A variable frequency heat pump unit automatic control teaching experiment device and performance experiment method

Abstract

The present invention provides a variable frequency heat pump unit automatic control teaching experiment device and performance experiment method, the compressor inverter is electrically connected to the motor of the variable frequency compressor; the variable frequency compressor outlet is connected to the first interface of the four-way valve, the second interface of the four-way valve is connected to the first interface of the condenser, the second interface of the condenser is connected to the first interface of the regenerator, the second interface of the regenerator is connected to the inlet of the electronic expansion valve, the outlet of the electronic expansion valve is connected to the first interface of the evaporator, the second interface of the evaporator is connected to the third interface of the four-way valve, the fourth interface of the four-way valve is connected to the third interface of the regenerator, the fourth interface of the regenerator is connected to the inlet of the gas-liquid separator, and the outlet of the gas-liquid separator is connected to the inlet of the variable frequency compressor. The variable frequency heat pump unit automatic control teaching experiment device and performance experiment method provided by the present invention can realize refrigeration and heating functions, and is convenient for students to quantitatively analyze the performance influencing factors of refrigeration units and heat pump units.

Description

Technical Field

[0001] The invention belongs to the technical field of teaching experiment equipment, and in particular relates to a variable frequency heat pump unit automatic control teaching experiment device and a performance experiment method. Background Art

[0002] Most of the existing technologies are experimental teaching devices for the variable operating performance of refrigeration systems, and the control strategy and control algorithm of the test bench are not readable or writable. The experimental device manually adjusts the amount of chilled water. After the students observe that the liquid level meter is stable, they read the readings of the thermal measuring instruments installed on the chilled water pipeline system (including the inlet and outlet temperatures and the flow meter on the inlet pipe), and use the relevant calculation formulas to manually calculate the performance coefficient of the refrigeration system. The main components of the device include a compressor, a condenser, a thermal expansion valve, an evaporator, a chilled water inlet pipe, an outlet pipe, a gate valve, a thermometer and a flow meter. However, there are the following defects:

[0003] Defect 1: When the current teaching requires the realization of cooling and heating functions, the factors affecting the performance changes of the refrigeration unit and the heat pump unit should be quantitatively analyzed respectively, but the current experimental device can only realize the evaluation of the performance of a single refrigeration system;

[0004] Defect 2: It cannot realize the status monitoring of equipment performance under multiple working conditions and variable working conditions, and students cannot obtain real-time and historical data under variable working conditions;

[0005] Defect three: the valves used in the current experimental system are manual regulating valves, and the measuring instruments are traditional thermal measuring instruments. The experimental process is easily affected by students' operations, and the experimental data has large errors;

[0006] Defect 4: The current experimental device only controls the compressor to start and stop, and fails to achieve intelligent control. In current engineering practice projects, the control of heat pump units (chillers) on the market is a black box, that is, the control logic is pre-written and independently formed into modules. Students cannot fully understand its hardware composition and control logic relationship, cannot understand the coupling relationship between components, and cannot intuitively fully understand and grasp the changing relationship between various parameters when the working conditions change, so they cannot propose scientific and reasonable technical measures to reduce the energy consumption of equipment. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a variable frequency heat pump unit automatic control teaching experiment device and a performance experiment method, which can realize refrigeration and heating functions and facilitate students to quantitatively analyze the factors affecting the performance changes of refrigeration units and heat pump units.

[0008] To solve the above technical problems, the embodiments of the present invention adopt the following technical solutions:

[0009] In the first aspect, an embodiment of the present invention provides a variable frequency heat pump unit automatic control teaching experiment device, including a variable frequency compressor, a compressor inverter, a four-way valve, a condenser, a regenerator, an electronic expansion valve, an evaporator and a gas-liquid separator, wherein the compressor inverter is electrically connected to the motor of the variable frequency compressor; the outlet of the variable frequency compressor is connected to the first interface of the four-way valve, the second interface of the four-way valve is connected to the first interface of the condenser, the second interface of the condenser is connected to the first interface of the regenerator through a first pipeline, a second pipeline and a third pipeline that are connected in sequence, and the second interface of the regenerator is connected to the inlet of the electronic expansion valve The electronic expansion valve outlet is connected to the first interface of the evaporator through the fourth pipeline, the fifth pipeline and the sixth pipeline which are connected in sequence, the second interface of the evaporator is connected to the third interface of the four-way valve, the fourth interface of the four-way valve is connected to the third interface of the regenerator, the fourth interface of the regenerator is connected to the inlet of the gas-liquid separator, and the outlet of the gas-liquid separator is connected to the inlet of the variable frequency compressor; the connecting port of the first pipeline and the second pipeline is connected to the connecting port of the fourth pipeline and the fifth pipeline through the seventh pipeline; the connecting port of the second pipeline and the third pipeline is connected to the connecting port of the fifth pipeline and the sixth pipeline through the eighth pipeline;

[0010] Among them, the first interface and the second interface of the condenser are internally connected; the first interface and the second interface of the regenerator are internally connected, and the third interface and the fourth interface of the regenerator are internally connected; the first interface and the second interface of the evaporator are internally connected; a first one-way valve is provided on the second pipeline, and the flow direction of the first one-way valve is from the connecting port of the second pipeline and the first pipeline to the connecting port of the second pipeline and the third pipeline; a second one-way valve is provided on the seventh pipeline, and the flow direction of the second one-way valve is from the connecting port of the seventh pipeline and the fourth pipeline to the connecting port of the seventh pipeline and the second pipeline; a third one-way valve and a fourth ball valve are provided on the fifth pipeline, and the flow direction of the third one-way valve is from the connecting port of the fifth pipeline and the fourth pipeline to the connecting port of the fifth pipeline and the sixth pipeline; a third ball valve is provided on the eighth pipeline.

[0011] As a further improvement of the embodiment of the present invention, a pressure sensor and a temperature sensor are provided at the inlet and outlet of the variable frequency compressor.

[0012] As a further improvement of the embodiment of the present invention, temperature sensors and pressure sensors are provided at the four interfaces of the regenerator.

[0013] As a further improvement of the embodiment of the present invention, a pressure sensor and a temperature sensor are provided at the outlet of the electronic expansion valve.

[0014] As a further improvement of the embodiment of the present invention, an accumulator and a first ball valve are provided on the third pipeline, and in the refrigerant flow direction, the first ball valve is located downstream of the accumulator.

[0015] As a further improvement of the embodiment of the present invention, a filter is further provided on the third pipeline, and in the refrigerant flow direction, the filter is located downstream of the accumulator.

[0016] In a second aspect, an embodiment of the present invention further provides a performance test method for a variable frequency heat pump unit, using the above-mentioned variable frequency heat pump unit automatic control teaching experiment device, the method comprising the following steps:

[0017] Step 10) Conduct a refrigeration performance experiment. Specifically, switch the four-way valve so that the first interface and the second interface of the four-way valve are connected, and the third interface and the fourth interface of the four-way valve are connected; close the third ball valve and open the fourth ball valve;

[0018] Alternatively, a heating performance experiment is conducted. Specifically, the four-way valve is switched so that the first interface and the third interface of the four-way valve are connected, and the second interface and the fourth interface of the four-way valve are connected; the third ball valve is opened, and the fourth ball valve is closed.

[0019] As a further improvement of the embodiment of the present invention, when the refrigeration performance experiment is performed in step 10), the method further includes:

[0020] Step 20) performing a compressor variable frequency regulation experiment;

[0021] Specifically include:

[0022] Step 201) With the electronic expansion valve as the controlled object, the cooling capacity as the input quantity, and the valve opening as the output quantity, a control algorithm for the electronic expansion valve is compiled; the pressure at the inlet and outlet of the electronic expansion valve is detected in real time to obtain the relationship between the flow coefficient and the flow area of ​​the electronic expansion valve; the flow at the third interface of the evaporator and the water temperature at the third interface and the fourth interface of the evaporator are detected to obtain the cooling capacity; the parameters of the control algorithm are optimized according to the detection results until the deviation between the cooling capacity and the set value is within ±15%; the electronic expansion valve is controlled using the optimized control algorithm;

[0023] Step 202) Set multiple debugging frequencies, configure the working frequency of the variable frequency compressor as the debugging frequency one by one, detect and record the flow at the third interface of the evaporator and the water temperature at the third interface and the fourth interface of the evaporator corresponding to each debugging frequency, so as to obtain the cooling capacity corresponding to each debugging frequency, and draw a curve chart of the relationship between the cooling capacity and the compressor frequency change.

[0024] As a further improvement of the embodiment of the present invention, when the refrigeration performance experiment is performed in step 10), the method further includes:

[0025] Step 30) drawing a pressure-enthalpy diagram experiment;

[0026] Specifically, the refrigerant pressure and temperature at the inlet and outlet of the variable frequency compressor, the refrigerant pressure and temperature at the four interfaces of the regenerator, and the refrigerant pressure and temperature at the inlet and outlet of the electronic expansion valve are detected in real time, and a pressure-enthalpy diagram is drawn.

[0027] As a further improvement of the embodiment of the present invention, when the refrigeration performance experiment is performed in step 10), the method further includes:

[0028] Step 40) Experimentally draw a performance curve of the electronic expansion valve;

[0029] Specifically, the refrigerant temperature at the outlet of the electronic expansion valve and the water temperature at the third interface and the fourth interface of the evaporator are detected in real time to draw a performance curve of the electronic expansion valve.

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

[0031] The variable frequency heat pump unit automatic control teaching experiment device and performance experiment method provided by the present invention can realize refrigeration, and students can conduct refrigeration performance experiments, and can also realize heating, and students can conduct heating performance experiments. When conducting refrigeration performance experiments, students can perform state monitoring and model identification on the performance of the entire refrigeration system, and quantitatively analyze the factors affecting the performance changes of the refrigeration unit. When conducting heating performance experiments, the performance of the entire heating system can be monitored and model identified, and quantitatively analyze the factors affecting the performance changes of the heat pump unit. Students can quantitatively realize the monitoring of variable working conditions and multiple working conditions and the debugging of control algorithms, and can obtain real-time data and historical data under variable working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0033] Figure 1 It is a structural schematic diagram of a variable frequency heat pump unit automatic control teaching experimental device according to an embodiment of the present invention.

[0034] The figure includes: variable frequency compressor 1, first pressure gauge 2, needle valve 3, high pressure controller 4, mass flow meter 6, oil separator 7, second ball valve 8, low pressure controller 9, second pressure gauge 10, plate heat recovery device 11, four-way valve 12, condenser 13, axial flow fan 14, first check valve 15, second check valve 16, accumulator 17, first ball valve 18, filter 19, sight glass 20, gas-liquid separator 21, regenerator 22, electronic expansion valve 23, third check valve 24, evaporator 27, compressor inverter 29, thermometer 30, butterfly valve 31, water pump 32, water tank 33, third ball valve 34, fourth ball valve 35. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0036] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding components and features.

[0037] The embodiment of the present invention provides a variable frequency heat pump unit automatic control teaching experiment device, such as Figure 1As shown, it includes a variable frequency compressor 1, a compressor inverter 29, a four-way valve 12, a condenser 13, a regenerator 22, an electronic expansion valve 23, an evaporator 27 and a gas-liquid separator 21. The compressor inverter 29 is electrically connected to the motor of the variable frequency compressor 1, and is used to adjust the motor frequency of the variable frequency compressor 1. The outlet of the variable frequency compressor 1 is connected to the first interface of the four-way valve 12. Specifically, an oil separator 7 is connected between the outlet of the variable frequency compressor 1 and the four-way valve 12, the outlet of the variable frequency compressor 1 is connected to the inlet of the oil separator 7, and the gas outlet of the oil separator 7 is connected to the first interface of the four-way valve 12. The oil outlet of the oil separator 7 is connected to the inlet of the variable frequency compressor 1, and a second ball valve 8 is provided on the connecting pipeline. The second interface of the four-way valve 12 is connected to the first interface of the condenser 13, the second interface of the condenser 13 is connected to the first interface of the regenerator 22 through the first pipeline, the second pipeline and the third pipeline that are connected in sequence, the second interface of the regenerator 22 is connected to the inlet of the electronic expansion valve 23, the outlet of the electronic expansion valve 23 is connected to the first interface of the evaporator 27 through the fourth pipeline, the fifth pipeline and the sixth pipeline that are connected in sequence, the second interface of the evaporator 27 is connected to the third interface of the four-way valve 12, the fourth interface of the four-way valve 12 is connected to the third interface of the regenerator 22, the fourth interface of the regenerator 22 is connected to the inlet of the gas-liquid separator 21, and the outlet of the gas-liquid separator 21 is connected to the inlet of the variable frequency compressor 1. The connecting port of the first pipeline and the second pipeline is connected to the connecting port of the fourth pipeline and the fifth pipeline through the seventh pipeline, and the connecting port of the second pipeline and the third pipeline is connected to the connecting port of the fifth pipeline and the sixth pipeline through the eighth pipeline. The second pipeline is provided with a first one-way valve 15, and the flow direction of the first one-way valve 15 is the direction of flow from the connecting port between the second pipeline and the first pipeline to the connecting port between the second pipeline and the third pipeline. The seventh pipeline is provided with a second one-way valve 16, and the flow direction of the second one-way valve 16 is the direction of flow from the connecting port between the seventh pipeline and the fourth pipeline to the connecting port between the seventh pipeline and the second pipeline. The fifth pipeline is provided with a third one-way valve 24 and a second ball valve 35, and the flow direction of the third one-way valve 24 is the direction of flow from the connecting port between the fifth pipeline and the fourth pipeline to the connecting port between the fifth pipeline and the sixth pipeline. The eighth pipeline is provided with a first ball valve 34.

[0038] Among them, the first interface and the second interface of the regenerator 22 are internally connected, and the third interface and the fourth interface of the regenerator 22 are internally connected. The first interface and the second interface of the condenser 13 are internally connected for passing the refrigerant. The first interface and the second interface of the evaporator 27 are internally connected for passing the refrigerant. The third interface and the fourth interface of the evaporator 27 are internally connected, the third interface is connected to the outlet of the water tank 33 through the water inlet pipeline, and the third interface is used to pass water, and the fourth interface is connected to the inlet of the water tank 33 through the water outlet pipeline, and the fourth interface is used to output water. Preferably, a water pump 32 and a thermometer are provided on the water inlet pipeline, and a butterfly valve 31, a thermometer 30 and a flow meter are provided on the water outlet pipeline.

[0039] When the experimental device of this embodiment is used for the refrigeration performance experiment, an axial flow fan 14 is provided on one side of the condenser 13 to dissipate heat from the condenser 13. After water is pumped from the water tank 33 and heated, hot water is passed into the evaporator 27, and the evaporator 27 cools the water passed in, reflecting the refrigeration effect. By real-time detection of the temperature change of the water inlet and outlet of the evaporator 27 and the flow rate of the input water, the real-time refrigeration capacity change is obtained, and the performance of the entire refrigeration system is monitored.

[0040] When the experimental device of this embodiment is used for the heating performance experiment, water is pumped from the water tank 33 to pass cold water into the evaporator 27, and the evaporator 27 heats the passed water to reflect the heating effect. By real-time detection of the temperature change of the water inlet and outlet of the evaporator 27 and the flow rate of the input water, the real-time heating amount change is obtained, and the performance of the entire heating system is monitored.

[0041] Preferably, a pressure sensor and a temperature sensor are provided at the inlet and outlet of the variable frequency compressor 1. The pressure and temperature of the refrigerant entering the variable frequency compressor 1 and the pressure and temperature of the refrigerant exiting the variable frequency compressor 1 can be monitored in real time.

[0042] Preferably, temperature sensors and pressure sensors are provided at the four interfaces of the regenerator 22, which can monitor in real time the pressure and temperature of the liquid refrigerant entering the regenerator 22, the pressure and temperature of the gaseous refrigerant coming out of the regenerator 22, the pressure and temperature of the gaseous refrigerant entering the regenerator 22, and the pressure and temperature of the liquid refrigerant coming out of the regenerator 22.

[0043] Preferably, a pressure sensor and a temperature sensor are provided at the outlet of the electronic expansion valve 23 to monitor the pressure and temperature of the refrigerant coming out of the electronic expansion valve 23 in real time.

[0044] Preferably, the third pipeline is provided with a flow accumulator 17 and a first ball valve 18, and the ball valve 18 is located downstream of the flow accumulator 17 in the refrigerant flow direction. The flow rate of the refrigerant entering the regenerator 22 can be adjusted by the flow accumulator 17 and the first ball valve 18. Preferably, the third pipeline is also provided with a filter 19, and the filter 19 is located downstream of the flow accumulator 17 in the refrigerant flow direction. Before entering the regenerator 22, the filter 19 filters the refrigerant to remove impurities in the refrigerant. Preferably, there are two first ball valves 18, which are respectively located on both sides of the filter 19. The third pipeline is also provided with a sight glass 20, which serves as an indicator to check the flow of the refrigerant and lubricant and the water content and impurities.

[0045] Preferably, the pipeline connecting the variable frequency compressor 1 and the oil separator 7 is also provided with a first pressure gauge 2, a needle valve 3, a high pressure controller 4 and a mass flow meter 6, and the pipeline connecting the variable frequency compressor 1 and the gas-liquid separator 21 is also provided with a second pressure gauge 10, a needle valve and a low pressure controller 9. The pressure sensor is an intelligent sensor, which plays a role in measuring deviation in automatic control. The pressure gauge is a traditional thermal measuring instrument, which is mainly used to ensure the safety of the compressor. The function of the needle valve is to adjust the refrigerant gas flow. Both the high pressure controller and the low pressure controller are to protect the safety of the compressor, and automatically shut down when the limit is exceeded.

[0046] The experimental device of this embodiment can realize refrigeration, which is used for students to conduct refrigeration performance experiments, and can also realize heating, which is used for students to conduct heating performance experiments. By setting pressure sensors and temperature sensors at the inlet and outlet of the variable frequency compressor 1, setting pressure sensors and temperature sensors at the inlet and outlet of the heat regenerator 22, and setting pressure sensors and temperature sensors at the inlet and outlet of the electronic expansion valve 23, when conducting refrigeration performance experiments, students can monitor the performance of the entire refrigeration system and identify the model, and quantitatively analyze the factors affecting the performance changes of the refrigeration unit. When conducting heating performance experiments, the performance of the entire heating system can be monitored and the model can be identified, and the factors affecting the performance changes of the heat pump unit can be quantitatively analyzed. It allows students to quantitatively realize the monitoring of variable working conditions and multiple working conditions and the debugging of control algorithms, and can obtain real-time data and historical data under variable working conditions.

[0047] The embodiment of the present invention also provides a performance test method of a variable frequency heat pump unit, using the above-mentioned variable frequency heat pump unit automatic control teaching experiment device. The performance test method includes:

[0048] Step 10) A refrigeration performance experiment is performed using the experimental device of the above embodiment, and the specific process is as follows:

[0049] Switch the four-way valve 12 so that the first interface and the second interface of the four-way valve 12 are connected, and the third interface and the fourth interface are connected. Close the third ball valve 34 and open the fourth ball valve 35. Start the variable frequency compressor 1, and the low-temperature and low-pressure gaseous refrigerant and oil enter the variable frequency compressor 1. After the refrigerant is compressed, it becomes a high-temperature and high-pressure gaseous refrigerant. The high-temperature and high-pressure gaseous refrigerant and oil output by the variable frequency compressor 1 are passed into the oil separator 7, and the oil separated by the oil separator 7 is input into the variable frequency compressor 1 through the second ball valve 8. The gaseous refrigerant separated by the oil separator 7 enters the condenser 13 through the first interface and the second interface of the four-way valve 12. The high-temperature and high-pressure gaseous refrigerant is cooled and condensed into liquid refrigerant in the condenser 13. The liquid refrigerant enters the regenerator 22 through the first pipeline, the second pipeline and the third pipeline. The liquid refrigerant absorbs heat in the regenerator 22 to form a two-phase refrigerant, and then forms a low-temperature and low-pressure two-phase refrigerant after throttling and reducing the pressure by the electronic expansion valve 23. The two-phase refrigerant enters the evaporator 27 through the fourth pipeline, the fifth pipeline and the sixth pipeline. The refrigerant returns to the regenerator 22 through the fourth pipeline, the seventh pipeline, the second pipeline and the third pipeline. The refrigerant absorbs heat from the water side in the evaporator 27 and becomes gaseous, cooling the water entering the evaporator 27 to achieve refrigeration. The gaseous refrigerant enters the regenerator 22 through the third and fourth interfaces of the four-way valve 12, and the refrigerant is cooled into a two-phase refrigerant in the regenerator 22. The two-phase refrigerant is passed into the gas-liquid separator 21, and the low-temperature and low-pressure gaseous refrigerant separated by the gas-liquid separator 21 is then input into the variable frequency compressor, and continuous refrigeration is achieved in a cycle.

[0050] Alternatively, the experimental device of the above embodiment is used to conduct a refrigeration performance experiment, and the specific process is as follows:

[0051] Switch the four-way valve 12 so that the first interface and the third interface of the four-way valve 12 are connected, and the second interface and the fourth interface are connected. Open the third ball valve 34 and close the fourth ball valve 35. Start the variable frequency compressor 1, and the low-temperature and low-pressure gaseous refrigerant and oil enter the variable frequency compressor 1. The refrigerant is compressed to become a high-temperature and high-pressure gaseous refrigerant. The high-temperature and high-pressure gaseous refrigerant and oil output by the variable frequency compressor 1 are passed into the oil separator 7, and the oil separated by the oil separator 7 is input into the variable frequency compressor 1 again through the second ball valve 8. The gaseous refrigerant separated by the oil separator 7 enters the evaporator 21 through the first interface and the third interface of the four-way valve 12. The high-temperature and high-pressure gaseous refrigerant releases heat in the evaporator 21 to form a liquid refrigerant, which is added to the water passed into the evaporator 21 to achieve heating. The liquid refrigerant enters the regenerator 22 through the sixth pipeline, the eighth pipeline and the third pipeline. The liquid refrigerant absorbs heat in the regenerator 22 to form a two-phase refrigerant, and then forms a low-temperature and low-pressure two-phase refrigerant after throttling and reducing the pressure through the electronic expansion valve 23. The two-phase refrigerant enters the condenser 13 through the fourth pipeline, the seventh pipeline and the first pipeline. The refrigerant returns to the regenerator 22 through the fourth pipeline, the seventh pipeline, the second pipeline and the third pipeline. The refrigerant absorbs heat in the condenser 13 and becomes gaseous. The gaseous refrigerant enters the regenerator 22 through the second interface and the fourth interface of the four-way valve 12. The refrigerant is cooled into a two-phase refrigerant in the regenerator 22. The two-phase refrigerant is passed into the gas-liquid separator 21. The low-temperature and low-pressure gaseous refrigerant separated by the gas-liquid separator 21 is then input into the variable frequency compressor, and continuous heating is achieved over and over again.

[0052] The performance experiment method of this embodiment uses the teaching experiment device provided by this embodiment to achieve both refrigeration, which is used for students to conduct refrigeration performance experiments, and heating, which is used for students to conduct heating performance experiments.

[0053] Preferably, when the refrigeration performance experiment is performed in step 10), the method of this embodiment further includes:

[0054] Step 20) Conduct the compressor variable frequency regulation experiment, the specific process is as follows:

[0055] Step 201) The electronic expansion valve 23 is used as the controlled object, the cooling capacity is used as the input, and the valve opening is used as the output, and the control algorithm of the electronic expansion valve is written. The pressure at the inlet and outlet of the electronic expansion valve 23 is detected in real time to obtain the relationship between the flow coefficient and the flow area of ​​the electronic expansion valve. The inlet flow rate of the water side of the evaporator 27 and the water temperature at the inlet and outlet of the evaporator water side are detected to obtain the cooling capacity. The parameters of the control algorithm are optimized according to the detection results until the deviation from the set value is within ±15%. The electronic expansion valve 23 is controlled by the optimized control algorithm.

[0056] Step 202) Set multiple debugging frequencies, configure the working frequency of the variable frequency compressor 1 as the debugging frequency one by one, detect and record the inlet flow rate of the evaporator water side and the water temperature at the inlet and outlet of the evaporator water side corresponding to each debugging frequency, so as to obtain the cooling capacity corresponding to each debugging frequency, and draw a curve chart of the relationship between the cooling capacity and the compressor frequency change.

[0057] Preferably, when the refrigeration performance experiment is performed in step 10), the method of this embodiment further includes:

[0058] Step 30) Draw a pressure-enthalpy diagram experiment, the specific process is as follows:

[0059] The refrigerant pressure and temperature at the inlet and outlet of the variable frequency compressor 1, the refrigerant pressure and temperature at the four interfaces of the regenerator 22, and the refrigerant pressure and temperature at the inlet and outlet of the electronic expansion valve 23 are detected in real time, and a pressure-enthalpy diagram is drawn.

[0060] Preferably, when the refrigeration performance experiment is performed in step 10), the method of this embodiment further includes:

[0061] Step 40) Draw the performance curve experiment of the electronic expansion valve, the specific process is as follows:

[0062] The refrigerant temperature at the outlet of the electronic expansion valve 23 and the water temperature at the inlet and outlet of the water side of the evaporator are detected in real time, and the performance curve of the electronic expansion valve is drawn.

[0063] The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above specific embodiments, and the descriptions in the above specific embodiments and the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed for protection.

Claims

1. A variable frequency heat pump unit automatic control teaching experimental device, characterized in that: The invention comprises a variable frequency compressor (1), a compressor frequency converter (29), a four-way valve (12), a condenser (13), a regenerator (22), an electronic expansion valve (23), an evaporator (27) and a gas-liquid separator (21), wherein the compressor frequency converter (29) is electrically connected to a motor of the variable frequency compressor (1); the outlet of the variable frequency compressor (1) is connected to a first interface of the four-way valve (12), the second interface of the four-way valve is connected to a first interface of the condenser (13), the second interface of the condenser (13) is connected to a first interface of the regenerator (22) via a first pipeline, a second pipeline and a third pipeline which are connected in sequence, the second interface of the regenerator (22) is connected to an inlet of the electronic expansion valve (23), and the electric The outlet of the sub-expansion valve (23) is connected to the first interface of the evaporator (27) through a fourth pipeline, a fifth pipeline and a sixth pipeline which are connected in sequence; the second interface of the evaporator (27) is connected to the third interface of the four-way valve (12); the fourth interface of the four-way valve (12) is connected to the third interface of the regenerator (22); the fourth interface of the regenerator (22) is connected to the inlet of the gas-liquid separator (21); the outlet of the gas-liquid separator (21) is connected to the inlet of the variable frequency compressor (1); the connecting port of the first pipeline and the second pipeline is connected to the connecting port of the fourth pipeline and the fifth pipeline through the seventh pipeline; the connecting port of the second pipeline and the third pipeline is connected to the connecting port of the fifth pipeline and the sixth pipeline through the eighth pipeline; The first interface and the second interface of the condenser (13) are internally connected; the first interface and the second interface of the regenerator (22) are internally connected, and the third interface and the fourth interface of the regenerator (22) are internally connected; the first interface and the second interface of the evaporator (27) are internally connected; the second pipeline is provided with a first one-way valve (15), and the flow direction of the first one-way valve (15) is the direction of flow from the connecting port of the second pipeline and the first pipeline to the connecting port of the second pipeline and the third pipeline; the seventh pipeline is provided with a second one-way valve (16), and the flow direction of the second one-way valve (16) is the direction of flow from the connecting port of the seventh pipeline and the fourth pipeline to the connecting port of the seventh pipeline and the second pipeline; the fifth pipeline is provided with a third one-way valve (24) and a fourth ball valve (35), and the flow direction of the third one-way valve (24) is the direction of flow from the connecting port of the fifth pipeline and the fourth pipeline to the connecting port of the fifth pipeline and the sixth pipeline; the eighth pipeline is provided with a third ball valve (34).

2. The variable frequency heat pump unit automatic control teaching experimental device according to claim 1 is characterized in that: A pressure sensor and a temperature sensor are provided at the inlet and outlet of the variable frequency compressor (1).

3. The variable frequency heat pump unit automatic control teaching experimental device according to claim 1 is characterized in that: Temperature sensors and pressure sensors are provided at the four interfaces of the regenerator (22).

4. The variable frequency heat pump unit automatic control teaching experimental device according to claim 1 is characterized in that: A pressure sensor and a temperature sensor are provided at the outlet of the electronic expansion valve (23).

5. The variable frequency heat pump unit automatic control teaching experimental device according to claim 1 is characterized in that: The third pipeline is provided with an accumulator (17) and a first ball valve (18); in the refrigerant flow direction, the first ball valve (18) is located downstream of the accumulator (17).

6. The variable frequency heat pump unit automatic control teaching experimental device according to claim 5 is characterized in that: The third pipeline is also provided with a filter (19), and in the refrigerant flow direction, the filter (19) is located downstream of the accumulator (17).

7. A performance test method for a variable frequency heat pump unit, characterized in that: The variable frequency heat pump unit automatic control teaching experimental device according to any one of claims 1 to 6 is used, and the method comprises the following steps: Step 10) Conduct a refrigeration performance experiment. Specifically, switch the four-way valve (12) so that the first interface and the second interface of the four-way valve are connected, and the third interface and the fourth interface of the four-way valve are connected; close the third ball valve (34) and open the fourth ball valve (35); Alternatively, a heating performance experiment is conducted. Specifically, the four-way valve (12) is switched so that the first interface and the third interface of the four-way valve are connected, and the second interface and the fourth interface of the four-way valve are connected; the third ball valve (34) is opened, and the fourth ball valve (35) is closed.

8. The performance test method according to claim 7, characterized in that: When the refrigeration performance experiment is performed in step 10), the method further comprises: Step 20) performing a compressor variable frequency regulation experiment; Specifically include: Step 201) The electronic expansion valve (23) is used as the controlled object, the cooling capacity is used as the input quantity, and the valve opening is used as the output quantity, and a control algorithm for the electronic expansion valve is compiled; the pressure at the inlet and the pressure at the outlet of the electronic expansion valve (23) are detected in real time to obtain the relationship between the flow coefficient and the flow area of ​​the electronic expansion valve; the flow at the third interface of the evaporator (27) and the water temperature at the third interface and the fourth interface of the evaporator are detected to obtain the cooling capacity; the parameters of the control algorithm are optimized according to the detection results until the deviation between the cooling capacity and the set value is within ±15%; and the electronic expansion valve (23) is controlled using the optimized control algorithm; Step 202) sets a plurality of debugging frequencies, configures the working frequency of the variable frequency compressor (1) as the debugging frequency one by one, detects and records the flow rate at the third interface of the evaporator and the water temperature at the third interface and the fourth interface of the evaporator corresponding to each debugging frequency, thereby obtaining the cooling capacity corresponding to each debugging frequency, and plots a curve diagram of the relationship between the cooling capacity and the compressor frequency change.

9. The performance test method according to claim 7, characterized in that: When the refrigeration performance experiment is performed in step 10), the method further comprises: Step 30) drawing a pressure-enthalpy diagram experiment; Specifically, the refrigerant pressure and temperature at the inlet and outlet of the variable frequency compressor (1), the refrigerant pressure and temperature at the four interfaces of the regenerator (22), and the refrigerant pressure and temperature at the inlet and outlet of the electronic expansion valve (23) are detected in real time, and a pressure-enthalpy diagram is drawn.

10. The performance test method according to claim 7, characterized in that: When the refrigeration performance experiment is performed in step 10), the method further comprises: Step 40) Experimentally draw a performance curve of the electronic expansion valve; Specifically, the refrigerant temperature at the outlet of the electronic expansion valve (23) and the water temperature at the third connection and fourth interface of the evaporator are detected in real time, and a performance curve of the electronic expansion valve is drawn.

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