A device for testing heat exchange capacity of a ground source heat pump buried pipe

Abstract

The utility model relates to a kind of ground source heat pump buried pipe heat exchange capacity testing device, belong to ground source heat pump test field.The utility model described a kind of ground source heat pump buried pipe heat exchange capacity testing device including buried pipe heat exchanger, air source hot and cold water unit, water inlet pipeline, water outlet pipeline, water inlet pipeline is sequentially provided with first valve, buffer water tank, circulating water pump, electric heater, second valve and flow sensor according to the flow direction of water flow, water outlet pipeline is sequentially provided with first pressure sensor, first temperature sensor and third valve according to the flow direction of water flow, water outlet pipeline and water inlet management between still being provided with first bypass valve, second bypass valve.This device can carry out ground source heat pump buried hole summer, winter operating condition test, can also meet the heat exchange test requirement of buried pipe of different depth, improve the accuracy of test area soil thermal physical property parameter.

Description

Technical Field

[0001] This utility model relates to the field of ground source heat pump testing technology, specifically a ground source heat pump buried pipe heat exchange capacity testing device. Background Technology

[0002] Geothermal energy is thermal energy stored within the Earth. It is a clean, low-carbon, widely distributed, abundant, safe, and high-quality renewable energy source. Geothermal energy development and utilization features a continuous and stable energy supply, high efficiency, and renewability. Geothermal energy resource development and utilization methods include hydrothermal geothermal energy utilization systems, shallow buried pipe heat exchanger systems, and medium-deep non-intrusive heat exchanger systems.

[0003] The ground source heat pump system is a highly efficient, energy-saving, and environmentally friendly heating (cooling) system that uses a buried pipe heat exchanger to extract heat from shallow soil resources. It is currently the most environmentally friendly and efficient cooling and heating method available.

[0004] The site conditions and shallow geothermal energy resources are prerequisites for the application of a buried pipe ground source heat pump system. Before designing the ground source heat pump system, a certain number of test wells should be selected based on the on-site survey to test the thermal properties of the soil and rock, obtaining the heat transfer capacity parameters of the geological body at the project site. This provides accurate design parameters and basis for the subsequent design of the ground source heat pump system. In the early stages of ground source heat pump system application, the design depth of buried wells was generally 150 meters or less. With social development and technological progress, the current design depth of buried wells has exceeded 200 meters, and research has begun on deeper depths of 300 to 400 meters.

[0005] Currently, most geothermal thermal property testing instruments on the market obtain geothermal parameters by simulating summer operating conditions and using them as the basis for ground source heat pump system design. Few simulations are conducted for winter operating conditions. If the impact of different winter and summer operating conditions is not considered, and only summer test results are used as the design standard, the actual ground source heat pump system may not be able to match the different load demands of winter and summer. This could result in excessive system capacity waste or failure to meet the load requirements of the actual building. Long-term operation could lead to thermal or cold accumulation in the underground soil, affecting the performance efficiency of the heat pump system and compromising its energy-saving capabilities. Furthermore, the testing capabilities of currently available thermal property testing instruments are limited to depths below 200 meters, which cannot meet the requirements for testing the heat exchange capacity of deeper buried boreholes.

[0006] Based on this, the present utility model is proposed. Utility Model Content

[0007] In view of this, the purpose of this utility model is to address the above-mentioned problems by providing a reasonably designed and easy-to-operate system that can not only perform summer operation tests of ground source heat pump buried boreholes, but also meet the winter operation test requirements, and can also meet the heat exchange test requirements of buried pipes at different depths, thus providing strong support for the design of buried pipe ground source heat pumps.

[0008] This utility model provides a testing device for the heat exchange capacity of buried pipes in ground source heat pumps, the technical solution of which is as follows:

[0009] A ground source heat pump buried pipe heat exchange capacity testing device includes a buried pipe heat exchanger, an air source chiller / hot water unit, an inlet pipe connected to the buried pipe heat exchanger, and an outlet pipe connected to the buried pipe heat exchanger. The inlet pipe is connected to the outlet end of the air source chiller / hot water unit, and the outlet pipe is connected to the inlet end of the air source chiller / hot water unit. The inlet pipe is sequentially equipped with a first valve, a buffer tank, a circulating water pump, an electric heater, a second valve, and a flow sensor according to the water flow direction. One end of the first valve is connected to the outlet end of the air source chiller / hot water unit, and the other end is connected to the buffer tank. The input end of the circulating water pump is connected to the buffer tank. The output end of the circulating water pump is connected to one end of the electric heater, and the other end of the electric heater is connected to the first end of the second valve. A first pressure sensor, a first temperature sensor, and a third valve are sequentially installed on the outlet pipe according to the water flow direction. The first end of the third valve is connected to the inlet end of the air-source chiller / hot water unit. A first bypass valve and a second bypass valve are also installed between the outlet pipe and the inlet pipe. One end of the first bypass valve is connected to the first end of the third valve, and the other end of the first bypass valve is connected to the first end of the second valve. One end of the second bypass valve is connected to the inlet end of the air-source chiller / hot water unit, and the other end of the second bypass valve is connected to the input end of the circulating water pump.

[0010] As a further embodiment of this utility model, the circulating water pump is a variable frequency circulating water pump.

[0011] As a further embodiment of this invention, the air source chiller / hot water unit is driven and controlled by a variable frequency motor.

[0012] As a further embodiment of this utility model, the first valve, the second valve, and the third valve are all steel ball valves.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] The ground source heat pump buried pipe heat exchange capacity testing device can not only test the summer operation conditions of the buried ground source heat pump, but also meet the winter operation conditions test. At the same time, it can also meet the heat exchange test requirements of buried pipes at different depths, improve the accuracy of soil thermal property parameters in the test area, provide stronger support for the design of buried pipe ground source heat pumps, and avoid the phenomenon of thermal accumulation or cold accumulation in the underground soil during long-term operation of the designed and constructed ground source heat pump system, thus avoiding affecting the performance efficiency of the heat pump system. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a ground source heat pump buried pipe heat exchange capacity testing device. Detailed Implementation

[0016] The present invention will be described in detail below with reference to specific embodiments. These embodiments are merely some, not all, implementations of the present invention. All other implementations obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] Example 1

[0018] like Figure 1 As shown, a ground source heat pump buried pipe heat exchange capacity testing device includes a buried pipe heat exchanger 1, an air source chiller / hot water unit 13, an inlet pipe connected to the buried pipe heat exchanger 1, and an outlet pipe connected to the buried pipe heat exchanger 1. The inlet pipe is connected to the outlet end of the air source chiller / hot water unit 13, and the outlet pipe is connected to the inlet end of the air source chiller / hot water unit 13. The inlet pipe is sequentially equipped with a first valve 12, a buffer tank 11, a circulating water pump 9, an electric heater 8, a second valve 3, and a flow sensor 2, arranged according to the water flow direction. One end of the first valve 12 is connected to the outlet end of the air source chiller / hot water unit 13, and the other end of the first valve 12 is connected to the buffer tank 11. The input end of the circulating water pump 9 is connected to the buffer tank 11. The output end of the circulating water pump 9 is connected to one end of the electric heater 8, and the other end of the electric heater 8 is connected to the first end of the second valve 3. A first pressure sensor 5, a first temperature sensor 6, and a third valve 4 are sequentially arranged on the outlet pipe according to the direction of water flow. The first end of the third valve 4 is connected to the inlet end of the air source chiller / hot water unit 13. A first bypass valve 7 and a second bypass valve 10 are also arranged between the outlet pipe and the inlet pipe. One end of the first bypass valve 7 is connected to the first end of the third valve 4, and the other end of the first bypass valve 7 is connected to the first end of the second valve 3. One end of the second bypass valve 10 is connected to the inlet end of the air source chiller / hot water unit 13, and the other end of the second bypass valve 10 is connected to the input end of the circulating water pump 9.

[0019] In this example, the circulating water pump 9 is a variable frequency circulating water pump. The air source chiller / hot water unit 13 is driven and controlled by a DC variable frequency motor. The first valve 12, the second valve 3, and the third valve 4 are all ball valves.

[0020] A second pressure sensor 15 and a second temperature sensor 14 are also installed on the water inlet pipe.

[0021] The technical solution of this utility model is implemented as follows:

[0022] 1. Air source chiller / heater unit 13: Equipped with the ability to switch between cooling and heating modes within an outdoor temperature range of -12℃ to 40℃; cooling and heating capacity can reach 30KW. In order to control the outlet water temperature of the air source chiller / heater unit 13 to be relatively constant, a dual-frequency conversion DC scroll compressor is adopted, which can realize stepless adjustment of cooling and heating to ensure stable water supply temperature requirements.

[0023] 2. Circulating water pump 9: The variable frequency circulating water pump provides the circulating power for the test system. It is also equipped with a frequency converter. By changing the pump frequency, the thermal response test results at different flow velocities in the pipe can be studied. The flow rate and head of the variable frequency circulating water pump must meet the flow rate and head requirements of the 400-meter deep double U-shaped buried borehole.

[0024] 3. Flow Sensor 2: An electromagnetic flow meter with an LCD display can directly show real-time flow rate and velocity. It can also connect to a data acquisition unit for automatic recording of current signals. The electromagnetic flow meter has an accuracy of 0.5%.

[0025] 4. First temperature sensor 6 and second temperature sensor 14: The first temperature sensor is a PT100 platinum resistance thermometer with an accuracy of 0.2℃, used to monitor the inlet and outlet water temperature of the test hole (buried hole).

[0026] 5. First pressure sensor 5 and second pressure sensor 15: used to monitor the pressure change of the test hole under different flow rates.

[0027] 6. Electric heater 8: A 24KW electric heater is used, and the heating power and heating temperature can be automatically adjusted. It is used to supplement the insufficient heating capacity of the air source chiller unit 13. At the same time, it can be used alone for the heating condition test of the system, outputting stable heat or stable outlet water temperature to ensure the stability of the system and meet the summer condition test requirements of the tester.

[0028] 7. Buffer water tank 11: In order to study the physical parameters of soil under different working conditions, a water tank with adjustable power and energy storage function is required. At the same time, in order to avoid the unstable outlet water temperature of the air source chiller unit 13, a water tank with buffer function is added. Different heating powers can be combined according to actual test needs to achieve different energy inputs in summer working conditions. It works with the air source chiller unit 13 to adjust the input cooling capacity in winter working conditions to ensure stability under test conditions.

[0029] 8. First bypass valve 7 and second bypass valve 10: Adjust the flow rate into the air source chiller unit 13 to ensure that the water flow switch of the air source chiller unit 13 is opened normally and the unit is running normally under low flow test conditions.

[0030] Winter heating condition test: Fill the pipeline with water through the buffer water tank 11, turn on the circulating water pump 9, adjust the frequency of the circulating water pump 9, open the first bypass valve 7, close the second bypass valve 10, and close the second valve 3 and the third valve 4 entering the buried pipe heat exchanger 1 to ensure that the flow switch of the air source chiller unit 13 is open. Then turn on the air source chiller unit 13 into the cooling condition, set the outlet water temperature of the air source chiller unit 13 to meet the test condition requirements, and the outlet water of the air source chiller unit 13 first enters the buffer water tank 11 to cool the water temperature of the buffer water tank 11 to the test condition requirements. Then open the second valve 3 and the third valve 4, set the frequency of the circulating water pump 9 to make the water flow rate entering the buried pipe heat exchanger 1 in the test hole (buried hole) meet the flow rate requirements of the buried pipe under test, and start the winter condition test. During this period, the heat pump unit runs continuously and data is collected.

[0031] Summer cooling condition test: Fill the pipeline with water through the buffer water tank 11, turn on the circulating water pump 9, adjust the frequency of the circulating water pump 9, open the first bypass valve 7, close the second bypass valve 10, and close the second valve 3 and the third valve 4 to ensure that the flow switch of the air source chiller unit 13 is open. Then turn on the air source chiller unit 13 to the heating condition, set the outlet water temperature of the air source chiller unit 13 to meet the test condition requirements, and the outlet water of the air source chiller unit 13 first enters the buffer water tank 11 to heat the water temperature of the buffer water tank 11 to the test condition requirements. Then open the second valve 3 and set the frequency of the circulating water pump 9 so that the water flow rate entering the buried pipe heat exchanger 1 in the test hole (buried hole) meets the flow rate requirements of the buried pipe under test. The summer condition test begins, during which the heat pump unit runs continuously and data is recorded and collected.

[0032] The ground source heat pump buried pipe heat exchange capacity testing device described in this utility model can not only test the summer operating conditions of the buried ground source heat pump, but also meet the testing requirements for winter operating conditions. By using an electric heater with increased capacity and an air source heat pump unit, and selecting a variable frequency circulating water pump that meets the required flow rate and head for buried holes at depths of 400 meters and above, this utility model meets the heat exchange testing requirements of buried pipes at different depths, improves the accuracy of soil thermal property parameters in the test area, and provides stronger support for the design of buried pipe ground source heat pumps.

[0033] Furthermore, it should be understood that those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A device for testing the heat exchange capacity of a ground source heat pump buried pipe, characterized in that: The system includes a buried pipe heat exchanger (1), an air source chiller / hot water unit (13), an inlet pipe connected to the buried pipe heat exchanger (1), and an outlet pipe connected to the buried pipe heat exchanger (1). The inlet pipe is connected to the outlet of the air source chiller / hot water unit (13), and the outlet pipe is connected to the inlet of the air source chiller / hot water unit (13). The inlet pipe is equipped with a first valve (12), a buffer tank (11), a circulating water pump (9), an electric heater (8), a second valve (3), and a flow sensor (2) in sequence according to the flow direction of the water. One end of the first valve (12) is connected to the outlet of the air source chiller / hot water unit (13), and the other end of the first valve (12) is connected to the buffer tank (11). The input end of the circulating water pump (9) is connected to the buffer tank (11), and the output end of the circulating water pump (9) is connected to the buffer tank (11). The outlet is connected to one end of the electric heater (8), and the other end of the electric heater (8) is connected to the first end of the second valve (3); the outlet pipe is provided with a first pressure sensor (5), a first temperature sensor (6) and a third valve (4) in sequence according to the direction of water flow, and the first end of the third valve (4) is connected to the inlet end of the air source chiller (13); a first bypass valve (7) and a second bypass valve (10) are also provided between the outlet pipe and the inlet pipe, one end of the first bypass valve (7) is connected to the first end of the third valve (4), and the other end of the first bypass valve (7) is connected to the first end of the second valve (3); one end of the second bypass valve (10) is connected to the inlet end of the air source chiller (13), and the other end of the second bypass valve (10) is connected to the input end of the circulating water pump (9).

2. The ground source heat pump buried pipe heat exchange capacity testing device according to claim 1, characterized in that: The circulating water pump (9) is a variable frequency circulating water pump.

3. The ground source heat pump buried pipe heat exchange capacity testing device according to claim 1, characterized in that: The air source chiller / hot water unit (13) is driven and controlled by a DC inverter motor.

4. The ground source heat pump buried pipe heat exchange capacity testing device according to claim 1, characterized in that: The first valve (12), the second valve (3) and the third valve (4) are all ball valves.

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