A control method of a multi-connected refrigeration system and a terminal device

Abstract

The application is suitable for the field of refrigeration technology, and provides a control method of a multi-connected refrigeration system and terminal equipment. The method comprises: when the refrigeration demand of a terminal system is less than a first preset value, keeping at least one multi-connected refrigeration module in a running state, and executing a shutdown logic for shutting down other multi-connected refrigeration modules; wherein the shutdown logic at least comprises: after refrigerant in a liquid accumulator of a multi-connected refrigeration module executing the shutdown logic is transported to liquid accumulators of other multi-connected refrigeration modules in a running state, closing a fluorine pump. The method can avoid the cavitation phenomenon of the multi-connected refrigeration module in the running state, improve the refrigeration effect, and improve the stability of the multi-connected refrigeration system.

Description

Technical Field

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

[0002] A multi-split refrigeration system (also known as a refrigerant pump system) is an air conditioning system that uses a refrigerant pump to drive the refrigerant. A multi-split refrigeration system generally includes a terminal system for data center rooms and a multi-split refrigeration module. The multi-split refrigeration module generally includes a primary side and a secondary side refrigeration system. When the refrigeration is turned on, the evaporated refrigerant returns to the heat exchanger of the multi-split refrigeration module to be condensed, and then is transported by the refrigerant pump to the evaporator of the terminal system, and the cycle repeats.

[0003] The primary-side refrigeration system is typically used during spring and summer when the compressor system of the multi-split refrigeration module operates normally. The low-temperature, low-pressure refrigerant from the primary side enters the liquid side of the plate heat exchanger, condensing the gaseous refrigerant from the secondary side into liquid refrigerant. In autumn and winter, when the outdoor temperature falls below the controller's preset temperature, the controller automatically switches to natural cooling fan coil unit refrigeration: the gaseous refrigerant from the secondary side enters the fan coil unit and is condensed into liquid refrigerant by natural cold. During cold outdoor seasons, the compressor of the primary-side system in the multi-split refrigeration system does not need to be turned on; only the refrigerant pump needs to be activated. Since the power of the refrigerant pump is much smaller than that of the refrigeration compressor, under the same cooling capacity, the refrigerant pump has a higher energy efficiency ratio than the refrigeration compressor, thus achieving energy savings while achieving cooling.

[0004] However, in existing multi-unit cooling system control methods, when the load on the data center terminal system decreases, the main control system typically shuts down multi-unit cooling modules randomly or selects which modules to shut down based on their operating time. This can lead to the shutdown of multi-unit cooling modules with high liquid refrigerant levels in their receivers, locking a large amount of liquid refrigerant in these closed modules. Consequently, the remaining modules still in the cooling cycle have less refrigerant. When the refrigerant pressure or subcooling of the refrigerant pump inlet is low, there may be a higher concentration of gaseous refrigerant at the pump inlet, resulting in cavitation. Cavitation leads to several problems. First, it reduces the pump head and refrigerant flow, causing refrigerant interruption and reducing system cooling capacity, resulting in poorer temperature control at the server end. Second, cavitation damages components such as the pump impeller, reducing system reliability and potentially causing pump failure. This ultimately leads to decreased stability of the entire system. Summary of the Invention

[0005] This application provides a control method and terminal device for a multi-unit refrigeration system, which can prevent cavitation of the multi-unit refrigeration module in operation while improving its cooling effect, thereby improving the stability of the multi-unit refrigeration system.

[0006] In a first aspect, embodiments of this application provide a control method for a multi-unit refrigeration system. The multi-unit refrigeration system includes a terminal system and at least two parallel multi-unit refrigeration modules. Each multi-unit refrigeration module includes at least a liquid receiver and a refrigerant pump. The control method includes:

[0007] When the cooling demand of the terminal system is less than the first preset value, at least one multi-unit cooling module is kept running, and shutdown logic is executed to shut down other multi-unit cooling modules.

[0008] The shutdown logic includes at least the following: after transferring the refrigerant in the receiver of the multi-unit refrigeration module that is executing the shutdown logic to the receiver of other multi-unit refrigeration modules that are in operation, the refrigerant pump is turned off.

[0009] In one possible implementation of the first aspect, after the refrigerant in the receiver of the multi-unit refrigeration module executing the shutdown logic is transferred to the receiver of other multi-unit refrigeration modules in operation, the refrigerant pump is turned off, specifically including:

[0010] The first refrigerant pump of the multi-unit refrigeration module that executes the shutdown logic is raised to the first preset frequency, while the second refrigerant pump of other multi-unit refrigeration modules that are in operation are operated at the average frequency, wherein the first preset frequency is greater than the average frequency.

[0011] When the pressure difference between the inlet and outlet of the first fluorine pump is less than or equal to the preset target pressure difference, the first fluorine pump is shut down after restoring the original frequency operation of the first and second fluorine pumps.

[0012] In one possible implementation of the first aspect, after the first refrigerant pump of the multi-unit refrigeration module executing the shutdown logic is increased to a first preset frequency and the second refrigerant pumps of other multi-unit refrigeration modules in operation are running at an average frequency, the method further includes:

[0013] When the pressure difference between the inlet and outlet of the first fluorine pump is greater than the preset target pressure difference, the first fluorine pump will be increased to the second preset frequency for operation, and the other second fluorine pumps will operate at the average frequency, wherein the second preset frequency is greater than the first preset frequency.

[0014] When the pressure difference between the inlet and outlet of the first fluorine pump is less than or equal to the preset target pressure difference, the first fluorine pump is shut down after restoring the original frequency operation of the first and second fluorine pumps.

[0015] In one possible implementation of the first aspect, the method includes: when the first fluorine pump is a gear pump, the first preset frequency is set to be 5-15 Hz higher than the average frequency; when the first fluorine pump is a centrifugal pump, the first preset frequency is set to be at least 20 Hz higher than the average frequency.

[0016] In one possible implementation of the first aspect, each multi-unit refrigeration module further includes at least a compressor, a mechanical cooling solenoid valve, a fan, and a natural cooling solenoid valve; the method includes:

[0017] The shutdown logic includes at least the following steps: first, shutting down the compressor and fan; then, transferring the refrigerant in its receiver to the receivers of other multi-unit refrigeration modules that are in operation; shutting down the refrigerant pump; and finally, shutting down the mechanical cooling solenoid valve and / or the natural cooling solenoid valve.

[0018] In one possible implementation of the first aspect, the method further includes:

[0019] After executing the shutdown logic to shut down other multi-unit cooling modules, and only one multi-unit cooling module is running, if the cooling demand of the terminal system is less than the second preset value, the running multi-unit cooling module will be switched to idle mode.

[0020] In one possible implementation of the first aspect, each multi-unit refrigeration module further includes at least a compressor, a mechanically cooled solenoid valve, a fan, a fan coil unit, a natural cooling solenoid valve, and a bypass solenoid valve;

[0021] The compressor is located in the primary refrigeration circuit of the multi-unit refrigeration module; the mechanical cooling solenoid valve, fan coil unit, natural cooling solenoid valve, bypass solenoid valve, liquid receiver and refrigerant pump are located in the secondary refrigeration circuit of the multi-unit refrigeration module. The fan is used to drive natural cooling air to exchange heat with the fan coil unit. The terminal system is connected in series with the secondary refrigeration circuit.

[0022] The mechanical refrigeration solenoid valve, the primary refrigeration circuit, the liquid receiver, the refrigerant pump, and the terminal system are connected in sequence to form a mechanical refrigeration cycle circuit;

[0023] The natural cooling solenoid valve, fan coil unit, liquid receiver, refrigerant pump and terminal system are connected in sequence to form a natural cooling circulation loop;

[0024] The natural cooling solenoid valve, fan coil unit, primary side refrigeration circuit, liquid receiver, refrigerant pump and terminal system are connected in sequence to form a mixed refrigeration cycle circuit;

[0025] The bypass solenoid valve is located between the mechanically cooled solenoid valve and the terminal system, and is used to bypass the primary side refrigeration circuit, the receiver and the refrigerant pump;

[0026] When the multi-unit refrigeration module is in idle mode, the compressor, fan, and natural cooling solenoid valve are all closed, while the mechanical cooling solenoid valve and bypass solenoid valve are open, and the refrigerant pump runs at the lowest frequency.

[0027] In one possible implementation of the first aspect, when the multi-unit cooling module is in idle mode, the method further includes:

[0028] When the cooling demand of the terminal system exceeds the third preset value, the outdoor ambient temperature of the multi-split refrigeration system is obtained;

[0029] The multi-unit refrigeration module switches from idle to refrigeration mode based on the outdoor ambient temperature.

[0030] In one possible implementation of the first aspect, the refrigeration state includes one of the following: natural refrigeration state, mechanical refrigeration state, and hybrid refrigeration state;

[0031] In the natural cooling mode, the compressor, mechanical cooling solenoid valve and bypass solenoid valve are closed, the natural cooling solenoid valve is open, and the fan and refrigerant pump operate at preset frequencies.

[0032] In the mechanical cooling mode, the fan, natural cooling solenoid valve and bypass solenoid valve are closed, the mechanical cooling solenoid valve is open, and the compressor and refrigerant pump operate at preset frequencies.

[0033] In the mixed cooling state, the mechanical cooling solenoid valve and bypass solenoid valve are closed, the natural cooling solenoid valve is open, and the compressor, fan and refrigerant pump operate at preset frequencies.

[0034] In a second aspect, embodiments of this application provide a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method as described in any of the first aspects.

[0035] This application provides a control method and terminal device for a multi-unit refrigeration system. When the cooling demand of the terminal system reaches the point where one or more multi-unit refrigeration modules need to be shut down, the refrigerant in the receiver of the multi-unit refrigeration module executing the shutdown logic is transferred to the receiver of other multi-unit refrigeration modules in operation before the refrigerant pump is turned off. This ensures that the receivers of the multi-unit refrigeration modules in operation have a relatively stable liquid refrigerant level and continuous liquid flow, avoiding the problem of "cavitation" and refrigerant interruption caused by the pressure drop in the receiver due to the outdoor ambient temperature or other influencing factors. This improves the cooling effect of the multi-unit refrigeration modules in operation and enhances the stability of the multi-unit refrigeration system. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of a multi-unit refrigeration system provided in one embodiment of this application;

[0038] Figure 2 This is a schematic flowchart of a control method for a multi-unit refrigeration system provided in an embodiment of this application;

[0039] Figure 3 This is a schematic diagram of the overall flow of a control method for a multi-unit refrigeration system provided in an embodiment of this application;

[0040] Figure 4 This is a flowchart illustrating an idle mode logic provided in an embodiment of this application;

[0041] Figure 5 This is a schematic flowchart of a cooling logic provided in an embodiment of this application;

[0042] Figure 6 This is a flowchart illustrating a control method for a multi-unit refrigeration system according to another embodiment of this application;

[0043] Figure 7 This is a flowchart illustrating a shutdown logic provided in an embodiment of this application;

[0044] Figure 8 This is a schematic diagram of the structure of a terminal device provided in an embodiment of this application. Detailed Implementation

[0045] The control method for the multi-unit cooling system provided in this application embodiment can be applied to terminal devices such as mobile phones, tablets, in-vehicle devices, augmented reality (AR) / virtual reality (VR) devices, laptops, ultra-mobile personal computers (UMPCs), netbooks, and personal digital assistants (PDAs). This application embodiment does not impose any restrictions on the specific type of terminal device.

[0046] In existing control methods for multi-unit refrigeration systems, multiple multi-unit refrigeration modules are connected in parallel to a loop pipeline, and each multi-unit refrigeration module is connected in series with a terminal system. Due to differences in the on-site installation pipelines, long operating time of components leading to changes in pressure drop, or differences in the flow rates of multiple refrigerant pumps at the same frequency and head, the refrigerant flow rate delivered by each refrigerant pump to the terminal system will be inconsistent. However, the gaseous refrigerant returning from the terminal system to each multi-unit refrigeration module is evenly distributed (the pressure at each gas pipe fulcrum in the loop pipeline is equal). This results in some multi-unit refrigeration modules having more liquid refrigerant in their receivers than other multi-unit refrigeration modules.

[0047] Furthermore, in practical industry applications, liquid receivers typically lack level sensors or other devices to obtain liquid level information. Therefore, the main control system cannot determine the liquid level in the receivers of each multi-unit cooling module. Consequently, when the data center load decreases, the main control system generally shuts down a multi-unit cooling module randomly or based on its operating time. This could lead to situations where a multi-unit cooling module with a high amount of liquid refrigerant in its receiver is shut down, locking a large amount of liquid refrigerant in that module and resulting in insufficient refrigerant in the remaining modules still in the cooling cycle.

[0048] When the refrigerant pressure at the inlet of the refrigerant pump is low or the subcooling is low, there will be a large amount of gaseous refrigerant at the pump inlet, leading to cavitation. Cavitation causes two main problems: firstly, it reduces the pump's head and the refrigerant flow rate, potentially causing refrigerant flow interruption, reducing the system's cooling capacity, and resulting in poorer temperature control at the server end. Secondly, cavitation can damage components such as the pump impeller, reducing system reliability and, in severe cases, causing pump failure.

[0049] Therefore, on the one hand, the existing control methods for multi-unit refrigeration systems make it difficult to maintain a completely consistent refrigerant flow rate from each refrigerant pump, resulting in varying liquid levels in the receivers of different multi-unit refrigeration modules. On the other hand, receivers in practical applications are generally not equipped with level sensors, and they are usually installed at the inlet of the refrigerant pump to provide a stable liquid level and continuous liquid flow, preventing gas intake. Therefore, when the data center load decreases, it is unavoidable to shut down a multi-unit refrigeration module with a high receiver level, leaving the remaining multi-unit refrigeration modules participating in the refrigeration cycle with less refrigerant, thus affecting the overall system stability.

[0050] Based on this, one embodiment of this application provides a control method for a multi-unit refrigeration system, which can avoid cavitation of the refrigerant pump without the need for devices such as liquid level sensors, thereby improving the operational reliability of the system.

[0051] Specifically, the multi-unit refrigeration system in this embodiment may include a terminal system and at least two parallel multi-unit refrigeration modules, each of which includes at least a liquid receiver and a refrigerant pump.

[0052] The terminal system can be configured indoors, connected in series with each multi-unit refrigeration module. The terminal system can consist of multiple evaporators connected in parallel, each evaporator equipped with an electronic expansion valve. At least two parallel multi-unit refrigeration modules can be configured outdoors to handle the cooling function. The structure of each multi-unit refrigeration module is not limited; it may include a liquid receiver and a refrigerant pump, as well as other components. Multiple multi-unit refrigeration modules can be configured in parallel, for example... Figure 1 As shown, the multi-unit refrigeration module includes multi-unit refrigeration module 1, ..., multi-unit refrigeration module N, where N is greater than or equal to 2.

[0053] As an example, each multi-unit refrigeration module includes at least a compressor, a mechanically cooled solenoid valve, a fan, a fan coil unit, a natural cooling solenoid valve, and a bypass solenoid valve; the compressor is located in the primary refrigeration circuit of the multi-unit refrigeration module; the mechanically cooled solenoid valve, fan coil unit, natural cooling solenoid valve, bypass solenoid valve, receiver-of-charge (RIC) and refrigerant pump are located in the secondary refrigeration circuit of the multi-unit refrigeration module; the fan is used to drive natural cooling air to exchange heat with the fan coil unit; the terminal system is connected in series with the secondary refrigeration circuit; the mechanically cooled solenoid valve, primary refrigeration circuit, receiver-of-charge (RIC), refrigerant pump and terminal system are connected in sequence to form... The system consists of a mechanical refrigeration cycle loop; a natural cooling solenoid valve, fan coil unit, receiver, refrigerant pump, and terminal system connected in sequence to form a natural cooling cycle loop; a mixed refrigeration cycle loop is formed by connecting the natural cooling solenoid valve, fan coil unit, primary side refrigeration circuit, receiver, refrigerant pump, and terminal system in sequence; a bypass solenoid valve is located between the mechanical cooling solenoid valve and the terminal system and is used to bypass the primary side refrigeration circuit, receiver, and refrigerant pump; when the multi-unit refrigeration module is in idle mode, the compressor, fan, and natural cooling solenoid valve are all closed, the mechanical cooling solenoid valve and bypass solenoid valve are open, and the refrigerant pump operates at the lowest frequency.

[0054] like Figure 1As shown, a multi-split refrigeration system can include indoor terminals (i.e., terminal systems), multi-split refrigeration module 1, and multi-split refrigeration module N. The indoor terminals can include multiple terminals connected in parallel, such as terminal 1, terminal 2, ..., terminal N. Each terminal can consist of an electronic expansion valve 1 and an evaporator 2. Each multi-split refrigeration module can be divided into a primary-side refrigeration circuit and a secondary-side refrigeration circuit. Taking multi-split refrigeration module 1 as an example, the primary-side refrigeration circuit of multi-split refrigeration module 1 can consist of a compressor 16, a condenser 17, an expansion valve 18, and a plate heat exchanger 8. The secondary-side refrigeration circuit of multi-split refrigeration module 1 can consist of a one-way valve 3, a mechanical cooling solenoid valve 4, a natural cooling solenoid valve 5, a fan coil unit 6, a plate heat exchanger 8, a bypass pipe 9, a liquid receiver 10, a refrigerant pump inlet pressure sensor 11, a refrigerant pump 12, a refrigerant pump outlet pressure sensor 13, a bypass solenoid valve 15, and a fan 19. The indoor terminals can be connected in series with the secondary-side refrigeration circuit.

[0055] In the specific refrigeration process, the mechanical cooling solenoid valve 4, the primary side refrigeration circuit, the liquid receiver 10, the refrigerant pump 12, and the indoor terminal can be connected in sequence to form a mechanical refrigeration cycle circuit. Thus, when the multi-unit refrigeration module is in the mechanical cooling state, the multi-unit refrigeration module can work according to the mechanical refrigeration cycle circuit to achieve the refrigeration function.

[0056] The natural cooling solenoid valve 5, fan coil unit 6, liquid receiver 10, refrigerant pump 12 and terminal system can be connected in sequence to form a natural cooling cycle loop. When the multi-unit refrigeration module is in the natural cooling state, the fan 19 drives the natural cooling air to exchange heat with the fan coil unit 6. The multi-unit refrigeration module can work according to the natural cooling cycle loop to achieve the cooling function.

[0057] The natural cooling solenoid valve 5, fan coil unit 6, primary side refrigeration circuit, liquid receiver 10, refrigerant pump 12 and terminal system can be connected in sequence to form a mixed refrigeration cycle circuit. Thus, when the multi-unit refrigeration module is in a mixed refrigeration state, the fan 19 drives the natural cooling air to exchange heat with the fan coil unit 6, and the multi-unit refrigeration module can work according to the mixed refrigeration cycle circuit to achieve the refrigeration function.

[0058] When the multi-unit refrigeration module is in idle mode, the compressor 16, fan 19, and natural cooling solenoid valve 5 can all be closed, while the mechanical cooling solenoid valve 4 and bypass solenoid valve 15 can be opened, and the refrigerant pump 12 can operate at the lowest frequency.

[0059] One embodiment of this application provides a control method for a multi-unit refrigeration system, which can be applied to terminal devices, such as... Figure 2 As shown, the method includes:

[0060] S101. When the cooling demand of the terminal system is less than the first preset value, at least one multi-unit refrigeration module is kept in operation, and shutdown logic is executed to shut down other multi-unit refrigeration modules; wherein, the shutdown logic includes at least: after transferring the refrigerant in the liquid receiver of the multi-unit refrigeration module executing the shutdown logic to the liquid receiver of other multi-unit refrigeration modules in operation, the refrigerant pump is turned off.

[0061] The first preset value is the cooling demand value for shutting down one or more multi-unit refrigeration systems. For example, if the first preset value satisfies the need to shut down one multi-unit refrigeration module, then the shutdown logic for shutting down one multi-unit refrigeration system is executed. If the first preset value satisfies the need to shut down two multi-unit refrigeration modules, then the shutdown logic for shutting down two multi-unit refrigeration systems is executed, and so on. Furthermore, when executing the shutdown logic for two or more multi-unit refrigeration modules, the shutdown logic can be executed one by one or simultaneously. In this embodiment, it is preferred to execute the shutdown logic one by one, that is, first shut down one multi-unit refrigeration module, and after the shutdown logic of that multi-unit refrigeration module is completed, then the shutdown logic of another multi-unit refrigeration module is executed.

[0062] The specific shutdown logic may include at least the following: after transferring the refrigerant in the receiver of the multi-unit refrigeration module that is executing the shutdown logic to the receiver of other multi-unit refrigeration modules that are in operation, the refrigerant pump is then turned off.

[0063] The specific means by which the terminal device controls the refrigerant in the receiver of the multi-unit refrigeration module executing the shutdown logic to be transferred to the receivers of other multi-unit refrigeration modules in operation is not limited. For example, the refrigerant in the receiver of the multi-unit refrigeration module executing the shutdown logic can be transferred to the receivers of other multi-unit refrigeration modules in operation by adjusting the operating frequency of the refrigerant pump within the multi-unit refrigeration module. Specifically, the operating frequency of the refrigerant pump in the multi-unit refrigeration module executing the shutdown logic can be controlled to be higher than the operating frequency of the refrigerant pumps in other normally operating multi-unit refrigeration modules. Thus, because... The refrigerant pump executing the shutdown logic operates at a higher frequency than the refrigerant pumps of the other multi-split refrigeration modules. This means that the liquid refrigerant flow rate output by the refrigerant pump is greater than that of the refrigerant pumps in the other multi-split refrigeration modules. Since the amount of gaseous refrigerant input allocated to each multi-split refrigeration module from the indoor system terminal air conditioner is equal, the liquid level in the receiver of the multi-split refrigeration module executing the shutdown logic will gradually decrease, while the liquid level in the receivers of the other multi-split refrigeration modules will gradually increase. This allows the refrigerant in the receiver of the multi-split refrigeration module executing the shutdown logic to be transferred to the receivers of the other multi-split refrigeration modules that are in operation.

[0064] In one possible implementation, each multi-unit refrigeration module includes at least a compressor, a mechanical cooling solenoid valve, a fan, and a natural cooling solenoid valve. The shutdown logic may specifically include: first shutting down the compressor and fan, then transferring the refrigerant in their receivers to the receivers of other operating multi-unit refrigeration modules, shutting down the refrigerant pump, and finally shutting down the mechanical cooling solenoid valve and / or the natural cooling solenoid valve. If the shutdown logic is executed when the multi-unit refrigeration module is in mechanical cooling mode, since the natural cooling solenoid valve is closed in this state, the mechanical cooling solenoid valve only needs to be closed last. If the shutdown logic is executed when the multi-unit refrigeration module is in natural cooling mode, since the mechanical cooling solenoid valve is closed in this state, the natural cooling solenoid valve only needs to be closed last. If both the mechanical cooling solenoid valve and the natural cooling solenoid valve are open when the multi-unit refrigeration module executes the shutdown logic, then both the mechanical cooling solenoid valve and the natural cooling solenoid valve need to be closed simultaneously.

[0065] One implementation is that when the load on the end systems in the data center decreases, i.e., the cooling demand is relatively small, the cooling output of the multi-unit cooling modules decreases accordingly until it meets the requirement to shut down a certain multi-unit cooling module: when the cooling output devices of the multi-unit cooling module, such as compressors and fans, are all turned off, and the cooling demand is less than the preset cooling shutdown demand for a continuous preset cooling shutdown period, the main control system collects the number of multi-unit cooling modules with refrigerant pumps currently in operation in real time, and executes the following logic:

[0066] When the number of multi-unit cooling modules is ≥2, the main control system issues a command to randomly shut down one multi-unit cooling module. The multi-unit cooling module that receives the command executes the shutdown logic. If, after shutting down one multi-unit cooling module, the cooling demand is again less than the preset cooling shutdown demand within the preset cooling shutdown time, the system issues another command to shut down a module. The multi-unit cooling module that receives the command executes the shutdown logic, and so on, until the number of the last remaining multi-unit cooling module still meets the requirement that the cooling demand is less than the preset cooling shutdown demand within the preset cooling shutdown time. Then, that multi-unit cooling module enters idle mode.

[0067] When the number of multi-unit refrigeration modules is 1, if the refrigeration demand is less than the preset refrigeration shutdown demand during the continuous preset refrigeration shutdown time, then the multi-unit refrigeration module will execute the logic to enter the idle mode.

[0068] In this embodiment, the method for calculating the cooling demand value is not limited. As an example, the terminal device can obtain the inlet pressure value of the refrigerant delivery equipment in the multi-split refrigeration system and calculate the current cooling demand value according to (inlet pressure value - preset pressure value - preset control dead zone value) / cooling control ratio. Here, the preset pressure value, preset control dead zone value, and cooling control ratio can be pre-set fixed values. For example, the preset pressure value can be a pre-set pressure threshold value. The preset control dead zone value can refer to a parameter fluctuation range set in the terminal device within an allowable range. When the actual parameter (such as pressure value) is within this range, the terminal device will not trigger start / stop or adjustment actions, thereby avoiding frequent start / stop of the multi-split refrigeration system, reducing mechanical wear and energy consumption, and ensuring stable system operation. The cooling control ratio can refer to the ratio between the rated cooling capacity of the indoor unit and the rated cooling capacity of the outdoor unit, typically used to ensure efficient operation of the multi-split refrigeration system under different operating conditions.

[0069] In this embodiment, by transferring the refrigerant in the receiver of the multi-unit refrigeration module executing the shutdown logic to the receiver of other multi-unit refrigeration modules in operation, and then shutting off the refrigerant pump, cavitation of the multi-unit refrigeration modules in operation can be avoided, while improving their cooling effect, thereby enhancing the stability of the multi-unit refrigeration system.

[0070] As another example, after executing the shutdown logic to shut down other multi-unit cooling modules, and only one multi-unit cooling module is running, if the cooling demand of the terminal system is less than the second preset value, the running multi-unit cooling module will be switched to idle mode.

[0071] The second preset value is the cooling demand value for shutting down the last multi-unit refrigeration module. That is, when the cooling demand of the terminal system is less than the second preset value, none of the multi-unit refrigeration modules need to output cooling capacity. The last running multi-unit refrigeration module can be put into idle mode. In this way, when the cooling demand increases, the multi-unit refrigeration module in idle mode can be quickly switched to cooling mode to meet the needs of the application scenario. At the same time, keeping at least one refrigerant pump running when there is no cooling output can keep the refrigerant circulating between indoors and outdoors, and the temperature difference between indoors and outdoors will not be too large.

[0072] By switching one of the multi-unit cooling modules that was not shut down to idle mode, the overall energy consumption of the system is reduced. At the same time, when the cooling demand increases in the future, the multi-unit cooling system can be switched to cooling mode in real time and quickly to achieve better temperature control.

[0073] In this embodiment, the idle mode can be defined as a mode that is not in the cooling output stage. That is, when the multi-unit refrigeration module is running in idle mode, the compressor, fan, and natural cooling solenoid valve are all closed, the mechanical cooling solenoid valve and bypass solenoid valve are open, and the refrigerant pump runs at the lowest frequency.

[0074] As a specific optional embodiment of switching from cooling state to idle mode, controlling the multi-unit cooling module to operate in idle mode according to the cooling state of the multi-unit cooling module includes:

[0075] If the multi-unit refrigeration module is in natural cooling or mixed cooling mode, the multi-unit refrigeration module controlling the operation mode will open the mechanical cooling solenoid valve and close the natural cooling solenoid valve after a set time of opening the mechanical cooling solenoid valve; the multi-unit refrigeration module controlling the operation mode will open the bypass solenoid valve and set the current bypass step of the bypass solenoid valve to the preset idle bypass step.

[0076] The set duration can be used to control the closing of the natural cooling solenoid valve. The preset idle bypass steps can be a pre-set number of idle bypass steps, which refers to the number of steps corresponding to the position of the valve needle in the idle state of the bypass solenoid valve. The specific values ​​of the set duration and preset idle bypass steps can be configured by relevant personnel according to actual needs.

[0077] Natural cooling solenoid valves are mainly used in natural cooling conditions, such as... Figure 1 As shown, the natural cooling solenoid valve 5, fan coil unit 6, liquid receiver 10, refrigerant pump 12 and terminal system can be connected in sequence to form a natural cooling cycle loop. When the multi-unit refrigeration module is in the natural cooling state, the fan 19 drives the natural cooling air to exchange heat with the fan coil unit 6. The multi-unit refrigeration module can work according to the natural cooling cycle loop to achieve the cooling function.

[0078] Mechanically cooled solenoid valves are mainly used in mechanically cooled or refrigerated conditions, such as... Figure 1 As shown, the mechanical cooling solenoid valve 4, the primary cooling circuit, the liquid receiver 10, the refrigerant pump 12, and the indoor terminal can be connected in sequence to form a mechanical cooling cycle circuit. Thus, when the multi-unit refrigeration module is in mechanical cooling state, the multi-unit refrigeration module can work according to the mechanical cooling cycle circuit to achieve the cooling function.

[0079] In a mixed cooling and refrigeration state, such as Figure 1 As shown, the natural cooling solenoid valve 5, fan coil unit 6, primary side refrigeration circuit, liquid receiver 10, refrigerant pump 12 and terminal system can be connected in sequence to form a mixed refrigeration cycle circuit. Thus, when the multi-unit refrigeration module is in the mixed refrigeration state, the fan 19 drives the natural cooling air to exchange heat with the fan coil unit 6, and the multi-unit refrigeration module can work according to the mixed refrigeration cycle circuit to achieve the refrigeration function.

[0080] In a specific implementation, if the multi-unit refrigeration module is in either natural cooling or mixed cooling mode, it indicates that the natural cooling solenoid valve of the multi-unit refrigeration module is open. In this case, the multi-unit refrigeration module can be controlled to open the corresponding mechanical cooling solenoid valve, and after a set duration of opening the mechanical cooling solenoid valve, the multi-unit refrigeration module can be controlled to close the natural cooling solenoid valve. Additionally, the multi-unit refrigeration module can be controlled to open the bypass solenoid valve, and the current bypass step count of the bypass solenoid valve can be set to a preset idle bypass step count. Based on this, it is possible to ensure that the multi-unit refrigeration system maintains a stable operating state when switching to an idle state in either natural cooling or mixed cooling mode, thereby ensuring a rapid switch back to cooling mode and achieving better temperature control.

[0081] If the multi-unit refrigeration module is in mechanical cooling mode, the multi-unit refrigeration module controlling the operation mode will open the bypass solenoid valve and set the current bypass step of the bypass solenoid valve to the preset idle bypass step.

[0082] In a specific implementation, if the refrigeration state is mechanical cooling, it means that the mechanical cooling solenoid valve of the multi-unit refrigeration module is in the open state. In this case, the multi-unit refrigeration module can be directly controlled to open the bypass solenoid valve, and the current bypass step of the bypass solenoid valve can be set to the preset idle bypass step.

[0083] like Figure 3 As shown, when the data center load decreases, that is, when the cooling demand of the terminal system is less than the cooling shutdown demand value of the multi-unit cooling module, the output cooling capacity of the multi-unit cooling module decreases accordingly until it meets the requirement to shut down a certain multi-unit cooling module. That is, if the cooling demand is less than the cooling shutdown demand value within a preset shutdown time T, and the cooling output devices (such as compressors and fans) of the multi-unit cooling module are not all shut down, the compressor and fan can be shut down.

[0084] With the compressor and fan off, the main control system (i.e., the terminal device) can collect the number of all currently running multi-unit refrigeration modules in real time (i.e., the number of modules in operation). When the number of modules in operation is ≥2, the main control system can issue a command to randomly shut down one multi-unit refrigeration module. The multi-unit refrigeration module that receives the command will execute the shutdown logic. If, after shutting down one multi-unit refrigeration module, the cooling demand is less than the cooling shutdown demand value for a continuous preset downtime, the above operation can be repeated, and when the number of modules in operation is ≥2, a command to shut down another multi-unit refrigeration module will be issued. The multi-unit refrigeration module that receives the command will execute the shutdown logic, and so on, until the last multi-unit refrigeration module is in operation, i.e., the number of modules in operation = 1.

[0085] When the number of modules running is 1, if the cooling demand within the preset downtime is less than the cooling downtime demand value, the multi-unit cooling module can be controlled to enter idle mode (or standby mode) logic.

[0086] like Figure 4 As shown, when the conditions for entering the idle mode are met, it can be determined whether the natural cooling solenoid valve is in the open state. If the natural cooling solenoid valve is in the open state, that is, the refrigeration state before entering the idle mode is natural cooling or mixed cooling state, then the main control system can issue a command to open the mechanical cooling solenoid valve for 5 seconds and then close the natural cooling solenoid valve, and open the bypass solenoid valve to the preset idle bypass step number. At this time, the multi-unit refrigeration module enters the idle mode.

[0087] If the natural cooling solenoid valve is not in the open state, that is, the refrigeration state before entering the idle mode is the mechanical cooling state, and the mechanical cooling solenoid valve is in the open state, the main control system can send a command to open the bypass solenoid valve to the preset idle bypass step number, at which time the multi-unit refrigeration module enters the idle mode.

[0088] In one possible implementation, when the multi-unit cooling module is in idle mode, the method further includes: when the cooling demand of the terminal system is greater than a third preset value, obtaining the outdoor ambient temperature of the multi-unit cooling system; and controlling the multi-unit cooling module to switch from idle state to cooling state based on the outdoor ambient temperature.

[0089] The third preset value can refer to a pre-set demand value, which is used to determine whether it is necessary to perform a cooling operation on the multi-unit cooling module, such as controlling the multi-unit cooling module to switch from an idle state to a cooling state. The specific value can be configured based on empirical values.

[0090] After controlling the multi-unit cooling module to operate in idle mode, the terminal device can continue to monitor the cooling demand of the terminal system to achieve precise control of the multi-unit cooling system according to the actual situation. If the cooling demand of the terminal system is greater than the cooling start-up demand value (i.e., the third preset value), the outdoor ambient temperature of the multi-unit cooling system can be obtained, and the multi-unit cooling module can be controlled to switch from idle state to cooling state according to the different outdoor ambient temperatures.

[0091] As an example, the refrigeration state includes one of the following: natural cooling state, mechanical cooling state, and mixed cooling state; in the natural cooling state, the compressor, mechanical cooling solenoid valve, and bypass solenoid valve are closed, the natural cooling solenoid valve is open, and the fan and refrigerant pump operate at preset frequencies; in the mechanical cooling state, the fan, natural cooling solenoid valve, and bypass solenoid valve are closed, the mechanical cooling solenoid valve is open, and the compressor and refrigerant pump operate at preset frequencies; in the mixed cooling state, the mechanical cooling solenoid valve and bypass solenoid valve are closed, the natural cooling solenoid valve is open, and the compressor, fan, and refrigerant pump operate at preset frequencies.

[0092] In a specific implementation, if the outdoor ambient temperature is lower than the preset natural cooling temperature, it means that the current outdoor ambient temperature is lower than the maximum critical value corresponding to the natural cooling state. Therefore, the multi-unit refrigeration module can be controlled to enter the natural cooling state. Specifically, the natural cooling state can be characterized by: the compressor, mechanical cooling solenoid valve, and bypass solenoid valve being closed; the natural cooling solenoid valve being open; and the fan and refrigerant pump operating at preset frequencies. The specific control process may include, for example, controlling the multi-unit refrigeration module to open the natural cooling solenoid valve, and after a preset duration of opening the natural cooling solenoid valve, closing the mechanical cooling solenoid valve, compressor, and bypass solenoid valve; and controlling the fan and refrigerant pump to operate at preset frequencies. For instance, the operating frequency of the refrigerant pump in the multi-unit refrigeration module can be controlled based on the preset inlet and outlet pressure difference, and the delivery frequency of the fan in the multi-unit refrigeration module can be controlled based on the inlet pressure value.

[0093] In a specific implementation, if the outdoor ambient temperature is greater than the preset natural cooling temperature and less than the preset mechanical cooling temperature, it indicates that the current outdoor ambient temperature is greater than the maximum critical value corresponding to the natural cooling state and less than the minimum critical value corresponding to the mechanical cooling state. Therefore, the multi-unit refrigeration module can be controlled to enter a mixed cooling state. Specifically, the mixed cooling state can be characterized by: the mechanical cooling solenoid valve and bypass solenoid valve being closed, the natural cooling solenoid valve being open, and the compressor, fan, and refrigerant pump operating at preset frequencies. The specific control process may include, for example, controlling the multi-unit refrigeration module to open the natural cooling solenoid valve, closing the mechanical cooling solenoid valve after a preset duration of opening the natural cooling solenoid valve, and closing the bypass solenoid valve; controlling the compressor, fan, and refrigerant pump to operate at preset frequencies, such as controlling the refrigerant pump's operating frequency based on the preset inlet and outlet pressure difference, controlling the fan's delivery frequency based on the inlet pressure value, and controlling the compressor's delivery frequency based on the current cooling demand value.

[0094] In a specific implementation, if the outdoor ambient temperature is greater than the preset mechanical cooling temperature, it means that the current outdoor ambient temperature is greater than the minimum critical value corresponding to the mechanical cooling state. In this case, the multi-unit refrigeration module can be controlled to enter the mechanical cooling state. Specifically, the mechanical cooling state can be characterized by the fan, natural cooling solenoid valve, and bypass solenoid valve being closed, the mechanical cooling solenoid valve being open, and the compressor and refrigerant pump operating at preset frequencies. The specific control process may include, for example, controlling the fan, natural cooling solenoid valve, and bypass solenoid valve to be closed, controlling the operating frequency of the refrigerant pump in the multi-unit refrigeration module according to the preset inlet and outlet pressure difference, and controlling the delivery frequency of the compressor in the multi-unit refrigeration module according to the current cooling demand value.

[0095] like Figure 5 As shown, when the data center load increases, i.e., the cooling demand is relatively large, the multi-unit cooling module needs to exit the idle mode and switch to the cooling output stage, i.e., the cooling state. Specifically, when the multi-unit cooling module meets the conditions for exiting the idle mode, such as the refrigerant pump of the idle mode module is in operation and the cooling demand is greater than the preset single module cooling start-up demand (i.e., the third preset value), the main control system can collect the outdoor ambient temperature in real time and determine which corresponding cooling state to enter based on the outdoor ambient temperature.

[0096] If the outdoor ambient temperature is higher than the preset mechanical cooling state entry temperature, the main control system can issue a command to close the bypass solenoid valve to step 0, and control the operating frequency of the refrigerant pump according to the preset target pressure difference between the inlet and outlet of the refrigerant pump, and control the operating frequency of the compressor according to the main control PID calculation value (i.e., cooling demand). At this time, the multi-unit refrigeration module enters the mechanical cooling state.

[0097] If the outdoor ambient temperature is lower than the preset natural cooling state entry temperature, the main control system can issue a command to open the natural cooling solenoid valve for 5 seconds (adjustable) and then close the mechanical cooling solenoid valve. At the same time, the bypass solenoid valve is closed to step 0. The main control system controls the operating frequency of the refrigerant pump according to the preset target pressure difference between the inlet and outlet of the refrigerant pump, and controls the speed of the fan according to the inlet pressure. At this time, the multi-unit refrigeration module enters the natural cooling state.

[0098] If the preset natural cooling state entry temperature is less than the outdoor ambient temperature and the preset mechanical cooling state entry temperature, the main control system can issue a command to open the natural cooling solenoid valve for 5 seconds (adjustable) and then close the mechanical cooling solenoid valve. At the same time, the bypass solenoid valve is closed to step 0. The main control system controls the refrigerant pump operating frequency according to the preset target pressure difference between the inlet and outlet of the refrigerant pump, controls the fan speed according to the inlet pressure, and controls the compressor operating frequency according to the main control PID (i.e., cooling demand) calculation value. At this time, the multi-unit refrigeration module enters the mixed cooling state.

[0099] Figure 6This is a flowchart illustrating a control method for a multi-unit refrigeration system according to another embodiment of this application. In this embodiment, after the refrigerant in the receiver of the multi-unit refrigeration module executing the shutdown logic is delivered to the receivers of other multi-unit refrigeration modules in operation, the refrigerant pump is turned off. It is further optimized as follows: the first refrigerant pump of the multi-unit refrigeration module executing the shutdown logic is increased to a first preset frequency for operation, and the second refrigerant pump of the other multi-unit refrigeration modules in operation is operated at an average frequency, wherein the first preset frequency is greater than the average frequency.

[0100] After running for the first preset time, it is determined whether the pressure difference between the inlet and outlet of the first fluorine pump is less than or equal to the preset target pressure difference. If the pressure difference between the inlet and outlet of the first fluorine pump is less than or equal to the preset target pressure, the original frequency operation of the first and second fluorine pumps is restored, and then the first fluorine pump is shut down.

[0101] If the pressure difference between the inlet and outlet of the first fluorine pump is greater than the preset target pressure difference, the first fluorine pump will be increased to the second preset frequency, and the other second fluorine pumps will operate at the average frequency, wherein the second preset frequency is greater than the first preset frequency; after operating for the second preset time, when the pressure difference between the inlet and outlet of the first fluorine pump is less than or equal to the preset target pressure difference, the original frequency operation of the first and second fluorine pumps will be restored, and then the first fluorine pump will be shut down.

[0102] For example, taking a centrifugal pump as an example, such as... Figure 7 As shown, the main control system can collect the operating frequencies of the refrigerant pumps from each operating module, sum them to obtain the total operating frequency of the refrigerant pumps, and then issue a command to shut down one multi-unit refrigeration module. For example, it issues a command to the refrigerant pump of the multi-unit refrigeration module that needs to execute shutdown logic to increase the frequency to the preset refrigerant pump discharge frequency 1 (i.e., the first preset frequency). The operating frequency of the refrigerant pumps of the other modules is calculated as (total refrigerant pump operating frequency - refrigerant pump discharge frequency 1) / number of modules in operation - 1 (i.e., average frequency). After running the preset refrigerant pump shutdown and discharge time 1 (i.e., the first preset time), the following judgment is made:

[0103] ① If the pressure difference between the inlet and outlet of the refrigerant pump of the multi-unit refrigeration module that needs to execute the shutdown logic is less than or equal to the target pressure difference for liquid discharge (i.e., the preset target pressure difference), the main control system first distributes the total operating frequency of the refrigerant pumps equally to each refrigerant pump, that is, makes the operating frequency of the refrigerant pumps of all multi-unit refrigeration modules = the total operating frequency of the refrigerant pumps / the number of modules in operation. Then, after restoring the original operating frequency of each refrigerant pump, the refrigerant pumps and the solenoid valves of the modules that need to be shut down are closed, thereby completing the shutdown logic.

[0104] ② If the pressure difference between the inlet and outlet of the refrigerant pump in the multi-unit refrigeration module that needs to be shut down is greater than the target pressure difference for draining liquid, the refrigerant pump of the module that needs to be shut down will be frequency-upgraded to the preset refrigerant pump draining frequency 2 (i.e., the second preset frequency), and the refrigerant pump will continue to run for a draining time 2 (i.e., the second preset time). When the pressure difference between the inlet and outlet of the refrigerant pump in the multi-unit refrigeration module that executes the shutdown logic is less than or equal to the target pressure difference for draining liquid, the main control system can first distribute the total operating frequency of the refrigerant pump to the refrigerant pump of each multi-unit refrigeration module, that is, the operating frequency of the refrigerant pump of all multi-unit refrigeration modules = the total operating frequency of the refrigerant pump / the number of modules in operation. Then, after restoring the original operating frequency of each refrigerant pump, the refrigerant pump of the module that needs to be shut down and the solenoid valve for natural cooling / mechanical cooling are closed, thereby completing the shutdown logic.

[0105] If the pressure difference between the inlet and outlet of the refrigerant pump is still greater than the target pressure difference for draining, the refrigerant pump of the multi-unit refrigeration module that is executing the shutdown logic can continue to increase its frequency. This process continues until the pressure difference between the inlet and outlet of the refrigerant pump of the multi-unit refrigeration module is less than or equal to the target pressure difference for draining. After restoring the original operating frequency of each refrigerant pump, the refrigerant pump and the solenoid valve of the module that needs to be shut down are then closed, thus completing the shutdown logic.

[0106] It should be noted that because the refrigerant pump executing the shutdown logic operates at a higher frequency than the refrigerant pumps in other modules, meaning the liquid refrigerant flow rate output by the refrigerant pump is greater than that of the refrigerant pumps in other modules, and the amount of gaseous refrigerant input allocated to each multi-split refrigeration module from the indoor terminal air conditioner is equal (the pressure at each gas pipe fulcrum in the ring pipeline is equal), the liquid level in the receiver of the module executing the shutdown logic will gradually decrease, while the liquid level in the receiver of the other modules will gradually increase. Simultaneously, the draining process is divided into two stages. After the first stage is completed, it is determined whether there is still liquid refrigerant in the receiver by checking if the pressure difference between the inlet and outlet of the refrigerant pump is less than the target pressure difference for draining the refrigerant pump. If there is still liquid refrigerant, the frequency of the refrigerant pump executing the shutdown can be increased until the pressure difference between the inlet and outlet of the refrigerant pump is less than the target pressure difference for draining the refrigerant pump. Through the above two aspects, the liquid refrigerant in the receiver of the module that needs to be shut down is distributed to the receiver of the remaining modules that need to be kept on as much as possible. This avoids the problem of locking a large amount of liquid refrigerant in the receiver of the module that needs to be shut down, resulting in less refrigerant in the remaining modules that need to be kept on, and improves the operational stability of the entire system.

[0107] If, during the refrigerant pump discharge time 2, the pressure difference between the inlet and outlet of the refrigerant pump in the module requiring shutdown is less than or equal to the target discharge pressure difference, the main control system can immediately distribute the total operating frequency of the refrigerant pumps equally to each refrigerant pump. That is, the operating frequency of each refrigerant pump = the total operating frequency of the refrigerant pumps / the number of modules in operation. After each refrigerant pump restores its original operating frequency, the refrigerant pumps and the solenoid valves for natural cooling / mechanical cooling of the multi-unit refrigeration module requiring shutdown are then shut down, thereby completing the shutdown logic.

[0108] As an example, when the first fluorine pump is a gear pump, the first preset frequency is set to be 5-15 Hz higher than the average frequency; when the first fluorine pump is a centrifugal pump, the first preset frequency is set to be at least 20 Hz higher than the average frequency.

[0109] Another embodiment is that, taking a gear pump as an example, the shutdown logic can be optimized according to the structural characteristics of the gear pump. For example, after the main control system collects the operating frequency of the refrigerant pumps of each operating module, it can issue a command to the refrigerant pump of the module that needs to execute the shutdown logic to increase the frequency to the lowest refrigerant pump operating frequency in the remaining multi-unit refrigeration modules + 10Hz, and continue to run the preset refrigerant pump shutdown drainage time 1. When the pressure difference between the inlet and outlet of the refrigerant pump is less than or equal to the drainage target pressure difference, the original operating frequency of each refrigerant pump is restored, and the refrigerant pump and the natural cooling solenoid valve are closed, thereby completing the shutdown logic.

[0110] Due to its structural characteristics, gear pumps do not need to operate at a high frequency (40-60Hz or higher) to quickly discharge the liquid refrigerant from the receiver within a few minutes. Therefore, when the refrigerant pump is a gear pump, it is only necessary to set the operating frequency of the refrigerant pump that needs to execute the shutdown logic module to be 10Hz higher than the lowest operating frequency of the refrigerant pumps in the other operating multi-unit refrigeration modules, and there is no need to perform the liquid discharge in stages.

[0111] It should be noted that if the gear pump operates at too high a frequency and discharges liquid too quickly, the gear pump will run dry (if there is no continuous liquid refrigerant at the inlet). This will increase the friction on the gear meshing surface, increase noise, and may damage the gear pump. Therefore, the control logic can be optimized according to the above operation.

[0112] Taking the control of two multi-unit refrigeration modules equipped with centrifugal pumps operating in a natural cooling state as an example, the control method of a multi-unit refrigeration system provided in this embodiment is described below as an example:

[0113] Low-load phase at the terminal: If the cooling demand of the indoor terminal air conditioner is low, the fans of the two multi-split refrigeration modules can be slowly reduced in speed until they are turned off. If the main control system still detects low cooling demand, it needs to issue a command to shut down one multi-split refrigeration module. Assuming that multi-split refrigeration module 1 needs to be shut down, the main control system can first collect the refrigerant pump operating frequencies of each operating module and sum the total refrigerant pump operating frequencies. Then, it can instruct the refrigerant pump 12 of multi-split refrigeration module 1 to increase its frequency to the preset refrigerant pump discharge frequency 1. The refrigerant pump operating frequency of multi-split refrigeration module 2 = (total refrigerant pump operating frequency - refrigerant pump discharge frequency 1) / number of operating modules - 1 (the first refrigerant pump of the multi-split refrigeration module that is about to execute the shutdown logic will increase its frequency to the first preset frequency, and the second refrigerant pump of other multi-split refrigeration modules that are in operation will operate at the average frequency). After multi-split refrigeration module 1 has been running for the preset refrigerant pump shutdown discharge time 1, it will detect the refrigerant pump operating at the refrigerant pump discharge frequency 1. If the inlet and outlet pressure difference of the refrigerant pump in the multi-unit refrigeration module 1 is greater than the preset target pressure difference for refrigerant pump drainage, then the refrigerant pump in the multi-unit refrigeration module 1 will be frequency-increased to the preset refrigerant pump drainage frequency 2 (i.e., when the inlet and outlet pressure difference of the first refrigerant pump is greater than the preset target pressure difference, the first refrigerant pump will be frequency-increased to the second preset frequency). After the refrigerant pump shutdown drainage time 2 is continuously run, when the inlet and outlet pressure difference of the refrigerant pump is less than or equal to the preset target pressure difference for refrigerant pump drainage, the main control system can first evenly distribute the total operating frequency of the refrigerant pump to each refrigerant pump, i.e., the operating frequency of each refrigerant pump = total operating frequency of refrigerant pump / number of modules. After restoring the original operating frequency of each refrigerant pump, the refrigerant pump and the natural cooling solenoid valve of the multi-unit refrigeration module 1 can be shut down (i.e., when the inlet and outlet pressure difference of the first refrigerant pump is less than or equal to the preset target pressure difference, after restoring the original operating frequency of the first and second refrigerant pumps, the first refrigerant pump is shut down), thus completing the shutdown logic.

[0114] Terminal cooling exit phase: When the cooling demand of the indoor terminal air conditioner meets the cooling exit condition, the terminal electronic expansion valve 1 closes. When the main control system collects data showing that the cooling demand within the preset shutdown time is less than the cooling shutdown demand value, the multi-split refrigeration module 2 can execute the idle mode logic (i.e., after executing the shutdown logic to shut down other multi-split refrigeration modules, and only one multi-split refrigeration module is in operation, when the cooling demand of the terminal system is less than a second preset value, the operating multi-split refrigeration module is switched to idle mode). For example, the main control system can issue a command to the multi-split refrigeration module 2 to open the mechanical cooling solenoid valve for 5 seconds and then close the natural cooling solenoid valve, and open the bypass solenoid valve to a preset idle bypass step number (e.g., 480 steps fully open). At this time, the multi-split refrigeration module enters the idle mode. Liquid refrigerant can circulate internally within the multi-split refrigeration module in the loop of refrigerant pump 12 - bypass solenoid valve 15 - plate heat exchanger 8 - receiver 10.

[0115] The terminal air conditioner re-enters the cooling stage: After a certain period of time, if the data center server load increases, the indoor terminal air conditioner can enter the cooling state. The terminal electronic expansion valve opens, and liquid refrigerant flows into the indoor terminal evaporator for evaporation. After passing through the mechanical solenoid valve, it flows through the plate heat exchanger. Since the multi-split refrigeration module 2 is in idle mode, the compressor is off at this time, and the multi-split refrigeration module has no cooling output. Therefore, the pressure read by the refrigerant pump inlet pressure will slowly rise, that is, the cooling demand of the multi-split refrigeration module increases. When the multi-split main control system collects the cooling demand, which is greater than the preset single-module cooling start-up demand, the main control system collects the current outdoor ambient temperature (e.g., -5℃) in real time (i.e., in the terminal system). When the overall cooling demand exceeds a third preset value, the outdoor ambient temperature of the multi-unit refrigeration system is obtained. Based on the outdoor ambient temperature, the multi-unit refrigeration module is switched from the idle state to the cooling state. Assuming it is determined that a natural cooling state is required, the main control system can issue a command to open the natural cooling solenoid valve for 5 seconds and then close the mechanical cooling solenoid valve. At the same time, the bypass solenoid valve is closed from step 480 to step 0. The main control system controls the operating frequency of the refrigerant pump according to the preset target pressure difference between the inlet and outlet of the refrigerant pump, and controls the fan speed according to the inlet pressure of the refrigerant pump. At this time, the multi-unit refrigeration module enters the natural cooling state (i.e., the multi-unit refrigeration module is switched from the idle state to the cooling state based on the outdoor ambient temperature).

[0116] Furthermore, when the refrigerant pumps of the two multi-split refrigeration modules are equipped with gear pumps, the execution of the shutdown logic can be optimized. For example, during low-load phases at the terminal, if the cooling demand of the indoor terminal air conditioner is small, the fans of the two multi-split refrigeration modules will slowly reduce their speed until they shut down. If the main control system still detects that the cooling demand is small, it needs to issue a shutdown order for one multi-split refrigeration module. Assuming multi-split refrigeration module 1 is shut down, the main control first collects the operating frequency of the refrigerant pumps of each operating module and raises the refrigerant pump frequency to the lowest operating frequency among the remaining multi-split refrigeration modules + 10Hz (assuming the operating frequency of the refrigerant pump in multi-split refrigeration module 2 is 20Hz, then raising the frequency to 30Hz is sufficient). After continuously running the preset refrigerant pump shutdown and drainage time 1, refrigerant pump 12 and the natural cooling solenoid valve 5 are shut down, completing the shutdown logic. It can be observed that when drainage is performed according to this shutdown logic, the drainage speed is fast.

[0117] As can be seen from the above description, the control method of the multi-unit refrigeration system provided in this embodiment enables the multi-unit refrigeration module that needs to be shut down to execute shutdown logic without relying on any other devices such as liquid level sensors to monitor the liquid level of the receiver. Through a phased liquid drainage logic, the liquid refrigerant in the receiver of the module is distributed to the remaining modules that need to be kept on to the maximum extent. This ensures that there is a relatively stable liquid refrigerant level and continuous liquid flow in the receivers of the remaining modules, avoiding the problem of "cavitation" of the refrigerant pump and refrigerant interruption caused by the pressure drop in the receiver due to the outdoor ambient temperature or other influencing factors.

[0118] Meanwhile, when the data center has no cooling demand, the last multi-unit cooling module executes the idle mode logic, and the refrigerant continues to circulate within the module, ensuring that the multi-unit cooling module is always in an internal bypass circulation state; when the data center load increases, the multi-unit cooling module can respond quickly in real time, switch to cooling mode to output cooling capacity, and achieve better temperature control.

[0119] Furthermore, since multi-split refrigeration systems using refrigerant pumps are typically used in applications where the indoor and outdoor units have long transmission distances, the multi-split refrigeration modules and the indoor terminal air conditioners generally do not communicate in practice (e.g., due to long communication distances, susceptibility to interference from other high-power devices). However, in idle mode, the mechanical cooling solenoid valve is open, and both the compressor and the fan of the multi-split refrigeration module are off. At this time, the module does not output cooling capacity. Therefore, by calculating the cooling demand, it is possible to promptly determine whether the multi-split refrigeration module needs to switch from idle mode to cooling mode.

[0120] The control method for the multi-unit refrigeration system provided in this embodiment is also applicable to multi-unit refrigeration systems that use gear pumps as refrigerant delivery devices. Although gear pumps have a certain venting capacity, they produce significant noise when air bubbles are present at the pump inlet. Prolonged exposure to a non-pure liquid environment can also cause wear on the gear pump's meshing surfaces, potentially leading to pump damage. The refrigerant delivery device in a refrigerant pump multi-unit refrigeration system can be implemented in various ways, not limited to centrifugal pumps and gear pumps. Any instance where only the refrigerant delivery device is replaced without changing the core control method should be covered within the scope of this application.

[0121] Therefore, the control method for the multi-unit refrigeration system provided in this embodiment provides multiple safeguards for the entire fluorine pump multi-unit refrigeration system to avoid problems such as fluorine pump cavitation, refrigerant interruption, and timely cooling output. While improving system stability, it provides a complete set of control logic for the start-up and shutdown of the fluorine pump multi-unit refrigeration system and the distribution of module cooling output.

[0122] This application also provides a terminal device. Figure 8 This is a schematic diagram of the structure of a terminal device provided in one embodiment of this application, as shown below. Figure 8 As shown, the terminal device includes: at least one processor 401, a memory 402, an input device 403, an output device 404, and a computer program stored in the memory 402 and executable on at least one processor 401. When the processor 401 executes the computer program, it implements the steps in any of the above-described method embodiments.

[0123] Input device 403 can be used to receive input digital or character information, and to generate key signal inputs related to user settings and function control of the terminal device. Output device 404 may include display devices such as a display screen.

[0124] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A control method for a multi-unit refrigeration system, characterized in that, The multi-unit refrigeration system includes a terminal system and at least two parallel multi-unit refrigeration modules, each of the multi-unit refrigeration modules including at least a liquid receiver and a refrigerant pump, and the control method includes: When the cooling demand of the terminal system is less than a first preset value, at least one of the multi-unit cooling modules is kept in operation, and shutdown logic is executed to shut down the other multi-unit cooling modules. The shutdown logic includes at least the following: after transferring the refrigerant in the receiver of the multi-unit refrigeration module executing the shutdown logic to the receiver of other multi-unit refrigeration modules that are in operation, the refrigerant pump is turned off.

2. The control method for a multi-unit refrigeration system as described in claim 1, characterized in that, After transferring the refrigerant from the receiver of the multi-unit refrigeration module executing the shutdown logic to the receivers of other multi-unit refrigeration modules in operation, the refrigerant pump is shut down, specifically including: The first refrigerant pump of the multi-unit refrigeration module that executes the shutdown logic is increased to the first preset frequency, and the second refrigerant pump of other multi-unit refrigeration modules that are in operation are operated at the average frequency, wherein the first preset frequency is greater than the average frequency; When the pressure difference between the inlet and outlet of the first fluorine pump is less than or equal to the preset target pressure difference, the first fluorine pump and the second fluorine pump resume their original frequency operation and then the first fluorine pump is shut down.

3. The control method for a multi-unit refrigeration system as described in claim 2, characterized in that, After the first refrigerant pump of the multi-unit refrigeration module executing the shutdown logic is increased to a first preset frequency and the second refrigerant pumps of other multi-unit refrigeration modules in operation are running at an average frequency, the method further includes: When the pressure difference between the inlet and outlet of the first fluorine pump is greater than the preset target pressure difference, the first fluorine pump is increased to a second preset frequency for operation, and the other second fluorine pumps operate at an average frequency, wherein the second preset frequency is greater than the first preset frequency; When the pressure difference between the inlet and outlet of the first fluorine pump is less than or equal to the preset target pressure difference, the first fluorine pump and the second fluorine pump resume their original frequency operation and then the first fluorine pump is shut down.

4. The control method for a multi-unit refrigeration system as described in claim 2, characterized in that, The method includes: when the first fluorine pump is a gear pump, the first preset frequency is set to be 5-15 Hz higher than the average frequency; when the first fluorine pump is a centrifugal pump, the first preset frequency is set to be at least 20 Hz higher than the average frequency.

5. The control method for a multi-unit refrigeration system as described in any one of claims 1-4, characterized in that, Each of the aforementioned multi-unit refrigeration modules further includes at least a compressor, a mechanically cooled solenoid valve, a fan, and a naturally cooled solenoid valve; the method includes: The shutdown logic includes at least the following steps: first, shutting down the compressor and the fan; then, transferring the refrigerant in their receivers to the receivers of other multi-unit refrigeration modules that are in operation; shutting down the refrigerant pump; and finally, shutting down the mechanical cooling solenoid valve and / or the natural cooling solenoid valve.

6. The control method for a multi-unit refrigeration system as described in claim 5, characterized in that, The method further includes: After executing the shutdown logic to shut down the other multi-unit cooling modules, and when only one of the multi-unit cooling modules is in running state, if the cooling demand of the terminal system is less than a second preset value, the running multi-unit cooling module is switched to idle mode.

7. The control method for a multi-unit refrigeration system as described in claim 6, characterized in that, Each of the aforementioned multi-unit refrigeration modules further includes at least a compressor, a mechanical cooling solenoid valve, a fan, a fan coil unit, a natural cooling solenoid valve, and a bypass solenoid valve; The compressor is located in the primary refrigeration circuit of the multi-unit refrigeration module; the mechanical cooling solenoid valve, fan coil unit, natural cooling solenoid valve, bypass solenoid valve, liquid receiver and refrigerant pump are located in the secondary refrigeration circuit of the multi-unit refrigeration module; the fan is used to drive natural cooling air to exchange heat with the fan coil unit; the terminal system is connected in series with the secondary refrigeration circuit. The mechanical cooling solenoid valve, the primary side refrigeration circuit, the liquid receiver, the refrigerant pump, and the terminal system are connected in sequence to form a mechanical refrigeration cycle circuit. The natural cooling solenoid valve, fan coil unit, liquid receiver, refrigerant pump, and terminal system are connected in sequence to form a natural cooling circulation loop; The natural cooling solenoid valve, fan coil unit, primary side refrigeration circuit, liquid receiver, refrigerant pump and terminal system are connected in sequence to form a hybrid refrigeration cycle circuit; The bypass solenoid valve is located between the mechanical cooling solenoid valve and the terminal system, and is used to bypass the primary side refrigeration circuit, the liquid receiver and the refrigerant pump; When the multi-unit refrigeration module is in idle mode, the compressor, the fan, and the natural cooling solenoid valve are all closed, the mechanical cooling solenoid valve and the bypass solenoid valve are open, and the refrigerant pump operates at the lowest frequency.

8. The control method for a multi-unit refrigeration system as described in claim 7, characterized in that, When the multi-unit cooling module is in idle mode, the method further includes: When the cooling demand of the terminal system exceeds a third preset value, the outdoor ambient temperature of the multi-unit refrigeration system is obtained. Based on the outdoor ambient temperature, the multi-unit refrigeration module is switched from the idle state to the refrigeration state.

9. The control method for a multi-unit refrigeration system as described in claim 8, characterized in that, The refrigeration state includes one of the following: natural refrigeration state, mechanical refrigeration state, and hybrid refrigeration state; The natural cooling state is as follows: the compressor, the mechanical cooling solenoid valve and the bypass solenoid valve are closed, the natural cooling solenoid valve is open, and the fan and the refrigerant pump operate at preset frequencies respectively; The mechanical cooling state is as follows: the fan, the natural cooling solenoid valve and the bypass solenoid valve are closed, the mechanical cooling solenoid valve is open, and the compressor and the refrigerant pump operate at preset frequencies respectively; The mixed cooling state is as follows: the mechanical cooling solenoid valve and the bypass solenoid valve are closed, the natural cooling solenoid valve is open, and the compressor, the fan, and the refrigerant pump operate at preset frequencies.

10. A terminal device, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it causes the terminal device to implement the control method as described in any one of claims 1-9.

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