Dual cold source air conditioning unit and control method

Abstract

This application discloses a dual-source air conditioning unit and its control method, relating to the field of computer room air conditioning technology. The air conditioning unit includes a chilled water system, a refrigerant system, and a temperature detection system. The chilled water system includes a chilled water circulation loop and chilled water coils installed on the chilled water circulation loop, and a control valve is also provided on the chilled water circulation loop. The refrigerant system includes a compressor, a refrigerant pump, an evaporator, a condenser, and a throttling element, which are connected to form the refrigerant circulation loop of the refrigerant system. The temperature detection system includes several temperature sensors used to detect the supply air temperature of the air conditioning unit, the inlet water temperature of the chilled water coils, and the return air temperature of the air conditioning unit. This application avoids the cumbersome manual switching and the resulting increase in computer room temperature caused by untimely system switching.

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 units typically employ a parallel configuration of a chilled water cooling system and a refrigerant refrigeration system to provide sufficient cooling capacity for data centers, 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] When the chilled water cooling system, which serves as the primary cooling mode, malfunctions, it is necessary to manually switch to the refrigerant system, which serves as the backup cooling mode, to maintain the temperature within the computer room. Alternatively, after the chilled water cooling system returns to normal, it is also necessary to manually switch the refrigerant cooling system back to chilled water cooling mode. These manual switching processes are cumbersome and can cause the temperature within the computer room to rise rapidly, jeopardizing the reliability of the computer room's operation.

[0005] Therefore, in view of the above-mentioned technical problems, how to avoid the rise in computer room temperature caused by untimely system switching 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 avoids the cumbersome manual switching and the temperature rise in the computer room caused by untimely system switching.

[0007] To achieve the above objectives, this application provides a dual-source air conditioning unit, including a chilled water system, a refrigerant system, and a temperature detection system;

[0008] The chilled water system includes a chilled water circulation loop and a chilled water coil installed on the chilled water circulation loop, and a control valve is also provided on the chilled water circulation loop;

[0009] The fluorine system includes a compressor, a fluorine pump, an evaporator, a condenser, and a throttling element. The compressor, the fluorine pump, the evaporator, the condenser, and the throttling element are connected to form the fluorine circulation loop of the fluorine system.

[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 water temperature of the chilled water coil, and the return air temperature of the air conditioning unit.

[0011] Preferably, the number of fluorine systems is two sets, and the evaporators in the two sets of fluorine systems are arranged one after the other according to the return air direction, so that the return air of the machine room passes through the two evaporators in sequence and is sent into the machine room by the indoor fan.

[0012] Preferably, the evaporator is an evaporation coil, and the chilled water coil is positioned corresponding to the evaporation coil, so that the return air from the computer room passes through the chilled water coil and the evaporation coil in sequence before being supplied to the computer room.

[0013] A control method, applied to the aforementioned dual-source air conditioning unit, the control method comprising:

[0014] The system determines whether an automatic mode switching signal has been received while the air conditioning unit is running. If yes, the air conditioning unit automatically runs in chilled water mode; otherwise, the system controls the air conditioning unit to run in manual mode.

[0015] When the air conditioning unit is running in the chilled water mode, the air conditioning unit automatically detects whether the chilled water system is faulty. If so, the air conditioning unit automatically switches to the refrigerant mode; otherwise, it continues to run in the chilled water mode.

[0016] After the air conditioning unit automatically switches to the refrigerant mode, the air conditioning unit automatically detects whether the fault in the chilled water system has been eliminated. If so, the air conditioning unit automatically switches to the chilled water mode; otherwise, it continues to operate in the refrigerant mode.

[0017] Preferably, the step of automatically detecting whether the chilled water system is faulty when the air conditioning unit is operating in the chilled water mode includes:

[0018] Determine whether the actual supply air temperature of the air conditioning unit is higher than the preset supply air temperature. If not, the chilled water system is fault-free. If so, check whether the control valve is faulty or at its maximum opening. If the control valve is faulty or at its maximum opening for a preset time, the chilled water system is determined to be faulty.

[0019] Preferably, after the air conditioning unit automatically switches to the refrigerant mode, it further includes:

[0020] Determine whether the inlet water temperature of the chilled water coil is higher than the return air temperature of the air conditioning unit. If so, control the opening of the control valve to the minimum opening; otherwise, control the opening of the control valve to the maximum opening.

[0021] Adjust the compressor operating frequency of the refrigerant system based on the heat exchange capacity of the chilled water coil and the cooling requirements of the computer room.

[0022] Preferably, the air conditioning unit automatically detects whether the fault in the chilled water system has been eliminated, including:

[0023] When the compressor is running at its lowest frequency, it is determined whether the actual air supply temperature of the air conditioning unit is less than or equal to the preset air supply temperature. If so, the chilled water system fault is eliminated after the refrigerant system has been running for a preset time; otherwise, the chilled water system fault is not eliminated.

[0024] Preferably, after the fluoride system has been running for a preset time and the chilled water system malfunction has been resolved, the process further includes:

[0025] Control the shutdown of the fluorine system and detect the current opening degree of the control valve;

[0026] If the control valve is at its maximum opening, then the chilled water mode is activated;

[0027] If the control valve is at its minimum opening, the computer room has no cooling requirement, and the air conditioning unit enters standby mode.

[0028] Preferably, when the air conditioning unit is running, the control valve is controlled to maintain at least the minimum opening degree in the non-closed state.

[0029] Preferably, when the air conditioning unit is operating in the chilled water mode, the opening degree of the control valve is adjusted according to the cooling demand of the computer room. After the opening degree of the control valve reaches the minimum opening degree and remains so for a preset time, the computer room has no cooling demand, and the air conditioning unit enters the standby state.

[0030] Compared with the prior art, the technical solution provided in this application has at least the following beneficial effects:

[0031] The air conditioning unit of this application can select an automatic switching mode, with the chilled water system as the primary cooling mode. When the chilled water system fails, the air conditioning unit can automatically switch to the backup refrigerant system cooling mode to meet the cooling demand of the computer room and prevent the temperature inside the computer room from rising. Simultaneously, the air conditioning unit can detect whether the chilled water system has returned to normal. When the chilled water system returns to normal, the air conditioning unit can automatically switch to the chilled water system, similarly preventing the temperature inside the computer room from rising. This air conditioning unit avoids the cumbersome manual switching and the temperature rise in the computer room caused by untimely system switching.

[0032] In addition, the air conditioning unit of this application can also select a manual mode. For chilled water systems that require regular maintenance, the refrigerant system cooling mode can be manually selected, and the system can be switched back to chilled water mode after maintenance is completed. This is convenient, quick, and has a wider range of applications. Attached Figure Description

[0033] 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.

[0034] Figure 1 This is a schematic diagram of the dual-cooling-source air conditioning unit provided in the embodiments of this application;

[0035] Figure 2 This is a flowchart of the control method provided in an embodiment of this application.

[0036] In the picture:

[0037] 1-Compressor; 2-Evaporator; 3-Condenser; 4-Freon pump; 5-Freon circulation loop; 6-Throttling element; 7-Chiller coil; 8-Cooling unit; 9-Chiller circulation loop; 10-Control valve. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] 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.

[0041] like Figure 1 As shown in this embodiment, a dual-source air conditioning unit is provided. The air conditioning unit includes a chilled water system, a refrigerant system, and a temperature detection system. The chilled water system serves as the main refrigeration system, and the refrigerant system serves as a backup refrigeration system. When the chilled water system fails or needs maintenance, the backup refrigerant system can be activated for refrigeration, thereby preventing the computer room temperature from becoming too high.

[0042] The chilled water system includes a chilled water circulation loop 9 and chilled water coils 7 installed on the chilled water circulation loop 9. Circulating water can flow in the circulation loop, allowing it to exchange heat with the return air from the computer room when it reaches the chilled water coils 7. After the heat exchange with the return air, air is then supplied to the computer room. The chilled water system also includes a cooling unit 8, which is also installed on the chilled water circulation loop 9. When the circulating water exchanges heat with the return air from the computer room, its temperature rises. The heated circulating water can then exchange heat at the cooling components, releasing the heat to the outdoor environment, and then flows back through the circulation loop to the chilled water coils 7, achieving circulating water heat exchange.

[0043] In addition, a control valve 10 is provided on the chilled water circuit. The control valve 10 can control the flow rate of circulating water in the circulation circuit according to its opening degree, thereby changing the heat exchange capacity of the chilled water coil 7. The control valve 10 can be an electromagnetic control valve, which can automatically adjust its opening degree and monitor its opening status.

[0044] Among them, the cooling unit 8 can be an air-cooled cooling unit, a water-cooled cooling zone unit, an evaporative cooling unit, etc., as long as it can achieve the cooling of the circulating water. They will not be described in detail here, but all fall within the scope of protection of this application.

[0045] The fluorine system includes a compressor 1, a fluorine pump 4, an evaporator 2, and a condenser 3. These four components are connected to form the fluorine circulation loop 5 of the fluorine system. The fluorine system also includes components such as a throttling element 6 and temperature and pressure sensors. The throttling element 6 can be an electronic expansion valve, which will not be elaborated here but can be found in existing technologies.

[0046] Once the air conditioning unit is started and running, if the computer room has a cooling demand, at least one of the refrigerant system and the chilled water system can provide cooling capacity to meet the cooling demand of the computer room.

[0047] The temperature detection system includes several temperature sensors, which can be installed on the supply air side of the air conditioning unit, the inlet water side of the chilled water coil 7, and the return air side of the air conditioning unit, respectively, to detect the supply air temperature, the inlet water temperature of the chilled water coil 7, and the return air temperature of the air conditioning unit. Alternatively, pressure sensors can be installed on the inlet and outlet water sides of the chilled water coil 7 to detect the pressure difference between the inlet and outlet water of the chilled water coil 7, depending on the actual situation.

[0048] The air conditioning unit of this application has an automatic switching function. The chilled water system is the main cooling method. After the automatic switching function is activated, the chilled water system can be turned on first, so that the air conditioning unit can operate in chilled water mode to provide sufficient cooling capacity according to the actual cooling capacity demand of the computer room.

[0049] During the operation of the air conditioning unit in chilled water mode, the chilled water system can adjust its cooling capacity according to the actual cooling demand of the computer room. Therefore, when the chilled water system is operating normally, the unit's supply air temperature can be kept less than or equal to the preset value to meet the cooling demand of the computer room. If the unit's supply air temperature exceeds the preset value at a certain moment or during a certain period, it indicates that the chilled water system may be malfunctioning. Among these, insufficient circulating water flow in the chilled water coil 7, high circulating water inlet temperature, and malfunction of control valve 10 can all cause the unit's supply air temperature to exceed the preset value.

[0050] When the chilled water system malfunctions, the unit's supply air temperature can no longer meet the cooling demand of the computer room. In this case, the refrigerant system can be automatically activated, and the air conditioning unit can operate in refrigerant mode to provide cooling through the backup refrigerant system, thereby preventing the temperature inside the computer room from rising.

[0051] When the air conditioning unit is running in refrigerant mode, it can also detect whether the chilled water has returned to normal. If it has not returned to normal, it will continue to run in refrigerant system mode; if it has returned to normal, it will switch back to the chilled water system, thereby realizing automatic switching between the refrigerant system and the chilled water system.

[0052] In addition, the air conditioning unit of this application also has a manual switching function. When the chilled water system is ready for regular maintenance, it is manually switched to the refrigerant system mode. When the chilled water system maintenance is completed, the system is manually switched back to the chilled water mode.

[0053] As can be seen, the chilled water system of this application can determine the operating status in real time by the air outlet temperature of the air conditioning unit, and quickly make corresponding switches according to different statuses, so that the air conditioning unit can effectively control the temperature of the computer room and avoid the temperature rise during the switching process.

[0054] In summary, the air conditioning unit of this application can select an automatic switching mode, with the chilled water system as the primary cooling mode. When the chilled water system malfunctions, the air conditioning unit can automatically switch to the backup refrigerant system cooling mode to meet the cooling demand of the computer room and prevent the temperature inside the computer room from rising. Simultaneously, the air conditioning unit can detect whether the chilled water system has returned to normal. When the chilled water system returns to normal, the air conditioning unit can automatically switch back to the chilled water system, similarly preventing the temperature inside the computer room from rising. This air conditioning unit avoids the cumbersome manual switching and the temperature rise in the computer room caused by untimely system switching. The air conditioning unit of this application can also select a manual mode. For chilled water systems that require regular maintenance, the refrigerant system cooling mode can be manually selected, and the system can be switched back to the chilled water mode after maintenance is completed, which is convenient, quick, and has a wider range of applications.

[0055] The fluorine system of this application consists of two sets. The evaporators 2 in the two sets of fluorine systems are arranged one after the other according to the return air direction, so that the return air of the computer room passes through the two evaporators 2 in sequence and is sent into the computer room by the indoor fan.

[0056] The two refrigerant systems can provide sufficient cooling capacity for the computer room when the chilled water coil 7 fails or is under maintenance. At the same time, the two refrigerant systems can operate independently or simultaneously. When the chilled water coil 7 fails but can still provide a certain amount of cooling capacity, only one refrigerant system can be turned on to work with the chilled water system, thus saving data center power resources while meeting the cooling capacity requirements of the computer room.

[0057] The evaporator 2 of the refrigerant system can be an evaporator coil. The chilled water coil 7 corresponds to the evaporator coil, so that the return air from the machine room passes sequentially through the chilled water coil 7 and the evaporator coil before being supplied to the machine room. At least one of the chilled water coil 7 and the evaporator coil can exchange heat with the return air from the machine room to reduce the heat of the return air. Of course, the evaporator coil can also be a cross-type evaporator coil, that is, two sets of refrigerant systems correspond to one evaporator coil. The evaporator coil has two independent channels corresponding to the refrigerant circulation loops 5 of the two sets of refrigerant systems. The two independent channels are arranged crosswise. This will not be described in detail here, but both fall within the scope of protection of this application.

[0058] This application also provides a control method applicable to the aforementioned dual-source air conditioning unit. Please refer to [reference needed]. Figure 2 The control method includes:

[0059] After the air conditioning unit starts up, you can choose between automatic or manual switching mode depending on the actual situation. When the chilled water system needs maintenance, you can choose manual switching mode and select the refrigerant system for cooling. Otherwise, you can choose automatic switching mode. Of course, in manual switching mode, if the chilled water system is in normal condition, you can also choose to run the chilled water system. Normal chilled water system conditions include no alarm at the inlet water temperature of chilled water coil 7 (the inlet water temperature of chilled water coil 7 must be lower than the supply air temperature of the machine room) and the inlet and outlet water pressure difference (temperature difference) of chilled water coil 7 being greater than the set value.

[0060] Since the chilled water system is the main refrigeration system, the air conditioning unit will automatically operate in chilled water mode after the automatic switching mode is selected. When the air conditioning unit is operating in chilled water mode, it will automatically detect whether there is a fault in the chilled water system in real time. If a fault is found, the air conditioning unit will automatically switch to refrigerant mode; if there is no fault, it will continue to operate in chilled water mode. Based on the above, the air conditioning unit can quickly make corresponding judgments according to the operating status of the chilled water system (fault status and non-fault status), ensuring the stability of the computer room temperature.

[0061] After the air conditioning unit automatically switches to refrigerant mode, it can automatically detect whether the fault in the chilled water system has been eliminated. If so, the air conditioning unit will automatically switch to chilled water mode; otherwise, it will continue to run in refrigerant mode. This will allow the chilled water system to return to normal and then automatically switch back to chilled water mode, ensuring that the chilled water system is the main refrigeration system.

[0062] The steps for automatically detecting whether the chilled water system is faulty when the air conditioning unit is operating in chilled water mode include:

[0063] Determine if the actual supply air temperature of the air conditioning unit is higher than the preset supply air temperature. If not, it means the chilled water system can meet the cooling demand of the computer room, and the chilled water system is fault-free and can operate continuously. If it is, it means the chilled water system cannot meet the cooling demand of the computer room. In this case, it is necessary to check whether the control valve 10 is faulty or at its maximum opening. Specifically, if a fault is detected in the control valve 10 and it continues for a preset time, it means the chilled water system is faulty. Alternatively, if the chilled water system still cannot meet the cooling demand of the computer room when the control valve 10 is at its maximum opening, it means the circulating water flow in the chilled water system is insufficient or the circulating water inlet temperature is too high, which also indicates a fault in the chilled water system.

[0064] In general, when the air conditioning unit is running in chilled water mode, if the actual supply air temperature of the air conditioning unit is higher than the preset supply air temperature, it indicates a fault in the chilled water system. For specific fault types, please refer to the above content.

[0065] The steps following the automatic switching of the air conditioning unit to refrigerant mode also include:

[0066] Determine whether the inlet water temperature of chilled water coil 7 is higher than the return air temperature of the air conditioning unit. If so, it means that chilled water coil 7 can no longer cool the return air of the computer room, so the opening of control valve 10 needs to be controlled to the minimum opening. If not, it means that chilled water coil 7 still has a cooling function, and the opening of control valve 10 can be controlled to the maximum opening, so as to provide a certain amount of cooling capacity for the return air of the computer room.

[0067] However, regardless of whether control valve 10 is at its minimum or maximum opening, the cooling capacity provided by the chilled water system is insufficient to meet the cooling demand of the computer room. Therefore, the refrigerant system can supplement the computer room with sufficient cooling capacity based on the current heat exchange capacity of the chilled water coil 7 and the cooling demand of the computer room. It should be noted that after a failure of the chilled water system, there will be a gradual recovery process. The chilled water system can be restored to normal through maintenance by staff. At this time, the heat exchange capacity of the chilled water coil 7 will gradually increase. Therefore, the operating frequency of the compressor 1 of the refrigerant system also needs to be changed accordingly to meet the cooling demand of the computer room.

[0068] In addition, the steps for the air conditioning unit to automatically detect whether the fault in the chilled water system has been eliminated include:

[0069] When compressor 1 is running at its lowest frequency, determine whether the actual air supply temperature of the air conditioning unit is less than or equal to the preset air supply temperature. If so, the chilled water system fault will be eliminated after the refrigerant system has been running for a preset time; otherwise, the chilled water system fault will not be eliminated.

[0070] It should be noted that as the chilled water system gradually returns to normal, the cooling capacity provided by the chilled water coil 7 gradually increases. Consequently, the refrigerant system will reduce the operating frequency of the compressor 1. When the compressor 1 reaches its lowest frequency, if the actual air supply temperature of the air conditioning unit is less than or equal to the preset air supply temperature, it indicates that the cooling capacity provided by the chilled water system can meet the cooling demand of the computer room. After maintaining this position for a preset time, the chilled water system fault is eliminated.

[0071] After the fluoride system has been running for a preset time and the chilled water system malfunction has been resolved, the following steps are taken:

[0072] Shut down the refrigerant system and check the opening degree of the current control valve 10;

[0073] If control valve 10 is at its maximum opening, it means that the computer room still needs the chilled water system to provide cooling capacity, and the air conditioning unit is running in chilled water mode.

[0074] If control valve 10 is at its minimum opening, the chilled water system does not provide cooling capacity at this time. At the same time, with the refrigerant system off, the actual supply air temperature of the air conditioning unit is less than or equal to the preset supply air temperature, indicating that the computer room has no cooling capacity requirement. Even when neither the chilled water system nor the refrigerant system is running, the computer room still meets the cooling capacity requirement (when the computer room has no cooling capacity requirement, the fact that neither the chilled water system nor the refrigerant system provides cooling capacity can also be considered as meeting the cooling capacity requirement of the computer room). At this time, the air conditioning unit can enter standby mode for further control.

[0075] It should be noted that when the air conditioning unit is running, regardless of the switching mode or whether the chilled water system is running, the control valve 10 should be kept at least at the minimum opening in the non-closed state to provide a more accurate temperature difference and pressure difference between the inlet and outlet water of the chilled water coil 7.

[0076] Furthermore, regardless of whether the air conditioning unit operates in chilled water mode directly through automatic switching, manual switching, or by switching to chilled water mode via the refrigerant system, the refrigerant system is always off during chilled water operation. This means compressor 1 and refrigerant pump 4 are not running. The chilled water system can automatically adjust the opening of control valve 10 according to the cooling demand of the computer room. If, under fault-free conditions, the control valve 10 reaches its minimum opening and remains there for a preset time, it indicates that there is no cooling demand in the computer room, and the air conditioning unit can enter standby mode. During the reduction of the opening of control valve 10, it should be gradually reduced by a small increment, which can be set according to the specific characteristics of control valve 10.

[0077] 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.

[0078] 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 dual-source air conditioning unit, characterized in that, This includes chilled water systems, fluoride systems, and temperature monitoring systems; The chilled water system includes a chilled water circulation loop (9) and a chilled water coil (7) provided on the chilled water circulation loop (9). The chilled water circulation loop (9) is also provided with a control valve (10). The fluorine system includes a compressor (1), a fluorine pump (4), an evaporator (2), a condenser (3), and a throttling element (6). The compressor (1), the fluorine pump (4), the evaporator (2), the condenser (3), and the throttling element (6) are connected to form the fluorine circulation loop (5) of the fluorine system. The temperature detection system includes several temperature sensors, which are used to detect the supply air temperature of the air conditioning unit, the inlet water temperature of the chilled water coil (7), and the return air temperature of the air conditioning unit. The evaporator (2) in the fluorine system is arranged front and back according to the return air direction, so that the return air of the machine room passes through the two evaporators (2) in sequence and is sent into the machine room by the indoor fan; The evaporator (2) is an evaporation coil, and the chilled water coil (7) is positioned corresponding to the evaporation coil so that the return air from the machine room passes through the chilled water coil (7) and the evaporation coil in sequence before being sent into the machine room.

2. A control method, characterized in that, The control method, applied to the dual-source air conditioning unit of claim 1, includes: Determine whether an automatic mode switching signal is received during the operation of the air conditioning unit. If yes, control the air conditioning unit to automatically operate in chilled water mode; otherwise, control the air conditioning unit to operate in manual switching mode. When the air conditioning unit is running in the chilled water mode, the air conditioning unit automatically detects whether the chilled water system is faulty. If so, the air conditioning unit automatically switches to the refrigerant mode; otherwise, it continues to run in the chilled water mode. After the air conditioning unit automatically switches to the refrigerant mode, the air conditioning unit automatically detects whether the fault in the chilled water system has been eliminated. If so, the air conditioning unit automatically switches to the chilled water mode; otherwise, it continues to operate in the refrigerant mode.

3. The control method according to claim 2, characterized in that, The step of automatically detecting whether the chilled water system is faulty when the air conditioning unit is operating in the chilled water mode includes: Determine whether the actual supply air temperature of the air conditioning unit is higher than the preset supply air temperature. If not, the chilled water system is fault-free. If so, check whether the control valve (10) is faulty or at its maximum opening. If the control valve (10) is faulty or at its maximum opening and remains so for a preset time, the chilled water system is faulty.

4. The control method according to claim 3, characterized in that, After the air conditioning unit automatically switches to the refrigerant mode, it further includes: Determine whether the inlet water temperature of the chilled water coil (7) is higher than the return air temperature of the air conditioning unit. If yes, control the opening of the control valve (10) to the minimum opening; if no, control the opening of the control valve (10) to the maximum opening. Adjust the operating frequency of the compressor (1) of the refrigerant system according to the heat exchange capacity of the chilled water coil (7) and the cooling demand of the computer room.

5. The control method according to claim 4, characterized in that, The air conditioning unit automatically detects whether the fault in the chilled water system has been eliminated, including: When the compressor (1) is running at its lowest frequency, it is determined whether the actual air supply temperature of the air conditioning unit is less than or equal to the preset air supply temperature. If so, the chilled water system fault is eliminated after the refrigerant system has been running for a preset time. If not, the chilled water system fault is not eliminated.

6. The control method according to claim 5, characterized in that, After the fluoride system has been running for a preset time and the chilled water system malfunction has been resolved, the process further includes: Control the shutdown of the fluorine system and detect the current opening degree of the control valve (10); If the control valve (10) is at its maximum opening, then the chilled water mode is operated; If the control valve (10) is at its minimum opening, then the computer room has no cooling demand and the air conditioning unit enters standby mode.

7. The control method according to any one of claims 3-6, characterized in that, When the air conditioning unit is running, the control valve (10) is controlled to be kept at least at the minimum opening degree in the non-closed state.

8. The control method according to claim 7, characterized in that, When the air conditioning unit is running the chilled water mode, the opening of the control valve (10) is adjusted according to the cooling demand of the computer room. After the opening of the control valve (10) reaches the minimum opening and continues for a preset time, the computer room has no cooling demand and the air conditioning unit enters the standby state.

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