Compressor performance prediction method and device, electronic equipment and storage medium

Abstract

The embodiment of the application provides a kind of compressor performance prediction method, device, electronic equipment and storage medium, belong to compressor control technical field.The method comprises: obtaining the thermodynamic state parameter of target compressor under a plurality of preset operating test conditions;Wherein, the thermodynamic state parameter includes the operating parameter of target compressor under the condition of blocked flow;Based on the thermodynamic state parameter, the normalized flow coefficient corresponding to the target compressor is constructed;Based on the normalized flow coefficient, a characteristic relationship curve is constructed to obtain a normalized characteristic relationship curve;Obtain the target operating parameter of target compressor under target condition, based on the target operating parameter and the normalized characteristic relationship curve, performance analysis is carried out, and the target performance information of target compressor under the target condition is obtained.The embodiment of the application can better quantitatively analyze the performance of compressor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compressor control, and particularly relates to a compressor performance prediction method and device, an electronic device and a storage medium. BACKGROUND

[0002] As a core component of a centrifugal refrigeration unit, the performance characteristic curve of a centrifugal compressor is an important basis for compressor design, operation guidance and fault diagnosis. Generally, the performance characteristic curve of a compressor needs to be obtained by specific bench testing in a production factory. However, in actual applications, the centrifugal compressor is part of a refrigeration unit, which makes it difficult for users to analyze the operation state of the refrigeration system based on the characteristics of the compressor itself.

[0003] In the prior art, when constructing the performance characteristic curve of a compressor, the volumetric flow rate or the refrigerant flow rate coefficient is usually used as the horizontal coordinate. These parameters are greatly affected by the inlet temperature, pressure and refrigerant type of the compressor, which makes it difficult to evaluate the data measured under different working conditions according to the same standard, which makes it very difficult to design and analyze the performance of the compressor.

[0004] In addition, for a dual-working-condition refrigeration unit, it is usually operated in a choked flow condition. However, the prior art lacks analysis of the choked flow characteristics of the refrigeration compressor, there is no effective method to determine the choked flow critical point, and it is also impossible to predict the refrigeration capacity and critical temperature of the refrigeration compressor based on the choked flow characteristics, which limits the optimization and fault diagnosis of the internal operating parameters of the refrigeration compressor. Therefore, how to quantitatively analyze the performance of the compressor and obtain more accurate evaluation data reflecting the performance of the compressor has become a technical problem to be solved. SUMMARY

[0005] The main purpose of the embodiments of the present application is to provide a compressor performance prediction method, device, electronic device and storage medium, which can better quantitatively analyze the performance of the compressor.

[0006] To achieve the above-mentioned purpose, a first aspect of the embodiments of the present application provides a compressor performance prediction method, which comprises the following steps:

[0007] acquiring thermodynamic state parameters of a target compressor under a plurality of preset operating test conditions; wherein the thermodynamic state parameters include operating parameters of the target compressor under a choked flow condition;

[0008] constructing a normalized flow rate coefficient corresponding to the target compressor based on the thermodynamic state parameters;

[0009] constructing a characteristic relationship curve based on the normalized flow rate coefficient to obtain a normalized characteristic relationship curve;

[0010] obtaining a target operating parameter of the target compressor under a target working condition, performing performance analysis based on the target operating parameter and the normalized characteristic relation curve, and obtaining target performance information of the target compressor under the target working condition.

[0011] In some embodiments, the thermodynamic state parameters at least include an evaporator saturation temperature and a refrigeration capacity of the refrigeration machine, and the constructing of the normalized flow coefficient corresponding to the target compressor based on the thermodynamic state parameters comprises:

[0012] obtaining a refrigerant mass flow rate based on the refrigeration capacity and preset refrigerant thermophysical parameters;

[0013] constructing a normalized flow coefficient based on the refrigerant mass flow rate and the evaporator saturation temperature; wherein the normalized flow coefficient is used to eliminate the influence of the target compressor inlet state on the normalized characteristic relation curve.

[0014] In some embodiments, the thermodynamic state parameters further include a condenser saturation temperature, and the obtaining of the refrigerant mass flow rate based on the refrigeration capacity and preset refrigerant thermophysical parameters comprises:

[0015] constructing a thermophysical equation of the refrigerant according to the refrigerant thermophysical parameters;

[0016] determining an inlet guide vane inlet specific enthalpy based on the thermophysical equation and the evaporator saturation temperature;

[0017] determining a throttle valve inlet specific enthalpy based on the thermophysical equation and the condenser saturation temperature;

[0018] determining the refrigerant mass flow rate based on a ratio of the refrigeration capacity to a difference between the inlet and outlet specific enthalpies.

[0019] In some embodiments, the constructing of the characteristic relation curve based on the normalized flow coefficient comprises:

[0020] obtaining an evaporator pressure and a condenser pressure;

[0021] obtaining a compressor pressure ratio based on the evaporator pressure and the condenser pressure;

[0022] constructing the normalized characteristic relation curve corresponding to the target compressor based on the compressor pressure ratio and the normalized flow coefficient;

[0023] and / or, calculating a single-stage isentropic compression efficiency based on the thermodynamic state parameters and the thermophysical equation of the refrigerant;

[0024] constructing a normalized characteristic curve of the isentropic compression efficiency varying with the normalized flow coefficient based on the single-stage isentropic compression efficiency. In some embodiments, the method further comprises:

[0025] identifying a region in the normalized characteristic curve where the normalized flow coefficient remains constant as the compressor pressure ratio decreases, determining as a choked flow condition region;

[0026] determining the normalized flow coefficient corresponding to the choked flow condition region as a choked flow flow coefficient, and determining the compressor pressure ratio entering the choked flow condition region as a choked flow critical pressure ratio.

[0027] In some embodiments, the performance analysis based on the target operating parameters and the normalized characteristic curve obtains target performance information of the target compressor under the target operating condition, including:

[0028] performance analysis based on the target operating parameters and the normalized characteristic curve;

[0029] when it is determined that the target compressor is in the choked flow condition region, determining the current measured evaporator saturation temperature based on the choked flow flow coefficient as a fixed input according to the target operating parameters, and inversely calculating the corresponding refrigerant mass flow rate;

[0030] based on the current measured inlet and outlet enthalpy difference, calculating the predicted refrigeration capacity, thereby evaluating the target performance information of the refrigeration machine under the choked flow condition.

[0031] In some embodiments, the method further comprises:

[0032] obtaining a real-time normalized flow coefficient under the target operating condition based on the target operating parameters;

[0033] in the normalized characteristic curve, finding a theoretical isentropic compression efficiency corresponding to the real-time normalized flow coefficient;

[0034] obtaining a real-time isentropic compression efficiency under the target operating condition;

[0035] based on the real-time isentropic compression efficiency and the theoretical isentropic compression efficiency, performing energy efficiency evaluation to generate energy efficiency evaluation information.

[0036] To achieve the above-mentioned purpose, a second aspect of the embodiment of the present application proposes a compressor performance prediction device, the device comprising:

[0037] a data acquisition module configured to acquire thermodynamic state parameters of a target compressor under a plurality of preset operating test conditions; wherein the thermodynamic state parameters include operating parameters of the target compressor under a choked flow condition;

[0038] a flow coefficient constructing module configured to construct a normalized flow coefficient corresponding to the target compressor based on the thermodynamic state parameters;

[0039] a normalized characteristic curve constructing module configured to construct a characteristic curve based on the normalized flow coefficient, to obtain a normalized characteristic curve;

[0040] a performance prediction module configured to obtain a target operating parameter of the target compressor under a target working condition, to perform performance analysis based on the target operating parameter and the normalized characteristic curve, and to obtain target performance information of the target compressor under the target working condition.

[0041] To achieve the above object, a third aspect of embodiments of the present application provides an electronic device, which comprises a memory and a processor, the memory stores a computer program, and the processor implements the compressor performance prediction method of the first aspect when executing the computer program.

[0042] To achieve the above object, a fourth aspect of embodiments of the present application provides a computer readable storage medium, which stores a computer program, and the computer program implements the compressor performance prediction method of the first aspect when executed by a processor.

[0043] The compressor performance prediction method, device, electronic device and storage medium provided by the present application can eliminate or mathematically compensate the deviation caused by different inlet conditions by constructing the normalized flow coefficient, thereby establishing a set of universal evaluation standards independent of the inlet condition, so that the data measured under different conditions are comparable, and the problem of difficult compressor performance design and analysis is solved. In addition, by including the choked flow condition in the preset operating test conditions and constructing the normalized characteristic curve based on the thermodynamic state parameters, the quantitative description of the choked flow critical point and the operating characteristics is established, so that the generated normalized characteristic curve can be used to effectively predict and analyze the refrigerating capacity and critical temperature of the double-condition refrigerating machine under the normalized choked flow condition. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1This is a schematic flowchart of the compressor performance prediction method provided in the embodiments of this application;

[0045] Figure 2 yes Figure 1 A flowchart illustrating step S102 in the process;

[0046] Figure 3 yes Figure 2 A flowchart illustrating step S201 in the process;

[0047] Figure 4 yes Figure 1 A flowchart illustrating step S103 in the process;

[0048] Figure 5 yes Figure 1 Another flowchart of step S103 in the process;

[0049] Figure 6 This is another schematic flowchart of the compressor performance prediction method provided in the embodiments of this application;

[0050] Figure 7 yes Figure 1 A flowchart illustrating step S104 in the process;

[0051] Figure 8 This is a schematic diagram of the characteristic curve of the flow coefficient changing with the evaporator temperature provided in the embodiments of this application;

[0052] Figure 9 This is a schematic diagram of the normalized characteristic relationship curve of the flow coefficient as a function of pressure ratio provided in the embodiments of this application;

[0053] Figure 10 This is a schematic diagram of the characteristic curve of the cooling capacity of the choked flow refrigeration mechanism as a function of evaporator temperature, provided in an embodiment of this application.

[0054] Figure 11 This is a schematic diagram of the normalized characteristic relationship curve of isentropic compression efficiency as a function of flow coefficient provided in the embodiments of this application;

[0055] Figure 12 This is another schematic flowchart of the compressor performance prediction method provided in the embodiments of this application;

[0056] Figure 13 This is a schematic diagram of the compressor performance prediction device provided in the embodiments of this application;

[0057] Figure 14 This is a schematic diagram of the hardware structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0058] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application and not to limit the present application.

[0059] It should be noted that, although the functional modules are divided in the device schematic diagram, and the logical order is shown in the flowchart, in some cases, the steps shown or described can be performed in a manner different from the module division in the device or the order in the flowchart. The terms "first", "second", and the like in the description and claims and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing the embodiments of the present application only, and is not intended to limit the present application.

[0061] As the core component of a centrifugal refrigeration unit, the performance characteristic curve of a centrifugal compressor is an important basis for compressor design, operation guidance, and fault diagnosis. Typically, the performance characteristic curve of a compressor needs to be obtained through specific bench testing in a production factory. However, in actual applications, the centrifugal compressor is part of a refrigeration unit, making it difficult for users to analyze the operating state of the refrigeration system based on the characteristics of the compressor itself.

[0062] In the prior art, when constructing the performance characteristic curve of a compressor, the volumetric flow rate or the refrigerant flow rate coefficient is usually used as the horizontal coordinate. These parameters are greatly affected by the inlet temperature, pressure of the compressor, and the type of refrigerant, making it difficult to evaluate the data measured under different operating conditions under the same standard, which makes it very difficult to design and analyze the performance of the compressor.

[0063] In addition, for a dual-condition refrigeration unit, it is normally operated in a choked flow condition. However, the prior art lacks analysis of the choked flow characteristics of a refrigeration compressor, there is no effective method to determine the choked flow critical point, and it is also impossible to predict the refrigeration capacity and critical temperature of the refrigeration compressor based on the choked flow characteristics, which limits the optimization and fault diagnosis of the internal operating parameters of the refrigeration compressor.

[0064] Therefore, how to quantitatively analyze the performance of the compressor and obtain more accurate evaluation data reflecting the performance of the compressor has become a technical problem to be solved.

[0065] Based on this, the embodiments of the present application provide a compressor performance prediction method and device, electronic equipment and storage medium, which are aimed at better quantitatively analyzing the performance of the compressor.

[0066] The compressor performance prediction method, device, electronic device, and storage medium provided in the embodiments of the present application are described in detail as follows. First, the compressor performance prediction method in the embodiments of the present application is described.

[0067] The compressor performance prediction method provided in the embodiments of the present application relates to the technical field of compressor control. The compressor performance prediction method provided in the embodiments of the present application can be applied to a terminal, can be applied to a server end, and can also be software running in the terminal or the server end. In some embodiments, the terminal can be a smart phone, a tablet computer, a notebook computer, a desktop computer, or the like; the server end can be configured as a stand-alone physical server, can be configured as a server cluster or a distributed system formed by multiple physical servers, or can be configured as a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDNs, and big data and artificial intelligence platforms; and the software can be an application that implements the compressor performance prediction method, but is not limited to the above forms.

[0068] The present application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld devices or portable devices, tablet devices, multi-processor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and the like. The present application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, and the like that perform specific tasks or implement specific abstract data types. The present application can also be practiced in a distributed computing environment in which tasks are performed by remote processing devices connected by a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media, including storage devices.

[0069] Figure 1 The method in the flowchart provided in the embodiments of the present application can include, but is not limited to, steps S101 to S104. Figure 1

[0070] In step S101, the thermodynamic state parameters of the target compressor under a plurality of preset operating test conditions are obtained; wherein the thermodynamic state parameters include operating parameters of the target compressor under a choked flow condition.

[0071] In step S102, a normalized flow coefficient corresponding to the target compressor is constructed based on the thermodynamic state parameters.

[0072] ​Step S103: Construct a characteristic relationship curve based on the normalized flow coefficient to obtain the normalized characteristic relationship curve;

[0073] Step S104: Obtain the target operating parameters of the target compressor under the target operating conditions, perform performance analysis based on the relationship curve between the target operating parameters and the normalized characteristic, and obtain the target performance information of the target compressor under the target operating conditions.

[0074] Steps S101 to S104 of this embodiment involve acquiring the thermodynamic state parameters of the target compressor under multiple preset operating test conditions. These thermodynamic state parameters include the operating parameters of the target compressor under congested flow conditions. A normalized flow coefficient corresponding to the target compressor is constructed based on these thermodynamic state parameters. A characteristic relationship curve is then constructed based on the normalized flow coefficient to obtain the normalized characteristic relationship curve. The target operating parameters of the target compressor under the target operating conditions are then obtained. Performance analysis is performed based on the target operating parameters and the normalized characteristic relationship curve to obtain the target performance information of the target compressor under the target operating conditions. Therefore, this application, by constructing a normalized flow coefficient, can eliminate or mathematically compensate for deviations caused by different inlet operating conditions, thereby establishing a universal evaluation standard independent of the inlet state. This makes the data measured under different operating conditions comparable, solving the problem of difficult compressor performance design and analysis. In addition, by incorporating the choked flow condition into the preset operating test conditions and constructing a normalized characteristic relationship curve based on thermodynamic state parameters, a quantitative description of the critical point and operating characteristics of the choked flow is established. Thus, the generated normalized characteristic relationship curve can be used to effectively predict and analyze the cooling capacity and critical temperature of the dual-condition refrigerator under normal choked flow conditions.

[0075] In step S101 of some embodiments, real-time operating data of the compressor needs to be collected by sensors under different operating conditions, such as changing the inlet guide vane opening, evaporator temperature, and condenser temperature. Thermodynamic state parameters include at least the evaporator saturation temperature, condenser saturation temperature, refrigeration capacity, compressor speed, and guide vane opening.

[0076] In particular, for dual-condition refrigerators, which normally operate in choked flow conditions, the operating test conditions need to cover the compressor's choked flow conditions in order to obtain key operating data under this condition, in order to make up for the lack of data collection on normal choked flow operation of dual-condition refrigerators in the existing technology.

[0077] In step S102 of some embodiments, a normalized flow coefficient corresponding to the target compressor is constructed based on thermodynamic state parameters, thereby unifying and normalizing the performance data measured under different inlet conditions so that it reflects the essential aerodynamic characteristics of the compressor.

[0078] Please see Figure 2 In some embodiments, the thermodynamic state parameters include at least the evaporator saturation temperature and the refrigeration capacity of the refrigeration unit, and step S102 may include, but is not limited to, steps S201 to S202:

[0079] Step S201: Obtain the refrigerant mass flow rate based on the cooling capacity of the refrigeration mechanism and the preset refrigerant thermophysical parameters;

[0080] Step S202: Construct a normalized flow coefficient based on the refrigerant mass flow rate and the evaporator saturation temperature; wherein, the normalized flow coefficient is used to eliminate the influence of the target compressor inlet state on the normalized characteristic relationship curve.

[0081] In step S201 of some embodiments, the refrigerant mass flow rate is obtained based on the cooling capacity of the refrigeration mechanism and preset refrigerant thermophysical parameters. This can be achieved through a heat balance calculation method, using the real-time acquired cooling capacity of the refrigeration mechanism as a known condition, and combining it with the energy changes of the refrigerant during the circulation process to infer the flow rate. The refrigerant thermophysical parameters used here refer to mathematical models or fitting equations that describe the physical properties (such as specific enthalpy, specific entropy, etc.) of the refrigerant at different temperatures and pressures.

[0082] During the calculation process, the measured evaporator saturation temperature and condenser saturation temperature are substituted into the refrigerant thermophysical parameter equation to calculate the refrigerant mass flow rate.

[0083] Please see Figure 3 In some embodiments, step S201 may include, but is not limited to, steps S301 to S304:

[0084] Step S301: Construct the thermal property equation of the refrigerant based on the refrigerant's thermal property parameters;

[0085] Step S302: Determine the inlet specific enthalpy of the guide vane based on the thermophysical property equation and the evaporator saturation temperature;

[0086] Step S303: Determine the specific enthalpy at the throttle valve inlet based on the thermophysical property equation and the condenser saturation temperature;

[0087] Step S304: Determine the refrigerant mass flow rate based on the ratio of the refrigeration capacity of the refrigeration mechanism to the inlet and outlet specific enthalpy difference.

[0088] In step S301 of some embodiments, a thermophysical equation for the refrigerant is constructed based on the refrigerant's thermophysical parameters. This process involves mathematically fitting the physical properties of a specific refrigerant within its commonly used operating temperature range (e.g., -10°C to 60°C) and pressure range. Functional relationships between saturation temperature and saturation pressure, saturated liquid specific enthalpy and saturation temperature, and saturated gaseous specific enthalpy and saturation temperature can be established by consulting relevant literature data. These fitted polynomial equations form the basis for subsequent calculations, enabling the control system to quickly and accurately calculate the corresponding thermodynamic state parameters based solely on measured temperature or pressure values, without needing to consult complex charts.

[0089] In step S302 of some embodiments, the inlet enthalpy of the guide vane is determined based on the thermophysical property equation and the evaporator saturation temperature. Considering the actual operating characteristics of centrifugal compressors for refrigeration, their suction superheat is usually very small (e.g., between 0°C and 3°C), so the effect of superheat on energy can be ignored. In this step, the measured evaporator saturation temperature is substituted into the thermophysical property equation for the saturated gaseous enthalpy constructed in step S301 to directly calculate the saturated gaseous enthalpy inside the evaporator, which is approximated as the inlet enthalpy of the guide vane and used to represent the energy state of the compressor suction port.

[0090] In step S303 of some embodiments, the enthalpy at the throttling valve inlet is determined based on the thermodynamic property equation and the condenser saturation temperature. In the context of calculating the refrigeration cycle flow rate, the enthalpy at the throttling valve inlet typically refers to the energy state at the condenser outlet, i.e., the throttling valve inlet. The measured condenser saturation temperature is substituted into the saturated liquid enthalpy thermodynamic property equation constructed in step S301 to calculate the saturated liquid enthalpy within the condenser. Since the process from the condenser to the throttling valve can be approximated as adiabatic with no pressure loss, this saturated liquid enthalpy represents the energy level of the high-pressure side liquid in the refrigeration cycle and is used as a deduction term when calculating the refrigeration capacity.

[0091] In step S304 of some embodiments, the refrigerant mass flow rate is determined based on the ratio of the refrigeration capacity of the refrigeration unit to the difference between the inlet and outlet specific enthalpy. According to the law of conservation of energy, the total refrigeration capacity of the refrigeration unit is equal to the refrigerant mass flow rate multiplied by the heat absorbed per unit mass of refrigerant in the evaporator (i.e., specific refrigeration capacity). In this step, the specific refrigeration capacity per unit is first obtained by subtracting the specific enthalpy at the inlet of the throttle valve (saturated liquid specific enthalpy) determined in step S303 from the specific enthalpy at the inlet of the guide vane determined in step S302; then, the current refrigerant mass flow rate is calculated by dividing the real-time collected refrigeration capacity of the refrigeration unit by this specific refrigeration capacity.

[0092] In some specific embodiments, the refrigerant mass flow rate (kg / s) can be measured using a thermal balance method to determine the refrigeration capacity of the refrigeration unit. Obtain, as shown in the following (1):

[0093] (1)

[0094] in, Indicates the refrigerant mass flow rate. To improve the cooling capacity of the refrigeration system, The specific refrigeration capacity per unit mass of refrigerant (kJ / kg) is obtained from the thermophysical properties of the refrigerant, where... It can be represented as follows (2):

[0095] (2)

[0096] Where h represents specific enthalpy (kJ / kg), subscripts g, gs, and ls represent superheated gaseous, saturated gaseous, and saturated liquid refrigerants, respectively, subscript IGVin represents the compressor inlet guide vane inlet, and throttlein represents the compressor throttle valve inlet.

[0097] Among them, the inlet enthalpy of the guide vane Approximately equal to the vapor phase saturation specific enthalpy of the evaporator The specific enthalpy at the throttle valve inlet is approximately Equal to the saturated specific enthalpy of the liquid phase in the condenser ,Right now:

[0098] (3)

[0099] (4)

[0100] In this context, the subscripts evap and cond represent the evaporator and condenser, respectively, and both saturated specific enthalpies can be obtained from the saturation temperatures of the evaporator and condenser, respectively.

[0101] According to formula (2), the specific enthalpy values ​​are subtracted to obtain the specific refrigeration capacity of the unit refrigerant. Then, the refrigeration capacity of the refrigeration machine is divided by the specific refrigeration capacity to accurately obtain the refrigerant mass flow rate under the current operating conditions.

[0102] In step S202 of some embodiments, the normalized flow coefficient is used to eliminate the influence of the target compressor inlet conditions on the normalized characteristic curve. Based on the similarity principle of centrifugal compressors, in order to obtain a universal characteristic curve that does not change with inlet conditions, such as inlet temperature fluctuations caused by seasonal variations, a dimensionless mass flow coefficient needs to be introduced.

[0103] Considering the characteristics of refrigeration systems, the compressor inlet stagnation pressure can be approximated as the evaporator saturation pressure, and the inlet stagnation temperature can be approximated as the evaporator saturation temperature. Since the saturation pressure is a single-valued function of the saturation temperature for a specific refrigerant, the normalized flow coefficient constructed in this step is defined as a specific functional relationship between the refrigerant mass flow rate and the evaporator saturation temperature; for example, the flow rate is directly proportional to the square root of the temperature and inversely proportional to the pressure. This construction method allows flow rate data at different evaporation temperatures to be converted to a unified benchmark, thereby eliminating the interference of inlet state parameters on the performance curve.

[0104] Based on the general theory of centrifugal compressors, and using similarity and performance curve normalization methods, a universal centrifugal compressor characteristic curve independent of the inlet condition can be established. The abscissa of this normalization typically uses the dimensionless mass flow coefficient. This represents the actual mass flow rate and the flow rate through a diameter at stagnation speed. The ratio of mass flow rate to channel flow rate, i.e.:

[0105] (5)

[0106] in, Indicates the refrigerant mass flow rate. The inlet stagnation density is the fluid density at which the airflow velocity at the compressor inlet stagnates to zero. This represents the speed of sound at the inlet stagnation temperature and pressure, which is the speed at which sound travels through the gas. The diameter of the impeller tip. Other parameters for the refrigerant, It is the isentropic compression factor. To alleviate import stagnation pressure, This refers to the stagnation temperature at the import port.

[0107] By employing a dimensionless mass flow coefficient, performance data measured under different inlet conditions can be unified onto a single curve, eliminating the influence of inlet conditions on the performance curve. Furthermore, the Mach number similarity criterion is considered, significantly simplifying the compressor design, analysis, and application process. Inlet conditions include inlet temperature, inlet pressure, and gas type. For centrifugal compressors used in refrigeration, the evaporator temperature can vary from -8℃ to 14℃, resulting in significant variations in compressor inlet temperature. Additionally, different refrigerants, such as R134a and R1233zd, can be used, leading to a wide range of inlet condition variations. Using this dimensionless mass flow coefficient, the characteristic curves of centrifugal compressors with different refrigeration temperatures and refrigerant types can be normalized.

[0108] However, for centrifugal compressors used in refrigeration, the dimensionless mass flow coefficient... For the same model of centrifugal compressor, the impeller size With a fixed refrigerant and isentropic compressibility coefficient, With gas constant Since it is also fixed, the above formula (5) can be simplified to the following formula (6) to represent the horizontal axis of the compressor characteristic curve:

[0109] (6)

[0110] On the other hand, stagnation inspiratory pressure This can be considered as the evaporator saturation pressure. ,Right now And the stagnation inhalation temperature It can be represented as That is, the saturation temperature of the evaporator With superheat The sum, considering that the superheat is between 0 and 3°C, mostly close to 0, therefore Therefore, formula (7) can be obtained from formula (6):

[0111] (7)

[0112] evaporator saturation temperature It is the saturation temperature of the evaporator. The two are functions of the same principle, and they are interrelated; different refrigerants have different saturation pressures. The curve showing the relationship with saturation temperature, i.e. The subscript 's' indicates saturation; therefore, the normalized flow coefficient of a centrifugal compressor used for refrigeration is called the refrigerant mass flow rate. and evaporator saturation temperature The function is as follows (8):

[0113] (8)

[0114] Through steps S201 to S202, this embodiment of the application can utilize easily measurable temperature and cooling capacity data in engineering to obtain core flow parameters through indirect calculation, avoiding the need to install expensive and complex direct flow meters. More importantly, by constructing a normalized flow coefficient, it successfully solves the problem in the prior art where the characteristic curve diverges with changes in inlet temperature and pressure when using volumetric flow rate as the abscissa. This processing method allows performance data under different operating conditions to converge to the same normalized curve, providing a universal data foundation for unified calibration of compressor performance, accurate identification of choked flow critical points, and subsequent performance prediction.

[0115] In step S103 of some embodiments, a characteristic relationship curve is constructed based on the normalized flow coefficient to obtain a normalized characteristic relationship curve. This step involves plotting the normalized characteristic relationship curve under different guide vane openings by using the calculated normalized flow coefficient as the abscissa and the pressure ratio calculated based on the condenser pressure and evaporator pressure as the ordinate.

[0116] Please see Figure 4 In some embodiments, step S103 may include, but is not limited to, steps S401 to S403:

[0117] Step S401: Obtain the evaporator pressure and condenser pressure;

[0118] Step S402: Based on the evaporator pressure and condenser pressure, obtain the compressor pressure ratio;

[0119] Step S403: Construct the normalized characteristic relationship curve of the corresponding target compressor based on the compressor pressure ratio and normalized flow coefficient.

[0120] In step S401 of some embodiments, the evaporator pressure and condenser pressure are acquired. This data can be acquired in two ways: first, by directly measuring the real-time pressure data of the evaporator and condenser using pressure sensors installed on the refrigeration unit; second, by indirectly acquiring the data based on the thermodynamic properties of the refrigerant, i.e., by measuring the evaporator saturation temperature and condenser saturation temperature using temperature sensors, and calculating the corresponding saturation pressure using a pre-constructed functional relationship between refrigerant saturation pressure and saturation temperature, such as a polynomial fitting equation. In engineering approximation, the evaporator pressure can be considered as the compressor inlet stagnation pressure, and the condenser pressure can be considered as the compressor outlet stagnation pressure.

[0121] In step S402 of some embodiments, the compressor pressure ratio is obtained based on the evaporator pressure and condenser pressure. The compressor pressure ratio is a key indicator for measuring the compressor's performance characteristics, defined as the ratio of discharge pressure to suction pressure. In this step, the condenser pressure obtained in step S401 is used as the numerator, and the evaporator pressure as the denominator, to calculate the ratio of the two to obtain the actual pressure ratio under the current operating conditions. The compressor pressure ratio reflects the compressor's ability to increase the refrigerant pressure level under the current evaporation and condensation conditions.

[0122] In step S403 of some embodiments, a normalized characteristic curve for the target compressor is constructed based on the compressor pressure ratio and the normalized flow coefficient. Data points are plotted in a two-dimensional coordinate system with the normalized flow coefficient calculated in step S102 as the abscissa and the compressor pressure ratio calculated in step S402 as the ordinate. Since compressor performance is affected by the inlet guide vane opening, data is typically collected at different guide vane openings to generate a set of normalized characteristic curves corresponding to different guide vane openings.

[0123] Through steps S401 to S403, this embodiment of the application establishes a standardized method for characterizing compressor performance. By converting physical pressure into a dimensionless pressure ratio and combining it with the aforementioned normalized flow coefficient, a universal normalized characteristic relationship curve decoupled from specific inlet operating conditions is successfully constructed. This not only makes operating data under different seasons and operating conditions comparable, but more importantly, the normalized characteristic relationship curve intuitively displays the compressor's operating boundaries, helping technicians quickly identify key performance characteristics such as the choke point, providing a visual model basis for subsequent accurate performance prediction and control optimization of the refrigeration unit under complex operating conditions.

[0124] See Figure 5 In other embodiments, step S103 may also include, but is not limited to, steps S501 to S502:

[0125] Step S501: Based on the thermodynamic state parameters and the thermophysical property equation of the refrigerant, the single-stage isentropic compression efficiency is calculated.

[0126] Step S502: Construct a normalized characteristic relationship curve of isentropic compression efficiency as a function of normalized flow coefficient based on single-stage isentropic compression efficiency.

[0127] In step S501 of some embodiments, the single-stage isentropic compression efficiency is calculated based on thermodynamic state parameters and the refrigerant's thermophysical property equations. This calculation process aims to measure the compressor's ability to convert energy into effective compression work. Specifically, based on the collected inlet guide vane inlet state (approximately evaporator state) and the collected diffuser outlet state (approximately condenser state), combined with the refrigerant's entropy calculation formula, the ideal outlet specific enthalpy is determined when the entropy value remains constant during the compression process. The isentropic compression work is calculated using the difference between this ideal outlet specific enthalpy and the inlet specific enthalpy. Simultaneously, the actual compression work is calculated based on actual measured temperature or power data. The ratio of the isentropic compression work to the actual compression work is defined as the single-stage isentropic compression efficiency. This step utilizes a high-precision thermophysical property fitting equation, ensuring that the compressor's internal efficiency can be accurately calculated using conventional thermodynamic parameters even in the absence of expensive torque meters.

[0128] In step S502 of some embodiments, a normalized characteristic curve showing the isentropic compression efficiency as a function of the normalized flow coefficient is constructed based on the single-stage isentropic compression efficiency. The normalized flow coefficient, calculated previously, is plotted on the x-axis, and the single-stage isentropic compression efficiency calculated in step S501 is plotted on the y-axis. This visually reflects the compressor's energy efficiency performance under different operating conditions. Especially in the congested flow region, although the flow coefficient remains constant, the normalized characteristic curve shows a sharp decrease in isentropic compression efficiency as the pressure ratio decreases. This visualized or modeled curve relationship reveals the energy efficiency cost of the compressor operating under extreme conditions.

[0129] Through steps S501 to S502, this embodiment of the application constructs a two-dimensional evaluation system that includes pressure ratio and energy efficiency. The pressure ratio characteristic curve marks the physical operating boundary of the machine, such as the critical point of congested flow, solving the problem of lack of operational guidance for dual-condition units under extreme conditions. The efficiency characteristic curve further quantifies the economic cost under extreme conditions. Constructing these two types of normalized characteristic relationship curves can ensure the cooling flow demand while taking into account the operating efficiency, thereby achieving global optimization control of the refrigeration system in complex variable operating conditions.

[0130] In step S104 of some embodiments, the target operating parameters of the target compressor under the target operating condition are obtained. Performance analysis is performed based on the relationship curve between the target operating parameters and the normalized characteristic curve to obtain the target performance information of the target compressor under the target operating condition. In actual operation, the current operating parameters of the target compressor, such as the current evaporation pressure and condensation pressure, are collected in real time. By comparing the real-time compressor pressure ratio with the normalized characteristic relationship curve determined in step S103, it can be determined whether the compressor is currently operating in a choked flow condition. If it is in a choked flow condition, the calibrated choked flow coefficient is directly used for soft measurement to reverse calculate the current refrigerant mass flow rate and cooling capacity as target performance information, thereby realizing real-time quantitative analysis and prediction of compressor performance.

[0131] Please see Figure 6 In some embodiments, the embodiments of this application may also include, but are not limited to, steps S601 to S602:

[0132] Step S601: Identify the region in the normalized characteristic relationship curve where the normalized flow coefficient remains constant as the compressor pressure ratio decreases, and determine it as the choked flow condition region.

[0133] Step S602: The normalized flow coefficient corresponding to the choked flow condition zone is determined as the choked flow flow coefficient, and the compressor pressure ratio entering the choked flow condition zone is determined as the choked flow critical pressure ratio.

[0134] In step S601 of some embodiments, the region in the normalized characteristic curve where the normalized flow coefficient remains constant as the compressor pressure ratio decreases is identified and determined as the choked flow operating region. Specifically, trend analysis is performed on the plotted normalized characteristic curve, with particular attention paid to the low pressure ratio region. With a fixed inlet guide vane opening, when it is observed that as the compressor pressure ratio on the vertical axis decreases, the normalized flow coefficient on the horizontal axis no longer changes significantly, but instead presents a vertical or nearly vertical straight line segment, the operating range corresponding to this straight line segment is determined to be the compressor having entered its physical limit state, i.e., the choked flow operating region. This indicates that the airflow has reached the speed of sound at the throat of the flow channel, and the flow rate cannot continue to increase as the back pressure decreases.

[0135] In step S602 of some embodiments, the normalized flow coefficient corresponding to the choked flow operating region is determined as the choked flow flow coefficient, and the compressor pressure ratio entering the choked flow operating region is determined as the choked flow critical pressure ratio. In this step, the horizontal axis value corresponding to the constant region is read and fixed as the choked flow flow coefficient, serving as a known constant in subsequent calculations. Simultaneously, the inflection point in the normalized characteristic relationship curve transitioning from the slope variation region to the constant value region is found, and the vertical axis value corresponding to this inflection point is read and defined as the choked flow critical pressure ratio. These two parameters together constitute the digital calibration of the choked flow characteristics, where the choked flow flow coefficient represents the maximum flow capacity at the current guide vane opening, and the choked flow critical pressure ratio defines the pressure boundary between normal operation and choked flow operation.

[0136] Through steps S601 to S602, this application provides an effective method for extracting key characteristic parameters of choked flow from routine operating data. This process simplifies the complex choked flow condition into two quantifiable engineering parameters: a fixed normalized flow coefficient and a critical pressure ratio. This not only fills the gap in the prior art regarding the lack of analytical methods for dual-condition refrigerators under normal choked flow conditions, but also provides the necessary model foundation for subsequent simplified cooling capacity prediction and critical temperature early warning based on these fixed parameters. This enables rapid evaluation of compressor performance under extreme conditions without complex iterative calculations.

[0137] Please see Figure 7 In some embodiments, step S104 may include, but is not limited to, steps S701 to S703:

[0138] Step S701: Perform performance analysis based on the relationship curve between the target operating parameters and the normalized characteristic curve;

[0139] Step S702: When the analysis determines that the target compressor is in the blocked flow operating region, the blocked flow coefficient is used as a fixed input, and the currently measured evaporator saturation temperature is determined according to the target operating parameters, and the corresponding refrigerant mass flow rate is calculated in reverse.

[0140] Step S703: Based on the currently measured inlet and outlet enthalpy difference, calculate the predicted cooling capacity to evaluate the target performance information of the refrigerator under choked flow conditions.

[0141] In step S701 of some embodiments, performance analysis is performed based on the target operating parameters and the normalized characteristic curve. This step mainly involves mapping the real-time collected target compressor operating data to a pre-constructed mathematical model. The current condensing and evaporating pressures are obtained, and the real-time compressor pressure ratio is calculated. Simultaneously, the corresponding normalized characteristic curve is selected based on the current inlet guide vane opening. The real-time compressor pressure ratio is compared with the normalized characteristic curve to determine whether the current operating point is located in the slope variation region of the curve (i.e., the normal adjustment region) or in the vertical region with a constant flow coefficient (i.e., the choked flow region). This determination process forms the basis for subsequent selection of calculation logic, ensuring accurate identification of the compressor's current aerodynamic state.

[0142] In step S702 of some embodiments, when the analysis determines that the target compressor is in a choked flow operating condition, the choked flow coefficient is used as a fixed input, and the currently measured evaporator saturation temperature is determined based on the target operating parameters. The corresponding refrigerant mass flow rate is then calculated in reverse. Once it is confirmed that the compressor has entered a choked flow state, for example, when the real-time compressor pressure ratio is lower than the critical pressure ratio for choked flow, the normalized flow coefficient is no longer considered a variable that changes with the pressure ratio, but is locked as a pre-calibrated choked flow coefficient constant. Using the definition formula of the normalized flow coefficient, the known choked flow coefficient constant and the real-time measured evaporator saturation temperature are substituted into the formula to obtain a known solution to the equation, and the refrigerant mass flow rate under the current operating condition is calculated in reverse.

[0143] In step S703 of some embodiments, the predicted cooling capacity is calculated based on the currently measured inlet and outlet enthalpy difference, thereby evaluating the target performance information of the chiller under congested flow conditions. After obtaining the refrigerant mass flow rate, the specific enthalpy difference between the evaporator outlet and the condenser outlet, calculated using the real-time temperature-based thermodynamic property equation, is multiplied to obtain the current predicted cooling capacity. Since the dual-condition chiller normally operates in the congested flow region under air conditioning conditions, this step achieves soft measurement of the actual cooling capacity of the chiller without relying on physical flow meters. The calculated cooling capacity data can be further used for real-time evaluation of the energy efficiency ratio or as a feedback signal for system load adjustment, thus serving as the target performance information of the chiller under congested flow conditions.

[0144] Through steps S701 to S703, this embodiment cleverly utilizes the physical characteristic of a centrifugal compressor having a constant flow coefficient under choked flow conditions, simplifying complex nonlinear fluid calculations into algebraic operations based on fixed constants. This method is particularly suitable for dual-condition units, solving the problem of existing technologies being unable to accurately obtain refrigeration unit performance data under normal choked flow conditions. It not only enables real-time online prediction of refrigeration capacity at low cost but also clearly identifies whether the machine is in a choked flow state, thus providing precise quantitative evidence for optimized control and energy efficiency management of the refrigeration system.

[0145] In some specific embodiments, for the operating data of a dual-condition refrigeration fixed-frequency centrifugal compressor, the operating data at different condenser temperatures are classified to obtain the changes in flow coefficient and pressure ratio with evaporator temperature at the same condenser temperature, such as... Figure 8 The data shown is the test data when the guide vane opening is IGV=100%.

[0146] With condenser temperature T s,cond Taking 35℃ as an example, the flow coefficient changes differently as the evaporator temperature decreases. When the pressure ratio is less than 3.5, corresponding to the right side of point Ap35, the flow coefficient is close to a constant. When the pressure ratio is greater than 3.5, corresponding to the left side of point Ap35, the flow coefficient gradually decreases. This shows that point Ap35 is the critical pressure ratio for choked flow, and point Ap35 is the point where the flow coefficient changes accordingly. Interestingly, for different condenser temperatures, the critical pressure ratio for choked flow is close to 3.5, for example, points Ap33 and Ap37 correspond to condenser temperatures of 33℃ and 37℃ respectively; while the flow coefficient for choked flow at different condenser temperatures is basically the same, a constant of approximately 2.7. As the condenser temperature decreases, the evaporator temperature corresponding to the critical point for choked flow decreases. When the condenser temperature is 31℃, the compressor operates in choked flow mode at temperatures above the design evaporator temperature range of -6.2℃. Based on the same critical pressure ratio, the critical temperature for choked flow at the corresponding condenser temperature can be predicted. Figure 8 The test data can be used to further obtain the normalized characteristic curve of the compressor, and to determine the critical point of choke flow.

[0147] according to Figure 8 By analyzing the flow coefficient and pressure ratio data, the characteristic curve (pressure ratio ~ flow coefficient) of the centrifugal compressor under the condition of IGV=100% guide vane opening was obtained. Measurements were then taken at different guide vane openings to obtain the characteristic curves of the fixed-frequency centrifugal compressor for different guide vane openings, as shown below. Figure 9As shown, for the guide vane opening IGV=100% condition, the pressure ratio versus flow coefficient curve is independent of evaporator temperature, condenser temperature, etc., indicating that the flow coefficient used in this invention can meet the requirement of characteristic curve normalization. For the pressure ratio curve below the choked flow boundary, although the pressure ratio continuously decreases, the choked flow coefficient remains unchanged, close to 2.7, which is consistent with... Figure 8 The data is consistent with the Chinese data.

[0148] Based on actual operating data from dual-condition refrigeration units, a large number of operating points are under congested flow conditions. This is related to the fact that dual-condition compressors are designed with ice-making conditions as their operating point, such as an evaporator temperature of -6.2℃ and a condenser temperature of 35℃. When the evaporator temperature increases to -4℃, the compressor experiences congested flow. For dual-condition refrigeration units with the same condenser temperature, the operating condition when the evaporator temperature is above -4℃ is basically under congested flow conditions. This shows that congested flow operation is the norm for dual-condition refrigeration units.

[0149] Above the choked flow boundary is the pressure ratio characteristic curve corresponding to the guide vane opening degree. As the pressure ratio increases, the flow coefficient decreases. For the guide vane opening degree IGV=100%, the critical pressure ratio for choked flow is 3.5. For other guide vane opening degrees, the trend of the pressure ratio characteristic curve is consistent with the guide vane opening degree IGV=100% condition; the difference is that as the guide vane opening degree decreases, the critical pressure ratio for choked flow decreases, and the flow coefficient for choked flow also decreases.

[0150] Based on actual operation, dual-mode refrigeration units typically operate in choked flow mode. For refrigeration compressors whose compressor pressure ratio characteristic curve and choked flow characteristics are known, such as those with known... Figure 9 The characteristic curve with IGV=100% indicates that the evaporator operates in choked flow mode at a condenser temperature of 35℃ and an evaporator temperature greater than -4℃, where the choked flow coefficient is 2.7. Figure 9 By fitting the pressure ratio characteristic curve at 100% IGV, we can obtain:

[0151] (9)

[0152] Among them, the fitting coefficient , , It is known. It is the intake pressure, which can be approximated as the steam turbine pressure. , It is the exhaust pressure, which can be approximated as the condenser pressure. , This represents the compressor pressure ratio. From this, the mass flow rate of the refrigeration unit can be calculated, and by obtaining the specific refrigeration capacity, the cooling capacity of the refrigeration unit can be predicted. .

[0153] Different evaporator and condenser temperatures can yield different mass flow rates and specific refrigeration capacities of the chiller. This allows us to obtain the cooling capacity at different condenser temperatures. With changes in evaporator temperature, such as Figure 10 As shown. Under operating conditions with known evaporator and condenser temperatures, the cooling capacity of the refrigeration system can be predicted. As shown in the figure, as the evaporator temperature increases, the compressor transitions from normal flow to choked flow, resulting in a critical change in cooling capacity—the choked flow critical point. From this critical point, the compressor operates in choked flow mode as the evaporator temperature increases, exhibiting a linear cooling capacity trend. This allows for the prediction of the cooling capacity of a dual-condition air conditioning unit at different cooling temperatures.

[0154] In some specific embodiments, corresponding Figure 9 , Figure 11 The normalized characteristic curve of the isentropic compression efficiency of the centrifugal compressor as a function of the flow coefficient is shown. Figure 11 The data shows that when the guide vane opening is large, the isentropic compression efficiency is relatively high and remains relatively stable above the congested flow boundary. However, below the congested flow boundary, the isentropic compression efficiency drops sharply, indicating that congested flow operation is not conducive to improving the energy efficiency of the refrigeration unit. In reality, to simplify operation control and obtain sufficient cooling capacity or flow coefficient, the compressor needs to operate in congested flow, thus sacrificing some energy efficiency.

[0155] Please see Figure 12 In some embodiments, the embodiments of this application may also include, but are not limited to, steps S801 to S804:

[0156] Step S801: Obtain the real-time normalized flow coefficient under the target operating condition based on the target operating parameters;

[0157] Step S802: In the normalized characteristic relationship curve, find the theoretical isentropic compression efficiency corresponding to the real-time normalized flow coefficient.

[0158] Step S803: Obtain the real-time isentropic compression efficiency under the target operating condition;

[0159] Step S804: Based on the real-time isentropic compression efficiency and the theoretical isentropic compression efficiency, perform energy efficiency assessment and generate energy efficiency assessment information.

[0160] In step S801 of some embodiments, the real-time normalized flow coefficient under the target operating condition is obtained based on the target operating parameters. During the actual operation of the compressor, the control system collects target operating parameters in real time, including the refrigeration capacity of the refrigeration unit and the evaporator saturation temperature. Using the normalized flow coefficient calculation method determined in the aforementioned steps, the real-time normalized flow coefficient reflecting the current aerodynamic load state is calculated. The real-time normalized flow coefficient eliminates the influence of inlet state fluctuations and can be used as a reference coordinate for indexing and searching in the standardized characteristic curve.

[0161] In step S802 of some embodiments, the theoretical isentropic compression efficiency corresponding to the real-time normalized flow coefficient is found in the normalized characteristic relationship curve. Using the obtained real-time normalized flow coefficient as the horizontal axis index value, a mapping search is performed in the pre-constructed normalized characteristic relationship curve showing the change of isentropic compression efficiency with the flow coefficient. The corresponding vertical axis value on the curve is read, which is the theoretical isentropic compression efficiency under the current operating condition. The theoretical isentropic compression efficiency represents the standard energy efficiency level that the compressor should possess under the design state or healthy baseline state at this flow load.

[0162] In step S803 of some embodiments, the real-time isentropic compression efficiency under the target operating condition is obtained. This is achieved through real-time thermodynamic calculations. Based on the inlet and outlet temperature and pressure data collected in real time by sensors, and combined with the refrigerant thermophysical property equation, the current isentropic compression work and the actual compression work corresponding to the actual enthalpy difference are calculated respectively. The ratio of the two is the real-time isentropic compression efficiency under the target operating condition. The real-time isentropic compression efficiency reflects the compressor's true energy conversion efficiency at the current moment, including the actual impact of factors such as equipment wear, fouling, or non-optimal control.

[0163] In step S804 of some embodiments, an energy efficiency assessment is performed based on the real-time isentropic compression efficiency and the theoretical isentropic compression efficiency to generate energy efficiency assessment information. The actual efficiency calculated in real-time is compared and analyzed with the theoretical benchmark efficiency obtained from a lookup table to generate energy efficiency assessment information. For example, the deviation between the two is calculated; if the real-time efficiency is significantly lower than the theoretical efficiency, or the deviation exceeds a preset tolerance threshold, energy efficiency assessment information is generated. The generated energy efficiency assessment information may include energy efficiency degradation warnings, potential mechanical failure warnings, or optimization suggestions for control strategies.

[0164] Through steps S801 to S804, not only can the compressor's operating energy efficiency be quantified in real time, but more importantly, it provides a dynamic theoretical benchmark that matches the operating conditions using a normalized characteristic curve. This overcomes the limitations of traditional methods that rely solely on a single fixed value to determine energy efficiency, enabling the system to distinguish between normal efficiency fluctuations caused by changes in operating conditions and abnormal declines due to equipment performance degradation. This provides valuable decision-making support for predictive maintenance and refined energy-saving control of refrigeration units.

[0165] In some specific embodiments, based on the different locations of the input power boundary, the isentropic compression efficiency can be divided into the compressor unit isentropic compression efficiency and the compressor isentropic compression efficiency. The former refers to the electrical work at the input end of the variable frequency starter cabinet, while the latter refers to the mechanical work output by the compressor bearing.

[0166] This application's embodiments acquire the thermodynamic state parameters of the target compressor under multiple preset operating test conditions. These thermodynamic state parameters include the operating parameters of the target compressor under congested flow conditions. Based on these thermodynamic state parameters, a normalized flow coefficient corresponding to the target compressor is constructed. Based on the normalized flow coefficient, a characteristic relationship curve is constructed, resulting in a normalized characteristic relationship curve. The target operating parameters of the target compressor under the target operating conditions are then obtained. Performance analysis is performed based on the target operating parameters and the normalized characteristic relationship curve to obtain the target performance information of the target compressor under the target operating conditions. Therefore, this application, by constructing a normalized flow coefficient, can eliminate or mathematically compensate for deviations caused by different inlet operating conditions, thereby establishing a universal evaluation standard independent of inlet conditions. This makes the data measured under different operating conditions comparable, solving the problem of difficult compressor performance design and analysis. In addition, by incorporating the choked flow condition into the preset operating test conditions and constructing a normalized characteristic relationship curve based on thermodynamic state parameters, a quantitative description of the critical point and operating characteristics of the choked flow is established. Thus, the generated normalized characteristic relationship curve can be used to effectively predict and analyze the cooling capacity and critical temperature of the dual-condition refrigerator under normal choked flow conditions.

[0167] Please see Figure 13 This application also provides a compressor performance prediction device that can implement the above-described compressor performance prediction method. The device includes:

[0168] The data acquisition module is used to acquire the thermodynamic state parameters of the target compressor under multiple preset operating test conditions; among which, the thermodynamic state parameters include the operating parameters of the target compressor under choked flow conditions;

[0169] The flow coefficient construction module is used to construct the normalized flow coefficient corresponding to the target compressor based on thermodynamic state parameters;

[0170] The normalized characteristic curve construction module is used to construct characteristic curves based on normalized flow coefficients, thereby obtaining normalized characteristic curves.

[0171] The performance prediction module is used to obtain the target operating parameters of the target compressor under the target operating conditions, and to perform performance analysis based on the relationship curve between the target operating parameters and the normalized characteristic to obtain the target performance information of the target compressor under the target operating conditions.

[0172] The specific implementation of the compressor performance prediction device is basically the same as the specific embodiment of the compressor performance prediction method described above, and will not be repeated here.

[0173] This application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the above-described compressor performance prediction method. This electronic device can be any smart terminal, including tablet computers, in-vehicle computers, etc.

[0174] Please see Figure 14 , Figure 14 The hardware structure of an electronic device according to another embodiment is illustrated. The electronic device includes:

[0175] The processor 1401 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this application.

[0176] The memory 1402 can be implemented as a read-only memory (ROM), static storage device, dynamic storage device, or random access memory (RAM). The memory 1402 can store the operating system and other applications. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 1402 and is called and executed by the processor 1401 using the compressor performance prediction method of the embodiments of this application.

[0177] The input / output interface 1403 is used to implement information input and output;

[0178] The communication interface 1404 is used to enable communication and interaction between this device and other devices. Communication can be achieved through wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0179] Bus 1405 transmits information between various components of the device (e.g., processor 1401, memory 1402, input / output interface 1403, and communication interface 1404);

[0180] The processor 1401, memory 1402, input / output interface 1403 and communication interface 1404 are connected to each other within the device via bus 1405.

[0181] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described compressor performance prediction method.

[0182] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0183] The compressor performance prediction method, apparatus, electronic device, and storage medium provided in this application acquire thermodynamic state parameters of a target compressor under multiple preset operating test conditions. These thermodynamic state parameters include the operating parameters of the target compressor under congested flow conditions. Based on these thermodynamic state parameters, a normalized flow coefficient corresponding to the target compressor is constructed. Based on the normalized flow coefficient, a characteristic relationship curve is constructed, resulting in a normalized characteristic relationship curve. The target operating parameters of the target compressor under the target operating conditions are then obtained. Performance analysis is performed based on the target operating parameters and the normalized characteristic relationship curve to obtain the target performance information of the target compressor under the target operating conditions. Therefore, this application, by constructing a normalized flow coefficient, can eliminate or mathematically compensate for deviations caused by different inlet operating conditions, thereby establishing a universal evaluation standard independent of the inlet state. This makes the data measured under different operating conditions comparable, solving the problem of difficult compressor performance design and analysis. In addition, by incorporating the choked flow condition into the preset operating test conditions and constructing a normalized characteristic relationship curve based on thermodynamic state parameters, a quantitative description of the critical point and operating characteristics of the choked flow is established. Thus, the generated normalized characteristic relationship curve can be used to effectively predict and analyze the cooling capacity and critical temperature of the dual-condition refrigerator under normal choked flow conditions.

[0184] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0185] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.

[0186] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0187] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0188] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0189] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: 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.

[0190] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. The coupling or direct coupling or communication connection between the shown or discussed units may be through some interfaces, or indirect coupling or communication connection between the apparatus or units, and may be electrical, mechanical, or other forms.

[0191] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0192] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0193] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0194] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A method for predicting compressor performance, characterized in that, The method includes: Acquire the thermodynamic state parameters of the target compressor under multiple preset operating test conditions; wherein, the thermodynamic state parameters include the operating parameters of the target compressor under choked flow conditions; Based on the thermodynamic state parameters, a normalized flow coefficient corresponding to the target compressor is constructed; Based on the normalized flow coefficient, a characteristic relationship curve is constructed to obtain the normalized characteristic relationship curve; Obtain the target operating parameters of the target compressor under the target operating conditions, and perform performance analysis based on the relationship curve between the target operating parameters and the normalized characteristic to obtain the target performance information of the target compressor under the target operating conditions; The thermodynamic state parameters include at least the evaporator saturation temperature and the refrigeration capacity of the refrigeration unit. The step of constructing a normalized flow coefficient corresponding to the target compressor based on the thermodynamic state parameters includes: obtaining the refrigerant mass flow rate based on the refrigeration capacity and preset refrigerant thermophysical parameters; and constructing a normalized flow coefficient based on the refrigerant mass flow rate and the evaporator saturation temperature. The normalized flow coefficient is used to eliminate the influence of the target compressor inlet state on the normalized characteristic relationship curve. The thermodynamic state parameters also include the condenser saturation temperature. The process of obtaining the refrigerant mass flow rate based on the refrigeration capacity of the refrigeration unit and preset refrigerant thermophysical parameters includes: constructing a thermophysical property equation for the refrigerant based on the refrigerant thermophysical parameters; determining the inlet specific enthalpy of the inlet guide vane based on the thermophysical property equation and the evaporator saturation temperature; determining the inlet specific enthalpy of the throttle valve based on the thermophysical property equation and the condenser saturation temperature; and determining the refrigerant mass flow rate based on the ratio of the refrigeration capacity of the refrigeration unit to the difference between the inlet and outlet specific enthalpies. The step of constructing a characteristic relationship curve based on the normalized flow coefficient to obtain a normalized characteristic relationship curve includes: obtaining the evaporator pressure and condenser pressure; obtaining the compressor pressure ratio based on the evaporator pressure and the condenser pressure; constructing the normalized characteristic relationship curve of the corresponding target compressor based on the compressor pressure ratio and the normalized flow coefficient; and / or, calculating the single-stage isentropic compression efficiency based on the thermodynamic state parameters and the refrigerant's thermophysical property equation; and constructing the normalized characteristic relationship curve of the isentropic compression efficiency as a function of the normalized flow coefficient based on the single-stage isentropic compression efficiency. The performance analysis based on the target operating parameters and the normalized characteristic curve to obtain the target performance information of the target compressor under the target operating conditions includes: performing performance analysis based on the target operating parameters and the normalized characteristic curve; when the analysis determines that the target compressor is in the choked flow operating region, using the choked flow coefficient as a fixed input, determining the currently measured evaporator saturation temperature according to the target operating parameters, and back-calculating the corresponding refrigerant mass flow rate; calculating the predicted cooling capacity based on the currently measured inlet and outlet enthalpy difference, thereby evaluating the target performance information of the refrigeration unit under the choked flow operating conditions.

2. The method according to claim 1, characterized in that, The method further includes: Identify the region in the normalized characteristic curve where the normalized flow coefficient remains constant as the compressor pressure ratio decreases, and determine it as the choked flow operating region; The normalized flow coefficient corresponding to the choked flow condition zone is determined as the choked flow flow coefficient, and the compressor pressure ratio entering the choked flow condition zone is determined as the choked flow critical pressure ratio.

3. The method according to claim 1, characterized in that, The method further includes: Based on the target operating parameters, the real-time normalized flow coefficient under the target operating condition is obtained; In the normalized characteristic relationship curve, find the theoretical isentropic compression efficiency corresponding to the real-time normalized flow coefficient; Obtain the real-time isentropic compression efficiency under the target operating condition; Energy efficiency assessment is performed based on the real-time isentropic compression efficiency and the theoretical isentropic compression efficiency to generate energy efficiency assessment information.

4. A compressor performance prediction device, characterized in that, The device includes: The data acquisition module is used to acquire the thermodynamic state parameters of the target compressor under multiple preset operating test conditions; wherein, the thermodynamic state parameters include the operating parameters of the target compressor under choked flow conditions; A flow coefficient construction module is used to construct a normalized flow coefficient corresponding to the target compressor based on the thermodynamic state parameters; wherein, the thermodynamic state parameters include at least the evaporator saturation temperature and the refrigeration capacity of the refrigeration unit, and the construction of the normalized flow coefficient corresponding to the target compressor based on the thermodynamic state parameters includes: obtaining the refrigerant mass flow rate based on the refrigeration capacity of the refrigeration unit and preset refrigerant thermophysical parameters; constructing a normalized flow coefficient based on the refrigerant mass flow rate and the evaporator saturation temperature; wherein, the normalized flow coefficient is used to eliminate the influence of the target compressor inlet state on the normalized characteristic relationship curve; The thermodynamic state parameters also include the condenser saturation temperature. The process of obtaining the refrigerant mass flow rate based on the refrigeration capacity of the refrigeration unit and preset refrigerant thermophysical parameters includes: constructing a thermophysical property equation for the refrigerant based on the refrigerant thermophysical parameters; determining the inlet specific enthalpy of the inlet guide vane based on the thermophysical property equation and the evaporator saturation temperature; determining the inlet specific enthalpy of the throttle valve based on the thermophysical property equation and the condenser saturation temperature; and determining the refrigerant mass flow rate based on the ratio of the refrigeration capacity of the refrigeration unit to the difference between the inlet and outlet specific enthalpies. A normalized characteristic curve construction module is used to construct a characteristic curve based on the normalized flow coefficient, thereby obtaining a normalized characteristic curve. The construction of the characteristic curve based on the normalized flow coefficient includes: obtaining the evaporator pressure and condenser pressure; obtaining the compressor pressure ratio based on the evaporator pressure and condenser pressure; constructing the normalized characteristic curve for the corresponding target compressor based on the compressor pressure ratio and the normalized flow coefficient; and / or calculating the single-stage isentropic compression efficiency based on the thermodynamic state parameters and the refrigerant's thermophysical property equation; and constructing the normalized characteristic curve showing the isentropic compression efficiency as a function of the normalized flow coefficient based on the single-stage isentropic compression efficiency. The performance prediction module is used to acquire the target operating parameters of the target compressor under the target operating conditions, and perform performance analysis based on the target operating parameters and the normalized characteristic curve to obtain the target performance information of the target compressor under the target operating conditions. Specifically, the performance analysis based on the target operating parameters and the normalized characteristic curve to obtain the target performance information of the target compressor under the target operating conditions includes: performing performance analysis based on the target operating parameters and the normalized characteristic curve; when the analysis determines that the target compressor is in the congested flow operating region, using the congested flow coefficient as a fixed input, determining the currently measured evaporator saturation temperature according to the target operating parameters, and backward calculating the corresponding refrigerant mass flow rate; and calculating the predicted cooling capacity based on the currently measured inlet and outlet enthalpy difference, thereby evaluating the target performance information of the refrigeration unit under the congested flow operating conditions.

5. An electronic device, characterized in that, The electronic device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the compressor performance prediction method according to any one of claims 1 to 3.

6. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the compressor performance prediction method according to any one of claims 1 to 3.

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