A heat pump plate evaporator freezing point operating condition range test system and method thereof

Abstract

The application discloses a kind of freeze point operating condition range test system of heat pump plate evaporator and method thereof, including refrigerant side test module, water side test module and control module;Refrigerant side test module is communicated with the refrigerant side structure of to-be-tested evaporator to cooperate to form refrigeration circuit, and refrigerant side test module includes compressor, condenser, expansion valve, water removal device, first flow sensor, first temperature sensor, and second temperature sensor and / or first pressure sensor;Water side test module is communicated with the water side structure of to-be-tested evaporator, and water side test module includes water inlet pipe, water outlet pipe, and water pump, second flow sensor, second pressure sensor, third pressure sensor, third temperature sensor and fourth temperature sensor.The application determines icing condition point parameter range according to the inherent heat transfer characteristics of plate evaporator, so as to facilitate heat pump air conditioning system to determine and implement control, accurately set control threshold, improve the safety, reliability and energy saving of system.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to a system and method for measuring the freezing point range of a heat pump plate evaporator. Background Technology

[0002] With increasing societal pressure to conserve energy and reduce carbon emissions, plate evaporators are increasingly being used in various types of automotive and residential heat pump air conditioning systems. Heat pump air conditioning systems using plate evaporators can significantly reduce space requirements and refrigerant charge, thus powerfully promoting the miniaturization and efficiency of heat pump air conditioning systems. However, due to the small channel volume of plate evaporators, icing is prone to occur on the water side when the evaporation pressure is low. The volume expansion caused by icing generates an expansion force exceeding 100 MPa, leading to evaporator failure. This seriously affects the safety and reliability of the heat pump air conditioning system. Therefore, understanding the icing condition range of plate evaporators is fundamental to setting control strategies for heat pump air conditioning systems and is a necessary condition for ensuring the safe and efficient operation of the system.

[0003] CN107642924B provides a method and air conditioner for preventing evaporator frost. In low-temperature cooling mode, the method acquires the condenser outer plate temperature and the compressor's continuous cooling operation time. If the condenser outer plate temperature is lower than a threshold value, or the compressor's continuous cooling operation time is greater than a threshold value, then the system enters a defrost mode. This method and air conditioner, by detecting the condenser outer plate temperature and compressor operation, can accurately determine the evaporator frost situation during low-temperature cooling, thereby effectively preventing evaporator frost and avoiding abnormal situations.

[0004] CN206890906U discloses a heat pump device for preventing evaporator icing. This device includes a compressor, a condenser, an economizer, a first throttling device, a second throttling device, an evaporator, and heating pipes. The compressor is connected to the condenser via piping. One condenser path connects to the compressor via the condenser side of the economizer, the heating pipes, the second throttling device, and the evaporator. Another condenser path connects to the compressor via the first throttling device and the evaporator side of the economizer. The heating pipes are located at the bottom of the evaporator. The coordinated components form a heating system. The heating pipes utilize the waste heat from the liquid output from the economizer to heat the evaporator, preventing incomplete defrosting due to incomplete drainage and ensuring efficient heat exchange. This structure is simple and easy to use.

[0005] As can be seen from the above technologies, existing technologies have made beneficial explorations in preventing icing and frosting on the outside of evaporators and have achieved some practical technologies. However, existing technologies still do not address the determination of the icing condition range of the heat exchanger itself. They can only make general operation strategy control based on the operating characteristics of the system and cannot make fine operation control based on the inherent characteristics of the equipment itself, so there is room for improvement. Summary of the Invention

[0006] The present invention aims to overcome the deficiencies in the prior art by providing a system and method for detecting the freezing point range of a heat pump plate evaporator. This system can determine the freezing point parameter range of the evaporator based on its inherent heat transfer characteristics, thereby facilitating the determination and implementation of control in the heat pump air conditioning system, accurately setting control thresholds, and improving the system's safety, reliability, and energy efficiency.

[0007] To achieve the above objectives, the present invention provides a heat pump plate evaporator freezing point range testing system, which is used to test the freezing condition of the evaporator under test, including a refrigerant-side testing module connected to the refrigerant side of the evaporator under test, a water-side testing module connected to the water side of the evaporator under test, and a control module.

[0008] The refrigerant-side testing module is connected to the refrigerant side of the evaporator under test to form a refrigeration circuit. The refrigerant-side testing module includes a compressor, a condenser, an expansion valve, a moisture removal device, a first flow sensor, a first temperature sensor, and a second temperature sensor and / or a first pressure sensor. The refrigerant outlet, moisture removal device, compressor, condenser, expansion valve, and refrigerant inlet of the evaporator under test are sequentially connected by pipelines. The moisture removal device is used to remove moisture carried in the refrigerant. The first flow sensor is installed on the pipeline between the condenser and the expansion valve to monitor the refrigerant flow rate in real time. The first temperature sensor is installed on the pipeline connected to the refrigerant outlet of the evaporator under test to monitor the refrigerant-side outlet temperature of the evaporator under test in real time. The second temperature sensor and / or the first pressure sensor is installed on the pipeline connected to the refrigerant inlet of the evaporator under test to monitor the refrigerant-side inlet temperature and / or refrigerant-side inlet pressure of the evaporator under test in real time.

[0009] The water-side testing module is connected to the water-side structure of the evaporator under test to form a hot water exchange circuit. The water-side testing module includes an inlet pipe, a water pump, an outlet pipe, a second flow sensor, a second pressure sensor, a third pressure sensor, a third temperature sensor, and a fourth temperature sensor. The inlet pipe and the outlet pipe are respectively connected to the water-side inlet and water-side outlet of the evaporator under test. The water pump is installed on the inlet pipe. The second pressure sensor and the third temperature sensor are both installed on the inlet pipe to monitor the water-side inlet pressure and water-side inlet temperature of the evaporator under test in real time, respectively. The second flow sensor is used to monitor the inlet flow rate of the evaporator under test in real time. The third pressure sensor and the fourth temperature sensor are both installed on the outlet pipe to monitor the water-side outlet pressure and water-side outlet temperature of the evaporator under test in real time, respectively.

[0010] The control module is connected to the first flow sensor, the compressor, and the expansion valve signals respectively. The control module controls the operating frequency of the compressor and the opening degree of the expansion valve according to the preset refrigerant flow value and the refrigerant flow fed back by the first flow sensor.

[0011] The control module is also connected to the second flow sensor and the water pump signal respectively. The control module controls the operating frequency of the water pump according to the preset water side flow value and the inlet flow fed back by the second flow sensor.

[0012] The device is further configured such that: the moisture removal device includes a device body, a heating module, a cooling module, and a dryer; the control module is connected to the heating module and the cooling module respectively to control the operation of the heating module and the cooling module.

[0013] The device body includes a refrigerant inlet pipe, a refrigerant outlet pipe, a condensing chamber, a heating chamber, a water storage chamber, a water collection pipe, and a gas transmission pipe. The condensing chamber is connected to the refrigerant inlet pipe, the water storage chamber is located below the condensing chamber and the two are connected by the water collection pipe, and the heating chamber is connected to the refrigerant outlet pipe and is connected to the water collection pipe or the water storage chamber through the gas transmission pipe.

[0014] The cooling module is installed in the condensation chamber to cool the vaporized refrigerant entering the condensation chamber and condense the water vapor it carries into condensate.

[0015] The heating module is installed inside the heating chamber to heat the vaporized refrigerant entering the heating chamber.

[0016] The dryer is installed on the gas pipeline to dry the incoming vaporized refrigerant.

[0017] The device is further configured such that the moisture removal device also includes a moisture sensor connected to the control module. The moisture sensor is installed on the gas supply line between the dryer and the heating chamber to monitor the moisture content of the vaporized refrigerant flowing through it. The control module controls the operation of the cooling module and the heating module by receiving the moisture content data fed back by the moisture sensor.

[0018] The device is further configured such that: the moisture removal device includes a semiconductor refrigeration device, the cooling module is the cold end of the semiconductor refrigeration device and / or a component connected to the cold end, and the heating module is the hot end of the semiconductor refrigeration device and / or a component connected to the hot end.

[0019] The moisture removal module is further configured to include a drain valve and a liquid level sensor that are signal-connected to the control module. The liquid level sensor is located at a predetermined height in the water storage chamber, and the drain valve is located at the drain outlet of the water storage chamber or on a pipeline connected to the drain outlet.

[0020] The water-side testing module is further configured to include a first differential pressure sensor, which is used to monitor the pressure difference between the second pressure sensor and the third pressure sensor in real time.

[0021] The refrigerant-side testing module is further configured to include a first pressure sensor, a fourth pressure sensor, and a second differential pressure sensor. The fourth pressure sensor is installed on a pipeline connected to the refrigerant outlet of the evaporator under test for real-time monitoring of the refrigerant-side outlet pressure of the evaporator under test. The second differential pressure sensor is used to monitor the pressure difference between the first pressure sensor and the fourth pressure sensor in real time.

[0022] This invention also provides a method for testing the freezing point operating range of a heat pump plate evaporator, which is implemented based on a heat pump evaporator freezing point operating condition testing system and includes the following steps:

[0023] Step 1: Connect the system to the evaporator under test and perform initialization testing;

[0024] Step 2: Turn on the hot water exchange circuit and establish water energy balance. Adjust the water inlet pressure, water inlet temperature, water outlet pressure, water inlet pressure, and water flow rate of the hot water exchange circuit to the given state.

[0025] Step 3: Turn on the refrigeration circuit and adjust its status to the design conditions of the evaporator under test;

[0026] Step 4: After the system stabilizes, adjust the state of the refrigeration circuit to the first freezing condition by adjusting the compressor and expansion valve;

[0027] Step 5: Maintain the water inlet temperature and water inlet pressure of the hot water exchange circuit, while gradually reducing the water flow rate and running for a predetermined time at each water flow rate;

[0028] Step 6: Observe the pressure difference between the inlet pressure and outlet pressure on the water side within a predetermined time under the corresponding water flow rate. If the pressure difference does not change much within the predetermined time, it indicates that no freezing condition has occurred. If the pressure difference suddenly increases within the predetermined time, it indicates that freezing condition has occurred. Record the data at the first freezing condition point.

[0029] Step 7: Repeat steps 4 to 6 to test the evaporator under the second to Nth icing conditions and record the corresponding icing condition data.

[0030] Further steps include: Step 8: Combining multiple sets of icing condition data, plotting a three-dimensional coordinate diagram of the icing condition range of the evaporator under test.

[0031] Further settings include: the scheduled time for steps five and six is ​​20-30 minutes.

[0032] Further settings include: in step six, the differential pressure suddenly increases as follows: the differential pressure before the point of sudden increase is always 100%-110% of the initial state, and the differential pressure at the point of sudden increase is 125%-140% of the initial state.

[0033] Further settings include: the freezing point data in step seven includes the water-side inlet temperature, inlet flow rate, and refrigerant-side inlet temperature or refrigerant-side inlet pressure.

[0034] Compared with existing technologies, the testing system of this invention has a simple and reasonable structure. It can determine the icing condition parameter range of the evaporator based on the inherent heat transfer characteristics of the plate evaporator, thereby facilitating the determination and implementation of heat pump air conditioning system control, accurately setting control thresholds, and improving the system's safety, reliability, and energy efficiency. The corresponding testing method is also simple and efficient, and the data can intuitively reflect whether ice has formed inside the evaporator. At the same time, a special moisture removal device is used, which is suitable for destructive testing of the evaporator, ensuring the reusability and stable operation of the testing system. It can achieve intelligent control by monitoring the water content of the refrigerant through a moisture sensor. By controlling the cooling module to reduce its surface temperature to the dew point temperature, the moisture in the refrigerant can be condensed into condensate and guided into the water storage chamber for storage or discharge. The refrigerant will then enter the heating chamber, be heated by the heating module, and re-enter the refrigerant circuit, effectively separating the moisture mixed in the refrigerant to achieve effective protection of the system. Attached Figure Description

[0035] Figure 1This is a schematic diagram of the structure of a heat pump plate evaporator freezing point range testing system according to the present invention;

[0036] Figure 2 This is a schematic diagram of the moisture removal device;

[0037] Figure 3 This is a block logic diagram of a method for testing the freezing point range of a heat pump plate evaporator.

[0038] The following reference numerals are marked on the accompanying drawings:

[0039] 10. Refrigerant-side testing module; 11. Compressor; 12. Condenser; 13. Expansion valve; 14. First flow sensor; 15. First temperature sensor; 16. Second temperature sensor; 17. First pressure sensor; 18. Moisture removal device; 181. Refrigerant inlet pipe; 182. Refrigerant outlet pipe; 183. Condensation chamber; 184. Heating chamber; 185. Water storage chamber; 186. Water collection pipe; 187. Gas transmission pipe; 188. Semiconductor refrigeration device; 1881. Cooling module; 1882. Heating module; 189. Dryer; 181 0. Moisture sensor; 1811. Drain valve; 1812. Liquid level sensor; 19. Fourth pressure sensor; 110. Second differential pressure sensor; 20. Water-side test module; 21. Inlet pipe; 22. Water pump; 23. Outlet pipe; 24. Second flow sensor; 25. Third temperature sensor; 26. Fourth temperature sensor; 27. Second pressure sensor; 28. Third pressure sensor; 29. ​​First differential pressure sensor; 30. Control module; 40. Evaporator under test; 41. Refrigerant outlet; 42. Refrigerant inlet; 43. Water-side outlet; 44. Water-side inlet. Implementation

[0040] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0041] This invention provides a system for detecting the freezing point condition of a heat pump plate evaporator. Figure 1 As shown, it is applicable to the icing condition of the test plate evaporator 40, and includes a refrigerant-side test module 10 for connecting to the refrigerant side of the evaporator 40, a water-side test module 20 for connecting to the water side of the evaporator 40, and a control module 30 for controlling the operation of the refrigerant-side test module and the water-side test module 20.

[0042] In this embodiment, the refrigerant-side testing module 10 includes a compressor 11, a condenser 12, an expansion valve 13, a moisture removal device 18, a first flow sensor 14, a first temperature sensor 15, and a second temperature sensor 16 and / or a first pressure sensor 17. The refrigerant outlet 41 of the evaporator 40 under test, the moisture removal device 18, the compressor 11, the condenser 12, the expansion valve 13, and the refrigerant inlet 42 of the evaporator 40 under test are sequentially connected via pipelines to form a refrigeration circuit. The moisture removal device 18 removes moisture carried in the refrigerant to prevent damage to the evaporator 40 during testing, thus preventing water from entering the refrigerant side and damaging the components of the refrigerant-side testing module 10, ensuring stable operation of the refrigerant-side testing module 10. The first flow sensor 14, a first temperature sensor 15, a second temperature sensor 16, and / or a first pressure sensor 17 are also included. A flow sensor 14 is installed on the pipeline between the condenser 12 and the expansion valve 13 to monitor the refrigerant flow rate in real time. A first temperature sensor 15 is installed on the pipeline connected to the refrigerant outlet 41 of the evaporator 40 under test to monitor the refrigerant outlet temperature of the evaporator 40 under test in real time. A second temperature sensor 16 and / or a first pressure sensor 17 are installed on the pipeline connected to the refrigerant inlet 42 of the evaporator 40 under test to monitor the refrigerant inlet temperature and / or refrigerant inlet pressure of the evaporator 40 under test in real time. The control module 30 is connected to the first flow sensor 14, the compressor 11 and the expansion valve 13 respectively. The control module 30 controls the operating frequency of the compressor 11 and the opening degree of the expansion valve 13 according to the preset refrigerant flow rate value and the refrigerant flow rate fed back by the first flow sensor 14.

[0043] Preferably, the refrigerant-side testing module 10 includes a first pressure sensor 17, a fourth pressure sensor 19, and a second differential pressure sensor 110. The fourth pressure sensor 19 is installed on the pipeline connected to the refrigerant outlet 41 of the evaporator 40 under test to monitor the refrigerant-side outlet pressure of the evaporator 40 under test in real time. The second differential pressure sensor 110 is used to monitor the pressure difference between the first pressure sensor 17 and the fourth pressure sensor 19 in real time, so that the pressure difference data of the refrigerant side can be obtained more directly.

[0044] In the above scheme, to ensure the stable operation and continuous use of the refrigerant-side testing module 10, the moisture removal device 18 is preferably a device that can efficiently remove moisture from the refrigerant and discharge the moisture; the moisture removal device 18 is as follows: Figure 2As shown, the device includes a main body, a heating module 1882, a cooling module 1881, and a dryer 189. A control module 30 is signal-connected to both the heating module 1882 and the cooling module 1881 to control their operation. The main body includes a refrigerant inlet pipe 181, a refrigerant outlet pipe 182, a condensing chamber 183, a heating chamber 184, a water storage chamber 185, a water collection pipe 186, and a gas transmission pipe 187. The condensing chamber 183 is connected to the refrigerant inlet pipe 181, and the water storage chamber 185 is located below the condensing chamber 183 and the two are connected. The heating chamber 184 is connected to the refrigerant outlet pipe 182 via the water collection pipe 186, and is connected to the water collection pipe 186 or the water storage chamber 185 via the gas supply pipe 187; the cooling module 1881 is installed in the condensing chamber 183 to cool the vaporized refrigerant entering the condensing chamber 183 and condense the water vapor it carries into condensate; the heating module 1882 is installed in the heating chamber 184 to heat the vaporized refrigerant entering the heating chamber 184; the dryer 189 is installed on the gas supply pipe 187 to dry the vaporized refrigerant flowing in.

[0045] Preferably, the moisture removal device 18 also includes a moisture sensor 1810 connected to the control module 30. This moisture sensor 1810 is installed on the gas supply line 187 between the dryer 189 and the heating chamber 184 to monitor the moisture content in the dried refrigerant. The control module 30 controls the operation of the cooling module 1881 and the heating module 1882 based on the moisture content data fed back by the moisture sensor 1810. If the moisture content data fed back by the moisture sensor 1810 is 0, then there is no moisture in the refrigerant, and neither the heating module 1882 nor the cooling module 1881 works. If the moisture content data fed back by the moisture sensor 1810 is greater than 0 or greater than a certain value, the control module 30 controls the cooling module 1881 and the heating module 1882 to work. The cooler operates to lower its surface temperature to the dew point temperature, thus allowing the vaporized refrigerant to contact the cooling module 1881, causing the moisture it carries to condense into condensate. The condensate flows along the water collection line 186. The vaporized refrigerant flows into the water storage chamber 185 and then flows along the gas supply line 187 into the heating chamber 184, where it is heated to the initial entry temperature or the set temperature by the heater. Preferably, the moisture removal module also includes a drain valve 1811 and a liquid level sensor 1812 connected to the control module 30. A drain outlet is provided at the bottom of the water storage chamber 185, and the drain valve 1811 is correspondingly located at the drain outlet or on the pipeline connected to the drain outlet. The liquid level sensor 1812 is located at a set height position in the water storage chamber 185. If the water level in the water storage chamber 185 reaches the liquid level sensor 1812, the liquid level sensor 1812 sends a signal to the control module 30 to control the drain valve 1811 to open and drain the water until the drain valve 1811 operates for a set time or the water in the water storage chamber 185 is completely drained, after which it automatically closes. This ensures that the moisture removal device 18 can be used continuously for destructive testing of the evaporator 40 under test, ensuring the stable and continuous operation of the test system.

[0046] Preferably, the moisture removal device 18 further includes a semiconductor cooling device 188, a cooling module 1881 which is the cold end of the semiconductor cooling device 188 and a mesh or grid-like component connected to the cold end to increase the contact area, and a heating module 1882 which is the hot end of the semiconductor cooling device 188 and a mesh or grid-like component connected to the hot end to increase the contact area.

[0047] In this embodiment, the water-side testing module 20 is connected to the water-side structure of the evaporator 40 under test to form a hot water exchange circuit. The water-side testing module 20 includes an inlet pipe 21, a water pump 22, an outlet pipe 23, a second flow sensor 24, a second pressure sensor 27, a third pressure sensor 28, a third temperature sensor 25, and a fourth temperature sensor 26. The inlet pipe 21 and the outlet pipe 23 are respectively connected to the water-side inlet 44 and the water-side outlet 43 of the evaporator 40 under test. The water pump 22 is installed on the inlet pipe 21. The second pressure sensor 27 and the third temperature sensor 25 are both installed on the inlet pipe 21 to separate the flow rate and flow rate. The second flow sensor 24 is used to monitor the inlet water flow of the evaporator 40 under test in real time. The third pressure sensor 28 and the fourth temperature sensor 26 are both installed on the outlet pipe 23 to monitor the outlet water pressure and outlet water temperature of the evaporator 40 under test in real time, respectively. The control module 30 is connected to the second flow sensor 24 and the water pump 22 respectively. The control module 30 controls the operating frequency of the water pump 22 according to the preset water flow value and the inlet water flow fed back by the second flow sensor 24 to control the inlet water flow in the heat exchange pipeline to reach the preset value.

[0048] In the above scheme, the water-side test module 20 also includes a first differential pressure sensor 29, which is used to monitor the pressure difference between the second pressure sensor 27 and the third pressure sensor 28 in real time, so that the pressure difference data of the water side can be obtained more directly.

[0049] This invention also provides a method for testing the freezing point condition of a heat pump plate evaporator, which is implemented based on the aforementioned heat pump evaporator freezing point condition testing system, such as... Figure 3 As shown, it includes:

[0050] Step 1: Connect the system to the evaporator 40 under test and perform initialization testing;

[0051] Step 2: Turn on the hot water exchange circuit and establish water energy balance. Adjust the water inlet pressure, water inlet temperature, water outlet pressure, water inlet pressure, and water flow rate of the hot water exchange circuit to the given state.

[0052] Step 3: Turn on the refrigeration circuit and adjust its status to the design conditions of the evaporator 40 under test;

[0053] Step 4: After the system stabilizes, adjust the state of the refrigeration circuit to the first freezing condition by adjusting the compressor 11 and the expansion valve 13 (the freezing condition is the condition where the water temperature can reach 0°C or below and freeze by adjusting the saturation temperature of the refrigeration circuit, i.e., the refrigerant outlet temperature).

[0054] Step 5: Maintain the water inlet temperature and water inlet pressure of the hot water exchange circuit, while gradually reducing the water flow rate and running for a predetermined time at each water flow rate. This predetermined time is generally selected as 20-30 minutes.

[0055] Step Six: Observe the pressure difference between the inlet and outlet pressures on the water side within a predetermined time under the corresponding water flow rate. If the pressure difference does not change significantly within the predetermined time (20-30 minutes), i.e., the pressure difference remains within 100%-110% of the initial state, then no freezing condition has occurred. If the pressure difference suddenly increases within the predetermined time (20-30 minutes), i.e., the pressure difference remains relatively constant within 100%-110% of the initial state before the sudden change, and then suddenly increases to 125%-140% of the initial state at the point of sudden change, then freezing condition has occurred. Record the data at the first freezing condition point.

[0056] Step 7: Repeat steps 4 to 6 to test the evaporator 40 under the second to Nth freezing conditions respectively, and record the corresponding freezing condition data. The freezing condition data includes the water-side inlet temperature, water flow rate, and refrigerant-side inlet temperature or refrigerant-side inlet pressure.

[0057] Step 8: Combine multiple sets of icing condition data to draw a three-dimensional coordinate diagram of the icing condition range of the evaporator 40 under test.

[0058] Compared with existing technologies, the testing system of this invention has a simple and reasonable structure. It can determine the icing condition parameter range of the evaporator based on the inherent heat transfer characteristics of the plate evaporator, thereby facilitating the determination and implementation of heat pump air conditioning system control, accurately setting control thresholds, and improving the system's safety, reliability, and energy efficiency. The corresponding testing method is also simple and efficient, and the data can intuitively reflect whether ice has formed inside the evaporator. At the same time, a special moisture removal device is used, which is suitable for destructive testing of the evaporator, ensuring the reusability and stable operation of the testing system. It can achieve intelligent control by monitoring the water content of the refrigerant through a moisture sensor. By controlling the cooling module to reduce its surface temperature to the dew point temperature, the moisture in the refrigerant can be condensed into condensate and guided into the water storage chamber for storage or discharge. The refrigerant will then enter the heating chamber, be heated by the heating module, and re-enter the refrigerant circuit, effectively separating the moisture mixed in the refrigerant to achieve effective protection of the system.

[0059] The above-disclosed embodiments are merely examples of the present invention. However, the present invention is not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for testing the freezing point operating range of a heat pump plate evaporator, characterized in that it is implemented based on a heat pump plate evaporator freezing point operating condition testing system; The heat pump plate evaporator freezing point test system is used to test the freezing condition of the evaporator under test. It includes a refrigerant-side test module connected to the refrigerant side of the evaporator under test, a water-side test module connected to the water side of the evaporator under test, and a control module. in, The refrigerant-side testing module is connected to the refrigerant side of the evaporator under test to form a refrigeration circuit. The refrigerant-side testing module includes a compressor, a condenser, an expansion valve, a moisture removal device, a first flow sensor, a first temperature sensor, and a second temperature sensor and / or a first pressure sensor. The refrigerant outlet, moisture removal device, compressor, condenser, expansion valve, and refrigerant inlet of the evaporator under test are sequentially connected by pipelines. The moisture removal device is used to remove moisture carried in the refrigerant. The first flow sensor is installed on the pipeline between the condenser and the expansion valve to monitor the refrigerant flow rate in real time. The first temperature sensor is installed on the pipeline connected to the refrigerant outlet of the evaporator under test to monitor the refrigerant-side outlet temperature of the evaporator under test in real time. The second temperature sensor and / or the first pressure sensor is installed on the pipeline connected to the refrigerant inlet of the evaporator under test to monitor the refrigerant-side inlet temperature and / or refrigerant-side inlet pressure of the evaporator under test in real time. The water-side testing module is connected to the water-side structure of the evaporator under test to form a hot water exchange circuit. The water-side testing module includes an inlet pipe, a water pump, an outlet pipe, a second flow sensor, a second pressure sensor, a third pressure sensor, a third temperature sensor, and a fourth temperature sensor. The inlet pipe and the outlet pipe are respectively connected to the water-side inlet and water-side outlet of the evaporator under test. The water pump is installed on the inlet pipe. The second pressure sensor and the third temperature sensor are both installed on the inlet pipe to monitor the water-side inlet pressure and water-side inlet temperature of the evaporator under test in real time, respectively. The second flow sensor is used to monitor the inlet flow rate of the evaporator under test in real time. The third pressure sensor and the fourth temperature sensor are both installed on the outlet pipe to monitor the water-side outlet pressure and water-side outlet temperature of the evaporator under test in real time, respectively. The control module is connected to the first flow sensor, the compressor, and the expansion valve signals respectively. The control module controls the operating frequency of the compressor and the opening degree of the expansion valve according to the preset refrigerant flow value and the refrigerant flow fed back by the first flow sensor. The control module is also connected to the second flow sensor and the water pump signal respectively. The control module controls the operating frequency of the water pump according to the preset water side flow value and the inlet flow fed back by the second flow sensor. The testing method includes the following steps: Step 1: Connect the system to the evaporator under test and perform initialization testing; Step 2: Turn on the hot water exchange circuit and establish water energy balance. Adjust the water-side inlet pressure, water-side inlet temperature, water-side outlet pressure, and inlet flow rate of the hot water exchange circuit to the given state. Step 3: Turn on the refrigeration circuit and adjust its status to the design conditions of the evaporator under test; Step 4: After the system has stabilized, adjust the state of the refrigeration circuit to the first freezing condition by adjusting the compressor and expansion valve; Step 5: Maintain the water inlet temperature and water inlet pressure of the hot water exchange circuit, while gradually reducing the water flow rate and running for a predetermined time at each water flow rate; Step 6: Observe the pressure difference between the inlet pressure and outlet pressure on the water side within a predetermined time under the corresponding water flow rate. If the pressure difference does not change much within the predetermined time, it indicates that no freezing condition has occurred. If the pressure difference suddenly increases within the predetermined time, it indicates that freezing condition has occurred. Record the data at the first freezing condition point. Step 7: Repeat steps 4 to 6 to test the evaporator under the second to Nth icing conditions and record the corresponding icing condition data. Step 8: Combine multiple sets of icing condition data to draw a three-dimensional coordinate diagram of the icing condition range of the evaporator under test.

2. The method for testing the freezing point range of a heat pump plate evaporator according to claim 1, characterized in that, The scheduled time for steps five and six is ​​20-30 minutes.

3. The method for testing the freezing point range of a heat pump plate evaporator according to claim 1, characterized in that, In step six, the pressure difference suddenly increases as follows: the pressure difference before the point of sudden increase is always 100%-110% of the initial state, and the pressure difference at the point of sudden increase is 125%-140% of the initial state.

4. The method for testing the freezing point operating range of a heat pump plate evaporator according to claim 1, characterized in that, The freezing point data in step seven includes the water-side inlet temperature, inlet flow rate, and refrigerant-side inlet temperature or refrigerant-side inlet pressure.

5. The method for testing the freezing point range of a heat pump plate evaporator according to claim 1, characterized in that, The moisture removal device includes a device body, a heating module, a cooling module, and a dryer. The control module is connected to the heating module and the cooling module respectively to control the operation of the heating module and the cooling module. The device body includes a refrigerant inlet pipe, a refrigerant outlet pipe, a condensing chamber, a heating chamber, a water storage chamber, a water collection pipe, and a gas transmission pipe. The condensing chamber is connected to the refrigerant inlet pipe, the water storage chamber is located below the condensing chamber and the two are connected by the water collection pipe, and the heating chamber is connected to the refrigerant outlet pipe and is connected to the water collection pipe or the water storage chamber through the gas transmission pipe. The cooling module is installed in the condensation chamber to cool the vaporized refrigerant entering the condensation chamber and condense the water vapor it carries into condensate. The heating module is installed inside the heating chamber to heat the vaporized refrigerant entering the heating chamber. The dryer is installed on the gas pipeline to dry the incoming vaporized refrigerant.

6. The method for testing the freezing point range of a heat pump plate evaporator according to claim 5, characterized in that, The moisture removal device also includes a moisture sensor connected to the control module. The moisture sensor is installed on the gas supply line between the dryer and the heating chamber to monitor the moisture content of the vaporized refrigerant flowing through it. The control module controls the operation of the cooling module and the heating module by receiving the moisture content data fed back by the moisture sensor.

7. The method for testing the freezing point range of a heat pump plate evaporator according to claim 5, characterized in that, The moisture removal device also includes a drain valve and a liquid level sensor that are connected to the control module. The liquid level sensor is located at a predetermined height in the water storage chamber, and the drain valve is located at the drain outlet of the water storage chamber or on a pipeline connected to the drain outlet.

8. The method for testing the freezing point range of a heat pump plate evaporator according to claim 1, characterized in that, The water-side testing module also includes a first differential pressure sensor, which is used to monitor the pressure difference between the second pressure sensor and the third pressure sensor in real time.

9. The method for testing the freezing point range of a heat pump plate evaporator according to claim 1, characterized in that, The refrigerant-side testing module includes a first pressure sensor, a fourth pressure sensor, and a second differential pressure sensor. The fourth pressure sensor is installed on a pipeline connected to the refrigerant outlet of the evaporator under test to monitor the refrigerant-side outlet pressure of the evaporator under test in real time. The second differential pressure sensor is used to monitor the pressure difference between the first pressure sensor and the fourth pressure sensor in real time.

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