Refrigeration unit control methods, devices, equipment and refrigeration systems

Abstract

This application relates to a refrigeration unit control method, apparatus, equipment, and refrigeration system. The refrigeration unit includes an evaporator, a compressor, a condenser, and a flash evaporator arranged sequentially. The flash evaporator is also connected to the evaporator and the compressor. The compressor is a double-cantilever, four-impeller, two-stage compression parallel structure, with a left guide vane near the evaporator and a right guide vane near the condenser. The refrigeration unit control method includes: acquiring 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 and the condensation pressure; determining a target guide vane opening based on the opening degree of the left and right guide vanes corresponding to the minimum sum of the first and second power; and controlling the operation of the left and right guide vanes according to the target guide vane opening. The performance of the refrigeration unit is improved by calculating and adjusting the target guide vane opening.

Description

Technical Field

[0001] This application relates to the field of refrigeration technology, and in particular to a refrigeration unit control method, apparatus, equipment and refrigeration system. Background Technology

[0002] Refrigeration units primarily function to refrigerate and regulate temperature, leading to their widespread application. Currently, R134a is used as a refrigerant in refrigeration units, but its global warming potential (GWP) is too high. In recent years, manufacturers have been searching for alternatives to R134a. R1233zd(E) refrigerant, with its advantages in ozone depletion potential (ODP) and global warming potential (GWP), as well as its high refrigeration efficiency, is gradually becoming a replacement for R134a and represents 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 stress on the balancing shaft system and coordinating the impeller size, the R1233zd(E) compressor for the large-capacity range is designed as a double-cantilever, four-impeller, two-stage compression parallel structure, with guide vanes installed before the impeller inlets on both sides. Under this structure, how to adjust the operating state of the refrigeration unit to better perform its function has become an urgent problem to be solved. Summary of the Invention

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

[0005] In a first aspect, this application provides a refrigeration unit control method. The refrigeration unit includes an evaporator, a compressor, a condenser, and a flash evaporator arranged sequentially. The flash evaporator 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 is provided near the evaporator and a right guide vane is provided near the condenser. The method includes:

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

[0007] Based on the evaporation pressure, the condensation pressure, the opening degree of the left guide vane and the opening degree of the right guide vane, the first power corresponding to the left guide vane and the second power corresponding to the right guide vane are determined.

[0008] The target guide vane opening is determined based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized.

[0009] The operation of the left and right guide vanes is controlled according to the target guide vane opening.

[0010] In one embodiment, 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, the condensation pressure, the opening degree of the left guide vane, and the opening degree of the right guide vane includes:

[0011] The pressure ratio percentage is determined based on the evaporation pressure, the condensation pressure, and the rated pressure ratio;

[0012] The volumetric flow rate percentage is determined based on the evaporation pressure and rated specific volume.

[0013] The first power corresponding to the left guide vane is determined based on the rated cooling capacity, the pressure ratio percentage, the volumetric flow rate percentage, and the opening degree of the left guide vane.

[0014] The second power corresponding to the right guide vane is determined based on the rated cooling capacity, the pressure ratio percentage, the volumetric flow rate percentage, and the opening degree of the right guide vane.

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

[0016] The actual specific volume is determined based on the evaporation pressure.

[0017] Determine the specific capacity percentage based on the actual specific capacity and the rated specific capacity;

[0018] The volumetric flow rate percentage is determined based on the specific volume percentage and the opening of the left guide vane.

[0019] In one embodiment, determining the target guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized includes:

[0020] The optimal guide vane opening is determined based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized.

[0021] The minimum guide vane opening is determined based on the evaporation pressure and the condensation pressure.

[0022] The target guide vane opening is determined based on the optimal guide vane opening and the minimum guide vane opening.

[0023] In one embodiment, determining the target guide vane opening based on the optimal guide vane opening and the minimum guide vane opening includes:

[0024] If 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.

[0025] 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 specific volume percentage is obtained based on the evaporation pressure.

[0026] In one embodiment, after updating the optimal guide vane opening based on the minimum guide vane opening and specific volume percentage when the optimal guide vane opening is less than the minimum guide vane opening, and determining the updated optimal guide vane opening as the target guide vane opening, before controlling the left and right guide vanes to operate according to the target guide vane opening, the method further includes:

[0027] Control the opening of the hot gas bypass.

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

[0029] The flash generator is controlled to replenish air to the left and right guide vanes 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] If it is determined that capacity adjustment is required, adjust the operating frequency of the compressor;

[0032] If 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 includes:

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

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

[0036] Secondly, this application also provides a refrigeration unit control device. The refrigeration unit includes an evaporator, a compressor, a condenser, and a flash evaporator arranged sequentially. The flash evaporator 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 is provided near the evaporator and a right guide vane is provided near the condenser. The device includes:

[0037] A pressure acquisition module is used to acquire the evaporation pressure of the evaporator and the condensation pressure of the condenser;

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

[0039] An opening determination module is used to determine a target guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized.

[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] Thirdly, this application also provides a refrigeration unit control device, the refrigeration unit including an evaporator, a compressor, a condenser and a flash evaporator arranged in sequence, the flash evaporator 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 is provided near the evaporator and a right guide vane is provided near the condenser;

[0042] The refrigeration unit control equipment includes a first pressure sensor, a second pressure sensor, and a controller. The first pressure sensor is located on the evaporator, the second pressure sensor is located on the condenser, and both the first pressure sensor and the second pressure sensor are 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] Fourthly, this 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, the first electronic expansion valve being disposed in the channel between the flash evaporator and the evaporator, and the second electronic expansion valve being disposed in the channel between the condenser and the flash evaporator.

[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 disposed in the channel between the evaporator and the left guide vane, the second solenoid valve is disposed in the channel between the evaporator and the right guide vane, the third solenoid valve is disposed in the channel between the flash evaporator and the left guide vane, and the fourth solenoid valve is disposed in the channel between the flash evaporator and the right guide vane.

[0047] The aforementioned refrigeration unit control method, device, equipment, and refrigeration system include a refrigeration unit comprising an evaporator, a compressor, a condenser, and a flash evaporator arranged sequentially. The flash evaporator is also connected to the evaporator and compressor. The compressor is a double-cantilever, four-impeller, two-stage compression parallel structure, with a left guide vane near the evaporator and a right guide vane near the condenser. The refrigeration unit control method includes: acquiring 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 and condensation pressures; determining the target guide vane opening based on the opening degree of the left and right guide vanes corresponding to the minimum sum of the first and second power; and controlling the operation of the left and right guide vanes according to the target guide vane opening. By calculating the target guide vane adjustment opening in conjunction with the actual operating conditions of the refrigeration unit, the energy efficiency after the guide vanes are intervened is improved, thereby enhancing the reliability of the refrigeration unit's energy regulation method and ultimately improving the refrigeration unit's performance. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the structure of the refrigeration unit in one embodiment;

[0050] Figure 2 This is a flowchart illustrating a refrigeration unit control method in one embodiment;

[0051] Figure 3 This is a flowchart illustrating the steps of determining the first power corresponding to the left guide vane and the second power corresponding to the right guide vane based on evaporation pressure, condensation pressure, the opening degree of the left guide vane, and the opening degree of the right guide vane in one embodiment.

[0052] Figure 4 This is a flowchart illustrating the steps for determining the volumetric flow rate percentage based on evaporation pressure and rated specific volume in one embodiment.

[0053] Figure 5 This is a flowchart illustrating the steps of determining the target guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized in one embodiment.

[0054] Figure 6 This is a flowchart illustrating the steps for determining the target guide vane opening based on the optimal and minimum guide vane openings in one embodiment.

[0055] Figure 7 This is a flowchart illustrating the refrigeration unit control method in another embodiment;

[0056] Figure 8 This is a flowchart illustrating the refrigeration unit control method in another embodiment;

[0057] Figure 9 This is a structural block diagram of the refrigeration unit control device in one embodiment. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0059] The refrigeration unit control method provided in this application embodiment is used to control a refrigeration unit. The refrigeration unit includes, but is not limited to, a water chiller unit. Figure 1 As shown, the basic structure of the refrigeration unit includes an evaporator, compressor, condenser, and flash evaporator connected in sequence. The flash evaporator is also connected to the evaporator and compressor. The compressor is a double-cantilever, four-impeller, two-stage, parallel compression structure, with a left guide vane near the evaporator and a right guide vane near the condenser. When the refrigeration unit is operating, a portion of the low-temperature, low-pressure refrigerant gas exiting the evaporator enters the left side of the compressor, passes through the left guide vane, and enters the compressor interior. The other portion enters the right side of the compressor, passes through the right guide vane, and enters the compressor interior. Alternatively, it may only enter the left side of the compressor. The low-temperature, low-pressure refrigerant gas is then compressed by the compressor into a high-temperature, high-pressure refrigerant gas, which then enters the condenser. In the condenser, the refrigerant condenses from a high-temperature, high-pressure gas into a high-temperature, high-pressure liquid. It then enters the flash evaporator, where the generated gas is separated. The gas enters the gas inlet between the first and second stage impellers on both sides of the compressor, where the enthalpy is increased. The remaining saturated refrigerant liquid is throttled into a low-temperature, low-pressure refrigerant liquid, which then enters the evaporator to complete evaporation and heat absorption. The compressor is a two-stage parallel compression structure with double cantilever and four impellers. Guide vanes are installed in front of the impeller inlets on both sides, including left and right guide vanes. How to adjust and distribute the guide vanes on both sides to enable the refrigeration unit to achieve better operating conditions has become a key issue.

[0060] In addition, the refrigeration unit may also include other structures. For example, such as... Figure 1 As shown, the refrigeration unit also includes a first electronic expansion valve (i.e., Figure 1 The electronic expansion valve 1) and the second electronic expansion valve (i.e. Figure 1The first electronic expansion valve (2) is located in the channel between the flash evaporator and the evaporator, and the second electronic expansion valve is located in the channel between the condenser and the flash evaporator. Both the first and second electronic expansion valves function as throttling valves. Specifically, in the condenser, the refrigerant condenses from a high-temperature, high-pressure gas into a high-temperature, high-pressure liquid. After being throttled by the first electronic expansion valve, it enters the flash evaporator. In the flash evaporator, the gas generated during the first-stage throttling process is separated and enters the gas injection port between the first and second stage impellers on both sides of the compressor, where the gas injection increases enthalpy. The remaining saturated refrigerant liquid is throttled by the second electronic expansion valve into a low-temperature, low-pressure refrigerant liquid, which then enters the evaporator to complete evaporation and heat absorption.

[0061] Furthermore, in one embodiment, the refrigeration unit also includes a first solenoid valve (i.e., Figure 1 Solenoid valve 1) and second solenoid valve (i.e. Figure 1 Solenoid valve 2), third solenoid valve (i.e. Figure 1 Solenoid valve 3) and the fourth solenoid valve (i.e. Figure 1 The four solenoid valves are configured as follows: First solenoid valve is located in the channel between the evaporator and the left guide vane; second solenoid valve is located in the channel between the evaporator and the right guide vane; third solenoid valve is located in the channel between the flash evaporator and the left guide vane; and fourth solenoid valve is located in the channel between the flash evaporator and the right guide vane. Specifically, the low-temperature, low-pressure refrigerant gas exiting the evaporator, depending on its current capacity, enters the left side of the compressor via the first solenoid valve and the right side via the second solenoid valve. After the gas generated during the first-stage throttling process is separated in the flash evaporator, the gas enters the gas injection port between the first and second stage impellers on both sides of the compressor via the third and fourth solenoid valves, where it is injected to increase enthalpy. In this embodiment, the first, second, third, and fourth solenoid valves control the opening and closing of the passages, and the flow rate in the passage where the solenoid valve is located can be adjusted by regulating the opening degree of the solenoid valves.

[0062] It is understandable that the control method for the refrigeration unit can be executed by the controller inside the refrigeration unit, or by a terminal or server that communicates with the refrigeration unit. The terminal can be, but is not limited to, various personal computers, laptops, smartphones, tablets, IoT devices, and portable wearable devices. IoT devices can include smart speakers, smart TVs, smart air conditioners, smart in-vehicle systems, and projection equipment. Portable wearable devices can include smartwatches, smart bracelets, and head-mounted displays. Head-mounted displays can be virtual reality (VR) devices, augmented reality (AR) devices, and smart glasses. The server can be a standalone physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services.

[0063] In one exemplary embodiment, such as Figure 2 As shown, a refrigeration unit control method is provided. Taking the execution of this method by the controller of the refrigeration unit as an example, it includes the following steps 202 to 208. Wherein:

[0064] Step 202: Obtain the evaporation pressure of the evaporator and the condensation pressure of the condenser.

[0065] The evaporation pressure of the evaporator can be determined by the first pressure sensor (i.e., Figure 1 The pressure sensor 1) detects the evaporation pressure and sends the data to the controller. The first pressure sensor is located on the evaporator. The first pressure sensor can continuously monitor the evaporation pressure of the evaporator to obtain more 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 preset time intervals, or obtain the evaporation pressure when needed. Furthermore, the first pressure sensor can also detect the evaporation pressure of the evaporator only after receiving a start command from the controller, and then send the data to the controller, to achieve on-demand monitoring and reduce workload.

[0066] The condensing pressure of the condenser can be measured by a second pressure sensor (i.e., Figure 1 After the pressure sensor 2 detects the pressure, it sends the data to the controller. The second pressure sensor is located on the condenser. The second pressure sensor can continuously monitor the condensing pressure of the condenser to obtain more data and improve the comprehensiveness of the data. The controller can continuously obtain the condensing pressure from the first pressure sensor, or obtain the condensing pressure at preset time intervals, or obtain the condensing pressure when needed. In addition, the first pressure sensor can also detect the condensing pressure of the condenser after receiving a start command from the controller, and then send the data to the controller to achieve on-demand monitoring, which helps to reduce the workload.

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

[0068] The evaporation pressure characterizes the evaporator's operating state, and thus reflects the state of the left guide vane located near the evaporator. The opening degree of the left guide vane characterizes its position and state, thus reflecting its state. Similarly, the condensation pressure characterizes the condenser's operating state, and thus reflects the state of the right guide vane located near the condenser. The opening degree of the right guide vane characterizes its position and state, thus reflecting its state. Both the left and right guide vane opening degrees can be obtained by the controller.

[0069] Therefore, based on the evaporation pressure, condensation pressure, and the opening degrees of the left and right guide vanes, relevant calculations can be performed to obtain the first power corresponding to the left guide vane and the second power corresponding to the right guide vane. For example, the first power corresponding to the left guide vane is determined based on the evaporation pressure, condensation pressure, and the opening degree of the left guide vane, and the second power corresponding to the right guide vane is determined based on the same factors. It is understood that in other embodiments, the first and second powers can also be determined in other ways, and this is not limited here.

[0070] Step 206: Determine the target guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized.

[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 values ​​of the first power can be calculated based on different opening values ​​of the left guide vane, and different values ​​of the second power can be calculated based on different opening values ​​of the right guide vane. By exhaustively calculating the sums of different first power values ​​and different second power values, the first power and second power corresponding to the minimum sum are obtained. Then, the target guide vane opening is determined based on the opening of the left guide vane corresponding to this first power and the opening of the right guide vane corresponding to this second power.

[0072] For example, the opening degree of the left guide vane and the opening degree of the right guide vane corresponding to the minimum sum of the first power and the second power can be directly used as the target guide vane opening degree. Alternatively, the target guide vane opening degree can be determined by comparing the opening degree of the left guide vane and the opening degree of the right guide vane corresponding to the minimum sum of the first power and the second power or by other processing.

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

[0074] The target guide vane opening includes the target left guide vane opening and the target right guide vane opening. After determining the target guide vane opening, the operating states of the left and right guide vanes are adjusted according to the target guide vane opening to ensure that the states of the left and right guide vanes conform to the target guide vane opening. Since the target guide vane opening is obtained based on the opening of the left and right guide vanes corresponding to the minimum sum of the first and second power, it is a relatively optimal opening. Therefore, controlling the operation of the left and right guide vanes according to the target guide vane opening can result in higher compressor energy efficiency and improve compressor performance.

[0075] In the aforementioned refrigeration unit control method, the evaporation pressure of the evaporator and the condensation pressure of the condenser are obtained. Based on these pressures, the first power corresponding to the left guide vane and the second power corresponding to the right guide vane are determined. The target guide vane opening is determined based on the opening degree of the left and right guide vanes corresponding to the minimum sum of the first and second power. The operation of the left and right guide vanes is controlled according to the target guide vane opening. By calculating the target guide vane adjustment opening and considering the actual operating conditions of the refrigeration unit, the energy efficiency after guide vane intervention is improved, thereby enhancing the reliability of the refrigeration unit's energy regulation method and ultimately improving the refrigeration unit's performance.

[0076] In one exemplary embodiment, such as Figure 3 As shown, step 204 includes steps 302 to 308. Wherein:

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

[0078] If the evaporation pressure is P1, the condensation 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 condensation pressure P2, and then the pressure ratio percentage p = P3 / P0 can be calculated.

[0079] Step 304: Determine the volumetric flow rate percentage based on the evaporation pressure and rated specific volume.

[0080] Evaporation pressure reflects the current operating condition of the compressor, and different evaporation pressures may correspond to different actual specific volumes. After determining the actual specific volume based on the evaporation pressure, the volumetric flow rate percentage can be determined by combining it with the rated specific volume.

[0081] Step 306: Determine the first power corresponding to the left guide vane based on the rated cooling capacity, pressure ratio percentage, volumetric flow rate percentage, and the opening degree of the left guide vane.

[0082] If the rated cooling capacity is Q0, the pressure ratio percentage is p, the volumetric flow rate 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] Where a1, a2...am and n are fitted from the test data. The maximum sum of powers of qx and p is n, and the sum of powers decreases to 0. For example, when n=2, formula (1) is: .

[0085] Step 308: Determine the second power corresponding to the right guide vane based on the rated cooling capacity, pressure ratio percentage, volumetric flow rate percentage, and the opening degree of the right guide vane.

[0086] If the rated cooling capacity is Q0, the pressure ratio percentage is p, the volumetric flow rate 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 derived from the test data.

[0089] It is understandable that the first and second powers can also be obtained using other calculation methods, and no limitation is made here.

[0090] In this embodiment, the pressure ratio percentage is determined based on the evaporation pressure, condensation pressure, and rated pressure ratio, and the volumetric flow rate percentage is determined based on the evaporation pressure and rated specific volume. Then, the first power corresponding to the left guide vane is determined based on the rated cooling capacity, pressure ratio percentage, volumetric flow rate percentage, and the opening degree of the left guide vane. The second power corresponding to the right guide vane is determined based on the rated cooling capacity, pressure ratio percentage, volumetric flow rate percentage, and the opening degree of the right guide vane. This provides an optional method for calculating the first and second powers, and the calculated first and second powers conform to the current state of the refrigeration unit, which facilitates the subsequent determination of the target guide vane opening based on the first and second powers, thereby enabling accurate control of the left and right guide vanes.

[0091] Exemplarily, in one embodiment, such as Figure 4 As shown, step 304 includes steps 402 to 406. Wherein,

[0092] Step 402: Determine the actual specific volume based on the evaporation pressure.

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

[0094] Step 404: Determine the specific capacity percentage based on the actual specific capacity and the rated specific capacity.

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

[0096] Step 406: Determine the volumetric flow rate percentage based on the specific volume percentage and the opening of the left guide vane.

[0097] The volumetric flow rate 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 volumetric flow rate percentage qx = Y1 / r.

[0098] It is understandable that the volumetric flow rate percentage can also be obtained from other calculations, and no specific limit is imposed here.

[0099] In this embodiment, the actual specific volume is determined based on the evaporation pressure, the specific volume percentage is determined based on the actual specific volume and the rated specific volume, and the volumetric flow rate percentage is determined based on the specific volume percentage and the opening of the left guide vane. This provides an optional method for calculating the volumetric flow rate percentage, and the calculated volumetric flow rate percentage conforms to the current state of the refrigeration unit, which facilitates improving the accuracy of the first power and second power determined subsequently based on the volumetric flow rate percentage.

[0100] Exemplarily, in one embodiment, such as Figure 5 As shown, step 206 includes steps 502 to 506. Wherein,

[0101] Step 502: Determine the optimal guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized.

[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 based on different opening values ​​of the left guide vane, and different values ​​of the second power can be calculated based on different opening values ​​of the right guide vane. By exhaustively calculating the sums of different first power values ​​and different second power values, the first power and second power corresponding to the minimum sum of the first power and second power are obtained. Then, the optimal guide vane opening is determined based on 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. For example, the openings of the left and right guide vanes corresponding to the minimum sum of the first power and second power can be directly used as the optimal guide vane opening.

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

[0104] The minimum guide vane opening includes both the minimum guide vane opening of the left and right guide vanes. The method for determining the minimum guide vane opening based on the evaporation and condensation pressures is not unique. For example, the pressure ratio percentage can be calculated first based on the evaporation and condensation pressures, and then the minimum guide vane opening can be calculated based on the pressure ratio percentage. For instance, if the evaporation pressure is P1, the condensation pressure is P2, and the rated pressure ratio is P0, then the pressure ratio P3 = P2 / P1 can be calculated based on the evaporation and condensation pressures P2, and thus the pressure ratio percentage p = P3 / P0 can be calculated.

[0105] The method for calculating the minimum guide vane opening (Y1+Y2)min / 2 is as follows (3):

[0106] (3)

[0107] Where p is the pressure ratio percentage, and b1, b2, b3, b4, and b5 are derived from the test data.

[0108] Step 506: Determine the target guide vane opening based on the optimal guide vane opening and the minimum guide vane opening.

[0109] Once the optimal and minimum guide vane openings are determined, the target guide vane opening can be determined based on these two openings. For example, the target guide vane opening can be determined from either the optimal or minimum opening, or it can be determined by performing relevant calculations on either the optimal or minimum opening. 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 right guide vane when the sum of the first power and the second power is minimized. The minimum guide vane opening is determined based on the evaporation pressure and the condensation pressure. 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 conducive to improving the working reliability of the refrigeration unit.

[0111] Furthermore, when determining the target guide vane opening based on the optimal and minimum guide vane openings, the target guide vane opening can be determined according to the relationship between the optimal and minimum guide vane openings. For example, in one embodiment, such as... Figure 6 As shown, step 506 includes steps 602 and 604.

[0112] Step 602: If 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 indicates that adjusting the openings of the left and right guide vanes according to the optimal opening will result in a lower probability of unit surge. This effectively regulates the unit's capacity and, to a certain extent, ensures stable unit operation. 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, 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.

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

[0116] The specific volume percentage is derived from the evaporation pressure. After obtaining the evaporation pressure, the corresponding evaporation temperature can be determined. Then, based on the preset correspondence between evaporation temperature and specific volume, the actual specific volume under the current operating conditions can be determined. 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, then 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 as follows: Adjust qx=(Y1+Y2)min / 2r, where (Y1+Y2)min / 2 is the minimum guide vane opening and r is the specific volume percentage, to obtain the updated qx, where qx ​​is the volumetric flow rate percentage.

[0118] Next, the first power and the second power are calculated using the updated qx. 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, are used to determine the updated optimal guide vane opening. The specific process can be found in the steps above for determining the first power and the second power using the volumetric flow rate percentage, and then obtaining 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, the target guide vane opening is determined using different methods depending on the relationship between the optimal and minimum guide vane openings. 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. This allows the compressor to be adjusted according to different target guide vane openings under different conditions, which is beneficial for optimizing 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 the hot gas bypass.

[0121] Enabling hot gas bypass can 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 gas pressure. For example, enabling hot gas bypass can be achieved by bypassing to the return gas end or bypassing to the evaporator inlet.

[0122] In this embodiment, when the optimal guide vane opening is less than the minimum guide vane opening, the optimal opening of both guide vanes is calculated by combining the minimum guide vane opening. At the same time, hot gas bypass is introduced. For the part exceeding the minimum guide vane opening, hot gas bypass is opened to make up the difference. Then, the left and right guide vanes are controlled to work according to the target guide vane opening, so as to achieve the highest energy efficiency while achieving a wide operating range, and to achieve high energy efficiency under all operating conditions.

[0123] For example, in one embodiment, the refrigeration unit control method further includes the step of: controlling the flash generator to replenish air to the left and right guide vanes according to the proportional control of the target guide vane opening.

[0124] The flash generator connects to the gas inlet between the first and second stage impellers on both sides of the compressor, allowing gas to be introduced into the gas inlet between the first and second stage impellers on both sides of the compressor to 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, then the air supply volume on the left and right sides of the compressor is also distributed in a 1:2 ratio, and the flash evaporator is controlled to supply air to the left and right guide vanes according to the 1:2 ratio.

[0126] In this embodiment, after calculating the target guide vane opening, the flash generator is controlled to replenish air to the left and right guide vanes according to the ratio corresponding to the target guide vane opening. The replenishment amount is synchronously distributed and adjusted according to the ratio of the opening of the two guide vanes to achieve higher energy efficiency.

[0127] In a scalable embodiment, such as Figure 7 As shown, before step 202, the refrigeration unit control method also includes steps 702 and 704.

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

[0129] When capacity adjustment is determined to be necessary, the compressor's operating frequency should be adjusted first, before adjusting the guide vanes. Specifically, the compressor's operating frequency can be adjusted by changing the speed of the motor within the compressor. It can be understood that the compressor's operating frequency can be adjusted multiple times, with each adjustment lowering the operating frequency so that the refrigeration unit operates according to the reduced frequency.

[0130] Step 704: If the capacity requirement is still not met after adjusting the operating frequency to the minimum value, proceed to step 202.

[0131] After adjusting the operating frequency to its minimum value, obtain the capacity of the refrigeration unit. If the capacity requirement is still not met, it indicates that frequency adjustment alone cannot meet the adjustment needs. In this case, execute step 202 and subsequent steps, combining the adjustment of the opening degree of the left and right guide vanes of the compressor to better improve the operating status of the refrigeration unit.

[0132] In this embodiment, when it is determined that capacity adjustment is required, frequency conversion adjustment is prioritized to reduce capacity. If the capacity requirement is still not met after the current frequency reaches its minimum value, guide vane adjustment is intervened to improve the working reliability of the refrigeration unit.

[0133] There is no single way to determine whether capacity adjustment is needed. For example, in one embodiment, the chiller control method further includes the steps of: obtaining the chilled water outlet temperature of the evaporator; and determining that capacity adjustment is needed if 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 installed 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 acquiring the chilled water outlet temperature, the controller compares it with a preset temperature threshold. If the chilled water outlet temperature exceeds the preset temperature threshold, it indicates that capacity adjustment is required. Extendably, the controller can also determine that capacity adjustment is required if the chilled water outlet temperature exceeds the preset temperature threshold by a certain amount. Alternatively, the controller can determine that capacity adjustment is required if the duration of the chilled water outlet temperature exceeding the preset temperature threshold is greater than a preset duration, effectively reducing false detections.

[0136] In this embodiment, the chilled water outlet temperature of the evaporator is obtained. If the chilled water outlet temperature is higher than a preset temperature threshold, it is determined that capacity adjustment is required. This provides an implementation method for determining whether capacity adjustment is needed, facilitating on-demand capacity adjustment.

[0137] To better understand the above embodiments, a detailed explanation is provided below with reference to a specific embodiment. In one embodiment, as follows... Figure 1 As shown, the refrigeration unit includes a compressor, evaporator, condenser, flash evaporator, a primary throttling electronic expansion valve 1, a secondary throttling electronic expansion valve 2, a solenoid valve 1 controlling the left side intake of the compressor, a solenoid valve 2 controlling the right side intake of the compressor, a solenoid valve 3 controlling the intermediate gas injection on the left side of the compressor, a solenoid valve 4 controlling the intermediate gas injection 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, low-pressure refrigerant gas exiting the evaporator, depending on its current capacity, enters the left side of the compressor via solenoid valve 1, the right side via solenoid valve 2, or only the left side. After being compressed into high-temperature, high-pressure refrigerant gas by the compressor, it enters the condenser, where the refrigerant condenses from a high-temperature, high-pressure gas into a high-temperature, high-pressure liquid. After first-stage throttling by electronic expansion valve 1, it enters the flash evaporator, where the gas generated during the first-stage throttling process is separated. It then enters the gas injection port between the first and second stage impellers on both sides of the compressor via solenoid valve 3 or solenoid valve 4, where it is injected to increase enthalpy. The remaining saturated refrigerant liquid undergoes second-stage throttling by electronic expansion valve 2 to become a low-temperature, low-pressure refrigerant liquid, which then enters the evaporator to complete evaporation and heat absorption.

[0139] like Figure 8 As shown, the steps of the refrigeration unit control method include:

[0140] The evaporation pressure is measured as P1, the condensation pressure as P2, the rated pressure ratio is set as 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, and the set value is certain, it is determined that capacity adjustment is required. When adjusting the capacity, frequency conversion adjustment is given priority. The motor speed is adjusted by adjusting the frequency of the frequency converter, and then the impeller speed is adjusted. When the current frequency of the compressor reaches the minimum value, guide vane adjustment is intervened. The compressor has guide vanes on both the left and right sides. The opening degree of the left guide vane is set as Y1, the opening degree of the right guide vane is set as Y2, the rated specific capacity is R0, and the rated cooling capacity is Q0. According to the evaporation pressure P1 of the current working condition, the evaporation temperature is corresponding to the specific capacity R1 at the evaporation temperature. The specific capacity percentage r = R1 / R0, and the volumetric flow rate percentage qx = Y1 / r are obtained by referring to the table. The power W1 and W2 are calculated according to the following formulas. Y1 is substituted into the following formula to obtain W1, and Y2 is substituted into the following formula (4) to obtain W2. The optimal value of Y1 & Y2 under the current working condition is obtained by minimizing W1 + W2, that is, the optimal guide vane opening:

[0142] (4)

[0143] Where W can be W1 or W2, p is the pressure ratio percentage, qx is the volumetric flow rate percentage, and a1, a2...am and n are fitted from the test data.

[0144] The guide vanes are adjusted according to the optimal opening of Y1 & Y2, and the supplementary air volume on the left and right sides is also distributed according to the Y1:Y2 ratio.

[0145] Calculate the minimum guide vane opening:

[0146] (5)

[0147] — b1, b2, b3, b4, and b5 are derived from 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 and Y2 are greater than or equal to the minimum Y1 and Y2, the adjustment is based on the optimal Y1 and Y2; when the optimal Y1 and Y2 are less than the minimum Y1 and Y2, the adjustment is based on the minimum Y1 and Y2, combined 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 calculation formula. Set Y1' and Y2' as the target guide vane opening. For the part exceeding the minimum guide vane opening, open the hot gas bypass to make up for it.

[0149] This method prioritizes frequency adjustment. Once the minimum frequency is reached, the guide vanes are introduced. The optimal opening degree of both guide vanes is calculated using a formula and used as the target guide vane opening for adjustment. Simultaneously, the supplementary air volume is distributed and adjusted according to the ratio of the opening degrees of both guide vanes to achieve maximum energy efficiency. After reaching the minimum guide vane opening, the optimal opening degree of both guide vanes is calculated based on the minimum guide vane opening, and hot air bypass is introduced simultaneously to achieve maximum energy efficiency over a wide operating range, realizing high energy efficiency under all operating conditions.

[0150] Therefore, by calculating the optimal guide vane adjustment opening, the energy efficiency after the guide vane intervention is improved, so as to determine the optimal energy efficiency during the capacity adjustment process; at the same time, considering surge, the minimum guide vane opening is calculated. When it is less than the minimum guide vane opening, combined with hot gas bypass adjustment, a wide operating range can be achieved while taking into account high energy efficiency under all operating conditions.

[0151] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0152] Based on the same inventive concept, this application also provides a refrigeration unit control device for implementing the refrigeration unit control method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more embodiments of the refrigeration unit control device provided below can be found in the limitations of the refrigeration unit control method described above, and will not be repeated here.

[0153] In one exemplary embodiment, a refrigeration unit control device is provided. The refrigeration unit includes an evaporator, a compressor, a condenser, and a flash evaporator arranged sequentially. The flash evaporator 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 is provided near the evaporator and a right guide vane is provided near the condenser. Figure 9 As shown, the refrigeration unit control device includes: a pressure acquisition module 902, a power determination module 904, an opening degree determination module 906, and an opening degree adjustment module 908, wherein:

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

[0155] The power determination module 904 is used to determine the first power corresponding to the left guide vane and the second power corresponding to the right guide vane based on the evaporation pressure, condensation pressure, the opening degree of the left guide vane and the opening degree of the right guide vane.

[0156] The opening determination module 906 is used to determine the target guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized.

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

[0158] In one embodiment, the power determination module is further configured to determine the pressure ratio percentage based on the evaporation pressure, condensation pressure, and rated pressure ratio; determine the volumetric flow rate percentage based on the evaporation pressure and rated specific volume; determine the first power corresponding to the left guide vane based on the rated cooling capacity, pressure ratio percentage, volumetric flow rate percentage, and the opening degree of the left guide vane; and determine the second power corresponding to the right guide vane based on the rated cooling capacity, pressure ratio percentage, volumetric flow rate percentage, and the opening degree 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 based on the actual specific volume and the rated specific volume; and determine the volumetric flow rate percentage based on the specific volume percentage and the opening of the left guide vane.

[0160] In one embodiment, the opening determination module is further configured to determine the optimal guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized; determine the minimum guide vane opening based on the evaporation pressure and the condensation pressure; and 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 further configured 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; and to update the optimal guide vane opening based on the minimum guide vane opening and the specific volume percentage when the optimal guide vane opening is less than the minimum guide vane opening, and to 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 further includes a hot gas bypass module. The hot gas bypass module 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 determines that the optimal guide vane opening is less than the minimum guide vane opening. After determining the updated optimal guide vane opening as the target guide vane opening, the opening adjustment module controls the hot gas bypass to start before controlling the left and right guide vanes to work according to the target guide vane opening.

[0163] In one embodiment, the refrigeration unit control device further includes an air replenishment module, which is used to control the flash generator to replenish air to the left and right guide vanes according to the proportional control corresponding to the target guide vane opening.

[0164] In one embodiment, the refrigeration unit control device further includes a frequency modulation module, which is used to adjust the operating frequency of the compressor if it is determined that capacity adjustment is required before the pressure acquisition module acquires the evaporation pressure of the evaporator and the condensation pressure of the condenser; if the capacity requirement is still not met after the operating frequency is adjusted to the minimum value, the pressure acquisition module acquires the evaporation pressure of the evaporator and the condensation pressure of the condenser.

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

[0166] Each module in the aforementioned refrigeration unit control device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the 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 flash evaporator arranged sequentially. The flash evaporator 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 is provided near the evaporator and a right guide vane is provided near the condenser. The refrigeration unit control device includes a first pressure sensor, a second pressure sensor, and a controller. The first pressure sensor is disposed on the evaporator, and the second pressure sensor is disposed on the condenser. Both the first and second pressure sensors are 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 a first pressure sensor located on the evaporator and then sent to the controller. This first pressure sensor can continuously monitor the evaporation pressure to obtain more comprehensive data. The controller can continuously acquire the evaporation pressure from the first pressure sensor, acquire it at preset time intervals, or acquire it only when needed. Furthermore, the first pressure sensor can also detect the evaporation pressure only after receiving a start command from the controller and then send the data to the controller, enabling on-demand monitoring and reducing workload.

[0169] The condensing pressure of the condenser can be detected by a second pressure sensor located on the condenser, which is then sent to the controller. This second pressure sensor continuously monitors the condensing pressure to obtain more comprehensive data. The controller can continuously acquire the condensing pressure from the first pressure sensor, or acquire it at preset time intervals, or acquire it only when needed. Furthermore, the first pressure sensor can also detect the condensing pressure after receiving a start command from the controller and then send the data to the controller, enabling on-demand monitoring and reducing workload.

[0170] In this embodiment, based on the actual operating conditions of the refrigeration unit, the controller calculates the target guide vane adjustment opening to improve the energy efficiency after the guide vane is intervened, thereby improving the reliability of the energy regulation method of the refrigeration unit and thus improving 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 includes an evaporator, a compressor, a condenser, and a flash evaporator arranged sequentially. The flash evaporator is also connected to the evaporator and the compressor. The compressor is a double-cantilever, four-impeller, two-stage, parallel compression structure, with a left guide vane near the evaporator and a right guide vane near the condenser. When the refrigeration unit is operating, a portion of the low-temperature, low-pressure refrigerant gas exiting the evaporator enters the left side of the compressor, passes through the left guide vane, and enters the compressor interior. Another portion enters the right side of the compressor, passes through the right guide vane, and enters the compressor interior. Alternatively, it may only enter the left side of the compressor. The low-temperature, low-pressure refrigerant gas is then compressed by the compressor into a high-temperature, high-pressure refrigerant gas, which then enters the condenser. In the condenser, the refrigerant condenses from a high-temperature, high-pressure gas into a high-temperature, high-pressure liquid. It then enters the flash evaporator, where the generated gas is separated. The gas enters the gas inlet between the first and second stage impellers on both sides of the compressor, where the enthalpy is increased. The remaining saturated refrigerant liquid is throttled into a low-temperature, low-pressure refrigerant liquid, which then enters the evaporator to complete evaporation and heat absorption. The compressor is a two-stage parallel compression structure with double cantilever and four impellers. Guide vanes are installed in front of the impeller inlets on both sides, including left and right guide vanes.

[0172] In addition, the refrigeration unit may also include other structures. For example, such as... Figure 1 As shown, the refrigeration unit also includes a first electronic expansion valve and a second electronic expansion valve. The first electronic expansion valve is located in the channel between the flash evaporator and the evaporator, and the second electronic expansion valve is located in the channel between the condenser and the flash evaporator. Both the first and second electronic expansion valves function as throttling valves. Specifically, in the condenser, the refrigerant condenses from a high-temperature, high-pressure gas into a high-temperature, high-pressure liquid. After being throttled by the first electronic expansion valve, it enters the flash evaporator. In the flash evaporator, the gas generated during the first-stage throttling process is separated and enters the gas injection port between the first and second stage impellers on both sides of the compressor, where the injected gas increases enthalpy. The remaining saturated refrigerant liquid undergoes secondary throttling by the second electronic expansion valve into a low-temperature, low-pressure refrigerant liquid, which then enters the evaporator to complete evaporation and heat absorption.

[0173] Furthermore, in one embodiment, such as Figure 1As shown, 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 located in the channel between the evaporator and the left guide vane; the second solenoid valve is located in the channel between the evaporator and the right guide vane; the third solenoid valve is located in the channel between the flash evaporator and the left guide vane; and the fourth solenoid valve is located in the channel between the flash evaporator and the right guide vane. Specifically, the low-temperature, low-pressure refrigerant gas exiting the evaporator, depending on the current capacity, enters the left side of the compressor via the first solenoid valve and the right side of the compressor via the second solenoid valve. After the gas generated during the first-stage throttling process is separated in the flash evaporator, the gas enters the gas injection port between the first and second stage impellers on both sides of the compressor via the third and fourth solenoid valves, where the gas injection increases enthalpy. In this embodiment, the first, second, third, and fourth solenoid valves control the opening and closing of the passages, and the flow rate in the passage where the solenoid valve is located can also be adjusted by adjusting the opening degree of the solenoid valve.

[0174] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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 embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A refrigeration unit control method, characterized in that, The refrigeration unit includes an evaporator, a compressor, a condenser, and a flash evaporator arranged sequentially. The flash evaporator 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 is provided near the evaporator and a right guide vane is provided near the condenser. The method includes: Obtain the evaporation pressure of the evaporator and the condensation pressure of the condenser; Based on the evaporation pressure, the condensation pressure, the opening degree of the left guide vane and the opening degree of the right guide vane, the first power corresponding to the left guide vane and the second power corresponding to the right guide vane are determined. The target guide vane opening is determined based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized. The operation of the left and right guide vanes is controlled according to the target guide vane opening.

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

3. The method according to claim 2, characterized in that, The determination of the volumetric flow rate percentage based on the evaporation pressure and rated specific volume includes: The actual specific volume is determined based on the evaporation pressure. Determine the specific capacity percentage based on the actual specific capacity and the rated specific capacity; The volumetric flow rate percentage is determined based on the specific volume percentage and the opening of the left guide vane.

4. The method according to claim 1, characterized in that, The step of determining the target guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized includes: The optimal guide vane opening is determined based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized. The minimum guide vane opening is determined based on the evaporation pressure and the condensation pressure. The target guide vane opening is determined based on 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 based on the optimal guide vane opening and the minimum guide vane opening includes: If 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 specific volume percentage is obtained based on the evaporation pressure.

6. The method according to claim 5, characterized in that, 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. Before controlling the operation of the left and right guide vanes according to the target guide vane opening, the method further includes: Control the opening of the hot gas bypass.

7. The method according to claim 1, characterized in that, The method further includes: The flash generator is controlled to replenish air to the left and right guide vanes 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: If it is determined that capacity adjustment is required, adjust the operating frequency of the compressor; If 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 includes: Obtain the chilled water outlet temperature of the evaporator; If the chilled water outlet temperature is higher 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 includes an evaporator, a compressor, a condenser, and a flash evaporator arranged sequentially. The flash evaporator is also connected to the evaporator and the compressor. The compressor is a double-cantilever, four-impeller, two-stage compression parallel structure, with a left guide vane near the evaporator and a right guide vane near the condenser. The device includes: A pressure acquisition module is used to acquire the evaporation pressure of the evaporator and the condensation pressure of the condenser; The power determination module is used to determine the first power corresponding to the left guide vane and the second power corresponding to the right guide vane based on the evaporation pressure, the condensation pressure, the opening degree of the left guide vane and the opening degree of the right guide vane; An opening determination module is used to determine a target guide vane opening based on the opening of the left guide vane and the opening of the right guide vane when the sum of the first power and the second power is minimized. 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 includes an evaporator, a compressor, a condenser, and a flash evaporator arranged in sequence. The flash evaporator 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 is provided near the evaporator and a right guide vane is provided near the condenser. The refrigeration unit control equipment includes a first pressure sensor, a second pressure sensor, and a controller. The first pressure sensor is located on the evaporator, the second pressure sensor is located on the condenser, and both the first pressure sensor and the second pressure sensor are 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 any one of claims 1-9.

12. A refrigeration system, characterized in that, It includes a refrigeration unit and the refrigeration unit control equipment as described in claim 11.

13. The refrigeration system according to claim 12, characterized in that, The refrigeration unit also includes a first electronic expansion valve and a second electronic expansion valve. The first electronic expansion valve is disposed in the channel between the flash evaporator and the evaporator, and the second electronic expansion valve is disposed in the channel between the condenser and the flash evaporator.

14. The refrigeration system according to claim 13, characterized in that, 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 disposed in the channel between the evaporator and the left guide vane, the second solenoid valve is disposed in the channel between the evaporator and the right guide vane, the third solenoid valve is disposed in the channel between the flash evaporator and the left guide vane, and the fourth solenoid valve is disposed in the channel between the flash evaporator and the right guide vane.

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