Method and device for testing performance of dual-mode refrigerator and related equipment

Abstract

The application provides a dual-condition refrigerator performance test method, device and related equipment, and the method comprises the following steps: operating a dual-condition refrigerator under a first condition, collecting measured operation data of a compressor; based on the measured operation data, calculating a dimensionless mass flow coefficient by using a preset dimensionless mass flow coefficient expression, and constructing a normalized compressor characteristic curve; obtaining predicted working condition parameters of a second condition, and calculating a target pressure ratio under the second condition according to the predicted working condition parameters; based on the target pressure ratio and a first corresponding relationship, determining a target dimensionless mass flow coefficient under the second condition; based on the target dimensionless mass flow coefficient and a second corresponding relationship, determining a target isentropic compression efficiency under the second condition; and according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency, calculating a performance index under the second condition. The application can test the refrigeration characteristics of a higher-temperature working condition, and accurately predict the performance of a refrigerator under a low-temperature ice-making working condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration equipment performance testing, and in particular to a dual-working-condition refrigeration machine performance testing method and device and related equipment. BACKGROUND

[0002] A dual-working-condition refrigeration machine is a key device widely used in ice storage air conditioning systems, and needs to meet the operation requirements of both normal air conditioning working conditions and low-temperature ice-making working conditions. For the dual-working-condition refrigeration machine, the refrigerant outlet temperature usually needs to reach about -5.6℃ when operating in the ice-making working condition. Therefore, accurate testing of the performance in the ice-making working condition is a key to ensuring the quality of the equipment out of the factory.

[0003] In related technologies, most of the factory testing tables of refrigeration machine production factories only have water medium circulation test conditions and do not have refrigerant test conditions. Limited by the physical properties of water, only water can be used as refrigerated water medium to measure at a temperature greater than 3℃, so that the actual performance of the refrigeration machine in the ice-making working condition cannot be directly tested on the factory site. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a dual-working-condition refrigeration machine performance testing method and device and related equipment, which can accurately predict the performance of the refrigeration machine in the low-temperature ice-making working condition by testing the refrigeration characteristics in the higher-temperature air conditioning working condition.

[0005] In a first aspect, an embodiment of the present application provides a dual-working-condition refrigeration machine performance testing method, comprising:

[0006] running the dual-working-condition refrigeration machine in a first working condition, and collecting measured operating data of a compressor; wherein the condenser temperature of the first working condition is configured to cover the preset pressure ratio range of a second working condition in the operating pressure ratio range of the compressor in the first working condition;

[0007] based on the measured operating data, calculating a dimensionless mass flow coefficient by using a preset dimensionless mass flow coefficient expression, and constructing a normalized compressor characteristic curve according to the dimensionless mass flow coefficient; the normalized compressor characteristic curve comprises a first correspondence relationship between the pressure ratio and the dimensionless mass flow coefficient, and a second correspondence relationship between the isentropic compression efficiency and the dimensionless mass flow coefficient;

[0008] obtaining predicted working condition parameters of the second working condition, and calculating a target pressure ratio in the second working condition according to the predicted working condition parameters;

[0009] determining a target dimensionless mass flow coefficient in the second working condition based on the target pressure ratio and the first correspondence relationship;

[0010] determining a target isentropic compression efficiency of the second working condition based on the target dimensionless mass flow coefficient and the second corresponding relationship;

[0011] calculating a performance index of the dual-condition chiller in the second working condition according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency.

[0012] In some embodiments, the dual-condition chiller is operated in a first working condition, and measured operating data of the compressor is collected, including:

[0013] water medium is introduced into a chilled water circuit of the dual-condition chiller, and an outlet water temperature of a condenser of the dual-condition chiller is adjusted to a preset first temperature value; wherein the first temperature value is higher than a design condensing temperature of the dual-condition chiller in a rated air conditioning working condition;

[0014] under the condition that the first temperature value is kept constant, an outlet water temperature of an evaporator of the dual-condition chiller is adjusted to change in a preset outlet water temperature range, so that a ratio of a discharge pressure to a suction pressure of the compressor covers a design maximum pressure ratio and a choke flow critical pressure ratio in the second working condition;

[0015] During the change of the outlet water temperature of the evaporator, the inlet stagnation pressure, the inlet stagnation temperature, the discharge pressure, the discharge temperature of the compressor, and the refrigerating capacity of the dual-condition chiller are collected as the measured operating data.

[0016] In some embodiments, based on the measured operating data, a dimensionless mass flow coefficient is calculated by using a preset dimensionless mass flow coefficient expression, and a normalized compressor characteristic curve is constructed according to the dimensionless mass flow coefficient, including:

[0017] a specific refrigerant enthalpy at the compressor inlet is determined according to the inlet stagnation pressure and the inlet stagnation temperature in the measured operating data, and a specific refrigerant liquid enthalpy is determined according to the inlet stagnation pressure and a preset subcooling degree in the measured operating data;

[0018] a difference between the specific refrigerant enthalpy at the compressor inlet and the specific refrigerant liquid enthalpy is calculated to obtain a refrigerating capacity per unit mass of refrigerant;

[0019] a ratio of the refrigerating capacity in the measured operating data to the refrigerating capacity per unit mass of refrigerant is calculated to obtain a refrigerant mass flow in the first working condition;

[0020] a product of the refrigerant mass flow and a square root of the inlet stagnation temperature is taken as a dividend, and the inlet stagnation pressure of the compressor is taken as a divisor, so that a dimensionless mass flow coefficient corresponding to each measured working condition point in the first working condition is calculated;

[0021] A ratio of the exhaust pressure to the inlet stagnation pressure at each measured operating point is calculated to obtain a measured pressure ratio, and a mapping relationship between the measured pressure ratio and the dimensionless mass flow coefficient is established to obtain the first corresponding relationship;

[0022] According to the inlet stagnation pressure, the inlet stagnation temperature, the exhaust pressure and the exhaust temperature in the measured operating data, the actual enthalpy rise of the compressor is calculated, and according to the inlet stagnation pressure, the inlet stagnation temperature and the exhaust pressure, the isentropic enthalpy rise corresponding to the isentropic compression from the inlet state to the exhaust pressure is calculated;

[0023] The ratio of the isentropic enthalpy rise to the actual enthalpy rise is determined as a measured isentropic compression efficiency, and a mapping relationship between the measured isentropic compression efficiency and the dimensionless mass flow coefficient is established to obtain the second corresponding relationship.

[0024] In some embodiments, the predicted operating condition parameters of the second operating condition are obtained, and a target pressure ratio under the second operating condition is calculated according to the predicted operating condition parameters, which includes:

[0025] The set condenser temperature and the set evaporator temperature under the second operating condition are determined as the predicted operating condition parameters;

[0026] According to a preset refrigerant thermophysical property relationship, a condensation saturation pressure corresponding to the set condenser temperature and an evaporation saturation pressure corresponding to the set evaporator temperature are determined;

[0027] The ratio of the condensation saturation pressure to the evaporation saturation pressure is calculated to obtain the target pressure ratio under the second operating condition.

[0028] In some embodiments, the target dimensionless mass flow coefficient under the second operating condition is determined based on the target pressure ratio and the first corresponding relationship, which includes:

[0029] The target pressure ratio is taken as a query variable, and in the first corresponding relationship, a dimensionless mass flow coefficient value corresponding to the target pressure ratio is searched;

[0030] The obtained dimensionless mass flow coefficient value is determined as the target dimensionless mass flow coefficient under the second operating condition.

[0031] In some embodiments, the target isentropic compression efficiency under the second operating condition is determined based on the target dimensionless mass flow coefficient and the second corresponding relationship, which includes:

[0032] The target dimensionless mass flow coefficient is taken as a query variable, and in the second corresponding relationship, an isentropic compression efficiency value corresponding to the target dimensionless mass flow coefficient is searched;

[0033] The obtained isentropic compression efficiency value is determined as the target isentropic compression efficiency under the second working condition.

[0034] In some embodiments, the performance index of the dual-working-condition refrigeration machine under the second working condition is calculated according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency, including:

[0035] A predicted refrigerant mass flow under the second working condition is calculated according to the target dimensionless mass flow coefficient and the compressor inlet stagnation temperature and the compressor inlet stagnation pressure under the second working condition;

[0036] A refrigeration capacity per unit mass of refrigerant is calculated according to a refrigerant enthalpy difference between the evaporator inlet and outlet, and the refrigeration capacity of the dual-working-condition refrigeration machine is obtained by multiplying the predicted refrigerant mass flow and the refrigeration capacity per unit mass of refrigerant;

[0037] An isentropic compression ratio work is calculated according to the compressor inlet and outlet state parameters under the second working condition, and a coefficient of performance of the refrigerant cycle system is calculated in combination with the target isentropic compression efficiency;

[0038] A motor efficiency and a mechanical transmission efficiency corresponding to the second working condition are obtained, and a performance coefficient of the dual-working-condition refrigeration machine is calculated according to the motor efficiency, the mechanical transmission efficiency and the coefficient of performance of the refrigerant cycle system.

[0039] In a second aspect, the embodiments of the present application provide a dual-working-condition refrigeration machine performance testing device, including:

[0040] The acquisition module is configured to operate the dual-working-condition refrigeration machine under a first working condition and acquire measured operating data of the compressor; wherein a condenser temperature of the first working condition is configured to cover a preset pressure ratio range under a second working condition in a range of operating pressure ratios of the compressor under the first working condition.

[0041] The construction module is configured to calculate a dimensionless mass flow coefficient by using a preset dimensionless mass flow coefficient expression based on the measured operating data, and to construct a normalized compressor characteristic curve according to the dimensionless mass flow coefficient; the normalized compressor characteristic curve includes a first correspondence between a pressure ratio and the dimensionless mass flow coefficient, and a second correspondence between an isentropic compression efficiency and the dimensionless mass flow coefficient.

[0042] The first calculation module is configured to obtain predicted working condition parameters of the second working condition, and to calculate a target pressure ratio under the second working condition according to the predicted working condition parameters.

[0043] The first determination module is configured to determine a target dimensionless mass flow coefficient under the second working condition based on the target pressure ratio and the first correspondence.

[0044] determining, by a second determining module, a target isentropic compression efficiency in the second working condition based on the target dimensionless mass flow coefficient and the second correspondence;

[0045] calculating, by a second calculating module, a performance index of the dual-working-condition refrigeration machine in the second working condition according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency.

[0046] In a third aspect, an electronic device is provided, including a memory and a processor, the memory storing a computer program, and the processor implementing the dual-working-condition refrigeration machine performance testing method according to any one of the embodiments of the first aspect of the present application when executing the computer program.

[0047] In a fourth aspect, a computer readable storage medium is provided, the storage medium storing a program, and the program being executed by a processor to implement the dual-working-condition refrigeration machine performance testing method according to any one of the embodiments of the first aspect of the present application.

[0048] The dual-working-condition refrigeration machine performance testing method according to the embodiments of the present application has at least the following beneficial effects:

[0049] The dual-working-condition refrigeration machine performance testing method according to the embodiments of the present application includes: running the dual-working-condition refrigeration machine in a first working condition and collecting measured operation data of the compressor; wherein the condenser temperature of the first working condition is configured to cover the preset pressure ratio range of the second working condition in the operation pressure ratio range of the compressor in the first working condition; based on the measured operation data, a dimensionless mass flow coefficient is calculated by using a preset dimensionless mass flow coefficient expression, and a normalized compressor characteristic curve is constructed according to the dimensionless mass flow coefficient; the normalized compressor characteristic curve includes a first correspondence between the pressure ratio and the dimensionless mass flow coefficient, and a second correspondence between the isentropic compression efficiency and the dimensionless mass flow coefficient; a predicted working condition parameter of the second working condition is obtained, and a target pressure ratio in the second working condition is calculated according to the predicted working condition parameter; based on the target pressure ratio and the first correspondence, a target dimensionless mass flow coefficient in the second working condition is determined; based on the target dimensionless mass flow coefficient and the second correspondence, a target isentropic compression efficiency in the second working condition is determined; and according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency, a performance index of the dual-working-condition refrigeration machine in the second working condition is calculated.

[0050] The application can simulate the high pressure ratio operating environment required by the ice-making condition by using the conventional water medium in the factory environment without low-temperature frozen liquid test conditions, by operating the dual-condition refrigerator in the first working condition and configuring the condenser temperature so that the operating pressure ratio range covers the preset pressure ratio range in the second working condition. Then, by calculating the dimensionless mass flow coefficient by using the preset dimensionless mass flow coefficient expression, and constructing the normalized compressor characteristic curve, the influence of the compressor inlet state such as temperature and pressure on the performance curve can be eliminated, and a universal compressor characteristic model independent of the specific working condition temperature is established. Next, by obtaining the predicted working condition parameters of the second working condition and calculating the target pressure ratio, and then determining the target dimensionless mass flow coefficient and the target isentropic compression efficiency based on the normalized curve, the performance prediction of the low-temperature working condition can be converted into accurate mapping of the normalized characteristic curve, and the parameter conversion between different working conditions is realized. Finally, by calculating the performance indicators of the dual-condition refrigerator in the second working condition according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency, the quantitative calculation of the ice-making working condition performance is realized. Compared with the prior art which only makes qualitative judgment based on temperature difference assumption, the method provided by the application can quantitatively and accurately predict the performance of the refrigerator in the low-temperature ice-making working condition based on the similarity theory of centrifugal compressors by testing the air-conditioning working condition refrigeration characteristics at a higher temperature.

[0051] Additional aspects and advantages of the application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0052] The above and / or additional aspects and advantages of the application will become apparent and be readily appreciated from the following description, including the appended drawings, wherein:

[0053] Figure 1 A flowchart of an optional dual-condition refrigerator performance test method provided by an embodiment of the application;

[0054] Figure 2 A flowchart of another optional dual-condition refrigerator performance test method provided by an embodiment of the application;

[0055] Figure 3 A flowchart of another optional dual-condition refrigerator performance test method provided by an embodiment of the application;

[0056] Figure 4 A schematic diagram of the flow coefficient varying with the evaporator temperature provided by an embodiment of the application;

[0057] Figure 5 A schematic diagram of the pressure ratio varying with the flow coefficient curve provided by an embodiment of the application;

[0058] Figure 6A schematic diagram of an isentropic compression efficiency curve provided by an embodiment of the present application as a function of flow coefficient;

[0059] Figure 7 A flow chart of another optional dual-working-condition refrigeration machine performance test method provided by an embodiment of the present application;

[0060] Figure 8 A flow chart of another optional dual-working-condition refrigeration machine performance test method provided by an embodiment of the present application;

[0061] Figure 9 A flow chart of another optional dual-working-condition refrigeration machine performance test method provided by an embodiment of the present application;

[0062] Figure 10 A flow chart of another optional dual-working-condition refrigeration machine performance test method provided by an embodiment of the present application;

[0063] Figure 11 A schematic diagram of a dual-working-condition refrigeration machine performance test device provided by an embodiment of the present application;

[0064] Figure 12 A schematic diagram of a hardware structure of an electronic device provided by an embodiment of the present application;

[0065] Figure 13 A schematic diagram of performance prediction results of a dual-working-condition refrigeration machine provided by an embodiment of the present application at different condensing temperatures. DETAILED DESCRIPTION

[0066] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0067] In the description of the present application, the meaning of several is one or more, the meaning of multiple is two or more, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, second, it is only used to distinguish the technical features for the purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0068] In the description of the present application, it needs to be understood that the orientation description, such as the orientation or position relationship indicated by up, down, left, right, front, back and the like, is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0069] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present description, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0070] In the description of the present application, it needs to be explained that, unless otherwise explicitly limited, the words such as setting, installing, connecting and the like should be understood in a broad sense, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution. In addition, the identification of the specific steps in the following does not represent the limitation of the order and execution logic of the steps, and the execution order and execution logic between the steps should be understood and inferred with reference to the content expressed in the embodiments.

[0071] The dual-condition refrigerator is a key equipment widely used in ice storage air conditioning systems, which needs to meet the operation requirements of both normal air conditioning conditions and low-temperature ice making conditions. For the dual-condition refrigerator, the refrigerant outlet temperature usually needs to reach about -5.6℃ when operating in the ice making condition. Therefore, accurate testing of the performance under the ice making condition is the key to ensure the quality of the equipment out of the factory.

[0072] In the related art, most of the factory test benches of the refrigerator production factory only have water medium circulation test conditions, and do not have refrigerant test conditions. Limited by the physical properties of water, only water can be used as refrigerated water medium to measure at a temperature greater than 3℃, so that the actual performance of the refrigerator under the ice making condition cannot be directly tested on the factory site.

[0073] Based on this, this application, by operating a dual-condition refrigerator under a first operating condition and configuring the condenser temperature to cover the preset pressure ratio range under the second operating condition, can simulate the high-pressure ratio operating environment required for ice-making operations using conventional water media in factory environments lacking cryogenic refrigerant testing conditions. Then, by calculating the dimensionless mass flow coefficient using a preset dimensionless mass flow coefficient expression and constructing a normalized compressor characteristic curve, the influence of compressor inlet conditions such as temperature and pressure on the performance curve can be eliminated, establishing a universal compressor characteristic model independent of specific operating temperature. Next, by obtaining the predicted operating parameters for the second operating condition and calculating the target pressure ratio, and then determining the target dimensionless mass flow coefficient and target isentropic compression efficiency based on the normalized curve, the performance prediction for cryogenic conditions can be transformed into an accurate mapping of the normalized characteristic curve, realizing parameter conversion between different operating conditions. Finally, by calculating the performance indicators of the dual-condition refrigerator under the second operating condition based on the target dimensionless mass flow coefficient and target isentropic compression efficiency, quantitative calculation of the ice-making performance is achieved. Compared with existing technologies that rely solely on the assumption of temperature difference for qualitative judgment, the method provided in this application is based on the centrifugal compressor similarity theory. It can quantitatively and accurately predict the performance of a refrigeration unit under low-temperature ice-making conditions by testing the refrigeration characteristics of air conditioning under higher temperatures.

[0074] Please see Figure 1 The present invention provides a dual-condition refrigerator performance testing method, which may include, but is not limited to, the following steps 101 to 106:

[0075] Step 101: Run the dual-condition refrigeration unit under the first operating condition and collect the measured operating data of the compressor.

[0076] Step 102: Based on the measured operating data, the dimensionless mass flow coefficient is calculated using the preset dimensionless mass flow coefficient expression, and a normalized compressor characteristic curve is constructed based on the dimensionless mass flow coefficient.

[0077] Step 103: Obtain the predicted operating parameters for the second operating condition, and calculate the target pressure ratio under the second operating condition based on the predicted operating parameters.

[0078] Step 104: Based on the target pressure ratio and the first correspondence, determine the target dimensionless mass flow coefficient under the second operating condition.

[0079] Step 105: Based on the target dimensionless mass flow rate coefficient and the second correspondence, determine the target isentropic compression efficiency under the second operating condition.

[0080] Step 106: Calculate the performance index of the dual-condition refrigerator under the second condition based on the target dimensionless mass flow rate coefficient and the target isentropic compression efficiency.

[0081] In step 101 of some embodiments, the first working condition generally refers to the operating environment that can be achieved under the existing test conditions of the production plant, such as the air conditioning working condition using water as the refrigeration medium, and the second working condition refers to the low-temperature operating environment required in actual application, such as the ice-making working condition using glycol solution as the refrigerant. Due to the limitations of the physical properties of water, the chilled water temperature during plant testing is usually high. In order to simulate the harsh working conditions faced by the compressor in the ice-making working condition, the outlet water temperature of the condenser needs to be artificially increased, for example, adjusted to about 46 degrees Celsius, so that the discharge pressure of the compressor is increased. The operating pressure ratio refers to the ratio of the discharge pressure of the compressor to the suction pressure. By increasing the condensing temperature, the operating pressure ratio in the first working condition can reach or even exceed the pressure ratio level required in the ice-making working condition, for example, reach the range of 3.5 to 3.8, so as to cover the choking flow critical point, and ensure that the collected measured operating data contains the aerodynamic property data required in the ice-making working condition.

[0082] Please refer to Figure 2 In some embodiments, step 101 can include, but is not limited to, steps 201 to 203.

[0083] Step 201, water medium is introduced into the chilled water circuit of the dual-working-condition chiller, and the outlet water temperature of the condenser of the dual-working-condition chiller is adjusted to a preset first temperature value.

[0084] Step 202, under the condition of keeping the first temperature value constant, the outlet water temperature of the evaporator of the dual-working-condition chiller is adjusted to change in a preset outlet water temperature range, so that the ratio of the discharge pressure of the compressor to the suction pressure covers the design maximum pressure ratio and the choking flow critical pressure ratio in the second working condition.

[0085] Step 203, during the change of the outlet water temperature of the evaporator, the inlet stagnation pressure, the inlet stagnation temperature, the discharge pressure, the discharge temperature of the compressor, and the refrigerating capacity of the dual-working-condition chiller are collected as measured operating data.

[0086] In step 201 of some embodiments, in view of the fact that the refrigeration machine production factory usually only has the test condition of water medium, and limited by the freezing point physical property of water, the evaporator outlet water temperature during the test must be controlled above 0 degrees Celsius (for example, 3 to 5 degrees Celsius), which leads to the fact that the low suction pressure environment under the second working condition (ice making working condition, usually -5.6 degrees Celsius) cannot be directly reproduced. In order to simulate the high pressure ratio aerodynamic load borne by the compressor under the second working condition under the above limited conditions, the compensation must be made by increasing the exhaust pressure. Specifically, the condenser outlet water temperature is adjusted and stabilized at a preset first temperature value (for example, 46 degrees Celsius), which is significantly higher than the design condensing temperature (usually 30 to 40 degrees Celsius) of the double working condition refrigeration machine under the rated air conditioning working condition. By constructing this non-design point high condensing temperature environment, the compressor must overcome a higher condensing pressure while sucking in a higher temperature refrigerant gas, thereby forcing the operating pressure ratio of the compressor to be raised to a level (for example, 3.5 to 3.8) comparable to the actual ice making working condition, thereby laying a physical foundation for subsequent acquisition of equivalent aerodynamic performance data.

[0087] In step 202 of some embodiments, under the premise of maintaining the first temperature value constant to lock the high exhaust pressure, the evaporator outlet water temperature is continuously changed within a preset outlet water temperature range (for example, 2 to 4 degrees Celsius) by adjusting the heat load of the evaporator. The essence of this adjustment process is to change the suction pressure and inlet refrigerant density of the compressor, thereby driving the operating working condition point of the compressor to move on the characteristic map. The setting of the adjustment range must ensure that the ratio of the actually measured exhaust pressure to the suction pressure can completely cover the design maximum pressure ratio under the second working condition and the critical pressure ratio of choked flow. Among them, the design maximum pressure ratio corresponds to the maximum work required by the ice making compressor, and the critical pressure ratio of choked flow corresponds to the aerodynamic boundary state when the flow velocity of the compressor reaches the speed of sound. Covering these two key feature points can ensure that the collected data samples contain the complete aerodynamic change process from the normal compression region to the choked flow region, preventing the prediction distortion of the subsequent normalized model under the limit working condition due to data missing.

[0088] In step 203 of some embodiments, the data acquisition process aims to obtain core parameters for thermodynamic calculation and similarity normalization. The inlet stagnation pressure and the inlet stagnation temperature are collected because for a high-speed rotating centrifugal compressor, the kinetic energy of the fluid cannot be ignored, and the stagnation parameter can accurately represent the total energy state of the fluid, which is a necessary input variable for calculating the dimensionless mass flow coefficient (the product of the mass flow and the square root of the stagnation temperature divided by the stagnation pressure). At the same time, the exhaust pressure and the exhaust temperature are collected to determine the state of the compressed fluid, which can accurately calculate the actual enthalpy rise of the compression process combined with the thermophysical equation of the refrigerant. In addition, this embodiment collects the refrigerating capacity of the dual-working-condition refrigerator (usually obtained through the heat balance of the chilled water side) as measured data, rather than directly measuring the refrigerant mass flow, which is because direct measurement of refrigerant flow in a closed system is difficult and costly in engineering, while refrigerating capacity data is easy to obtain accurately through water side temperature difference and flow. Collecting this data provides a reliable basis for subsequent back calculation of refrigerant mass flow combined with unit refrigerating capacity. Through these measured parameters, not only does it avoid the engineering difficulty of directly measuring the refrigerant flow, but it also fully supports the calculation of measured pressure ratio and measured isentropic compression efficiency at each working point. Through these measured parameters, the measured pressure ratio and the measured isentropic compression efficiency (the ratio of isentropic enthalpy rise to actual enthalpy rise) at each working point can be calculated, thereby converting the physical layer running data into a thermodynamic data set reflecting the essential aerodynamic characteristics of the compressor.

[0089] Through steps 201 to 203 described above, the embodiment of the present application overcomes the technical obstacle of being unable to directly test low-temperature ice-making performance in the factory's conventional water medium test environment by using thermodynamic equivalence principles and establishing a high-temperature high-pressure ratio simulation operating environment. This method not only realizes complete coverage of key aerodynamic load points (including the design maximum pressure ratio point and the choke flow critical point) under ice-making conditions, but also obtains a complete data set containing stagnation parameters and thermodynamic state parameters. This provides complete measured data support for the normalization process based on the similarity principle of centrifugal compressors, so that the subsequent model can accurately back calculate the refrigerating capacity and energy efficiency indicators of the dual-working-condition refrigerator under low-temperature glycol conditions, ensuring the accuracy and scientificity of the factory performance test.

[0090] In step 102 of some embodiments, the dimensionless mass flow coefficient is a key parameter based on the similarity principle of centrifugal compressors, which is used to eliminate the influence of inlet temperature, inlet pressure and gas species on the performance curve, and is generally expressed as the product of mass flow and square root of inlet stagnation temperature divided by inlet stagnation pressure. By substituting the measured operating data collected at different temperatures and pressures into this expression, discrete test points can be unified into a normalized coordinate system. The normalized compressor characteristic curve constructed is essentially a set of universal performance maps, in which the first correspondence between pressure ratio and dimensionless mass flow coefficient reflects the variation of compressor power capacity with flow rate, and the second correspondence between isentropic compression efficiency and dimensionless mass flow coefficient reflects the variation of compressor aerodynamic efficiency with flow rate, which remains consistent under different inlet conditions, providing a theoretical basis for cross-condition prediction.

[0091] Please refer to Figure 3 In some embodiments, step 102 can include, but is not limited to, steps 301 to 307.

[0092] Step 301, according to the inlet stagnation pressure and inlet stagnation temperature in the measured operating data, the specific enthalpy of the compressor inlet refrigerant is determined, and according to the inlet stagnation pressure in the measured operating data and the preset subcooling degree, the specific enthalpy of the refrigerant liquid is determined.

[0093] Step 302, calculate the difference between the specific enthalpy of the compressor inlet refrigerant and the specific enthalpy of the refrigerant liquid, to get the refrigerating capacity per unit mass of refrigerant.

[0094] Step 303, calculate the ratio of the refrigerating capacity in the measured operating data to the refrigerating capacity per unit mass of refrigerant, to get the refrigerant mass flow under the first working condition.

[0095] Step 304, take the product of the refrigerant mass flow and the square root of the inlet stagnation temperature as the dividend, and take the compressor inlet stagnation pressure as the divisor, to calculate the dimensionless mass flow coefficient corresponding to each measured operating point under the first working condition.

[0096] Step 305, calculate the ratio of the discharge pressure to the inlet stagnation pressure under each measured operating point to get the measured pressure ratio, and establish a mapping relationship between the measured pressure ratio and the dimensionless mass flow coefficient to get the first correspondence.

[0097] Step 306, according to the inlet stagnation pressure, inlet stagnation temperature, discharge pressure and discharge temperature in the measured operating data, calculate the actual enthalpy rise of the compressor, and according to the inlet stagnation pressure, inlet stagnation temperature and discharge pressure, calculate the isentropic enthalpy rise corresponding to the isentropic compression from the inlet state to the discharge pressure.

[0098] Step 307: The ratio of isentropic enthalpy rise to actual enthalpy rise is determined as the measured isentropic compression efficiency, and a mapping relationship is established between the measured isentropic compression efficiency and the dimensionless mass flow rate coefficient to obtain the second correspondence relationship.

[0099] In step 301 of some embodiments, to establish the energy baseline of the refrigeration cycle, it is necessary to accurately calculate the thermodynamic state parameters of the refrigerant at key nodes. For the compressor inlet state, the measured inlet stagnation pressure and inlet stagnation temperature are substituted into the superheated gas specific enthalpy fitting equation of the refrigerant to calculate the compressor inlet refrigerant specific enthalpy. Simultaneously, for the refrigerant liquid state before the throttle valve, the liquid temperature can be determined by subtracting a preset subcooling from the saturation temperature corresponding to the condensing pressure, and the saturated liquid specific enthalpy at this temperature is used to approximate the refrigerant liquid specific enthalpy. This step, through high-precision property equations, provides accurate enthalpy input for subsequent calculations of the effective refrigeration energy density.

[0100] In step 302 of some embodiments, the cooling capacity per unit mass of refrigerant is... This represents the amount of heat that each kilogram of refrigerant can absorb during a phase change in the evaporator. Its calculation logic is based on the principle of energy conservation, and numerically equal to the difference between the gaseous specific enthalpy at the evaporator outlet (i.e., the compressor inlet) and the liquid specific enthalpy at the evaporator inlet (i.e., the throttle valve outlet). This difference directly reflects the effective heat absorption potential of the refrigerant under specific operating conditions.

[0101] In step 303 of some embodiments, to address the problems of high engineering difficulty, high cost, and interference with the flow field caused by directly measuring the refrigerant flow rate in a closed high-pressure refrigeration system, this embodiment adopts an indirect back-calculation strategy based on thermal balance. The overall cooling capacity Q (in kW) obtained in step 203 through water-side thermal balance (measuring chilled water flow rate and inlet / outlet water temperature difference) is divided by the unit mass cooling capacity calculated in step 302. (Unit: kJ / kg), thus accurately deriving the refrigerant mass flow rate under the first operating condition. This transforms easily measurable external energy data into internal fluid mass flow rate data that is difficult to measure directly, thus reducing the difficulty of implementing the test.

[0102] In step 304 of some embodiments, in order to unify the mass flow rate data under different operating conditions to the same evaluation standard, a dimensionless mass flow rate coefficient needs to be introduced for normalization. The calculation of this coefficient is based on the principle of fluid dynamics similarity, and the specific calculation expression is as follows:

[0103]

[0104] in, This indicates the refrigerant mass flow rate (unit: kg / s). represents the compressor inlet stagnation temperature (unit: K), represents the inlet stagnation pressure (unit: kPa). For a refrigeration centrifugal compressor, the evaporator temperature varies greatly (e.g., from -8℃ to 14℃), resulting in a dramatic change in the inlet gas density. Through the above formula, the refrigerant mass flow rate obtained by backstepping in the previous step is multiplied by the square root of the inlet stagnation temperature, and then divided by the inlet stagnation pressure, so that the performance data of different refrigeration temperatures and refrigerant types can be unified on a curve. As shown in FIG. 2, the data points measured at different evaporator temperatures (e.g., T1, T2, T3, T4, T5, and T6) show a highly consistent trend in the flow coefficient after calculation by the formula (about 2.7), thereby establishing the horizontal coordinate basis of the normalized characteristic curve. Figure 4

[0105] In step 305 of some embodiments, the measured pressure ratio is a key indicator reflecting the compressor's power, serving as the vertical coordinate in the characteristic curve. The calculation formula of the pressure ratio is generally expressed as:

[0106]

[0107] In the test scenario of the present embodiment, it is specifically embodied as the ratio of the exhaust pressure (or condenser pressure) to the inlet stagnation pressure. Based on the exhaust pressure and the inlet stagnation pressure collected in step 203, the measured pressure ratio of each operating point is calculated. The measured pressure ratio of each operating point is associated with the dimensionless mass flow coefficient calculated in step 301 as the horizontal coordinate, and the data of each measured operating point is fitted or plotted, as shown in FIG. 3, which shows the inherent law of the change of the pressure ratio with the flow coefficient under fixed guide vane opening (e.g., IGV = 100%, 80%, 60%, 40%), i.e., the first correspondence relationship. Since the horizontal coordinate has removed the influence of the inlet state, this curve reveals the energy head characteristics of the compressor impeller itself, so that the pressure ratio-flow relationship measured at high-temperature conditions can be directly used to represent the aerodynamic characteristics at low-temperature ice-making conditions. Figure 5

[0108] In step 306 of some embodiments, the calculation of the actual enthalpy rise and the isentropic enthalpy rise involves rigorous thermodynamic state equation solving, aiming to quantify the energy transfer in the compression process. The actual enthalpy rise refers to the actual specific enthalpy increment obtained by the refrigerant in the compression process, which is calculated by substituting the measured inlet stagnation pressure , inlet stagnation temperature , exhaust pressure , and exhaust temperature into the gaseous specific enthalpy fitting formula of the refrigerant (the polynomial form is ​​​), the import stagnation specific enthalpy and the exhaust specific enthalpy , and the difference between the two is the actual enthalpy rise . The isentropic enthalpy rise refers to the theoretical enthalpy increase assuming that the compression process has no entropy increase. The calculation process first calculates the import specific entropy according to the import state and the specific entropy fitting function , reverses the isentropic end temperature according to the isentropic condition and the exhaust pressure, and then substitutes the isentropic end specific enthalpy into the specific enthalpy formula to obtain the isentropic end specific enthalpy , and finally obtains the isentropic enthalpy rise

[0109] In step 307 of some embodiments, the measured isentropic compression efficiency is the core index for evaluating the aerodynamic perfection of the compressor, and its physical definition is the ratio of the isentropic compression work to the actual input shaft work. Based on the isentropic enthalpy rise and the actual enthalpy rise calculated in the previous step, the measured isentropic compression efficiency is calculated, and the formula is as follows:

[0110]

[0111] The efficiency value and the corresponding dimensionless mass flow coefficient are mapped to obtain the second corresponding relationship, i.e., the efficiency characteristic curve as shown in Figure 6 , which eliminates the influence of the absolute temperature level and reflects the law of the compressor efficiency changing with the relative flow. By establishing this relationship, in subsequent prediction, as long as the flow coefficient of the working condition point is determined, the aerodynamic efficiency under the working condition can be accurately obtained.

[0112] Through the above steps 301 to 307, the embodiment of the application constructs a normalized data processing model based on thermodynamic derivation. By introducing the dimensionless mass flow coefficient calculation expression as a similarity criterion formula, combined with high-precision solution of the refrigerant thermophysical property equation, the original measured data affected by the environment temperature are converted into the pressure ratio curve and the efficiency curve describing the essential aerodynamic characteristics of the compressor. These two curves constitute the core of the prediction model, so that the experimental data obtained at high-temperature water medium (such as 46℃ condensing temperature) can cross the temperature zone limit and be accurately mapped to the low-temperature ethylene glycol working condition (such as -6.2℃ evaporation temperature), thereby realizing quantitative backstepping and prediction of the performance index of the double-working-condition refrigerating machine under the ice-making working condition.

[0113] In step 103 of some embodiments, the predicted operating condition parameters refer to the operating conditions set for specific ice-making requirements, mainly including the set evaporator saturation temperature and the set condenser saturation temperature, for example, the evaporator temperature is set to negative 6.2 degrees Celsius to correspond to the ice-making operating condition. The target pressure ratio is an important indicator for evaluating the load level of the compressor under the predicted operating condition, which is calculated based on the thermophysical equation of the refrigerant, by looking up the saturation pressure corresponding to the set condenser temperature and the saturation pressure corresponding to the set evaporator temperature, and dividing the two to obtain the target pressure ratio. The target pressure ratio represents the compression capacity that the compressor needs to provide in the low-temperature ice-making scenario.

[0114] Please refer to Figure 7 In some embodiments, step 103 can include, but is not limited to, steps 701 to 703.

[0115] Step 701, determining the set condenser temperature and the set evaporator temperature under the second operating condition as the predicted operating condition parameters.

[0116] Step 702, according to the preset thermophysical relationship of the refrigerant, determining the condensation saturation pressure corresponding to the set condenser temperature and the evaporation saturation pressure corresponding to the set evaporator temperature.

[0117] Step 703, calculating the ratio of the condensation saturation pressure to the evaporation saturation pressure to obtain the target pressure ratio under the second operating condition.

[0118] In step 701 of some embodiments, in order to carry out performance prediction under the second operating condition, the thermodynamic boundary conditions of the second operating condition need to be determined first, that is, the set condenser temperature and the set evaporator temperature are determined. These two parameters form the basis of the predicted operating condition parameters. In the actual application scenario of the dual-condition refrigeration machine, the ice-making condition usually corresponds to an extremely low evaporation temperature (for example, the ethylene glycol outlet water temperature is negative 5.6 degrees Celsius, corresponding to a refrigerant saturation evaporation temperature of about negative 6.2 degrees Celsius) and a condensation temperature determined according to the cooling tower capacity (for example, 35 degrees Celsius). These two temperature values not only define the temperature span of the refrigeration cycle, but also are input variables for subsequent calculation of the thermophysical state of the refrigerant. By selecting these two key temperature parameters, the thermodynamic potential difference that the compressor must overcome in ice-making mode is determined, laying a foundation for subsequent conversion of external operating condition requirements into internal aerodynamic parameters.

[0119] In step 702 of some embodiments, based on the determined temperature parameters, the corresponding saturation pressure is calculated using the preset thermophysical relationship of the refrigerant. Since the refrigerant (such as R134a) in the saturated state of gas-liquid coexistence, its pressure is a single-valued function of temperature, which is usually accurately described by a high-order polynomial fitting equation. For example, the function relationship between the saturation pressure and the saturation temperature is The condensation saturation pressure is calculated by substituting the set condenser temperature into the equation, and the evaporation saturation pressure is calculated by substituting the set evaporator temperature into the equation. Compared with the simple table lookup method, this calculation method based on the thermophysical equation can avoid interpolation errors and accurately obtain the physical pressure value of the refrigerant at a specific working condition temperature, thereby accurately reflecting the pressure boundary of the high-pressure side and the low-pressure side of the refrigeration cycle.

[0120] In step 703 of some embodiments, the target pressure ratio is a key dimensionless parameter representing the aerodynamic pressure boosting capacity required to be provided by the centrifugal compressor at the predicted working condition. The calculation logic is to divide the condensation saturation pressure obtained in step 702 by the evaporation saturation pressure. In the ice-making working condition, the target pressure ratio usually reaches a high value (e.g., more than 3.5) due to the significant reduction of the evaporation saturation pressure. The significance of calculating the target pressure ratio is to use it as the ordinate index value for performance back-calculation using the normalized compressor characteristic curve. Only by accurately calculating this dimensionless pressure ratio, can the operating point of the compressor at the low-temperature working condition be accurately mapped in the subsequent steps through the first corresponding relationship (pressure ratio-flow coefficient curve), so as to determine the corresponding dimensionless mass flow coefficient.

[0121] Through steps 701 to 703 described above, the embodiments of the present application establish an accurate conversion logic from the working condition temperature parameter to the aerodynamic load parameter of the compressor. By introducing a high-precision refrigerant thermophysical equation, the temperature requirement of the low-temperature ice-making working condition is converted into an explicit physical pressure requirement, and further converted into a dimensionless target pressure ratio. This process eliminates the nonlinear influence of the ambient temperature on the load representation, ensures the accuracy of the prediction model input, and enables the subsequent reverse query based on the normalized curve to truly reflect the aerodynamic response of the compressor under extreme pressure difference, thereby providing a thermodynamic basis for realizing the quantitative prediction of the low-temperature performance of the dual-working-condition refrigeration machine.

[0122] In step 104 of some embodiments, since the normalized curve reveals the inherent physical relationship between the pressure ratio and the flow coefficient, when the target pressure ratio at the low-temperature working condition is determined, the pressure ratio value can be found on the ordinate axis of the first corresponding relationship curve, and the corresponding value on the abscissa axis is found, so as to determine the target dimensionless mass flow coefficient. This step maps the aerodynamic characteristics measured at the high-temperature high-pressure ratio working condition to the low-temperature high-pressure ratio working condition, thereby avoiding the difficulty of directly measuring the low-temperature flow.

[0123] Please refer to Figure 8 In some embodiments, step 104 can include, but is not limited to, steps 801 to 802.

[0124] In step 801, the target pressure ratio is used as a query variable to find the dimensionless mass flow coefficient value corresponding to the target pressure ratio in the first corresponding relationship.

[0125] Step 802, the obtained dimensionless mass flow coefficient value is determined as the target dimensionless mass flow coefficient under the second working condition.

[0126] In step 801 of some embodiments, the target pressure ratio calculated in the previous step is taken as an independent variable and substituted into the first correspondence relationship that has been constructed. The first correspondence relationship is a normalized pressure ratio characteristic curve constructed based on the first working condition measured data, which mathematically describes the function relationship (usually a monotonically decreasing relationship) of the pressure ratio of the centrifugal compressor with the dimensionless mass flow coefficient under a specific guide vane opening. Since the characteristic curve is constructed based on the similarity principle of the centrifugal compressor, the coupling effect of the inlet stagnation temperature and the stagnation pressure on the performance characterization is eliminated, and therefore the curve reveals the essential aerodynamic characteristics of the compressor impeller passage. The lookup process specifically embodies that the target pressure ratio value is located on the ordinate axis of the characteristic curve, and according to the function relationship, a unique corresponding value on the abscissa axis of the curve is determined. This process determines the aerodynamic operating point position of the compressor based on the thermodynamic load (pressure ratio).

[0127] In step 802 of some embodiments, the abscissa value determined through the above mapping relationship is defined as the target dimensionless mass flow coefficient under the second working condition. This coefficient is a similarity criterion number that comprehensively reflects the mass flow of the refrigerant, the inlet stagnation temperature, and the inlet stagnation pressure. In a physical sense, determining this coefficient means that the similarity state of the internal flow field of the compressor when it is running under the low-temperature ice-making working condition is equivalent to the state under the high-temperature test working condition. It is a key intermediate variable that connects the external thermodynamic load (pressure ratio) and the internal fluid mechanics performance (flow rate, efficiency), and provides the necessary input parameters for subsequent lookup of efficiency using the second correspondence relationship and back calculation of the actual physical mass flow.

[0128] Through steps 801 to 802 described above, the embodiments of the present application utilize the universality of the normalized compressor characteristic curve to establish an accurate mapping mechanism from the thermodynamic load parameter to the fluid mechanics characteristic parameter. By indexing the target pressure ratio, the compressor operating state point under the low-temperature working condition is accurately locked in the normalized space, and the corresponding dimensionless mass flow coefficient is obtained. This method effectively solves the problem of how to determine the compressor operating state based on the similarity principle when the flow rate under the low-temperature working condition cannot be directly measured, ensures that the subsequent performance prediction is based on a rigorous aerodynamic similarity state, and guarantees the physical consistency of the prediction results.

[0129] In step 105 of some embodiments, the target isentropic compression efficiency refers to the aerodynamic efficiency of the compressor under the predicted working condition, and is a key parameter for calculating the overall energy efficiency. Based on the target dimensionless mass flow coefficient determined in the previous step, the corresponding isentropic compression efficiency value can be obtained by looking up in the second corresponding relationship curve. The isentropic compression efficiency reflects the ratio of ideal isentropic compression work to actual compression work, and accurately reflects the internal fluid dynamics performance of the compressor under the low-temperature ice-making working condition without relying on rough empirical estimation.

[0130] Please refer to Figure 9 In some embodiments, step 105 can include, but is not limited to, steps 901 to 902.

[0131] In step 901, the target dimensionless mass flow coefficient is taken as a query variable to look up the isentropic compression efficiency value corresponding to the target dimensionless mass flow coefficient in the second corresponding relationship.

[0132] In step 902, the obtained isentropic compression efficiency value is determined as the target isentropic compression efficiency under the second working condition.

[0133] In step 901 of some embodiments, the target dimensionless mass flow coefficient determined in the previous step is taken as an independent query variable and substituted into the second corresponding relationship that has been constructed. The second corresponding relationship is a normalized isentropic compression efficiency characteristic curve constructed based on the first working condition measured data, with the dimensionless mass flow coefficient as the horizontal coordinate and the isentropic compression efficiency as the vertical coordinate. Since the curve is constructed based on the similarity principle of centrifugal compressors, it reveals the intrinsic law of the aerodynamic efficiency of the compressor changing with the relative flow, which does not drift with the absolute value of the inlet temperature or pressure. The lookup process specifically involves locating the target dimensionless mass flow coefficient value on the horizontal coordinate axis of the characteristic curve, and determining the unique corresponding value on the vertical coordinate axis according to the function trajectory of the curve. This process realizes the mapping from the fluid motion state (flow coefficient) to the energy conversion efficiency state (isentropic efficiency).

[0134] In step 902 of some embodiments, the vertical coordinate value obtained through the above mapping is confirmed as the target isentropic compression efficiency under the second working condition. This parameter physically represents the conversion rate of the mechanical work input into the compressor into effective aerodynamic potential energy under the low-temperature ice-making working condition. Although the refrigerant properties (such as density, sound speed) under the ice-making working condition are significantly different from those under the high-temperature test working condition, based on the similarity principle, their aerodynamic perfection is equivalent under the same dimensionless flow coefficient. Determining this efficiency value is a key step for subsequent calculation of the actual power consumption of the compressor and the overall energy efficiency of the refrigeration machine, and directly determines the accuracy of the prediction of the input power of the motor.

[0135] By the steps 901 to 902, the universality of the normalized efficiency curve is utilized to solve the technical problem that the internal aerodynamic efficiency of the compressor cannot be directly measured under the low-temperature working condition. The efficiency characteristics obtained in the high-temperature test are transferred to the low-temperature prediction model through the dimensionless mass flow coefficient, and the isentropic compression efficiency under the ice-making working condition is accurately obtained. This process completes the core energy consumption parameter in the performance prediction model, so that the actual shaft power and the energy efficiency coefficient can be calculated based on the thermodynamic formula, and the accuracy of the prediction of the energy efficiency indicators of the dual-working-condition refrigeration machine is ensured.

[0136] In step 106 of some embodiments, the performance indicators generally include the refrigeration capacity and the coefficient of performance COP of the refrigeration machine, and the calculation process involves reducing the dimensionless parameters to dimensioned physical quantities, using the target dimensionless mass flow coefficient to inversely calculate the actual mass flow of the refrigerant combined with the inlet conditions of the prediction working condition, and using the target isentropic compression efficiency and parameters such as motor efficiency and mechanical transmission efficiency to calculate the actual power consumption of the compressor and the heat absorption of the refrigerant side, and finally obtaining the quantitative performance data of the refrigeration machine under the low-temperature ice-making working condition, so as to realize the accurate prediction of the full-working-condition performance of the dual-working-condition main machine.

[0137] Please refer to Figure 10 In some embodiments, step 106 can include, but is not limited to, steps 1001 to 1004.

[0138] Step 1001, according to the target dimensionless mass flow coefficient and the compressor inlet stagnation temperature and the compressor inlet stagnation pressure under the second working condition, the predicted refrigerant mass flow under the second working condition is calculated.

[0139] Step 1002, according to the prediction working condition parameters to determine the refrigerant specific enthalpy difference between the evaporator inlet and outlet, calculate the refrigeration capacity per unit mass of refrigerant, and multiply the predicted refrigerant mass flow by the refrigeration capacity per unit mass of refrigerant to obtain the refrigeration capacity of the dual-working-condition refrigeration machine.

[0140] Step 1003, according to the compressor inlet and outlet state parameters under the second working condition to calculate the isentropic compression ratio work, and combine the target isentropic compression efficiency to calculate the energy efficiency coefficient of the refrigerant circulation system.

[0141] Step 1004, obtain the motor efficiency and mechanical transmission efficiency corresponding to the second working condition, and according to the motor efficiency, the mechanical transmission efficiency and the energy efficiency coefficient of the refrigerant circulation system, the performance coefficient of the dual-working-condition refrigeration machine is calculated.

[0142] In step 1001 of some embodiments, the process of predicting the refrigerant mass flow rate is essentially a reverse reduction using dimensionless parameters. The previously determined target dimensionless mass flow rate coefficient is a relative value. To obtain a physical flow rate with practical engineering significance, the specific intake state parameters under the second operating condition must be substituted. Specifically, based on the set evaporator temperature determined in the preceding steps and combined with the refrigerant thermophysical properties, the compressor inlet stagnation temperature and inlet stagnation pressure under the second operating condition are determined. The target dimensionless mass flow rate coefficient is multiplied by the inlet stagnation pressure and then divided by the square root of the inlet stagnation temperature to calculate the predicted refrigerant mass flow rate under the second operating condition. This step converts the normalized value based on the similarity principle back into the actual throughput capacity of the refrigeration unit under low-temperature ice-making conditions, i.e., the mass flow rate (kg / s).

[0143] In step 1002 of some embodiments, the calculation of the cooling capacity Q is based on the principle of energy conservation and depends on the refrigerant mass flow rate and the cooling capacity per unit mass. First, based on the predicted operating parameters (set evaporator temperature and set condenser temperature), the specific enthalpy of the gaseous refrigerant at the evaporator outlet (i.e., compressor inlet) and the specific enthalpy of the liquid refrigerant at the evaporator inlet (throttle valve outlet) are calculated using the refrigerant specific enthalpy fitting equation. The difference between the two is the heat absorbed per unit mass of refrigerant in the evaporator, which is the specific cooling capacity. Subsequently, the predicted refrigerant mass flow rate obtained in step 1001 is multiplied by this specific cooling capacity to obtain the predicted overall cooling capacity (kW) of the dual-condition refrigerator under the second operating condition. This calculation process combines the flow rate predicted by fluid dynamics and the enthalpy difference calculated by thermodynamics, achieving a quantitative assessment of the cooling capacity.

[0144] In step 1003 of some embodiments, the energy efficiency coefficient (EEC) of the refrigerant cycle system is... This mainly reflects the impact of compressor aerodynamic performance on cycle efficiency. Based on the compressor inlet state (determined by the set evaporator temperature) and discharge pressure (determined by the set condenser temperature) under the second operating condition, the predicted isentropic enthalpy rise under the second operating condition is calculated using the refrigerant thermophysical property equation. Predicting the isentropic enthalpy rise parameter Compared with the measured isentropic enthalpy rise in step 306 The calculation principle is the same. Since there are losses in the actual compression process, the target isentropic compression efficiency determined in the previous steps is used. After correcting the theoretical work, the actual aerodynamic specific work is obtained, as shown in the following formula:

[0145]

[0146] The energy efficiency coefficient of a refrigerant cycle system is defined as the ratio of specific cooling capacity to actual aerodynamic specific work. This indicator reflects the energy conversion efficiency at the thermodynamic cycle level, without taking into account mechanical and motor losses.

[0147] In step 1004 of some embodiments, in order to obtain the overall COP of the dual- working-condition chiller, the loss factor of mechanical transmission and motor conversion must be further introduced. The motor efficiency corresponding to the second working condition is obtained and the mechanical transmission efficiency wherein the mechanical transmission efficiency (especially the rolling bearing efficiency) is closely related to the evaporator saturation temperature, and is usually determined by an empirical formula. The final overall COP calculation formula is as follows:

[0148]

[0149] This step corrects the thermodynamic cycle efficiency to the final refrigeration efficiency, i.e., the ratio of refrigeration capacity to input electric power, thereby completing the final prediction of the actual energy consumption level of the equipment under the ice-making working condition.

[0150] In another more accurate implementation, especially for single-stage centrifugal compressors that use refrigerant to cool the bearing transmission, considering that the heat generated by mechanical friction consumes part of the evaporator refrigeration capacity, the calculation of the overall COP needs to deduct this part of the loss. At this time, the calculation formula is:

[0151]

[0152] In the formula, This item represents the energy efficiency loss due to the consumption of cold energy by bearing cooling. Through the use of this correction formula, the embodiments of the present application can more accurately predict the actual energy efficiency of the internally cooled centrifugal chiller under the ice-making working condition.

[0153] As Figure 13 shown, in some embodiments, using the normalized compressor characteristic curve model constructed by the foregoing steps, the complete performance map of the dual-working-condition chiller in the low-temperature region can be calculated and plotted. In the figure, the horizontal coordinate is the evaporator saturation temperature (unit: Celsius), the left vertical coordinate is the performance coefficient (COP) of the chiller unit, and the right vertical coordinate is the refrigeration capacity (Q, unit: kW) of the chiller. The solid line in the figure represents the predicted COP change trend at different condenser temperatures (for example, 35 degrees Celsius, 33 degrees Celsius, 31 degrees Celsius), and the dashed line represents the corresponding predicted refrigeration capacity Q change trend. As can be seen, as the evaporator temperature decreases, both the refrigeration capacity and the COP of the chiller show a downward trend, and the lower the condensing temperature, the better the performance at the same evaporating temperature.

[0154] In some embodiments, the "design ice-making condition" point is explicitly marked in the predicted result map (blue solid and hollow circles in the figure). For example, at a condenser temperature of 35 degrees Celsius and an evaporator temperature of about -6.2 degrees Celsius (corresponding to an ethylene glycol outlet temperature of -5.6 degrees Celsius), the application successfully predicts the refrigeration capacity and COP values at this point through the model. This means that although the actual factory test is carried out at high-temperature water medium (for example, condensing temperature of 46 degrees Celsius, evaporating temperature of 2 degrees Celsius or above), through the normalization prediction method of the application, the specific performance values of the refrigeration machine at the design target point (i.e. low-temperature ice-making condition) can be accurately back-calculated for comparison and verification with the design index.

[0155] In some embodiments, the map further predicts the operating boundaries of the refrigeration machine, including the "blocked flow boundary" and the "minimum evaporator temperature boundary". The blocked flow boundary (purple solid line in the figure) identifies the critical point at which the compressor enters the blocked flow state under different operating conditions. On the left side or above the boundary, the performance of the compressor will be limited by aerodynamic blocking. The minimum evaporator temperature boundary indicates the minimum evaporator temperature limit at which the refrigeration machine can safely operate at a certain condensing temperature (for example, at a condensing temperature of 31 degrees Celsius, the evaporating temperature can be as low as -9.2 degrees Celsius). With these boundary information, technicians can not only master the performance of a single operating condition, but also have a comprehensive understanding of the operating envelope of the dual-condition refrigeration machine in the low-temperature region, so as to judge its safety margin and adjustment potential when operating under variable conditions.

[0156] Through the above analysis of Figure 13 , the application embodiments show the final output results of the prediction method. The method breaks through the limitation that the factory cannot create a low-temperature test environment, and uses the similarity principle to convert high-temperature test data into quantitative performance curves under low-temperature operating conditions. This not only realizes the accurate prediction of the performance of the "design ice-making condition" point, verifies the product qualification, but also generates a panoramic performance map including the blocked flow boundary and the limit temperature, providing detailed data support for the optimization of the operation and control strategy of the dual-condition refrigeration machine in the actual ice storage system, greatly expanding the technical value of the factory test.

[0157] Through the steps 1001 to 1004, the embodiment of the present application completes the final conversion from the dimensionless characteristic parameter to the dimension engineering performance index. Through the combination of the specific thermodynamic boundary conditions of the second working condition, the flow coefficient and the efficiency parameter output by the normalization model are gradually restored to the refrigerant mass flow, the actual aerodynamic work and the refrigerating capacity of the whole machine. In particular, the motor efficiency and the mechanical transmission efficiency correction affected by temperature are introduced, which ensures that the prediction result not only contains the aerodynamic performance of the compressor, but also covers the actual loss of the mechanical transmission chain. This layer-by-layer progressive calculation logic realizes the quantitative and high-precision prediction of the refrigerating capacity (Q) and the energy efficiency coefficient (COP) of the dual-working-condition refrigerating machine in the low-temperature ice-making working condition, and provides performance checking data with high reference value for production factories that cannot perform low-temperature tests on real machines.

[0158] Please refer to Figure 11 The embodiment of the present application also provides a dual-working-condition refrigerating machine performance testing device, which can realize the dual-working-condition refrigerating machine performance testing method, and comprises:

[0159] A collection module is configured to run the dual-working-condition refrigerating machine in a first working condition and collect measured running data of the compressor; wherein the condenser temperature of the first working condition is configured to cover the preset pressure ratio range of the second working condition in the running pressure ratio range of the compressor in the first working condition.

[0160] A construction module is configured to calculate a dimensionless mass flow coefficient based on the measured running data by using a preset dimensionless mass flow coefficient expression, and to construct a normalized compressor characteristic curve according to the dimensionless mass flow coefficient; the normalized compressor characteristic curve comprises a first correspondence between the pressure ratio and the dimensionless mass flow coefficient, and a second correspondence between the isentropic compression efficiency and the dimensionless mass flow coefficient.

[0161] A first calculation module is configured to obtain a predicted working condition parameter of the second working condition, and to calculate a target pressure ratio in the second working condition according to the predicted working condition parameter.

[0162] A first determination module is configured to determine a target dimensionless mass flow coefficient in the second working condition based on the target pressure ratio and the first correspondence.

[0163] A second determination module is configured to determine a target isentropic compression efficiency in the second working condition based on the target dimensionless mass flow coefficient and the second correspondence.

[0164] A second calculation module is configured to calculate a performance index of the dual-working-condition refrigerating machine in the second working condition according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency.

[0165] The performance test method of the dual-condition refrigerator according to the embodiment of the present application comprises: running the dual-condition refrigerator in a first condition, and collecting measured operation data of the compressor; wherein the condenser temperature of the first condition is configured to make the operating pressure ratio range of the compressor in the first condition cover the preset pressure ratio range in a second condition; based on the measured operation data, the dimensionless mass flow coefficient is calculated by using a preset dimensionless mass flow coefficient expression, and the normalized compressor characteristic curve is constructed according to the dimensionless mass flow coefficient; the normalized compressor characteristic curve comprises a first correspondence relationship between the pressure ratio and the dimensionless mass flow coefficient, and a second correspondence relationship between the isentropic compression efficiency and the dimensionless mass flow coefficient; the predicted working condition parameters of the second condition are obtained, and the target pressure ratio in the second condition is calculated according to the predicted working condition parameters; based on the target pressure ratio and the first correspondence relationship, the target dimensionless mass flow coefficient in the second condition is determined; based on the target dimensionless mass flow coefficient and the second correspondence relationship, the target isentropic compression efficiency in the second condition is determined; and the performance index of the dual-condition refrigerator in the second condition is calculated according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency.

[0166] The present application runs the dual-condition refrigerator in the first condition, and configures the condenser temperature to make the operating pressure ratio range cover the preset pressure ratio range in the second condition, so that the high pressure ratio operating environment required by the ice-making condition can be simulated by using the conventional water medium in the factory environment without low-temperature refrigerant test conditions. Then, by calculating the dimensionless mass flow coefficient by using the preset dimensionless mass flow coefficient expression, and constructing the normalized compressor characteristic curve, the influence of the compressor inlet state such as temperature and pressure on the performance curve can be eliminated, and a universal compressor characteristic model independent of the specific working condition temperature is established. Next, by obtaining the predicted working condition parameters of the second condition and calculating the target pressure ratio, and then determining the target dimensionless mass flow coefficient and the target isentropic compression efficiency based on the normalized curve, the performance prediction of the low-temperature condition can be converted into accurate mapping of the normalized characteristic curve, and the parameter conversion between different conditions is realized. Finally, by calculating the performance index of the dual-condition refrigerator in the second condition according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency, the quantitative calculation of the ice-making condition performance is realized. Compared with the qualitative judgment based on the temperature difference assumption in the prior art, the method provided in the embodiment of the present application can quantitatively and accurately predict the performance of the refrigerator in the low-temperature ice-making condition by testing the air-conditioning condition refrigeration characteristics at a higher temperature based on the similarity theory of centrifugal compressors.

[0167] Reference Figure 12 , Figure 12 The hardware structure of the electronic device of another embodiment is illustrated, and the electronic device comprises:

[0168] The processor 1201 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits, and is configured to execute related programs to implement the technical solutions provided by the embodiments of the present application.

[0169] The memory 1202 can be implemented by a ROM (Read-Only Memory), a static storage device, a dynamic storage device, or a RAM (Random Access Memory), etc. The memory 1202 can store an operating system and other application programs. When the technical solutions provided by the embodiments of the present application are implemented by software or firmware, the related program codes are stored in the memory 1202 and are called and executed by the processor 1201 to implement the double-working-condition refrigeration machine performance test method of the embodiments of the present application.

[0170] The input / output interface 1203 is configured to implement information input and output.

[0171] The communication interface 1204 is configured to implement the communication interaction between the device and other devices. The communication can be implemented by a wired manner (for example, a USB, a network cable, etc.) or a wireless manner (for example, a mobile network, Wi-Fi, Bluetooth, etc.).

[0172] The bus 1205 is configured to transmit information between various components (for example, the processor 1201, the memory 1202, the input / output interface 1203, and the communication interface 1204) of the device.

[0173] The processor 1201, the memory 1202, the input / output interface 1203, and the communication interface 1204 are connected to each other by the bus 1205 to realize the communication connection between the device.

[0174] The embodiments of the present application further provide a computer program product, which includes a computer program. The processor of the computer device reads the computer program and executes it, so that the computer device executes the double-working-condition refrigeration machine performance test method.

[0175] The terms "first", "second", "third", "fourth", and the like in the description of the disclosure and the above drawings, if any, are used to distinguish similar objects, and do not necessarily have to be used to describe a particular order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the disclosure described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "contain" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device containing a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0176] It should be understood that in the present disclosure, "at least one" means one or more, and "multiple" means two or more. "And / or" is used to describe the relationship between the associated objects, which means that there can be three relationships, for example, "A and / or B" can mean that there are three cases: only A, only B, and A and B at the same time, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0177] It should be understood that in the description of the embodiments of the present application, the meaning of multiple (or multiple) is two or more, greater than, less than, more than, etc. is not included in the number, above, below, etc. is understood to include the number.

[0178] In several embodiments provided by the present disclosure, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and actual implementation can have another division manner, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displayed or discussed objects can be indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0179] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, i.e., may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0180] In addition, each functional unit in various embodiments of the present disclosure can be integrated into one processing unit, or each unit can exist physically, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0181] If the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present disclosure essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present disclosure. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0182] It should also be appreciated that the various embodiments provided by the present application can be combined in any way to achieve different technical effects.

[0183] The above is a specific description of the embodiments of the present disclosure, but the present disclosure is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the present disclosure, and these equivalent modifications or replacements are included in the scope defined by the claims of the present disclosure.

Claims

1. A method of testing the performance of a dual- duty refrigerator, characterized in that, Comprise: In the first operating condition, the operating data of the compressor are collected, including: water medium is introduced into the chilled water circuit of the dual-condition chiller, and the outlet water temperature of the condenser of the dual-condition chiller is adjusted to a preset first temperature value; wherein the first temperature value is higher than the design condensing temperature of the dual-condition chiller under the rated air conditioning operating condition; under the condition that the first temperature value is kept constant, the outlet water temperature of the evaporator of the dual-condition chiller is adjusted to change in a preset outlet water temperature range, so that the ratio of the discharge pressure to the suction pressure of the compressor covers the design maximum pressure ratio and the choke flow critical pressure ratio under the second operating condition; during the change of the outlet water temperature of the evaporator, the inlet stagnation pressure, the inlet stagnation temperature, the discharge pressure, the discharge temperature of the compressor and the refrigerating capacity of the dual-condition chiller are collected as the measured operating data; wherein the outlet water temperature of the condenser of the first operating condition is configured so that the operating pressure ratio range of the compressor under the first operating condition covers the preset pressure ratio range under the second operating condition; Based on the measured operating data, the dimensionless mass flow coefficient is calculated by using a preset dimensionless mass flow coefficient expression, and a normalized compressor characteristic curve is constructed according to the dimensionless mass flow coefficient; the normalized compressor characteristic curve comprises a first correspondence between the pressure ratio and the dimensionless mass flow coefficient, and a second correspondence between the isentropic compression efficiency and the dimensionless mass flow coefficient; specifically comprising: according to the inlet stagnation pressure and the inlet stagnation temperature in the measured operating data, the specific enthalpy of the compressor inlet refrigerant is determined, and according to the inlet stagnation pressure and the preset supercooling degree in the measured operating data, the specific enthalpy of the refrigerant liquid is determined; the difference between the specific enthalpy of the compressor inlet refrigerant and the specific enthalpy of the refrigerant liquid is calculated to obtain the refrigerating capacity per unit mass of refrigerant; the ratio of the refrigerating capacity in the measured operating data to the refrigerating capacity per unit mass of refrigerant is calculated to obtain the refrigerant mass flow under the first operating condition; the product of the refrigerant mass flow and the square root of the inlet stagnation temperature is taken as the dividend, and the compressor inlet stagnation pressure is taken as the divisor to calculate the dimensionless mass flow coefficient corresponding to each measured operating condition point under the first operating condition; the ratio of the discharge pressure to the inlet stagnation pressure under each measured operating condition point is calculated to obtain the measured pressure ratio, and a mapping relationship between the measured pressure ratio and the dimensionless mass flow coefficient is established to obtain the first correspondence; according to the inlet stagnation pressure, the inlet stagnation temperature, the discharge pressure and the discharge temperature in the measured operating data, the actual enthalpy rise of the compressor is calculated, and according to the inlet stagnation pressure, the inlet stagnation temperature and the discharge pressure, the isentropic enthalpy rise corresponding to the isentropic compression from the inlet state to the discharge pressure is calculated; the ratio of the isentropic enthalpy rise to the actual enthalpy rise is determined as the measured isentropic compression efficiency, and a mapping relationship between the measured isentropic compression efficiency and the dimensionless mass flow coefficient is established to obtain the second correspondence; obtaining a predicted operating condition parameter of the second operating condition, and calculating a target pressure ratio of the second operating condition according to the predicted operating condition parameter; determining a target dimensionless mass flow coefficient of the second operating condition based on the target pressure ratio and the first corresponding relationship; determining a target isentropic compression efficiency of the second operating condition based on the target dimensionless mass flow coefficient and the second corresponding relationship; calculating a performance index of the dual-condition refrigeration machine in the second operating condition according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency.

2. The dual-cycle refrigerator performance test method of claim 1, wherein, The obtaining a predicted operating condition parameter of the second operating condition, and calculating a target pressure ratio of the second operating condition according to the predicted operating condition parameter, comprises: determining a set condenser outlet water temperature and a set evaporator outlet water temperature of the second operating condition as the predicted operating condition parameter; determining a condensation saturation pressure corresponding to the set condenser outlet water temperature and an evaporation saturation pressure corresponding to the set evaporator outlet water temperature according to a preset refrigerant thermophysical property relationship; calculating a ratio of the condensation saturation pressure to the evaporation saturation pressure to obtain the target pressure ratio of the second operating condition.

3. The dual-cycle refrigerator performance test method of claim 1, wherein, The determining a target dimensionless mass flow coefficient of the second operating condition based on the target pressure ratio and the first corresponding relationship, comprises: taking the target pressure ratio as a query variable, and searching for a dimensionless mass flow coefficient value corresponding to the target pressure ratio in the first corresponding relationship; determining the obtained dimensionless mass flow coefficient value as the target dimensionless mass flow coefficient of the second operating condition.

4. The dual-cycle refrigerator performance test method of claim 1, wherein, The determining a target isentropic compression efficiency of the second operating condition based on the target dimensionless mass flow coefficient and the second corresponding relationship, comprises: taking the target dimensionless mass flow coefficient as a query variable, and searching for an isentropic compression efficiency value corresponding to the target dimensionless mass flow coefficient in the second corresponding relationship; determining the obtained isentropic compression efficiency value as the target isentropic compression efficiency of the second operating condition.

5. The dual-cycle refrigerator performance test method of claim 1, wherein, The calculating a performance index of the dual-condition refrigeration machine in the second operating condition according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency, comprises: calculating a predicted refrigerant mass flow in the second operating condition according to the target dimensionless mass flow coefficient, a compressor inlet stagnation temperature and a compressor inlet stagnation pressure in the second operating condition; calculating a refrigeration capacity of unit mass refrigerant according to a refrigerant specific enthalpy difference of an evaporator inlet and outlet determined according to the predicted operating condition parameter, and multiplying the predicted refrigerant mass flow by the refrigeration capacity of unit mass refrigerant to obtain a refrigeration capacity of the dual-condition refrigeration machine; calculating an isentropic compression specific work according to compressor inlet and outlet state parameters in the second operating condition, and combining the target isentropic compression efficiency to calculate an energy efficiency coefficient of a refrigerant circulation system; obtaining a motor efficiency and a mechanical transmission efficiency corresponding to the second operating condition, and calculating a performance coefficient of the dual-condition refrigeration machine according to the motor efficiency, the mechanical transmission efficiency and the energy efficiency coefficient of the refrigerant circulation system.

6. A dual-cycle refrigerator performance testing apparatus, characterized by, comprises: The acquisition module is configured to acquire measured operating data of the compressor when the dual-mode chiller is operated in the first working condition, including: introducing water medium into a chilled water circuit of the dual-mode chiller, and adjusting a condenser outlet water temperature of the dual-mode chiller to a preset first temperature value; wherein the first temperature value is higher than a design condensing temperature of the dual-mode chiller in a rated air conditioning working condition; under the condition that the first temperature value is kept constant, adjusting an evaporator outlet water temperature of the dual-mode chiller to change in a preset outlet water temperature range, so that a ratio of discharge pressure to suction pressure of the compressor covers a design maximum pressure ratio and a choked flow critical pressure ratio in the second working condition; during the change of the evaporator outlet water temperature, acquiring inlet stagnation pressure, inlet stagnation temperature, discharge pressure, discharge temperature of the compressor, and refrigerating capacity of the dual-mode chiller as the measured operating data; wherein the condenser outlet water temperature of the first working condition is configured to make the operating pressure ratio range of the compressor in the first working condition cover the preset pressure ratio range in the second working condition; The construction module is configured to calculate a dimensionless mass flow coefficient based on the measured operating data by using a preset dimensionless mass flow coefficient expression, and construct a normalized compressor characteristic curve according to the dimensionless mass flow coefficient; the normalized compressor characteristic curve includes a first correspondence relationship between pressure ratio and dimensionless mass flow coefficient, and a second correspondence relationship between isentropic compression efficiency and dimensionless mass flow coefficient; specifically including: determining compressor inlet refrigerant specific enthalpy according to inlet stagnation pressure and inlet stagnation temperature in the measured operating data, and determining refrigerant liquid specific enthalpy according to inlet stagnation pressure in the measured operating data and a preset subcooling degree; calculating a difference between the compressor inlet refrigerant specific enthalpy and the refrigerant liquid specific enthalpy to obtain refrigerating capacity per unit mass of refrigerant; calculating a ratio of the refrigerating capacity in the measured operating data to the refrigerating capacity per unit mass of refrigerant to obtain refrigerant mass flow in the first working condition; calculating the dimensionless mass flow coefficient corresponding to each measured working condition point in the first working condition by taking the product of the refrigerant mass flow and the square root of the inlet stagnation temperature as the dividend, and taking the compressor inlet stagnation pressure as the divisor; calculating a measured pressure ratio by calculating a ratio of discharge pressure to inlet stagnation pressure at each measured working condition point, and establishing a mapping relationship between the measured pressure ratio and the dimensionless mass flow coefficient to obtain the first correspondence relationship; calculating actual enthalpy rise of the compressor according to inlet stagnation pressure, inlet stagnation temperature, discharge pressure and discharge temperature in the measured operating data, and calculating isentropic enthalpy rise corresponding to isentropic compression from an inlet state to the discharge pressure according to the inlet stagnation pressure, the inlet stagnation temperature and the discharge pressure; determining a measured isentropic compression efficiency as a ratio of the isentropic enthalpy rise to the actual enthalpy rise, and establishing a mapping relationship between the measured isentropic compression efficiency and the dimensionless mass flow coefficient to obtain the second correspondence relationship; The first calculation module is configured to obtain a predicted working condition parameter of the second working condition, and calculate a target pressure ratio in the second working condition according to the predicted working condition parameter; The first determination module is configured to determine a target dimensionless mass flow coefficient in the second working condition based on the target pressure ratio and the first corresponding relationship; The second determination module is configured to determine a target isentropic compression efficiency in the second working condition based on the target dimensionless mass flow coefficient and the second corresponding relationship; The second calculation module is configured to calculate a performance index of the dual-working-condition refrigerator in the second working condition according to the target dimensionless mass flow coefficient and the target isentropic compression efficiency.

7. An electronic device, comprising: The dual-working-condition refrigerator performance test method comprises: A memory and a processor, wherein the memory stores a computer program, and the processor implements the dual-working-condition refrigerator performance test method according to any one of claims 1 to 5 when executing the computer program.

8. A computer-readable storage medium, characterized in that, The storage medium stores a program, and the program is executed by the processor to implement the dual-working-condition refrigerator performance test method according to any one of claims 1 to 5.

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