Comprehensive Performance Test Device and Method for a Multi-Source Heat Complementary Transcritical Carbon Dioxide Heat Pump System

Abstract

An integrated performance test device and method for a multi-heat-source complementary transcritical carbon dioxide heat pump system, comprising a heat pump system, a multi-heat-source system and a data acquisition and control system; the heat pump system switches simple two-stage compression cycle circuits, two-stage compression flash tank intermediate gas injection cycle circuits, and two-stage compression heat exchanger intermediate gas injection cycle circuits by manually adjusting the valve switches; the multi-heat-source system includes an environmental simulation chamber and an evaporator, a solar energy simulation device, a fan and a waste heat recovery device in the environmental simulation chamber; the data acquisition and control system can automatically control the cooling water heating temperature, the exhaust pressure and the intermediate gas injection pressure according to the set values. The present invention can carry out the performance tests of simple two-stage compression cycle, two-stage compression flash tank intermediate gas injection cycle and two-stage compression regenerator intermediate gas injection cycle heat pumps in one test device, and simultaneously utilize various renewable energy sources such as air source, water source and solar energy. The structure is compact, the test range is more comprehensive, and the test cost and space are saved.

Description

Technical Field

[0001] The invention belongs to the technical field of transcritical carbon dioxide heat pumps, and particularly relates to a comprehensive performance test device and method for a transcritical carbon dioxide heat pump system with multi-source complementarity and switching of multiple circulation modes. Background Art

[0002] A heat pump is a renewable energy device that uses air, geothermal energy, solar energy, industrial waste heat, etc. as heat sources, is driven by electric energy, and converts low-grade heat energy into high-grade heat energy. Under normal circumstances, the heating capacity of a heat pump must be greater than the power consumption of the compressor, so it is more environmentally friendly and energy-saving than electric heating elements. Compared with traditional Freon refrigerants, carbon dioxide is an environmentally friendly natural working fluid (ODP = 0, GWP = 1), easy to obtain, non-flammable, non-toxic, has good heat transfer performance, high refrigeration capacity per unit volume, and low critical temperature. The transcritical carbon dioxide heat pump cycle gives full play to the advantages of carbon dioxide working fluid. Utilizing the temperature glide during the heat release process of carbon dioxide under supercritical conditions, the heating water temperature can reach above 90°C, while traditional heat pumps are generally above 60°C, and it can also operate under very low outdoor temperatures in winter, having good development and application prospects.

[0003] However, due to the too high pressure in the supercritical carbon dioxide cycle, problems such as shortened compressor life, increased power consumption, and decreased heating coefficient will occur. Therefore, in a transcritical carbon dioxide heat pump, a two-stage compression with intermediate gas injection method is often adopted to reduce the pressure ratio of each stage of the compressor, improve the compressor performance, and increase the system thermal efficiency. According to the gas injection method, it can be divided into a flash tank intermediate gas injection heat pump and a regenerator intermediate gas injection heat pump. In addition, solar energy is unstable due to geographical location and climate conditions; air source heat pumps have been widely used, but in cold weather, the heating demand increases while the heat pump efficiency decreases instead, unable to meet the heating demand; the waste heat of wastewater has a low energy grade and cannot generate high-temperature heating. Adopting a heat pump system with multi-source complementarity, comprehensively considering the performance characteristics of each heat source, is beneficial to improving the stability and safety of the heat pump system, increasing the heating efficiency, reducing the operating cost, conforming to the development trend of energy conservation and emission reduction, and is an important way to achieve high-quality heating in the future. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a comprehensive performance test device and method for a transcritical carbon dioxide heat pump that complements and comprehensively utilizes multiple renewable heat sources (solar energy, air energy, and wastewater waste heat); this device can switch among three cycles: a simple two-stage compression cycle circuit, a flash tank intermediate gas injection two-stage compression cycle circuit, and a regenerator intermediate gas injection two-stage compression cycle circuit. On this experimental device, various heat pump performance test experiments with different cycle modes can be carried out for a long time, and the experimental data can be collected, saving the space of the experimental device, reducing the experimental cost, and improving the experimental credibility.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A comprehensive performance test device for a multi-source complementary transcritical carbon dioxide heat pump system, comprising a first passage, a second passage, a third passage, a regenerator, a flash tank and a multi-source system;

[0007] Along the flow direction, the first passage is connected and composed of a low-pressure stage compressor, a high-pressure stage compressor, a gas cooler and a first mass flowmeter; the second passage is connected and composed of a first electronic expansion valve, an evaporator and a gas-liquid separator; the third passage is connected and composed of an electric heater and a second mass flowmeter; the end of the third passage is connected to the outlet of the low-pressure stage compressor, and the end of the second passage is connected to the start of the first passage;

[0008] The multi-source system includes an environmental simulation chamber, and the evaporator is arranged in the environmental simulation chamber;

[0009] Connecting the end of the first passage to the start of the second passage, the first passage and the second passage form a simple two-stage compression heat pump cycle loop;

[0010] Dividing the end of the first passage into two a branches, the first a branch is connected to the start of the third passage through a second electronic expansion valve and the low-pressure side of the regenerator, and the second a branch is connected to the start of the second passage through the high-pressure side of the regenerator, then the first passage, the second passage, the third passage and the two a branches form a two-stage compression regenerator intermediate gas injection heat pump cycle loop;

[0011] Connecting the end of the first passage to a second electronic expansion valve and a flash tank in sequence, the outlet of the flash tank is divided into two b branches, the first b branch is connected to the start of the third passage through a third electronic expansion valve, and the second b branch is connected to the start of the second passage, then the first passage, the second passage, the third passage and the two b branches form a two-stage compression flash tank intermediate gas injection heat pump cycle loop.

[0012] In one embodiment, a first manual regulating valve is provided at the inlet of the flash tank, a fifth manual regulating valve is provided on the second b branch, a second manual regulating valve is provided at the inlet of the low-pressure side of the regenerator, a sixth manual regulating valve is provided at the outlet, a third manual regulating valve is provided at the inlet of the high-pressure side, and a fourth manual regulating valve is provided at the outlet;

[0013] Close the first manual regulating valve, the second manual regulating valve, the fifth manual regulating valve, and the sixth manual regulating valve, open the third manual regulating valve and the fourth manual regulating valve, and switch to a simple two-stage compression cycle; close the second manual regulating valve, the sixth manual regulating valve, the third manual regulating valve, and the fourth manual regulating valve, open the first manual regulating valve and the fifth manual regulating valve, and switch to a two-stage compression flash tank gas replenishment cycle; close the first manual regulating valve and the fifth manual regulating valve, open the third manual regulating valve, the fourth manual regulating valve, the second manual regulating valve, and the sixth manual regulating valve, and switch to a two-stage compression regenerator gas replenishment cycle.

[0014] In one embodiment, the evaporator heat sources include three types: a fan, a waste heat recovery device for wastewater, and a solar simulation device. The fan provides heat energy in the air through a finned tube heat exchanger to heat the refrigerant. In the waste heat recovery device for wastewater, the wastewater flows through a shell-and-tube heat exchanger to exchange heat with the refrigerant. In the solar simulation device, the solar simulator heats the heat transfer fluid in the heat collecting tube, and the heat transfer fluid exchanges heat with the refrigerant. The evaporators of the three heat source types are arranged in series, and the refrigerant is heated in sequence according to the different grades of the heat sources from low to high.

[0015] In one embodiment, the first passage further includes a first heat exchanger and a second heat exchanger. The first heat exchanger is connected between the high-pressure stage compressor and the gas cooler, and the second heat exchanger is connected between the gas cooler and the first mass flowmeter. The first heat exchanger and the second heat exchanger are shell-and-tube heat exchangers, and their functions are to adjust the heat exchange area of the gas cooler.

[0016] In one embodiment, the gas cooler is connected to a chiller. The chiller provides constant temperature cooling water for the gas cooler. A third mass flowmeter is provided on the connecting pipeline, and a first differential pressure transmitter is provided between the inlet and outlet of the gas cooler; a second differential pressure transmitter is provided between the inlet and outlet of the low-pressure side of the regenerator, and a third differential pressure transmitter is provided between the inlet and outlet of the high-pressure side; a fourth differential pressure transmitter is provided between the inlet and outlet of the evaporator.

[0017] In one embodiment, the two-stage compression method is used to reduce the pressure ratio and improve the efficiency of a single compressor. In addition, the two-stage compression can also achieve the function of inter-stage gas replenishment. The low-pressure refrigerant from the outlet of the evaporator first enters the low-pressure stage compressor and is compressed to an intermediate pressure state, and then enters the high-pressure stage compressor and is continuously compressed to a high pressure state. Both the low-pressure stage compressor and the high-pressure stage compressor are rotary variable-frequency compressors.

[0018] In one embodiment, a temperature sensor is installed at the outlet of the cooling water of the gas cooler, and pressure sensors are installed at the outlets of the high-pressure stage compressor and the electric heater to respectively measure the exhaust pressure and the intermediate gas replenishing pressure. The temperature sensor, the pressure sensors and each differential pressure transmitter are all connected to the data acquisition and control system.

[0019] The present invention also provides a test method using the comprehensive performance test device of the multi-source complementary transcritical carbon dioxide heat pump system, including:

[0020] 1) Simple two-stage compression cycle system test:

[0021] Connect the simple two-stage compression heat pump cycle loop, close other loops, and let the refrigerant directly enter the evaporator after passing through the gas cooler to conduct the simple two-stage compression cycle system test;

[0022] 2) Two-stage compression flash tank gas replenishing cycle system test:

[0023] Connect the intermediate gas replenishing heat pump cycle loop of the two-stage compression regenerator, close other loops, and let the refrigerant flash in the flash tank after passing through the gas cooler to conduct the two-stage compression flash tank gas replenishing cycle system test;

[0024] 3) Two-stage compression regenerator gas replenishing cycle system test:

[0025] Connect the intermediate gas replenishing heat pump cycle loop of the two-stage compression flash tank, close other loops, and let the refrigerant exchange heat in the regenerator after passing through the gas cooler to conduct the two-stage compression regenerator gas replenishing cycle system test.

[0026] In one embodiment, using the data acquisition and control system, the heating temperature of the cooling water after exchanging heat with the refrigerant is obtained through the temperature sensor, and the rotational speeds of the high-pressure stage compressor and the low-pressure stage compressor are controlled according to the heating temperature of the cooling water. If the temperature is lower than the set value, increase the rotational speeds of the high-pressure stage compressor and the low-pressure stage compressor; otherwise, decrease the rotational speeds of the high-pressure stage compressor and the low-pressure stage compressor until the temperature of the cooling water after heating is the same as the set value, and the rotational speeds of the high-pressure stage compressor and the low-pressure stage compressor are kept consistent;

[0027] Using the data acquisition and control system, the exhaust pressure of the compressor is obtained through the pressure sensor, and the opening degree of the first electronic expansion valve is adjusted to control the exhaust pressure. If the exhaust pressure is greater than the set value, increase the opening degree of the first electronic expansion valve; otherwise, decrease the opening degree of the first electronic expansion valve until the exhaust pressure is the same as the set value;

[0028] Utilize the data acquisition control system to obtain the intermediate air supply pressure of the compressor through the pressure sensor, and adjust the opening of the second electronic expansion valve to control the intermediate air supply pressure. If the intermediate air supply pressure is greater than the set value, reduce the opening of the second electronic expansion valve, otherwise increase the opening of the second electronic expansion valve until the intermediate air supply pressure is the same as the set value.

[0029] In one embodiment, in the environmental simulation chamber, evaporators of three different types of heat sources, namely, a fan, a wastewater heat recovery device and a solar energy simulation device, are arranged in series, and the refrigerant is heated by using heat sources of different qualities, and the heat source device switch is turned on or off to combine multiple heat source utilization methods.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. In a comprehensive performance test device for a multi-heat source complementary transcritical carbon dioxide heat pump system provided by the present invention, through the cooperation of a manual regulating valve switch, three modes of a simple two-stage compression circulation loop, a flash tank intermediate air supply circulation loop, and a regenerator intermediate air supply circulation loop can be switched on a test bench, which is convenient for carrying out comparative experiments, making the experimental test more comprehensive, greatly saving the test bench space and cost, and increasing the reliability of the comparative experimental results;

[0032] 2. In the comprehensive performance test device of a multi-heat source complementary transcritical carbon dioxide heat pump system provided by the present invention, the heat sources include three types of renewable energy sources, namely solar energy, air energy and waste water waste heat. Different energy sources complement each other, and the experimental research on multi-heat source complementary heat pumps is carried out, which meets the policy requirements of optimizing the energy structure, reducing greenhouse gas emissions, and achieving energy conservation and emission reduction;

[0033] 3. In a comprehensive performance testing device for a multi-heat source complementary transcritical carbon dioxide heat pump system provided by the present invention, the shell-and-tube heat exchangers arranged at both ends of the gas cooler and the evaporator are mainly used to change the heat exchange area of ​​the gas cooler and the evaporator, thereby carrying out component-level experiments and expanding the scope of the experiments.

[0034] 4. In a comprehensive performance testing device for a multi-heat source complementary transcritical carbon dioxide heat pump system provided by the present invention, temperature, pressure sensors and flow meters are connected to a data acquisition and control system to realize the recording of real-time changes in non-steady-state operating data, making the test more comprehensive.

[0035] 5. In a comprehensive performance testing device for a multi-heat source complementary transcritical carbon dioxide heat pump system provided by the present invention, the compressor speed and the opening of the electronic expansion valve are automatically adjusted so that the cooling water outlet temperature, exhaust pressure and intermediate air supply pressure reach the set values, thereby realizing automatic control.

[0036] 6. In the comprehensive performance test device of a multi-heat-source complementary transcritical carbon dioxide heat pump system provided by the present invention, the refrigerant uses natural working medium carbon dioxide, which is pollution-free to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic structural diagram of the present invention.

[0038] Figure 2 It is a schematic diagram of the present invention switched to a simple two-stage compression cycle.

[0039] Figure 3 It is a schematic diagram of the present invention switched to an intermediate gas injection cycle of a two-stage compression flash tank.

[0040] Figure 4 It is a schematic diagram of the present invention switched to an intermediate gas injection cycle of a two-stage compression recuperator.

[0041] In the drawings: 1. low-pressure stage compressor; 2. high-pressure stage compressor; 3. first heat exchanger; 4. chiller; 5. third mass flowmeter; 6. first differential pressure transmitter; 7. gas cooler; 8. second heat exchanger; 9. first mass flowmeter; 10. second electronic expansion valve; 11. first manual regulating valve; 12. second manual regulating valve; 13. third manual regulating valve; 14. second differential pressure transmitter; 15. third differential pressure transmitter; 16. recuperator; 17. fourth manual regulating valve; 18. fifth manual regulating valve; 19. sixth manual regulating valve; 20. first electronic expansion valve; 21. environmental simulation chamber; 22. gas-liquid separator; 23. fourth differential pressure transmitter; 24. evaporator; 25. solar energy simulation device; 26. waste heat recovery device; 27. fan; 28. flash tank; 29. third electronic expansion valve; 30. electric heater; 31. second mass flowmeter; 32. data acquisition and control system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following will describe in detail the embodiments of the present invention with reference to the drawings and embodiments.

[0043] A comprehensive performance test device of a multi-heat-source complementary transcritical carbon dioxide heat pump system according to the present invention, functionally, its components include a heat pump system and a multi-heat-source system, and may further include a data acquisition and control system. Refer to Figure 1 , structurally, its components include a first passage, a second passage, a third passage, a recuperator 16, a flash tank 28 and a multi-heat-source system, and may further include a data acquisition and control system.

[0044] Along the flow direction, the first passageway is composed of a low-pressure stage compressor 1, a high-pressure stage compressor 2, a gas cooler 7, and a first mass flowmeter 9 connected. The second passageway is composed of a first electronic expansion valve 20, an evaporator 24, and a gas-liquid separator 22 connected. The third passageway is composed of an electric heater 30 and a second mass flowmeter 31 connected. The end of the third passageway is connected to the outlet of the low-pressure stage compressor 1, and the end of the second passageway is connected to the start of the first passageway.

[0045] The multi-heat source system includes an environmental simulation chamber 21, and the evaporator 24 is arranged in the environmental simulation chamber 21.

[0046] The heat pump system of the present invention can switch between a simple two-stage compression cycle circuit, a two-stage compression flash tank intermediate gas injection cycle circuit, and a two-stage compression heat exchanger intermediate gas injection cycle circuit. Specifically:

[0047] Connect the end of the first passageway to the start of the second passageway, then the first passageway and the second passageway form a simple two-stage compression heat pump cycle circuit.

[0048] Divide the end of the first passageway into two a branches. The first a branch is connected to the start of the third passageway through the second electronic expansion valve 10 and the low-pressure side of the regenerator 16, and the second a branch is connected to the start of the second passageway through the high-pressure side of the regenerator 16. Then the first passageway, the second passageway, the third passageway, and the two a branches form a two-stage compression regenerator intermediate gas injection heat pump cycle circuit.

[0049] Connect the end of the first passageway to the second electronic expansion valve 10 and the flash tank 28 in sequence. The outlet of the flash tank 28 is divided into two b branches. The first b branch is connected to the start of the third passageway through the third electronic expansion valve 29, and the second b branch is connected to the start of the second passageway. Then the first passageway, the second passageway, the third passageway, and the two b branches form a two-stage compression flash tank intermediate gas injection heat pump cycle circuit.

[0050] Exemplarily, the above switching can be achieved by reasonably setting valves, that is, the above switching can be achieved by manually or automatically adjusting the valve switches. Specifically: a first manual regulating valve 11 is arranged at the inlet of the flash tank 28, a fifth manual regulating valve 18 is arranged on the second b branch, a second manual regulating valve 12 is arranged at the inlet of the low-pressure side of the regenerator 16, a sixth manual regulating valve 19 is arranged at the outlet, a third manual regulating valve 13 is arranged at the inlet of the high-pressure side, and a fourth manual regulating valve 17 is arranged at the outlet. The specific switching means will be described in combination with the appendix in the test method. Figure 2 It will be described.

[0051] Exemplarily, in the present invention, there are three heat sources for the evaporator 24, that is, the multiple heat sources in the present invention are specifically three renewable energy sources, namely the fan 27, the waste heat recovery device 26 for wastewater, and the solar simulation device 25. The fan 27 provides the heat energy in the air through a finned-tube heat exchanger to heat the refrigerant. In the waste heat recovery device 26 for wastewater, the wastewater flows through a shell-and-tube heat exchanger to exchange heat with the refrigerant. In the solar simulation device 25, the solar simulator heats the heat transfer fluid in the heat collecting tube, and the heat transfer fluid exchanges heat with the refrigerant. The evaporators of the three heat source types can be arranged in series. By utilizing the different grades of the heat sources, the refrigerant can be heated successively from low to high. Moreover, by turning on or off the switches of different heat source devices, various combinations of heat source utilization methods can be achieved.

[0052] By adopting this heating method, it is possible to complement each other among different energy sources, and then conduct experimental research on a multi-source complementary heat pump. Obviously, when one or two heat sources are turned off, single-source experimental research can be carried out.

[0053] According to the above structure, the present invention can conduct heat pump performance tests on simple two-stage compression cycles, two-stage compression flash tank intermediate gas injection cycles, and two-stage compression regenerator intermediate gas injection cycles in a single test device. At the same time, it can utilize various renewable energy sources such as air source, water source, and solar energy. The structure is compact, the test range is more comprehensive, and the test cost and space are saved.

[0054] In a further embodiment of the present invention, the first passage further includes a first heat exchanger 3 and a second heat exchanger 8. The first heat exchanger 3 is connected between the high-pressure stage compressor 2 and the gas cooler 7, and the second heat exchanger 8 is connected between the gas cooler 7 and the first mass flowmeter 9. The first heat exchanger 3 and the second heat exchanger 8 are shell-and-tube heat exchangers, and their functions are to adjust the heat exchange area of the gas cooler.

[0055] In a further embodiment of the present invention, the gas cooler 7 is a heat dissipation component. In the gas cooler 7, the refrigerant vapor exchanges heat with the cooling water to generate the required hot water. The gas cooler 7 is connected to a chiller 4. The chiller 4 provides constant-temperature cooling water for the gas cooler 7. A third mass flowmeter 5 is provided on the connecting pipeline. Moreover, a first differential pressure transmitter 6 is provided between the inlet and outlet of the gas cooler 7, a second differential pressure transmitter 14 is provided between the inlet and outlet of the low-pressure side of the regenerator 16, a third differential pressure transmitter 15 is provided between the inlet and outlet of the high-pressure side, and a fourth differential pressure transmitter 23 is provided between the inlet and outlet of the evaporator 24.

[0056] In a further embodiment of the present invention, a two-stage compression method is used to reduce the pressure ratio and improve the efficiency of a single compressor. In addition, the two-stage compression can also achieve the function of inter-stage gas replenishment. The low-pressure refrigerant at the outlet of the evaporator first enters a compressor and is compressed to an intermediate pressure state. The compressor is the low-pressure stage compressor 1. Then it enters the second compressor and is continuously compressed to a high-pressure state. The compressor is the high-pressure stage compressor 2. Both the low-pressure stage compressor 1 and the high-pressure stage compressor 2 are rotary variable-frequency compressors.

[0057] In a further embodiment of the present invention, a temperature sensor is installed at the cooling water outlet of the gas cooler 7, a pressure sensor is installed at the outlet of the high-pressure stage compressor 2, and a pressure sensor is installed at the outlet of the electric heater 30. The temperature sensor and the pressure sensor are connected to the data acquisition and control system 32. The data acquisition and control system 32 can automatically control the cooling water heating temperature, the exhaust pressure, and the intermediate gas replenishment pressure according to the set values.

[0058] The test method of the present invention is as follows:

[0059] 1) Simple two-stage compression cycle system test:

[0060] See Figure 2 , close the first manual regulating valve 11, the second manual regulating valve 12, the fifth manual regulating valve 18, and the sixth manual regulating valve 19, and open the third manual regulating valve 13 and the fourth manual regulating valve 17, so that the refrigerant directly enters the evaporator 24 after passing through the gas cooler 7, and perform a simple two-stage compression cycle system test.

[0061] 2) Two-stage compression flash tank gas replenishment cycle system test:

[0062] See Figure 3 , close the second manual regulating valve 12, the sixth manual regulating valve 19, the third manual regulating valve 13, and the fourth manual regulating valve 17, and open the first manual regulating valve 11 and the fifth manual regulating valve 18, so that the refrigerant flashes in the flash tank 28 after passing through the gas cooler 7, and perform a two-stage compression flash tank gas replenishment cycle system test.

[0063] 3) Two-stage compression regenerator gas replenishment cycle system test:

[0064] See Figure 4 , close the first manual regulating valve 11 and the fifth manual regulating valve 18, and open the third manual regulating valve 13, the fourth manual regulating valve 17, the second manual regulating valve 12, and the sixth manual regulating valve 19, so that the refrigerant exchanges heat in the regenerator 16 after passing through the gas cooler 7, and perform a two-stage compression regenerator gas replenishment cycle system test.

[0065] In a further embodiment of the present invention, a temperature sensor is installed at the cooling water outlet of the gas cooler 7. The data acquisition and control system 32 obtains the heating temperature of the cooling water after heat exchange with the refrigerant through the temperature sensor, and controls the rotational speeds of the two compressors according to the heating temperature of the cooling water. If the temperature is lower than the set value, the rotational speed of the compressor is increased; otherwise, it is decreased until the temperature of the cooling water after heating is the same as the set value and remains stable, and the rotational speeds of the high-pressure stage compressor 2 and the low-pressure stage compressor 1 are kept consistent.

[0066] In a further embodiment of the present invention, a pressure sensor is installed at the outlet of the high-pressure stage compressor 2 to measure the exhaust pressure. The data acquisition and control system 32 obtains the exhaust pressure of the compressor through the pressure sensor, and adjusts the opening degree of the first electronic expansion valve 20 to control the exhaust pressure. If the exhaust pressure is greater than the set value, the opening degree of the first electronic expansion valve 20 is increased; otherwise, it is decreased until the exhaust pressure is the same as the set value and remains stable.

[0067] In a further embodiment of the present invention, a pressure sensor is installed at the outlet of the electric heater 30 to measure the intermediate gas replenishing pressure. The data acquisition and control system 32 obtains the intermediate gas replenishing pressure of the compressor through the temperature sensor, and adjusts the opening degree of the second electronic expansion valve 10 to control the intermediate gas replenishing pressure. If the intermediate gas replenishing pressure is greater than the set value, the opening degree of the second electronic expansion valve 10 is decreased; otherwise, it is increased until the intermediate gas replenishing pressure is the same as the set value and remains stable.

[0068] Before the experiment starts, turn on the heat source combination required for the test, manually adjust the valve, select the type of heat pump cycle to be tested, open the third electronic expansion valve 29 to the maximum opening degree, and adjust the opening degrees of the first electronic expansion valve 20 and the second electronic expansion valve 10 to the intermediate values.

[0069] During the experiment, first start the high-pressure stage compressor 2, and then start the low-pressure stage compressor 1. When the system pressure rises and reaches a stable value, start the automatic control function of the data acquisition and control system 32.

[0070] By testing different heat pump cycle modes and different heat source combinations, the influence of different cycle modes on the performance of the transcritical carbon dioxide heat pump system and the influence of different multi-heat-source complementary modes on the performance of the transcritical carbon dioxide heat pump system can be evaluated. For example:

[0071] 1) In order to study the influence of the transcritical carbon dioxide air-source heat pump cycle mode on the system performance under low-temperature conditions, the waste heat recovery device 26 and the solar energy simulation device 25 are turned off, the fan 27 is turned on, the ambient temperature is set to -10°C, and the simple two-stage compression cycle system test, the two-stage compression flash tank gas-injection cycle system test, and the two-stage compression recuperator gas-injection cycle system test are respectively carried out. The heating performances under the three cycle modes are compared to find the advantages and disadvantages of different cycles.

[0072] 2) In order to study the complementary utilization mode of three heat sources, namely air source, waste heat of wastewater, and solar energy, under low-temperature conditions, the second manual regulating valve 12, the sixth manual regulating valve 19, the third manual regulating valve 13, and the fourth manual regulating valve 17 are closed, the first manual regulating valve 11 and the fifth manual regulating valve 18 are opened, the cycle is switched to the two-stage compression flash tank gas-injection transcritical carbon dioxide heat pump cycle, the ambient temperature is set to 0°C, the wastewater temperature is set to 10°C, and the solar simulator temperature is set to 50°C to explore the optimal scheme of the heat output ratio of the three heat sources under this working condition.

Claims

1. An integrated performance test device for a multi-heat-source complementary transcritical carbon dioxide heat pump system, characterized in that, It includes a first passage, a second passage, a third passage, a regenerator (16), a flash tank (28) and a multi-heat-source system; Along the flow direction, the first passage is composed of a low-pressure stage compressor (1), a high-pressure stage compressor (2), a gas cooler (7), and a first mass flowmeter (9) connected; the second passage is composed of a first electronic expansion valve (20), an evaporator (24), and a gas-liquid separator (22) connected; the third passage is composed of an electric heater (30) and a second mass flowmeter (31) connected; the end of the third passage is connected to the outlet of the low-pressure stage compressor (1), and the end of the second passage is connected to the start of the first passage; The multi-heat-source system includes an environmental simulation chamber (21), and the evaporator (24) is arranged in the environmental simulation chamber (21); Connecting the end of the first passage to the start of the second passage, the first passage and the second passage form a simple two-stage compression heat pump cycle loop; Dividing the end of the first passage into two a branches, the first a branch is connected to the start of the third passage through the low-pressure side of the second electronic expansion valve (10) and the regenerator (16), and the second a branch is connected to the start of the second passage through the high-pressure side of the regenerator (16), then the first passage, the second passage, the third passage and the two a branches form a two-stage compression regenerator intermediate gas injection heat pump cycle loop; Connecting the end of the first passage to the second electronic expansion valve (10) and the flash tank (28) in sequence, the outlet of the flash tank (28) is divided into two b branches, the first b branch is connected to the start of the third passage through the third electronic expansion valve (29), and the second b branch is connected to the start of the second passage, then the first passage, the second passage, the third passage and the two b branches form a two-stage compression flash tank intermediate gas injection heat pump cycle loop.

2. The comprehensive performance test device for the multi-heat-source complementary transcritical carbon dioxide heat pump system according to claim 1, characterized in that, A first manual regulating valve (11) is arranged at the inlet of the flash tank (28), a fifth manual regulating valve (18) is arranged on the second b branch, a second manual regulating valve (12) is arranged at the inlet of the low-pressure side of the regenerator (16), a sixth manual regulating valve (19) is arranged at the outlet, a third manual regulating valve (13) is arranged at the inlet of the high-pressure side, and a fourth manual regulating valve (17) is arranged at the outlet; Closing the first manual regulating valve (11), the second manual regulating valve (12), the fifth manual regulating valve (18), the sixth manual regulating valve (19), and opening the third manual regulating valve (13), the fourth manual regulating valve (17) to switch to a simple two-stage compression cycle; closing the second manual regulating valve (12), the sixth manual regulating valve (19), the third manual regulating valve (13), the fourth manual regulating valve (17), and opening the first manual regulating valve (11), the fifth manual regulating valve (18) to switch to a two-stage compression flash tank gas injection cycle; closing the first manual regulating valve (11), the fifth manual regulating valve (18), and opening the third manual regulating valve (13), the fourth manual regulating valve (17), the second manual regulating valve (12), the sixth manual regulating valve (19) to switch to a two-stage compression regenerator gas injection cycle.

3. The comprehensive performance test device for a multi-heat-source complementary transcritical carbon dioxide heat pump system according to claim 1, wherein The heat sources of the evaporator (24) include three types: a fan (27), a waste water waste heat recovery device (26) and a solar energy simulation device (25). The fan (27) provides heat energy in the air through a fin-tube heat exchanger to heat the refrigerant. In the waste water waste heat recovery device (26), the waste water flows through a shell-and-tube heat exchanger to exchange heat with the refrigerant. In the solar energy simulation device (25), the solar energy simulator heats the heat transfer fluid in the heat collecting tube, and the heat transfer fluid exchanges heat with the refrigerant. The three types of heat source evaporators are arranged in series, and the refrigerant is heated in sequence from low to high by utilizing the different qualities of the heat sources.

4. The comprehensive performance test device for the multi-heat-source complementary transcritical carbon dioxide heat pump system according to claim 1, characterized in that, The first path also includes a first heat exchanger (3) and a second heat exchanger (8), wherein the first heat exchanger (3) is connected between the high-pressure compressor (2) and the gas cooler (7), and the second heat exchanger (8) is connected between the gas cooler (7) and the first mass flow meter (9), and the first heat exchanger (3) and the second heat exchanger (8) are shell-and-tube heat exchangers.

5. The comprehensive performance test device for the multi-heat-source complementary transcritical carbon dioxide heat pump system according to claim 4, wherein The low-pressure refrigerant from the evaporator outlet first enters the low-pressure stage compressor (1) to be compressed to an intermediate pressure state, and then enters the high-pressure stage compressor (2) to be continuously compressed to a high-pressure state. The low-pressure stage compressor (1) and the high-pressure stage compressor (2) are both rotary variable frequency compressors.

6. The comprehensive performance test device for the multi-heat-source complementary transcritical carbon dioxide heat pump system according to claim 4, characterized in that The gas cooler (7) is connected to a water chiller (4), and the water chiller (4) provides constant temperature cooling water for the gas cooler (7). A third mass flow meter (5) is arranged on the connecting pipeline, and a first differential pressure transmitter (6) is arranged between the inlet and outlet of the gas cooler (7); a second differential pressure transmitter (14) is arranged between the inlet and outlet on the low-pressure side of the regenerator (16), and a third differential pressure transmitter (15) is arranged between the inlet and outlet on the high-pressure side; and a fourth differential pressure transmitter (23) is arranged between the inlet and outlet of the evaporator (24).

7. The comprehensive performance test device for the multi-heat-source complementary transcritical carbon dioxide heat pump system according to claim 6, characterized in that, A temperature sensor is installed at the cooling water outlet of the gas cooler (7), and pressure sensors are installed at the outlet of the high-pressure compressor (2) and the outlet of the electric heater (30) to test the exhaust pressure and the intermediate air supply pressure respectively. The temperature sensor, the pressure sensor and each differential pressure transmitter are connected to the data acquisition control system (32).

8. A test method for the comprehensive performance test device of the multi-heat-source complementary transcritical carbon dioxide heat pump system according to any one of claims 1-7, characterized in that, include: 1) Simple two-stage compression cycle system test: The simple two-stage compression heat pump circulation loop is connected, and other loops are closed, so that the refrigerant directly enters the evaporator (24) after passing through the gas cooler (7), and the simple two-stage compression circulation system is tested; 2) Two-stage compression flash tank air supply circulation system test: The intermediate air supply heat pump circulation loop of the two-stage compression regenerator is connected, and other loops are closed, so that the refrigerant passes through the gas cooler (7) and then enters the flash tank (28) for flash evaporation, and the two-stage compression flash tank air supply circulation system is tested; 3) Two-stage compression regenerator air supply circulation system test: The intermediate air supply heat pump circulation loop of the two-stage compression flash tank is connected, and other loops are closed, so that the refrigerant passes through the gas cooler (7) and then exchanges heat in the regenerator (16), and the two-stage compression regenerator air supply circulation system is tested.

9. The test method according to claim 8, wherein Using the data acquisition control system (32), the heating temperature of the cooling water after heat exchange with the refrigerant is obtained through the temperature sensor, and the rotational speeds of the high-stage compressor (2) and the low-stage compressor (1) are controlled according to the heating temperature of the cooling water. If the temperature is lower than the set value, the rotational speeds of the high-stage compressor (2) and the low-stage compressor (1) are increased; otherwise, the rotational speeds of the high-stage compressor (2) and the low-stage compressor (1) are decreased until the temperature of the cooling water after heating is the same as the set value, and the rotational speeds of the high-stage compressor (2) and the low-stage compressor (1) are kept consistent. Using the data acquisition control system (32), the exhaust pressure of the compressor is obtained through the pressure sensor, and the opening degree of the first electronic expansion valve (20) is adjusted to control the exhaust pressure. If the exhaust pressure is greater than the set value, the opening degree of the first electronic expansion valve (20) is increased; otherwise, the opening degree of the first electronic expansion valve (20) is decreased until the exhaust pressure is the same as the set value. Using the data acquisition control system (32), the intermediate gas replenishing pressure of the compressor is obtained through the pressure sensor, and the opening degree of the second electronic expansion valve (10) is adjusted to control the intermediate gas replenishing pressure. If the intermediate gas replenishing pressure is greater than the set value, the opening degree of the second electronic expansion valve (10) is decreased; otherwise, the opening degree of the second electronic expansion valve (10) is increased until the intermediate gas replenishing pressure is the same as the set value.

10. The test method according to claim 9, characterized in that, In the environmental simulation chamber (21), the evaporators of three different heat source types, namely the fan (27), the waste heat recovery device (26) and the solar simulation device (25), are arranged in series to heat the refrigerant using different grades of heat sources, and the heat source device switches are turned on or off to combine various heat source utilization methods.

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