Combined type air conditioning unit and control method

Abstract

The invention discloses a combined type air conditioning unit and a control method, and relates to the technical field of machine room air conditioners, the combined type air conditioning unit comprises an outdoor heat exchange system and an indoor heat exchange system, the outdoor heat exchange system comprises a main loop, a first condenser and a pressure pump, and the main loop is provided with a plurality of branches corresponding to the indoor heat exchange system; the indoor heat exchange system comprises a compressor, a second condenser, a throttling element and a second evaporator, one set of indoor heat exchange system at least corresponds to two branches, one branch is connected with a first electric control valve and a first evaporator in series, and the other branch is provided with a second electric control valve and exchanges heat with the second condenser. Therefore, refrigerant heat in the indoor heat exchange system is taken away. Wherein the first evaporator and the second evaporator are both arranged indoors, at least one of the first evaporator and the second evaporator provides cooling capacity for the indoor space, and the first evaporator and the second evaporator are arranged in series in the airflow direction. Different refrigeration modes can be operated according to different outdoor working conditions, and outdoor natural cold sources are utilized to the maximum extent.

Description

Technical Field

[0001] The present application relates to the technical field of computer room air conditioning, and in particular to a composite air conditioning unit and a control method thereof. Background Art

[0002] Most of the existing large data center computer rooms use indirect evaporative cooling units, fluorine pump multi-split units, etc., while traditional room-level and row-to-row air conditioners are mostly used in small computer rooms, distribution rooms and battery rooms due to their low energy efficiency.

[0003] In the process of implementing the present invention, the inventors found that the prior art has at least the following problems:

[0004] Existing air-conditioning units are unable to automatically adjust their operating modes according to different outdoor working conditions, which results in the air-conditioning units being unable to fully utilize outdoor natural cold sources, resulting in low cooling efficiency of the air-conditioning units and increased power consumption of the data center.

[0005] Therefore, in response to the above technical problems, how to maximize the use of outdoor natural cooling sources while ensuring the refrigeration efficiency of the air-conditioning unit is a technical problem that technical personnel in this field need to solve. Summary of the invention

[0006] The purpose of the present application is to provide a composite air-conditioning unit and a control method, which can operate different cooling modes according to different outdoor working conditions and make maximum use of outdoor natural cooling sources.

[0007] To achieve the above-mentioned purpose, the present application provides a composite air-conditioning unit, including an outdoor heat exchange system and an indoor heat exchange system, wherein the outdoor heat exchange system includes a main circuit for the flow of refrigerant, a first condenser and a pressure pump are provided on the main circuit, the first condenser exchanges heat with the external environment, and a plurality of branches corresponding to the indoor heat exchange system are provided on the main circuit;

[0008] 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 group, and each group of the indoor heat exchange system corresponds to at least two branches. Among the two branches, one branch is connected in series with a first electric control valve and a first evaporator, and the other branch is provided with a second electric control valve and heat exchanges with the second condenser to take away the heat of the refrigerant in the indoor heat exchange system.

[0009] Wherein, the first evaporator and the second evaporator are both arranged indoors, at least one of the first evaporator and the second evaporator provides cooling for the indoors, and the first evaporator and the second evaporator are arranged in series in the air flow direction.

[0010] Preferably, the first condenser is an evaporative condenser, which includes a heat exchange coil connected to the main circuit, an external fan is correspondingly provided on one side of the heat exchange coil, and the evaporative condenser also includes a spray device for spraying toward the heat exchange coil. The outlet end of the heat exchange coil is provided with a temperature and / or pressure sensor to detect the refrigerant temperature and / or pressure at the outlet of the evaporative condenser.

[0011] Preferably, the refrigerant of the outdoor heat exchange system and the refrigerant of the indoor heat exchange system are fluorine refrigerants.

[0012] Preferably, the outdoor heat exchange system further comprises a liquid storage tank arranged on the main circuit, the number of the pressure pumps is at least two, and the pressure pumps are connected in parallel and arranged at the liquid outlet end of the liquid storage tank.

[0013] A control method is applied to the above-mentioned composite air-conditioning unit, and the control method comprises:

[0014] Obtaining a preset first switching pressure and a second switching pressure, where the second switching pressure is greater than the first switching pressure, and obtaining the refrigerant pressure at the outlet of the first condenser at the current outdoor temperature;

[0015] If the refrigerant pressure is less than the first switching pressure, the indoor heat exchange system is closed, the first electric control valve is opened, and the second electric control valve is closed;

[0016] If the refrigerant pressure is greater than or equal to the first switching pressure and less than or equal to the second switching pressure, the unit load rate and the preset target load rate in the corresponding room are obtained; if the unit load rate is greater than the target load rate, the indoor heat exchange system is turned on, and the first electric control valve and the second electric control valve are turned on; if the unit load rate is less than or equal to the target load rate, the indoor heat exchange system is turned off, the first electric control valve is turned on, and the second electric control valve is turned off;

[0017] If the refrigerant pressure is greater than the second switching pressure, the indoor heat exchange system is turned on, the first electrically controlled valve is closed, and the second electrically controlled valve is turned on.

[0018] Preferably, the step of starting the indoor heat exchange system and opening the first electrically controlled valve and the second electrically controlled valve comprises:

[0019] The first electrically controlled valve maintains a maximum opening, the second electrically controlled valve performs PID adjustment according to the second condenser pressure of the indoor heat exchange system, the compressor of the indoor heat exchange system performs PID calculation according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and adjusts the operating frequency of the compressor through the PID value.

[0020] Preferably, the steps of opening the indoor heat exchange system, closing the first electrically controlled valve, and opening the second electrically controlled valve include:

[0021] The second electrically controlled valve performs PID adjustment according to the second condenser pressure of the indoor heat exchange system, and the compressor of the indoor heat exchange system performs PID calculation according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and adjusts the operating frequency of the compressor through the PID value.

[0022] Preferably, the steps after starting the indoor heat exchange system, closing the first electrically controlled valve, and opening the second electrically controlled valve include:

[0023] The unit load rate in the corresponding room and the preset target load rate are obtained. When the unit load rate is less than or equal to the target load rate, the indoor heat exchange system is closed, the first electrically controlled valve is opened, and the second electrically controlled valve is closed.

[0024] Preferably, the step of closing the indoor heat exchange system and opening the first electrically controlled valve includes:

[0025] PID calculation is performed according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and the opening of the first electronically controlled valve is adjusted according to the PID value.

[0026] Preferably, a preset third switching pressure is obtained, and the third switching pressure is less than the second switching pressure. It is determined whether the refrigerant pressure is less than the third switching pressure. If so, only the external fan corresponding to the first condenser is turned on; if not, the external fan and the spray device are turned on at the same time.

[0027] Preferably, the rotation speed of the outdoor fan or the spraying water volume of the spraying device is PID-regulated according to the refrigerant pressure.

[0028] Compared with the prior art, the technical solution provided by this application has at least the following beneficial effects:

[0029] The composite air-conditioning unit of the present application includes an outdoor heat exchange system and an indoor heat exchange system. According to the different refrigerant pressures at the outlet of the first condenser of the outdoor heat exchange system, the opening and closing of the indoor heat exchange system is controlled, and the opening and closing of the first electric-controlled valve and the second electric-controlled valve are controlled at the same time, so that the air-conditioning unit operates in different cooling modes; and the refrigerant pressure reflects the outdoor temperature conditions. The higher the outdoor temperature, the greater the refrigerant pressure, so that the air-conditioning unit adjusts the corresponding cooling mode according to the different outdoor working conditions, and in each cooling mode, it can make full use of the outdoor natural cold source, so that the first condenser in the outdoor heat exchange system can fully exchange heat with the outdoor natural cold source, and then the refrigerant in the outdoor heat exchange system can provide a cold source for the indoor machine room or the indoor heat exchange system, so as to achieve the purpose of maximizing the utilization of the outdoor natural cold source.

[0030] And in different refrigeration modes of the air-conditioning unit, at least one of the first evaporator and the second evaporator provides cooling for the indoor room, and can perform PID adjustment on the opening of the first electric control valve or the compressor operating frequency of the indoor heat exchange system according to the indoor preset temperature and the actual indoor temperature, and perform PID adjustment on the opening of the second electric control valve according to the condensing pressure of the indoor heat exchange system, so as to accurately control the indoor side air outlet temperature of the air-conditioning unit to ensure the refrigeration energy efficiency of the air-conditioning unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0032] Figure 1 A schematic diagram of the principle of a composite air-conditioning unit provided in an embodiment of the present application;

[0033] Figure 2 A refrigerant flow diagram of a composite air-conditioning unit in a heat pipe mode provided in an embodiment of the present application;

[0034] Figure 3 A refrigerant flow diagram of the composite air-conditioning unit in the pre-cooling mode provided in an embodiment of the present application;

[0035] Figure 4 This is a refrigerant flow diagram of the combined air-conditioning unit provided in the embodiment of the present application in the compressor mode.

[0036] In the figure: 1-main circuit; 2-first condenser; 3-liquid storage tank; 4-pressure pump; 5-branch; 6-first electric control valve; 7-first evaporator; 8-second evaporator; 9-compressor; 10-second condenser; 11-second electric control valve; 12-throttling element. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] It should be noted that in this embodiment, the directions or positional relationships indicated by "upper", "lower", "front", "back", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0039] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0040] Please refer to Figure 1 In this embodiment, a composite air-conditioning unit is provided, which includes an outdoor heat exchange system and an indoor heat exchange system. The indoor heat exchange system can be configured in an area with heat generation in the computer room, and according to actual cooling needs and different numbers of heat generation areas, several indoor heat exchange systems can be configured, so that the indoor heat exchange system can accurately cool the heat generation area.

[0041] The outdoor heat exchange system includes a main circuit 1 partially located outdoors, in which refrigerant circulates, and a first condenser 2 is provided on the main circuit 1 for exchanging 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, and at the same time the temperature of the refrigerant itself is reduced.

[0042] In addition, several branches 5 corresponding to the indoor heat exchange system are provided on the main circuit 1. Since the indoor heat exchange is arranged inside the machine room, the corresponding branches 5 should also be arranged in the machine room. It should be pointed out that as the branch 5 of the main circuit 1, both ends of the branch 5 are connected in series in the main circuit 1. Therefore, the refrigerant in the main circuit 1 can enter the branch 5 and flow back to the main circuit 1 when the branch 5 is turned on, thereby realizing the circulation of the refrigerant in the outdoor heat exchange system. Among them, the indoor heat exchange system includes a second condenser 10. A group of indoor heat exchange systems corresponds to at least two branches 5. Please refer to Figure 1 In the two branches 5, a first electrically controlled valve 6 and a first evaporator 7 are connected in series on one branch 5, and a second electrically controlled valve 11 is provided on the other branch 5, and the refrigerant in the branch 5 provided with the second electrically controlled valve 11 can exchange heat with the second condenser 10, thereby taking away the heat released by the second condenser 10 to reduce the condensation pressure (temperature) of the second condenser 10, thereby ensuring the refrigeration energy efficiency of the indoor heat exchange system.

[0043] It should be pointed out that the first electrically controlled valve 6 and the second electrically controlled valve 11 are mainly used to control the on and off of the corresponding branch 5, and to adjust the flow rate of the refrigerant in the corresponding branch 5 by controlling the opening of the first electrically controlled valve 6 and the second electrically controlled valve 11. Therefore, the first electrically controlled valve 6 and the second electrically controlled valve 11 can be electronic expansion valves, solenoid valves or electric ball valves, that is, the first electrically controlled valve 6 and the second electrically controlled valve 11 are both electrically controlled valves with adjustable opening, so as to accurately control the flow rate of the refrigerant in the corresponding branch 5.

[0044] In some embodiments, the indoor heat exchange system further includes a compressor 9, a second evaporator 8 and a throttling element 12, please refer to Figure 1-4 The compressor 9, the second condenser 10, the second evaporator 8, and the throttling element 12 are connected to form a refrigerant circulation loop of 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 in the machine room. It should be pointed out that the indoor heat exchange system and the outdoor heat exchange system are two independent heat exchange systems. The refrigerants in the two only circulate in the corresponding heat exchange systems and will not produce cross-flow; however, under certain working conditions, the refrigerant in the outdoor heat exchange system will realize heat exchange with the refrigerant in the indoor heat exchange system in the second condenser 10, thereby taking away the heat of the refrigerant in the second condenser 10.

[0045] In some embodiments, the first evaporator 7 and the second evaporator 8 are both located indoors, that is, in a 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 for the room.

[0046] Furthermore, the first evaporator 7 and the second evaporator 8 can be arranged adjacent to each other, that is, the first evaporator 7 is close to the second evaporator 8 and is arranged in series in the airflow direction, so that a fan can be used to deliver the cold energy generated by the first evaporator 7 and / or the second evaporator 8 into the room.

[0047] It should be noted that since the indoor heat exchange system can be set up into multiple groups, and the multiple groups of indoor heat exchange systems are relatively independent, that is, each group of indoor heat exchange systems can be controlled individually according to the actual cooling demand of different locations or computer rooms, avoiding the situation where the synchronous operation of multiple groups of indoor heat exchange systems causes excessive or insufficient cooling capacity.

[0048] Please refer to Figure 1 The first condenser 2 of the present 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 areas in winter, there is no need to add antifreeze and there is no need to worry about coil freezing and cracking.

[0049] The evaporative condenser usually includes a heat exchange coil connected to the main circuit 1. The refrigerant in the main circuit 1 can enter the heat exchange coil. An external fan is correspondingly provided on one side of the heat exchange coil. The rotation of the external fan can increase the air flow rate around the heat exchange coil, thereby improving the heat exchange efficiency between the refrigerant in the heat exchange coil and the external environment. At the same time, the evaporative condenser also includes a spray device for spraying toward the heat exchange coil. The spray device can realize continuous spraying of the heat exchange coil through a circulating pump, thereby further improving the heat exchange effect of the heat exchange coil on the basis of the external fan. In addition, a temperature and / or pressure sensor is provided at the outlet end of the heat exchange coil to detect the outlet refrigerant temperature and / or pressure of the evaporative condenser. The outlet refrigerant temperature or pressure of the evaporative condenser represents the outdoor temperature, that is, the higher the outdoor temperature, the greater the outlet refrigerant temperature or pressure, and vice versa.

[0050] In some embodiments, the first condenser 2 can also be one or more tube-fin condensers, etc., which will not be described in detail here. It is sufficient to ensure that heat exchange can be achieved between the refrigerant in the main circuit 1 and the external natural cooling source, which falls within the protection scope of this application.

[0051] The outdoor heat exchange system of the present application also includes a pump cabinet arranged on the main circuit 1, which can be used for condensation and transmission of the refrigerator; specifically, it includes a liquid storage tank 3 and a pressure pump 4, the pressure pump 4 is used to provide power to drive the refrigerant to flow in the main circuit 1 and the branch 5, the liquid storage tank 3 is used to store the refrigerant to ensure that the main circuit 1 has enough refrigerant flowing in the main circuit 1, and when the liquid storage tank 3 is connected to the upstream of the pressure pump 4, it can also play a role in protecting the pressure pump 4. In order to ensure the circulation power of the refrigerant in the main circuit 1, at least two pressure pumps 4 can be set, and the pressure pumps 4 are arranged at the liquid outlet end of the liquid storage tank 3 after being connected in parallel. In addition, control valves, pressure and temperature sensors, one-way valves, etc. can be set according to actual conditions to meet the flow requirements of the refrigerant.

[0052] Considering that the indoor heat exchange system is located in the machine room, the indoor heat exchange system should maintain a certain degree of compactness to avoid occupying additional indoor space. Here, the second condenser 10 can be set as a fluorine-fluorine heat exchange plate heat exchanger, and the corresponding refrigerant of the outdoor heat exchange system and the refrigerant of the indoor heat exchange system are fluorine refrigerants. The fluorine-fluorine heat exchange plate heat exchanger replaces the traditional water-fluorine plate heat exchanger. On the one hand, it can achieve efficient heat exchange with the refrigerant in the outdoor heat exchange system. On the other hand, it can effectively avoid the scaling problem of the plate exchange and the hidden danger of water leakage in the machine room. At the same time, using fluorine instead of water can avoid the risk of coil freezing and cracking in cold seasons. Of course, the second condenser 10 on the indoor side can also be a shell and tube heat exchanger or other types of heat exchangers. Different heat exchangers have different external dimensions and different heat exchange efficiencies.

[0053] The present application also provides a control method that can be applied to the above-mentioned composite air conditioning unit. The present application takes a group of indoor heat exchange systems as an example for introduction. If there are multiple groups of indoor heat exchange systems, since each group of indoor heat exchange is independent of each other, the control method of the other multiple groups of indoor heat exchange systems can refer to the control method of the group of indoor heat exchange systems, which will not be repeated here. The control method includes:

[0054] Obtain the preset first switching pressure and second switching pressure, the second switching pressure is greater than the first switching pressure, and obtain the refrigerant pressure at the outlet of the first condenser 2 at the current outdoor temperature; wherein, the first switching pressure and the second switching pressure are manually set pressure values, and the switching pressure that meets the requirements can be obtained through multiple tests according to the actual situation of the machine room. Of course, the switching pressure can also be replaced by the switching temperature, and the corresponding refrigerant temperature at the outlet of the first condenser 2 at the current outdoor temperature should be obtained, and it is sufficient to ensure that the units of comparison are consistent. The refrigerant temperature and the refrigerant pressure can both represent the outdoor temperature conditions, that is, the higher the outdoor temperature, the greater the refrigerant temperature or refrigerant pressure becomes, and vice versa;

[0055] On the basis of the above, if the refrigerant pressure at the outlet of the first condenser 2 is less than the first switching pressure, the indoor heat exchange system is turned off (the compressor 9 is turned off), the first electric control valve 6 is opened, and the second electric control valve 11 is closed. At this time, it means 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 small. 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 the heat pipe mode. Please refer to Figure 2 , the refrigerant of the outdoor heat exchange system absorbs heat through the first evaporator 7, and the cold energy generated by the first evaporator 7 is discharged to the room, which can meet the indoor cold energy demand; if not, the next step is executed; it should be pointed out that the heat pipe mode refers to the mode in which the outdoor heat exchange system realizes the circulation of refrigerant and heat exchange without setting a compressor;

[0056] 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 a mixed mode, and at the same time obtains the unit load rate of the corresponding room and the preset target load rate. At this time, it means that the outdoor temperature is higher than that in the heat pipe mode, and the corresponding refrigerant pressure at the outlet of the first condenser 2 increases, and the heat exchange efficiency of the first condenser 2 decreases. Therefore, it is necessary to obtain the unit load rate of the corresponding room 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 as a reference, and the target load rate value is obtained through multiple tests; if the unit load rate is greater than the target load rate, it means that the indoor cooling demand is high. 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 3At this time, the air-conditioning unit runs in the pre-cooling mode, part of the refrigerant of the outdoor heat exchange system can exchange heat with the second condenser 10, and the other part can cooperate with the first evaporator 7, so that the first evaporator 7 provides cooling for the machine room. It can be seen that in this pre-cooling mode, the second evaporator 8 of the indoor heat exchange system can provide cooling for the machine room, and the first evaporator 7 can also provide cooling for the machine 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;

[0057] If the unit load rate is less than or equal to the target load rate, it means that the indoor cooling demand is low, then the indoor heat exchange system is turned off, 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 the above-mentioned heat pipe mode;

[0058] If the refrigerant pressure at the outlet of the first condenser 2 is greater than the second switching pressure, it means that the outdoor temperature rises further, the heat exchange efficiency of the first condenser 2 decreases further, and the unit runs in compressor mode. Please refer to Figure 4 , the indoor heat exchange system can be turned on, the first electric control valve 6 can be closed, and the second electric control valve 11 can be turned on. At this time, the refrigerant of 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 condensation pressure of the second condenser 10. At this time, the indoor heat exchange system alone provides cooling for the machine room, and on the basis of heat exchange between the refrigerant of the outdoor heat exchange system and the second condenser 10, the heat exchange efficiency of the indoor heat exchange system is guaranteed, so that the outdoor natural cold source can be fully utilized to cool the room.

[0059] It should be noted that the control method of the present application can also be controlled according to certain steps, specifically:

[0060] After obtaining the preset first switching pressure, the second switching pressure and the 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, close the indoor heat exchange system, open the first electric control valve 6, and close the second electric control valve 11; if not, execute the next step;

[0061] Determine whether the refrigerant pressure is less than or equal to the second switching pressure. If so, obtain the unit load pressure in the corresponding room 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 electric control valve 6 and the second electric control 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 electric control valve 6, and close the second electric control valve 11; if not, open the indoor heat exchange system, close the first electric control valve 6, and open the second electric control valve 11.

[0062] The control method of this embodiment, when starting the indoor heat exchange system and opening the first electrically controlled valve 6 and the second electrically controlled valve 11, further includes:

[0063] The first electrically-controlled valve 6 maintains the maximum opening, the second electrically-controlled valve 11 performs PID adjustment according to the pressure of the second condenser 10 of the indoor heat exchange system, the compressor 9 of the indoor heat exchange system performs PID calculation according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and adjusts the operating frequency of the compressor 9 through the PID value, thereby adjusting the opening of the second electrically-controlled valve 11 according to the pressure of the second condenser 10 to adjust the condensing pressure of the second condenser 10 in real time; at the same time, on the basis of ensuring the condensing pressure of the second condenser 10, the operating frequency of the compressor 9 is adjusted according to the PID value of the indoor preset temperature and the actual temperature, thereby ensuring that the indoor heat exchange system has a high energy efficiency ratio.

[0064] The steps after starting the indoor heat exchange system, closing the first electrically controlled valve 6, and opening the second electrically controlled valve 11 include:

[0065] The unit load rate in the corresponding room and the preset target load rate are obtained. 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; that is, as the air-conditioning unit continues to operate in the 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. The air-conditioning unit can switch from the compressor mode to the heat pipe mode, thereby reducing the energy consumption of turning on the compressor 9 while meeting the refrigeration energy efficiency, thereby reducing the power consumption of the data center.

[0066] In addition, when the air conditioning unit operates in the heat pipe mode or switches from other modes to the heat pipe mode, the indoor heat exchange system is closed and the first electric control valve 6 is opened. This step also includes:

[0067] PID calculation is performed according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and the opening of the first electrically controlled valve 6 is adjusted by the PID value, so as to control the opening of the first electrically controlled valve 6 according to the indoor cooling demand to meet the indoor cooling demand.

[0068] It should be noted that the control method of the present application also includes:

[0069] Obtain a preset third switching pressure, which is less than the second switching pressure, and determine whether the refrigerant pressure is less than the third switching pressure. If so, only turn on the external fan corresponding to the first condenser 2; if not, it means that the heat exchange effect of the first condenser 2 is very poor, so it is necessary to turn on the external fan and the spray device at the same time to improve the heat exchange effect of the first condenser 2 to ensure the heat exchange effect of the refrigerant in the outdoor heat exchange system.

[0070] At the same time, the speed of the outdoor fan or the spraying water volume of the spraying device is PID-adjusted according to the refrigerant pressure, thereby automatically adjusting the speed of the outdoor fan and the spraying water volume of the spraying device according to the outdoor temperature to ensure the heat exchange efficiency of the outdoor heat exchange system.

[0071] In summary, the composite air-conditioning unit of the present application includes an outdoor heat exchange system and an indoor heat exchange system. According to the different refrigerant pressures at the outlet of the first condenser 2 of the outdoor heat exchange system, the opening and closing of the indoor heat exchange system is controlled, and the opening and closing of the first electric control valve 6 and the second electric control valve 11 are controlled at the same time, so that the air-conditioning unit operates in different cooling modes; and the refrigerant pressure reflects the outdoor temperature conditions. The higher the outdoor temperature, the greater the refrigerant pressure, so that the air-conditioning unit adjusts the corresponding cooling mode according to the different outdoor working conditions, and in each cooling mode, it can make full use of the outdoor natural cold source, so that the first condenser 2 in the outdoor heat exchange system can fully exchange heat with the outdoor natural cold source, and then the refrigerant in the outdoor heat exchange system can provide a cold source for the indoor machine room or the indoor heat exchange system, so as to achieve the purpose of maximizing the utilization of the outdoor natural cold source.

[0072] And in different cooling modes of the air-conditioning unit, the opening of the first electric control valve 6 or the operating frequency of the compressor 9 of the indoor heat exchange system can be PID adjusted according to the indoor preset temperature and the actual indoor temperature, and the opening of the second electric control valve 11 can be PID adjusted according to the condensing pressure of the indoor heat exchange system, so as to accurately control the indoor side air outlet temperature of the air-conditioning unit to ensure the refrigeration energy efficiency of the air-conditioning unit.

[0073] It should be noted that, in this specification, relational terms such as first and second are merely used to distinguish one entity from other entities, but do not necessarily require or imply any actual relationship or order between these entities.

[0074] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the description of the above embodiments is only used to help understand the method and core ideas of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A composite air conditioning unit, characterized in that: It comprises an outdoor heat exchange system and an indoor heat exchange system, the outdoor heat exchange system comprises a main circuit (1) for the flow of refrigerant, 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 branches (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 loop 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 branches (5). Among the two branches (5), one branch (5) is connected in series with a first electric control valve (6) and a first evaporator (7), and the other branch (5) is provided with a second electric control valve (11) and exchanges heat with the second condenser (10) to remove the heat of the refrigerant in the indoor heat exchange system. The first evaporator (7) and the second evaporator (8) are both arranged indoors, at least one of the first evaporator (7) and the second evaporator (8) provides cooling for the room, and the first evaporator (7) and the second evaporator (8) are arranged in series in the airflow direction.

2. The composite air conditioning unit according to claim 1, characterized in that: The first condenser (2) is an evaporative condenser, comprising a heat exchange coil connected to the main circuit (1), an external fan being provided on one side of the heat exchange coil, the evaporative condenser also comprising a spray device for spraying toward the heat exchange coil, and a temperature and / or pressure sensor being 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.

3. The composite air conditioning unit according to claim 1, characterized in that: The refrigerant of the outdoor heat exchange system and the refrigerant of the indoor heat exchange system are fluorine refrigerants.

4. The compound air conditioning unit according to claim 1, characterized in that: The outdoor heat exchange system further comprises a liquid storage tank (3) arranged on the main circuit (1), the number of the pressure pumps (4) is at least two, and the pressure pumps (4) are arranged in parallel at the liquid outlet end of the liquid storage tank (3).

5. The composite air conditioning unit according to claim 1, characterized in that: The second condenser (10) is a plate heat exchanger for fluorine-fluorine heat exchange.

6. A control method, characterized in that: Applied to the composite air conditioning unit according to any one of claims 1 to 5, 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 a refrigerant pressure at the outlet of the first condenser (2) at a current outdoor temperature; If the refrigerant pressure is less than the first switching pressure, the indoor heat exchange system is closed, the first electrically controlled valve (6) is opened, and the second electrically controlled valve (11) is closed; If the refrigerant pressure is greater than or equal to the first switching pressure and less than or equal to the second switching pressure, the unit load rate in the corresponding room and the preset target load are obtained; if the unit load rate is greater than the target load rate, the indoor heat exchange system is turned on, and the first electrically controlled valve (6) and the second electrically controlled valve (11) are turned on; if the unit load rate is less than or equal to the target load rate, the indoor heat exchange system is turned off, the first electrically controlled valve (6) is turned on, and the second electrically controlled valve (11) is turned off; If the refrigerant pressure is greater than the second switching pressure, the indoor heat exchange system is turned on, the first electrically controlled valve (6) is closed, and the second electrically controlled valve (11) is turned on.

7. The control method according to claim 6, characterized in that: The step of starting the indoor heat exchange system, and starting the first electrically controlled valve (6) and the second electrically controlled valve (11) comprises: The first electrically controlled valve (6) maintains a maximum opening, the second electrically controlled valve (11) performs PID regulation according to the pressure of the second condenser (10) of the indoor heat exchange system, the compressor (9) of the indoor heat exchange system performs PID calculation according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and adjusts the operating frequency of the compressor (9) through the PID value.

8. The control method according to claim 6, characterized in that: The steps of opening the indoor heat exchange system, closing the first electrically controlled valve (6), and opening the second electrically controlled valve (11) include: The second electrically controlled valve (11) performs PID regulation according to the pressure of the second condenser (10) of the indoor heat exchange system, and the compressor (9) of the indoor heat exchange system performs PID calculation according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and adjusts the operating frequency of the compressor (9) through the PID value.

9. The control method according to claim 6 or 8, characterized in that: The steps after starting the indoor heat exchange system, closing the first electrically controlled valve (6), and opening the second electrically controlled valve (11) include: The unit load rate in the corresponding room 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 electrically controlled valve (6) is opened, and the second electrically controlled valve (11) is closed.

10. The control method according to claim 9, characterized in that: The steps of closing the indoor heat exchange system and opening the first electrically controlled valve (6) include: PID calculation is performed according to the corresponding indoor preset temperature and the corresponding indoor actual temperature, and the opening degree of the first electrically controlled valve (6) is adjusted according to the PID value.

11. The control method according to claim 6, characterized in that: A preset third switching pressure is obtained, the third switching pressure being less than the second switching pressure, and it is determined whether the refrigerant pressure is less than the third switching pressure. If so, only the external fan corresponding to the first condenser (2) is turned on; if not, the external fan and the spray device are turned on at the same time.

12. The control method according to claim 11, characterized in that: The rotation speed of the outdoor fan or the spraying water volume of the spraying device is PID-regulated according to the refrigerant pressure.

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