A control method and control system of a multi-connected injector refrigeration system

Abstract

The application discloses a kind of multi-union ejector refrigeration system control method and control system, belong to refrigeration equipment control technical field.It includes: the refrigerant mass flow rate of detection gas cooler outlet;Determine the working number of ejector by the opening state of each ejector corresponding solenoid valve, and calculate the total area of nozzle throat of ejector in operation;According to the mass flow rate obtained by detection and the total area of nozzle throat of the ejector, calculate unit area mass flow rate;According to the size relationship between the unit area mass flow rate and the corresponding preset mass flow rate, determine the solenoid valve control method corresponding to each ejector;According to the solenoid valve control method, control the opening state of solenoid valve corresponding to each ejector.The application detects real-time flow, cooperates the control of corresponding solenoid valve, so that ejector always works in the best mode, to improve the purpose of system energy efficiency.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration equipment control technology, specifically relating to a control method and control system for a multi-ejector refrigeration system. Background Technology

[0002] Commercial CO2 refrigeration systems have entered a period of rapid development in recent years. Multi-ejector systems, with their excellent expansion work recovery and wide operating condition adaptability, have become one of the most effective devices for improving the performance of commercial CO2 refrigeration systems. Commercially available multi-ejector assemblies rely on a module that can accommodate 4–6 gas ejectors and 1–2 liquid ejectors. This combination allows for maximizing energy efficiency, and by switching or combining ejectors of different sizes, the refrigeration system can operate under a wider range of conditions.

[0003] Regarding ejector control methods, relevant patents such as "Method for Controlling a Variable Capacity Ejector Unit (Application No. 201580042402.0)" propose generating specific control signals for the ejector unit based on the temperature and pressure of the refrigerant at the ejector inlet to indicate whether to increase, decrease, or maintain the ejector unit's capacity. However, since the pressure of the refrigeration system is easily affected by other conditions and fluctuates frequently during actual operation, it inevitably leads to problems such as misadjustment and overshoot of the ejector unit. On the other hand, while relying on operators to manually adjust the ejector unit capacity according to the system's operating status has the advantage of simplicity and directness, this control method is both time-consuming and labor-intensive, and cannot be done quickly and promptly. It can easily lead to prolonged operation time of the system in non-optimal operating modes, reducing system energy efficiency.

[0004] Therefore, there is an urgent need in this field for a control method for multi-ejector refrigeration systems that can achieve safe operation, timely response, automatic control, and reduced operating costs. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a control method and control system for a multi-ejector refrigeration system, so as to solve the technical problems of misalignment and poor system energy efficiency caused by manual control in the prior art.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a control method for a multi-ejector refrigeration system, comprising the following steps:

[0008] Detect the refrigerant mass flow rate m at the outlet of the gas cooler;

[0009] The number of operating injectors is determined by the opening status of the solenoid valves corresponding to each injector in the system, and then the total nozzle throat area A of the operating injectors is calculated. t ;

[0010] Calculate the mass flow rate per unit area, i.e., m / A, based on the refrigerant mass flow rate and the total area of ​​the nozzle throat of the operating ejector. t ;

[0011] Based on the relationship between the mass flow rate per unit area and the corresponding preset mass flow rate, the control strategy for the solenoid valves of each injector is determined, and the opening state of the solenoid valves is controlled.

[0012] Correspondence refers to the relationship between the measured mass flow rate per unit area and the input preset mass flow rate. The mass flow rate per unit area is obtained by detecting the real-time flow of the system. This value is the actual operating value of the system and represents the real-time operating parameter of the system. The corresponding preset mass flow rate is the value input before the system is started and represents the set system operating parameter. By comparing the magnitudes of these two values, the deviation between the system's operating state and the set state can be clearly understood, and adjustments can then be made based on this.

[0013] Preferably, the refrigerant mass flow rate at the outlet of the gas cooler is detected by a sensor.

[0014] Preferably, if the calculated mass flow rate per unit area is greater than the preset upper limit of the mass flow rate, the corresponding solenoid valve is switched to open to increase the flow area of ​​the injector.

[0015] Preferably, if the calculated mass flow rate per unit area is less than the preset lower limit of the mass flow rate, the corresponding solenoid valve is switched to open to reduce the flow area of ​​the injector.

[0016] Preferably, if the calculated mass flow rate per unit area is less than the preset upper limit of the mass flow rate but greater than the preset lower limit of the mass flow rate, then the existing solenoid valve is kept open.

[0017] This invention also discloses a control system based on the above-described control method for a multi-ejector refrigeration system, comprising:

[0018] The refrigerant mass flow rate detection module is used to detect the refrigerant mass flow rate m at the outlet of the gas cooler.

[0019] The nozzle throat total area calculation module is used to determine the number of operating injectors by the opening status of the solenoid valves corresponding to each injector in the system, and to calculate the total nozzle throat area A of the operating injectors. t ;

[0020] The unit area mass flow rate calculation module is used to calculate the unit area mass flow rate, i.e., m / A, based on the refrigerant mass flow rate and the total area of ​​the nozzle throat of the operating ejector. t ;

[0021] The solenoid valve operation control module is used to determine the solenoid valve control strategy for each injector based on the relationship between the unit area mass flow rate and the corresponding preset mass flow rate, and to control the opening state of the solenoid valve.

[0022] Preferably, in the refrigerant mass flow detection module, the refrigerant mass flow rate at the outlet of the gas cooler is detected by a sensor.

[0023] Preferably, in the solenoid valve operation control module, determining the solenoid valve control strategy corresponding to each injector includes:

[0024] If the calculated mass flow rate per unit area is greater than the preset upper limit of the mass flow rate, the corresponding solenoid valve is switched to open to increase the flow area of ​​the injector.

[0025] If the calculated mass flow rate per unit area is less than the preset lower limit of the mass flow rate, the corresponding solenoid valve is switched to open to reduce the flow area of ​​the injector.

[0026] If the calculated mass flow rate per unit area is less than the preset upper limit of the mass flow rate but greater than the preset lower limit of the mass flow rate, then the existing solenoid valve will remain open.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention discloses a control method for a multi-ejector refrigeration system. By acquiring the refrigerant flow rate at the gas cooler outlet and the number of operating ejectors, the method obtains the mass flow rate per unit area at the throat. Based on the relationship between the detected mass flow rate and a preset value, it controls the opening or closing of relevant solenoid valves. In other words, by controlling the mass flow rate per unit area within the ejectors in the refrigeration system, the ejectors are kept in optimal operating mode, thereby improving system energy efficiency. Because the refrigerant mass flow rate is less affected by other conditions and exhibits high stability, the risk of system misadjustment is avoided. Furthermore, this invention does not incur additional power consumption or hardware costs, and the control principle is simple and easy to operate, effectively improving the system performance of the multi-ejector refrigeration system under different loads. Attached Figure Description

[0029] Figure 1 This is a flowchart of the control method for the multi-ejector refrigeration system disclosed in this invention;

[0030] Figure 2This is a schematic diagram of the system structure of a multi-ejector refrigeration system based on the control method of the present invention, provided in an embodiment of the present invention.

[0031] Wherein: 1-High temperature compressor unit; 2-Gas cooler; 3-Multi-ejector, 301, 302, 303, 304, and 305 are all ejectors; 4-Gas-liquid separator; 5-Medium temperature expansion valve; 6-Low temperature expansion valve; 7-Low temperature evaporator; 8-Flooded evaporator; 9-Low temperature compressor; 10-Liquid receiver; 11-Mass flow sensor; 12-Solenoid valve group, 1201, 1202, 1203, 1204, and 1205 are all solenoid valves. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0033] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0034] The present invention will now be described in further detail with reference to the accompanying drawings:

[0035] See Figure 1 The control method for the multi-ejector refrigeration system of the present invention includes:

[0036] The refrigerant mass flow rate m at the outlet of the gas cooler is detected by a sensor.

[0037] The number of injectors in operation is determined by the opening status of the solenoid valves corresponding to each injector, and the total nozzle throat area A of the injectors in operation is calculated. t ;

[0038] The mass flow rate per unit area (m / A) is calculated based on the detected mass flow rate and the total area of ​​the nozzle throat of the injector. t ;

[0039] Based on the relationship between the mass flow rate per unit area and the corresponding preset mass flow rate, the control method of the solenoid valve for each injector is determined.

[0040] The opening state of the solenoid valve corresponding to each injector is controlled according to the solenoid valve control method described above.

[0041] Optionally, the method for determining the solenoid valve control method for each injector based on the relationship between the unit area mass flow rate and the corresponding preset mass flow rate includes:

[0042] If the current mass flow rate per unit area is greater than the upper limit of the preset mass flow rate, then switch the corresponding solenoid valve to open to increase the flow area of ​​the injector.

[0043] If the current mass flow rate per unit area is less than the lower limit of the preset mass flow rate, the corresponding solenoid valve is switched to open to reduce the flow area of ​​the injector.

[0044] If the current mass flow rate per unit area is less than the upper limit of the preset mass flow rate but greater than the lower limit of the preset mass flow rate, then the existing solenoid valve open state is maintained.

[0045] See Figure 2 ,by Figure 2The control method of the present invention is described using a multi-ejector refrigeration system with the structure shown as an example. This multi-ejector refrigeration system includes: a high-temperature compressor unit 1, a gas cooler 2, a multi-ejector system 3, a gas-liquid separator 4, a medium-temperature expansion valve 5, a low-temperature expansion valve 6, a low-temperature evaporator 7, a flooded evaporator 8, a low-temperature compressor 9, and a liquid receiver 10. The high-pressure outlet of the high-temperature compressor unit 1 is connected to the inlet of the gas cooler 2. The high-temperature compressor unit 1 consists of three identical compressors connected in parallel. The outlet of the gas cooler 2 is connected to the main flow inlet of the multi-ejector system 3. The outlet pipeline of the gas cooler 2 is equipped with... A mass flow sensor 11 is installed. The multi-jet injector 3 consists of five injectors 301 to 305 with a throat area ratio of 1:2:4:8:1. Injectors 301 to 304 are gas injectors, and injector 305 is a liquid injector. A solenoid valve group 12 is installed at the inlet end of the multi-jet injector 3. The solenoid valve group 12 contains five solenoid valves 1201 to 1205, which respectively control injectors 301 to 305. The outlet of the multi-jet injector 3 is connected to the inlet of the gas-liquid separator 4. The gas outlet end of the gas-liquid separator 4 is connected to the inlet of the high-temperature compressor unit 1 to form a high-pressure circulation loop. The liquid outlet of the gas-liquid separator 4 is divided into two parts: one part is connected to the inlet of the medium-temperature expansion valve 5, and the other part is connected to the inlet of the low-temperature expansion valve 6. The outlet of the medium-temperature expansion valve 5 is connected to the inlet of the flooded evaporator 8, and the outlet of the low-temperature expansion valve 6 is connected to the inlet of the low-temperature evaporator 7. The outlet of the low-temperature evaporator 7 is connected to the low-pressure inlet of the low-temperature compressor 9. The high-pressure outlet of the low-temperature compressor 9 merges with the outlet of the flooded evaporator 8 and is connected to the inlet of the liquid receiver 10. The gas outlet of the liquid receiver 10 is divided into four parts and is connected to the jet inlets of the gas ejectors 301 to 304 of the multi-ejector 3. The liquid outlet of the liquid receiver 10 is connected to the jet inlet of the liquid ejector 305, forming a low-pressure circulation loop.

[0046] This multi-ejector refrigeration system, when in operation:

[0047] The refrigerant becomes a high-temperature, high-pressure gas under the action of the high-temperature compressor unit 1. After being cooled in the gas cooler 2, this high-temperature, high-pressure gas enters the main flow nozzle of the multi-ejector 3 through the solenoid valve. The gas ejector 301-304 and the liquid ejector 305 respectively eject the saturated gas and saturated liquid from the liquid receiver 10. The mixed fluid at the outlet of the multi-ejector 3 enters the gas-liquid separator 4. The separated saturated gas enters the high-temperature compressor unit 1 through the gas outlet and is recompressed to complete the high-pressure side cycle. Part of the separated saturated liquid enters the flooded evaporator 8 through the medium-temperature expansion valve 5, and the other part enters the low-temperature evaporator 7 through the low-temperature expansion valve 6 to provide dual-temperature refrigeration. The refrigerant at the outlet of the low-temperature evaporator 7 is compressed by the low-temperature compressor 9 and enters the low-pressure liquid receiver 10 together with the two-phase refrigerant at the outlet of the flooded evaporator 8. Then it is separated into saturated gas and saturated liquid as ejector streams and enters the multi-ejector 3 to complete the low-pressure side cycle. During this process, the refrigerant flow rate entering the multi-injector 3 is monitored and collected in real time by the mass flow sensor 11 installed at the outlet of the gas cooler 2, and the operating status of the injector is controlled by the solenoid valves 1201 to 1205 installed at the inlet of each injector.

[0048] Specifically, in the multi-ejector refrigeration system described in this embodiment, the high-temperature compressor unit 1 consists of 3 units with a theoretical discharge capacity of 12m³ / h. 3 The system consists of parallel compressors with a rated speed of 1450 r / min. Gas cooler 2 and low-temperature evaporator 7 are plate heat exchangers with designed heat exchange capacities of 220 kW and 55 kW respectively. Flooded evaporator 8 is a shell-and-tube heat exchanger with a designed heat exchange capacity of 90 kW. The smallest ejector in the multi-ejector unit 3, 301, has a nozzle throat cross-sectional area of ​​1.63 × 10⁻⁶. -6 m 2 By switching or combining them, the multi-ejector unit 3 can provide 15 different ejector operating areas to adapt to system requirements. The gas-liquid separator 4 and the liquid receiver 10 are designed to operate at pressures of 12 MPa and 5.5 MPa, respectively. For the refrigeration system described in this embodiment, by changing the number and frequency of the high-temperature compressor unit 1, the refrigeration output requirement of 75–115 kW can be easily met.

[0049] Specifically, regarding such as Figure 2 The multi-ejector refrigeration system shown below has the following control method:

[0050] Step S10: Detect the refrigerant mass flow rate m at the outlet of the gas cooler using a sensor;

[0051] Specifically, the control system detects and collects the refrigerant flow rate entering the multi-ejector 3 through a mass flow sensor 11 installed at the outlet of the gas cooler 2.

[0052] Step S20: Determine the number of injectors in operation by checking the opening status of the solenoid valves corresponding to each injector, and calculate the total nozzle throat area A of the injectors in operation. t ;

[0053] Specifically, the number of operating injectors is determined by the opening state of solenoid valves 1201-1205 installed at the inlet of each injector. The opening states of solenoid valves 1201-1205 are denoted as x1-x5, where 1 represents an open solenoid valve and 0 represents a closed solenoid valve. A1-A5 represent the throat cross-sectional areas of injectors 301-305. Therefore, the total nozzle throat area A of the operating injectors can be calculated based on the states of solenoid valves 1201-1205. t =x1A1+x2A2+x3A3+x4A4+x5A5.

[0054] Step S30: Calculate the unit area mass flow rate (m / A) based on the detected mass flow rate and the total area of ​​the nozzle throat of the injector. t ;

[0055] Step S40: Determine the solenoid valve control method for each injector based on the relationship between the unit area mass flow rate and the input preset mass flow rate.

[0056] Specifically, by calculating the mass flow rate per unit area at the ejector throat and comparing it to the preset mass flow rate, it's possible to determine whether the ejector's operating mode is reasonable—that is, whether the ejector throat operating area is too large, too small, or appropriate. Further control methods are then determined based on the ejector's operating status to address the issue of an excessively large or small throat operating area. Simultaneously, the preset value is the mass flow rate per unit area that maintains the system's highest efficiency under all operating conditions, determined through extensive simulations and experiments before the system is put into use. This allows for real-time monitoring of the mass flow rate during system operation to determine whether the system is operating at its highest efficiency, and adjustments to the ejector can be made to change the mass flow rate. For the refrigeration system described in this embodiment, the mass flow rate per unit area at the ejector throat is consistently maintained at 40.5–43.0 g / (s·mm²). 2 When the temperature is between 40.5 and 43.0 g / (s·mm), the system exhibits the highest operating efficiency to cope with different cooling capacities; therefore, the preset value is 40.5–43.0 g / (s·mm). 2 The optimal mass flow rate is used as the criterion for the ejector operating mode.

[0057] Step S50: Control the opening state of the solenoid valve corresponding to each injector according to the solenoid valve control method.

[0058] Specifically, the current operating state of the ejector is determined based on the current mass flow rate per unit area of ​​the ejector throat, and the solenoid valve is opened or closed accordingly. This controls the operating area of ​​the ejector in the refrigeration system, ensuring that the ejector is in the optimal working mode and thus improving the energy efficiency of the refrigeration system.

[0059] Multi-ejector refrigeration systems are currently the latest CO2 refrigeration systems applied in multi-temperature zones such as supermarkets and cold storage facilities. These systems can adapt to or actively adjust system performance by switching or combining different ejectors. Currently, adjustment of multi-ejector systems relies heavily on manual operation, requiring 24-hour on-call management. This makes it difficult to guarantee timely response and rapid adjustment when system operating conditions change, extending the system's operating time in suboptimal modes and leading to reduced energy efficiency. In contrast, while automatic adjustment based on ejector inlet pressure and temperature offers timely and rapid control, frequent pressure fluctuations due to other factors increase the risk of misadjustment and overshoot, jeopardizing stable system operation.

[0060] This invention discloses a control method for a multi-ejector refrigeration system. By using sensors to monitor and collect flow information in real time, and by accurately reading the operating status of the ejectors through the opening and closing of solenoid valves, the system can flexibly and accurately obtain the system operating mode. Based on the calculated relationship between the mass flow rate per unit area of ​​the ejector throat and the preset optimal mass flow rate, the method can promptly determine whether the working area of ​​the ejector is too large, too small, or appropriate. In this way, the method controls the opening or closing of the corresponding solenoid valve of the ejector to adjust the ejector operating mode and control the refrigeration system to work in the optimal operating mode.

[0061] When the obtained mass flow rate per unit area of ​​the throat is too high, that is, the working area of ​​the ejector throat is too small, this will lead to an increase in system pressure, increase the power consumption of the refrigeration compressor, and at the same time, due to the limitation of the ejector flow area, the system cannot operate at maximum flow, weakening the system's cooling capacity. It is necessary to adjust the opening state of the solenoid valve in time to control the ejector to switch operating modes and increase the ejector operating area. Conversely, when the obtained mass flow rate per unit area of ​​the throat is too low, it will lead to an excessively low system pressure, weaken the ejector's entrainment ability, and reduce the expansion work recovery efficiency. It is necessary to reduce the ejector operating area.

[0062] In this embodiment, the control method for the multi-ejector refrigeration system only controls ejectors 301-304 via solenoid valves 1201-1204, while solenoid valve 1205 is controlled by the liquid level in the reservoir 10. To avoid overshoot, when the ejector operating area needs to be increased or decreased, the adjustment is determined in units of the throat area of ​​ejector 301, and the solenoid valve control scheme is maintained through real-time monitoring and rapid response to ensure precise control of the multi-ejector refrigeration system. For the refrigeration system described in this embodiment, within a cooling load range of 75-115kW, compared to a constant ejector operating area, the control method avoids the system operating in suboptimal mode, resulting in an average COP increase of 2.89%, especially at low loads, where the COP increases by up to 9.58%.

[0063] This invention provides a control method for a multi-ejector refrigeration system. In existing multi-ejector refrigeration systems, by detecting real-time flow through sensors and coordinating with the control of corresponding solenoid valves, this invention offers more flexible and accurate judgment of system operating status and control of the opening and closing of each solenoid valve compared to existing manual control and pressure-based control technologies. It solves the problems of slow response and poor precision in manual operation, avoids misadjustment caused by normal system fluctuations, and prevents prolonged operation in suboptimal modes due to untimely operation, enabling the system to achieve automatic, accurate, and rapid control.

[0064] Further, step S40, based on the relationship between the unit area mass flow rate and the corresponding preset mass flow rate, determines the solenoid valve control method for each injector, including:

[0065] Step S41: If the current mass flow rate per unit area is greater than the upper limit of the preset mass flow rate, then switch the opening state of the corresponding solenoid valve to increase the flow area of ​​the injector.

[0066] Step S42: If the current mass flow rate per unit area is less than the lower limit of the preset mass flow rate, then switch the opening state of the corresponding solenoid valve to reduce the flow area of ​​the injector.

[0067] Step S43: If the current mass flow rate per unit area is less than the upper limit of the preset mass flow rate and greater than the lower limit of the preset mass flow rate, then maintain the existing solenoid valve open state.

[0068] Specifically, when the refrigeration system adjusts the ejector's operating mode, it determines the specific adjustment scheme based on the relationship between the currently measured mass flow rate per unit area at the throat and the preset optimal mass flow rate. If the current mass flow rate per unit area is greater than the upper limit of the preset mass flow rate, it indicates that the operating area of ​​the ejector needs to be increased; if the current mass flow rate per unit area is less than the lower limit of the preset mass flow rate, it indicates that the operating area of ​​the ejector needs to be decreased; if the current mass flow rate per unit area is within the preset mass flow rate range, it indicates that the system is operating in the optimal mode and no additional adjustment is required.

[0069] Further, step S41, which states that if the current mass flow rate per unit area is greater than the upper limit of the preset mass flow rate, switches the corresponding solenoid valve to open to increase the flow area of ​​the injector, includes:

[0070] Step S411: If the solenoid valve 1201 is currently in the closed state, then open the solenoid valve 1201.

[0071] Step S412: If solenoid valve 1201 is currently in the open state and solenoid valve 1202 is currently in the closed state, then solenoid valve 1202 is opened and solenoid valve 1201 is closed.

[0072] Step S413: If solenoid valves 1201 and 1202 are currently in the open state and solenoid valve 1203 is currently in the closed state, then solenoid valve 1203 is opened and solenoid valves 1201 and 1202 are closed.

[0073] Step S414: If solenoid valves 1201, 1202, and 1203 are currently in the open state and solenoid valve 1204 is currently in the closed state, then solenoid valve 1204 is opened and solenoid valves 1201, 1202, and 1203 are closed.

[0074] Step S415: If solenoid valves 1201, 1202, 1203, and 1204 are currently in the open state, then maintain the existing open state of the solenoid valves.

[0075] Specifically, the refrigeration system increases the operating area of ​​the ejector by switching the ejector by controlling the opening state of the corresponding solenoid valve. In order to avoid overshoot, the refrigeration system needs to determine the opening state of all current solenoid valves when opening a new solenoid valve in order to determine the specific solenoid valve control scheme.

[0076] Further, step S42, which states that if the current mass flow rate per unit area is less than a preset lower limit of the mass flow rate, then switching the opening state of the corresponding solenoid valve to reduce the flow area of ​​the injector, includes:

[0077] Step S421: If the solenoid valve 1201 is currently in the open state, then close the solenoid valve 1201.

[0078] Step S422: If solenoid valve 1201 is currently in the closed state and solenoid valve 1202 is currently in the open state, then close solenoid valve 1202 and open solenoid valve 1201.

[0079] Step S423: If solenoid valves 1201 and 1202 are currently closed and solenoid valve 1203 is currently open, then close solenoid valve 1203 and open solenoid valves 1201 and 1202.

[0080] Step S424: If solenoid valves 1201, 1202, and 1203 are currently in the closed state and solenoid valve 1204 is currently in the open state, then close solenoid valve 1204 and open solenoid valves 1201, 1202, and 1203.

[0081] Specifically, the refrigeration system reduces the operating area of ​​the ejector by switching the ejector by controlling the opening state of the corresponding solenoid valve. In order to avoid overshoot, the refrigeration system needs to determine the opening state of all solenoid valves when closing a new solenoid valve in order to determine the specific solenoid valve control scheme.

[0082] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A control method for a multi-ejector refrigeration system, characterized in that, Includes the following steps: Detecting the refrigerant mass flow rate at the outlet of the gas cooler m ; The number of operating injectors is determined by the opening status of the solenoid valves corresponding to each injector in the system, and then the total nozzle throat area of ​​the operating injectors is calculated. A t ; Calculate the mass flow rate per unit area based on the refrigerant mass flow rate and the total area of ​​the nozzle throat of the operating ejector. m / A t ; Based on the relationship between the mass flow rate per unit area and the preset mass flow rate, determine the control strategy for the solenoid valves corresponding to each injector and control the opening state of the solenoid valves. The determination of the solenoid valve control strategy for each injector includes: If the calculated mass flow rate per unit area is greater than the preset upper limit of the mass flow rate, the corresponding solenoid valve is switched to open to increase the flow area of ​​the injector. If the calculated mass flow rate per unit area is less than the preset lower limit of the mass flow rate, the corresponding solenoid valve is switched to open to reduce the flow area of ​​the injector. If the calculated mass flow rate per unit area is less than the preset upper limit of the mass flow rate but greater than the preset lower limit of the mass flow rate, then the existing solenoid valve will remain open.

2. The control method for the multi-ejector refrigeration system according to claim 1, characterized in that, The refrigerant mass flow rate at the outlet of the gas cooler is detected by a sensor.

3. The control method for the multi-ejector refrigeration system according to claim 1, characterized in that, If the calculated mass flow rate per unit area is greater than the preset upper limit of the mass flow rate, the corresponding solenoid valve is switched to open to increase the flow area of ​​the injector.

4. The control method for the multi-ejector refrigeration system according to claim 1, characterized in that, If the calculated mass flow rate per unit area is less than the preset lower limit of the mass flow rate, the corresponding solenoid valve is switched to open to reduce the flow area of ​​the injector.

5. The control method for the multi-ejector refrigeration system according to claim 1, characterized in that, If the calculated mass flow rate per unit area is less than the preset upper limit of the mass flow rate but greater than the preset lower limit of the mass flow rate, then the existing solenoid valve will remain open.

6. A control system based on the control method of the multi-ejector refrigeration system according to any one of claims 1 to 5, characterized in that, include: The refrigerant mass flow detection module is used to detect the refrigerant mass flow rate at the outlet of the gas cooler. m ; The nozzle throat total area calculation module is used to determine the number of operating injectors by the opening status of the solenoid valves corresponding to each injector in the system, and to calculate the total nozzle throat area of ​​the operating injectors. A t ; The unit area mass flow rate calculation module is used to calculate the unit area mass flow rate based on the refrigerant mass flow rate and the total area of ​​the nozzle throat of the operating ejector. m / A t ; The solenoid valve operation control module is used to determine the solenoid valve control strategy for each injector based on the relationship between the unit area mass flow rate and the corresponding preset mass flow rate, and to control the opening state of the solenoid valve. In the solenoid valve operation control module, the solenoid valve control strategy for each injector includes: If the calculated mass flow rate per unit area is greater than the preset upper limit of the mass flow rate, the corresponding solenoid valve is switched to open to increase the flow area of ​​the injector. If the calculated mass flow rate per unit area is less than the preset lower limit of the mass flow rate, the corresponding solenoid valve is switched to open to reduce the flow area of ​​the injector. If the calculated mass flow rate per unit area is less than the preset upper limit of the mass flow rate but greater than the preset lower limit of the mass flow rate, then the existing solenoid valve will remain open.

7. The control system according to claim 6, characterized in that, In the refrigerant mass flow detection module, the refrigerant mass flow rate at the outlet of the gas cooler is detected by a sensor.

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