (TEC) module is connected with the cold water circulation system to absorb heat in the heating mode, and the hot end is connected with the hot water tank to release heat; in the refrigeration mode, the hot end is connected with the hot water circulation system to absorb heat, and the cold end is connected with the cold water tank to release cold, so as to form a cold and hot complementary structure. The heat generated by the hot end can help the hot water tank to rise in temperature through the hot water heat exchanger.

[0042] In the scheme, the temperature probes of the geotechnical temperature acquisition unit are arranged at multiple positions in the depth direction of the underground heat exchange pipe, which is used to capture different deep temperature response characteristics, so as to improve the accuracy of the inversion algorithm.

[0043] The refrigeration / heat dual working mode of the scheme; (1) The core temperature control component of the device is the upper heat conduction plate, which is embedded with 24 industrial-grade thermoelectric refrigeration pieces (TEC modules). By switching the current direction, the refrigeration or heating mode can be realized.

[0044] (2) In the refrigeration mode, the thermoelectric module absorbs heat to cool the water flow, which is suitable for simulating cold water injection into the buried pipe for heat response test; (3) In the heating mode, the thermoelectric module releases heat to warm up the water, which is suitable for geothermal recharge test or high temperature injection simulation; (4) The temperature control mode switching is completed by the PID controller in cooperation with the TEC driving module. The PLC can provide manual or program setting interface externally.

[0045] II. Buried pipe heat exchange water circulation system; (1) The temperature-controlled water flows out of the water tank and successively flows through the flow sensor, temperature sensor, pressure gauge and other measurement units; (2) The water enters the U-shaped buried pipe heat exchanger and exchanges heat with the soil; (3) After heat exchange, the water flow returns to the water tank to form a closed loop water circulation, ensuring consistent continuous inflow and outflow; (4) The entire water circuit is driven by a 200W stepless frequency conversion water pump, and the flow is controlled at 0.2L / s (12L / min) recommended by the standard, with a maximum of 0.4L / s, meeting the "GBT 19409-2017" ground source heat pump system test standard; (5) Under this flow, according to the total refrigeration power of the system matched thermoelectric module; (6) In order to improve the refrigeration efficiency and response speed, the external water source is suggested to use pre-cooling mechanism, which can add ice or ice blocks to the water tank to control the water temperature at 8~10°C, thereby reducing the refrigeration burden and enhancing the constant temperature control accuracy.

[0046] III. Water tank-heat conduction plate closed loop temperature control system; (1) The 10L water tank is used for water storage and temperature control buffering, and is equipped with a temperature sensor for real-time monitoring; (2) The small direct current water pump pumps water into the upper heat conduction plate, and the water flows through the TEC module for heating or refrigeration treatment; (3) The outlet temperature sensor and flow sensor are located at the outlet of the heat conduction plate to provide the PID control signal; (4) The temperature-controlled water flows back to the water tank to form a stable closed loop. (5) To improve the heating capacity and starting speed, an electric heater is integrated in the water tank, which is synchronized with the TEC module to heat in the heating mode, especially suitable for low-temperature environment or rapid temperature rising working condition in winter; (6) The electric heater is controlled by PLC, and is automatically started and stopped according to the threshold value set by the water tank temperature sensor, to ensure the safety and energy saving of the system.

[0047] Four, the lower heat-conducting plate cooling system (hot end / cold end heat removal); (1) The lower heat-conducting plate is used to closely contact the hot end of the TEC module, to ensure efficient heat dissipation in refrigeration and to absorb the residual cold of the cold end to prevent icing in heating; (2) An external constant-pressure water source is provided to provide continuous cooling water flow, without the need for a circulating water tank; (3) The outlet end is connected with temperature and flow sensors to monitor the cooling efficiency and water source stability; (4) No pump is needed, and the system relies on constant-pressure water source for direct flow; (5) The system also supports subsequent extension of the water tank + pump closed-loop cooling mechanism for scenarios where tap water cannot be used.

[0048] Five, PLC and data acquisition and control system; (1) The system is provided with a PLC controller and a display screen, which integrates PID control algorithm, sensor data acquisition, manual adjustment and automatic operation mode; (2) All temperature / flow / pressure sensor signals are unified into the PLC, and are displayed in real time by the display module; (3) The user can set the target outlet water temperature to control the automatic start and stop of the electric heater and the TEC module; (4) The system reserves a wireless communication module interface, which can be connected to an upper computer or a cloud platform for remote data uploading, operation state monitoring and automatic alarm.

[0049] Six, overall application scope; The device is suitable for ground source heat pump system buried heat exchange response test, short-term soil thermal parameter inversion, heat exchange capacity verification and other test scenes, and has: (1) Bidirectional control of refrigeration and heating; (2) High-precision closed-loop temperature control capability; (3) Real-time data acquisition and remote control capability; (4) Modular structure, easy to move and expand; The device of the application is composed of two sets of functionally independent and mutually cooperative water circulation systems, which are respectively used for: 1. Temperature control circulation system (small water tank-upper heat-conducting plate-small water tank); This is a closed-loop internal circulation system, mainly responsible for accurate control of water temperature, and is the core path to realize bidirectional simulation of cold and hot; Water is pumped from the small water tank by a small water pump and flows through the inside of the upper heat-conducting plate. The upper heat-conducting plate is embedded with a thermoelectric refrigeration piece (Peltier module), which can heat or cool the water flow by adjusting the current direction. The water controlled by the heat-conducting plate is returned to the small water tank, forming a closed loop. The water circuit is equipped with temperature sensors (outlet) and flow sensors for PID control closed-loop adjustment. The temperature-controlled water circuit can quickly respond and stabilize the temperature, providing a constant temperature water source for the ground pipe injection. In heating mode, auxiliary electric heaters in the water tank can also be used to improve the heating rate and efficiency. The temperature control accuracy can be better than ±0.5°C, and the system supports 0.2~0.3L / s flow rate operation.

[0050] 2. Ground pipe circulation system (water tank-ground pipe-water tank).

[0051] This is an external open-loop / closed-loop circulation system that simulates the water injection process of underground heat exchange pipes in actual engineering. After temperature control, the water is driven by a variable frequency water pump and injected into a buried pipe with a depth of 100~200m from the water tank. The water returns to the water tank after heat exchange with the soil in the buried pipe, forming a large flow heat exchange circulation. The water circuit is equipped with inlet and outlet temperature sensors, pressure gauges, flow meters, etc. for data collection and thermal response analysis. The system supports setting the flow rate according to the "GBT 19409-2017" standard, generally 0.2L / s (12L / min). The water tank also serves as a temperature control buffer and buried water receiving function. If used for refrigeration testing, it is recommended that the external water source be pre-cooled (with ice) before entering the water tank to improve cooling efficiency and reduce Peltier load.

[0052] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A cold and hot bidirectional geotechnical thermal response test system, characterized in that: The utility model relates to a water storage part (1), internal circulation part (2), outer circulation part (3), rock and soil collection part, control part (4) and analysis part, the internal circulation part (2) and outer circulation part (3) are connected with water storage part (1) respectively, the internal circulation part (2) is provided with the thermoelectric refrigeration module (23) for heating or refrigeration to water body, the internal circulation part (2) and outer circulation part (3) are provided with detection part and valve part, detection part and valve part are connected with control part (4), and rock and soil collection part is along the buried pipe of buried heat exchanger in different depth setting, and analysis part carries out collection processing to the data of collection part, water temperature, operating time.

2. The hot and cold bidirectional geotechnical thermal response test system according to claim 1, characterized in that: The internal circulation part (2) includes first inlet pipe (21), first pump body (22), thermoelectric refrigeration module (23), first outlet pipe (24) and heat exchange system (25), the water inlet of first pump body (22) is connected with first inlet pipe, and the outlet pipe of first pump body (22) is connected with first outlet pipe (24), the thermoelectric refrigeration module (23) is arranged on first outlet pipe (24), and the heat exchange system (25) is in contact with thermoelectric refrigeration module (23).

3. The hot and cold bidirectional geotechnical thermal response test system according to claim 2, characterized in that: The thermoelectric refrigeration module (23) includes first heat conduction plate (26), second heat conduction plate (27) and refrigeration piece group (28), the refrigeration piece group (28) is arranged between first heat conduction plate (26) and second heat conduction plate (27), and the end face of first heat conduction plate (26) and second heat conduction plate (27) away from refrigeration piece group (28) is provided with plate heat exchanger, first heat conduction plate (26) and the plate heat exchanger on it are arranged in first outlet pipe (24), and second heat conduction plate (27) and the plate heat exchanger on it are arranged in heat exchange system (25), and heat exchange system (25) is the direct current water source of outside.

4. The hot and cold bidirectional geotechnical thermal response test system according to claim 3, characterized in that: The outer circulation part (3) includes second outlet pipe (31), second inlet pipe (32) and second pump body (33), the second pump body (33) is arranged on second outlet pipe (31), the second outlet pipe (31) is connected with the water inlet of buried pipe heat exchanger, and the second inlet pipe (32) is connected with the water outlet of buried pipe heat exchanger.

5. The hot and cold bidirectional geotechnical thermal response test system according to claim 4, characterized in that: The connecting place of second outlet pipe (31) and buried pipe heat exchanger is provided with first temperature sensor (311), first pressure gauge (312), first flow sensor (313) and first flow regulating valve (314), The connecting place of second inlet pipe (32) and buried pipe heat exchanger is provided with second temperature sensor (321), second pressure gauge (322), second flow sensor (323) and second flow regulating valve (324).

6. The hot and cold bidirectional geotechnical thermal response test system according to claim 5, characterized in that: Third temperature sensor (241) and third flow sensor (242) are also arranged on first outlet pipe (24), and the temperature and flow of water outlet by thermoelectric refrigeration module (23) are detected by third temperature sensor (241) and third flow sensor (242).

7. The hot and cold bidirectional geotechnical thermal response test system according to claim 6, characterized in that: The water storage part (1) is further provided with an electric heating device (11) and a fourth temperature sensor (12); the electric heating device (11) is used for assisting in heating the liquid in the water storage part (1) in the heating mode; the fourth temperature sensor (12) is used for directly detecting the temperature of the water body in the water storage part (1); the first pump body (22) is a small direct-current water pump; the second pump body (33) is a 200w micro centrifugal pump; and the control part (4) adopts a PLC or an embedded processor.

8. A control method of a cold and hot bidirectional geotechnical thermal response test system, characterized in that: The method comprises the following steps: Step S1: selecting a heating mode or a refrigeration mode according to an actual working condition to be tested; Step S2: starting the inner circulation part (2) and the outer circulation part (3) according to the selected mode; the rock-soil temperature is collected by the rock-soil collection part; the water temperature is collected by the temperature collection part; and the water flow is collected by the flow collection part; Step S3: judging a steady-state time according to a running time or a water temperature change rate; Step S4: performing parameter inversion operation to generate a thermal conductivity and a thermal diffusivity result; Step S5: outputting data curves and analysis reports to a display interface or a U disk; or uploading the data to a cloud platform in a wireless mode, so as to facilitate remote viewing, comparative analysis and long-term storage; Step S6: automatically turning off the system according to a task setting.

9. The control method according to claim 8, characterized by: In step S1, the heating mode is selected, and the specific steps are as follows: Step S111: the fourth temperature sensor (12) detects the water temperature in the water storage part (1); the second pump body (33) is closed; and the first pump body (22) is started; at this time, the outer circulation part (3) does not work; when the water temperature is less than a preset critical value A, the electric heating device (11) is started to heat the liquid in the water storage part (1); and the electric heating refrigeration module heats the water in the inner circulation system; Step S112: when the water temperature is less than the critical value A, the electric heating device (11) is closed; the electric heating refrigeration module is used for heating alone until the temperature detected by the fourth temperature sensor (12) is consistent with the temperature detected by the second temperature sensor (321); then the electric heating refrigeration module (23) stops heating; at this time, the water heating is completed; and the second pump body (33) is started to perform the hot water external circulation operation; When the electric heating refrigeration module works, the external water source continuously exchanges heat with the second heat exchange fin, so that the electric heating refrigeration module can work more efficiently.

10. The control method of claim 8, wherein: In step S1, the refrigeration mode is selected, and the specific steps are as follows: Step S121: the fourth temperature sensor (12) detects the water temperature in the water storage part (1); the second pump body (33) is closed; and the first pump body (22) is started; at this time, the outer circulation part (3) does not work; the electric heating refrigeration module is started to refrigerate the water in the inner circulation system; Step S122: when the temperature detected by the fourth temperature sensor (12) is consistent with the temperature detected by the second temperature sensor (321), the electric heating refrigeration module (23) stops refrigerating; at this time, the water refrigeration is completed; and the second pump body (33) is started to perform the cold water external circulation operation; When the electric heat refrigeration module is working, the external water source continuously exchanges cold energy with the second heat exchange sheet, so that the electric heat refrigeration module can work more efficiently. When the refrigeration mode is selected, the refrigeration medium is put into the water storage part (1).

Images