An in-situ measurement system and method for the operation performance of medium-deep geothermal ground heat exchangers

Abstract

The present invention discloses a measured system and method for the operation performance of medium-deep geothermal buried pipes. The system includes a medium-deep geothermal buried pipe unit, a heat source side water pump unit, a heat pump unit, a cooling side water pump unit, and a cooling tower unit. The method can quickly carry out the measured research on the operation performance of medium-deep geothermal buried pipes under multiple working conditions by manually adjusting the operation parameters of the medium-deep geothermal buried pipes after the holes of the medium-deep geothermal buried pipes are formed, and clarify the actual operation performance of the medium-deep geothermal buried pipes under different working conditions, including peak heat extraction capacity, heat extraction capacity adjustment performance, circulation resistance characteristics, heat pump unit heating performance, etc. Thus, the number of medium-deep geothermal buried pipes mined can be designed more reasonably in the design stage, avoiding the waste of construction costs caused by over-exploitation and also avoiding the attenuation of later operation performance caused by insufficient mining quantity, providing more powerful measured data support for the popularization and application of the medium-deep geothermal buried pipe heat pump heating technology.

Description

Technical Field

[0001] The present invention relates to a measurement system and method, and particularly to a measurement system and method for the operation performance of medium and deep geothermal buried pipes. Background Art

[0002] Compared with traditional geothermal energy utilization technologies, the medium and deep geothermal buried pipe heat pump heating technology has the advantages of high heat source temperature, large heat extraction amount, stable system operation, high performance, small floor area, protection of underground water resources, etc., and is not affected by ground climate conditions, and can realize the clean, efficient and continuous utilization of medium and deep geothermal energy. It is a more excellent high-efficiency heating technology for renewable energy.

[0003] However, when the medium and deep geothermal buried pipe heat pump technology is actually operating, its performance is affected by local geothermal conditions, which will in turn affect the project design scheme and the long-term operation performance of the system. Since the heat extraction point of the medium and deep geothermal buried pipe is relatively deep and the pipe length is also relatively long, usually 2000 - 3000 meters, the construction period of the medium and deep geothermal buried pipe is longer and the construction cost is higher compared with conventional heat sources. Therefore, in the design stage, in order to more reasonably design the exploitation data of the medium and deep geothermal buried pipe and formulate a more explicit and reasonable operation regulation strategy for the later actual operation, it is very necessary to conduct measurement research on the actual operation performance of newly built medium and deep geothermal buried pipes, especially the variable working condition operation performance; however, the existing technology lacks a test device or method for the actual operation performance of medium and deep geothermal buried pipes. Therefore, in order to clarify the geothermal regulation at the project location and the actual operation performance of medium and deep geothermal buried pipes, and timely optimize and adjust the design scheme to provide more powerful measured data support for the popularization and application of the medium and deep geothermal buried pipe heat pump heating technology, it is urgent to provide a measurement system and method for the operation performance of medium and deep geothermal buried pipes. Summary of the Invention

[0004] In order to solve the deficiencies of the above technologies, the present invention provides a measurement system and method for the operation performance of medium and deep geothermal buried pipes.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a measurement system for the operation performance of medium and deep geothermal buried pipes, including a medium and deep geothermal buried pipe unit, a heat source side water pump unit, a heat pump unit, a cooling side water pump unit, and a cooling tower unit; the medium and deep geothermal buried pipe unit is connected to the heat source side water pump unit at one end of the water outlet, the heat source side water pump unit is connected to the heat pump unit, and the heat pump unit is connected to the water inlet of the medium and deep geothermal buried pipe unit through a first return pipeline;

[0006] The heat pump unit is also connected to the cooling side water pump unit, the cooling side water pump unit is connected to the water inlet of the cooling tower unit, and the cooling tower unit is connected to the heat pump unit through a second return pipeline at the water outlet.

[0007] Furthermore, the medium-deep geothermal buried pipe unit contains one or more medium-deep geothermal buried pipes. The buried depth of each medium-deep geothermal buried pipe is 2 - 3 kilometers, and the medium-deep geothermal energy is extracted by means of a partition wall heat exchange method; when the circulating water volume of the heat extraction hole of a single medium-deep geothermal buried pipe is 20 - 30 m 3 / h, the outlet water temperature reaches above 30°C.

[0008] Furthermore, the heat source side water pump unit includes a variable frequency water pump with an adjustable water pump frequency of 25 - 50 Hz and a continuously adjustable water flow rate of 20 - 40 m 3 / h.

[0009] Furthermore, the heat pump unit adopts a high-efficiency electric-driven heat pump unit and a distribution system, including an evaporator, a compressor, a condenser, and an expansion valve.

[0010] Furthermore, the cooling side water pump unit contains a variable frequency water pump with an adjustable water pump frequency of 25 - 50 Hz and a continuously adjustable flow rate of 60 - 120 m 3 / h.

[0011] Furthermore, the cooling tower unit contains an open cooling tower that meets the conditions of a rated heat rejection of 600 kW and an adjustable fan frequency of 25 - 50 Hz.

[0012] Furthermore, temperature sensors are installed at the inlet and outlet of the medium-deep geothermal buried pipe, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit;

[0013] Pressure sensors are installed at the inlet and outlet of the medium-deep geothermal buried pipe, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit;

[0014] Flow sensors are installed on the inlet pipeline of the medium-deep geothermal buried pipe and the inlet distribution pipeline of the cooling tower;

[0015] Three-phase power sensors are installed at the compressor of the heat pump unit, the heat source side water pump, and the user side water pump.

[0016] Furthermore, the data monitoring and acquisition time step of the temperature sensor, pressure sensor, flow sensor, and three-phase power sensor is 1 min.

[0017] A measurement method for the actual operation performance of a medium-deep geothermal buried pipe system includes the following processes: After obtaining the operation data of each group of medium-deep geothermal buried pipes, quantitatively analyze the heat transfer performance of the medium-deep geothermal buried pipes with the change of operation parameters, quantitatively analyze the circulation resistance of the medium-deep geothermal buried pipes with the change of operation parameters, and quantitatively analyze the heating performance of the heat pump unit of the medium-deep geothermal buried pipes with the change of operation parameters, so as to guide the design and operation regulation of the medium-deep geothermal buried pipe system.

[0018] Furthermore, the processing method is as follows:

[0019] 1) Test of variable flow rate: By adjusting the operation frequency of the water pump on the heat source side or the opening degree of the valve on the heat source side, maintain the circulating flow rate on the heat source side at the set value; the adjustment range of the circulating flow rate is 20 - 40 m 3 / h;

[0020] 2) Test of variable inlet water temperature: By adjusting the set value of the outlet water temperature of the evaporator of the heat pump unit, maintain the inlet water temperature on the heat source side at the set value, and the set range of the inlet water temperature is 5 - 30 °C;

[0021] 3) Test of the outlet water temperature of the circulating water on the cooling side: The set value of the outlet water temperature of the circulating water on the condensing side of the heat pump unit is maintained at 45 °C. By adjusting the frequency of the water pump on the cooling side and the frequency of the fan of the cooling tower, maintain a 5 °C temperature difference, that is, the inlet water temperature on the condensing side of the heat pump unit is 40 °C;

[0022] For each working condition test, after the adjustment is completed, maintain continuous operation for 12 hours, and then carry out the next working condition test;

[0023] The specific operation data for testing are as follows:

[0024] 1.1. Obtain circulating water temperature data: During the test, use temperature sensors to continuously monitor and collect the circulating water temperatures at the inlet and outlet of the medium-deep geothermal buried pipes, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit. The data monitoring and collection step is 1 minute, and the operation data is stored;

[0025] 1.2. Obtain circulating pressure data: During the test, use pressure sensors to continuously monitor and collect the circulating water pressures at the inlet and outlet of the medium-deep geothermal buried pipes, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit. The data monitoring and collection step is 1 minute, and the operation data is stored;

[0026] 1.3. Obtain circulating flow rate data: During the test, use flow sensors to continuously monitor and collect the circulating flow rates of the inlet pipeline of the medium-deep geothermal buried pipes and the inlet distribution pipeline of the cooling tower. The data monitoring and collection step is 1 minute, and the operation data is stored;

[0027] 1.4. Obtain the operating power data: During the test, a three-phase power sensor is used to monitor and collect the operating powers of the compressor of the heat pump unit, the water pump on the heat source side, and the water pump on the user side in real time. The data monitoring and collection step size is 1 min, and the operating data is stored.

[0028] The quantitative analysis process is as follows:

[0029] 2.1. After obtaining the operating data of each group of the medium-deep geothermal buried pipes, a fitting formula for the heat extraction amount of the medium-deep geothermal buried pipes at different circulation flow rates and inlet temperatures is obtained by regression in combination with Formula 1, and a quantitative analysis is carried out on the change of the heat transfer performance of the medium-deep geothermal buried pipes with the operating parameters.

[0030] Q g = a + b·G g 2 + c·G g + d·T g，i 2 + e·T g，i + f·G g ·T g，i Formula 1

[0031] Among them, Q g is the heat extraction power of the medium-deep geothermal buried pipes, with the unit of kW; G g is the circulation flow rate of the medium-deep geothermal buried pipes, with the unit of m 3 / h; T g，i is the inlet temperature of the medium-deep geothermal buried pipes, with the unit of °C; a - f are all fitting coefficients;

[0032] 2.2. After obtaining the operating data of each group of the medium-deep geothermal buried pipes, a fitting formula for the circulation resistance of the medium-deep geothermal buried pipes at different circulation flow rates is obtained by regression in combination with Formula 2, and a quantitative analysis is carried out on the change of the circulation resistance of the medium-deep geothermal buried pipes with the operating parameters.

[0033]

[0034] Among them, ΔP g is the circulation resistance of the medium-deep geothermal buried pipes, with the unit of kPa; R e is the Reynolds number, a dimensionless parameter; H is the pipe depth of the medium-deep geothermal buried pipes, with the unit of m; D is the hydraulic diameter of the medium-deep geothermal buried pipes, with the unit of m; u is the circulation flow rate of the medium-deep geothermal buried pipes, with the unit of m / s; g is the gravitational constant, with the unit of m / s 2 ; i, j are all fitting coefficients;

[0035] 2.3. After obtaining the operation data of the heat pump unit, the fitting formula of the heating performance of the heat pump unit under different circulating flow rates, evaporator-side circulating water temperatures, and condenser-side circulating water temperatures is obtained by regression in combination with Formula 3-7, and the quantitative analysis of the heating performance of the medium-deep geothermal buried pipe heat pump unit with the change of operation parameters is carried out;

[0036]

[0037] t ce =t c -t e Formula 4

[0038]

[0039] DCOP = A·PLR 2 +B·PLR·t ce +C·t ce 2 +D·PLR+E·t ce +F Formula 6

[0040] COP = ICOP·DCOP Formula 7

[0041] Among them, ICOP represents the theoretical heating performance of the heat pump unit, a dimensionless parameter; DCOP represents the compressor efficiency of the heat pump unit, a dimensionless parameter; COP represents the actual heating performance of the heat pump unit, a dimensionless parameter; PLR represents the actual operating heating load ratio of the heat pump unit, a dimensionless parameter; t c represents the condensation temperature of the heat pump unit, unit K; t e represents the evaporation temperature of the heat pump unit, unit K; t ce represents the difference between the condensation temperature and the evaporation temperature of the heat pump unit, used to approximately characterize the compression ratio, unit K; Q c represents the actual heating capacity of the heat pump unit, unit kW; Q c，0 represents the rated heating capacity of the heat pump unit, unit kW; A - F are all fitting coefficients.

[0042] Furthermore, in the test of variable inlet water temperature, the outlet water temperature of the evaporator is adjusted according to the different water temperatures entering the evaporator, and by adjusting the compressor speed and the opening of the inlet guide vane valve, the outlet water temperature of the evaporator reaches the set value.

[0043] The present invention discloses a measured system and method for the operation performance of medium-deep geothermal buried pipes. By manually adjusting the operation parameters of the medium-deep geothermal buried pipes, including the inlet water temperature, circulation flow rate, start-stop mode, etc., after the medium-deep geothermal buried pipes are drilled, the measured research on the operation performance of the medium-deep geothermal buried pipes under multiple working conditions can be quickly carried out, and the actual operation performance of the medium-deep geothermal buried pipes under different working conditions can be clarified, including the peak heat extraction capacity, heat extraction capacity adjustment performance, circulation resistance characteristics, heat pump unit heating performance, etc.; thus, the number of medium-deep geothermal buried pipes exploited can be designed more reasonably in the design stage, avoiding the waste of construction costs caused by over-exploitation and also avoiding the attenuation of the later operation performance caused by insufficient exploitation quantity. At the same time, through the quantitative analysis of the heat extraction performance and circulation resistance characteristics of the medium-deep geothermal buried pipes under different operation conditions, and the quantitative analysis of the heating performance of the heat pump unit under different operation conditions, it also formulates a more explicit and reasonable operation control strategy for the actual operation of the project, especially for variable working conditions operation, and provides more powerful measured data support for the popularization and application of the medium-deep geothermal buried pipe heat pump heating technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the measured system for the operation performance of the medium-deep geothermal buried pipes of the present invention.

[0045] In the figure: 1, medium-deep geothermal buried pipe unit; 2, heat source side water pump unit; 3, heat pump unit; 4, cooling side water pump unit; 5, cooling tower unit; 6, first return pipeline; 7, second return pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0047] As Figure 1 shown, it is a system schematic diagram of the measured system for the operation performance of the medium-deep geothermal buried pipes of the present invention, including a medium-deep geothermal buried pipe unit 1, a heat source side water pump unit 2, a heat pump unit 3, a cooling side water pump unit 4, and a cooling tower unit 5; wherein, the medium-deep geothermal buried pipe unit 1 is connected to the heat source side water pump unit 2 at one end of the water outlet, the heat source side water pump unit 2 is connected to the heat pump unit 3, and the heat pump unit 3 is connected to the water inlet of the medium-deep geothermal buried pipe unit 1 through the first return pipeline 6;

[0048] The heat pump unit 3 is also connected to the cooling side water pump unit 4, the cooling side water pump unit 4 is connected to the water inlet of the cooling tower unit 5, and the cooling tower unit 5 is connected to the heat pump unit 3 through the second return pipeline 7 at the water outlet.

[0049] For the above-mentioned system of the measured system for the operation performance of the deep geothermal buried pipes, its overall design idea is:

[0050] a. The heat source side water pump unit 2 is used to drive the heat source water to circulate in the medium-deep geothermal buried pipe 1. The medium-deep geothermal buried pipe exchanges heat with the surrounding rock strata in the form of wall heat transfer to extract medium-deep geothermal energy, and then high-temperature heat source water can be obtained.

[0051] b. Based on the water circulation, by adjusting the water pump circulation flow rate on the heat source side, the test conditions of variable flow rate of the medium-deep geothermal buried pipe are simulated, and the adjustment range of the flow rate is 20 - 40m 3 / h.

[0052] c. The high-temperature heat source water after heat exchange at the medium-deep geothermal buried pipe 1 is pumped into the evaporator of the heat pump unit 3 by the heat source side water pump unit 2, and the heat is transferred to the refrigerant in the evaporator. After the high-temperature heat source water cools down, it leaves the evaporator of the heat pump unit 1 and re-enters the medium-deep geothermal buried pipe 1 through the first return pipeline 6 to extract medium-deep geothermal energy again, thus forming a cycle.

[0053] d. The heat pump unit sets the set value of the evaporator water temperature. According to the different water temperatures of the high-temperature heat source water entering the evaporator, by adjusting the compressor speed and the opening degree of the inlet guide vane valve in the heat pump unit, the actual outlet water temperature of the evaporator reaches the set value.

[0054] e. Based on the regulation and control of the water temperature, by adjusting the set value of the evaporator outlet water temperature, the test conditions of variable inlet water temperature of the medium-deep geothermal buried pipe are simulated.

[0055] f. The refrigerant in the evaporator of the heat pump unit absorbs heat from the high-temperature heat source water, flows through the compressor to the condenser, and transfers the heat to the circulating water on the cooling side; the cooled refrigerant flows through the expansion valve to the evaporator again to absorb the heat in the high-temperature heat source water again, thus forming a cycle.

[0056] g. After the circulating water on the cooling side absorbs the heat discharged by the refrigerant in the condenser, it flows through the cooling side water pump unit 4 to the cooling tower unit 5 for heat discharge, and the heat is discharged into the surrounding air; the circulating water on the cooling side after heat release flows back to the condenser of the heat pump unit 3 through the second return pipeline 7 to absorb heat again; thus, the entire heat transfer process is formed to realize the test and research on the operation performance of the medium-deep geothermal buried pipe.

[0057] Furthermore, for each component unit in the actual measurement system of the operation performance of the deep geothermal buried pipe, it is provided with:

[0058] The medium-deep geothermal buried pipe unit 3 contains one or more medium-deep geothermal buried pipes. The buried depth of each medium-deep geothermal buried pipe is 2500 meters, and the medium-deep geothermal energy is extracted by the partition wall heat transfer method; the circulating water volume of the heat extraction hole of a single medium-deep geothermal buried pipe is 20 - 30m 3When the flow rate is [X] m³ / h, the outlet water temperature can reach above 30 °C.

[0059] The water pump unit 2 on the heat source side includes a variable-frequency water pump with an adjustable water pump frequency of 25 - 50 Hz, which can achieve a continuously adjustable high-temperature heat source water flow rate of 20 - 40 m³ / h. 3 / h continuously adjustable.

[0060] The heat pump unit 3 adopts a high-efficiency electrically driven heat pump unit and a distribution system, including an evaporator, a compressor, a condenser, an expansion valve, etc.; when the high-efficiency electrically driven heat pump unit has a condensing side water supply temperature of 45 °C and an evaporating side outlet water temperature of 20 °C, the heating performance coefficient of the heat pump unit is as high as 7.80, and the heating performance coefficient of the heat pump heating device is as high as 6.46.

[0061] The water pump unit on the cooling side contains a variable-frequency water pump with an adjustable water pump frequency of 25 - 50 Hz, achieving a continuously adjustable flow rate of 60 - 120 m³ / h. 3 / h continuously adjustable.

[0062] The cooling tower unit contains an open cooling tower, meeting the condition of a rated heat rejection of 600 kW and an adjustable fan frequency of 25 - 50 Hz.

[0063] Moreover, to obtain the operation data of the medium-deep geothermal buried pipe during the test, the actual measurement system for the operation performance of the deep geothermal buried pipe is also designed with stable sensors, pressure sensors, flow sensors, and power sensors for data monitoring and collection. Specifically:

[0064] High-precision temperature sensors are installed at the inlet and outlet of the medium-deep geothermal buried pipe, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit. The high-precision temperature sensors have functions of automatic data collection, storage, and export. The temperature monitoring range is 0 - 100 °C, the collection accuracy is ≤ 0.1 °C, the data monitoring and collection time step is 1 min, and at least 1 month of operation data can be stored.

[0065] High-precision pressure sensors are installed at the inlet and outlet of the medium-deep geothermal buried pipe, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit. The high-precision pressure sensors have functions of automatic data collection, storage, and export. The pressure monitoring range is 0 - 10 MPa, the collection accuracy is ≤ 0.002 MPa, the data monitoring and collection time step is 1 min, and at least 1 month of operation data can be stored.

[0066] High-precision flow sensors are installed on the inlet pipeline of the medium-deep geothermal buried pipe and the inlet distribution pipeline of the cooling tower. The high-precision flow sensors have functions of automatic data collection, storage, and export. The flow monitoring range is 0 - 100 m³ / h. 3 / h, the acquisition accuracy ≤ 1%, the data monitoring and acquisition time step is 1 min, and at least 1 month of operation data can be stored.

[0067] High-precision three-phase power sensors are installed at the compressor, heat source side water pump, and user side water pump of the heat pump unit. The high-precision three-phase power sensors also have functions of automatic data acquisition, storage, and export. The power monitoring range is 0 - 200 kW, the acquisition accuracy ≤ 0.5%, the data monitoring and acquisition time step is 1 min, and at least 1 month of operation data can be stored.

[0068] As Figure 1 shown, in the figure represents the temperature measurement point, and the temperature measurement point represents that a high-precision temperature sensor is installed; represents the pressure measurement point, and the pressure measurement point represents that a high-precision pressure sensor is installed; represents the water flow measurement point, and the water flow measurement point represents that a high-precision flow sensor is installed; represents the electric power measurement point, and the electric power measurement point represents that a three-phase power sensor is installed.

[0069] In addition, for facilitating the control of the opening or closing state of the connecting pipelines of each unit, or the flow control of the heat source side water pump and the cold source side water pump, as Figure 1 shown, valves A, B, C, and D are provided.

[0070] Thus, for the in-situ measurement system of the operation performance of the medium-deep geothermal buried pipe disclosed by the present invention, the in-situ measurement method for the overall device is as follows:

[0071] 1) Measurement of variable flow rate of the medium-deep geothermal buried pipe: By adjusting the operating frequency of the heat source side water pump or the opening degree of the heat source side valve (i.e., Figure 1 valve C in 3 ), the circulating flow rate on the heat source side is maintained at the set value; the adjustment range of the circulating flow rate is 20 - 40 m 3 / h, and working conditions such as 20 m 3 / h, 25 m 3 / h, 30 m 3 / h, 35 m 3 / h, etc. are usually selected;

[0072] 2) Measurement of variable inlet water temperature of the medium-deep geothermal buried pipe: By adjusting the set value of the outlet water temperature of the evaporator of the heat pump unit, the inlet water temperature on the heat source side is maintained at the set value. The set range of the inlet water temperature is 5 - 30 °C, and working conditions such as 5 °C, 10 °C, 15 °C, 20 °C, etc. are usually selected; the adjustment of the outlet water temperature of the evaporator is based on the different water temperatures entering the evaporator, and by adjusting the compressor speed and the opening degree of the inlet guide vane valve, the outlet water temperature of the evaporator reaches the set value;

[0073] 3) Testing the outlet water temperature of the cooling side circulating water: The set value of the outlet water temperature of the circulating water on the condensing side of the heat pump unit is maintained at 45°C. By adjusting the frequency of the cooling side water pump and the frequency of the cooling tower fan, a 5°C temperature difference is maintained, that is, the inlet water temperature on the condensing side of the heat pump unit is 40°C;

[0074] For each working condition test, after the adjustment is completed, continuous operation is maintained for 12 hours, and then the next working condition test is carried out;

[0075] The specific operating data for the test are as follows:

[0076] 1.1. Obtaining circulating water temperature data: During the test, a temperature sensor is used to continuously monitor and collect the circulating water temperatures at the inlet and outlet of the medium-deep geothermal buried pipe, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit. The data monitoring and collection step size is 1 minute, and the operating data is stored;

[0077] 1.2. Obtaining circulating pressure data: During the test, a pressure sensor is used to continuously monitor and collect the circulating water pressures at the inlet and outlet of the medium-deep geothermal buried pipe, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit. The data monitoring and collection step size is 1 minute, and the operating data is stored;

[0078] 1.3: Obtaining circulating flow rate data: During the test, a flow sensor is used to continuously monitor and collect the circulating flow rates of the inlet pipeline of the medium-deep geothermal buried pipe and the inlet distribution pipeline of the cooling tower. The data monitoring and collection step size is 1 minute, and the operating data is stored;

[0079] 1.4. Obtaining operating power data: During the test, a three-phase power sensor is used to continuously monitor and collect the operating powers of the compressor of the heat pump unit, the water pump on the heat source side, and the water pump on the user side. The data monitoring and collection step size is 1 minute, and the operating data is stored;

[0080] The process of quantitative analysis is as follows:

[0081] 2.1. After obtaining the operating data of each group of medium-deep geothermal buried pipes, the fitting formula for the heat extraction of the medium-deep geothermal buried pipes at different circulating flow rates and inlet water temperatures is obtained by regression in combination with Formula 1, so as to realize the quantitative analysis of the heat transfer performance of the medium-deep geothermal buried pipes changing with operating parameters, and guide the design and operation regulation of the medium-deep geothermal buried pipe system;

[0082] Q g = a + b·G g 2 + c·G g + d·T g，i 2 + e·Tg，i +f·G g ·T g，i Formula 1

[0083] Among them, Q g is the heat extraction power of the medium-deep geothermal buried pipe, with the unit of kW; G g is the circulating flow rate of the medium-deep geothermal buried pipe, with the unit of m 3 / h; T g，i is the inlet water temperature of the medium-deep geothermal buried pipe, with the unit of °C; a - f are all fitting coefficients;

[0084] 2.2. After obtaining the operating data of each group of medium-deep geothermal buried pipes, the fitting formula of the circulating resistance of the medium-deep geothermal buried pipe under different circulating flow rates is regressed in combination with Formula 2, so as to realize the quantitative analysis of the change of the circulating resistance of the medium-deep geothermal buried pipe with the operating parameters, and guide the design and operation regulation of the medium-deep geothermal buried pipe system;

[0085]

[0086] Among them, ΔP g is the circulating resistance of the medium-deep geothermal buried pipe, with the unit of kPa; R e is the Reynolds number, a dimensionless parameter; H is the pipe depth of the medium-deep geothermal buried pipe, with the unit of m; D is the hydraulic diameter of the medium-deep geothermal buried pipe, with the unit of m; u is the circulating flow rate of the medium-deep geothermal buried pipe, with the unit of m / s; g is the gravitational constant, with the unit of m / s 2 ; i, j are all fitting coefficients;

[0087] 2.3. After obtaining the operating data of the heat pump unit, the fitting formula of the heating performance of the heat pump unit under different circulating flow rates, evaporation-side circulating water temperature and condensation-side circulating water temperature is regressed in combination with Formulas 3 - 7, so as to realize the quantitative analysis of the change of the heating performance of the medium-deep geothermal buried pipe heat pump unit with the operating parameters, and guide the design and operation regulation of the medium-deep geothermal buried pipe system;

[0088]

[0089] t ce =t c -t e Formula 4

[0090]

[0091] DCOP=A·PLR 2 +B·PLR·t ce +C·t ce 2 +D·PLR+E·t ce +F Formula 6

[0092] COP = ICOP·DCOP Formula 7

[0093] Wherein, ICOP represents the theoretical heating performance of the heat pump unit, a dimensionless parameter; DCOP represents the compressor efficiency of the heat pump unit, a dimensionless parameter; COP represents the actual heating performance of the heat pump unit, a dimensionless parameter; PLR represents the actual operating heating load ratio of the heat pump unit, a dimensionless parameter; t c represents the condensation temperature of the heat pump unit, in unit K; t e represents the evaporation temperature of the heat pump unit, in unit K; t ce represents the difference between the condensation temperature and the evaporation temperature of the heat pump unit, used to approximately characterize the compression ratio, in unit K; Q c represents the actual heating capacity of the heat pump unit, in unit kW; Q c，0 represents the rated heating capacity of the heat pump unit, in unit kW; A - F are all fitting coefficients.

[0094] Therefore, for the in - situ measurement system of the operation performance of the medium - deep geothermal buried pipe disclosed in the present invention, after the overall setup is completed, it is built on a mobile trolley. By building a mobile in - situ measurement platform for the operation performance of the medium - deep geothermal buried pipe, it greatly facilitates the in - situ measurement and processing of the performance of the medium - deep geothermal buried pipe. This in - situ measurement system for the operation performance of the medium - deep geothermal buried pipe can, by manually adjusting the operation parameters of the medium - deep geothermal buried pipe, including the inlet water temperature, circulation flow rate, start - stop mode, etc., quickly carry out the in - situ measurement research on the operation performance of the medium - deep geothermal buried pipe under multiple working conditions after the medium - deep geothermal buried pipe is drilled, and clarify the actual operation performance of the medium - deep geothermal buried pipe under different working conditions, including the peak heat extraction capacity, heat extraction capacity adjustment performance, circulation resistance characteristics, heating performance of the heat pump unit, etc.; thus, in the design stage, more reasonably design the number of medium - deep geothermal buried pipes exploited, avoid the waste of construction costs caused by over - exploitation, and also avoid the attenuation of the later operation performance caused by insufficient exploitation quantity. At the same time, through the quantitative analysis of the heat extraction performance and circulation resistance characteristics of the medium - deep geothermal buried pipe under different operation conditions, and the quantitative analysis of the heating performance of the heat pump unit under different operation conditions, it also formulates a more explicit and reasonable operation control strategy for the actual operation of the project, especially for variable - condition operation, and provides more powerful in - situ measurement data support for the popularization and application of the medium - deep geothermal buried pipe heat pump heating technology.

[0095] The above - mentioned embodiments are not limitations on the present invention, and the present invention is not limited to the above examples either. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present invention also fall within the protection scope of the present invention.

Claims

1. A measurement method for the actual operation performance of a medium-deep geothermal buried pipe system, characterized in that: The processing procedure of the actual measurement method is as follows: 1) Variable flow rate test: By adjusting the operating frequency of the pump on the heat source side or the opening degree of the valve on the heat source side, maintain the circulating flow rate on the heat source side at the set value; the adjustment range of the circulating flow rate is 20 - 40 m 3 / h; 2) Test of varying the inlet water temperature: By adjusting the set value of the outlet water temperature of the evaporator of the heat pump unit, the inlet water temperature on the heat source side is maintained at the set value, and the set range of the inlet water temperature is 5 - 30°C; 3) Test of the outlet water temperature of the circulating water on the cooling side: The set value of the outlet water temperature of the circulating water on the condensing side of the heat pump unit is maintained at 45°C. By adjusting the frequency of the cooling side water pump and the frequency of the fan of the cooling tower, a 5°C temperature difference is maintained, that is, the inlet water temperature on the condensing side of the heat pump unit is 40°C; Among them, the quantitative analysis process is as follows: 2.

1. After obtaining the operating data of each group of the medium - deep geothermal buried pipes, combined with Formula 1, a fitting formula for the heat extraction of the medium - deep geothermal buried pipes at different circulating flow rates and inlet water temperatures is regressed, and a quantitative analysis is carried out on the change of the heat transfer performance of the medium - deep geothermal buried pipes with the operating parameters; Formula 1, Among them, Q g is the heat extraction power of the medium-deep geothermal buried pipe, with the unit of kW; G g is the circulation flow rate of the medium-deep geothermal buried pipe, with the unit of m 3 / h; T g,i is the inlet water temperature of the medium-deep geothermal buried pipe, with the unit of °C; a -f are all fitting coefficients; 2.

2. After obtaining the operating data of each group of the medium - deep geothermal buried pipes, combined with Formula 2, a fitting formula for the circulating resistance of the medium - deep geothermal buried pipes at different circulating flow rates is regressed, and a quantitative analysis is carried out on the change of the circulating resistance of the medium - deep geothermal buried pipes with the operating parameters; Formula 2, Among them, is the circulating resistance of the medium-deep geothermal buried pipe, with the unit of kPa; R e is the Reynolds number, a dimensionless parameter; H is the depth of the medium-deep geothermal buried pipe, with the unit of m; D is the hydraulic diameter of the medium-deep geothermal buried pipe, with the unit of m; u is the circulating flow rate of the medium-deep geothermal buried pipe, with the unit of m / s; g is the gravitational constant, with the unit of m / s 2 ; i , j are both fitting coefficients; 2.

3. After obtaining the operating data of the heat pump unit, combined with Formulas 3 - 7, a fitting formula for the heating performance of the heat pump unit at different circulating flow rates, the circulating water temperature on the evaporation side, and the circulating water temperature on the condensing side is regressed, and a quantitative analysis is carried out on the change of the heating performance of the medium - deep geothermal buried pipe heat pump unit with the operating parameters; Formula 3, Formula 4, Formula 5, Formula 6, Formula 7, Among them, ICOP represents the theoretical heating performance of the heat pump unit, a dimensionless parameter; DCOP represents the compressor efficiency of the heat pump unit, a dimensionless parameter; COP represents the actual heating performance of the heat pump unit, a dimensionless parameter; PLR represents the actual operating heating load ratio of the heat pump unit, a dimensionless parameter; t c represents the condensation temperature of the heat pump unit, in units of K; t e represents the evaporation temperature of the heat pump unit, in units of K; t ce represents the difference between the condensation temperature and the evaporation temperature of the heat pump unit, used to approximately characterize the compression ratio, in units of K; Q c represents the actual heating capacity of the heat pump unit, in units of kW; Q c,0 represents the rated heating capacity of the heat pump unit, in units of kW; A - F are all fitting coefficients.

2. The measurement method of the in-situ measurement system for the operation performance of medium-deep geothermal buried pipes according to claim 1, characterized in that: For each working condition test, after the adjustment is completed, continuous operation is maintained for 12 hours, and then the next working condition test is carried out; the specific operating data for the test are as follows: 1.

1. Obtain circulating water temperature data: During the test process, a temperature sensor is used to monitor and collect the circulating water temperatures at the inlet and outlet of the medium - deep geothermal buried pipes, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit in real - time. The data monitoring and collection step size is 1 min, and the operating data is stored; 1.

2. Obtain circulating pressure data: During the test process, a pressure sensor is used to monitor and collect the circulating water pressures at the inlet and outlet of the medium - deep geothermal buried pipes, the inlet and outlet of the cooling tower, the inlet and outlet of the evaporator of the heat pump unit, and the inlet and outlet of the condenser of the heat pump unit in real - time. The data monitoring and collection step size is 1 min, and the operating data is stored; 1.

3. Obtain circulating flow rate data: During the test process, a flow sensor is used to monitor and collect the circulating flow rates of the inlet pipeline of the medium - deep geothermal buried pipes and the inlet distribution pipeline of the cooling tower in real - time. The data monitoring and collection step size is 1 min, and the operating data is stored; 1.

4. Obtain operating power data: During the test process, a three - phase power sensor is used to monitor and collect the operating powers of the compressor of the heat pump unit, the water pump on the heat source side, and the water pump on the user side in real - time. The data monitoring and collection step size is 1 min, and the operating data is stored.

3. The measurement method of the in-situ measurement system for the operation performance of medium-deep geothermal buried pipes according to claim 2, characterized in that: In the test of 2) varying the inlet water temperature, according to the different water temperatures entering the evaporator, the outlet water temperature of the evaporator is adjusted by adjusting the compressor speed and the opening degree of the inlet guide vane valve to make the actual outlet water temperature of the evaporator reach the set value.

4. The measurement method of the in-situ measurement system for the operation performance of medium-deep geothermal buried pipes according to claim 3, characterized in that: The measured system includes a medium-deep geothermal buried pipe unit (1), a heat source side water pump unit (2), a heat pump unit (3), a cooling side water pump unit (4), and a cooling tower unit (5); the medium-deep geothermal buried pipe unit (1) is connected to the heat source side water pump unit (2) at one end of the water outlet, the heat source side water pump unit (2) is connected to the heat pump unit (3), and the heat pump unit (3) is connected to the water inlet of the medium-deep geothermal buried pipe unit (1) through a first return pipeline (6). The heat pump unit (3) is also connected to the cooling side water pump unit (4), the cooling side water pump unit (4) is connected to the water inlet of the cooling tower unit (5), and the cooling tower unit (5) is connected to the heat pump unit (3) through a second return pipeline (7) at the water outlet. The heat source side water pump unit (2) includes a variable frequency water pump, the water pump frequency is adjustable from 25 to 50 Hz, and the water flow rate is continuously adjustable from 20 to 40 m 3 / h.

5. The measurement method of the in-situ measurement system for the operation performance of medium-deep geothermal buried pipes according to claim 4, characterized in that: The medium-deep geothermal buried pipe unit (1) includes one or more medium-deep geothermal buried pipes. The buried depth of each medium-deep geothermal buried pipe is 2 - 3 kilometers, and the medium-deep geothermal energy is extracted by means of a partition wall heat exchange method; when the circulating water volume of the heat extraction hole of a single medium-deep geothermal buried pipe is 20 - 30 m 3 / h, the outlet water temperature reaches above 30°C.

6. The measurement method of the in-situ measurement system for the operation performance of medium-deep geothermal buried pipes according to claim 5, characterized in that: The heat pump unit (3) adopts a high-efficiency electric-driven heat pump unit and a distribution system, including an evaporator, a compressor, a condenser, and an expansion valve.

7. The measurement method of the in-situ measurement system for the operation performance of medium-deep geothermal buried pipes according to claim 6, characterized in that: The cooling-side water pump unit (4) includes a variable-frequency water pump, the frequency of the water pump is adjustable from 25 to 50 Hz, and the water flow rate is continuously adjustable from 60 to 120 m 3 / h.

8. The measurement method of the in-situ measurement system for the operation performance of medium-deep geothermal buried pipes according to claim 7, characterized in that: The cooling tower unit (5) contains an open cooling tower, meeting the conditions of a rated heat rejection of 600 kW and an adjustable fan frequency of 25 - 50 Hz.

9. The measurement method of the in-situ measurement system for the operation performance of medium-deep geothermal buried pipes according to claim 4 or 8, characterized in that: Temperature sensors are installed at the water inlets and outlets of the medium-deep geothermal buried pipes, the water inlets and outlets of the cooling tower, the water inlets and outlets of the heat pump unit evaporator, and the water inlets and outlets of the heat pump unit condenser. Pressure sensors are installed at the water inlets and outlets of the medium-deep geothermal buried pipes, the water inlets and outlets of the cooling tower, the water inlets and outlets of the heat pump unit evaporator, and the water inlets and outlets of the heat pump unit condenser. Flow sensors are installed on the inlet pipeline of the medium-deep geothermal buried pipes and the inlet distribution pipeline of the cooling tower. Three-phase power sensors are installed at the compressor of the heat pump unit, the heat source side water pump, and the user side water pump.

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