Combined air-conditioning unit and control method

Abstract

A combined air-conditioning unit and a control method, relating to the technical field of computer room air conditioners. The combined air-conditioning unit comprises an outdoor heat exchange system and an indoor heat exchange system. The outdoor heat exchange system comprises a main circuit, a first condenser, and a pressure pump, wherein a plurality of branches corresponding to the indoor heat exchange system are provided on the main circuit. The indoor heat exchange system comprises a compressor, a second condenser, a throttling element, and a second evaporator. One indoor heat exchange system at least corresponds to two branches, one of the branches is provided with a first electric control valve and a first evaporator which are connected in series, and the other of the branches is provided with a second electric control valve and exchanges heat with the second condenser to remove heat from a refrigerant in the indoor heat exchange system. The first evaporator and the second evaporator both are arranged indoors, at least one of the first and second evaporators provides cooling capacity for the indoor space, and the first and second evaporators are arranged in series in an airflow direction. The present application can operate in different cooling modes on the basis of different outdoor operating conditions, thereby utilizing outdoor natural cold sources to the maximum extent.

Description

A composite air conditioning unit and its control method

[0001] This application claims priority to Chinese Patent Application No. 202411878496.2, filed on December 18, 2024, entitled "A Composite Air Conditioning Unit and Control Method", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of computer room air conditioning technology, and in particular to a composite air conditioning unit and its control method. Background Technology

[0003] Most existing large data center computer rooms use indirect evaporative chillers, refrigerant pump multi-split units, etc., while traditional room-level and row-level air conditioners are mostly used in small computer rooms, power distribution rooms and battery rooms due to their low energy efficiency ratio.

[0004] In the process of realizing this invention, the inventors discovered that the prior art has at least the following problems:

[0005] Existing air conditioning units cannot automatically adjust their operating modes according to different outdoor conditions, resulting in the air conditioning units not being able to fully utilize outdoor natural cooling sources, leading to lower cooling efficiency and increased power consumption in data centers.

[0006] Therefore, in view of the above-mentioned technical problems, how to maximize the use of outdoor natural cold sources while ensuring the cooling efficiency of air conditioning units is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this application is to provide a composite air conditioning unit and control method that can operate in different cooling modes according to different outdoor conditions, so as to make the maximum use of outdoor natural cold sources.

[0008] To achieve the above objectives, this application provides a composite air conditioning unit, including an outdoor heat exchange system and an indoor heat exchange system. The outdoor heat exchange system includes a main circuit for refrigerant flow, a first condenser and a pressure pump are provided on the main circuit, the first condenser exchanges heat with the external environment, and the main circuit is provided with several branches corresponding to the indoor heat exchange system.

[0009] The indoor heat exchange system includes a compressor, a second condenser, a throttling element, and a second evaporator, which are connected to form a refrigerant circulation loop of the indoor heat exchange system. The indoor heat exchange system is at least one set, and each set of the indoor heat exchange system corresponds to at least two branches. In the two branches, one branch is connected in series with a first electrically controlled valve and a first evaporator, and the other branch is equipped with a second electrically controlled valve and exchanges heat with the second condenser to remove the heat of the refrigerant in the indoor heat exchange system.

[0010] Both the first evaporator and the second evaporator are located indoors, and at least one of the first evaporator and the second evaporator provides cooling capacity to the room. The first evaporator and the second evaporator are connected in series in the airflow direction.

[0011] Preferably, the first condenser is an evaporative condenser, which includes a heat exchange coil connected to the main circuit. An external fan is provided on one side of the heat exchange coil. The evaporative condenser also includes a spray device that sprays water onto the heat exchange coil. A temperature and / or pressure sensor is provided at the outlet end of the heat exchange coil to detect the refrigerant temperature and / or pressure at the outlet of the evaporative condenser.

[0012] Preferably, the refrigerant in the outdoor heat exchange system and the refrigerant in the indoor heat exchange system are fluorinated refrigerants.

[0013] Preferably, the outdoor heat exchange system further includes a liquid storage tank located on the main circuit, and the number of pressure pumps is at least two, which are connected in parallel and located at the outlet end of the liquid storage tank.

[0014] A control method, applied to the aforementioned combined air conditioning unit, the control method comprising:

[0015] Obtain a preset first switching pressure and a second switching pressure, wherein the second switching pressure is greater than the first switching pressure, and obtain the refrigerant pressure at the outlet of the first condenser at the current outdoor temperature;

[0016] If the refrigerant pressure is less than the first switching pressure, then shut down the indoor heat exchange system, open the first electrically controlled valve, and close the second electrically controlled valve.

[0017] If the refrigerant pressure is greater than or equal to the first switching pressure and less than or equal to the second switching pressure, then the unit load rate and the preset target load rate of the corresponding indoor unit are obtained. If the unit load rate is greater than the target load rate, then the indoor heat exchange system, the first solenoid valve, and the second solenoid valve are turned on. If the unit load rate is less than or equal to the target load rate, then the indoor heat exchange system is turned off, the first solenoid valve is turned on, and the second solenoid valve is turned off.

[0018] If the refrigerant pressure is greater than the second switching pressure, then the indoor heat exchange system is turned on, the first electrically controlled valve is turned off, and the second electrically controlled valve is turned on.

[0019] Preferably, the steps of turning on the indoor heat exchange system, turning on the first electrically controlled valve and the second electrically controlled valve include:

[0020] The first electrically controlled valve maintains its maximum opening, the second electrically controlled valve performs PID regulation based on the pressure of the second condenser of the indoor heat exchange system, and the compressor of the indoor heat exchange system performs PID calculation based on the corresponding preset indoor temperature and the corresponding actual indoor temperature, and adjusts the operating frequency of the compressor through the PID value.

[0021] Preferably, the steps of turning on the indoor heat exchange system, closing the first electrically controlled valve, and turning on the second electrically controlled valve include:

[0022] The second electronically controlled valve is PID-regulated according to the pressure of the second condenser of the indoor heat exchange system. The compressor of the indoor heat exchange system is PID-calculated according to the corresponding preset indoor temperature and the corresponding actual indoor temperature, and the operating frequency of the compressor is adjusted by the PID value.

[0023] Preferably, the steps following the activation of the indoor heat exchange system, closure of the first electrically controlled valve, and activation of the second electrically controlled valve include:

[0024] The unit load rate and the preset target load rate are obtained in the corresponding room. When the unit load rate is less than or equal to the target load rate, the indoor heat exchange system is shut down, the first electrically controlled valve is opened, and the second electrically controlled valve is closed.

[0025] Preferably, the steps of shutting down the indoor heat exchange system and opening the first electrically controlled valve include:

[0026] PID calculations are performed based on the corresponding preset indoor temperature and the corresponding actual indoor temperature, and the opening degree of the first solenoid valve is adjusted by the PID value.

[0027] Preferably, a preset third switching pressure is obtained, wherein the third switching pressure is less than the second switching pressure. It is then determined whether the refrigerant pressure is less than the third switching pressure. If so, only the outdoor fan corresponding to the first condenser is turned on; otherwise, both the outdoor fan and the spray device are turned on simultaneously.

[0028] Preferably, the rotational speed of the outdoor fan or the spray volume of the spray device is PID-regulated according to the refrigerant pressure.

[0029] Compared with the prior art, the technical solution provided in this application has at least the following beneficial effects:

[0030] The composite air conditioning unit of this application includes an outdoor heat exchange system and an indoor heat exchange system. The opening and closing of the indoor heat exchange system is controlled according to the refrigerant pressure at the outlet of the first condenser of the outdoor heat exchange system. Simultaneously, the opening and closing of the first and second electrically controlled valves are controlled, thereby enabling the air conditioning unit to operate in different cooling modes. The refrigerant pressure reflects the outdoor temperature; the higher the outdoor temperature, the greater the refrigerant pressure. This allows the air conditioning unit to adjust the corresponding cooling mode according to different outdoor conditions. In each cooling mode, it can fully utilize the outdoor natural cold source, ensuring sufficient heat exchange between the first condenser in the outdoor heat exchange system and the outdoor natural cold source. This allows the refrigerant in the outdoor heat exchange system to provide a cooling source for the indoor machine room or the indoor heat exchange system, thus maximizing the utilization of the outdoor natural cold source.

[0031] Furthermore, in different cooling modes of the air conditioning unit, at least one of the first evaporator and the second evaporator provides cooling capacity to the room. The opening degree of the first electronically controlled valve or the operating frequency of the compressor of the indoor heat exchange system can be PID-regulated according to the preset indoor temperature and the actual indoor temperature. The opening degree of the second electronically controlled valve can also be PID-regulated according to the condensing pressure of the indoor heat exchange system, thereby precisely controlling the indoor air outlet temperature of the air conditioning unit to ensure the cooling efficiency of the air conditioning unit. Attached Figure Description

[0032] 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.

[0033] Figure 1 is a schematic diagram of the principle of the composite air conditioning unit provided in the embodiment of this application;

[0034] Figure 2 is a diagram of the refrigerant flow direction of the composite air conditioning unit provided in the embodiment of this application in heat pipe mode;

[0035] Figure 3 is a diagram of the refrigerant flow in the pre-cooling mode of the composite air conditioning unit provided in the embodiment of this application;

[0036] Figure 4 is a diagram of the refrigerant flow in compressor mode for the composite air conditioning unit provided in the embodiment of this application.

[0037] In the diagram: 1-Main circuit; 2-First condenser; 3-Liquid receiver; 4-Pressure pump; 5-Branch circuit; 6-First solenoid valve; 7-First evaporator; 8-Second evaporator; 9-Compressor; 10-Second condenser; 11-Second solenoid valve; 12-Throttling element. 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] Referring to Figure 1, this embodiment provides a composite air conditioning unit, which includes an outdoor heat exchange system and an indoor heat exchange system. The indoor heat exchange system can be configured in the area of ​​the computer room that generates heat. Depending on the actual cooling needs and the number of heat-generating areas, several indoor heat exchange systems can be configured, so that the indoor heat exchange system can accurately cool the heat-generating areas.

[0042] The outdoor heat exchange system includes a main circuit 1 located outdoors. Refrigerant circulates in the main circuit 1. A first condenser 2 is installed on the main circuit 1 to exchange heat between the refrigerant and the external environment. That is, when the refrigerant in the main circuit 1 passes through the first condenser 2, it can exchange heat with the outdoor natural cold source through the first condenser 2, thereby dissipating the heat of the refrigerant to the outdoor environment, while the temperature of the refrigerant itself decreases.

[0043] In addition, several branch lines 5 corresponding to the indoor heat exchange system are provided on the main circuit 1. Since the indoor heat exchange is located inside the machine room, the corresponding branch lines 5 should also be located inside the machine room. It should be noted that as a branch line 5 of the main circuit 1, the two ends of the branch line 5 are connected in series in the main circuit 1. Therefore, the refrigerant in the main circuit 1 can enter the branch line 5 and return to the main circuit 1 when the branch line 5 is open, thereby realizing the circulation of refrigerant in the outdoor heat exchange system. The indoor heat exchange system includes a second condenser 10. Each set of indoor heat exchange systems corresponds to at least two branch lines 5. Referring to Figure 1, in the two branch lines 5, a first electrically controlled valve 6 and a first evaporator 7 are connected in series on one branch line 5, and a second electrically controlled valve 11 is provided on the other branch line 5. The refrigerant in the branch line 5 with the second electrically controlled valve 11 can exchange heat with the second condenser 10, thereby removing the heat released by the second condenser 10, reducing the condensing pressure (temperature) of the second condenser 10, and thus ensuring the cooling efficiency of the indoor heat exchange system.

[0044] It should be noted that the first solenoid valve 6 and the second solenoid valve 11 are mainly used to control the on / off state of the corresponding branch 5, and to adjust the refrigerant flow rate in the corresponding branch 5 by controlling the opening degree of the first solenoid valve 6 and the second solenoid valve 11. Therefore, the first solenoid valve 6 and the second solenoid valve 11 can be electronic expansion valves, solenoid valves or electric ball valves, that is, the first solenoid valve 6 and the second solenoid valve 11 are both solenoid valves with adjustable opening degree, thereby accurately controlling the refrigerant flow rate in the corresponding branch 5.

[0045] In some embodiments, the indoor heat exchange system further includes a compressor 9, a second evaporator 8, and a throttling element 12. Referring to Figures 1-4, the compressor 9, second condenser 10, second evaporator 8, and throttling element 12 are connected to form a refrigerant circulation loop for the indoor heat exchange system. The throttling element 12 can be an electronic expansion valve. When the indoor heat exchange system is running (compressor mode), the second evaporator 8 can supply air to the machine room, thereby reducing the temperature inside the machine room. It should be noted that the indoor heat exchange system and the outdoor heat exchange system are two independent heat exchange systems. The refrigerant within each system circulates only within its corresponding heat exchange system and does not cross-flow. However, under certain operating conditions, the refrigerant in the outdoor heat exchange system will exchange heat with the refrigerant in the indoor heat exchange system in the second condenser 10, thereby removing heat from the refrigerant in the second condenser 10.

[0046] In some embodiments, both the first evaporator 7 and the second evaporator 8 are located indoors, i.e., in the machine room, so that when the air conditioning unit is in different cooling modes, at least one of the first evaporator 7 and the second evaporator 8 provides cooling capacity to the room.

[0047] Furthermore, the first evaporator 7 and the second evaporator 8 can be arranged adjacent to each other, that is, the first evaporator 7 and the second evaporator 8 are close to each other and connected in series in the airflow direction, so that the cooling capacity generated by the first evaporator 7 and / or the second evaporator 8 can be delivered into the room by a single fan.

[0048] It should be noted that since the indoor heat exchange system can be set up in multiple groups, and these groups are relatively independent, each group of indoor heat exchange systems can be controlled separately according to the actual cooling demand of different locations or computer rooms, thus avoiding the situation where the cooling capacity is too large or too small due to the synchronous operation of multiple indoor heat exchange systems.

[0049] Please refer to Figure 1. The first condenser 2 in this application is an evaporative condenser. The heat exchange efficiency of the evaporative condenser is higher than that of the dry cooler and the closed cooling tower. The evaporative condenser can directly transfer heat with the main circuit 1, which can further improve the heat exchange efficiency. In cold winter regions, there is no need to add antifreeze and there is no need to worry about the coil freezing and cracking.

[0050] An evaporative condenser typically includes a heat exchange coil connected to the main circuit 1. The refrigerant in the main circuit 1 enters the heat exchange coil. An external fan is installed on one side of the heat exchange coil; the rotation of the external fan increases the airflow rate around the heat exchange coil, thereby improving the heat exchange efficiency between the refrigerant inside the coil and the external environment. Simultaneously, the evaporative condenser also includes a spray device that sprays water onto the heat exchange coil. This spray device, powered by a circulating pump, continuously sprays water onto the heat exchange coil, further enhancing the heat exchange effect beyond what the external fan provides. Furthermore, a temperature and / or pressure sensor is installed at the outlet of the heat exchange coil to detect the refrigerant temperature and / or pressure at the evaporative condenser outlet. The outlet refrigerant temperature or pressure reflects the outdoor temperature; the higher the outdoor temperature, the higher the outlet refrigerant temperature or pressure, and vice versa.

[0051] In some embodiments, the first condenser 2 may also be one or more tube-fin condensers, etc., which will not be described in detail here. As long as heat exchange between the refrigerant in the main circuit 1 and the external natural cold source can be achieved, they all fall within the protection scope of this application.

[0052] The outdoor heat exchange system of this application also includes a pump cabinet installed on the main circuit 1. The pump cabinet can be used for condensation and transfer of the refrigeration unit. Specifically, it includes a liquid storage tank 3 and a pressure pump 4. The pressure pump 4 provides the power to drive the refrigerant to flow in the main circuit 1 and branch circuits 5. The liquid storage tank 3 stores the refrigerant to ensure sufficient refrigerant flow in the main circuit 1. When the liquid storage tank 3 is connected upstream of the pressure pump 4, it can also protect the pressure pump 4. To ensure the circulation power of the refrigerant in the main circuit 1, at least two pressure pumps 4 can be installed, connected in parallel and located at the liquid outlet of the liquid storage tank 3. In addition, control valves, pressure and temperature sensors, check valves, etc., can be installed according to actual conditions to meet the refrigerant flow requirements.

[0053] Considering that the indoor heat exchange system is located in the machine room, it should maintain a certain degree of compactness to avoid occupying additional indoor space. Therefore, the second condenser 10 can be configured as a fluorinated-fluorinated plate heat exchanger, with both the outdoor and indoor heat exchange systems using fluorinated refrigerant. The fluorinated-fluorinated plate heat exchanger replaces the traditional water-fluorinated plate heat exchanger, achieving efficient heat exchange with the refrigerant in the outdoor system while effectively avoiding scaling problems and potential leaks in the machine room. Furthermore, using fluorine instead of water avoids the risk of coil freezing and cracking during cold seasons. Of course, the indoor second condenser 10 can also be a shell-and-tube heat exchanger or other different types of heat exchangers, each with different dimensions and heat exchange efficiencies.

[0054] This application also provides a control method applicable to the aforementioned combined air conditioning unit. This application uses a single indoor heat exchange system as an example for detailed description. If there are multiple indoor heat exchange systems, since each indoor heat exchange system is independent, the control method for other multiple indoor heat exchange systems can be referenced to that of a single indoor heat exchange system, which will not be elaborated further here. The control method includes:

[0055] The system acquires preset first and second switching pressures, with the second switching pressure being greater than the first. It also acquires the refrigerant pressure at the outlet of the first condenser 2 under the current outdoor temperature. The first and second switching pressures are manually set values, which can be determined through multiple experiments based on the actual conditions of the computer room. Alternatively, switching pressure can be replaced by switching temperature. In this case, the refrigerant temperature at the outlet of the first condenser 2 under the current outdoor temperature should be acquired, ensuring that the units used for comparison are consistent. Both refrigerant temperature and refrigerant pressure represent the outdoor temperature; that is, the higher the outdoor temperature, the higher the refrigerant temperature or pressure, and vice versa.

[0056] Based on the above, if the refrigerant pressure at the outlet of the first condenser 2 is less than the first switching pressure, then the indoor heat exchange system is shut down (compressor 9 is shut down), the first solenoid valve 6 is opened, and the second solenoid valve 11 is closed. This indicates that the outdoor temperature is low, the first condenser 2 has a good heat exchange effect, and the refrigerant pressure at the outlet of the first condenser 2 is low. The heat exchange between the first condenser 2 and the outdoor natural cold source can meet the cooling demand of the computer room. At this time, the air conditioning unit operates in heat pipe mode. Please refer to Figure 2. The refrigerant in the outdoor heat exchange system absorbs heat through the first evaporator 7, and the cooling capacity generated by the first evaporator 7 is discharged into the room, which can meet the cooling demand of the room. If not, proceed to the next step. It should be noted that heat pipe mode refers to the mode in which the outdoor heat exchange system achieves refrigerant circulation and heat exchange without the installation of a compressor.

[0057] If the refrigerant pressure at the outlet of the first condenser 2 is greater than or equal to the first switching pressure and less than or equal to the second switching pressure, the air conditioning unit operates in mixed mode. At the same time, the corresponding indoor unit load rate and the preset target load rate are obtained. This indicates that the outdoor temperature is higher than in heat pipe mode, the refrigerant pressure at the outlet of the first condenser 2 is higher, and the heat exchange efficiency of the first condenser 2 is reduced. Therefore, it is necessary to obtain the corresponding indoor unit load rate and the preset target load rate. The unit load rate actually represents the indoor cooling demand, and the corresponding target load rate should also be based on the unit load rate. The target load rate value is obtained through multiple tests. If the unit load rate is greater than the target load rate, it indicates that the indoor cooling demand is higher. At this time, the indoor heat exchange system can be turned on, and the first electric control valve 6 and the second electric control valve 11 can be turned on. Please refer to Figure 3. At this time, the air conditioning unit operates in pre-cooling mode. Part of the refrigerant in the outdoor heat exchange system can exchange heat with the second condenser 10, and the other part can cooperate with the first evaporator 7 to provide cooling capacity to the computer room. As can be seen, in this pre-cooling mode, the second evaporator 8 of the indoor heat exchange system can provide cooling capacity to the computer room, and the first evaporator 7 can also provide cooling capacity to the computer room. At the same time, the refrigerant of the outdoor heat exchange system can also exchange heat with the second condenser 10 to reduce the condensing pressure of the second condenser 10.

[0058] If the unit load rate is less than or equal to the target load rate, it indicates that the indoor cooling demand is low. In this case, the indoor heat exchange system is shut down, the first electric control valve 6 is opened, and the second electric control valve 11 is closed. At this time, the air conditioning unit still operates in the heat pipe mode described above.

[0059] If the refrigerant pressure at the outlet of the first condenser 2 is greater than the second switching pressure, it indicates that the outdoor temperature is rising further, and the heat exchange efficiency of the first condenser 2 is decreasing further. The unit will then operate in compressor mode. Referring to Figure 4, the indoor heat exchange system can be turned on, the first solenoid valve 6 can be turned off, and the second solenoid valve 11 can be turned on. At this time, the refrigerant in the outdoor heat exchange system is only used for heat exchange with the second condenser 10 of the indoor heat exchange system, thereby further reducing the condensing pressure of the second condenser 10. The indoor heat exchange system then provides cooling capacity solely to the machine room. Based on the heat exchange between the refrigerant in the outdoor heat exchange system and the second condenser 10, the heat exchange efficiency of the indoor heat exchange system is ensured, thus fully utilizing the outdoor natural cold source for indoor cooling.

[0060] It should be noted that the control method of this application can also be implemented according to certain steps, specifically:

[0061] After obtaining the preset first switching pressure, second switching pressure, and refrigerant pressure at the outlet of the first condenser 2, first determine whether the refrigerant pressure is less than the first switching pressure. If so, shut down the indoor heat exchange system, open the first solenoid valve 6, and close the second solenoid valve 11; otherwise, proceed to the next step.

[0062] Determine if the refrigerant pressure is less than or equal to the second switching pressure. If so, obtain the corresponding indoor unit load pressure and the preset third switching pressure. If the unit load pressure is greater than the third switching pressure, open the indoor heat exchange system, open the first solenoid valve 6 and the second solenoid valve 11. If the unit load pressure is less than or equal to the third switching pressure, close the indoor heat exchange system, open the first solenoid valve 6 and close the second solenoid valve 11. If not, open the indoor heat exchange system, close the first solenoid valve 6 and open the second solenoid valve 11.

[0063] The control method of this embodiment further includes the following steps when starting the indoor heat exchange system and opening the first solenoid valve 6 and the second solenoid valve 11:

[0064] The first solenoid valve 6 maintains its maximum opening. The second solenoid valve 11 performs PID regulation based on the pressure of the second condenser 10 in the indoor heat exchange system. The compressor 9 in the indoor heat exchange system performs PID calculation based on the corresponding preset indoor temperature and the corresponding actual indoor temperature. The operating frequency of the compressor 9 is adjusted through the PID value, thereby adjusting the opening of the second solenoid valve 11 according to the pressure of the second condenser 10 to regulate the condensing pressure of the second condenser 10 in real time. At the same time, while ensuring the condensing pressure of the second condenser 10, the operating frequency of the compressor 9 is adjusted according to the PID values ​​of the preset indoor temperature and the actual temperature, thereby ensuring that the indoor heat exchange system has a high energy efficiency ratio.

[0065] The steps following starting the indoor heat exchange system, closing the first electrically controlled valve 6, and opening the second electrically controlled valve 11 include:

[0066] The system obtains the corresponding indoor unit load rate and the preset target load rate. When the unit load rate is less than or equal to the target load rate, the indoor heat exchange system is shut down, the first solenoid valve 6 is opened, and the second solenoid valve 11 is closed. That is, as the air conditioning unit continues to run in compressor mode, the indoor temperature will gradually decrease, causing the corresponding unit load rate to gradually decrease until the unit load rate is less than or equal to the target load rate. At this point, the air conditioning unit can switch from compressor mode to heat pipe mode, thereby reducing the energy consumption of starting compressor 9 while meeting the cooling energy efficiency requirements, and thus reducing the power consumption of the data center.

[0067] In addition, when the air conditioning unit is operating in heat pipe mode or switching from other modes to heat pipe mode, i.e., shutting down the indoor heat exchange system and opening the first electrically controlled valve 6, this step also includes:

[0068] Based on the corresponding preset indoor temperature and the corresponding actual indoor temperature, PID calculation is performed, and the opening degree of the first solenoid valve 6 is adjusted by the PID value. In this way, the opening degree of the first solenoid valve 6 is controlled according to the indoor cooling demand to meet the indoor cooling demand.

[0069] It should be noted that the control method of this application also includes:

[0070] Obtain the preset third switching pressure. If the third switching pressure is less than the second switching pressure, determine whether the refrigerant pressure is less than the third switching pressure. If yes, only the outdoor fan corresponding to the first condenser 2 is turned on. If no, it means that the heat exchange effect of the first condenser 2 is very poor. Therefore, it is necessary to turn on the outdoor fan and the spray device at the same time to improve the heat exchange effect of the first condenser 2 and ensure the heat exchange effect of the refrigerant in the outdoor heat exchange system.

[0071] Meanwhile, the speed of the outdoor fan or the spray water volume of the spray device are adjusted by PID according to the refrigerant pressure, so as to automatically adjust the speed of the outdoor fan and the spray water volume of the spray device according to the outdoor temperature to ensure the heat exchange efficiency of the outdoor heat exchange system.

[0072] In summary, the composite air conditioning unit of this application includes an outdoor heat exchange system and an indoor heat exchange system. The opening and closing of the indoor heat exchange system is controlled according to the different refrigerant pressures at the outlet of the first condenser 2 of the outdoor heat exchange system. Simultaneously, the opening and closing of the first solenoid valve 6 and the second solenoid valve 11 are controlled, thereby enabling the air conditioning unit to operate in different cooling modes. The refrigerant pressure reflects the outdoor temperature; the higher the outdoor temperature, the greater the refrigerant pressure. This allows the air conditioning unit to adjust the corresponding cooling mode according to different outdoor conditions. In each cooling mode, the outdoor natural cold source can be fully utilized, allowing the first condenser 2 in the outdoor heat exchange system to fully exchange heat with the outdoor natural cold source. This enables the refrigerant in the outdoor heat exchange system to provide a cold source for the indoor machine room or the indoor heat exchange system, achieving the goal of maximizing the utilization of the outdoor natural cold source.

[0073] Furthermore, under different cooling modes of the air conditioning unit, the opening degree of the first electronically controlled valve 6 or the operating frequency of the compressor 9 of the indoor heat exchange system can be PID-regulated according to the preset indoor temperature and the actual indoor temperature, and the opening degree of the second electronically controlled valve 11 can be PID-regulated according to the condensing pressure of the indoor heat exchange system, thereby precisely controlling the indoor side outlet air temperature of the air conditioning unit to ensure the cooling efficiency of the air conditioning unit.

[0074] 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.

[0075] 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 hybrid air conditioning unit, comprising: The composite air conditioning unit comprises an outdoor heat exchange system and an indoor heat exchange system, the outdoor heat exchange system comprises a main circuit (1) for refrigerant flow, the main circuit (1) is provided with a first condenser (2) and a pressure pump (4), the first condenser (2) exchanges heat with the external environment, and the main circuit (1) is provided with a plurality of branch circuits (5) corresponding to the indoor heat exchange system; The indoor heat exchange system comprises a compressor (9), a second condenser (10), a throttling element (12) and a second evaporator (8), which are connected to form a refrigerant circulation circuit of the indoor heat exchange system, the indoor heat exchange system is at least one group, and each group of the indoor heat exchange system corresponds to at least two branch circuits (5), in the two branch circuits (5), one branch circuit (5) is provided with a first electric control valve (6) and a first evaporator (7), and the other branch circuit (5) is provided with a second electric control valve (11) and exchanges heat with the second condenser (10) to take away the refrigerant heat in the indoor heat exchange system; The first evaporator (7) and the second evaporator (8) are both arranged in the room, at least one of the first evaporator (7) and the second evaporator (8) provides cold energy for the room, and the first evaporator (7) and the second evaporator (8) are arranged in series in the air flow direction.

2. The hybrid air conditioning unit of claim 1, wherein, The first condenser (2) is an evaporative condenser, the evaporative condenser comprises a heat exchange coil in communication with the main circuit (1), one side of the heat exchange coil is provided with an external fan, the evaporative condenser further comprises a spraying device for spraying towards the heat exchange coil, and the outlet end of the heat exchange coil is provided with a temperature and / or pressure sensor to detect the outlet refrigerant temperature and / or pressure of the evaporative condenser.

3. The hybrid air conditioning unit of claim 1, wherein The refrigerant of the outdoor heat exchange system and the refrigerant of the indoor heat exchange system are fluorine refrigerants.

4. The hybrid air conditioning unit of claim 1, wherein The outdoor heat exchange system further comprises a liquid storage tank (3) arranged on the main circuit (1), the number of the pressure pump (4) is at least two, and the parallelly connected pressure pumps (4) are arranged at the liquid outlet end of the liquid storage tank (3).

5. The hybrid air conditioning unit of claim 1, wherein The second condenser (10) is a plate heat exchanger for fluorine-fluorine heat exchange.

6. A control method characterized by, The control method is applied to the composite air conditioning unit of any one of claims 1-5, and the control method comprises: obtaining a preset first switching pressure and a second switching pressure, the second switching pressure being greater than the first switching pressure, and obtaining the refrigerant pressure at the outlet of the first condenser (2) under the current outdoor temperature; if the refrigerant pressure is less than the first switching pressure, closing the indoor heat exchange system, opening the first electric control valve (6) and closing the second electric control valve (11); if the refrigerant pressure is greater than or equal to the first switching pressure and less than or equal to the second switching pressure, obtaining the unit load rate of the corresponding indoor and a preset target load, if the unit load rate is greater than the target load rate, opening the indoor heat exchange system, opening the first electric control valve (6) and the second electric control valve (11), if the unit load rate is less than or equal to the target load rate, closing the indoor heat exchange system, opening the first electric control valve (6) and closing second electric control valve (11); If the refrigerant pressure is greater than the second switching pressure, the indoor heat exchange system is opened, the first electric control valve (6) is closed, and the second electric control valve (11) is opened.

7. The control method according to claim 6, characterized by The step of opening the indoor heat exchange system, opening the first electric control valve (6) and the second electric control valve (11) comprises: The first electric control valve (6) keeps maximum opening, the second electric control valve (11) is PID adjusted according to the second condenser (10) pressure of the indoor heat exchange system, and the compressor (9) of the indoor heat exchange system is PID calculated according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and the running frequency of the compressor (9) is adjusted through the PID value.

8. The control method according to claim 6, characterized by The step of opening the indoor heat exchange system, closing the first electric control valve (6) and opening the second electric control valve (11) comprises: The second electric control valve (11) is PID adjusted according to the second condenser (10) of the indoor heat exchange system, and the compressor (9) of the indoor heat exchange system carries out PID calculation according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and the running frequency of compressor (9) is adjusted through the PID value.

9. The control method according to claim 6 or 8, characterized by, The step after opening the indoor heat exchange system, closing the first electric control valve (6) and opening the first electric control valve (11) comprises: The unit load rate of the corresponding indoor and the preset target load rate are obtained, and when the unit load rate is less than or equal to the target load rate, the indoor heat exchange system is closed, the first electric control valve (6) is opened, and the second electric control valve (11) is closed.

10. The control method according to claim 9, characterized by The step of closing the indoor heat exchange system and opening the first electric control valve (6) comprises: PID calculation is carried out according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and the opening of the first electric control valve (6) is adjusted through the PID value.

11. The control method according to claim 6, characterized by, A preset third switching pressure is obtained, the third switching pressure is less than the second switching pressure, it is judged whether the refrigerant pressure is less than the third switching pressure, if yes, only the outdoor fan corresponding to the first condenser (2) is opened, and if no, the outdoor fan and the spraying device are opened at the same time.

12. The control method according to claim 11, characterized by, The rotation speed of the outdoor fan or the spraying water amount of the spraying device is PID adjusted according to the refrigerant pressure.

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