Method and device for determining initial opening degree of electronic expansion valve, refrigerating system and storage medium

Abstract

The invention discloses a method and device for determining the initial opening degree of an electronic expansion valve, a refrigerating system and a storage medium. After the refrigerating system is started, the initial opening degree of the electronic expansion valve needs to be determined based on the compressor outlet refrigerant density, the compressor displacement, the electronic expansion valve inlet refrigerant density, the electronic expansion valve inlet and outlet pressure difference, the refrigerant flow coefficient and the proportionality coefficient; and determining the initial opening degree of the electronic expansion valve. Through the mode of determining the initial opening degree of the electronic expansion valve based on the multiple parameters, the initial opening degree of the electronic expansion valve can be rapidly responded and accurately determined, the pressure and flow in the refrigerating system are stabilized, the system fluctuation and fault risk is reduced, the service life is prolonged, and the cost is reduced. The technical problem that the initial opening degree of the electronic expansion valve cannot be accurately determined in the prior art is solved.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of refrigeration systems, and in particular, to a method and device for determining the initial opening degree of an electronic expansion valve, a refrigeration system, and a storage medium. Background Art

[0002] A refrigeration system is a device that uses external energy to transfer heat from a low-temperature substance (or environment) to a high-temperature substance (or environment). Its core function is to achieve temperature control through the circulation of a refrigerant. The refrigeration system mainly consists of a compressor, a condenser, an electronic expansion valve, and an evaporator. In a refrigeration system, the opening degree of the electronic expansion valve is a key parameter affecting the system performance. Accurately determining the optimal initial opening degree of the electronic expansion valve is crucial for improving the energy efficiency, stability, and refrigeration effect of the refrigeration system.

[0003] However, there are generally two ways to determine the initial opening degree of the electronic expansion valve at present. One is to manually determine it, but the manual determination method is inefficient, and due to human subjective factors, it is difficult to ensure the adjustment accuracy. The other way is to automatically determine it by the refrigeration system, but the current method of automatically determining the initial opening degree by the refrigeration system cannot match the actual needs of the refrigeration system under different working conditions, seriously restricting the performance of the refrigeration system. Summary of the Invention

[0004] The present application provides a method and device for determining the initial opening degree of an electronic expansion valve, a refrigeration system, and a storage medium, which solve the technical problem in the prior art that the initial opening degree of the electronic expansion valve cannot be accurately determined.

[0005] In a first aspect, the present application provides a method for determining the initial opening degree of an electronic expansion valve. The method is applicable to a refrigeration system and includes:

[0006] In response to a system startup instruction, determine the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference across the electronic expansion valve, the refrigerant flow coefficient, and a proportionality coefficient under the current working condition. The proportionality coefficient is the ratio of the flow area of the electronic expansion valve to the opening degree.

[0007] Based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference across the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient, determine the initial opening degree of the electronic expansion valve.

[0008] Wherein, the determining the initial opening degree of the electronic expansion valve based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference across the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient includes:

[0009] Input the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the inlet of the electronic expansion valve, the pressure difference across the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient into a preset formula to determine the initial opening degree of the electronic expansion valve. The preset formula is as follows:

[0010]

[0011] where Y is the initial opening degree of the electronic expansion valve, C D is the refrigerant flow coefficient, k is the proportionality coefficient, ρ valve is the refrigerant liquid density at the inlet of the electronic expansion valve, Δp is the pressure difference across the electronic expansion valve, ρ comp is the refrigerant density at the compressor outlet, and Q is the compressor displacement.

[0012] Among them, after determining the initial opening degree of the electronic expansion valve, it further includes:

[0013] Determine the current ambient temperature, compressor discharge pressure, evaporator pressure, and compressor discharge temperature in real time;

[0014] Based on the ambient temperature, the compressor discharge pressure, the evaporator pressure, the compressor discharge temperature, and a preset opening range, correct the initial opening degree.

[0015] Among them, the correcting the initial opening degree based on the ambient temperature, the compressor discharge pressure, the evaporator pressure, the compressor discharge temperature, and a preset opening range includes:

[0016] Correct the initial opening degree according to the ambient temperature to obtain a first initial opening degree;

[0017] When the compressor discharge pressure exceeds a preset discharge pressure threshold, reduce the first initial opening degree;

[0018] When the compressor discharge temperature exceeds a preset temperature threshold, increase the first initial opening degree;

[0019] Among them, the first initial opening degree is always limited within the preset opening range, and when the evaporator pressure is less than a preset pressure threshold, update the minimum value of the preset opening range.

[0020] Among them, the correcting the initial opening degree according to the ambient temperature to obtain a first initial opening degree includes:

[0021] Determine a temperature correction coefficient according to the temperature range where the ambient temperature is located;

[0022] Based on the temperature correction coefficient, correct the initial opening degree to obtain the first initial opening degree.

[0023] Wherein, after determining the initial opening degree of the electronic expansion valve, it further includes:

[0024] Adjust the opening degree of the electronic expansion valve to the initial opening degree;

[0025] During operation, determine the system operation parameters in real time, and dynamically adjust the opening degree of the electronic expansion valve according to the system operation parameters.

[0026] Wherein, the real-time determination of the system operation parameters and the dynamic adjustment of the opening degree of the electronic expansion valve according to the system operation parameters include:

[0027] Determine the superheat degree, the compressor suction pressure, and the compressor displacement in real time;

[0028] Dynamically adjust the opening degree of the electronic expansion valve according to the superheat degree, the compressor suction pressure, and the compressor displacement.

[0029] In a second aspect, the present application provides an electronic expansion valve initial opening degree determination device, which is applicable to a refrigeration system, and the device includes:

[0030] A data acquisition module, configured to determine the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient under the current working condition in response to a system startup instruction, where the proportionality coefficient is the ratio of the flow area of the electronic expansion valve to the opening degree;

[0031] An initial opening degree determination module, configured to determine the initial opening degree of the electronic expansion valve based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient.

[0032] In a third aspect, the present application provides a refrigeration system, which includes a processor and a memory;

[0033] The memory is used to store a computer program and transmit the computer program to the processor;

[0034] The processor is configured to execute the electronic expansion valve initial opening degree determination method as described in the first aspect according to the instructions in the computer program.

[0035] Fourthly, the present application provides a storage medium storing computer-executable instructions, and the computer-executable instructions are used to execute the method for determining the initial opening degree of the electronic expansion valve as described in the first aspect when executed by a computer processor.

[0036] As described above, the present application discloses a method, a device, a refrigeration system and a storage medium for determining the initial opening degree of an electronic expansion valve. After the refrigeration system in the present application is started, it is necessary to determine the initial opening degree of the electronic expansion valve based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient and the proportional coefficient. By determining the initial opening degree of the electronic expansion valve based on multiple parameters, the present application can quickly respond and accurately determine the initial opening degree of the electronic expansion valve, stabilize the pressure and flow rate in the refrigeration system, reduce the system fluctuation and failure risk, extend the service life, and solve the technical problem that the initial opening degree of the electronic expansion valve cannot be accurately determined in the prior art. Description of the Drawings

[0037] Figure 1 It is a schematic flowchart of a method for determining the initial opening degree of an electronic expansion valve provided by an embodiment of the present invention.

[0038] Figure 2 It is a schematic flowchart of a refrigeration system for adjusting the initial opening degree of an electronic expansion valve provided by an embodiment of the present invention.

[0039] Figure 3 It is a schematic structural diagram of a device for determining the initial opening degree of an electronic expansion valve provided by an embodiment of the present invention.

[0040] Figure 4 It is a schematic structural diagram of a refrigeration system provided by an embodiment of the present invention. Detailed Embodiments

[0041] The following description and the accompanying drawings fully disclose specific embodiments of the present application, enabling those skilled in the art to practice them. The embodiments merely represent possible variations. Unless explicitly required, individual components and functions are optional, and the order of operations can vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of the present application includes the entire scope of the claims and all available equivalents of the claims. In this document, the embodiments may be individually or collectively referred to by the term "invention" for convenience only, and if more than one invention is actually disclosed, it is not intended to automatically limit the scope of the application to any single invention or inventive concept. In this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method or device comprising a series of elements includes not only those elements but also other elements not expressly listed. The various embodiments in this document are described in a progressive manner, with each embodiment highlighting the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the structures, products, etc. disclosed in the embodiments, since they correspond to the parts disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0042] A refrigeration system is a device that uses external energy to transfer heat from a low-temperature substance (or environment) to a high-temperature substance (or environment). Its core function is to achieve temperature control through the circulation of a refrigerant. For example, the refrigeration system can be an air conditioner or a refrigerator. The refrigeration system mainly consists of a compressor, a condenser, an electronic expansion valve, and an evaporator. Specifically, the compressor compresses the low-temperature and low-pressure gaseous refrigerant into a high-temperature and high-pressure gas. The high-temperature and high-pressure gas releases heat to the environment (air / water) in the condenser and condenses into a high-pressure liquid refrigerant. Then, the high-pressure liquid refrigerant throttles through the electronic expansion valve, reducing the pressure and temperature to a low-temperature and low-pressure refrigerant. The low-temperature and low-pressure refrigerant absorbs heat (from the surrounding air / water) in the evaporator and evaporates into a low-temperature and low-pressure gas. In the refrigeration system, the opening degree of the electronic expansion valve is a key parameter affecting the system performance. The change in the opening degree of the electronic expansion valve directly changes the throttling cross-sectional area and affects the flow rate of the high-pressure liquid refrigerant entering the evaporator. Therefore, accurately determining the optimal initial opening degree of the electronic expansion valve is crucial for improving the energy efficiency, stability, and refrigeration effect of the refrigeration system.

[0043] However, currently there are generally two ways to determine the initial opening degree of the electronic expansion valve. One is to determine it manually, but this method is inefficient, and due to subjective human factors, it is difficult to guarantee the adjustment accuracy. The other way is to determine it automatically by the refrigeration system, but currently the method of automatically determining the initial opening degree by the refrigeration system cannot match the real needs of the refrigeration system under different working conditions, which seriously restricts the performance of the refrigeration system.

[0044] Based on this, in order to solve the technical problem in the prior art that the initial opening degree of the electronic expansion valve cannot be accurately determined, the embodiment of the present invention provides a method for determining the initial opening degree of the electronic expansion valve, as Figure 1 shown Figure 1 is a schematic flow chart of a method for determining the initial opening degree of the electronic expansion valve provided by the embodiment of the present invention. The method for determining the initial opening degree of the electronic expansion valve provided by the embodiment of the present invention is applicable to the refrigeration system. The method for determining the initial opening degree of the electronic expansion valve includes:

[0045] Step 101, in response to the system start instruction, determine the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient under the current working condition. The proportionality coefficient is the ratio of the flow area of the electronic expansion valve to the opening degree.

[0046] In this embodiment, when the user needs to start the refrigeration system, the refrigeration system can be started by sending a system start instruction to the refrigeration system. Specifically, a start button is provided on the refrigeration system, and the user sends a system start instruction to the refrigeration system by pressing the start button. After receiving the system start instruction, the refrigeration system starts and initializes, and operates in a low-load state. During the operation in the low-load state, the refrigeration system needs to determine the current refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient. The proportionality coefficient is the ratio of the flow area of the electronic expansion valve to the opening degree.

[0047] Among them, the refrigerant density at the compressor outlet can be obtained by setting a pressure sensor and a temperature sensor in the compressor to detect the discharge pressure and discharge temperature respectively. After the refrigeration system reads the discharge pressure collected by the pressure sensor and the discharge temperature collected by the temperature sensor, the discharge pressure and discharge temperature are substituted into the physical property formula for calculation. The refrigerant density at the inlet of the electronic expansion valve can be directly measured by installing a densitometer at the inlet of the electronic expansion valve. The pressure difference between the inlet and outlet of the electronic expansion valve can be obtained by setting pressure sensors at the inlet (high-pressure side) and outlet (low-pressure side) of the electronic expansion valve respectively, and the refrigeration system calculates the pressure difference between the two pressure sensors. The refrigerant flow coefficient can be determined by querying the relationship curve between the flow coefficient and the opening degree provided by the electronic expansion valve manufacturer. The proportionality coefficient can be determined by querying the product manual of the electronic expansion valve, or by measuring the refrigerant flow at different opening degrees under stable operating conditions, combining the pressure difference and density to calculate the actual flow area, and fitting the proportionality coefficient curve. The compressor displacement can be determined by reading the status parameters of the compressor. It can be understood that the specific acquisition methods of the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the inlet of the electronic expansion valve, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient can be set according to actual needs, and are not specifically limited in this embodiment.

[0048] Step 102: Determine the initial opening degree of the electronic expansion valve based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the inlet of the electronic expansion valve, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient.

[0049] After collecting the refrigerant density at the compressor outlet, compressor displacement, refrigerant density at the inlet of the electronic expansion valve, pressure difference across the electronic expansion valve, refrigerant flow coefficient, and proportionality coefficient under a low-load state, the refrigeration system can determine the initial opening degree of the electronic expansion valve based on the refrigerant density at the compressor outlet, compressor displacement, refrigerant density at the inlet of the electronic expansion valve, pressure difference across the electronic expansion valve, refrigerant flow coefficient, and proportionality coefficient. In one embodiment, the refrigeration system can input the refrigerant density at the compressor outlet, compressor displacement, refrigerant density at the inlet of the electronic expansion valve, pressure difference across the electronic expansion valve, refrigerant flow coefficient, and proportionality coefficient into a formula preset by the user to directly calculate the initial opening degree of the electronic expansion valve through the formula. Alternatively, the refrigeration system can input the refrigerant density at the compressor outlet, compressor displacement, refrigerant density at the inlet of the electronic expansion valve, pressure difference across the electronic expansion valve, refrigerant flow coefficient, and proportionality coefficient into a pre-trained initial opening degree prediction model to output the initial opening degree of the electronic expansion valve through the initial opening degree prediction model, where the initial opening degree prediction model can be obtained by training a fully connected neural network (DNN) or a long short-term memory network (LSTM). Exemplarily, when training the initial opening degree prediction model, historical operating condition data such as the refrigerant density at the compressor outlet, compressor displacement, refrigerant density at the inlet of the electronic expansion valve, pressure difference across the inlet and outlet, flow coefficient, and proportionality coefficient of the refrigeration system in history can be collected, and at the same time, the optimal initial opening degree of the electronic expansion valve corresponding to the historical operating condition data is recorded (the optimal initial opening degree can be obtained through PID control or experimental calibration) to obtain a data set. Then, the data set is divided, with 70% of the data in the data set as the training set and 15% of the data as the validation set. The training set is input into a neural network (fully connected neural network or long short-term memory network) for training. During the training process, the mean square error (MSE) is used to measure the deviation between the initial opening degree predicted by the neural network and the optimal initial opening degree, and the learning rate of the neural network is dynamically adjusted through the Adam optimizer. Cross-validation is combined to prevent overfitting, and the initial opening degree prediction error of the test set needs to be controlled within ±5%. Otherwise, the number of network layers or the activation function needs to be adjusted. After the neural network training is completed, the initial opening degree prediction model can be obtained. At this time, the performance of the initial opening degree prediction model is verified using the validation set to determine the performance of the initial opening degree prediction model.

[0050] Based on the refrigerant density at the compressor outlet, compressor displacement, refrigerant density at the inlet of the electronic expansion valve, pressure difference across the electronic expansion valve, refrigerant flow coefficient, and proportionality coefficient in the above embodiment, determining the initial opening degree of the electronic expansion valve in step 102 includes:

[0051] Input the refrigerant density at the compressor outlet, compressor displacement, refrigerant density at the inlet of the electronic expansion valve, pressure difference across the electronic expansion valve, refrigerant flow coefficient, and proportionality coefficient into a preset formula to determine the initial opening degree of the electronic expansion valve. The preset formula is shown in formula (1):

[0052]

[0053] Among them, Y is the initial opening degree of the electronic expansion valve, C D is the refrigerant flow coefficient, k is the proportionality coefficient, ρ valve (kg / m 3 ) is the density of the refrigerant liquid at the inlet of the electronic expansion valve, Δp (Pa) is the pressure difference between the inlet and outlet of the electronic expansion valve, ρ comp (kg / m 3 ) is the density of the refrigerant at the outlet of the compressor, Q (m 3 / s) is the displacement of the compressor.

[0054] Specifically, the derivation process of the preset formula is as follows:

[0055] The flow relationship of the fluid passing through the electronic expansion valve is shown in Formula 2:

[0056]

[0057] Among them: Q flo w (kg / S) is the flow rate of the refrigerant; A (m 2 ) is the flow area of the electronic expansion valve.

[0058] The opening degree Y of the electronic expansion valve is usually expressed as a percentage (e.g., 0% ≤ Y ≤ 100%), and its flow area A has a linear relationship with the opening degree Y, as shown in Formula (3):

[0059] A = k·Y (3)

[0060] There is a balance relationship between the refrigerant mass flow rate at the outlet of the compressor and the refrigerant mass flow rate of the electronic expansion valve as shown in Formula (4):

[0061] ρ comp ·Q = ρ valve .Q flow (4)

[0062] When the refrigeration system is stable, the flow rate of the electronic expansion valve matches the mass flow rate of the compressor, and there is a relationship as shown in Formula (5):

[0063]

[0064] By combining Formulas (2), (3), and (5), the relationship between the opening degree of the electronic expansion valve and the displacement of the compressor can be deduced, that is, Formula (1) is obtained.

[0065] Exemplarily, assume that after the refrigeration system is started and enters the refrigeration working condition, the following working condition parameters collected by the refrigeration system are as follows:

[0066] Refrigerant density at the compressor outlet: ρ comp = 450 kg / m 3 ;

[0067] Compressor displacement: Q = 0.018 m 3 / s

[0068] Refrigerant flow coefficient: C D = 0.7

[0069] Proportionality coefficient: k = 0.0009 m 2

[0070] Refrigerant liquid density at the inlet of the electronic expansion valve: ρ valve = 1100 kg / m 3

[0071] Pressure difference across the electronic expansion valve: Δp = 1.2×10 5 Pa

[0072] Substitute into formula (1):

[0073]

[0074] In another embodiment, it is assumed that after the refrigeration system starts up and enters the heating mode, the operating condition parameters collected by the refrigeration system are as follows:

[0075] Refrigerant density at the compressor outlet: ρ comp = 400 kg / m 3 ;

[0076] Compressor displacement: Q = 0.015 m 3 / s

[0077] Refrigerant flow coefficient: C D = 0.68

[0078] Proportionality coefficient: k = 0.0008 m 2

[0079] Refrigerant liquid density at the inlet of the electronic expansion valve: ρ valve = 1000 kg / m 3

[0080] Pressure difference across the electronic expansion valve: Δp = 1.0×10 5 Pa

[0081] Substitute into formula (1):

[0082]

[0083] In another embodiment, when ρ comp 、C D, k, ρ valve When Δp is fixed, the larger Q is, the larger the initial opening Y is. That is, the refrigeration system needs to increase the opening of the electronic expansion valve to match the higher refrigerant flow demand and ensure the refrigerant supply for the refrigeration / heating cycle. Since the ambient temperature is positively correlated with the evaporation temperature, the higher the ambient temperature, the higher the evaporation temperature, and the higher the evaporation temperature, the larger the refrigerant flow and the larger Q is.

[0084] Suppose the initial frequency of the compressor is 50 Hz and the ambient temperature is 35 °C. The refrigerant flow is shown in Table 1:

[0085] Table 1

[0086]

[0087] The corresponding initial openings under different compressor displacements are shown in Table 2:

[0088] Table 2

[0089] <![CDATA[Compressor displacement Q (m 3 / s)]]> Initial opening Y (%) 0.001 5.0％ 0.003 13.19％ 0.005 22.0％ 0.008 35.17％ 0.012 52.7％ 0.016 69.9％ 0.020 87.0％ 0.021 95.0％

[0090] The above is the process of determining the initial opening of the electronic expansion valve. In addition, the embodiments of the present invention can dynamically adjust the coefficient related to the compressor displacement, so that the method for determining the initial opening can adapt to compressors with different displacements and has stronger versatility and flexibility.

[0091] On the basis of the above embodiments, after determining the initial opening of the electronic expansion valve, it further includes:

[0092] Step 103: Real-time determine the current ambient temperature, compressor discharge pressure, evaporator pressure, and compressor discharge temperature.

[0093] Step 104: Correct the initial opening based on the ambient temperature, compressor discharge pressure, evaporator pressure, compressor discharge temperature, and a preset opening range.

[0094] In one embodiment, after determining the initial opening degree of the electronic expansion valve, the refrigeration system further needs to correct the initial opening degree. Specifically, after determining the initial opening degree, the refrigeration system needs to further determine the current ambient temperature, compressor discharge pressure, evaporator pressure, and compressor discharge temperature in real time. Among them, the ambient temperature can be collected by a temperature sensor set in the monitored ambient area; the compressor discharge pressure can be collected by a pressure sensor set in the straight pipe section after the compressor discharge valve; the evaporator pressure can be collected by a pressure sensor set in the pipeline from the evaporator outlet to the compressor suction valve; the compressor discharge temperature can be collected by a temperature sensor set on the outer wall of the compressor discharge pipeline. It can be understood that the collection methods of the ambient temperature, compressor discharge pressure, evaporator pressure, and compressor discharge temperature can be set according to actual needs, and are not specifically limited in this embodiment. In addition, the preset opening range is the opening range preset by the user, and the preset opening range can be input by the user into the refrigeration system, or uploaded by the user to the cloud and then obtained by the refrigeration system from the cloud.

[0095] After the refrigeration system confirms the ambient temperature, compressor discharge pressure, evaporator pressure, compressor discharge temperature, and the preset opening range, it can correct the initial opening degree determined based on formula (1). For example, the change in ambient temperature directly affects the evaporator heat load, and the refrigeration system needs to adjust the initial opening degree according to the evaporator heat load. When the compressor discharge pressure is too high (such as exceeding 3.5 MPa), the initial opening degree needs to be reduced to lower the pressure on the evaporator side. When the evaporation pressure is too low (close to negative pressure), the initial opening degree needs to be reduced to avoid incomplete evaporation and prevent liquid slugging of the compressor. The high exhaust temperature protection will trigger an increase in the initial opening degree to strengthen cooling and protect the compressor.

[0096] Specifically, in step 104, based on the ambient temperature, compressor discharge pressure, evaporator pressure, compressor discharge temperature, and the preset opening range, correcting the initial opening degree includes:

[0097] Step 1041: Correct the initial opening degree according to the ambient temperature to obtain the first initial opening degree.

[0098] In this embodiment, the refrigeration system first needs to correct the initial opening degree according to the ambient temperature. Among them, the ambient temperature directly affects the evaporator heat load. When the ambient temperature rises, the opening degree of the electronic expansion valve needs to be increased to match the increased refrigeration demand. Conversely, the opening degree of the electronic expansion valve needs to be reduced to avoid over-expansion. In one embodiment, the refrigeration system can determine the temperature correction coefficient according to the temperature range where the ambient temperature is located; correct the initial opening degree based on the temperature correction coefficient to obtain the first initial opening degree. The temperature correction coefficients corresponding to different temperature ranges need to be preset by the user. Exemplarily, the temperature correction coefficients corresponding to different temperature ranges are shown in Table 3:

[0099] Table 3

[0100] Temperature range (°C) Temperature correction factor -20～0 0.9～0.95 0～25 1 25～45 1.15～1.20

[0101] After determining the temperature correction coefficient corresponding to the temperature range, the initial opening can be corrected according to the ambient temperature. Multiply the temperature correction coefficient by the initial opening to obtain the first initial opening. It can be understood that when the temperature range is 0 - 25°C, there is no need to correct the initial opening, but the initial opening still needs to be recorded as the first initial opening.

[0102] Step 1042: When the compressor discharge pressure exceeds the preset discharge pressure threshold, reduce the first initial opening.

[0103] After correcting the initial opening according to the ambient temperature, if the refrigeration system determines that the current compressor discharge pressure exceeds the preset discharge pressure threshold, it is necessary to reduce the first initial opening to reduce the refrigerant flow rate into the evaporator, thereby reducing the pressure on the evaporator side, reducing the compression ratio of the compressor (discharge pressure / suction pressure), and avoiding a sharp rise in the compressor discharge temperature due to too high a compression ratio, thereby protecting the compressor motor and lubricating oil from high-temperature damage. In addition, the preset discharge pressure threshold can be set in advance according to actual needs.

[0104] Step 1043: When the compressor discharge temperature exceeds the preset temperature threshold, increase the first initial opening.

[0105] In addition, if the refrigeration system detects that the current compressor discharge temperature exceeds the preset temperature threshold, it is necessary to increase the first initial opening to increase the liquid supply amount to the evaporator, reduce the superheat degree of the refrigerant in the evaporator, thereby reducing the suction gas temperature, and alleviating the situation of the compressor discharge temperature rising due to too high a suction gas temperature. In addition, the preset temperature threshold can be set in advance according to actual needs, for example, it can be set to 105°C. It should be noted that for the refrigeration system, it is usually not the case that both the compressor discharge pressure exceeds the preset discharge pressure threshold and the compressor discharge temperature exceeds the preset temperature threshold, that is, it is difficult for the refrigeration system to require reducing the first initial opening and increasing the first initial opening at the same time. If both of the above situations occur simultaneously, it indicates that the refrigeration system has a complex serious fault and needs to be shut down for maintenance immediately, that is, there is no need to correct the first initial opening at this time.

[0106] Among them, the first initial opening is always limited within the preset opening range, and when the evaporator pressure is less than the preset pressure threshold, update the minimum value of the preset opening range.

[0107] It should be noted that in this embodiment, the first initial opening degree always needs to be restricted within a preset opening range. For example, the opening range can be set to 5% - 95% to avoid liquid slugging of the compressor caused by the full opening of the electronic expansion valve or refrigerant cutoff caused by the full closing under extreme working conditions. When the first initial opening degree exceeds the preset opening range, the first initial opening degree needs to be updated to the boundary value of the closest opening range. For example, when the first initial opening degree is 97%, the first initial opening degree needs to be updated to 95%; when the first initial opening degree is 3%, the first initial opening degree needs to be updated to 5%. Additionally, when the refrigeration system determines that the evaporator pressure is less than the preset pressure threshold, it is necessary to update the minimum value of the preset opening range, and the updated minimum value needs to be greater than the original preset minimum value of the opening range. For example, if the original preset minimum value of the opening range is 5%, the updated minimum value needs to be greater than 5%. The reason is that excessively closing the electronic expansion valve will significantly reduce the refrigerant flow rate into the evaporator, exacerbate the evaporation pressure drop, and may trigger an alarm for too low suction pressure of the compressor or even shutdown due to low-pressure protection. By increasing the minimum opening degree, the basic flow rate can be maintained, preventing the evaporator from losing its heat exchange capacity due to complete cutoff of the refrigerant flow, and at the same time ensuring the cooling and lubrication requirements of the compressor. It can be understood that if, after the refrigeration system updates the minimum value of the preset opening range, it detects that the evaporator pressure is greater than or equal to the preset pressure threshold, the minimum value of the opening range needs to be restored to the original preset minimum value, for example, restored to 5%.

[0108] In one embodiment, as Figure 2 shown, Figure 2 is a schematic flow chart of a refrigeration system provided by an embodiment of the present invention for adjusting the initial opening degree of an electronic expansion valve. Figure 2 In, after the refrigeration system initializes in response to a system startup command, it collects operating parameters (including the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the inlet of the electronic expansion valve, the pressure difference across the electronic expansion valve, the refrigerant flow coefficient, and the proportional coefficient), and then inputs the operating parameters into formula (1) for calculation to determine the initial opening degree of the electronic expansion valve, and further corrects the initial opening degree based on factors such as the preset opening range to obtain the first initial opening degree. Finally, the refrigeration system generates an initial opening degree control signal according to the first initial opening degree and sends the initial opening degree control signal to the electronic expansion valve so that the electronic expansion valve adjusts its opening degree to the first initial opening degree.

[0109] Based on the above embodiment, after determining the initial opening degree of the electronic expansion valve, it further includes:

[0110] Step 105: Adjust the opening degree of the electronic expansion valve to the initial opening degree.

[0111] Step 106: During operation, continuously determine the system operating parameters and dynamically adjust the opening degree of the electronic expansion valve according to the system operating parameters.

[0112] In this embodiment, after the refrigeration system determines the initial opening degree (if corrected, the initial opening degree here is the first initial opening degree), it adjusts the opening degree of the electronic expansion valve to the initial opening degree and continues to operate. After operating for a period of time (such as 2 minutes), the refrigeration system needs to determine the system operating parameters in real time and dynamically adjust the opening degree of the electronic expansion valve according to the system operating parameters to ensure the stable operation of the system. In one embodiment, the system operating parameters include superheat degree, compressor suction pressure, and compressor displacement. The refrigeration system needs to determine the superheat degree, compressor suction pressure, and compressor displacement in real time, and dynamically adjust the opening degree of the electronic expansion valve according to the superheat degree, compressor suction pressure, and compressor displacement. Specifically, the refrigeration system can control the opening degree of the electronic expansion valve in coordination with the superheat degree and compressor suction pressure. Among them, superheat degree = refrigerant temperature at the outlet of the evaporator - saturation temperature corresponding to the suction pressure. When the superheat degree is too large, the refrigerant is insufficient. Therefore, it is necessary to increase the opening degree of the electronic expansion valve to increase the refrigerant flow rate, so that more refrigerant enters the evaporator for vaporization and reduces the superheat degree. When the superheat degree is too small, it is necessary to reduce the opening degree of the electronic expansion valve to reduce the refrigerant flow rate and avoid liquid refrigerant being sucked into the compressor without being completely vaporized. The compressor suction pressure directly reflects the pressure in the evaporator and corresponds one-to-one with the evaporation temperature. The compressor suction pressure is affected by two factors: refrigerant flow rate and heat load. When the refrigerant flow rate is insufficient, the compressor suction pressure decreases. When the refrigerant flow rate is too large, the compressor suction pressure increases. When the heat load of the evaporator increases (such as the room temperature rises), the compressor suction pressure may rise in the short term. In summary, when the compressor suction pressure is low and the superheat degree is high, the refrigerant is insufficient. At this time, the refrigeration system should greatly increase the opening degree of the electronic expansion valve. When the compressor suction pressure is high and the superheat degree is low, the refrigerant is excessive. At this time, the refrigeration system should quickly reduce the opening degree of the electronic expansion valve.

[0113] When the refrigeration system detects a change in the compressor displacement, it can directly input the changed compressor displacement into the above formula (1) for calculation to recalculate the opening degree of the electronic expansion valve and adjust the opening degree of the electronic expansion valve according to the recalculated opening degree. Additionally, it can be understood that during the process of the refrigeration system dynamically adjusting the opening degree of the electronic expansion valve, the opening degree of the electronic expansion valve also needs to be limited within a preset opening degree range.

[0114] As described above, the embodiment of the present invention provides a method for determining the initial opening degree of an electronic expansion valve. After the refrigeration system is started, it is necessary to determine the initial opening degree of the electronic expansion valve based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient. By determining the initial opening degree of the electronic expansion valve based on multiple parameters, the embodiment of the present invention can quickly respond and accurately determine the initial opening degree of the electronic expansion valve, stabilize the pressure and flow rate in the refrigeration system, reduce the system fluctuation and failure risk, and extend the service life. In addition, by accurately determining the initial opening degree of the electronic expansion valve, the embodiment of the present invention can make the refrigerant flow rate match the actual demand of the refrigeration system, give full play to the heat exchange capacity of the evaporator, reduce the unnecessary energy consumption of the compressor, improve the energy-saving effect, and the energy-saving benefit is more significant for the scenario of large-scale use of the refrigeration system.

[0115] The embodiment of the present invention also provides an apparatus for determining the initial opening degree of an electronic expansion valve, as Figure 3 shown Figure 3 is a schematic structural diagram of an apparatus for determining the initial opening degree of an electronic expansion valve provided by the embodiment of the present invention. The apparatus for determining the initial opening degree of an electronic expansion valve includes:

[0116] A data acquisition module 201, configured to determine the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient under the current working condition in response to a system start instruction, where the proportionality coefficient is the ratio of the flow area of the electronic expansion valve to the opening degree;

[0117] An initial opening degree determination module 202, configured to determine the initial opening degree of the electronic expansion valve based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient.

[0118] Among them, the initial opening degree determination module 202 is specifically configured to input the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference between the inlet and outlet of the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient into a preset formula to determine the initial opening degree of the electronic expansion valve. The preset formula is:

[0119]

[0120] Among them, Y is the initial opening degree of the electronic expansion valve, C D is the refrigerant flow coefficient, k is the proportionality coefficient, ρ valve is the refrigerant liquid density at the electronic expansion valve inlet, Δp is the pressure difference between the inlet and outlet of the electronic expansion valve, ρ comp is the refrigerant density at the compressor outlet, and Q is the compressor displacement.

[0121] Among them, it further includes:

[0122] A real-time parameter determination module, configured to determine the current ambient temperature, compressor discharge pressure, evaporator pressure, and compressor discharge temperature in real time after determining the initial opening degree of the electronic expansion valve;

[0123] An initial opening degree correction module, configured to correct the initial opening degree based on the ambient temperature, compressor discharge pressure, evaporator pressure, compressor discharge temperature, and a preset opening degree range.

[0124] Among them, the initial opening degree correction module includes:

[0125] A first correction sub-module, configured to correct the initial opening degree according to the ambient temperature to obtain a first initial opening degree;

[0126] A second correction sub-module, configured to reduce the first initial opening degree when the compressor discharge pressure exceeds a preset discharge pressure threshold;

[0127] A third correction sub-module, configured to increase the first initial opening degree when the compressor discharge temperature exceeds a preset temperature threshold;

[0128] Among them, the first initial opening degree is always limited within the preset opening degree range, and when the evaporator pressure is less than the preset pressure threshold, the minimum value of the preset opening degree range is updated.

[0129] Among them, the first correction sub-module includes:

[0130] A correction coefficient determination unit, configured to determine a temperature correction coefficient according to the temperature range where the ambient temperature is located;

[0131] An initial opening degree correction unit, configured to correct the initial opening degree based on the temperature correction coefficient to obtain a first initial opening degree.

[0132] Among them, it further includes:

[0133] An opening degree adjustment module, configured to adjust the opening degree of the electronic expansion valve to the initial opening degree after determining the initial opening degree of the electronic expansion valve;

[0134] An opening degree dynamic adjustment module, configured to determine the system operation parameters in real time during operation, and dynamically adjust the opening degree of the electronic expansion valve according to the system operation parameters.

[0135] Among them, the opening degree dynamic adjustment module is specifically configured to determine the superheat degree, compressor suction pressure, and compressor displacement in real time; and dynamically adjust the opening degree of the electronic expansion valve according to the superheat degree, compressor suction pressure, and compressor displacement.

[0136] The electronic expansion valve initial opening degree determination device provided by the embodiment of the present invention is included in the refrigeration system and can be used to execute the electronic expansion valve initial opening degree determination method provided in the above embodiment, and has corresponding functions and beneficial effects.

[0137] It should be noted that in the embodiments of the above electronic expansion valve initial opening degree determination device, the various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be realized; in addition, the specific names of the functional units are only for the convenience of mutual distinction and do not limit the protection scope of the present invention.

[0138] This embodiment also provides a refrigeration system, as Figure 4 shown Figure 4 is a schematic structural diagram of a refrigeration system provided by an embodiment of the present invention. The refrigeration system 30 includes a processor 300 and a memory 301;

[0139] The memory 301 is used to store the computer program 302 and transmit the computer program 302 to the processor 300;

[0140] The processor 300 is used to execute the steps in the above embodiment of the electronic expansion valve initial opening degree determination method according to the instructions in the computer program 302.

[0141] Exemplarily, the computer program 302 can be divided into one or more modules / units. One or more modules / units are stored in the memory 301 and executed by the processor 300 to complete the present application. One or more modules / units can be a series of computer program instruction segments capable of completing specific functions, and these instruction segments are used to describe the execution process of the computer program 302 in the refrigeration system 30.

[0142] The refrigeration system 30 may include, but is not limited to, the processor 300 and the memory 301. Those skilled in the art can understand that Figure 4 this is only an example of the refrigeration system 30 and does not constitute a limitation on the refrigeration system 30. It may include more or fewer components than shown in the figure, or combine certain components, or different components. For example, the refrigeration system 30 may also include input / output devices, network access devices, buses, etc.

[0143] The so-called processor 300 may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0144] The memory 301 may be an internal storage unit of the refrigeration system 30, such as the hard disk or memory of the refrigeration system 30. The memory 301 may also be an external storage device of the refrigeration system 30, such as a plug-in hard disk equipped on the refrigeration system 30, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. Further, the memory 301 may also include both the internal storage unit of the refrigeration system 30 and the external storage device. The memory 301 is used to store computer programs and other programs and data required by the refrigeration system 30. The memory 301 may also be used to temporarily store data that has been output or is to be output.

[0145] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0146] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other may be through some interfaces, indirect couplings or communication connections of devices or units, and may be in electrical, mechanical, or other forms.

[0147] The unit described as a separation component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or distributed across multiple network units. Some or all of these units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0148] In addition, each functional unit in various embodiments of the present invention can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0149] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store computer programs such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0150] The embodiment of the present invention also provides a storage medium containing computer-executable instructions. When the computer-executable instructions are executed by a computer processor, they are used to execute a method for determining the initial opening degree of an electronic expansion valve. This is applicable to a refrigeration system, and the method includes the following steps:

[0151] In response to a system startup instruction, determine the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference across the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient under the current operating conditions. The proportionality coefficient is the ratio of the flow area of the electronic expansion valve to the opening degree.

[0152] Based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the pressure difference across the electronic expansion valve, the refrigerant flow coefficient, and the proportionality coefficient, determine the initial opening degree of the electronic expansion valve.

[0153] Note that the above is only the preferred embodiment of the embodiments of the present invention and the technical principles applied. Those skilled in the art will understand that the embodiments of the present invention are not limited to the specific embodiments here, and various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the embodiments of the present invention. Therefore, although the embodiments of the present invention have been described in more detail through the above embodiments, the embodiments of the present invention are not limited to the above embodiments only. Without departing from the concept of the embodiments of the present invention, more other equivalent embodiments can be included, and the scope of the embodiments of the present invention is determined by the scope of the appended claims.

Claims

1. A method for determining the initial opening of an electronic expansion valve, characterized in that: The method is applicable to a refrigeration system, and the method comprises: In response to a system startup instruction, determine the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the electronic expansion valve inlet and outlet pressure difference, the refrigerant flow coefficient and the proportionality coefficient under the current working condition, wherein the proportionality coefficient is the ratio of the flow area to the opening of the electronic expansion valve; The initial opening degree of the electronic expansion valve is determined based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the inlet and outlet pressure difference of the electronic expansion valve, the refrigerant flow coefficient and the proportionality coefficient.

2. The method for determining the initial opening degree of an electronic expansion valve according to claim 1, characterized in that: The determining of the initial opening of the electronic expansion valve based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the inlet and outlet pressure difference of the electronic expansion valve, the refrigerant flow coefficient and the proportional coefficient comprises: The refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the inlet and outlet pressure difference of the electronic expansion valve, the refrigerant flow coefficient and the proportional coefficient are input into a preset formula to determine the initial opening of the electronic expansion valve. The preset formula is: Wherein, Y is the initial opening degree of the electronic expansion valve, C D is the refrigerant flow coefficient, k is the proportional coefficient, ρ valve is the refrigerant liquid density at the inlet of the electronic expansion valve, Δp is the inlet and outlet pressure difference of the electronic expansion valve, ρ comp is the refrigerant density at the compressor outlet, and Q is the compressor displacement.

3. The method for determining the initial opening degree of an electronic expansion valve according to claim 1, characterized in that: After determining the initial opening degree of the electronic expansion valve, the method further includes: Determine the current ambient temperature, compressor discharge pressure, evaporator pressure, and compressor discharge temperature in real time; The initial opening is corrected based on the ambient temperature, the compressor exhaust pressure, the evaporator pressure, the compressor exhaust temperature and a preset opening range.

4. The method for determining the initial opening degree of an electronic expansion valve according to claim 3, characterized in that: The correcting of the initial opening degree based on the ambient temperature, the compressor exhaust pressure, the evaporator pressure, the compressor exhaust temperature and a preset opening range includes: Correcting the initial opening according to the ambient temperature to obtain a first initial opening; When the exhaust pressure of the compressor exceeds a preset exhaust pressure threshold, reducing the first initial opening degree; When the compressor exhaust temperature exceeds a preset temperature threshold, increasing the first initial opening degree; The first initial opening is always limited within the preset opening range, and when the evaporator pressure is less than a preset pressure threshold, the minimum value of the preset opening range is updated.

5. The method for determining the initial opening degree of an electronic expansion valve according to claim 4, characterized in that: The step of correcting the initial opening according to the ambient temperature to obtain a first initial opening includes: Determining a temperature correction coefficient according to the temperature range of the ambient temperature; The initial opening degree is corrected based on the temperature correction coefficient to obtain a first initial opening degree.

6. The method for determining the initial opening degree of an electronic expansion valve according to claim 1, characterized in that: After determining the initial opening degree of the electronic expansion valve, the method further includes: Adjusting the opening of the electronic expansion valve to an initial opening; During operation, system operating parameters are determined in real time, and the opening of the electronic expansion valve is dynamically adjusted according to the system operating parameters.

7. The method for determining the initial opening degree of an electronic expansion valve according to claim 6, characterized in that: The real-time determination of the system operating parameters and the dynamic adjustment of the opening of the electronic expansion valve according to the system operating parameters include: determining superheat, compressor suction pressure, and compressor displacement in real time; The opening degree of the electronic expansion valve is dynamically adjusted according to the superheat, the compressor suction pressure and the compressor displacement.

8. A device for determining the initial opening of an electronic expansion valve, characterized in that: The device is suitable for a refrigeration system, and comprises: A data acquisition module, for responding to a system startup instruction, to determine the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the electronic expansion valve inlet and outlet pressure difference, the refrigerant flow coefficient and the proportionality coefficient under the current working condition, wherein the proportionality coefficient is the ratio of the flow area to the opening of the electronic expansion valve; The initial opening determination module is used to determine the initial opening of the electronic expansion valve based on the refrigerant density at the compressor outlet, the compressor displacement, the refrigerant density at the electronic expansion valve inlet, the inlet and outlet pressure difference of the electronic expansion valve, the refrigerant flow coefficient and the proportional coefficient.

9. A refrigeration system, characterized in that: The refrigeration system includes a processor and a memory; The memory is used to store a computer program and transmit the computer program to the processor; The processor is used to execute the method for determining the initial opening degree of the electronic expansion valve according to any one of claims 1 to 7 according to the instructions in the computer program.

10. A storage medium storing computer executable instructions, characterized in that: The computer executable instructions are used to execute the method for determining the initial opening degree of an electronic expansion valve according to any one of claims 1 to 7 when executed by a computer processor.

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