Wide-working-condition multi-refrigerant high-precision compressor refrigerating capacity testing method and device

Abstract

The invention discloses a wide-working-condition multi-refrigerant high-precision compressor refrigerating capacity testing method and device. The wide-working-condition multi-refrigerant high-precision compressor refrigerating capacity testing device comprises a measurement and control system, a testing software system and a refrigerating system. The measurement and control system is matched with the measurement and control software system to measure, judge, control, establish a database, process data and perform man-machine interaction on the refrigeration system; the test software system is used for realizing the functions of parameter setting, data visualization, system control, safety alarm and report storage; the refrigeration system comprises a test main system and a test environment system. The test main system comprises a compressor to be tested, an oil separation system, a condenser, a subcooler, a flowmeter, an expansion valve and a calorimeter; the test environment system provides a tested environment for the test main system and comprises a cooling system, a heater and an air circulation system; according to the invention, corresponding control parameters are adjusted according to different characteristics of different refrigerants, so that the testing device can adapt to testing of refrigerating systems of various working media, and a multi-refrigerant testing function is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of manufacturing refrigeration compressor performance testing equipment, and specifically relates to a high-precision compressor refrigeration capacity testing method and device under wide working conditions and multiple refrigerants. Background Art

[0002] With the development of the global economy and the improvement of people's living standards, the application scenarios of refrigeration equipment in various fields are constantly expanding. Refrigeration technology not only plays an important role in daily life such as home air conditioners and refrigerators, but also shows its indispensable value in many fields such as food preservation, medical refrigeration, industrial production, etc. Therefore, the performance research of refrigeration compressors has become particularly important to meet the growing needs and challenges.

[0003] As global energy becomes increasingly scarce, governments around the world have gradually strengthened their supervision of energy efficiency, especially in terms of the energy efficiency of refrigeration equipment. Many countries and regions have successively introduced energy efficiency standards for refrigeration equipment, requiring newly produced refrigeration compressors to achieve a specific energy efficiency ratio (COP).

[0004] The refrigeration industry is developing rapidly. The compressor is the core of the refrigeration industry and the heart of refrigeration equipment. The performance of the compressor is directly related to the performance of the refrigeration equipment. In recent years, the requirements for it have also been greatly improved. Although compressor technology innovations are endless, the research and development of the corresponding compressor refrigeration capacity test device is relatively backward. In actual use, the working conditions and refrigerant use of the compressor are diverse, and the refrigeration capacity test device used on my country's compressor production line has the problem of unstable test accuracy due to the imperfect system and structure. In order to meet the higher requirements of compressor development, it is of great significance to develop a high-precision compressor refrigeration capacity test device with wide working conditions and multiple refrigerants for the operation of the compressor under different working conditions and using different refrigerants. It aims to solve the problems of insufficient comprehensiveness and insufficient accuracy of compressor refrigeration capacity testing. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method and device for testing the refrigeration capacity of a compressor with high precision under a wide range of operating conditions and multiple refrigerants.

[0006] The present invention provides the following technical solution: A high-precision compressor refrigeration capacity testing device with wide operating conditions and multiple refrigerants includes a measurement and control system, a test software system and a refrigeration system.

[0007] The refrigeration system includes a test main system and a test environment system. The test main system is composed of a tested compressor, an oil separation system, a condenser, a subcooler, a flow meter, an expansion valve, a calorimeter, a temperature and pressure detection sensor, and an auxiliary switch valve; the test environment system includes an environmental chamber, an environmental refrigeration unit, a gas-controlled expansion valve, an evaporator, a heater, and a circulating fan.

[0008] The test environment system provides a test environment for the main test system, provides a low temperature environment for the test system through the environmental refrigeration unit, and then heats and controls the temperature through the electrically controlled heating tube, so as to control the ambient temperature within the specified range of the working conditions. The operation of the environmental circulation fan allows the airflow to be distributed in the environmental room through the circulating air duct, providing the required temperature environment for the running system. Due to the large size of the equipment, the airflow blown out by the fan is easy to circulate downward to the other end of the equipment after being blown out horizontally from the air duct outlet, thus forming a hollow circulation, which seriously affects the accuracy and stability of the environmental temperature control. In order to make the airflow in the environmental chamber evenly distributed, the following structural innovations are made in the environmental chamber: (1) Two longitudinal diverter plates are designed on the upper wall parallel to the air outlet. The airflow density near the air outlet is larger and the airflow density far from the air outlet is relatively smaller. Therefore, when designing, the vents of the diverter plate near the air outlet are densely distributed while those far from the air outlet are sparsely distributed to ensure that the lateral airflow can be evenly diverted downward; (2) A plate is installed horizontally below the diverter plate, and air holes of uniform size are evenly distributed on the plate. The stratified airflow is then diverted downward through the diverter plate. The wind porous plate forms an environmental temperature field with uniform and stable wind speed. The same porous plate is used to separate a bottom space under the environmental chamber. The uniform temperature laminar flow from top to bottom flows out from the lower wind-dispersing porous plate into the circulating air duct after the temperature is controlled in the temperature chamber; (3) The upper and lower wind-dispersing porous plates not only need to uniformly control the temperature field in the temperature chamber and form a circulating air duct, but the lower wind-dispersing porous plate should also play a role in fixing the compressor under test and preventing oil accumulation at the oil injection point. Therefore, when designing the lower wind-dispersing porous plate, the groove and oil drain port of the compressor under test should be designed at the corresponding position. The above-mentioned improvement of the environmental chamber enables the wind flow blown out from the fan from the circulating air duct to flow from top to bottom in a graded manner. The graded wind flow is evenly diverted again through the lower wind-dispersing porous plate, and the hollow circulation formed by the single downward flow at the beginning becomes a uniformly distributed and dense downward temperature laminar flow. The wind flow flowing down from the upper wind-dispersing porous plate passes through the temperature-controlled area evenly, then flows out from the bottom, enters the temperature-controlled room through the return channel, and returns to the fan inlet at the top after temperature control to complete the air flow cycle.

[0009] In order to reduce the vibration and noise caused by friction during operation, the compressor needs a certain amount of lubricating oil inside. However, part of the lubricating oil will enter the refrigeration system as the compressor is running. This part of the lubricating oil entering the system will increase the flow resistance of the refrigerant, weaken the heat exchange effect of the refrigerant, affect the effectiveness of the compressor lubrication, and occupy the refrigerant volume, thereby affecting the compressor's refrigeration capacity and energy efficiency ratio. In order to reduce the oil content in the pipeline and reduce the above-mentioned effects, an oil separation device is designed at the exhaust end of the compressor to separate the lubricating oil discharged from the compressor and return it to the compressor. The above-mentioned oil separation system is added to the exhaust end of the compressor, and the following design is made: (1) An oil separator is connected to the exhaust end of the compressor. The oil separator and the compressor are connected to work through a manual valve. The switch valve selects whether to use the oil separation function; (2) The compressor needs a certain amount of lubricating oil to ensure its normal operation. The lubricating oil inside the compressor will enter the system as it runs. Long-term accumulation will cause serious internal wear. In order to reduce this impact, an oil return pipeline and oil return valve are added between the oil separator and the process port side of the compressor. During and after the test, the separated lubricating oil can flow back into the compressor through the oil return valve; (3) Oil separation requires a certain oil separation temperature. A wall-mounted insulation box is designed to place the oil separator. The pipeline interface is sealed with insulation cotton. The interior is designed with a condenser, an environmental heater, an air circulation device and an over-temperature protection probe. The temperature in the box is kept stable by controlling the heating power. After making the above changes, the lubricating oil leaked from the exhaust end of the compressor will be separated from the refrigerant by the oil separator and returned to the compressor after each test run. This effectively reduces the impact of lubricating oil particles in the refrigeration system while ensuring the lubrication performance of the compressor. The oil separation box can maintain a stable oil separation environment temperature, so that the oil and gas separation function of the oil separator can operate stably.

[0010] The main components of the test main system in the above refrigeration system include condenser, subcooler, flowmeter, expansion valve and calorimeter. After the refrigerant passes through the compressor to work, it forms high-temperature and high-pressure gas, and then passes through the condenser and subcooler to become high-pressure subcooled liquid. Condensation temperature and subcooling temperature are very important condition parameters for the compressor refrigeration test. In order to improve the working stability of the compressor test system, the designed condenser shell and subcooler shell are composed of a steel inner tube, an insulation layer and a plastic-sprayed outer shell, and the connection with the external pipeline is sealed with insulation cotton. It is cooled by an independent condensing refrigeration unit and a subcooling refrigeration unit, and the condensing temperature and subcooling temperature are accurately and stably controlled by the PID heating control of the heating pipe in the tank. In order to prevent the condensation and subcooling control from interfering with each other and improve the working stability of the system, the condensation and subcooling refrigeration in this system are completely independent, and each is realized by a set of refrigeration units with air-cooled condensers, including a compressor, an air-cooled condenser, a liquid receiver, a drying filter, a return air cooler and an adjustable gas-controlled expansion valve.

[0011] The designed refrigeration compressor cooling capacity test device is designed and built based on the measurement principle of the second refrigerant calorimeter method. The refrigerant is discharged from the subcooler to form a supercooled refrigerant liquid, and then passes through the expansion valve to become low-temperature and low-pressure wet steam. It then absorbs a large amount of heat through the calorimeter and evaporates. The heat absorbed in the calorimeter is measured to reflect the cooling capacity of the compressor and compared with the cooling capacity measured by the flow meter. In order to measure the cooling capacity more accurately, the following considerations and improvements are made when designing the calorimeter in the system: (1) The calorimeter is filled with a certain mass of low-boiling-point second refrigerant, and the corresponding saturation pressure at the required ambient temperature is relatively high. Therefore, the calorimeter not only needs to have thermal insulation but also a certain pressure resistance. The calorimeter shell consists of a pressure-resistant stainless steel inner cylinder, a foam insulation layer formed by overall polyurethane foaming, and a spray-coated outer shell that can reduce external heat radiation. The insulation board is placed above and below the inner cylinder, and the mounting column is connected to the insulation board, which isolates heat transfer. The gas-controlled expansion valve is installed inside the calorimeter to prevent the refrigerant from exchanging heat with the outside world during the expansion stage, which may cause heat leakage from the valve body. (2) When the refrigerant passes through the evaporating coil in the calorimeter, the flow resistance is large due to the internal bends in the pipe. The oil particles in the refrigerant are easily accumulated in the evaporating coil. When designing and constructing the flow channel in the calorimeter, the refrigerant inlet is designed above the calorimeter. The refrigerant first expands through the expansion valve and then fully exchanges heat through the evaporating coil from top to bottom. In this way, the oil particles in the refrigerant are not easy to remain in the curved coil. After the flow channel in the calorimeter is optimized, the oil accumulation in the evaporation circuit can be effectively reduced, and the system stability and refrigerant heat exchange efficiency can be improved. (3) The amount of heat in the calorimeter tank can reflect the cooling capacity of the compressor. It uses a DC power supply for heating, and the output voltage of the DC power supply is controlled by a program to achieve the heating adjustment of the calorimeter tank. Compared with AC heating, the advantages of DC heating are more stable output power, more accurate temperature control, and more precise electric energy accumulation, which can greatly improve the test accuracy of the compressor cooling capacity.

[0012] The measurement and control system cooperates with the measurement and control software to undertake the tasks of measurement, judgment, control, database establishment, data processing and human-computer interaction of the refrigeration system under test. The measurement and control system is an "industrial computer + industrial board" mode. The four serial interfaces of the industrial computer are used to measure the cold and hot resistance values ​​of the compressor motor windings, operating power, current, power factor, calorimeter heating energy, variable frequency drive three-phase output electrical parameters and flow meter flow, etc.; the analog input interface is used to measure analog signals such as external system temperature, system pressure, unit current, system vacuum and gas concentration; the high-speed data acquisition card is used to sample the compressor bus current and calculate the compressor speed and measure the compressor suction and exhaust pulsation; the input and output interface card is used to detect the limit signal, pressure and temperature alarm signal and other input signals of external mechanical movement, and its output function is used to realize the control of the external heating system, refrigeration system, system pneumatic valves and other actuators; two-channel serial interface card, one channel and the variable frequency compressor speed adjustment pulse table form a master-slave bus network, which is used to send the frequency signal value corresponding to the variable frequency compressor speed to the pulse table; the other channel connects the thermocouple module and the analog output module.

[0013] The operating conditions of the compressor controlled by the measurement and control system include evaporation temperature (-60~20℃), condensation temperature (35~80)℃, supercooling temperature (25~65℃), rotation speed (50~6500rpm), ambient temperature (20~50℃), suction temperature (20~50℃) and oil separation chamber temperature (40~75℃). In order to meet the measurement of multiple operating points of the compressor, the test device has a wide range of operating condition control. Sensors with corresponding measurement ranges and accuracy are installed at each test point to achieve multi-operating point control. In these controlled test conditions, the evaporation temperature, condensation temperature, supercooling temperature and suction temperature are all indirectly controlled by controlling the pressure. The corresponding relationship between the saturation temperature and pressure of different refrigerants is different. The temperature and pressure corresponding control parameters of several refrigerants are added to the measurement and control system to realize the testing of refrigeration systems of multiple working fluids such as R600a, R290a, R134a, R1234yf, etc., to meet the multi-refrigerant function of the device.

[0014] The measurement and control software system of the refrigeration compressor high-precision refrigeration capacity test device includes functions such as operator information and parameter settings, real-time data acquisition visualization, system working condition control test, data transmission, report printing and storage, historical data query and curve display and alarm signal. The parameter settings include operator information, parameter settings, setting default values ​​for each test, and visualization of each test result; the system control test conditions are controlled by a computer, including standard working condition test, multi-point working condition test, suction and exhaust pulsation test, and simultaneous control of the switch of each valve.

[0015] By adopting the above technology, compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1) In the device of the present invention, when the environmental circulation fan in the environmental room blows the cooling or heating air into the environmental room in parallel, several flow dividers parallel to the wind flow divide the entire horizontal wind flow into multiple downward longitudinal air flows, and then pass through the wind-dispersing porous plate. The temperature-controlling wind flow above flows out from the evenly distributed wind-dispersing holes and is evenly distributed in the environmental room, thereby avoiding the problem of uneven temperature distribution in the environmental room caused by the temperature-controlling wind flow forming a hollow circulation in the environmental room. The temperature-controlling wind flow forms a laminar flow evenly distributed in the environmental room, so that the temperature distribution in the environmental room is even, thereby improving the control accuracy of the important working condition of the environmental temperature and the stability of the system;

[0017] 2) The device of the present invention designs an oil-gas separation system at the exhaust end of the compressor under test, and adds an oil return pipeline between the oil separator and the process port side of the compressor. The refrigerant discharged after the compressor works passes through the oil separator, which can filter out the oil particles brought out of the compressor. After the test is completed, the lubricating oil can return to the compressor through the oil return valve, thereby improving the purity of the refrigerant in the circulation pipeline and the lubrication performance of the compressor operation;

[0018] 3) The oil-gas separation system of the device of the present invention operates at a certain oil separation temperature. The oil separator and valve components are placed in an insulated oil separation room. The temperature is detected and adjusted in conjunction with the temperature control system, which greatly improves the efficiency of oil-gas separation. At the same time, the safety and reliability of the oil separation process is ensured by the over-temperature detection probe;

[0019] 4) The expansion valve of the calorimeter of the device of the present invention is located at the top of the calorimeter, and the evaporation coil is distributed from top to bottom in the calorimeter. When the low-temperature refrigerant flows through the evaporation coil and exchanges heat, it is not easy to accumulate oil impurities in the coil. The flow channel optimization of this method can effectively reduce the problem of oil accumulation in the evaporation circuit;

[0020] 5) The calorimeter in the device of the present invention uses direct current heating as its internal heating method. Compared with the previously used alternating current heating, direct current heating has the advantages of more stable output power, more accurate temperature control, and more precise electric energy accumulation;

[0021] 6) The measurement and control system in the device of the present invention controls the working conditions such as evaporation temperature, condensation temperature, subcooling temperature, ambient temperature, suction temperature and oil temperature. Sensors with different measuring ranges and accuracies are installed at various measuring points according to different measurement requirements. Through the mutual cooperation of the refrigeration unit and the heating device, a wide working condition test of the compressor can be realized, and continuous multi-working condition point testing can be realized, and the maximum number of working condition points can reach 128;

[0022] 7) The measurement and control system of the device of the present invention has a variety of refrigerant selections required for the compressor refrigeration capacity test. By adjusting the corresponding control parameters according to the different characteristics of different refrigerants, the test device can be adapted to the refrigeration system test of various working fluids and realize the multi-refrigerant testing function. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the appearance of the device of the present invention;

[0024] Figure 2 It is a schematic diagram of the refrigeration system principle of the device of the present invention;

[0025] Figure 3 It is a schematic diagram of the environmental wind flow circulation;

[0026] Figure 4 is a diagram of the internal structure of the calorimeter of the device of the present invention;

[0027] Figure 5 It is the principle diagram of the oil separation system of the device of the present invention;

[0028] Figure 6 It is the operation flow chart of the oil separation system of the device of the present invention;

[0029] Figure 7 It is a hardware block diagram of the measurement and control system of the device of the present invention;

[0030] Figure 8 It is a functional diagram of the measurement and control software of the device of the present invention;

[0031] Fig. 9 It is a flow chart of the test software of the device of the present invention;

[0032] The figure includes: 1-indicator light, 2-pressure gauge, 3-display screen, 4-system room, 5-observation window, 6-control mainboard, 7-electrical cabinet, 8-unit cabinet, 9-tested compressor, 10-return oil valve, 11-recovery valve, 12-oil separator, 13-exhaust valve, 14-balancing valve, 15-vacuum valve, 16-liquid filling valve, 17-intake valve, 18-condenser, 19-filter 1, 20-gas-controlled expansion valve 1, 21-visual Mirror liquid storage tank, 22-flow meter, 23-subcooler, 24-gas-controlled expansion valve 2, 25-gas-controlled expansion valve 3, 26-calorimeter, 27-gas-controlled expansion valve 4, 28-fan, 29-condenser, 30-recovery system, 31-condensing unit, 32-subcooling unit, 33-environmental unit, 34-recovery outlet valve, 35-filter 2, 36-filter 3, 37-filter 4, 38-porous plate, 39-layered windshield Plate, 40-heating tube 1, 41-heating tube 2, 42-heating tube 3, 43-heating tube 4, 44-heating tube 5 (heater), 45-suction pressure, 46-exhaust pressure, 47-oil temperature, 48-suction temperature, 49-exhaust temperature, 50-condensation outlet temperature, 51-subcooling temperature, 52-calorimeter tank wall temperature, 53-calorimeter internal temperature, 54-exhaust temperature, 55-exhaust pressure, 56-environment Temperature, 57-heat exchange copper coil (evaporator), 58-installation column, 59-insulation board, 60-calorimeter liquid level sight glass, 61-insulation layer, 62-heating medium, 63-manual valve one, 64-manual valve two, 65-manual valve three, 66-oil separation chamber, 67-oil separation environmental box, 68-refrigeration cycle fan, 69-over-temperature protection probe, 70-industrial computer, 71-inner cylinder, 72-outer shell, 73-return air pipe, 74-liquid inlet pipe. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims. Further, in order to enable the public to have a better understanding of the present invention, some specific details are described in detail in the following detailed description of the present invention. For those skilled in the art, the present invention can be fully understood without the description of these details. The present invention is further described below in conjunction with the drawings of the specification, but the protection scope of the present invention is not limited thereto:

[0035] The schematic diagram of the appearance of the high-precision measuring device for the refrigeration capacity of a refrigeration compressor of this embodiment is as follows: Figure 1As shown, the device is an integrated design, including a system room, a unit room and an electrical room, etc. The refrigeration system under test is in the system room 4. The working condition of the system can be observed in real time through the observation window 5. Three sets of refrigeration units and recovery units are installed in the unit cabinet 8 below the system room. The pressure gauge 2 on the upper right of the device can display the pressure value in the system. Various status indicator lights 1, display 3, electrical parameter instruments, emergency buttons, etc. are set on the upper left. The electrical cabinet 7 of the device is located at the rear left, which is composed of a variable frequency power supply, a DC power supply, an industrial computer 6, secondary instruments, electrical control circuits and data acquisition modules, etc., as an actuator for full automatic control and detection.

[0036] The schematic diagram of the principle of the high-precision compressor cooling capacity measurement device of this embodiment is as follows Figure 2 As shown, the exhaust end of the tested compressor 9 is equipped with an oil separator 12, which filters the oil in the refrigerant discharged from the tested compressor 9 and recovers it to the tested compressor 9 through the oil return valve 10. When replacing a new tested compressor, close the suction valve 17 and the exhaust valve 13, open the vacuum valve 15 to evacuate the test pipeline, if the refrigerant is insufficient, open the liquid adding valve 16 to add refrigerant to the system, and at the same time open the balance valve 14 to balance the pressure at both ends of the tested compressor. If the pressure in the pipeline is too high, open the recovery valve 11 to release part of the refrigerant into the recovery system 30, and discharge the system through the recovery outlet valve 34. The condenser 18 and the subcooler 23 are cooled by independent condensing refrigeration units 31 and subcooling refrigeration units 32, and the temperature is accurately controlled by the PID control of the heating pipe 2 41 and the heating pipe 3 42 in the tank. Observe the sight glass reservoir 21. If there are bubbles in the liquid mirror, it can be known that the refrigerant in the system is insufficient and refrigerant needs to be added. The flow meter 22 is used to measure the mass flow of the refrigerant in the test system, and then the theoretical refrigeration capacity is calculated by the calculation software. The test environment temperature control system is composed of an environment refrigeration unit 33, a gas-controlled expansion valve 25, an evaporator 29, a heating pipe 43, a circulating fan 28, etc.

[0037] The schematic diagram of the environmental temperature control airflow circulation of the environmental chamber of the high-precision compressor refrigeration capacity measurement device of this embodiment is as follows Figure 3As shown, the lateral wind flow blown out by the fan passes through two wind shields, first passes through the diverter wind shield 39 with a sparser distribution of vents, and then passes through the diverter wind shield 39 with a denser distribution of vents. The density of the wind flow changes from dense to sparse after passing through the two wind shields, and the lateral wind flow becomes a downward longitudinal wind flow, and is more uniform in lateral distribution. A venting porous plate 38 is installed above and below the environmental chamber. After the wind flow passes through the venting porous plate, a temperature-controlled airflow that is uniformly distributed in space is formed. At the same time, the venting porous plate also separates two upper and lower areas in the environmental chamber as a circulating air duct. The uniform temperature laminar flow enters the environmental chamber from top to bottom through the venting porous plate, and then flows out from the lower venting porous plate, enters the temperature-controlled room through the reflux channel, and returns to the fan inlet connected to the top after temperature control, completing the air flow cycle. This improvement in the structure of the environmental chamber allows the single hollow circulation originally formed in the environmental chamber to become a uniform and dense downward wind flow, ensuring that the temperature in the environmental chamber is uniformly distributed while also ensuring the stability of the internal wind circulation.

[0038] The internal structure of the calorimeter 26 of the compressor refrigeration capacity high-precision measurement device of this embodiment is as follows Figure 4 As shown, the calorimeter is composed of an evaporator 57, a gas-controlled expansion valve 27, an insulation layer plate 61, a heater 44, a second refrigerant 62, a calorimeter liquid level sight glass 59, a mounting column 58, an insulation plate 59, an inner tube 71, an outer shell 72, a return air pipe 73 and a liquid inlet pipe 74. The calorimeter tank is fixed in the device through the mounting column 58 above, and the mounting column is connected to the insulation plate 59, and the insulation plate is used to isolate the heat transfer; the outside and the pipeline interface are sealed with corresponding insulation materials. After entering the interior of the calorimeter, the refrigerant passes through the gas-controlled expansion valve 27, which adopts a gas-controlled thermal expansion valve, and the electric control and precise adjustment of the expansion valve are realized through an electric-gas conversion device. Then the refrigerant flows from top to bottom through the evaporator 57, and leaves the calorimeter after sufficient heat exchange. When the system refrigerant flows through the curved evaporator coil, it is easy to leave residual oil accumulation in the coil. The above-mentioned way of the refrigerant leaving the calorimeter from top to bottom can effectively prevent oil from being stored in the evaporation circuit. The body of the calorimeter tank serves to isolate the heat exchange between the inside and outside. The shell is composed of an inner tube 71, a heat preservation plate 61 and an outer shell 72. Fill with the second heat medium R142b, observe the calorimeter liquid level indicator 59, if the liquid level is at the half position of the mirror, it means that the amount of heating medium is appropriate. The heater 44 in the tank is connected to the DC power supply and the electric energy accumulation meter. The heating adjustment in the calorimeter tank is achieved by directly controlling the output voltage of the DC power supply, so that the electric energy accumulation is more accurate. The wall of the calorimeter tank is provided with a temperature sensor, which serves as an over-temperature protection. The pressure in the tank is connected to the overpressure protection switch to prevent overpressure.

[0039] The principle diagram of the oil separation system of the high-precision compressor refrigeration capacity measuring device of this embodiment is as follows: Figure 5As shown, the oil separation system includes an oil separation environment box 67, an oil separator 12, an air circulation device 68, a switching hand valve 1 63, a switching hand valve 2 64, a switching hand valve 3 65, and an electric heating device. The oil separation system environment box is wrapped with an insulation layer 61 to reduce the impact of the external environment on the temperature in the oil separation room. The oil separation system operation flow chart is shown in FIG. Figure 6 As shown, three hand valves are installed in the oil-gas separation system, namely hand valve 1 63, hand valve 2 64 and hand valve 3 65. The hand valves are switched to select whether to use the oil-gas separation function. If the oil-gas separation function is not used, the hand valves 2 and 3 are closed, and the hand valve 1 is opened so that the compressor does not pass through the oil separator after exhaust; when the oil-gas separation function is used, the hand valve 1 is closed, and the hand valves 2 and 3 are opened. If the oil-gas separation function is selected, the oil will be automatically returned during the test process and after each test, and the refrigeration oil separated in the oil separator will be injected back into the compressor. The switch of the oil return valve 10 is automatically controlled by the computer. The refrigeration circulation fan 68 installed in the oil separation chamber is connected to the corresponding refrigeration unit to stabilize the temperature of the oil separation chamber within a certain range. In order to more accurately control the temperature of the oil separation chamber, an electric heating pipe is added therein, and the temperature in the oil separation environment box is stabilized within a set range by controlling the power of the electric heating pipe.

[0040] The control system framework diagram of the high-precision compressor cooling capacity measurement device of this embodiment is as follows: Figure 7As shown, the industrial computer 70 is the core of the entire control system, and it has four standard interfaces. COM1 is connected to a DC resistance tester to measure the cold and hot resistance values ​​of the compressor motor winding to calculate the winding temperature rise after the compressor test is completed; COM2 and COM3 interfaces are used to connect the electric energy accumulation meter and the electric parameter meter, and are used for the communication of the electric parameter meter to obtain the operating power, current, power factor, calorimeter heating electric energy, three-phase output electric parameters of the variable frequency drive and flow meter flow of the tested compressor; COM4 is used for the communication of the flow meter 14. The USB interface and PS2 interface on the industrial computer are used to connect the mouse and keyboard respectively, and the VGA interface is connected to the industrial panel embedded display 64. The analog input interface card is used to measure analog signals such as external system temperature, system pressure, unit current, system vacuum and gas concentration; the high-speed data acquisition card is used to sample the compressor bus current and calculate the compressor speed and measure the compressor suction and exhaust pulsation; the expansion input and output interface card is used to detect the limit signal of external mechanical movement, pressure and temperature alarm signal and other input signals, and its output function is used to realize the control of the external heating system, refrigeration system, system pneumatic valve and other actuators; two-channel bus interface card, one channel and the variable frequency compressor speed adjustment pulse table form a master-slave bus network, which is used to send the frequency signal value corresponding to the variable frequency compressor speed to the pulse table; the other channel connects the thermocouple module and the analog output module, the thermocouple module is used to collect and process the compressor shell temperature, compressor exhaust temperature, calorimeter outer wall temperature, subcooler outer wall temperature, condenser outer wall temperature, subcooler internal temperature and condenser temperature, etc., and the analog output module is used to heat and control these temperatures.

[0041] The functional block diagram of the measurement and control software of the high-precision measurement device for the refrigeration capacity of the refrigeration compressor of this embodiment is as follows: Figure 8As shown, it includes functions such as parameter setting, data visualization, system control, report saving and safety alarm. Its parameter setting includes operating parameter setting, operating condition setting, system working fluid setting and test mode setting. The operating condition setting includes condensing temperature, evaporation temperature, subcooling temperature, suction temperature and ambient temperature; the system working fluid setting has test modes for various working fluids such as R600a, R290a, R134a, R1234yf, etc.; the test mode is divided into single working point test and continuous multi-working point test (maximum working point number 128). The data visualization includes real-time data visualization (digital and graphical), visualization of test status and visualization of diagnostic information. The system control is divided into manual operation and intelligent control, and its automatic control is divided into working condition control and process control, among which intelligent control is the intelligent control of all working conditions and the whole test process such as suction pressure 45, suction temperature 48, exhaust pressure 46, exhaust temperature 49, condensation outlet temperature 50, subcooling temperature 51, condenser outlet pressure 55 and condenser outlet temperature 54. The safety alarm includes gas leak detection and alarm, overpressure protection, overtemperature protection, gas source underpressure alarm and emergency stop button, etc. The gas leak alarm uses a combustible gas infrared sensor to detect the gas concentration in the test room, which is expressed as a percentage of the lower explosion limit and displayed in the measurement and control software. When the solubility reaches 10% of the lower explosion limit, a prompt warning signal will be generated in the software; when the concentration reaches 20% of the lower explosion limit, all power supplies in the test bench except the alarm power supply will be disconnected, inert gas nitrogen will be filled into the test room, and the leaked gas will be discharged to the outside through the exhaust fan to prevent the combustible gas concentration from exceeding the lower explosion limit and causing an explosion risk. At the same time, an audible and visual alarm signal will be generated; the overpressure protection That is, the pressure at the following positions is monitored and overpressure protection is implemented: exhaust overpressure alarm of the tested compressor, overpressure alarm in the calorimeter / condenser / subcooler, overpressure alarm in the environment / subcooler / condensing refrigeration unit, etc.; the over-temperature protection includes: ambient temperature over-temperature protection, oil separation room over-temperature protection, calorimeter over-temperature protection, subcooler over-temperature alarm and condenser over-temperature alarm; the gas source under-pressure alarm is that when the input gas source is lower than the set value, the power supply of the equipment will be automatically cut off and the gas source under-pressure will be prompted; an emergency stop button is set in the equipment. After pressing the emergency stop button, all power supplies in the equipment except the gas alarm power supply will be cut off.

[0042] The system operation flow of the high-precision measuring device for the refrigeration capacity of a refrigeration compressor of this embodiment is as follows: Fig. 9 The specific steps are as follows:

[0043] (1) Turn on the gas source and power supply, install the compressor to be tested into the test system, and ensure that the suction and exhaust ends are connected correctly.

[0044] (2) Set parameters, enter the parameter setting interface, set test condition parameters, system working fluid, operating parameters and test mode, etc.

[0045] (3) After selecting manual control, open the balancing valve, then evacuate the system under test, ensure that the suction valve and exhaust valve are closed, open the vacuum valve of the vacuum pump, and close the vacuum valve and vacuum pump after the vacuum requirement is met.

[0046] (4) Perform the liquid adding operation, open the liquid adding valve, and add appropriate refrigerant.

[0047] (5) Start the press: Observe whether the press starts normally. If not, shut down the press and the start-up fails. If normal, proceed to the next step.

[0048] (6) Close the balancing valve, open the exhaust valve and the suction valve, click on the intelligent control, and then enter the intelligent control mode of the test;

[0049] The intelligent control process is as follows:

[0050] 6.1) Sensors distributed at various working condition test points feed back temperature, pressure, speed and other conditions to the control center in real time;

[0051] 6.2) According to the feedback, the control center uses PID control, robust control, feedforward control, expert system, intelligent control and other control methods to perform high-precision control on all working conditions such as pressure, temperature and opening of related valves of the refrigeration system;

[0052] 6.3) The test system measures and calculates all data such as cooling capacity and electrical parameters in real time with high precision through the measured parameters such as temperature, pressure, electrical power and flow rate;

[0053] (7) After four consecutive data are within the error range, the test is completed.

[0054] (8) All test data are saved in real time, test reports are output, and the system automatically turns off the power.

Claims

1. A high-precision compressor refrigeration capacity test device with wide working conditions and multiple refrigerants, characterized in that: Including measurement and control system, test software system and refrigeration system; The measurement and control system cooperates with the measurement and control software system to measure, judge, control, establish database, process data and conduct human-computer interaction on the refrigeration system; The test software system is used to realize parameter setting, data visualization, system control, safety alarm and report saving functions; The refrigeration system includes the main test system and the test environment system; The main test system includes the tested compressor, oil separation system, condenser, subcooler, flow meter, expansion valve, and calorimeter; An oil separation system is set at the exhaust end of the compressor under test to separate the lubricating oil discharged from the compressor and return it to the compressor; After the refrigerant passes through the tested compressor to do work, it forms high-temperature and high-pressure gas, which passes through the condenser and subcooler in turn to become high-pressure and subcooled refrigerant liquid; the high-pressure and subcooled refrigerant liquid passes through the expansion valve to become low-temperature and low-pressure liquid and enters the calorimeter, and after absorbing heat and evaporating, it becomes superheated and low-pressure gas and enters the compressor; the heat absorbed in the calorimeter is measured to reflect the cooling capacity of the compressor, and compared with the cooling capacity measured by the flow meter; The test environment system provides the test environment for the main test system, including cooling system, heater, and air circulation system to control the ambient temperature within the range specified by the working conditions.

2. A high-precision compressor refrigeration capacity test device with wide operating conditions and multiple refrigerants according to claim 1, characterized in that: The oil separation system includes an oil separation environment box, an oil separator, an air circulation device, a switching valve and an electric heating device; the oil separator is arranged in the oil separation environment box, and an oil return pipeline and an oil return valve are arranged between the oil separator and the process port side of the compressor under test. During the test and after the test, the separated lubricating oil flows back into the compressor through the oil return valve; by switching the valve, it is selected whether to use the oil separation function; the oil separation environment box is provided with an air circulation device and an electric heating device, which can stabilize the temperature in the oil separation environment box within the set range.

3. The high-precision compressor refrigeration capacity test device with wide working conditions and multiple refrigerants according to claim 1 is characterized in that: The condenser and subcooler are both heat exchangers filled with heat exchange medium, which are cooled by the condensing unit and the subcooling unit respectively, and the heating controller realizes accurate and stable control of the condensing temperature and the subcooling temperature; a filter, a sight glass liquid reservoir and a flow meter are sequentially arranged on the connecting pipeline between the condenser and the subcooler; the liquid level of the sight glass liquid reservoir is used to judge whether refrigerant needs to be added, and the flow meter is used to measure the mass flow rate of the refrigerant to obtain the auxiliary refrigeration capacity.

4. A high-precision compressor refrigeration capacity test device with wide operating conditions and multiple refrigerants according to claim 1, characterized in that: The test environment system comprises an environment chamber, an environment refrigeration unit, a gas-controlled expansion valve, an evaporator, a heater and a circulation fan; the circulation fan is installed at the air outlet position of the environment chamber, and two longitudinal diverter plates are arranged on the upper wall of the environment chamber at positions corresponding to the air outlet, and the vents on the diverter plate close to the air outlet are densely distributed while the vents on the diverter plate far from the air outlet are sparsely distributed; the density of the airflow changes from dense to sparse after passing through the two wind shields, and the lateral airflow changes to downward longitudinal airflow, and the lateral distribution is more uniform; A porous air-dispersing plate is installed horizontally below the diverter plate to separate a top air outlet duct. The porous air-dispersing plate is evenly arranged with air holes of the same size. The wind flows through the porous air-dispersing plate to form an environmental temperature field with uniform and stable wind speed. A porous air-dispersing plate is arranged below the environmental chamber to separate a bottom return air duct. Uniform temperature laminar flow enters the environmental chamber from top to bottom, flows out from the bottom, enters the controlled temperature room through the return channel, and returns to the fan inlet connected to the top after temperature control to complete the air flow circulation.

5. The high-precision compressor refrigeration capacity test device with wide working conditions and multiple refrigerants according to claim 1 is characterized in that: The calorimeter comprises an inner cylinder, an outer cylinder, an evaporating tube, a heater, a liquid indicator mirror, a liquid inlet pipe, an air return pipe, a heat preservation board, an insulation board, and a mounting column; an expansion valve is placed in the calorimeter, and a heat preservation layer is filled between the outer cylinder and the inner cylinder; the insulation board is placed above and below the inner cylinder, the mounting column is connected to the insulation board, and the insulation board is used to isolate heat transfer; the inner cylinder is filled with a second refrigerant, and the liquid indicator mirror is used to observe the liquid level of the second refrigerant; the heater is arranged in the inner cylinder, and is used to control the temperature of the second refrigerant, and the heater is connected to a DC power supply and an electric energy accumulation device; The refrigerant enters the calorimeter from the liquid inlet pipe, passes through the expansion valve first, then flows from top to bottom through the evaporation pipeline, and returns to the compressor through the return pipe after sufficient heat exchange; temperature sensors are installed inside and outside the inner cylinder of the calorimeter to play the role of temperature control and over-temperature protection. The calorimeter is equipped with an overpressure protection switch to prevent overpressure.

6. The high-precision compressor refrigeration capacity test device with wide working conditions and multiple refrigerants according to claim 1 is characterized in that: It also includes a tested compressor replacement system, which includes an intake valve, an exhaust valve, a liquid adding valve, a vacuum valve, a balancing valve, a recovery valve, a recovery system, a recovery outlet valve, a liquid adding pipeline, and a recovery pipeline; an intake valve is provided on the pipeline between the intake port of the tested compressor and the calorimeter, and an exhaust valve is provided between the exhaust port and the condenser; the liquid adding valve and the vacuum valve are arranged on the intake side pipeline, the recovery valve is arranged on the exhaust side pipeline, the balancing valve connects the intake side and the exhaust side, and the recovery valve is connected to the recovery system; before replacing the new tested compressor, close the intake valve and the exhaust valve, recover the refrigerant at both ends of the compressor, then replace the new compressor, open the balancing valve and the vacuum valve to evacuate, and enter the test after the vacuum is reached; if the refrigerant is insufficient, open the liquid adding valve to add refrigerant to the refrigeration system.

7. The high-precision compressor refrigeration capacity test device with wide operating conditions and multiple refrigerants according to claim 1 is characterized in that: The measurement and control system adopts an industrial computer + industrial board mode, and the four serial interfaces of the industrial computer are used to measure the cold and hot resistance values ​​of the compressor motor windings, operating power, current, power factor, calorimeter heating power, variable frequency drive three-phase output electrical parameters and flow meter flow; the analog input interface is used to measure the external system temperature, system pressure, unit current, system vacuum and gas concentration analog signals; the high-speed data acquisition card is used to sample the compressor bus current and calculate the compressor speed and measure the compressor suction and exhaust pulsation; the input and output interface card is used to detect the limit signal, pressure and temperature alarm signal and other input signals of the external mechanical movement, and its output function is used to realize the control of the external heating system, refrigeration system, system pneumatic valves and other actuators; two-channel serial interface card, one channel and the variable frequency compressor speed adjustment pulse table form a master-slave bus network, which is used to send the frequency signal value corresponding to the variable frequency compressor speed to the pulse table; the other channel is connected to the temperature measurement module.

8. The high-precision compressor refrigeration capacity test device with wide working conditions and multiple refrigerants according to claim 1 is characterized in that: The test software system includes a parameter setting unit, a data visualization unit, a system control unit, a safety alarm unit, and a report storage unit; The parameter setting unit includes operating parameter setting, operating condition setting, system working fluid setting and test mode setting. The operating conditions include condensing temperature 35-80°C, evaporating temperature -60-20°C, supercooling temperature 25-65°C, suction temperature 20-50°C, speed 50-6500rpm, ambient temperature 20-50°C and oil separation chamber temperature 40-75°C; the system working fluid includes test modes of multiple working fluids such as R600a, R290a, R134a and R1234yf; the test mode is divided into single working point test and continuous multi-working point test, with a maximum number of working points of 128; The data visualization unit includes real-time data visualization, test status visualization, and diagnostic information visualization; The system control unit is divided into manual operation and intelligent control, among which intelligent control is the intelligent control of all working conditions and the entire test process; The safety alarm unit includes gas leak detection and alarm, pressure overpressure protection, temperature overtemperature protection and gas source underpressure alarm; the gas leak alarm uses a combustible gas infrared sensor to detect the gas concentration in the test room, and automatically performs graded protection according to the concentration; the overpressure protection includes: exhaust overpressure alarm of the tested compressor, overpressure alarm in the calorimeter / condenser / subcooler, and overpressure alarm of the environment / subcooling / condensing refrigeration unit; the overtemperature protection includes: ambient temperature overtemperature protection, oil separation room overtemperature protection, calorimeter overtemperature protection, subcooler overtemperature alarm and condenser overtemperature alarm; the gas source underpressure alarm is that when the input gas source is lower than the set value, the power supply of the equipment will be automatically cut off and the gas source underpressure will be prompted; an emergency stop button is also provided. After pressing the emergency stop button, other power supplies in the equipment except the gas alarm power supply are cut off.

9. A high-precision compressor refrigeration capacity test method for a wide range of working conditions and multiple refrigerants, characterized in that: The steps include: Step 1) Turn on the gas source and power supply, install the compressor to be tested into the system, and ensure that the suction end and the exhaust end are connected correctly; Step 2) Set parameters, enter the parameter setting interface, set test condition parameters, system working fluid, operating parameters and test mode; Step 3) After selecting manual control, open the balance valve, then evacuate the system under test, ensure that the suction valve and exhaust valve are closed, open the vacuum pump and vacuum valve, and close the vacuum valve and vacuum pump after the vacuum requirement is reached; Step 4) perform liquid adding operation, open the liquid adding valve, and add appropriate refrigerant; Step 5) Start the compressor under test and observe whether the compressor under test starts normally. If not, shut down the compressor and the startup fails. If normal, proceed to the next step; Step 6) Close the balancing valve, open the exhaust valve and the suction valve, click on the smart control, and then enter the smart control mode of the test; The intelligent control process is as follows: Through PID control, robust control, feedforward control, expert system and intelligent control, the pressure, temperature and opening conditions of the refrigeration system are controlled with high precision, and the refrigeration capacity and electrical parameter data are measured and calculated with high precision in real time; Step 7) After four consecutive data are within the error range, the working condition test is completed; Step 8) All sampled test data is saved in real time, the test report is output, and the system automatically turns off the power.

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