On-line evaluation device and method for performance of compressor by refrigerant / lubricating oil

Abstract

The invention discloses an on-line evaluation device and method for the performance of a compressor by a refrigerant / lubricating oil. According to the invention, the mixing ratio of the lubricating oil and the refrigerant can be accurately controlled, fluid thermophysical parameters such as intersolubility, liquid phase density and viscosity of the lubricating oil and the refrigerant can be synchronously obtained on line, and various actual operation conditions of the compressor can be simulated by flexibly adjusting temperature, pressure, flow and load conditions; and the temperature, pressure, flow, power and other key operation parameters of the compressor under each simulated working condition are monitored in real time, so that the influence of the interaction of the lubricating oil and the refrigerant on the operation efficiency, stability and service life of the compressor is comprehensively and accurately evaluated, and a scientific basis and technical guidance are provided for performance optimization of the compressor.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and in particular to an online evaluation device and method for evaluating the performance of a compressor using a refrigerant / lubricating oil. Background Art

[0002] Under the dual pressures of energy conservation and environmental protection, the development of environmentally friendly and energy-efficient environmentally friendly refrigerants with low greenhouse effect has become a key strategic issue that needs to be urgently addressed in my country's automotive air-conditioning industry. In addition to the refrigerant itself having excellent thermal performance, environmental protection, safety and economy, the miscibility of lubricants and refrigerants is also an important consideration. The miscibility of lubricants and refrigerants directly affects the oil return capacity of the compressor. On the premise of ensuring miscibility, the solubility of refrigerants in lubricants will change the working viscosity, anti-friction performance and friction reduction performance of the lubricant, which in turn has an important impact on the operating efficiency and life of the compressor. Therefore, the fluid physical properties of refrigerants and lubricants are key parameters for evaluating the performance of refrigeration systems and unit design.

[0003] The interaction between refrigerant and lubricant is very complex. There is still a certain gap in the research on the impact of lubricant on the operating performance of compressors. Currently, there is a lack of a comprehensive and accurate online evaluation device and method. Summary of the invention

[0004] In view of this, the present invention provides an online evaluation device and method for refrigerant / lubricant on compressor performance, which can accurately control the mixing ratio of lubricant and refrigerant, synchronously obtain the fluid thermal physical parameters such as the miscibility, liquid phase density and viscosity of lubricant and refrigerant online, and monitor the key operating parameters of the compressor such as temperature, pressure, flow and power in real time, so as to comprehensively and accurately evaluate the impact of the interaction between lubricant and refrigerant on compressor performance. The method of the present invention makes up for the shortcomings of the prior art and provides a scientific basis and technical guidance for optimizing the ratio of lubricant and refrigerant and improving compressor performance.

[0005] The present invention provides an online evaluation device and method for refrigerant / lubricant oil to compressor performance, which mainly includes a compressor 1, an oil separator 2, an oil cooler 3, a water tank 4, a filter 5, an electronic three-way valve 6, an oil storage tank 7, an air storage tank 8, 25, an electronic proportional valve 9, a capillary viscometer 11, a constant temperature bath 12, a temperature controller 14, 32, a mass flow meter 15, 27, a liquid phase gear pump 16, a pressure sensor 17, a platinum resistor 18, a condenser 23, a cooler 24, a back pressure valve 26, an expansion valve 28, an electric heating calorimeter 29, a flow regulating valve 30, a voltmeter, an ammeter and multiple valves.

[0006] Among them, the compressor 1 is mainly responsible for compressing gas and driving the refrigeration cycle. This invention mainly tests the effects of the lubricating oil / refrigerant mixed solution on the operating efficiency, stability, and service life of the compressor.

[0007] The oil separator 2 is placed at the outlet of the compressor 1 and is used to separate the lubricating oil from the refrigerant in the gas discharged from the compressor 1 and send them into the oil return pipeline and the gas return pipeline respectively, ensuring the recycling of the lubricating oil.

[0008] The compressor 1 and the oil separator 2 are placed in a constant temperature box 31. The constant temperature box 31 adjusts the temperature through a temperature controller 32 to simulate the ambient temperature when the compressor 1 operates, which can effectively control the experimental environment and avoid gas leakage to ensure that the experiment is carried out under stable temperature control conditions.

[0009] The oil cooler 3, the condenser 23, the cooler 24, and the water tank 4 form a cooling unit, which is used to reduce the temperature of the lubricating oil and the refrigerant at the outlet of the compressor 1 to prevent the performance of the compressor 1 from decreasing or being damaged due to high-temperature operation. Specifically, the oil cooler 3 is placed at the oil circuit outlet of the oil separator 2 and reduces the temperature of the lubricating oil at the outlet of the compressor 1 through heat exchange with the cooling water provided by the water tank 4, ensuring that the lubricating oil flows within a reasonable temperature range, preventing it from failing in a high-temperature environment, and ensuring the long-term stable operation of the evaluation device. The condenser 23 is placed at the gas circuit outlet of the oil separator 2 and reduces the temperature of the refrigerant at the outlet of the compressor 1 through heat exchange with the cooling water provided by the water tank 4, ensuring that the refrigerant in the gas return pipeline does not overheat. The cooler 24 further reduces the temperature of the liquid refrigerant and stabilizes the system pressure.

[0010] The compressor 1, the oil separator 2, the oil cooler 3, the water tank 4, the filter 5, the electronic three-way valve 6, the oil storage tank 7, the gas storage tank 8, the electronic proportional valve 9, the balance kettle 10, the capillary viscometer 11, the valve 13, the temperature controller 14, the mass flowmeter 15, and the liquid-phase gear pump 16 are connected by pipelines to form an oil return pipeline.

[0011] Among them, the filter 5 is placed at the outlet of the oil cooler 3 and is connected to the balance kettle 10 through the electronic three-way valve 6; the filter 5 effectively removes the possible solid impurities in the circulating lubricating oil, ensures the purity of the lubricating oil, and avoids abrasion or damage to the compressor 1 and other key components. The oil storage tank 7 is used to store and supply lubricating oil and is connected to the balance kettle 10 through the electronic three-way valve 6 to ensure sufficient lubricating oil supply during the long-term operation of the evaluation device. The electronic three-way valve 6 adjusts the lubricating oil output of the oil storage tank 7 according to the amount of circulating lubricating oil in the oil return pipeline, precisely controlling the amount of lubricating oil entering the balance kettle 10.

[0012] The gas storage tank I 8 is used to store and supply the refrigerant, and is connected to the balance kettle 10 through the electronic proportional valve 9. The electronic proportional valve 9 is used to accurately control the amount of refrigerant entering the balance kettle 10.

[0013] The electronic three-way valve 6 and the electronic proportional valve 9 cooperate to accurately control the mixing ratio of the lubricating oil and the refrigerant in the balance kettle 10, ensuring that the refrigerant / lubricating oil mixed solution under a specific ratio is input into the compressor 1.

[0014] The balance kettle 10 is used to prepare a uniform mixed solution of lubricating oil and refrigerant; the balance kettle 10 is placed in the circulating bath 21, and the temperature is adjusted and maintained by the constant temperature bath 12 to ensure that the balance kettle 10 always operates in a constant temperature environment, ensuring that the lubricating oil and the refrigerant are fully dissolved in accordance with the set ratio under the constant temperature environment. The platinum resistance 18 is used to monitor the temperature in the circulating bath 21 in real time, and the pressure sensor 17 is used to monitor the pressure change in the balance kettle 10 in real time.

[0015] An observation window is provided on the balance kettle 10, and the camera 22 is equipped to monitor the mixing process of the lubricating oil and the refrigerant in real time, while avoiding the leakage of the lubricating oil and external interference; record parameters such as the appearance and flow condition of the mixed solution, which can be used as a reference for the service life of the compressor 1.

[0016] The lubricating oil / refrigerant mixed solution mixed evenly by the balance kettle 10 passes through the capillary viscometer 11, valve I 13, temperature controller I 14, and mass flowmeter I 15 in sequence, and is pumped into the compressor 1 by the liquid-phase gear pump 16. This mixed solution is used to lubricate the moving parts in the compressor, reduce friction loss, and provide a sealing effect in the compressor. In addition, the mixed solution can take away part of the heat generated during the compression process, assist in cooling the compressor, thereby improving its operating efficiency and service life. Among them, the capillary viscometer 11 is used to measure the viscosity of the mixed solution at the outlet of the balance kettle 10; by measuring the pressure change at the inlet and outlet of the capillary viscometer 11 and combining with the Poiseuille formula, the dynamic viscosity of the mixed solution is calculated, so as to evaluate its flow performance. When selecting the pipe diameter of the capillary viscometer 11, the specifications should be reasonably determined according to the viscosity range and flow characteristics of the measured mixed solution. Referring to the experimental data, liquids with low viscosity (<100 mPa·s) are suitable for capillary pipe diameters of 0.25 - 1 mm; liquids with high viscosity (>100 mPa·s) are suitable for pipe diameters of 0.8 - 1.5 mm to reduce the flow resistance and improve the measurement accuracy. The valve I 13 is used to adjust the flow of the mixed solution. The temperature controller I 14 is used to control the temperature of the mixed solution at the outlet of the balance kettle 10 to ensure that the temperature meets the experimental requirements; the mass flowmeter I 15 is used to monitor the flow rate and density of the mixed solution in the oil return pipeline in real time. The liquid-phase gear pump 16 is used to provide a stable flow rate of the lubricating oil / refrigerant mixed solution, ensuring that the lubricating oil continuously circulates in the system pipeline and overcoming the pipeline pressure loss.

[0017] The balance kettle 10 is also connected to the recovery bottle 20 through valve II 19. The recovery bottle 20 is used to recover the waste lubricating oil and refrigerant in the balance kettle 10, ensuring the material cycle in the system and preventing pollution.

[0018] The compressor 1, oil separator 2, condenser 23, cooler 24, gas storage tank 25, back pressure valve 26, mass flowmeter 27, expansion valve 28, electric heating calorimeter 29, and flow regulating valve 30 are sequentially connected by pipelines to form a return air pipeline.

[0019] The high-temperature refrigerant separated by the oil separator 2 enters the gas storage tank II 25 after being cooled by the condenser 23 and cooler 24. The gas storage tank II 25 is used to store and supply the refrigerant in the return air pipeline. The refrigerant in the gas storage tank II 25 sequentially passes through the back pressure valve 26, mass flowmeter II 27, expansion valve 28, electric heating calorimeter 29, and flow regulating valve 30, and then enters the compressor 1. The refrigerant participates in the compression process as a working medium in the compressor, increasing the temperature and pressure to meet the system circulation requirements. At the same time, the refrigerant cooperates with the lubricating oil to cool the moving parts and maintain the stable operation of the compressor. Among them, the back pressure valve 26 is used to regulate the pressure change in the return air pipeline, preventing excessive or too low pressure from affecting the system operation and ensuring the safety of the system operation. The mass flowmeter II 27 is used to real-time monitor the mass flow and density of the refrigerant in the return air pipeline. The expansion valve 28 is used to throttle and reduce the pressure of the refrigerant before entering the calorimeter, controlling its flow and pressure to ensure that the refrigerant reaches the appropriate temperature and pressure state before entering the electric heating calorimeter 29. The electric heating calorimeter 29 completely evaporates the refrigerant liquid after the expansion valve 28 through electric heating, ensuring that the refrigerant is completely vaporized before entering the compressor 1, avoiding the influence of liquid existence on the efficiency and life of the compressor 1, and simultaneously measuring the pressure, temperature, and heat change of the return gas. The flow regulating valve 30 is used to precisely control the flow rate of the refrigerant in the return air pipeline to meet the experimental requirements under different working conditions.

[0020] Multiple temperature and pressure measurement points are set at key positions such as the inlet and outlet of the compressor 1 and the inlet and outlet of the balance kettle 10, and a voltmeter and an ammeter are installed at the inlet of the compressor. These measuring devices, together with the mass flowmeter 27, etc., form a compressor performance parameter detection system, which is used to real-time monitor the operating performance parameters of the compressor 1 after the mixed solution enters the compressor 1, including the inlet and outlet temperature and pressure, flow rate, and power, etc. The recorded parameters are transmitted and analyzed online through the data acquisition system, so as to comprehensively evaluate the operating performance of the compressor 1 and the system efficiency.

[0021] The present invention precisely controls the mixing ratio of lubricating oil and refrigerant through the electronic three-way valve 6 and the electronic proportional valve 9 (for example, the ratio of lubricating oil to refrigerant is controlled between 99.5:0.5 and 96:4), and simulates the operation process of the compressor under different working conditions by adjusting temperature, pressure, flow rate, and power load conditions. The device can online monitor key operating parameters, providing a reliable basis for evaluating the influence of the mixed solution on the compressor performance. Compared with the prior art, the present invention can precisely control the mixing ratio of the mixed solution, achieve dynamic parameter measurement, and simplify the heat exchange system. The device can comprehensively and accurately online evaluate the influence of the mixed solution on the operating performance of the compressor, making up for the deficiencies of the prior art, and having high practicability and accuracy.

[0022] The present invention also provides a method for evaluating the influence of a lubricating oil-refrigerant mixed solution on the operating performance of a compressor by using the above device, including the following steps:

[0023] Step 1, precisely control the ratio of lubricating oil and refrigerant injected into the equilibrium kettle 10 through the electronic three-way valve 6 and the electronic proportional valve 9 (for example, the ratio of lubricating oil to refrigerant is controlled between 99.5:0.5 and 96:4). The equilibrium kettle 10 is placed in a circulating bath 21 whose temperature is controlled by a constant temperature bath 12, and is provided with an observation window, and a camera 22 can be used to record the solution mixing situation in real time. Under the set constant temperature environment, the refrigerant and lubricating oil are fully and evenly mixed in the equilibrium kettle 10 to form a target mixed solution.

[0024] Step 2, after step 1, use a mass flowmeter I15 to online monitor the mass flow rate and density of the mixed liquid in the pipeline.

[0025] Step 3, after step 2, obtain the pressure difference between the inlet and outlet through the pressure measurement points set at the inlet and outlet of the capillary tube, and calculate the viscosity of the mixed solution by using the Poiseuille formula to evaluate its flow performance. The specific calculation formula is as follows:

[0026]

[0027] where η is the hydrodynamic viscosity, ΔP is the pressure difference between the two ends of the capillary tube, d is the diameter of the capillary tube, L is the length of the capillary tube, and Q m is the mass flow rate, measured by the mass flowmeter I15.

[0028] Step 4, after step 3, input the target mixed solution into the compressor 1, and respectively transport it to the oil return pipeline or the suction pipeline through the oil separator 2. The liquid-phase gear pump 16 is used to maintain a stable lubricating oil flow rate to ensure the continuous flow of lubricating oil in the pipeline; use a temperature controller I14 to adjust the temperature of the mixed solution to ensure that it is stable within the set range.

[0029] Step 5: The compressor 1 and the oil separator 2 are placed in the constant temperature box 31, and the temperature inside the box is controlled by the temperature controller II 32 to simulate the actual operating environment.

[0030] Step 6: In the return gas pipeline, the mass flow rate and density of the refrigerant are measured in real time by the mass flowmeter II 27. The electric heating calorimeter 29 completely evaporates the liquid in the working medium after the expansion valve 28 by means of electric heating to ensure that the refrigerant is completely vaporized before flowing back into the compressor 1. At the same time, the pressure, temperature and heat change of the return gas are measured.

[0031] Step 7: After Step 6, the refrigerant with the target flow rate set by the flow regulating valve 30 is sent back to the compressor 1 for continued compression. The back pressure valve 26 is used to control the operating pressure of the system to ensure that it is maintained within a stable range.

[0032] Step 8: After Step 7, the temperature, pressure, flow rate of the gas at the inlet and outlet of the compressor 1 and the input power of the compressor 1 are monitored online through the compressor performance parameter detection system (including multiple temperature and pressure measurement points, mass flowmeter 27, ammeter and voltmeter, etc.) at the inlet and outlet of the compressor 1, and comprehensive operating parameter data are collected.

[0033] Step 9: By changing parameters such as the mixing ratio, temperature, pressure and flow rate of the lubricating oil and the refrigerant, the working conditions matching the actual operating conditions of the compressor 1 are simulated to ensure the representativeness and reliability of the test data.

[0034] Step 10: All data are transmitted to the data acquisition system for online analysis to evaluate the operating efficiency, stability and service life of the compressor under different mixing ratios of lubricating oil and refrigerant. The specific evaluation methods are as follows:

[0035] (1) Operating efficiency evaluation method: Calculate the refrigerating capacity Q and the isentropic efficiency η of the compressor through thermodynamic formulas s

[0036] The formula for calculating the refrigerating capacity is:

[0037] Q = Q m Δh

[0038] where Q m is the mass flow rate, measured by the mass flowmeter II 27; Δh is the enthalpy difference, obtained by looking up the table.

[0039] The formula for calculating the isentropic efficiency is:

[0040]

[0041] where h 1 is the enthalpy value at the suction end of the compressor; h 2 ′ is the enthalpy value at the discharge end after isentropic compression; h2 is the enthalpy value at the actual exhaust end. A high isentropic efficiency indicates less energy loss.

[0042] (2) Stability analysis method: All key parameters (temperature, pressure, power, flow rate) are monitored in real time, and the monitoring period and experimental duration are set to obtain stability data. The fluctuation amplitude is calculated by the following formula:

[0043]

[0044] where: σ is the standard deviation of parameter fluctuation; x i is the parameter value at the i-th sampling point; is the average value of the parameter. If the parameter fluctuation amplitude is large, it indicates poor system stability.

[0045] (3) Operating life assessment method: The compressor 1 is run for a long time, and performance parameters are periodically collected and key evaluation parameters (such as the isentropic efficiency η s ) are calculated. A curve of the key evaluation parameter changing with time is plotted, and an exponential decay model is used for fitting to obtain the decay coefficient α:

[0046] η s (t) = η s (0)·e -αt

[0047] where, η s (t) is the performance parameter value at time t; η s (0) is the initial performance parameter value; α is the decay coefficient, reflecting the rate of performance decline; t is the operating time.

[0048] Calculate the time required for the key evaluation parameter of the compressor to drop to the set threshold (such as η s dropping to 60 - 65% of the initial value). At the same time, lubricating oil samples in the compressor oil sump are regularly extracted to detect performance indicators such as viscosity, acid value, and impurity content. When the lubricating oil viscosity drops to 80 - 90% of the initial value or reaches other failure criteria, lubrication failure is judged. Finally, combined with performance decay data, lubricating oil deterioration trend, and mechanical performance indicators such as friction noise, the operating life of the compressor is comprehensively evaluated and more accurately predicted.

[0049] (4) According to the analysis results, evaluate the effects of lubricating oil and refrigerant on the performance of the compressor, optimize the ratio of lubricating oil and refrigerant, and propose a plan and suggestions to optimize the performance of the compressor.

[0050] In addition, to ensure the accuracy and reproducibility of the experimental results, 5 measurements are carried out for each temperature, pressure, and component experimental point.

[0051] Beneficial effects:

[0052] The present invention uses an electronic three-way valve 6 and an electronic proportional valve 9 to precisely adjust the mixing ratio of lubricating oil and refrigerant, and obtains the viscosity and density of the mixed solution through a capillary viscometer 11 and a mass flowmeter I15. By flexibly adjusting temperature, pressure, flow rate, and power load conditions, various actual operating conditions of the compressor are simulated; by real-time monitoring of the fluid thermal physical properties of the mixed solution (such as miscibility, viscosity, density), as well as parameters such as inlet and outlet temperature, pressure, flow rate, and power of the compressor under various simulated conditions, the impact of mixed solutions with different ratios on the operating efficiency, stability, and service life of the compressor is comprehensively and accurately evaluated, providing a scientific basis and technical guidance for the performance optimization of the compressor.

[0053] The present invention gradually optimizes the ratio of lubricating oil and refrigerant by precisely controlling the mixing ratio of the mixed solution and repeatedly evaluating the operating performance of the compressor system, and finds the optimal ratio to improve the overall performance of the compressor; secondly, the present invention fills the blank in the prior art regarding the evaluation of the impact of the ratio of lubricating oil and refrigerant on the operating performance of the compressor. Through real-time monitoring and data analysis, the optimal ratio of lubricating oil and refrigerant can be scientifically selected to improve the performance of the compressor system, which has high practicality and broad application prospects. Brief Description of the Drawings

[0054] Figure 1 It is a schematic diagram of an evaluation device for the impact of the lubricating oil-refrigerant mixed solution of the present invention on the operating performance of the compressor.

[0055] Among them, 1 - compressor, 2 - oil separator, 3 - oil cooler, 4 - water tank, 5 - filter, 6 - electronic three-way valve, 7 - oil storage tank, 8 - gas storage tank I, 9 - electronic proportional valve, 10 - equilibrium kettle, 11 - capillary viscometer, 12 - constant temperature bath, 13 - valve I, 14 - temperature controller I, 15 - mass flowmeter I, 16 - liquid-phase gear pump, 17 - pressure sensor, 18 - platinum resistance, 19 - valve II, 20 - recovery bottle, 21 - circulating bath, 22 - camera, 23 - condenser, 24 - cooler, 25 - gas storage tank II, 26 - back pressure valve, 27 - mass flowmeter II, 28 - expansion valve, 29 - electric heating calorimeter, 30 - flow regulating valve, 31 - constant temperature box, 32 - temperature controller II. Detailed Embodiment

[0056] The following combines the drawings and gives embodiments to describe the present invention in detail.

[0057] Build an evaluation device as shown in Figure 1 and conduct on-line evaluation of the compressor performance. The specific operation steps are as follows:

[0058] S1, Check the equipment connection

[0059] First, check whether all components are correctly connected as required. Ensure that the pipelines of equipment such as compressor 1, oil separator 2, oil cooler 3, balance kettle 10, oil storage tank 7, condenser 23, etc. are leak-free, the power connections are normal, and the equipment is in good condition. The inner diameter of the pipeline is generally set at 8 - 12 mm.

[0060] S2, Preparation of the mixed solution of lubricating oil and refrigerant

[0061] S2.1, Select CO as the refrigerant 2 , and select common ISO mineral oil / VG / POE / PVG as the lubricating oil. Use the electronic three-way valve 6 and the electronic proportional valve 9 to control the flow rates of the lubricating oil and the refrigerant, and accurately inject them into the balance kettle 10 according to the set mass ratio (such as 99.5:0.5, 99:1, 99:2, 99:3, and the refrigerant content cannot exceed 4%);

[0062] S2.2, Place the balance kettle 10 in the circulating bath 21, start the constant temperature bath 12, and set the ambient temperature in the range of -10 to 50 °C; then start the balance kettle 10 to allow the mixed solution to mix fully for more than 60 minutes at a constant temperature to ensure that the lubricating oil and the refrigerant are fully dissolved.

[0063] S3, Initial parameter setting and measurement of the mixed solution

[0064] S3.1 Start the liquid-phase gear pump 16, keep the valve of the oil return pipeline open, and set the temperature controller I14 in the range of 30 - 50 °C. Inject the prepared mixed solution into the compressor 1 and make it circulate stably in the oil return pipeline;

[0065] S3.2, The capillary viscometer 11 is used to measure the viscosity of the mixed solution. It is recommended to select a capillary diameter d of 0.5 - 1 mm when measuring the lubricating oil. The pressure measurement points set at the inlet and outlet of the capillary are used to obtain the pressure difference ΔP, and the Coriolis mass flowmeter 15 is used to measure the mass flow rate Q m and density ρ in the pipeline. Then, use the Poiseuille formula to calculate the viscosity η of the mixed solution and record the data in real time to evaluate its flow performance. The specific calculation formula is as follows:

[0066]

[0067] where η is the hydrodynamic viscosity, d is the capillary diameter, and L is the capillary length.

[0068] S3.3, Check the sealing performance and operating status of the oil return pipeline; record in real time the temperature, pressure, flow rate and other parameters of the mixed solution at the inlet and outlet of the balance kettle 10.

[0069] S4, Real-time monitoring of the operating parameters of the compressor 1

[0070] S4.1, Start the compressor 1, set the suction pressure to 0.1 - 0.6 MPa, and the rotational speed of the compressor 1 to 1000 - 8000 r / min; control the ambient temperature within the range of -20 - 50 °C and continuously operate for 48 h. Open the back pressure valve 26 to maintain the system pressure stability and ensure safe operation. Start the cooling unit and maintain the outlet temperature of the compressor 1 within the set range (e.g., below 80 °C).

[0071] S4.2, Adjust the temperature of the electric heating calorimeter 29 between 20 - 40 °C. Its main function is to heat the CO before entering the compressor 1 2 to ensure its complete conversion to the gaseous state.

[0072] S4.3, During the operation of the compressor 1, use the performance parameter detection system (multiple temperature and pressure measurement points, mass flowmeter 27, ammeter, and voltmeter) to continuously monitor the following parameters: the inlet and outlet temperature and pressure of the compressor; the flow rate and density of the refrigerant; the input power of the compressor W = UI.

[0073] S4.4, Record the initial experimental conditions in real-time and repeat 5 times to ensure the stability and reliability of the data; then, through the control devices such as the temperature controller 32, back pressure valve 26, expansion valve 28, flow regulating valve 30, electronic three-way valve 6, electronic proportional valve 9, and temperature controller I14, adjust the operating temperature, pressure, and flow rate of the compressor, as well as the mixing ratio and temperature of the mixed solution, etc., to construct different experimental conditions. Through multi-condition testing, ensure the authenticity, repeatability, and reliability of the experimental data, providing a solid basis for the system performance evaluation.

[0074] S4.5, Collect the experimental data under various conditions and mark the time and condition.

[0075] S5, Analysis and evaluation of experimental data

[0076] S5.1, Organize the data of temperature, pressure, flow rate, and power, etc. under different refrigerant lubricant mixing ratios;

[0077] S5.2, Calculate and analyze the key evaluation parameters of the compressor operating performance under different mixing ratios, including the temperature difference between the inlet and outlet, refrigerating capacity, isentropic efficiency, system stability, operating life evaluation, etc., as well as possible problems (such as insufficient lubrication, power fluctuation, etc.). The specific calculation methods are as follows:

[0078] 1) Temperature difference between the inlet and outlet:

[0079] Δt = T out - T in

[0080] 2) Refrigerating capacity:

[0081] Q = Q m Δh

[0082] Among them, Q m is the mass flow rate, directly measured by the mass flowmeter II 27; according to the measured inlet and outlet pressures and temperatures, the corresponding specific enthalpy is obtained by using the thermodynamic software REFPROP, Δh = H in -H out .

[0083] 3) Isentropic efficiency:

[0084]

[0085] Among them, h 1 is the enthalpy value at the suction end of the compressor 1; h 2 ′ is the enthalpy value at the discharge end after isentropic compression; h 2 is the actual enthalpy value at the discharge end. A high isentropic efficiency represents less energy loss.

[0086] 4) Stability analysis: All key parameters (temperature, pressure, flow rate, and power) are monitored in real time, and the monitoring period (sampling once per minute) and the experimental duration (48 hours) are set to obtain stability data. The fluctuation amplitude of each parameter is calculated by the following formula:

[0087]

[0088] Among them: σ is the standard deviation of the parameter fluctuation; x i is the parameter value at the i-th sampling point; is the average value of the parameter. If the fluctuation amplitude is large, it indicates that the system stability is poor.

[0089] 5) Service life prediction: The compressor 1 is operated for a long time, and the performance parameters are periodically collected and the key evaluation parameters (such as the isentropic efficiency η s ) are calculated. The curve of the key evaluation parameter changing with time is plotted, and an exponential decay model is used for fitting to obtain the decay coefficient α:

[0090] η s (t) = η s (0)·e -αt

[0091] Among them, η s (t) is the performance parameter value at different times t obtained by data collection and calculation after continuous operation; η s (0) is the initial performance parameter value, that is, the performance when the compressor just starts to run; α is the decay coefficient, reflecting the rate of performance decline, obtained by fitting experimental data, with the unit of t -1 ; t is the running time.

[0092] Calculate the isentropic efficiency η of the compressor sThe time required to drop to 65% of the initial value. Meanwhile, lubricating oil samples in the compressor oil sump are regularly extracted to detect viscosity and other performance indicators (such as acid value, impurity content). When the lubricating oil viscosity drops to 90% of the initial value or the deterioration index reaches the failure standard, the lubrication state is judged to have failed. Finally, combining performance decay data, lubricating oil deterioration trend and mechanical performance indicators such as friction noise, comprehensively evaluate and more accurately predict the operating life of the compressor.

[0093] S5.3, Compare and analyze the influence of different mixing ratios on the operating performance of the compressor under various working conditions, and evaluate and obtain the optimal ratio of lubricating oil to refrigerant.

[0094] S6, Result optimization and application

[0095] S6.1, According to the analysis results of the experimental data, continue to adjust the mixing ratio of lubricating oil and refrigerant to determine the best ratio applicable to various compressor working conditions;

[0096] S6.2, Verify the applicability of the mixed solution after optimizing the ratio during the operation of the compressor to ensure the stability and reliability of its performance under different working conditions;

[0097] S6.3, Output the final experimental results to provide a reference basis for further optimizing the ratio of lubricating oil to refrigerant and improving the performance of the compressor.

[0098] In summary, the above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An online evaluation device for refrigerant / lubricant oil on compressor performance, characterized in that: include: Compressor (1), oil separator (2), oil cooler (3), filter (5), electronic three-way valve (6), oil storage tank (7), gas storage tank, electronic proportional valve (9), equilibrium kettle (10), capillary viscometer (11), constant temperature bath (12), temperature controller, mass flow meter, liquid phase gear pump (16), pressure sensor (17), platinum resistance (18), condenser (23), cooler (24), back pressure valve (26), expansion valve (28), electric heating calorimeter (29), flow control valve (30); The oil separator (2) is arranged at the outlet of the compressor (1) and is used to separate the lubricating oil and refrigerant discharged from the compressor (1); the compressor (1) and the oil separator (2) are placed in a constant temperature box (31), and the ambient temperature of the compressor (1) during operation is adjusted by a temperature controller II (32) to simulate operating conditions under different working conditions; The oil cooler (3) and the condenser (23) are respectively disposed at the oil outlet and the gas outlet of the oil separator (2) and are used to cool the separated lubricating oil and refrigerant; The cooler (24) is arranged at the outlet of the condenser (23) to further cool the refrigerant and then transport it to the gas storage tank II (25); the refrigerant is stored in the gas storage tank II (25); the refrigerant in the gas storage tank II (25) passes through the back pressure valve (26), the mass flow meter II (27), the expansion valve (28), the electric heating calorimeter (29) and the flow regulating valve (30) in sequence and enters the compressor (1); The filter (5) is placed at the outlet of the oil cooler (3); the oil storage tank (7) stores lubricating oil; the filter (5) and the oil storage tank (7) are connected to the balancing kettle (10) via an electronic three-way valve (6); the gas storage tank I (8) stores refrigerant and is connected to the balancing kettle (10) via an electronic proportional valve (9); the electronic proportional valve (9) and the electronic three-way valve (6) cooperate to control the mixing ratio of the lubricating oil and the refrigerant in the balancing kettle (10); The balance kettle (10) is used to prepare a uniform lubricant / refrigerant mixed solution; the lubricant / refrigerant mixed solution uniformly mixed in the balance kettle (10) is sequentially pumped into the compressor (1) through a capillary viscometer (11), a valve I (13), a temperature controller I (14), and a mass flow meter I (15) by a liquid phase gear pump (16); The inlet and outlet of the compressor (1) and the inlet and outlet of the balance kettle (10) are provided with a plurality of temperature measuring points and pressure measuring points, and a voltmeter and an ammeter are provided at the inlet of the compressor.

2. The device according to claim 1, characterized in that The oil cooler (3) and the condenser (23) perform heat exchange via cooling water provided by the water tank (4).

3. The device according to claim 1, characterized in that The balancing kettle (10) is placed in a circulating bath (21) and is kept at a constant temperature by a thermostatic bath (12); a platinum resistor (18) is used to monitor the temperature in the circulating bath (21) in real time.

4. The device according to claim 1, characterized in that The equilibrium kettle (10) is provided with an observation window and equipped with a camera (22) to monitor the mixing process of the lubricating oil and the refrigerant in real time and record the appearance and flow conditions of the mixed solution.

5. The device according to claim 1, characterized in that A pressure measuring point is set at the inlet and outlet of the capillary viscometer (11), and the dynamic viscosity of the mixed solution is calculated by measuring the pressure change at the inlet and outlet of the capillary viscometer (11) in combination with the Poiseuille formula.

6. The device according to claim 1 or 5, characterized in that When the low viscosity of the mixed solution is ≤100 mPa·s, a capillary viscometer (11) with a capillary diameter of 0.25 to 1 mm is used; when the low viscosity of the mixed solution is >100 mPa·s, a capillary viscometer (11) with a capillary diameter of 0.8 to 1.5 mm is used.

7. The device according to claim 1, characterized in that The mass ratio of the lubricating oil to the refrigerant in the equilibrium kettle (10) is between 99.5:0.5 and 96:

4.

8. The device according to claim 1 or 7, characterized in that The refrigerant is CO2 (R744), R290, R32, R134a, R1234ze (E) or R1234yf; the lubricant is ISO mineral oil, VG, POE or PVG.

9. The evaluation method of the online evaluation device for refrigerant / lubricant oil on compressor performance according to any one of claims 1 to 8, characterized in that: Step 1, controlling the electronic three-way valve (6) and the electronic proportional valve (9) so that the lubricating oil and the refrigerant are injected into the balancing kettle (10) according to a set mass ratio; the balancing kettle (10) is placed in a circulating bath (21), and the thermostatic bath (12) is started to control the ambient temperature at a set constant temperature environment so that the refrigerant and the lubricating oil are fully dissolved and mixed; Step 2, open valve I (13), and control the temperature of the mixed solution within a set range through temperature controller I (14); start the liquid phase gear pump (16) to inject the lubricating oil / refrigerant mixed solution into the compressor (1); the compressor (1) runs; open the back pressure valve (26), the expansion valve (28) and the flow regulating valve (30), and inject the refrigerant in the gas storage tank II (25) into the compressor (1); Step 3: Real-time recording of the temperature and pressure at the inlet of the equilibrium reactor (10) and the mass flow rate Q of the mixed solution at the outlet m , density ρ and viscosity η; real-time monitoring of compressor performance parameters, including input power, inlet and outlet temperature and pressure, refrigerant flow and density; Step 4, adjusting the back pressure valve (26), the flow regulating valve (30) and the temperature controller II (32) to adjust the compressor operating temperature, pressure and refrigerant flow; adjusting the electronic three-way valve (6) and the electronic proportional valve (9) to adjust the lubricant / refrigerant mass ratio, returning to step 1, and obtaining the compressor performance data under different compressor operating conditions and different lubricant / refrigerant mass ratio mixed solutions; Step 5, based on the monitored data, evaluating the operating efficiency, stability and service life of the compressor under different working conditions under different lubricant / refrigerant mass ratio mixed solutions; Determine the optimal lubricant / refrigerant mixed solution mass ratio for different compressor operating conditions.

10. The method according to claim 9, characterized in that By calculating the refrigeration capacity Q and isentropic efficiency η of the compressor s , evaluate the operating efficiency of the compressor; Run the compressor for a long time, collect its performance parameter data periodically, calculate the fluctuation range of each performance data, and evaluate the stability of the compressor; The compressor is run for a long time and its performance parameter data is collected periodically. The curve of key evaluation parameters changing with time is calculated and plotted. The exponential decay model is used for fitting to obtain the decay coefficient α and predict the life of the compressor.

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