Dual cold source air conditioning unit and control method

Abstract

The application discloses a double-cold-source air conditioning unit and a control method. The air conditioning unit comprises a natural cooling system, a refrigerated water circulation loop, and a cooling coil arranged on the refrigerated water circulation loop. Along the flow path of the refrigerated water in the refrigerated water circulation loop, a first bypass channel and a second bypass channel are arranged on the refrigerated water circulation loop in sequence, and the first bypass channel is connected in parallel with the cooling coil. A compressor refrigeration system comprises a compressor, an evaporator, and a condenser, which are connected to form a refrigerant circulation loop. A temperature detection system comprises a plurality of temperature sensors for detecting the supply air temperature of the air conditioning unit, detecting the inlet and outlet water temperatures of the cooling coil, and detecting the return air temperature of the air conditioning unit. The refrigerated water in the second bypass channel exchanges heat with the refrigerant in the condenser to remove the heat of the refrigerant. The application solves the problems of low switching efficiency caused by manual switching and the inability to smoothly and automatically switch between multiple working modes.

Description

Technical Field

[0001] This application relates to the field of computer room air conditioning technology, and in particular to a dual-source air conditioning unit and its control method. Background Technology

[0002] Dual-source air conditioning systems typically employ a parallel connection of liquid cooling and air cooling systems. Both systems can independently provide sufficient cooling capacity to the data center, ensuring the reliability of the dual-source air conditioning system.

[0003] In the process of realizing this invention, the inventors discovered that the prior art has at least the following problems:

[0004] Currently, dual-source air conditioners have multiple operating modes depending on outdoor conditions and cooling needs. However, these modes cannot be automatically switched, usually requiring manual switching, which is inefficient and affects the reliability of the computer room. Furthermore, manual switching does not follow the principle of smooth transition between multiple operating modes, which can easily lead to sudden drops or rises in temperature within the computer room, affecting the safe operation of equipment and reducing its lifespan.

[0005] Therefore, in view of the above-mentioned technical problems, how to achieve smooth and automatic switching between multiple working modes is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this application is to provide a dual-source air conditioning unit and control method, which solves the problems of low switching efficiency and inability to smoothly and automatically switch between multiple working modes caused by manual switching.

[0007] To achieve the above objectives, this application provides a dual-source air conditioning unit, comprising:

[0008] The natural cooling system includes a chilled water circulation loop and a surface cooler coil disposed on the chilled water circulation loop. Along the flow path of chilled water in the chilled water circulation loop, a first bypass channel and a second bypass channel are sequentially provided on the chilled water circulation loop. The first bypass channel is connected in parallel with the surface cooler coil.

[0009] A compressor refrigeration system includes a compressor, an evaporator, and a condenser, which are connected to form a refrigerant circulation loop;

[0010] The temperature detection system includes several temperature sensors, which are used to detect the supply air temperature of the air conditioning unit, the inlet and outlet water temperatures of the surface cooler coil, and the return air temperature of the air conditioning unit.

[0011] In this process, the chilled water in the second bypass channel exchanges heat with the refrigerant in the condenser to remove the heat from the refrigerant.

[0012] Preferably, the condenser is a condenser plate heat exchanger, the condenser plate heat exchanger has a first passage communicating with the bypass passage, and the condenser plate heat exchanger also has a second passage communicating with the refrigerant circulation loop, the first passage and the second passage are set independently.

[0013] Preferably, the evaporator is an evaporator coil, and the evaporator coil has a third passage connected to the refrigerant circulation loop. The evaporator coil and the surface cooler coil are positioned corresponding to each other and connected in series in the airflow direction, so that the return air from the computer room passes through the surface cooler coil and the evaporator coil before being sent into the computer room.

[0014] Preferably, the compressor refrigeration system consists of two sets, with the two sets sharing one condenser heat exchanger and one evaporator coil. The condenser heat exchanger has two second passages, which are independently configured. The evaporator heat exchanger also has two third passages, which are intersecting and independently configured.

[0015] A control method, applied to the aforementioned dual-source air conditioning unit, includes:

[0016] Determine the current operating mode of the air conditioning unit, including: compressor cooling mode, pre-cooling mode, and natural cooling mode;

[0017] When the compressor is running in cooling mode, if the inlet water temperature of the surface cooler coil is less than or equal to the return air temperature of the computer room and continues for a preset time, the system will automatically switch to running the pre-cooling mode.

[0018] When the pre-cooling mode is running, if the inlet water temperature is less than or equal to the preset air supply temperature of the computer room, and the compressor runs at the minimum frequency for a preset time, then the system will automatically switch to the natural cooling mode; or, if the actual air supply temperature of the computer room is less than the preset air supply temperature, and the compressor runs at the minimum frequency for a preset time, then the system will automatically switch to the natural cooling mode.

[0019] When the precooling mode is running, if the inlet water temperature is greater than the return air temperature and this continues for a preset time, the system will automatically switch to the compressor cooling mode.

[0020] When the natural cooling mode is running, if the flow rate in the chilled water circulation loop is greater than or equal to the preset flow rate, and the actual air supply temperature is greater than the preset air supply temperature for a preset time, the system will automatically switch to the pre-cooling mode; or, if the inlet water temperature is greater than or equal to the preset air supply temperature for a preset time, the system will automatically switch to the pre-cooling mode.

[0021] Preferably, the step of determining the current operating mode of the air conditioning unit includes:

[0022] When the air conditioning unit starts, if the inlet water temperature is greater than or equal to the preset return air temperature, it starts in the compressor cooling mode, and the current operating mode is the compressor cooling mode; if the preset supply air temperature is less than the inlet water temperature and less than the preset return air temperature, it starts in the pre-cooling mode, and the current operating mode is the pre-cooling mode; if the inlet water temperature is less than or equal to the preset supply air temperature, it starts in the natural cooling mode, and the current operating mode is the natural cooling mode.

[0023] Preferably, the step of determining the current operating mode of the air conditioning unit further includes:

[0024] During the operation of the air conditioning unit, the current operating mode of the air conditioning unit is determined based on the current status of the surface cooler coil, the first bypass channel, the second bypass channel, the chilled water circulation loop, and the compressor.

[0025] If the second bypass channel is open, the chilled water circulation loop corresponding to the second bypass channel is closed, the first bypass channel is open, the surface cooler coil is closed, and the compressor is running, then the operating mode is determined to be the compressor refrigeration mode;

[0026] If the second bypass channel is open, the chilled water circulation loop corresponding to the second bypass channel is closed, the first bypass channel is closed, the surface cooler coil is turned on, and the compressor is running, then the operating mode is determined to be the pre-cooling mode;

[0027] If the second bypass channel is turned off, the chilled water circulation loop corresponding to the second bypass channel is turned on, the first bypass channel is turned off, the surface cooler coil is turned on, and the compressor is turned off, then the operating mode is determined to be the natural cooling mode.

[0028] Preferably, the step of automatically switching from the compressor cooling mode to the pre-cooling mode includes:

[0029] The first bypass channel is gradually shut off, while the surface cooler coil is gradually turned on. The second bypass channel remains shut off, and the chilled water circulation loop connected in parallel with the second bypass channel remains shut off. The compressor continues to run in the pre-cooling mode. In the pre-cooling mode, the compressor adjusts its frequency according to the cooling demand of the computer room, and the flow rate in the second bypass channel is adjusted according to the temperature difference between the inlet and outlet water of the surface cooler coil.

[0030] Preferably, the step of automatically switching from the pre-cooling mode to the natural cooling mode includes:

[0031] The first bypass channel is kept off, the surface cooler coil is kept on, the compressor is shut down, and after the compressor is shut down, the chilled water circulation loop corresponding to the second bypass channel is delayed in operation. The second bypass channel is shut down after the compressor is shut down and delayed in operation to run the natural cooling mode. When running the natural cooling mode, the flow rate in the chilled water circulation loop is adjusted according to the actual air supply temperature.

[0032] Preferably, the step of automatically switching from the pre-cooling mode to the compressor cooling mode includes:

[0033] The system controls the surface cooler coil to gradually close, while simultaneously controlling the first bypass channel to gradually open. The system controls the chilled water circulation loop corresponding to the second bypass channel to remain closed, controls the second bypass channel to remain open, and controls the compressor to remain running in the compressor cooling mode. When running the compressor cooling mode, the compressor adjusts its frequency according to the cooling capacity requirements of the computer room, and the flow rate in the second bypass channel is adjusted according to the temperature difference between the inlet and outlet water of the surface cooler coil.

[0034] Preferably, the step of automatically switching from running the natural cooling mode to running the pre-cooling mode includes:

[0035] The chilled water circulation loop corresponding to the second bypass channel is shut off, while the second bypass channel remains open. During the shutdown of the chilled water circulation loop, the flow rate in the second bypass channel is adjusted based on the current flow rate of the chilled water circulation loop and the inlet and outlet water temperature difference of the surface cooler coil. After the second bypass channel is turned on, the compressor is controlled to run for a delay, the surface cooler coil remains open, and the first bypass channel remains closed to operate the pre-cooling mode. During the operation of the pre-cooling mode, the compressor adjusts its frequency according to the cooling capacity requirements of the computer room, and the flow rate in the second bypass channel is adjusted according to the inlet and outlet water temperature difference.

[0036] Compared with the prior art, the technical solution provided in this application has at least the following beneficial effects:

[0037] The air conditioning unit of this application can adjust its operating mode by changing the status of the first bypass channel, the second bypass channel, the surface cooler coil, the chilled water circulation loop, and the compressor. The operating modes include compressor cooling mode, pre-cooling mode, and natural cooling mode. In compressor cooling mode, the compressor cooling system alone provides cooling capacity, with chilled water exchanging heat with the refrigerant. In pre-cooling mode, both the compressor cooling system and the natural cooling system are used to provide cooling capacity, with chilled water exchanging heat with the refrigerant. In natural cooling mode, the natural cooling system alone provides cooling capacity, with chilled water not exchanging heat with the refrigerant. Based on the above, this application achieves automatic switching between compressor cooling mode and pre-cooling mode, automatic switching between pre-cooling mode and natural cooling mode, and thus automatic switching between various modes.

[0038] Meanwhile, when the air conditioning unit of this application switches modes, it also follows the switching principle of compressor cooling mode to pre-cooling mode, pre-cooling mode to natural cooling mode, natural cooling mode to pre-cooling mode, and pre-cooling mode to compressor cooling mode, so as to avoid direct switching such as natural cooling mode to compressor cooling mode and prevent the problem of sudden rise and fall of temperature in the machine room. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, 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 embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of a dual-cooling-source air conditioning unit provided in an embodiment of this application;

[0041] Figure 2 This is another schematic diagram of the dual-cooling-source air conditioning unit provided in the embodiments of this application.

[0042] In the diagram: 1- Chilled water circulation loop; 2- Cooler coil; 3- Three-way valve; 4- First bypass channel; 5- Main control valve; 6- Bypass valve; 7- Second bypass channel; 8- Refrigerant circulation loop; 9- Condenser; 10- Compressor; 11- Expansion valve; 12- Evaporator; 13- Temperature sensor. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] It should be noted that in this embodiment, the orientation or positional relationship indicated by terms such as "upper," "lower," "front," and "rear" is based on the orientation or positional relationship shown in the accompanying drawings. It is used only for the convenience of describing this application and for simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Please refer to Figure 1 In this embodiment, a dual-source air conditioning unit is provided. The air conditioning unit includes a compressor refrigeration system, a natural cooling system, and a temperature detection system. The natural cooling system includes a chilled water circulation loop 1 and a surface cooler coil 2 installed on the chilled water circulation loop 1. The chilled water circulation loop 1 is connected to an external cooling unit, such as a cooling tower, which can cool the chilled water by exchanging heat with the outdoor environment. The cooled chilled water exchanges heat with the return air of the machine room at the surface cooler coil 2.

[0047] Along the flow path of chilled water in the chilled water circulation loop 1, a first bypass channel 4 and a second bypass channel 7 are sequentially provided on the chilled water circulation loop 1. That is to say, when chilled water flows along the chilled water circulation loop 1, it first reaches the position of the first bypass channel 4 and then reaches the position of the second bypass channel 7. The first bypass channel 4 is connected in parallel with the surface cooler coil 2, so that the chilled water can flow through the surface cooler coil 2 or the first bypass channel 4 according to the state of the first bypass channel 4 and the surface cooler coil 2.

[0048] Similarly, the flow of chilled water through the second bypass channel 7 or the corresponding parallel chilled water circulation loop 1 can be determined based on the state of the second bypass channel 7 and the chilled water circulation loop 1 connected in parallel with the second bypass channel 7.

[0049] In some embodiments, a three-way valve 3 and a main control valve 5 can be installed on the chilled water circulation loop 1 at the liquid outlet end of the surface cooler coil 2. The first end of the three-way valve 3 is connected to the liquid outlet end of the surface cooler coil 2, the second end of the three-way valve 3 is connected to the main control valve 5, and the third end of the three-way valve 3 is connected to the chilled water circulation loop 1 at the liquid inlet end of the surface cooler coil 2 through a first bypass channel 4. It is understood that the three-way valve 3 has three ports, two of which remain open and the other port remains closed.

[0050] The main control valve 5 is located on the chilled water circulation loop 1, which is connected in parallel with the second bypass channel 7. That is, the second bypass channel 7 is connected in parallel with the main control valve 5, and a bypass valve 6 is provided on the second bypass channel 7.

[0051] Based on the above embodiments, the flow path of chilled water can be changed by altering the state of the three-way valve 3. For example, when the first and second ends of the three-way valve 3 are open, the surface cooler is in the open state, and chilled water can pass through the surface cooler coil 2. When the second and third ends of the three-way valve 3 are open, since the first end of the three-way valve 3 is closed, the chilled water does not pass through the surface cooler coil 2, and the surface cooler coil 2 is in the closed state. The chilled water flows directly from the first bypass channel 4 to the three-way valve 3, and from the third end of the three-way valve 3 to the second end, and finally flows towards the main control valve 5. Similarly, by changing the states of the main control valve 5 and the bypass valve 6, the flow path of chilled water in the chilled water circulation loop 1 and the second bypass channel 7 can also be changed, which will not be elaborated here.

[0052] A compressor refrigeration system refers to a system where the refrigerant, fluorine, is converted into a high-pressure, high-temperature gas from the outlet of compressor 10 and enters condenser 9. Heat is released in condenser 9, and the gas then passes through expansion valve 11 for throttling and pressure reduction before entering evaporator 12 to exchange heat with the return air from the machine room. Finally, it re-enters compressor 10 to form a cycle. Specifically, the compressor refrigeration system includes compressor 10, evaporator 12, and condenser 9, which are connected to form a refrigerant circulation loop 8. The compressor refrigeration system also includes components such as expansion valve 11, suction pressure detector, suction temperature detector, condensing pressure detector, and condensing temperature detector, which can be referenced in existing technologies.

[0053] When chilled water flows through the second bypass channel 7, the chilled water in the second bypass channel 7 can also exchange heat with the refrigerant in the condenser 9, thereby removing the heat from the refrigerant. Specifically, the air conditioning unit of this application can be divided into compressor refrigeration mode, pre-cooling mode, and natural cooling mode according to the utilization of natural cold source. In compressor refrigeration mode, the cooling capacity generated by the compressor refrigeration system is used to exchange heat with the return air of the machine room. At the same time, after the refrigerant enters the condenser 9, it exchanges heat with the chilled water flowing through the condenser 9 and releases heat to reduce the condensing pressure of the condenser 9 and improve the refrigeration efficiency of the compressor refrigeration system. In pre-cooling mode, the cooling capacity generated by the compressor refrigeration system and the natural cooling system is used to exchange heat with the return air of the machine room. The chilled water can pass through the surface cooler coil 2. At the same time, after the chilled water exchanges heat with the return air of the machine room at the surface cooler coil 2, it will also flow through the condenser 9, thereby exchanging heat with the refrigerant in the condenser 9 and removing heat.

[0054] The natural cooling mode utilizes a natural cooling system, where chilled water only exchanges heat with the return air of the machine room through the surface cooler coil 2, and then flows back to the cooling unit to form a cycle.

[0055] The temperature detection system includes several temperature sensors 13, which can be installed on the supply air side of the air conditioning unit, the water inlet side of the cooling coil 2, and the return air side of the air conditioning unit, respectively, to detect the supply air temperature, the water inlet temperature of the cooling coil 2, and the return air temperature of the air conditioning unit. Alternatively, pressure sensors can be installed on the water inlet and outlet sides of the cooling coil 2 to detect the pressure difference between the inlet and outlet water of the cooling coil 2, depending on the actual situation.

[0056] In the compressor refrigeration system, the condenser 9 can be a condenser plate heat exchanger. The condenser plate heat exchanger has a second passage connected to the second bypass passage 7. The condenser plate heat exchanger also has a first passage connected to the refrigerant circulation loop 8. The first passage and the second passage are set independently. When the air conditioning unit is in compressor refrigeration mode or pre-cooling mode, chilled water can enter the second passage through the bypass passage. At the same time, the refrigerant can enter the first passage through the refrigerant circulation loop 8, so that the chilled water and the refrigerant exchange heat at the condenser plate heat exchanger to cool the refrigerant.

[0057] The corresponding evaporator 12 can be an evaporator coil, which has a third passage connected to the refrigerant circulation loop 8, so that the refrigerant exchanges heat with the return air of the machine room in the evaporator coil. The evaporator coil and the surface cooler coil 2 are positioned correspondingly and connected in series in the airflow direction, so that the return air of the machine room is sent into the machine room after passing through the surface cooler coil 2 and the evaporator coil.

[0058] In some embodiments, the surface cooler coil 2 and the evaporator coil are arranged sequentially in the airflow direction, that is, the surface cooler coil 2 serves as the return air side coil, while the evaporator coil serves as the supply air side coil; therefore, when the air conditioning unit is running in compressor cooling mode and pre-cooling mode, the supply air temperature is controlled by the evaporator coil, and when running in natural cooling mode, the supply air temperature is controlled by the surface cooler coil 2.

[0059] Please refer to Figure 2 The aforementioned compressor refrigeration system can consist of two sets, sharing a single condenser heat exchanger and an evaporator coil. Each compressor refrigeration system operates on a similar principle. The condenser heat exchanger has two first-passage channels, each corresponding to one of the two refrigerant circulation loops, and these two channels are independently configured. The evaporator heat exchanger also has two third-passage channels, each corresponding to one of the two refrigerant circulation loops, and these two third-passage channels are intersecting yet independently configured. This shared condenser heat exchanger and evaporator coil configuration reduces the additional machine room space required by the two compressor refrigeration systems while simultaneously improving heat exchange efficiency.

[0060] In this embodiment, a control method is also provided, which can be applied to the above-mentioned dual-source air conditioning unit. The specific steps are as follows:

[0061] Determine the current operating mode of the air conditioning unit. Operating modes include: compressor cooling mode, pre-cooling mode, and natural cooling mode.

[0062] When the compressor is running in cooling mode, if the inlet water temperature of the surface cooler coil 2 is less than or equal to the return air temperature of the computer room, it means that the surface cooler coil 2 and the return air of the computer room have a certain heat exchange effect. The surface cooler coil 2 can provide a certain amount of cooling capacity. Therefore, after a preset time of stable operation (60s-600s), it can automatically switch to the pre-cooling mode to provide a certain amount of cooling capacity using the natural cooling system, thereby reducing the operating frequency of the compressor 10 and reducing power consumption.

[0063] When operating in pre-cooling mode, if the inlet water temperature of the surface cooler coil 2 is less than or equal to the preset air supply temperature of the computer room, and the compressor 10 operates at its minimum frequency for a preset time (60s-600s), it indicates that the cooling capacity provided by the compressor refrigeration system is relatively small. The cooling capacity provided by the surface cooler coil 2 can meet the air supply temperature of the computer room. Therefore, it can automatically switch to natural cooling mode, with the natural cooling system providing the cooling capacity alone. Alternatively, when operating in pre-cooling mode, if the actual air supply temperature of the computer room is less than the preset air supply temperature, and the compressor 10 operates at its minimum frequency for a preset time (0s-900s), it indicates that even with the compressor refrigeration system providing relatively small cooling capacity, the cooling capacity provided by the surface cooler coil 2 can still meet the air supply temperature requirements of the computer room. Therefore, it can also automatically switch to natural cooling mode, with the natural cooling system providing the cooling capacity alone.

[0064] In addition, when running the precooling mode, if the inlet water temperature of the surface cooler coil 2 is greater than the return air temperature and continues for a preset time (60s-600s), it means that the natural cooling system does not have the ability to provide cooling capacity at this time. Therefore, it can automatically switch to the compressor cooling mode, and the compressor cooling system can provide cooling capacity alone.

[0065] When operating in natural cooling mode, if the flow rate in chilled water circulation loop 1 is greater than or equal to the preset flow rate, and the actual supply air temperature is greater than the preset supply air temperature, and this condition persists for a preset time (30s-300s), it indicates that the cooling capacity provided by the natural cooling system in full-power operation mode is still insufficient to meet the cooling demand of the computer room. Therefore, it can automatically switch to pre-cooling mode, where the natural cooling system and the compressor refrigeration system provide cooling capacity simultaneously. Alternatively, when operating in natural cooling mode, if the inlet water temperature of the surface cooler coil 2 is greater than or equal to the preset supply air temperature, and this condition persists for a preset time (0s-600s), it indicates that the surface cooler coil 2 may still have the capacity to provide cooling capacity, but the provided cooling capacity is insufficient to meet the requirements of the preset supply air temperature. Therefore, it needs to automatically switch to pre-cooling mode, where the natural cooling system and the compressor refrigeration system provide cooling capacity simultaneously.

[0066] The air conditioning unit of this application can adjust its operating mode by changing the status of the first bypass channel 4, the second bypass channel 7, the surface cooler coil 2, the chilled water circulation loop 1, and the compressor 10. The operating modes include compressor cooling mode, pre-cooling mode, and natural cooling mode. In compressor cooling mode, the compressor cooling system alone provides cooling capacity, with chilled water exchanging heat with the refrigerant. In pre-cooling mode, both the compressor cooling system and the natural cooling system are used to provide cooling capacity, with chilled water exchanging heat with the refrigerant. In natural cooling mode, the natural cooling system alone provides cooling capacity, with chilled water not exchanging heat with the refrigerant. Based on the above, this application achieves automatic switching between compressor cooling mode and pre-cooling mode, and between pre-cooling mode and natural cooling mode, thereby achieving automatic switching between various modes. Furthermore, when switching modes, the air conditioning unit of this application follows the switching principles from compressor cooling mode to pre-cooling mode, from pre-cooling mode to natural cooling mode, from natural cooling mode to pre-cooling mode, and from pre-cooling mode to compressor cooling mode, avoiding direct switching such as from natural cooling mode to compressor cooling mode, and preventing sudden temperature rises and falls in the machine room.

[0067] It should be noted that determining the current operating mode of the air conditioning unit includes determining the operating mode when the air conditioning unit is started, and determining the operating mode during operation; specifically, the steps for determining the operating mode when the air conditioning unit is started include:

[0068] When the air conditioning unit starts, if the inlet water temperature of the surface cooler coil 2 is greater than or equal to the preset return air temperature, it means that the natural cooling system does not have the ability to provide cooling capacity. Therefore, the compressor refrigeration system provides cooling capacity separately, and the corresponding operation mode should be compressor refrigeration mode. At this time, the current operating mode is compressor refrigeration mode.

[0069] If the preset supply air temperature is less than the inlet water temperature of the surface cooler coil 2 and less than the preset return air temperature, it means that the natural cooling system has the ability to exchange heat with the return air of the computer room and can provide a certain amount of cooling capacity. However, since the inlet water temperature of the surface cooler coil 2 is greater than the preset supply air temperature, the cooling capacity provided by the natural cooling system cannot meet the supply air temperature requirements of the computer room. Therefore, the natural cooling system and the compressor refrigeration system need to provide cooling capacity at the same time and start in pre-cooling mode. At this time, the current operating mode is pre-cooling mode.

[0070] If the inlet water temperature of the surface cooler coil 2 is less than or equal to the preset air supply temperature, it means that the cooling capacity provided by the natural cooling system can meet the cooling capacity requirements of the computer room. At this time, the natural cooling system can provide cooling capacity independently and start in natural cooling mode. The current operating mode is natural cooling mode.

[0071] The steps for determining the operating mode of the air conditioning unit during operation include:

[0072] During the operation of the air conditioning unit, the return air temperature, supply air temperature, and inlet water temperature of the surface cooler coil 2 will change according to different operating conditions. Therefore, it is difficult and inaccurate to determine the operating mode using the above conditions. Therefore, the current operating mode of the air conditioning unit can be determined based on the current status of the first bypass channel 4, the second bypass channel 7, the surface cooler coil 2, the chilled water circulation loop 1, and the compressor 10.

[0073] If the second bypass channel 7 is open, the chilled water circulation loop 1 connected in parallel with the second bypass channel 7 is closed, the first bypass channel 4 is open, the surface cooler coil 2 is closed, and the compressor 10 is running, that is, the corresponding bypass valve 6 is open, the main control valve 5 is closed, the second and third ends of the three-way valve 3 are open (the surface cooler coil 2 is closed), and the compressor 10 is running, then the operating mode is determined to be the compressor refrigeration mode;

[0074] If the second bypass channel 7 is open, the chilled water circulation loop 1 connected in parallel with the second bypass channel 7 is closed, the first bypass channel 4 is closed, the surface cooler coil 2 is open, and the compressor 10 is running, that is, the corresponding bypass valve 6 is open, the main control valve 5 is closed, the first and second ends of the three-way valve 3 are open (the surface cooler coil 2 is open), and the compressor 10 is running, then the operating mode is determined to be the pre-cooling mode.

[0075] If the second bypass channel 7 is closed, the chilled water circulation loop 1 connected in parallel with the second bypass channel 7 is open, the first bypass channel 4 is closed, the surface cooler coil 2 is open, and the compressor 10 is closed, that is, the corresponding bypass valve 6 is closed, the main control valve 5 is open, the first and second ends of the three-way valve 3 are open (the surface cooler coil 2 is open), and the compressor 10 is closed, then the operating mode is determined to be the natural cooling mode.

[0076] Correspondingly, when the air conditioning unit operates in the different modes mentioned above, the states of the first bypass channel 4, the second bypass channel 7, the surface cooler coil 2, the chilled water circulation loop 1, and the compressor 10 should also remain corresponding.

[0077] The purpose of determining the current operating status of the air conditioning unit is to accurately determine the judgment conditions when switching to other modes, thereby ensuring that the air conditioning unit has a more precise control logic.

[0078] The above describes the automatic switching logic between different modes. Therefore, based on the automatic switching mode selected by the air conditioning unit, automatic and smooth switching between modes can be achieved. Furthermore, this application can also add semi-automatic and manual switching modes according to actual needs. For example, when the air conditioning unit selects the semi-automatic switching mode, it still follows the automatic switching logic described above, but adds a option for the user to manually confirm whether to switch modes. Clicking "Confirm" will cause the air conditioning unit to switch according to the automatic switching mode. If no operation is performed, after a preset time (2 minutes) or if the user "cancels," the current operating mode will continue to run. After a preset delay (5 minutes to 60 minutes), the user will again need to manually confirm whether to switch modes. As another example, when the air conditioning unit selects the manual switching mode, the unit only switches according to the manually set operating mode. The selectable modes for manually setting include compressor cooling mode, pre-cooling mode, and natural cooling mode. After manually setting the operating mode, the air conditioning unit adjusts from the current operating mode to the manually set operating mode.

[0079] It should be noted that for the above-mentioned automatic switching mode, semi-automatic switching mode and manual switching mode, the switching principle of the three operating modes should be followed: switching from compressor cooling mode to pre-cooling mode, pre-cooling mode to natural cooling mode, natural cooling mode to pre-cooling mode, and pre-cooling mode to compressor cooling mode, in order to prevent the problem of sudden rise and fall of temperature in the computer room.

[0080] The steps for automatically switching from compressor cooling mode to pre-cooling mode include:

[0081] The first bypass channel 4 is gradually shut off, and the corresponding surface cooler coil 2 will gradually open. The second bypass channel 7 is kept shut off, and the chilled water circulation loop 1 connected in parallel with the second bypass channel 7 is kept shut off. The compressor 10 is kept running in pre-cooling mode. When running pre-cooling mode, the compressor 10 adjusts its frequency according to the cooling demand of the machine room. The opening degree of the bypass valve 6 or the flow rate in the second bypass channel 7 is adjusted by PID according to the inlet and outlet water temperature difference of the surface cooler coil 2.

[0082] The steps for automatically switching from pre-cooling mode to natural cooling mode include:

[0083] The system controls the first bypass channel 4 to remain closed, the surface cooler coil 2 to remain open, and the compressor 10 to shut down. After the compressor 10 shuts down, the system controls the chilled water circulation loop 1, which is connected in parallel with the second bypass channel 7, to open for a delay (0s-300s). The second bypass channel 7 is then gradually shut off after the compressor 10 shuts down and after a delay (0s-300s) to operate in natural cooling mode. During natural cooling mode, the flow rate in the chilled water circulation loop 1 or the opening of the main control valve 5 is adjusted according to the actual supply air temperature. The main control valve 5 is opened and the bypass valve 6 is closed only after the compressor 10 shuts down, meaning the system switches to natural cooling mode only after the compressor 10 shuts down, preventing the compressor 10 from affecting the operation of natural cooling mode.

[0084] Meanwhile, during the switch from precooling mode to natural cooling mode, the flow rate in chilled water circulation loop 1 or the opening of main control valve 5 should be adjusted based on the temperature difference between the inlet and outlet water of surface cooler coil 2 to regulate the heat exchange capacity of surface cooler coil 2. That is, if the temperature difference between the inlet and outlet water of surface cooler coil 2 is too small, the opening of main control valve 5 should be increased to increase the flow rate through surface cooler coil 2; if the temperature difference between the inlet and outlet water of surface cooler coil 2 is too large, the opening of main control valve 5 should be decreased to reduce the flow rate through surface cooler coil 2, so as to maintain the cold source provided by surface cooler coil 2 and the cooling capacity required by the computer room within a roughly consistent range.

[0085] The steps for automatically switching from pre-cooling mode to compressor cooling mode include:

[0086] The control coil 2 of the surface cooler is gradually closed, while the first bypass channel 4 is gradually opened. The chilled water circulation loop 1, which is connected in parallel with the second bypass channel 7, is kept closed. The second bypass channel 7 is kept open. The compressor 10 is kept running in compressor cooling mode. When running compressor cooling mode, the compressor 10 adjusts its frequency according to the cooling demand of the computer room. The flow rate in the second bypass channel 7 or the opening degree of the bypass valve 6 is adjusted according to the temperature difference between the inlet and outlet water of the surface cooler coil 2.

[0087] The steps for automatically switching from natural cooling mode to pre-cooling mode include:

[0088] The chilled water circulation loop 1, which is connected in parallel with the second bypass channel 7, is shut off. The second bypass channel 7 remains open. During the shutdown of the chilled water circulation loop 1, the flow rate in the second bypass channel 7 is adjusted based on the current flow rate of the chilled water circulation loop 1 and the temperature difference between the inlet and outlet water of the surface cooler coil 2. Specifically, the opening degree of the bypass valve 6 is the current opening degree of the main control valve 5 plus a set opening value. This set opening value is determined based on the temperature difference between the inlet and outlet water of the surface cooler coil 2. This can adjust the flow rate of chilled water flowing into the condenser 9 to maintain sufficient heat release from the refrigerant. After the second bypass channel 7 is opened, the compressor 10 is controlled to run for a delay (0s-120s), the surface cooler coil 2 remains open, and the first bypass channel 4 remains closed to operate in pre-cooling mode. In pre-cooling mode, the compressor 10 adjusts its frequency according to the cooling demand of the machine room, and the flow rate in the second bypass channel 7 or the opening degree of the bypass valve 6 is adjusted according to the temperature difference between the inlet and outlet water of the surface cooler coil 2.

[0089] It should be noted that the preset time, preset supply air temperature, and preset return air temperature mentioned above are all manually set and can be obtained through multiple tests based on actual working conditions. All parameters, including but not limited to those given above, fall within the scope of protection of this application.

[0090] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0091] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A control method for a dual-source air conditioning unit, characterized in that, Applied to dual-source air conditioning units, the dual-source air conditioning unit includes: The natural cooling system includes a chilled water circulation loop (1) and a surface cooler coil (2) provided on the chilled water circulation loop (1). Along the flow path of chilled water in the chilled water circulation loop (1), a first bypass channel (4) and a second bypass channel (7) are provided in sequence on the chilled water circulation loop (1). The first bypass channel (4) is connected in parallel with the surface cooler coil (2). The compressor refrigeration system includes a compressor (10), an evaporator (12), a condenser (9), and a throttling element. The compressor (10), the evaporator (12), the condenser (9), and the throttling element are connected to form a refrigerant circulation loop (8). The temperature detection system includes several temperature sensors (13), which are used to detect the supply air temperature of the air conditioning unit, the inlet and outlet water temperatures of the surface cooler coil (2), and the return air temperature of the air conditioning unit. In this process, the chilled water in the second bypass channel (7) exchanges heat with the refrigerant in the condenser (9) to remove the heat from the refrigerant; The control method includes: The current operating mode of the air conditioning unit is determined, including: compressor cooling mode, pre-cooling mode, and natural cooling mode. In the compressor cooling mode, the second bypass channel (7) is open, the chilled water circulation loop (1) corresponding to the second bypass channel (7) is closed, the first bypass channel (4) is open, the surface cooler coil (2) is closed, and the compressor (10) is running. In the pre-cooling mode, the second bypass channel (7) is open, the chilled water circulation loop (1) corresponding to the second bypass channel (7) is closed, the first bypass channel (4) is closed, the surface cooler coil (2) is open, and the compressor (10) is running. In the natural cooling mode, the second bypass channel (7) is closed, the chilled water circulation loop (1) corresponding to the second bypass channel (7) is open, the first bypass channel (4) is closed, the surface cooler coil (2) is open, and the compressor (10) is closed. When the compressor is running in cooling mode, if the inlet water temperature of the surface cooler coil (2) is less than or equal to the return air temperature of the machine room and continues for a preset time, the compressor will automatically switch to running the pre-cooling mode. When the pre-cooling mode is running, if the inlet water temperature is less than or equal to the preset air supply temperature of the computer room, and the compressor (10) runs at the minimum frequency for a preset time, then the system will automatically switch to the natural cooling mode; or, if the actual air supply temperature of the computer room is less than the preset air supply temperature, and the compressor (10) runs at the minimum frequency for a preset time, then the system will automatically switch to the natural cooling mode. When the precooling mode is running, if the inlet water temperature is greater than the return air temperature and this continues for a preset time, the system will automatically switch to the compressor cooling mode. When the natural cooling mode is running, if the flow rate in the chilled water circulation loop (1) is greater than or equal to the preset flow rate, and the actual air supply temperature is greater than the preset air supply temperature for a preset time, then the system will automatically switch to the pre-cooling mode; or, if the inlet water temperature is greater than or equal to the preset air supply temperature for a preset time, then the system will automatically switch to the pre-cooling mode.

2. The control method according to claim 1, characterized in that, The condenser (9) is a condenser plate heat exchanger. The condenser plate heat exchanger is provided with a second passage that is connected to the second bypass passage. The condenser plate heat exchanger is also provided with a first passage that is connected to the refrigerant circulation loop (8). The first passage and the second passage are set independently.

3. The control method according to claim 2, characterized in that, The evaporator (12) is an evaporator coil. The evaporator coil has a third passage that is connected to the refrigerant circulation loop (8). The evaporator coil and the surface cooler coil (2) are positioned corresponding to each other and connected in series in the airflow direction so that the return air of the machine room passes through the surface cooler coil (2) and the evaporator coil and is then sent into the machine room.

4. The control method according to claim 3, characterized in that, The compressor refrigeration system consists of two sets, which share one condenser heat exchanger and one evaporator coil. The condenser heat exchanger has two first passages, which are independently configured. The evaporator coil has two third passages, which are intersecting and independently configured.

5. The control method according to claim 1, characterized in that, The step of determining the current operating mode of the air conditioning unit includes: When the air conditioning unit is started, if the inlet water temperature is greater than or equal to the preset return air temperature, it is started in the compressor cooling mode, and the current operating mode is the compressor cooling mode; if the preset supply air temperature is less than the inlet water temperature and less than the preset return air temperature, it is started in the pre-cooling mode, and the current operating mode is the pre-cooling mode; if the inlet water temperature is less than or equal to the preset supply air temperature, it is started in the natural cooling mode, and the current operating mode is the natural cooling mode; during the operation of the air conditioning unit, the current operating mode of the air conditioning unit is determined based on the current status of the surface cooler coil (2), the first bypass channel (4), the second bypass channel (7), the chilled water circulation loop (1), and the compressor (10); If the second bypass channel (7) is open, the chilled water circulation loop (1) corresponding to the second bypass channel (7) is closed, the first bypass channel (4) is open, the surface cooler coil (2) is closed, and the compressor (10) is running, then the operating mode is determined to be the compressor refrigeration mode; If the second bypass channel (7) is open, the chilled water circulation loop (1) corresponding to the second bypass channel (7) is closed, the first bypass channel (4) is closed, the surface cooler coil (2) is turned on, and the compressor (10) is running, then the operating mode is determined to be the pre-cooling mode; If the second bypass channel (7) is closed, the chilled water circulation loop (1) connected in parallel with the second bypass channel (7) is open, the first bypass channel (4) is closed, the surface cooler coil (2) is turned on, and the compressor (10) is turned off, then the operating mode is determined to be the natural cooling mode.

6. The control method according to claim 5, characterized in that, The steps of automatically switching from the compressor cooling mode to the pre-cooling mode include: The first bypass channel (4) is gradually shut off, while the surface cooler coil (2) is gradually opened. The second bypass channel (7) is kept shut off, and the chilled water circulation loop (1) connected in parallel with the second bypass channel (7) is kept shut off. The compressor (10) is kept running to operate the pre-cooling mode. When operating the pre-cooling mode, the compressor (10) adjusts its frequency according to the cooling demand of the machine room. The flow rate in the second bypass channel (7) is adjusted according to the temperature difference between the inlet and outlet water of the surface cooler coil (2).

7. The control method according to claim 5, characterized in that, The steps for automatically switching from the pre-cooling mode to the natural cooling mode include: The first bypass channel (4) is kept off, the surface cooler coil (2) is kept on, the compressor (10) is shut off, and after the compressor (10) is shut off, the chilled water circulation loop (1) corresponding to the second bypass channel (7) is delayed in being turned on. The second bypass channel (7) is controlled to shut off after the compressor (10) is shut off and delayed in order to run the natural cooling mode. When running the natural cooling mode, the flow rate in the chilled water circulation loop (1) is adjusted according to the actual air supply temperature.

8. The control method according to claim 5, characterized in that, The steps for automatically switching from the pre-cooling mode to the compressor cooling mode include: The surface cooler coil (2) is gradually closed, while the first bypass channel (4) is gradually opened. The chilled water circulation loop (1) connected in parallel with the second bypass channel (7) is kept closed. The second bypass channel (7) is kept open. The compressor (10) is kept running to run the compressor cooling mode. When running the compressor cooling mode, the compressor (10) adjusts its frequency according to the cooling demand of the machine room. The flow rate in the second bypass channel (7) is adjusted according to the temperature difference between the inlet and outlet water of the surface cooler coil (2).

9. The control method according to claim 5, characterized in that, The steps for automatically switching from the natural cooling mode to the pre-cooling mode include: The chilled water circulation loop (1) corresponding to the second bypass channel (7) is shut off, the second bypass channel (7) is kept open, and during the shutdown of the chilled water circulation loop (1), the flow rate in the second bypass channel (7) is adjusted based on the current flow rate of the chilled water circulation loop (1) and the inlet and outlet water temperature difference of the surface cooler coil (2). After the second bypass channel (7) is opened, the compressor (10) is delayed in operation, the surface cooler coil (2) is kept open, and the first bypass channel (4) is kept closed to run the pre-cooling mode. When running the pre-cooling mode, the compressor (10) adjusts the frequency according to the cooling demand of the machine room, and the flow rate in the second bypass channel (7) is adjusted according to the inlet and outlet water temperature difference.

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