Refrigerating unit control method, device and equipment and refrigerating system

Abstract

The invention relates to a refrigerating unit control method, device and equipment and a refrigerating system.The refrigerating unit comprises an evaporator, a compressor, a condenser and a flash tank which are sequentially communicated, the flash tank is further communicated with the evaporator and the compressor, and the compressor is of a double-cantilever four-impeller two-stage compression parallel structure; wherein the left guide vane is close to the evaporator, and the right guide vane is close to the condenser. The refrigerating unit control method comprises the steps that the evaporation pressure of an evaporator and the condensation pressure of a condenser are obtained, and first power corresponding to a left side guide vane and second power corresponding to a right side guide vane are determined based on the evaporation pressure and the condensation pressure, and determining a target guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to the minimum sum value of the first power and the second power, and controlling the left guide vane and the right guide vane to work according to the target guide vane opening. And the working performance of the refrigerating unit is improved by calculating the target guide vane adjusting opening degree.

Description

Technical Field

[0001] The present application relates to the field of refrigeration technology, and in particular to a refrigeration unit control method, device, equipment and refrigeration system. Background Art

[0002] The main function of refrigeration units is refrigeration, which can adjust the temperature and has been widely used. The refrigerant currently used in refrigeration units is R134a, but its global warming potential (GWP) is too high. In recent years, various manufacturers have also been looking for alternatives to R134a. R1233zd(E) refrigerant has gradually become a substitute for R134a due to its advantages in ozone depletion potential (ODP) and global warming potential (GWP), as well as high refrigeration efficiency, and has become the future development trend of refrigeration units.

[0003] However, R1233zd(E) has a large specific volume, a large impeller size, and a heavy cantilever. Considering the balance of shaft stress and the coordination of impeller size, the R1233zd(E) compressor with a large cooling capacity is designed as a double-cantilever four-impeller two-stage compression parallel structure, with guide vanes set in front of the impeller inlet on both sides. Under this structure, how to adjust the operating state of the refrigeration unit to enable the refrigeration unit to better perform its working performance has become an urgent problem to be solved. Summary of the invention

[0004] Based on this, it is necessary to provide a refrigeration unit control method, device, equipment and refrigeration system that can improve the working performance of the refrigeration unit in response to the above technical problems.

[0005] In a first aspect, the present application provides a control method for a refrigeration unit, wherein the refrigeration unit comprises an evaporator, a compressor, a condenser and a flasher which are sequentially connected, wherein the flasher is also connected to the evaporator and the compressor, and the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided; the method comprises:

[0006] Obtaining the evaporation pressure of the evaporator and the condensation pressure of the condenser;

[0007] Determining a first power corresponding to the left guide vane and a second power corresponding to the right guide vane based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane;

[0008] determining a target guide vane opening according to an opening of the left guide vane and an opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum;

[0009] The left guide vane and the right guide vane are controlled to operate according to the target guide vane opening.

[0010] In one of the embodiments, determining a first power corresponding to the left guide vane and a second power corresponding to the right guide vane based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane includes:

[0011] determining a pressure ratio percentage based on the evaporation pressure, the condensation pressure, and a rated pressure ratio;

[0012] determining a volumetric flow rate percentage based on the evaporation pressure and the rated specific volume;

[0013] Determining a first power corresponding to the left guide vane according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening of the left guide vane;

[0014] A second power corresponding to the right guide vane is determined according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening degree of the right guide vane.

[0015] In one embodiment, the determining the volume flow percentage based on the evaporation pressure and the rated specific volume comprises:

[0016] determining an actual specific volume based on the vaporization pressure;

[0017] determining a specific volume percentage based on the actual specific volume and the rated specific volume;

[0018] The volume flow percentage is determined according to the specific volume percentage and the opening degree of the left guide vane.

[0019] In one of the embodiments, determining the target guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum includes:

[0020] Determining an optimal guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum;

[0021] determining a minimum guide vane opening based on the evaporation pressure and the condensation pressure;

[0022] A target guide vane opening is determined according to the optimal guide vane opening and the minimum guide vane opening.

[0023] In one of the embodiments, determining the target guide vane opening according to the optimal guide vane opening and the minimum guide vane opening includes:

[0024] In a case where the optimal guide vane opening is greater than the minimum guide vane opening, determining the optimal guide vane opening as a target guide vane opening;

[0025] In a case where the optimal guide vane opening is less than the minimum guide vane opening, the optimal guide vane opening is updated based on the minimum guide vane opening and the specific volume percentage, and the updated optimal guide vane opening is determined as the target guide vane opening; the specific volume percentage is obtained based on the evaporation pressure.

[0026] In one of the embodiments, when the optimal guide vane opening is less than the minimum guide vane opening, after the optimal guide vane opening is updated based on the minimum guide vane opening and the specific volume percentage, and the updated optimal guide vane opening is determined to be the target guide vane opening, and before the left guide vane and the right guide vane are controlled to operate according to the target guide vane opening, the method further includes:

[0027] Control opens the hot gas bypass.

[0028] In one embodiment, the method further comprises:

[0029] The flasher is controlled to supply air to the left guide vane and the right guide vane according to the ratio corresponding to the target guide vane opening.

[0030] In one embodiment, before obtaining the evaporation pressure of the evaporator and the condensation pressure of the condenser, the method further includes:

[0031] When it is determined that capacity adjustment is required, adjusting the operating frequency of the compressor;

[0032] When the capacity requirement is still not met after the operating frequency is adjusted to the minimum value, the step of obtaining the evaporation pressure of the evaporator and the condensation pressure of the condenser is performed.

[0033] In one embodiment, the method further comprises:

[0034] Obtaining the chilled water outlet temperature of the evaporator;

[0035] When the chilled water outlet temperature is greater than a preset temperature threshold, it is determined that capacity adjustment is required.

[0036] In a second aspect, the present application further provides a refrigeration unit control device, the refrigeration unit comprising an evaporator, a compressor, a condenser and a flasher which are sequentially connected, the flasher is also connected to the evaporator and the compressor, the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided; the device comprises:

[0037] A pressure acquisition module, used for acquiring the evaporation pressure of the evaporator and the condensation pressure of the condenser;

[0038] a power determination module, configured to determine a first power corresponding to the left guide vane and a second power corresponding to the right guide vane based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane;

[0039] an opening determination module, configured to determine a target guide vane opening according to an opening of the left guide vane and an opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum;

[0040] The opening adjustment module is used to control the operation of the left guide vane and the right guide vane according to the target guide vane opening.

[0041] In a third aspect, the present application further provides a refrigeration unit control device, the refrigeration unit comprising an evaporator, a compressor, a condenser and a flasher which are sequentially connected, the flasher is also connected to the evaporator and the compressor, the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided;

[0042] The refrigeration unit control device comprises a first pressure sensor, a second pressure sensor and a controller, wherein the first pressure sensor is arranged on the evaporator, the second pressure sensor is arranged on the condenser, and the first pressure sensor and the second pressure sensor are both connected to the controller;

[0043] The first pressure sensor is used to detect the evaporation pressure of the evaporator and send it to the controller; the second pressure sensor is used to detect the condensation pressure of the condenser and send it to the controller; the controller is used to control the refrigeration unit according to the above method.

[0044] In a fourth aspect, the present application also provides a refrigeration system, including a refrigeration unit and a refrigeration unit control device as described above.

[0045] In one embodiment, the refrigeration unit further includes a first electronic expansion valve and a second electronic expansion valve, wherein the first electronic expansion valve is arranged on the channel between the flasher and the evaporator, and the second electronic expansion valve is arranged on the channel between the condenser and the flasher.

[0046] In one embodiment, the refrigeration unit further includes a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve, the first solenoid valve is arranged on the channel between the evaporator and the left guide vane, the second solenoid valve is arranged on the channel between the evaporator and the right guide vane, the third solenoid valve is arranged on the channel between the flasher and the left guide vane, and the fourth solenoid valve is arranged on the channel between the flasher and the right guide vane.

[0047] The above-mentioned refrigeration unit control method, device, equipment and refrigeration system, the refrigeration unit includes an evaporator, a compressor, a condenser and a flasher which are connected in sequence, the flasher is also connected to the evaporator and the compressor, the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided. The refrigeration unit control method includes: obtaining the evaporation pressure of the evaporator and the condensation pressure of the condenser, determining the first power corresponding to the left guide vane and the second power corresponding to the right guide vane based on the evaporation pressure and the condensation pressure, determining the target guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to the minimum sum of the first power and the second power, and controlling the left guide vane and the right guide vane to work according to the target guide vane opening. Combined with the actual operating conditions of the refrigeration unit, by calculating the target guide vane adjustment opening, the energy efficiency after the intervention of the guide vane is improved, so as to improve the reliability of the energy regulation method of the refrigeration unit, thereby improving the working performance of the refrigeration unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0049] FIG1 is a schematic diagram of the structure of a refrigeration unit in one embodiment;

[0050] FIG2 is a schematic flow chart of a refrigeration unit control method in one embodiment;

[0051] 3 is a flow chart of a step of determining a first power corresponding to a left guide vane and a second power corresponding to a right guide vane based on an evaporation pressure, a condensation pressure, an opening of a left guide vane, and an opening of a right guide vane in one embodiment;

[0052] FIG4 is a schematic flow chart of a step of determining a volume flow percentage based on evaporation pressure and rated specific volume in one embodiment;

[0053] 5 is a flow chart of a step of determining a target guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum in one embodiment;

[0054] FIG6 is a schematic flow chart of a step of determining a target guide vane opening according to an optimal guide vane opening and a minimum guide vane opening in one embodiment;

[0055] FIG7 is a schematic flow chart of a refrigeration unit control method in another embodiment;

[0056] FIG8 is a schematic flow chart of a refrigeration unit control method in another embodiment;

[0057] FIG. 9 is a structural block diagram of a refrigeration unit control device in one embodiment. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0059] The refrigeration unit control method provided in the embodiment of the present application is used to control the refrigeration unit. Among them, the refrigeration unit includes but is not limited to a chiller. As shown in Figure 1, the basic structure of the refrigeration unit is: including an evaporator, a compressor, a condenser and a flasher arranged in sequence, the flasher is also connected to the evaporator and the compressor, and the compressor is a double-cantilever four-impeller two-stage compression parallel structure, in which a left guide vane close to the evaporator and a right guide vane close to the condenser are provided. When the refrigeration unit is working, a part of the low-temperature and low-pressure refrigerant gas coming out of the evaporator enters the left side of the compressor according to the current capacity, and enters the inside of the compressor after passing through the left guide vane. The other part enters the right side of the compressor and enters the inside of the compressor after passing through the right guide vane. Or only enters the left side of the compressor. Afterwards, the low-temperature and low-pressure refrigerant gas is compressed by the compressor into a high-temperature and high-pressure refrigerant gas and enters the condenser, where the refrigerant is condensed from the high-temperature and high-pressure gas to a high-temperature and high-pressure liquid. Then enter the flasher, and separate the generated gas in the flasher. The gas enters the air supply port between the first and second level impellers on both sides of the compressor, and the air supply increases enthalpy. The remaining saturated refrigerant liquid is throttled to low temperature and low pressure refrigerant liquid, and enters the evaporator to complete evaporation and heat absorption. The compressor is a double cantilever four-impeller two-stage compression parallel structure. Guide vanes are set in front of the impeller inlet on both sides, including left guide vanes and right guide vanes. How to adjust and distribute the guide vanes on both sides to make the refrigeration unit reach a better operating state has become a key issue.

[0060] In addition, the refrigeration unit may also include other structures. Exemplarily, as shown in FIG1 , the refrigeration unit also includes a first electronic expansion valve (i.e., the electronic expansion valve 1 in FIG1 ) and a second electronic expansion valve (i.e., the electronic expansion valve 2 in FIG1 ), the first electronic expansion valve is arranged on the channel between the flasher and the evaporator, and the second electronic expansion valve is arranged on the channel between the condenser and the flasher. The first electronic expansion valve and the second electronic expansion valve play a throttling role. Specifically, the refrigerant in the condenser is condensed from high-temperature and high-pressure gas to high-temperature and high-pressure liquid, and after the first-level throttling of the first electronic expansion valve, it enters the flasher, and the gas generated in the first-level throttling process is separated in the flasher, and enters the air supply port between the first and second level impellers on both sides of the compressor, and the air is replenished to increase enthalpy. The remaining saturated refrigerant liquid is throttled to a low-temperature and low-pressure refrigerant liquid by the second-level throttling of the second electronic expansion valve, and enters the evaporator to complete evaporation and heat absorption.

[0061] Furthermore, in one embodiment, the refrigeration unit further comprises a first solenoid valve (i.e., solenoid valve 1 in FIG. 1 ), a second solenoid valve (i.e., solenoid valve 2 in FIG. 1 ), a third solenoid valve (i.e., solenoid valve 3 in FIG. 1 ) and a fourth solenoid valve (i.e., solenoid valve 4 in FIG. 1 ), wherein the first solenoid valve is arranged on the channel between the evaporator and the left guide vane, the second solenoid valve is arranged on the channel between the evaporator and the right guide vane, the third solenoid valve is arranged on the channel between the flasher and the left guide vane, and the fourth solenoid valve is arranged on the channel between the flasher and the right guide vane. Specifically, a part of the low-temperature and low-pressure refrigerant gas from the evaporator enters the left side of the compressor through the first solenoid valve according to the current capacity, and a part enters the right side of the compressor through the second solenoid valve. After the gas generated in the first-stage throttling process is separated in the flasher, the gas enters the air supply port between the first and second-stage impellers on both sides of the compressor through the third solenoid valve and the fourth solenoid valve, and the air supply increases the enthalpy. In this embodiment, the first solenoid valve, the second solenoid valve, the third solenoid valve and the fourth solenoid valve play the role of controlling the on-off of the passage, and the flow rate of the passage where the solenoid valve is located can also be adjusted by adjusting the opening of the solenoid valve.

[0062] It can be understood that the refrigeration unit control method can be executed by a controller inside the refrigeration unit, or by a terminal or server that is connected to the refrigeration unit. Among them, the terminal can be, but is not limited to, various personal computers, laptops, smart phones, tablet computers, Internet of Things devices and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart car devices, projection devices, etc. Portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The head-mounted device can be a virtual reality (VR) device, an augmented reality (AR) device, smart glasses, etc. The server can be an independent physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides cloud computing services.

[0063] In an exemplary embodiment, as shown in FIG2 , a refrigeration unit control method is provided, which is described by taking the method executed by a controller of the refrigeration unit as an example, and includes the following steps 202 to 208. Among them:

[0064] Step 202, obtaining the evaporation pressure of the evaporator and the condensation pressure of the condenser.

[0065] Among them, the evaporation pressure of the evaporator can be detected by the first pressure sensor (i.e., the pressure sensor 1 in Figure 1) and sent to the controller. The first pressure sensor is arranged on the evaporator. The first pressure sensor can continuously detect the evaporation pressure of the evaporator to obtain more detection data and improve the comprehensiveness of the detected data. The controller can continuously obtain the evaporation pressure from the first pressure sensor, or obtain the evaporation pressure at a preset time interval, or obtain the evaporation pressure when necessary. In addition, the first pressure sensor can also detect the evaporation pressure of the evaporator after receiving the start-up instruction from the controller, and then send it to the controller to realize on-demand detection, which is conducive to reducing the workload.

[0066] The condensing pressure of the condenser can be detected by the second pressure sensor (i.e., pressure sensor 2 in FIG. 1) and then sent to the controller. The second pressure sensor is arranged on the condenser. The second pressure sensor can continuously detect the condensing pressure of the condenser to obtain more detection data and improve the comprehensiveness of the detected data. The controller can continuously obtain the condensing pressure from the first pressure sensor, or obtain the condensing pressure at a preset time interval, or obtain the condensing pressure when necessary. In addition, the first pressure sensor can also detect the condensing pressure of the condenser after receiving the start-up instruction from the controller, and then send it to the controller to realize on-demand detection, which is conducive to reducing the workload.

[0067] Step 204 : determining a first power corresponding to the left guide vane and a second power corresponding to the right guide vane based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane.

[0068] Among them, the evaporation pressure can characterize the working state of the evaporator, and thus can also reflect the state related to the left guide vane set close to the evaporator. The opening of the left guide vane characterizes the position and state of the left guide vane, and thus reflects the state related to the left guide vane. The condensing pressure can characterize the working state of the condenser, and thus can also reflect the state related to the right guide vane set close to the condenser. The opening of the right guide vane characterizes the position and state of the right guide vane, and thus reflects the state related to the right guide vane. The opening of the left guide vane and the opening of the right guide vane can be obtained by the controller.

[0069] Thus, after relevant calculations are performed based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane, the first power corresponding to the left guide vane and the second power corresponding to the right guide vane can be obtained. Exemplarily, the first power corresponding to the left guide vane is determined based on the evaporation pressure, the condensation pressure, and the opening of the left guide vane, and the second power corresponding to the right guide vane is determined based on the evaporation pressure, the condensation pressure, and the opening of the left guide vane. It can be understood that in other embodiments, the first power and the second power can also be determined according to other methods, which are not limited here.

[0070] Step 206 : determining a target guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum.

[0071] Since the first power is a value related to the opening of the left guide vane, and the second power is a value related to the opening of the right guide vane, different first power values ​​can be calculated according to different opening values ​​of the left guide vane, and different second power values ​​can be calculated according to different opening values ​​of the right guide vane. The sum of different first power values ​​and different second power values ​​is exhaustively calculated to obtain the first power and the second power corresponding to the minimum sum of the first power and the second power, and then the target guide vane opening is determined according to the opening of the left guide vane corresponding to the first power and the opening of the right guide vane corresponding to the second power.

[0072] Exemplarily, the opening of the left guide vane and the opening of the right guide vane corresponding to the time when the sum of the first power and the second power is the smallest can be directly used as the target guide vane opening, or the target guide vane opening can be determined after comparing the opening of the left guide vane and the opening of the right guide vane corresponding to the time when the sum of the first power and the second power is the smallest or other processing is performed.

[0073] Step 208: Control the operation of the left guide vane and the right guide vane according to the target guide vane opening.

[0074] Among them, the target guide vane opening includes a target left guide vane opening and a target right guide vane opening. After determining the target guide vane opening, the working states of the left guide vane and the right guide vane are adjusted according to the target guide vane opening, so that the states of the left guide vane and the right guide vane meet the target guide vane opening. Since the target guide vane opening is obtained based on the opening of the left guide vane and the opening of the right guide vane corresponding to the minimum sum of the first power and the second power, it is a more optimal opening. Therefore, when the left guide vane and the right guide vane are controlled to work according to the target guide vane opening, the energy efficiency of the compressor can be made higher, which is beneficial to improving the working performance of the compressor.

[0075] In the above refrigeration unit control method, the evaporation pressure of the evaporator and the condensation pressure of the condenser are obtained, and the first power corresponding to the left guide vane and the second power corresponding to the right guide vane are determined based on the evaporation pressure and the condensation pressure. The target guide vane opening is determined according to the opening of the left guide vane and the opening of the right guide vane corresponding to the minimum sum of the first power and the second power, and the left guide vane and the right guide vane are controlled according to the target guide vane opening. Combined with the actual operating conditions of the refrigeration unit, the target guide vane adjustment opening is calculated to improve the energy efficiency after the guide vane is intervened, so as to improve the reliability of the energy regulation method of the refrigeration unit, thereby improving the working performance of the refrigeration unit.

[0076] In an exemplary embodiment, as shown in FIG3 , step 204 includes steps 302 to 308. Among them:

[0077] Step 302, determining the pressure ratio percentage based on the evaporation pressure, the condensation pressure and the rated pressure ratio.

[0078] If the evaporating pressure is P1, the condensing pressure is P2, and the rated pressure ratio is P0, then the pressure ratio P3=P2 / P1 can be calculated based on the evaporating pressure and the condensing pressure P2, and then the pressure ratio percentage p=P3 / P0 can be calculated.

[0079] Step 304, determining the volume flow percentage based on the evaporation pressure and the rated specific volume.

[0080] The evaporation pressure can reflect the current working condition of the compressor. Different evaporation pressures may correspond to different actual specific volumes. After determining the actual specific volume based on the evaporation pressure, combined with the rated specific volume, the volume flow percentage can be determined.

[0081] Step 306: Determine the first power corresponding to the left guide vane according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening of the left guide vane.

[0082] If the rated cooling capacity is Q0, the pressure ratio percentage is p, the volume flow percentage is qx, and the opening of the left guide vane is Y1, then the first power W1 corresponding to the left guide vane can be calculated according to the following formula (1):

[0083] (1)

[0084] Among them, a1, a2, ..., am and n are fitted according to the test data. The maximum sum of the powers of qx and p is n, and the sum of the powers decreases to 0. For example, when n=2, formula (1) is: .

[0085] Step 308, determining a second power corresponding to the right guide vane according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening of the right guide vane.

[0086] If the rated cooling capacity is Q0, the pressure ratio percentage is p, the volume flow percentage is qx, and the opening of the right guide vane is Y2, then the second power W2 corresponding to the right guide vane can be calculated according to the following formula (2):

[0087] (2)

[0088] Among them, a1, a2...am and n are fitted according to the test data.

[0089] It is understandable that the first power and the second power may also be obtained according to other calculation methods, which are not limited here.

[0090] In this embodiment, the pressure ratio percentage is determined based on the evaporating pressure, the condensing pressure and the rated pressure ratio, and the volume flow percentage is determined based on the evaporating pressure and the rated specific volume. Then, the first power corresponding to the left guide vane is determined according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening of the left guide vane. The second power corresponding to the right guide vane is determined according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening of the right guide vane. An optional method for calculating the first power and the second power is provided, and the calculated first power and second power are consistent with the current state of the refrigeration unit, which is convenient for subsequent determination of the target guide vane opening according to the first power and the second power, thereby accurately controlling the left guide vane and the right guide vane.

[0091] Exemplarily, in one embodiment, as shown in FIG4 , step 304 includes steps 402 to 406.

[0092] Step 402, determining the actual specific volume based on the evaporation pressure.

[0093] After obtaining the evaporation pressure, the corresponding evaporation temperature can be determined, and then the actual specific volume under the current working condition can be determined based on the preset correspondence between the evaporation temperature and the specific volume.

[0094] Step 404, determining the specific volume percentage according to the actual specific volume and the rated specific volume.

[0095] The specific volume percentage is the quotient of the actual specific volume and the rated specific volume. If the actual specific volume is R1 and the rated specific volume is R0, the specific volume percentage r = R1 / R0.

[0096] Step 406, determining the volume flow percentage according to the specific volume percentage and the opening of the left guide vane.

[0097] The volume flow percentage is the quotient of the opening of the left guide vane and the specific volume percentage. If the opening of the left guide vane is Y1 and the specific volume percentage is r, then the volume flow percentage qx = Y1 / r.

[0098] It is understandable that the volume flow percentage may also be obtained based on other calculations, which are not limited here.

[0099] In this embodiment, the actual specific volume is determined based on the evaporating pressure, the specific volume percentage is determined according to the actual specific volume and the rated specific volume, and the volume flow percentage is determined according to the specific volume percentage and the opening of the left guide vane. An optional method for calculating the volume flow percentage is provided, and the calculated volume flow percentage is consistent with the current state of the refrigeration unit, which facilitates improving the accuracy of the first power and the second power subsequently determined according to the volume flow percentage.

[0100] Exemplarily, in one embodiment, as shown in FIG5 , step 206 includes steps 502 to 506.

[0101] Step 502: determining an optimal guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum.

[0102] Since the first power is a value related to the opening of the left guide vane, and the second power is a value related to the opening of the right guide vane. Different values ​​of the first power can be calculated according to different values ​​of the opening of the left guide vane, and different values ​​of the second power can be calculated according to different values ​​of the opening of the right guide vane. The sum of different first power values ​​and different second power values ​​is exhaustively calculated to obtain the first power and the second power corresponding to the minimum sum of the first power and the second power, and then the optimal guide vane opening is determined according to the opening of the left guide vane corresponding to the first power and the opening of the right guide vane corresponding to the second power. Exemplarily, the opening of the left guide vane and the opening of the right guide vane corresponding to the minimum sum of the first power and the second power can be directly used as the optimal guide vane opening.

[0103] Step 504 : determining the minimum guide vane opening based on the evaporation pressure and the condensation pressure.

[0104] Among them, the minimum guide vane opening includes the minimum guide vane opening of the left guide vane and the minimum guide vane opening of the right guide vane. The method of determining the minimum guide vane opening based on the evaporation pressure and the condensing pressure is not the only one. For example, the pressure ratio percentage is first calculated based on the evaporation pressure and the condensing pressure, and then the minimum guide vane opening is calculated based on the pressure ratio percentage. For example, if the evaporation pressure is P1, the condensing pressure is P2, and the rated pressure ratio is P0, then the pressure ratio P3=P2 / P1 can be calculated based on the evaporation pressure and the condensing pressure P2, and then the pressure ratio percentage p=P3 / P0 is calculated.

[0105] The method for calculating the minimum guide vane opening (Y1+Y2) min / 2 is as follows:

[0106] (3)

[0107] Among them, p is the compression ratio percentage, and b1, b2, b3, b4, and b5 are fitted according to the test data.

[0108] Step 506: determine the target guide vane opening according to the optimal guide vane opening and the minimum guide vane opening.

[0109] After the optimal guide vane opening and the minimum guide vane opening are determined, the target guide vane opening can be determined according to the optimal guide vane opening and the minimum guide vane opening. For example, the target guide vane opening can be determined according to the optimal guide vane opening or the minimum guide vane opening, or the target guide vane opening can be determined after performing relevant calculations on the optimal guide vane opening or the minimum guide vane opening, and the specific method is not limited here.

[0110] In this embodiment, the optimal guide vane opening is determined based on the opening of the left guide vane and the opening of the right guide vane corresponding to the time when the sum of the first power and the second power is the smallest, the minimum guide vane opening is determined based on the evaporating pressure and the condensing pressure, and the target guide vane opening is determined based on the optimal guide vane opening and the minimum guide vane opening, so that the target guide vane opening is more in line with the actual operating conditions of the unit, which is beneficial to improving the working reliability of the refrigeration unit.

[0111] Further, when determining the target guide vane opening according to the optimal guide vane opening and the minimum guide vane opening, the target guide vane opening can be determined according to the magnitude relationship between the optimal guide vane opening and the minimum guide vane opening. Exemplarily, in one embodiment, as shown in FIG6 , step 506 includes step 602 and step 604 .

[0112] Step 602: When the optimal guide vane opening is greater than the minimum guide vane opening, determine the optimal guide vane opening as the target guide vane opening.

[0113] When the optimal guide vane opening is greater than the minimum guide vane opening, it means that if the openings of the left and right guide vanes are adjusted according to the optimal guide vane opening, the probability of unit surge is low, and on the basis of effective adjustment of the unit capacity, the stable operation of the unit can be guaranteed to a certain extent. Therefore, when the optimal guide vane opening is greater than the minimum guide vane opening, the optimal guide vane opening can be directly determined as the target guide vane opening.

[0114] Step 604 , when the optimal guide vane opening is less than the minimum guide vane opening, the optimal guide vane opening is updated based on the minimum guide vane opening and the specific volume percentage, and the updated optimal guide vane opening is determined as the target guide vane opening.

[0115] When the optimal guide vane opening is less than the minimum guide vane opening, it means that if the guide vane is adjusted according to the optimal guide vane opening as the target guide vane opening, surge will occur. Therefore, in this case, the optimal guide vane opening can be updated based on the minimum guide vane opening and the specific volume percentage, and the updated optimal guide vane opening is determined as the target guide vane opening.

[0116] Among them, the specific volume percentage is obtained based on the evaporation pressure. After obtaining the evaporation pressure, the corresponding evaporation temperature can be determined, and then the actual specific volume under the current working conditions can be determined based on the preset correspondence between the evaporation temperature and the specific volume. The specific volume percentage is the quotient of the actual specific volume and the rated specific volume. If the actual specific volume is R1 and the rated specific volume is R0, the specific volume percentage r=R1 / R0.

[0117] The method for updating the optimal guide vane opening based on the minimum guide vane opening and the specific volume percentage can be: adjust qx=(Y1+Y2)min / 2r, where (Y1+Y2)min / 2 is the minimum guide vane opening, r is the specific volume percentage, and obtain the updated qx, where qx ​​is the volume flow percentage.

[0118] Afterwards, the first power and the second power are calculated using the updated qx, and the updated optimal guide vane opening is determined by the opening of the left guide vane and the opening of the right guide vane corresponding to the minimum sum of the updated first power and the second power. The specific process can be referred to the above step of using the volume flow percentage to determine the first power and the second power, and then obtain the optimal guide vane opening, which will not be repeated here. After obtaining the updated optimal guide vane opening, the updated optimal guide vane opening is determined as the target guide vane opening.

[0119] In this embodiment, according to the different size relationships between the optimal guide vane opening and the minimum guide vane opening, different methods are used to determine the target guide vane opening. When the optimal guide vane opening is greater than the minimum guide vane opening, the optimal guide vane opening is determined as the target guide vane opening. When the optimal guide vane opening is less than the minimum guide vane opening, the optimal guide vane opening is updated based on the minimum guide vane opening and the specific volume percentage, and the updated optimal guide vane opening is determined as the target guide vane opening. The compressor is adjusted according to different target guide vane openings under different circumstances, which is conducive to optimizing the energy efficiency during the adjustment process.

[0120] In addition, in one embodiment, after step 604 and before step 208, the refrigeration unit control method further includes the step of controlling the opening of hot gas bypass.

[0121] Wherein, opening the hot gas bypass may include: bypassing the high-temperature gaseous refrigerant at the high-pressure end to the low-pressure end of the system, so that the system always maintains stable operation at a preset minimum return air pressure. Exemplarily, the implementation of opening the hot gas bypass may include: bypassing to the return air end or bypassing to the inlet of the evaporator.

[0122] In this embodiment, when the optimal guide vane opening is less than the minimum guide vane opening, the optimal guide vane openings on both sides are calculated in combination with the minimum guide vane opening, and hot gas bypass is intervened at the same time. The hot gas bypass is opened to supplement the part that exceeds the minimum guide vane opening, and then the left and right guide vanes are controlled to operate according to the target guide vane opening, so as to achieve the highest energy efficiency while achieving a wide operating range and realizing high energy efficiency under all operating conditions.

[0123] Exemplarily, in one embodiment, the refrigeration unit control method further includes the step of: controlling the flasher to supply air to the left guide vane and the right guide vane according to a ratio corresponding to the target guide vane opening.

[0124] Among them, the flash device is connected to the air supply port between the first and second impellers on both sides of the compressor in the compressor, and the gas can be passed into the air supply port between the first and second impellers on both sides of the compressor to replenish air and increase enthalpy.

[0125] The ratio corresponding to the target guide vane opening refers to the ratio between the opening of the left guide vane and the opening of the right guide vane corresponding to the target guide vane opening. For example, if the ratio between the opening of the left guide vane and the opening of the right guide vane corresponding to the target guide vane opening is 1:2, the air supply amount on the left and right sides of the compressor is also distributed in a ratio of 1:2, and the flasher is controlled to supply air to the left guide vane and the right guide vane according to the ratio of 1:2.

[0126] In this embodiment, after the target guide vane opening is calculated, the flasher is controlled to supply air to the left guide vane and the right guide vane according to the proportion corresponding to the target guide vane opening, and the air supply amount is synchronously distributed and adjusted according to the proportion of the guide vane opening on both sides, so as to achieve higher energy efficiency.

[0127] In an embodiment, as shown in FIG. 7 , before step 202 , the refrigeration unit control method further includes steps 702 and 704 .

[0128] Step 702: When it is determined that capacity adjustment is required, adjust the operating frequency of the compressor.

[0129] When it is determined that capacity adjustment is required, the operating frequency of the compressor is adjusted first before adjusting the guide vanes. Specifically, the operating frequency of the compressor can be adjusted by adjusting the motor speed in the compressor. It can be understood that the operating frequency of the compressor can be adjusted multiple times, and each time the operating frequency is reduced, the refrigeration unit is operated according to the reduced operating frequency.

[0130] Step 704: If the operating frequency still does not meet the capacity requirement after being adjusted to the minimum value, execute step 202.

[0131] After the operating frequency is adjusted to the minimum value, the capacity of the refrigeration unit is obtained. If the capacity requirement is still not met at this time, it means that the frequency adjustment alone cannot meet the adjustment demand. In this case, step 202 and subsequent steps are performed, combined with the opening adjustment of the left guide vane and the right guide vane of the compressor, to better improve the operating state of the refrigeration unit.

[0132] In this embodiment, when it is determined that capacity adjustment is required, variable frequency adjustment is prioritized to reduce capacity. When the current frequency reaches the minimum value and still does not meet the capacity requirement, guide vane adjustment is performed to improve the operating reliability of the refrigeration unit.

[0133] There is not only one way to determine whether capacity adjustment is needed. For example, in one embodiment, the refrigeration unit control method also includes the steps of: obtaining the chilled water outlet temperature of the evaporator; and determining that capacity adjustment is needed when the chilled water outlet temperature is greater than a preset temperature threshold.

[0134] The chilled water outlet temperature of the evaporator can be detected by a temperature sensor arranged at the outlet of the evaporator. The temperature sensor is connected to the controller and can send the detected chilled water outlet temperature of the evaporator to the controller.

[0135] After the controller obtains the chilled water outlet temperature, it compares it with the preset temperature threshold. When the chilled water outlet temperature is greater than the preset temperature threshold, it indicates that capacity adjustment is required at this time. In an extensible manner, the controller may also determine that capacity adjustment is required when the chilled water outlet temperature is greater than the preset temperature threshold by a certain amount. Alternatively, the controller may also determine that capacity adjustment is required when the chilled water outlet temperature is greater than the preset temperature threshold for a duration greater than the preset duration, which can effectively reduce the occurrence of false detection.

[0136] In this embodiment, the chilled water outlet temperature of the evaporator is obtained, and when the chilled water outlet temperature is greater than a preset temperature threshold, it is determined that capacity adjustment is required. An implementable method for determining whether capacity adjustment is required is provided, which facilitates capacity adjustment on demand.

[0137] In order to better understand the above embodiment, a detailed explanation is given below in conjunction with a specific embodiment. In one embodiment, as shown in FIG1 , the refrigeration unit includes a compressor, an evaporator, a condenser, a flasher, a primary throttling electronic expansion valve 1, a secondary throttling electronic expansion valve 2, a solenoid valve 1 for controlling air intake on the left side of the compressor, a solenoid valve 2 for controlling air intake on the right side of the compressor, a solenoid valve 3 for controlling air replenishment in the middle of the compression on the left side of the compressor, a solenoid valve 4 for controlling air replenishment in the middle of the compression on the right side of the compressor, a pressure sensor 1 for detecting evaporation pressure, and a pressure sensor 2 for detecting condensation pressure.

[0138] The low-temperature and low-pressure refrigerant gas coming out of the evaporator enters the left side of the compressor through solenoid valve 1, enters the right side of the compressor through solenoid valve 2, or only enters the left side of the compressor according to the current capacity. After being compressed into high-temperature and high-pressure refrigerant gas by the compressor, it enters the condenser, and the refrigerant in the condenser is condensed from high-temperature and high-pressure gas to high-temperature and high-pressure liquid. After the first-level throttling of the electronic expansion valve 1, it enters the flasher, and the gas generated in the first-level throttling process is separated in the flasher. It enters the air supply port between the first and second level impellers on both sides of the compressor through solenoid valve 3 or solenoid valve 4 to replenish air and increase enthalpy. The remaining saturated refrigerant liquid is throttled to a low-temperature and low-pressure refrigerant liquid through the second level of the electronic expansion valve 2, and enters the evaporator to complete evaporation and heat absorption.

[0139] As shown in FIG8 , the steps of the refrigeration unit control method include:

[0140] The detected evaporation pressure is P1, the condensing pressure is P2, the rated pressure ratio is set to P0, the pressure ratio P3=P2 / P1, and the pressure ratio percentage p=P3 / P0.

[0141] When the chilled water outlet temperature is higher than the set value by a certain amount, which can be set, it is determined that capacity adjustment is required. When adjusting capacity, variable frequency adjustment is given priority. The motor speed is adjusted by adjusting the frequency converter frequency, and then the impeller speed is adjusted. When the current frequency of the compressor reaches the minimum value, the guide vane adjustment is intervened. The compressor has left and right guide vanes. The left guide vane opening is set to Y1, the right guide vane opening is set to Y2, the rated specific volume is R0, and the rated cooling capacity is Q0. According to the evaporation pressure P1 of the current working condition corresponding to the evaporation temperature, the specific volume R1 at the evaporation temperature is obtained by looking up the table, the specific volume percentage r=R1 / R0, and the volume flow percentage qx=Y1 / r. Calculate the power W1 and W2 according to the following formula, substitute Y1 into the following formula to obtain W1, substitute Y2 into the following formula (4) to obtain W2, and take W1+W2 as the minimum to obtain the optimal value of Y1&Y2 under the current working condition, that is, the optimal guide vane opening:

[0142] (4)

[0143] Wherein, W can be W1 or W2, p is the pressure ratio percentage, qx is the volume flow percentage, and a1, a2, ..., am and n are fitted according to the test data.

[0144] The guide vane is adjusted according to the optimal Y1&Y2 as the target opening, and the air supply on the left and right sides is also distributed according to the ratio of Y1:Y2.

[0145] Calculate the minimum guide vane opening:

[0146] (5)

[0147] ——b1, b2, b3, b4, b5 are fitted according to the test data. It can be understood that the minimum guide vane opening can be calculated by equation (5) obtained by fitting the unit surge curve model. When the optimal Y1, Y2 is greater than or equal to the minimum Y1, Y2, adjust according to the optimal Y1, Y2; when the optimal Y1, Y2 is less than the minimum Y1, Y2, adjust according to the minimum Y1, Y2, and then combine with hot gas bypass.

[0148] When the guide vane opening (Y1+Y2) / 2 is less than the minimum value calculated above, adjust qx=(Y1+Y2)min / 2r, and calculate the optimal Y1' and Y2' by combining the power calculation formula and the minimum guide vane opening formula. Set Y1' and Y2' as the target guide vane opening. For the part exceeding the minimum guide vane, open the hot gas bypass to make up for it.

[0149] This method gives priority to adjusting the frequency. After reaching the minimum frequency, the guide vanes are intervened, and the optimal guide vane opening on both sides is calculated by the formula, which is used as the target guide vane opening adjustment. At the same time, the air supply volume is synchronously distributed and adjusted according to the guide vane opening ratio on both sides to achieve the highest energy efficiency. After reaching the minimum guide vane opening, the optimal guide vane opening on both sides is calculated in combination with the minimum guide vane opening, and hot gas bypass is intervened at the same time, achieving a wide operating range while achieving the highest energy efficiency, and achieving high energy efficiency under all operating conditions.

[0150] Therefore, by calculating the optimal guide vane adjustment opening, the energy efficiency after the guide vane is introduced can be improved to ensure that the energy efficiency is optimal during the capacity regulation process; at the same time, the minimum guide vane opening is calculated taking surge into consideration, and when it is less than the minimum guide vane opening, it is combined with hot gas bypass regulation to achieve a wide operating range while taking into account high energy efficiency under all operating conditions.

[0151] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0152] Based on the same inventive concept, the embodiment of the present application also provides a refrigeration unit control device for implementing the refrigeration unit control method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more refrigeration unit control device embodiments provided below can refer to the limitations of the refrigeration unit control method above, and will not be repeated here.

[0153] In an exemplary embodiment, a refrigeration unit control device is provided, wherein the refrigeration unit comprises an evaporator, a compressor, a condenser and a flasher which are sequentially connected, the flasher is also connected to the evaporator and the compressor, the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided; as shown in FIG9 , the refrigeration unit control device comprises: a pressure acquisition module 902, a power determination module 904, an opening determination module 906 and an opening adjustment module 908, wherein:

[0154] A pressure acquisition module 902 is used to acquire the evaporation pressure of the evaporator and the condensation pressure of the condenser;

[0155] A power determination module 904, configured to determine a first power corresponding to the left guide vane and a second power corresponding to the right guide vane based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane;

[0156] An opening determination module 906, configured to determine a target guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum;

[0157] The opening adjustment module 908 is used to control the operation of the left guide vane and the right guide vane according to the target guide vane opening.

[0158] In one embodiment, the power determination module is also used to determine the pressure ratio percentage based on the evaporating pressure, the condensing pressure and the rated pressure ratio; determine the volume flow percentage based on the evaporating pressure and the rated specific volume; determine the first power corresponding to the left guide vane according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening of the left guide vane; determine the second power corresponding to the right guide vane according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening of the right guide vane.

[0159] In one embodiment, the power determination module is further configured to determine the actual specific volume based on the evaporation pressure; determine the specific volume percentage according to the actual specific volume and the rated specific volume; and determine the volume flow percentage according to the specific volume percentage and the opening of the left guide vane.

[0160] In one embodiment, the opening determination module is also used to determine the optimal guide vane opening based on the opening of the left guide vane and the opening of the right guide vane corresponding to the time when the sum of the first power and the second power is the minimum; determine the minimum guide vane opening based on the evaporation pressure and the condensation pressure; determine the target guide vane opening based on the optimal guide vane opening and the minimum guide vane opening.

[0161] In one embodiment, the opening determination module is also used to determine the optimal guide vane opening as the target guide vane opening when the optimal guide vane opening is greater than the minimum guide vane opening; when the optimal guide vane opening is less than the minimum guide vane opening, update the optimal guide vane opening based on the minimum guide vane opening and the specific volume percentage, and determine the updated optimal guide vane opening as the target guide vane opening; the specific volume percentage is obtained based on the evaporation pressure.

[0162] In one embodiment, the refrigeration unit control device also includes a hot gas bypass module, which is used to update the optimal guide vane opening based on the minimum guide vane opening and the specific volume percentage when the opening determination module finds that the optimal guide vane opening is less than the minimum guide vane opening, and after determining that the updated optimal guide vane opening is the target guide vane opening, the opening adjustment module controls the opening of the hot gas bypass before controlling the left guide vane and the right guide vane to operate according to the target guide vane opening.

[0163] In one embodiment, the refrigeration unit control device further includes an air supply module, which is used to control the flasher to supply air to the left guide vane and the right guide vane according to a ratio corresponding to the target guide vane opening.

[0164] In one embodiment, the refrigeration unit control device also includes a frequency modulation module, which is used to adjust the operating frequency of the compressor when it is determined that capacity adjustment is required before the pressure acquisition module acquires the evaporating pressure of the evaporator and the condensing pressure of the condenser; when the operating frequency is adjusted to the minimum value and still does not meet the capacity requirement, the pressure acquisition module acquires the evaporating pressure of the evaporator and the condensing pressure of the condenser.

[0165] In one embodiment, the refrigeration unit control device further includes a capacity adjustment determination module, which is used to obtain the chilled water outlet temperature of the evaporator; when the chilled water outlet temperature is greater than a preset temperature threshold, it is determined that capacity adjustment is required.

[0166] Each module in the above refrigeration unit control device can be implemented in whole or in part by software, hardware or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to each module.

[0167] In one embodiment, a refrigeration unit control device is provided, the refrigeration unit includes an evaporator, a compressor, a condenser and a flasher which are connected in sequence, the flasher is also connected to the evaporator and the compressor, the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided. The refrigeration unit control device includes a first pressure sensor, a second pressure sensor and a controller, the first pressure sensor is provided on the evaporator, the second pressure sensor is provided on the condenser, and the first pressure sensor and the second pressure sensor are both connected to the controller; the first pressure sensor is used to detect the evaporation pressure of the evaporator and send it to the controller; the second pressure sensor is used to detect the condensation pressure of the condenser and send it to the controller; the controller is used to control the refrigeration unit according to the method of any of the above embodiments.

[0168] The evaporation pressure of the evaporator can be detected by the first pressure sensor and then sent to the controller. The first pressure sensor is arranged on the evaporator. The first pressure sensor can continuously detect the evaporation pressure of the evaporator to obtain more detection data and improve the comprehensiveness of the detected data. The controller can continuously obtain the evaporation pressure from the first pressure sensor, or obtain the evaporation pressure at a preset time interval, or obtain the evaporation pressure when necessary. In addition, the first pressure sensor can also detect the evaporation pressure of the evaporator after receiving the start instruction from the controller, and then send it to the controller to realize on-demand detection, which is conducive to reducing the workload.

[0169] The condensing pressure of the condenser can be detected by the second pressure sensor and then sent to the controller. The second pressure sensor is arranged on the condenser. The second pressure sensor can continuously detect the condensing pressure of the condenser to obtain more detection data and improve the comprehensiveness of the detected data. The controller can continuously obtain the condensing pressure from the first pressure sensor, or obtain the condensing pressure at a preset time interval, or obtain the condensing pressure when necessary. In addition, the first pressure sensor can also detect the condensing pressure of the condenser after receiving the start-up instruction from the controller, and then send it to the controller to realize on-demand detection, which is conducive to reducing the workload.

[0170] In this embodiment, combined with the actual operating conditions of the refrigeration unit, the target guide vane adjustment opening is calculated by the controller to improve the energy efficiency after the guide vanes are inserted, so as to improve the reliability of the energy regulation method of the refrigeration unit and thus improve the working performance of the refrigeration unit.

[0171] In one embodiment, a refrigeration system is provided, including a refrigeration unit and a refrigeration unit control device as described above. The basic structure of the refrigeration unit is: including an evaporator, a compressor, a condenser and a flasher which are connected in sequence, and the flasher is also connected to the evaporator and the compressor. The compressor is a double-cantilever four-impeller two-stage compression parallel structure, in which a left guide vane close to the evaporator and a right guide vane close to the condenser are provided. When the refrigeration unit is working, a part of the low-temperature and low-pressure refrigerant gas coming out of the evaporator enters the left side of the compressor according to the current capacity, and enters the compressor after passing through the left guide vane. The other part enters the right side of the compressor and enters the compressor after passing through the right guide vane. Or it only enters the left side of the compressor. After that, the low-temperature and low-pressure refrigerant gas is compressed into high-temperature and high-pressure refrigerant gas by the compressor and enters the condenser, and the refrigerant in the condenser is condensed from high-temperature and high-pressure gas to high-temperature and high-pressure liquid. Then it enters the flasher, and the generated gas is separated in the flasher. The gas enters the air supply port between the first and second impellers on both sides of the compressor, and the air supply increases enthalpy. The remaining saturated refrigerant liquid is throttled to a low-temperature and low-pressure refrigerant liquid, enters the evaporator, and completes evaporation and heat absorption. The compressor is a double-cantilever four-impeller two-stage compression parallel structure, and guide vanes are arranged in front of the impeller inlets on both sides, including left guide vanes and right guide vanes.

[0172] In addition, the refrigeration unit may also include other structures. Exemplarily, as shown in FIG1 , the refrigeration unit also includes a first electronic expansion valve and a second electronic expansion valve, the first electronic expansion valve is arranged on the channel between the flasher and the evaporator, and the second electronic expansion valve is arranged on the channel between the condenser and the flasher. The first electronic expansion valve and the second electronic expansion valve play a throttling role. Specifically, the refrigerant in the condenser is condensed from high-temperature and high-pressure gas to high-temperature and high-pressure liquid, and after the first-level throttling of the first electronic expansion valve, it enters the flasher, and the gas generated in the first-level throttling process is separated in the flasher, and enters the air supply port between the first and second level impellers on both sides of the compressor to increase enthalpy by supplying air, and the remaining saturated refrigerant liquid is throttled to a low-temperature and low-pressure refrigerant liquid by the second level of the second electronic expansion valve, and enters the evaporator to complete evaporation and heat absorption.

[0173] Furthermore, in one embodiment, as shown in FIG1 , the refrigeration unit further includes a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve, wherein the first solenoid valve is arranged on the channel between the evaporator and the left guide vane, the second solenoid valve is arranged on the channel between the evaporator and the right guide vane, the third solenoid valve is arranged on the channel between the flasher and the left guide vane, and the fourth solenoid valve is arranged on the channel between the flasher and the right guide vane. Specifically, a part of the low-temperature and low-pressure refrigerant gas from the evaporator enters the left side of the compressor through the first solenoid valve according to the current capacity, and a part enters the right side of the compressor through the second solenoid valve. After the gas generated in the first-stage throttling process is separated in the flasher, the gas enters the air supply port between the first and second impellers on both sides of the compressor through the third solenoid valve and the fourth solenoid valve, and the air supply increases the enthalpy. In this embodiment, the first solenoid valve, the second solenoid valve, the third solenoid valve and the fourth solenoid valve play the role of controlling the on-off of the passage, and the flow rate of the passage where the solenoid valve is located can also be adjusted by adjusting the opening of the solenoid valve.

[0174] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0175] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the present application. It should be noted that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A refrigeration unit control method, characterized in that: The refrigeration unit comprises an evaporator, a compressor, a condenser and a flasher which are connected in sequence, the flasher is also connected to the evaporator and the compressor, the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided; the method comprises: Obtaining the evaporation pressure of the evaporator and the condensation pressure of the condenser; Determining a first power corresponding to the left guide vane and a second power corresponding to the right guide vane based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane; determining a target guide vane opening according to an opening of the left guide vane and an opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum; The left guide vane and the right guide vane are controlled to operate according to the target guide vane opening.

2. The method according to claim 1, characterized in that The determining, based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane, a first power corresponding to the left guide vane and a second power corresponding to the right guide vane comprises: determining a pressure ratio percentage based on the evaporation pressure, the condensation pressure, and a rated pressure ratio; determining a volumetric flow rate percentage based on the evaporation pressure and the rated specific volume; Determining a first power corresponding to the left guide vane according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening of the left guide vane; A second power corresponding to the right guide vane is determined according to the rated cooling capacity, the pressure ratio percentage, the volume flow percentage and the opening degree of the right guide vane.

3. The method according to claim 2, characterized in that The determining of the volume flow percentage based on the evaporation pressure and the rated specific volume comprises: determining an actual specific volume based on the vaporization pressure; determining a specific volume percentage based on the actual specific volume and the rated specific volume; The volume flow percentage is determined according to the specific volume percentage and the opening of the left guide vane.

4. The method according to claim 1, characterized in that The determining the target guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum includes: Determining an optimal guide vane opening according to the opening of the left guide vane and the opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum; determining a minimum guide vane opening based on the evaporation pressure and the condensation pressure; A target guide vane opening is determined according to the optimal guide vane opening and the minimum guide vane opening.

5. The method according to claim 4, characterized in that Determining the target guide vane opening according to the optimal guide vane opening and the minimum guide vane opening includes: In a case where the optimal guide vane opening is greater than the minimum guide vane opening, determining the optimal guide vane opening as a target guide vane opening; In a case where the optimal guide vane opening is less than the minimum guide vane opening, the optimal guide vane opening is updated based on the minimum guide vane opening and the specific volume percentage, and the updated optimal guide vane opening is determined as the target guide vane opening; the specific volume percentage is obtained based on the evaporation pressure.

6. The method according to claim 5, characterized in that In the case where the optimal guide vane opening is less than the minimum guide vane opening, after the optimal guide vane opening is updated based on the minimum guide vane opening and the specific volume percentage, and the updated optimal guide vane opening is determined as the target guide vane opening, and before the left guide vane and the right guide vane are controlled to operate according to the target guide vane opening, the method further includes: Control opens the hot gas bypass.

7. The method according to claim 1, characterized in that The method further comprises: The flasher is controlled to supply air to the left guide vane and the right guide vane according to the ratio corresponding to the target guide vane opening.

8. The method according to claim 1, characterized in that: Before obtaining the evaporation pressure of the evaporator and the condensation pressure of the condenser, the method further includes: When it is determined that capacity adjustment is required, adjusting the operating frequency of the compressor; When the capacity requirement is still not met after the operating frequency is adjusted to the minimum value, the step of obtaining the evaporation pressure of the evaporator and the condensation pressure of the condenser is performed.

9. The method according to claim 8, characterized in that The method further comprises: Obtaining the chilled water outlet temperature of the evaporator; When the chilled water outlet temperature is greater than a preset temperature threshold, it is determined that capacity adjustment is required.

10. A refrigeration unit control device, characterized in that: The refrigeration unit comprises an evaporator, a compressor, a condenser and a flasher which are connected in sequence, wherein the flasher is also connected to the evaporator and the compressor, and the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided; the device comprises: A pressure acquisition module, used for acquiring the evaporation pressure of the evaporator and the condensation pressure of the condenser; a power determination module, configured to determine a first power corresponding to the left guide vane and a second power corresponding to the right guide vane based on the evaporation pressure, the condensation pressure, the opening of the left guide vane, and the opening of the right guide vane; an opening determination module, configured to determine a target guide vane opening according to an opening of the left guide vane and an opening of the right guide vane corresponding to when the sum of the first power and the second power is minimum; The opening adjustment module is used to control the operation of the left guide vane and the right guide vane according to the target guide vane opening.

11. A refrigeration unit control device, characterized in that: The refrigeration unit comprises an evaporator, a compressor, a condenser and a flasher which are connected in sequence, the flasher is also connected to the evaporator and the compressor, the compressor is a double-cantilever four-impeller two-stage compression parallel structure, wherein a left guide vane close to the evaporator and a right guide vane close to the condenser are provided; The refrigeration unit control device comprises a first pressure sensor, a second pressure sensor and a controller, the first pressure sensor is arranged on the evaporator, the second pressure sensor is arranged on the condenser, and the first pressure sensor and the second pressure sensor are both connected to the controller; The first pressure sensor is used to detect the evaporation pressure of the evaporator and send it to the controller; the second pressure sensor is used to detect the condensation pressure of the condenser and send it to the controller; the controller is used to control the refrigeration unit according to the method described in any one of claims 1-9.

12. A refrigeration system, characterized in that: It comprises a refrigeration unit and the refrigeration unit control device as claimed in claim 11.

13. The refrigeration system according to claim 12, characterized in that: The refrigeration unit further includes a first electronic expansion valve and a second electronic expansion valve, wherein the first electronic expansion valve is arranged on a channel between the flasher and the evaporator, and the second electronic expansion valve is arranged on a channel between the condenser and the flasher.

14. The refrigeration system according to claim 13, characterized in that: The refrigeration unit also includes a first solenoid valve, a second solenoid valve, a third solenoid valve and a fourth solenoid valve. The first solenoid valve is arranged on the channel between the evaporator and the left guide vane, the second solenoid valve is arranged on the channel between the evaporator and the right guide vane, the third solenoid valve is arranged on the channel between the flasher and the left guide vane, and the fourth solenoid valve is arranged on the channel between the flasher and the right guide vane.

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