Control method, control apparatus and control device for water chiller unit, and storage medium

Abstract

An operation control method, control apparatus, and control device for a water chiller unit, and a storage medium. The water chiller unit comprises a natural cooling loop and a compressor-based cooling loop which are arranged in parallel. The water chiller unit has a normal mode, a hybrid mode, and an energy saving mode. A water return temperature of the water chiller unit is Tr, an external environmental temperature of the water chiller unit is Te, and ΔT=Tr-Te. The control method comprises the following steps: acquiring ΔT; if ΔT<ΔT1, a selected operation mode being the normal mode; if ΔT1≤ΔT<ΔT2, the selected operation mode being the hybrid mode; and if ΔT≥ΔT2, the selected operation mode being the energy saving mode. In the technical solution of the present application, the water return temperature and the external environmental temperature of the water chiller unit are both incorporated into a determination condition to select the operation mode of the water chiller unit, so that the operation stability of the water chiller unit can be improved.

Description

Control methods, control devices, control equipment and storage media for chiller units

[0001] This application claims priority to Chinese Patent Application No. 202411199788.3, ​​filed on August 29, 2024, entitled "Control Method, Control Device, Control Equipment and Storage Medium for Water Chillers", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of air conditioning technology, and in particular to the operation control method, control device, control equipment and storage medium of chiller units. Background Technology

[0003] In single-fan chiller units, the fan acts as both a condenser fan in the compressor system and a cooling fan in the dry cooler system. These chiller units have multiple operating modes, including natural cooling mode (energy-saving mode) and compressor cooling mode (normal mode). One type of existing chiller unit separates the natural cooling mode and compressor cooling mode, employing two different control logics for each mode. Its advantage is ease of control, but it doesn't fully utilize the unit's energy-saving performance. Another type of chiller unit adds a hybrid mode to the above two modes.

[0004] In the process of developing this application, the inventors discovered at least the following problems in the prior art:

[0005] While adding a hybrid mode to a chiller unit allows it to utilize ambient cooling while simultaneously supplementing cooling capacity through low-frequency compressor operation, achieving maximum energy savings, the shared control logic across all three modes increases the complexity of control. The selection / switching of operating modes for this type of chiller unit typically depends on the external ambient temperature. When significant fluctuations in the ambient temperature necessitate maintaining a stable chiller outlet water temperature, the unit may frequently switch between modes, impacting its operational stability. Summary of the Invention

[0006] This application provides a control method, control equipment, control device, and storage medium for a chiller unit, aiming to improve the operational stability of the chiller unit.

[0007] In a first aspect, embodiments of this application provide a control method for a chiller unit, the chiller unit including a natural refrigeration circuit and a compressor refrigeration circuit arranged in parallel, the chiller unit having a normal mode, a hybrid mode, and an energy-saving mode, the hybrid mode including a first mode; wherein;

[0008] In the normal mode, the compressor refrigeration circuit is open and the natural refrigeration circuit is closed;

[0009] In the first mode of the hybrid mode, both the compressor refrigeration circuit and the natural refrigeration circuit are turned on.

[0010] In the energy-saving mode, the compressor refrigeration circuit is closed and the natural refrigeration circuit is open;

[0011] The actual return water temperature of the chiller unit is T. r The ambient temperature of the chiller unit is T. e △T=T r -T e The control method includes the following steps:

[0012] Obtain △T;

[0013] If △T < △T1, then control the chiller unit to operate in the normal mode;

[0014] If △T1≤△T<△T2, then control the chiller unit to operate in the mixed mode;

[0015] If △T≥△T2, then control the chiller unit to operate in the energy-saving mode.

[0016] In some embodiments, the hybrid mode further includes a second mode in which the compressor refrigeration circuit is turned off and the natural refrigeration circuit is turned on;

[0017] When the chiller unit is operating in the mixed mode, the control method further includes the following steps:

[0018] Determine whether the chiller unit meets the compressor shutdown conditions;

[0019] If the conditions are not met, the chiller unit is controlled to operate in the first mode of the mixed mode;

[0020] If the conditions are met, the chiller unit is controlled to operate in the second mode of the mixed mode.

[0021] In some implementations, determining whether the chiller unit meets the compressor shutdown condition involves: determining whether T is met. r ≤T c T c This refers to the return water temperature at the compressor shutdown point.

[0022] The target return water temperature of the chiller unit is T0, the actual single-run duration of the compressor is t, and the minimum preset single-run duration is τmin. During the switching from the first mode to the second mode, the control method includes the following steps:

[0023] Determine if T is satisfied r ≤Tc +j, 0℃<j<2℃, and whether t≥τmin is satisfied;

[0024] If all conditions are met, then T is to be satisfied. r ≤T c Then, shut down the compressor refrigeration circuit;

[0025] If only T is satisfied r ≤T c If +j, the compressor refrigeration circuit continues to operate, while the natural refrigeration circuit shuts down, until T is satisfied. r If T > T0, reopen the natural cooling circuit and return to the step of determining whether T is satisfied. r ≤T c +j, 0℃<j<2℃, and whether t≥τmin is satisfied, and subsequent steps, until the compressor refrigeration circuit is shut down.

[0026] In some embodiments, the chiller unit further includes a fan for air-cooling the natural refrigeration circuit and the compressor refrigeration circuit.

[0027] In the first mode of the normal mode and the hybrid mode, the operating frequency of the compressor is adjusted according to the cooling capacity demand, and the operating frequency of the fan is adjusted according to the condensing pressure of the compressor's refrigeration circuit.

[0028] In the second mode of the energy-saving mode and the hybrid mode, the operating frequency of the fan is adjusted according to the cooling capacity demand.

[0029] In some implementations, in the second mode of the normal mode, energy-saving mode, and hybrid mode, the upper limit frequency of the fan is A1 and the lower limit frequency is B1.

[0030] In the first mode of the hybrid mode, the upper limit frequency of the fan is A2, the lower limit frequency is B2, and A2 > A1 > B2 > B1.

[0031] In some implementations, the normal mode, the hybrid mode, and the energy-saving mode are switchable, and the control method further includes:

[0032] The switching between the normal mode and the hybrid mode is controlled by determining whether △T≥△T1+i1 is satisfied.

[0033] The switching between the hybrid mode and the energy-saving mode is controlled by determining whether △T≥△T2+i2 is satisfied.

[0034] i1 and i2 are the mode switching hysteresis, where 0 < i1 and i2 < 1.

[0035] In some implementations, the ambient temperature corresponding to △T2 is the ambient temperature that satisfies more than 120% of the rated cooling capacity.

[0036] Secondly, embodiments of this application also propose a control device for a chiller unit. The air-cooled chiller unit includes a natural refrigeration circuit and a compressor refrigeration circuit connected in parallel. The chiller unit has a normal mode, a hybrid mode, and an energy-saving mode. The hybrid mode includes a first mode.

[0037] In the normal mode, the compressor refrigeration circuit is open and the natural refrigeration circuit is closed;

[0038] In the first mode of the hybrid mode, both the compressor refrigeration circuit and the natural refrigeration circuit are turned on.

[0039] In the energy-saving mode, the compressor refrigeration circuit is closed and the natural refrigeration circuit is open;

[0040] The control device includes:

[0041] The acquisition unit is used to acquire ΔT, where ΔT = T. r -T e , among which, T r T represents the actual return water temperature of the chiller unit. e The external ambient temperature where the chiller unit is located;

[0042] The control unit is communicatively connected to the acquisition unit and is used to control the operating mode of the chiller unit according to the value range of ΔT.

[0043] If △T < △T1, then the control unit controls the chiller unit to operate in the normal mode;

[0044] If △T1≤△T<△T2, then the control unit controls the chiller unit to operate in the mixed mode;

[0045] If △T≥△T2, then the control unit controls the chiller unit to operate in the energy-saving mode.

[0046] Thirdly, a chiller unit control device includes a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the control method described in the first aspect.

[0047] Fourthly, embodiments of this application also propose a storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the control method as described in the first aspect.

[0048] Compared with the prior art, this technical solution has at least the following technical advantages:

[0049] This application's technical solution improves the operational stability of the chiller unit by incorporating both the return water temperature and the ambient temperature into the selection criteria for its operating mode. The difference ΔT between the chiller unit's return water temperature and the ambient temperature reflects the cooling capacity of the external environment, i.e., the amount of cooling that the external environment can provide. When ΔT < ΔT1, the cooling capacity provided by the external environment differs significantly from the client's cooling demand, and the chiller unit operates in normal mode. When ΔT ≥ ΔT2, the cooling capacity provided by the external environment alone can meet the client's cooling demand, and the chiller unit operates in energy-saving mode. When ΔT1 ≤ ΔT < ΔT2, the cooling capacity provided by the external environment can at least partially meet the client's cooling demand, and the chiller unit operates in hybrid mode. This application's control method selects the appropriate operating mode for the chiller unit based on the client's cooling demand and the cooling capacity of the external environment, thereby improving the chiller unit's operational stability. If the operating mode of the chiller is selected solely based on the return water temperature or the ambient temperature of the external environment, the actual cooling capacity provided by the chiller may not meet the cooling demand, or the chiller may frequently switch between different operating modes. Attached Figure Description

[0050] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0051] Figure 1 is a flowchart illustrating the control method according to an embodiment of this application;

[0052] Figure 2 is a schematic diagram of the process of switching from the first mode to the second mode in the hybrid mode shown in Figure 1. Detailed Implementation

[0053] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0054] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0055] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0056] This application provides a control method for a chiller unit.

[0057] In this embodiment, the chiller unit includes a natural refrigeration circuit and a compressor refrigeration circuit connected in parallel, and also includes an evaporator and a fan; the natural refrigeration circuit includes a dry cooler, and the compressor refrigeration circuit includes a compressor, a condenser and an electronic expansion valve connected in sequence; both ends of the natural refrigeration circuit and both ends of the compressor refrigeration circuit are connected to the evaporator, and both the natural refrigeration circuit and the compressor refrigeration circuit exchange heat with the client through the evaporator; the fan is used to provide air cooling for the dry cooler and the condenser.

[0058] During operation, when the natural refrigeration circuit is turned on, the refrigerant in the natural refrigeration circuit flows through the dry cooler and exchanges heat with the external environment before flowing into the evaporator. When the compressor refrigeration circuit is turned on, the refrigerant in the compressor refrigeration circuit is compressed into a high-temperature and high-pressure gas by the compressor, then flows through the condenser and exchanges heat with the external environment before entering the evaporator after being throttled by the electronic expansion valve.

[0059] In this embodiment, the chiller unit has a normal mode, a hybrid mode, and an energy-saving mode, wherein the hybrid mode includes a first mode; wherein...

[0060] In normal mode, the compressor refrigeration circuit is open and the natural refrigeration circuit is closed;

[0061] In the first mode of the hybrid mode, both the compressor refrigeration circuit and the natural refrigeration circuit are activated simultaneously.

[0062] In energy-saving mode, the compressor refrigeration circuit is shut down and the natural refrigeration circuit is turned on.

[0063] In this embodiment, the opening and closing of the compressor refrigeration circuit is controlled by controlling the start and stop of the compressor; while there are various ways to control the opening and closing of the natural refrigeration circuit, such as by controlling it with a water pump or valve. The specific control method is related to the design of the natural refrigeration circuit, and those skilled in the art can make corresponding adjustments to the control method according to the actual situation.

[0064] In one embodiment, a two-way valve is also provided in the natural refrigeration circuit, which is formed by connecting the dry cooler and the two-way valve sequentially through pipes. In this embodiment, the opening and closing of the natural refrigeration circuit is controlled by controlling the opening and closing of the two-way valve.

[0065] In the above embodiments, the evaporator is provided with a condensing channel and a water-cooling channel. The two ends of the compressor refrigeration circuit are respectively connected to the two ends of the condensing channel, and the two ends of the natural refrigeration circuit are respectively connected to the two ends of the water-cooling channel. The condenser is located on the air inlet side or air outlet side of the dry cooler. The fan is located on the air outlet side of the condenser and the dry cooler for air-cooling heat dissipation. The chiller unit also includes a water system circulation loop, with both ends connected to the water-cooling channel of the evaporator. The water system circulation loop has an inlet and an outlet, which are respectively connected to the two ends of the liquid-cooling channel of the customer. When the refrigerant in the water system circulation loop flows through the liquid-cooling channel, it exchanges heat with the customer, thereby cooling the customer or regulating the customer's temperature. During operation, when the compressor refrigeration circuit is turned on, the refrigerant in the compressor refrigeration circuit flows into the condensation channel of the evaporator and exchanges heat with the refrigerant in the water cooling channel. Then, the refrigerant in the water cooling channel flows into the liquid cooling channel of the customer and exchanges heat with the customer. When the natural refrigeration circuit is turned on, the refrigerant in the natural refrigeration circuit flows into the water cooling channel of the evaporator and merges with the refrigerant in the water system circulation circuit. Then, it flows into the liquid cooling channel of the customer and exchanges heat with the customer.

[0066] The control method of this application embodiment will be described below using the chiller unit provided in the above embodiment as an example.

[0067] Please refer to Figure 1. In this embodiment of the application, the actual return water temperature of the chiller unit is T. r The ambient temperature of the chiller unit is T. e △T=T r -T e The control method includes the following steps:

[0068] Obtain △T;

[0069] If △T < △T1, then control the chiller unit to operate in normal mode;

[0070] If △T1≤△T<△T2, then control the chiller unit to operate in mixed mode;

[0071] If △T≥△T2, then control the chiller unit to operate in energy-saving mode.

[0072] This application's technical solution improves the operational stability of the chiller unit by incorporating both the return water temperature and the ambient temperature into the selection criteria for its operating mode. The difference ΔT between the chiller unit's return water temperature and the ambient temperature reflects the cooling capacity of the external environment, i.e., the amount of cooling that the external environment can provide. When ΔT < ΔT1, the cooling capacity provided by the external environment differs significantly from the client's cooling demand, and the chiller unit operates in normal mode. When ΔT ≥ ΔT2, the cooling capacity provided by the external environment alone can meet the client's cooling demand, and the chiller unit operates in energy-saving mode. When ΔT1 ≤ ΔT < ΔT2, the cooling capacity provided by the external environment can at least partially meet the client's cooling demand, and the chiller unit operates in hybrid mode. This application's control method selects the appropriate operating mode for the chiller unit based on the client's cooling demand and the cooling capacity of the external environment, thereby improving the chiller unit's operational stability. If the operating mode of the chiller is selected solely based on the return water temperature or the ambient temperature of the external environment, the actual cooling capacity provided by the chiller may not meet the cooling demand, or the chiller may frequently switch between different operating modes.

[0073] In this embodiment, the normal mode, hybrid mode and energy-saving mode can be switched.

[0074] Please refer to Figure 1. In one embodiment, the control method further includes:

[0075] The switching between normal mode and mixed mode is controlled by determining whether △T≥△T1+i1 is satisfied;

[0076] The switching between the hybrid mode and the energy-saving mode is controlled by determining whether △T≥△T2+i2 is satisfied.

[0077] i1 and i2 are the mode switching hysteresis, where 0 < i1 and i2 < 1.

[0078] Specifically, in normal mode, when the external ambient temperature T e As the temperature gradually decreases, ΔT will gradually increase. When ΔT increases to ΔT≥ΔT1+i1, the operating mode of the chiller unit will be switched from normal mode to mixed mode.

[0079] In hybrid mode, when the external ambient temperature T e As the temperature gradually decreases, ΔT will gradually increase. When ΔT increases to ΔT≥ΔT2+i2, the operating mode of the chiller unit will be switched from hybrid mode to energy-saving mode.

[0080] In energy-saving mode, when the external ambient temperature T eAs the temperature rises, ΔT will gradually decrease. When ΔT decreases to ΔT < ΔT² + i², the chiller unit's operating mode will be switched from energy-saving mode to hybrid mode.

[0081] In hybrid mode, when the external ambient temperature T e As the temperature gradually increases, ΔT will gradually decrease. When ΔT decreases to ΔT < ΔT1 + i1, the operating mode of the chiller unit will be switched from mixed mode to normal mode.

[0082] Please refer to Figure 1. In one embodiment, the hybrid mode further includes a second mode in which the compressor refrigeration circuit is turned off and the natural refrigeration circuit is turned on.

[0083] When the chiller unit is operating in mixed mode, the control method also includes the following steps:

[0084] Determine whether the chiller unit meets the compressor shutdown conditions;

[0085] If the conditions are not met, the chiller unit will be controlled to operate in the first mode of the mixed mode;

[0086] If the conditions are met, the chiller unit will be controlled to operate in the second mode of the mixed mode.

[0087] In the above embodiments, only the natural cooling circuit is open in both the second mode of the hybrid mode and the energy-saving mode. The switching between the second mode of the hybrid mode and the energy-saving mode does not involve changes in the state of the unit's components. This setting can raise the compressor's start-up point in the energy-saving mode, avoiding the need for the compressor to intervene when the chiller unit just starts running at a high water temperature, thus preventing increased power consumption of the chiller unit.

[0088] In the above embodiments, in the first mode of normal mode and hybrid mode, the operating frequency of the compressor is adjusted according to the cooling capacity demand, and the operating frequency of the fan is adjusted according to the condensing pressure of the compressor refrigeration circuit.

[0089] In the second mode, which combines energy-saving and hybrid modes, the fan's operating frequency is adjusted according to the cooling capacity demand.

[0090] In the above embodiments, in the second mode of normal mode, energy-saving mode and hybrid mode, the upper limit frequency of the fan is A1 and the lower limit frequency is B1.

[0091] In the first mode of the hybrid mode, the upper limit frequency of the wind turbine is A2, the lower limit frequency is B2, and A2 > A1 > B2 > B1.

[0092] Based on the above embodiments, in one embodiment, the ambient temperature corresponding to △T2 is the ambient temperature that satisfies more than 120% of the rated cooling capacity.

[0093] In the above embodiment, determining whether the chiller unit meets the compressor shutdown condition is as follows: determining whether T is met. r ≤T c T c This refers to the return water temperature at the compressor shutdown point.

[0094] In the above embodiments, in the first mode of the hybrid mode, when the client's heat load is constant and the external ambient temperature gradually decreases, the compressor will reduce its frequency and the fan will reduce its speed (compared to the same compressor frequency in normal mode, the cooling capacity of the chiller in hybrid mode will be slightly lower than that in normal mode due to the reduced fan speed), and the cooling capacity output by both the natural refrigeration circuit and the compressor refrigeration circuit will be further reduced; when the external ambient temperature drops below the switching point (at which the actual return water temperature drops to the compressor shutdown point return water temperature, and this switching point varies with the client's heat load), the compressor frequency and fan speed remain at the lower limit, the cooling capacity output by the chiller exceeds the client's cooling capacity demand, the return water temperature of the chiller reaches the compressor shutdown point, the compressor shuts down, and the dry cooler works alone (the natural refrigeration circuit cools alone), but at this time the dry cooler working alone cannot meet the client's cooling capacity demand, the return water temperature of the chiller will rise, and when the return water temperature rises to the compressor start-up demand point, the compressor will start again. At this time, the external ambient temperature remains unchanged, which will cause the compressor to start and stop frequently, and the outlet water temperature of the chiller will fluctuate greatly.

[0095] Referring to Figure 2, to further address the technical problems of frequent compressor start-stop and unstable chiller outlet water temperature in the hybrid mode, in one embodiment, the target return water temperature of the chiller is T0, the actual single-run duration of the compressor is t, and the minimum preset single-run duration is τmin. During the switching from the first mode to the second mode of the hybrid mode, the control method includes the following steps:

[0096] Determine if T is satisfied r ≤T c +j, 0℃<j<2℃, and whether t≥τmin is satisfied;

[0097] If all conditions are met, then T is to be satisfied. r ≤T c Then, shut down the compressor refrigeration circuit;

[0098] If only T is satisfied r ≤T c If +j, the compressor refrigeration circuit continues to operate, while the natural refrigeration circuit shuts down, until T is satisfied. r If T > T0, reopen the natural cooling circuit and return to the step of determining whether T is satisfied. r ≤T c+j, 0℃<j<2℃, and whether t≥τmin is satisfied, and subsequent steps, until the compressor refrigeration circuit is shut down.

[0099] Secondly, this application also proposes a control device for a chiller unit.

[0100] In this embodiment, the specific structure of the chiller unit is as described in the above embodiments, and will not be repeated here.

[0101] In this embodiment of the application, the control device includes:

[0102] The acquisition unit is used to acquire ΔT, where ΔT = T. r -T e , among which, T r T represents the actual return water temperature of the chiller unit. e The ambient temperature of the chiller unit.

[0103] The control unit, which is communicatively connected to the acquisition unit, is used to control the operating mode of the chiller unit according to ΔT.

[0104] If △T < △T1, then the control unit controls the chiller unit to operate in normal mode;

[0105] If △T1≤△T<△T2, then the control unit controls the chiller unit to operate in mixed mode;

[0106] If △T≥△T2, then the control unit controls the chiller unit to operate in energy-saving mode.

[0107] Thirdly, this application also proposes a control device for a chiller unit.

[0108] In this embodiment of the application, the control device includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the steps of the control method as described in the first aspect.

[0109] Fourthly, this application also proposes a storage medium.

[0110] In this embodiment of the application, the storage medium stores a computer program, which, when executed by a processor, causes the processor to perform the steps of the control method as described in the first aspect.

[0111] It should be noted that the control methods, devices, equipment and storage media of the above-mentioned chiller units belong to a general inventive concept, and the contents of the embodiments of the control methods, devices, equipment and storage media of the chiller units are applicable to each other.

[0112] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0113] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control method for a chiller unit, characterized in that, The chiller unit includes a natural refrigeration circuit and a compressor refrigeration circuit connected in parallel. The chiller unit has a normal mode, a hybrid mode, and an energy-saving mode. The hybrid mode includes a first mode. In the normal mode, the compressor refrigeration circuit is open and the natural refrigeration circuit is closed; In the first mode of the hybrid mode, both the compressor refrigeration circuit and the natural refrigeration circuit are turned on. In the energy-saving mode, the compressor refrigeration circuit is closed and the natural refrigeration circuit is open; The actual return water temperature of the chiller unit is T. r The ambient temperature of the chiller unit is T. e △T=T r -T e The control method includes the following steps: Obtain △T; If △T < △T1, then control the chiller unit to operate in the normal mode; If △T1≤△T<△T2, then control the chiller unit to operate in the mixed mode; If △T≥△T2, then control the chiller unit to operate in the energy-saving mode.

2. The control method as described in claim 1, characterized in that, The hybrid mode also includes a second mode, in which the compressor refrigeration circuit is turned off and the natural refrigeration circuit is turned on; When the chiller unit is operating in the mixed mode, the control method further includes the following steps: Determine whether the chiller unit meets the compressor shutdown conditions; If the conditions are not met, the chiller unit is controlled to operate in the first mode; If the conditions are met, the chiller unit is controlled to operate in the second mode.

3. The control method as described in claim 2, characterized in that, The determination of whether the chiller unit meets the compressor shutdown condition is as follows: Determine whether T is met. r ≤T c T c This refers to the return water temperature at the compressor shutdown point. The target return water temperature of the chiller unit is T0, the actual single-run duration of the compressor is t, and the minimum preset single-run duration is τmin. During the switching from the first mode to the second mode, the control method includes the following steps: Determine if T is satisfied r ≤T c +j, 0℃<j<2℃, and whether t≥τmin is satisfied; If all conditions are met, then T is to be satisfied. r ≤T c Then, shut down the compressor refrigeration circuit; If only T is satisfied r ≤T c If +j, the compressor refrigeration circuit continues to operate, while the natural refrigeration circuit shuts down, until T is satisfied. r If T > T0, reopen the natural cooling circuit and return to the step of determining whether T is satisfied. r ≤T c +j, 0℃<j<2℃, and whether t≥τmin is satisfied, and subsequent steps, until the compressor refrigeration circuit is shut down.

4. The control method as described in claim 2, characterized in that, The chiller unit also includes a fan for air-cooling the natural refrigeration circuit and the compressor refrigeration circuit. In the first mode of the normal mode and the hybrid mode, the operating frequency of the compressor is adjusted according to the cooling capacity demand, and the operating frequency of the fan is adjusted according to the condensing pressure of the compressor's refrigeration circuit. In the second mode of the energy-saving mode and the hybrid mode, the operating frequency of the fan is adjusted according to the cooling capacity demand.

5. The control method as described in claim 4, characterized in that, In the normal mode, energy-saving mode, and the second mode of the hybrid mode, the upper limit frequency of the fan is A1, and the lower limit frequency is B1. In the first mode of the hybrid mode, the upper limit frequency of the fan is A2, the lower limit frequency is B2, and A2 > A1 > B2 > B1.

6. The control method as described in claim 1, characterized in that, The control method can switch between the normal mode, the hybrid mode, and the energy-saving mode, and further includes: The switching between the normal mode and the hybrid mode is controlled by determining whether △T≥△T1+i1 is satisfied. The switching between the hybrid mode and the energy-saving mode is controlled by determining whether △T≥△T2+i2 is satisfied. i1 and i2 are the mode switching hysteresis, where 0 < i1 and i2 < 1.

7. The control method as described in claim 1, characterized in that, The ambient temperature corresponding to △T2 is the ambient temperature that meets more than 120% of the rated cooling capacity.

8. A control device for a chiller unit, characterized in that, The chiller unit includes a natural refrigeration circuit and a compressor refrigeration circuit connected in parallel. The chiller unit has a normal mode, a hybrid mode, and an energy-saving mode. The hybrid mode includes a first mode. In the normal mode, the compressor refrigeration circuit is open and the natural refrigeration circuit is closed; In the first mode of the hybrid mode, both the compressor refrigeration circuit and the natural refrigeration circuit are turned on. In the energy-saving mode, the compressor refrigeration circuit is closed and the natural refrigeration circuit is open; The control device includes: The acquisition unit is used to acquire ΔT, where ΔT = T. r -T e , among which, T r T represents the actual return water temperature of the chiller unit. e The external ambient temperature where the chiller unit is located; The control unit is communicatively connected to the acquisition unit and is used to control the operating mode of the chiller unit according to ΔT. If △T < △T1, then the control unit controls the chiller unit to operate in the normal mode; If △T1≤△T<△T2, then the control unit controls the chiller unit to operate in the mixed mode; If △T≥△T2, then the control unit controls the chiller unit to operate in the energy-saving mode.

9. A chiller unit control device, comprising a memory and a processor, characterized in that, The memory stores a computer program that, when executed by the processor, causes the processor to perform the steps of the control method as described in any one of claims 1 to 7.

10. A storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it causes the processor to perform the steps of the control method as described in any one of claims 1 to 7.

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