Energy-saving temperature and humidity decoupling control cold and hot dual-function air conditioning system and control method thereof

Abstract

The invention discloses an energy-saving temperature and humidity decoupling control cold and hot dual-function air conditioning system and a control method thereof, and belongs to the technical field of air conditioning, the system comprises a precise air conditioning system, an air handling unit and a control unit, the control unit is connected with the precise air conditioning system and the air handling unit, and the precise air conditioning system is connected with the air handling unit. The control method comprises the following steps that S1, the air conditioning system switches operation modes; s2, adjusting parallel air ducts of the air conditioning system through the air valve matrix; s3, the decoupling economizer carries out decoupling control; s4, any one of five working conditions of pure refrigeration regulation, low-temperature and constant-humidity regulation, medium-temperature and constant-humidity regulation, high-temperature and constant-humidity regulation and pure heat supply regulation is operated; and S5, the air handling unit is controlled to execute air volume adjustment, air filtration, surface cooling and reheating. The system can meet various complex air treatment requirements of a user, and has a wide temperature and humidity application range and precise temperature and humidity regulation and control precision.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioning, and in particular relates to an energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system and a control method thereof. Background Art

[0002] In the current era of accelerated development of informatization, the requirements for precision environmental control of high-end equipment and production processes are increasing. The reliability of these equipment and production not only depends on constant temperature conditions, but also puts forward extremely high sensitivity, accuracy and stability requirements for humidity control. According to the national standard GB / T 25858, ordinary precision air conditioners can simultaneously or individually maintain temperature fluctuations of ±1℃~±0.5℃ and relative humidity fluctuations of ±5%RH~±2%RH in the regulated closed domain; while high-precision constant temperature and humidity air conditioners can simultaneously or individually maintain temperatures of ±0.5℃~±0.3℃ and relative humidity of ±2%RH. The high-precision precision air conditioner designed and produced by the patentee of this invention can control the outlet temperature of the air at ≤±0.1℃, and the relative humidity fluctuations of ≤1~2%RH.

[0003] From the perspective of efficient operation of air-conditioning equipment, although traditional air-conditioning equipment can meet the most basic temperature regulation needs, it performs poorly in terms of precise humidity control. Especially under extreme climate conditions, such as high temperature and high humidity or low temperature and low humidity, the performance of traditional air-conditioning equipment declines sharply. In addition, when traditional air-conditioning equipment jointly controls temperature and humidity, it is often difficult to effectively decouple the interaction between temperature and humidity, which is not conducive to achieving independent and precise regulation between the two.

[0004] From the perspective of safe operation of the air conditioning system, if the return air sucked by the compressor contains liquid refrigerant, since liquid is not easy to be compressed, when a large amount of liquid is squeezed by the compressor piston, it may cause liquid hammer, causing serious impact on the internal parts of the compressor, resulting in deformation and breakage of the valve plate. This impact injury has a great impact on the performance of the compressor and may even prevent it from working normally. Therefore, in order to ensure the safe operation of the system, the refrigerant at the compressor inlet must be a vapor with a certain degree of superheat, and the system design should be optimized and a series of auxiliary components should be configured.

[0005] From the perspective of energy-saving operation of air-conditioning systems, energy conservation and emission reduction have become an inevitable demand for social development in the context of increasingly severe global energy problems. How to effectively reduce energy consumption and improve energy utilization efficiency while meeting people's demand for environmental control is a major challenge faced by energy conversion systems when upgrading and developing. Precision air conditioners on the current market generally face significant problems such as excessive energy consumption and large carbon emissions. First, compared with ordinary household air conditioners, precision air conditioning systems need to simultaneously regulate multiple parameters of indoor air, and are often more complex in structure, involving more detailed energy conversion processes, and therefore consume more energy during operation. Second, unlike traditional air conditioners that focus on adjusting personnel comfort, precision air conditioners are mainly used in computer rooms, precision processing, biological cultivation, and other working conditions that require precise control of temperature and humidity. The design focus is on ensuring the stability and reliability of system operation, so the operating condition fluctuation and parameter setting accuracy are more stringent, resulting in the need for more frequent regulation of air conditioning units to meet the corresponding high-precision requirements, which undoubtedly increases power consumption. Thirdly, a significant difference from ordinary household air conditioners is that precision air conditioners often need to run continuously for a long time without stopping. If the energy efficiency level of the unit is not improved, the high energy consumption problem mentioned above will be further amplified over the years. Summary of the invention

[0006] The key technical routes for developing a new generation of technological air-conditioning systems with precise temperature and humidity control capabilities are: first, upgrading the control system (including algorithms); second, developing new refrigeration / heating systems (including structures). The present invention is based on the second key technical route. In view of the deficiencies in the prior art, the present invention discloses an energy-saving temperature and humidity decoupling control hot and cold dual-function air conditioning system and its control method, which can meet the various complex air treatment needs of users, and has a wide temperature and humidity application range and precise temperature and humidity control accuracy. Through the uniquely designed energy conversion process and the optimized decoupled node balance relationship, combined with the innovation of components and efficient condensation heat recovery and regulation and utilization, the present invention achieves good energy-saving effects while ensuring that the unit outputs constant temperature and humidity air. In particular, the introduction of a precision air-conditioning system after the parallel design of the air duct, combined with the air valve matrix adjustment technology, can achieve the selective and precise introduction of air after being processed by each heat exchanger. When the opening of each air valve and the electronic expansion valve are finely adjusted at the same time, the system of the present invention can dynamically adjust the temperature and humidity parameters of the air in the controlled space to quickly respond to changes in external environmental conditions.

[0007] The technical solution adopted by the present invention is to provide an energy-saving temperature and humidity decoupling control cold and hot dual-function air conditioning system, including a precision air-conditioning system, an air handling unit and a control unit. The control unit is connected to the precision air-conditioning system and the air handling unit. The precision air-conditioning system is connected to the air handling unit. The precision air-conditioning system provides the required cooling or heat for the air handling unit.

[0008] The air handling unit includes a first heat exchanger, a second heat exchanger and a reheater, the precision air conditioning system includes a compressor, an oil separator, a decoupling economizer, a first drying filter, a second drying filter, a gas-liquid separator, a third drying filter, a first non-return valve, a second non-return valve, and a third non-return valve. The first heat exchanger is connected to the decoupling economizer through the third electric three-way valve, the decoupling economizer is connected to the third electric three-way valve and the four-way reversing valve through the fourth electric three-way valve, the decoupling economizer is connected to the second heat exchanger and the first electric three-way valve, the second heat exchanger is connected to the four-way reversing valve, and the four-way reversing valve is connected connected to the gas-liquid separator, the compressor, and the oil separator; the oil separator is connected to the four-way reversing valve and the reheater; the reheater is connected to the second filter drier, the electronic expansion valve, the first check valve, the second check valve, the first thermal expansion valve, and the first filter drier; the first electric three-way valve is connected to the line between the second check valve and the first check valve; the line between the second check valve and the first check valve is connected to the first heat exchanger through the second electric three-way valve; the second electric three-way valve is connected to the line between the electronic expansion valve and the first thermal expansion valve through the third filter drier, the second thermal expansion valve, and the third check valve;

[0009] A first air supply regulator, a first primary air filter, a first medium-efficiency air filter, a first heat exchanger, and a first fan are arranged on a parallel branch of the air duct. The branch is connected to the reheater and the second fan through a No. 2 air valve, and is connected to the outside through a No. 1 air valve. A second air supply regulator, a second primary air filter, a second medium-efficiency air filter, a second heat exchanger, and a third fan are arranged on another parallel branch of the air duct. The branch is connected to the reheater and the second fan through a No. 3 air valve, and is connected to the outside through a No. 4 air valve.

[0010] It mainly involves dual operating modes (medium-low temperature mode, medium-high temperature mode), parallel duct design, air conditioning and refrigeration system, air handling unit, and decoupling economizer.

[0011] The dual operation mode of the system optimizes the management of the system's pipelines by using components such as a four-way reversing valve, a one-way valve, and a three-way valve to achieve regulation of the refrigerant flow characteristics and system functions. The air conditioning system can switch to the corresponding operation mode according to different working conditions and user needs, and has a wide temperature and humidity application range and strong adaptability. Compared with the separate purchase of refrigeration equipment and heating equipment, the present invention integrates refrigeration, heating, and dehumidification functions, which can save space, reduce equipment operation and maintenance costs, and avoid the economic and practical problems caused by multiple purchases and installations.

[0012] The medium and low temperature mode refers to the operating state of the air conditioning system when it meets the user's demand for medium and low air outlet temperature control. The medium and low temperature mode is the operating mode of the system. At this time, the decoupling economizer is used to realize the heat exchange between the refrigerant vapor at the outlet of the first heat exchanger and the refrigerant liquid at the outlet of the second heat exchanger, and plays the role of an economizer. Specifically, when the system is in the medium and low temperature mode, the first heat exchanger plays the role of an evaporator, and the second heat exchanger plays the role of a condenser. The refrigerant absorbs heat and changes phase in the first heat exchanger, leaves the first heat exchanger in a vapor state, and flows into the decoupling economizer through the third electric three-way valve. The decoupling economizer is used to realize the heat exchange between the lower temperature refrigerant vapor flowing through the first heat exchanger and the higher temperature refrigerant liquid of the second heat exchanger. After the refrigerant flows out of the decoupling economizer, it flows into the four-way reversing valve through the fourth electric three-way valve. After being adjusted by the four-way reversing valve, it enters the compressor in a completely gas phase state through the gas-liquid separator. It is then compressed into a high-temperature and high-pressure gaseous refrigerant, and after passing through the oil separator, it is divided into two streams, which enter the branch where the second heat exchanger is located and the branch where the reheater is located. For the stream entering the branch where the second heat exchanger is located, the high-temperature and high-pressure gaseous refrigerant first enters the four-way reversing valve. After being adjusted by the four-way reversing valve, it enters the second heat exchanger, releases the condensation heat into the air duct, and the refrigerant is converted from a gas phase to a liquid phase. Subsequently, this high-temperature refrigerant liquid flows into the decoupling economizer and exchanges heat with the lower-temperature refrigerant vapor from the first heat exchanger. The subcooled refrigerant after cooling flows to the first expansion valve through the first electric three-way valve and the first drying filter. Under the throttling effect of the first expansion valve, the pressure and temperature of the refrigerant are greatly reduced, and then merge with the low-temperature and low-pressure refrigerant diversion stream from the branch where the reheater is located. This is the confluence point of the two refrigerants. As mentioned above, the separation point of these two refrigerant streams is after the oil separator, and they enter the branch where the second heat exchanger is located and the branch where the reheater is located respectively. For the diversion stream entering the branch where the reheater is located, the heat is first released in the reheater to fine-tune the quality of the output air, and then flows to the electronic expansion valve through the second dryer. Under the throttling effect of the electronic expansion valve, the pressure and temperature of the refrigerant are greatly reduced, and then merged with the low-temperature and low-pressure refrigerant diversion stream from the branch where the second heat exchanger is located. The merged low-temperature and low-pressure gas-liquid two-phase (mainly liquid phase) refrigerant stream enters the first heat exchanger through the second electric three-way valve, where it evaporates and absorbs heat to achieve refrigeration. If it works in a cycle, the basic core functions in the medium and low temperature mode can be realized. In the medium and low temperature mode of the system, the refrigerant liquid on the second heat exchanger side is supercooled and the refrigerant vapor on the first heat exchanger side is superheated, which is conducive to improving the circulation efficiency of the system.

[0013] The medium-high temperature mode refers to the operating state of the air-conditioning system when it meets the user's demand for medium-high outlet air temperature control. The medium-high temperature mode is the operating mode of the system, and the decoupling economizer plays the role of a decoupler at this time. The heat in the environment is absorbed through the pipeline, and the cold capacity of the throttled two-phase fluid is unloaded, thereby reducing the evaporative heat exchange load in the second heat exchanger. Specifically, the first heat exchanger plays the role of a condenser, and the second heat exchanger plays the role of an evaporator. The refrigerant evaporates and absorbs heat in the second heat exchanger, and after being converted into a gaseous state, it flows into the four-way reversing valve. After being adjusted, it passes through the gas-liquid separator and enters the compressor in a completely gaseous state. It is then compressed into a high-temperature and high-pressure gaseous refrigerant, and after passing through the oil separator, it is divided into two streams, which enter the branch where the first heat exchanger is located and the branch where the reheater is located. For the stream entering the branch where the first heat exchanger is located, the high-temperature and high-pressure gaseous refrigerant first enters the four-way reversing valve. After the four-way reversing valve is adjusted, the third electric three-way valve and the fourth electric three-way valve are used to bypass the decoupling economizer, and the refrigerant flows directly into the first heat exchanger. After the high-temperature and high-pressure refrigerant releases the condensation heat in the first heat exchanger, it flows to the second expansion valve through the second electric three-way valve and the third drying filter. Under the throttling effect of the second expansion valve, the pressure and temperature of the refrigerant are greatly reduced, and then it merges with the low-temperature and low-pressure refrigerant branch from the branch where the reheater is located. This is the confluence point of the two refrigerants. As mentioned above, the separation point of the two refrigerants is after the oil separator, and is divided into the branch where the first heat exchanger is located and the branch where the reheater is located. For the branch that enters the branch where the reheater is located, the heat is first released in the reheater to further increase the temperature of the output air and improve the heating capacity of the system. Then, it flows to the electronic expansion valve through the second dryer. Under the throttling effect of the electronic expansion valve, the pressure and temperature of the refrigerant are greatly reduced, and then merged with the low-temperature and low-pressure refrigerant branch from the branch where the first heat exchanger is located. The merged low-temperature and low-pressure gas-liquid two-phase (mainly liquid phase) refrigerant flow enters the decoupling economizer through the first electric three-way valve. The refrigerant that has completed the cold unloading of the decoupling economizer returns to the second heat exchanger for evaporation and heat absorption. If it works in a cycle, the basic core functions in the medium and high temperature mode can be realized. In the medium and high temperature mode, the system needs to increase the circulation flow of the refrigerant to compensate for the cold loss of the decoupling economizer unloading and meet specific dehumidification requirements. This can correspondingly increase the refrigerant flow rate, enhance the heat exchange efficiency on both sides of the condenser and the reheater, and further increase the outlet temperature of the treated air.

[0014] The parallel design of the air duct is to achieve the mixing of the air in the two branches flowing through the evaporator and the condenser in the optimal proportion by means of the corresponding switch combination scheme of the No. 1 air valve, the No. 2 air valve, the No. 3 air valve and the No. 4 air valve through the air valve matrix adjustment technology. The mixed air is transported to the branch where the reheater is located, and the air temperature is further adjusted to the required set value, thereby completing a complete air treatment process. Specifically, there are two heat exchange branches for the air to be treated in the system, which pass through the evaporator and the condenser respectively and play different roles. The main function of the evaporator side branch is to reduce the temperature of the air to be treated to below the dew point temperature, thereby promoting the analysis of water in the air to achieve the effect of cooling and dehumidification; while the main function of the condenser side branch is to increase the temperature of the air to be treated to achieve a higher target output temperature. After the air treated by the parallel branch is mixed, it enters the reheater for further temperature and humidity adjustment. The main function of the reheater is to heat the mixed air to compensate for the possible heat loss in the evaporator process, thereby ensuring that the output air can accurately meet the required temperature and humidity requirements. During the operation of the entire system, the temperature and humidity of the treated gas can be precisely adjusted by adjusting the opening of the air valves on the evaporator and condenser sides (0-100%).

[0015] The air conditioning system can adapt to various air treatment requirements under complex working environment conditions. Under any operating condition within the applicable range, the system can meet five control requirements: pure cooling, low temperature constant humidity, medium temperature constant humidity, high temperature constant humidity and pure heating.

[0016] First, when pure refrigeration control is required (only refrigeration requirement, but no constant humidity requirement), the air conditioning system operates in mode. In addition, the No. 1 air valve leading to the outdoors of the branch where the first heat exchanger is located is closed, and the No. 2 air valve leading to the indoors is opened; at the same time, the No. 3 air valve leading to the indoors of the branch where the second heat exchanger is located is closed, and the No. 4 air valve leading to the outdoors is opened; the electronic expansion valve on the reheater side is dynamically adjusted within a small opening range. At this time, the air to be treated passes through the first heat exchanger and the reheater in turn, respectively realizing rapid large temperature difference cooling, supercooling and subsequent small temperature difference callback of the treated air, and finally achieving precise and stable temperature control before output.

[0017] Secondly, when low temperature and constant humidity control is required (constant temperature and humidity are required, and a lower temperature needs to be reached), the air conditioning system operates in mode. The No. 1 air valve leading to the outdoors of the branch where the first heat exchanger is located is closed, and the No. 2 air valve leading to the indoors is opened; at the same time, the No. 3 air valve leading to the indoors of the branch where the second heat exchanger is located is closed, and the No. 4 air valve leading to the outdoors is opened; the electronic expansion valve on the reheater side is dynamically adjusted within a large opening range. At this time, the air to be treated passes through the first heat exchanger and the reheater in turn, respectively realizing the cooling and dehumidification of the treated air and the subsequent controlled temperature increase, and outputting it after precise and stable temperature control. The difference between this low temperature and constant humidity control mode and the aforementioned pure refrigeration mode is that at this time, the reheater realizes the recovery of more condensation heat to compensate for the heat loss of the treated air during the cooling and dehumidification process, and has the ability to accurately adjust the outlet temperature of the treated gas within a relatively larger temperature change range.

[0018] Third, when medium temperature constant humidity control is required (constant temperature and humidity are required, and the temperature reached must be moderate), the system can operate in mode. The flow of dehumidified gas to the room is controlled by the opening size of the No. 1 air valve leading to the outside and the No. 2 air valve leading to the room on the side of the first heat exchanger (as an evaporator). At the same time, the flow of heated gas to the room is controlled by the opening size of the No. 3 air valve leading to the room and the No. 4 air valve leading to the outside on the side of the second heat exchanger (playing a condensing role). After the two air flows are mixed, they pass through the reheater to complete the subsequent treatment process of the air, and the electronic expansion valve is dynamically adjusted. At this time, the system is in medium temperature constant humidity control mode. Compared with the control strategy under the aforementioned low temperature and constant humidity, this control strategy recovers the heat released by the second heat exchanger that was originally discharged directly to the outside by adjusting the opening of each air valve. At the same time, the dehumidification capacity of the system can be adjusted by dynamically adjusting the opening size of the air valve on the first heat exchanger side; the amount of condensation heat recovery entering the room can be adjusted by dynamically adjusting the opening size of the air valve on the second heat exchanger side.

[0019] Fourth, when high temperature constant humidity control is required (constant temperature and humidity are required, and the temperature reached needs to be high), the system can be operated in mode, which is significantly different from the system operating in mode when the aforementioned medium temperature constant humidity control is required. The flow of heated gas to the room is controlled by the opening size of the No. 1 air valve leading to the outside and the No. 2 air valve leading to the room on the side of the first heat exchanger (as a condenser). At the same time, the flow of dehumidified gas to the room is controlled by the opening size of the No. 3 air valve leading to the room and the No. 4 air valve leading to the outside on the side of the second heat exchanger (playing an evaporation role). After the two air flows are mixed, the subsequent treatment process of the air is completed through the reheater side, and the electronic expansion valve is dynamically adjusted. At this time, the system is in high temperature constant humidity control mode. Compared with the control strategy under the medium temperature constant humidity requirement, the decoupling economizer is no longer a component to improve the safety and economic efficiency of the system operation, but by unloading the refrigerant coldness in the dehumidification heat exchanger in advance, the dehumidification amount of the heat exchanger for the air flowing through is reduced. If the dehumidification capacity needs to be increased later, it can be achieved by increasing the refrigerant circulation volume. The advantage of this control strategy is that while maintaining a constant relative humidity, the system can output air at a higher temperature (relative to room temperature), that is, the temperature range that can be heated is wider to meet the needs of a high temperature and constant humidity environment.

[0020] Fifth, when pure heating control is required (only heating requirement, but no constant humidity requirement), the system operates in mode. The No. 1 air valve leading to the outside on the first heat exchanger side is closed, and the No. 2 air valve leading to the room is opened; at the same time, the No. 3 air valve leading to the room on the second heat exchanger side is closed, and the No. 4 air valve leading to the outside is opened; and then the throttling adjustment of the electronic expansion valve on the reheater side is performed. At this time, the air entering the room passes through the first heat exchanger and the reheater successively for two step-by-step temperature rises, realizing high-precision pure heating control of the air.

[0021] Preferably, the air handling system includes an air volume regulating section, an air filtering section, a surface cooling section, and a reheating section. The air volume regulating section controls the air handling volume by the cross-sectional flux opened at the fresh air inlet; the filtering section first performs a primary filtration on the input fresh air to prevent the impurities and dust therein from affecting the accuracy of the subsequent air handling process, while ensuring the cleanliness of the air handling unit; then a medium-efficiency filtration is performed to further filter the impurities therein to meet the requirements for air cleanliness. The surface cooling section has a low-temperature and low-pressure refrigerant flowing through it, which is used to cool and dehumidify the air passing through it. When the air temperature is lower than the dew point temperature, the water molecules in the air are liquefied on the surface of the surface cooler, and the water vapor content in the air is reduced, thereby achieving the purpose of dehumidification. The reheating section uses a reheater to recycle the heat released by the refrigerant during the condensation process to achieve heating treatment of the air.

[0022] Preferably, the decoupling economizer is used to achieve heat exchange between the lower temperature refrigerant vapor flowing through the first heat exchanger and the higher temperature refrigerant liquid in the second heat exchanger in the medium and low temperature mode, so that the refrigerant liquid is supercooled and the vapor is superheated. After being processed by the decoupling economizer, the supercooled liquid can generate a larger unit mass cooling capacity after throttling. Under the condition of the same required cooling capacity, the refrigerant circulation flow in the system can be reduced, the energy consumption of the compressor can be reduced, and the advantage of energy saving can be brought into play. At the same time, moderate suction superheat can also eliminate the risk of compressor liquid hammer, increase exhaust heat, and improve the overall cycle efficiency.

[0023] In the medium and high temperature mode, the decoupled economizer plays the role of a decoupler, enabling the system to decouple the two parameters of air temperature and humidity, and realize independent control of the two parameters of temperature and humidity within a certain range. After the four-way reversing valve is adjusted, the refrigerant will bypass the decoupled economizer and flow directly into the first heat exchanger by using the third electric three-way valve and the fourth electric three-way valve. There is only gas-liquid two-phase refrigerant in the decoupled economizer that will flow into the second heat exchanger. In addition, the pipeline along the way absorbs part of the heat in the environment (in the form of air cooling), weakens its refrigeration release in the second heat exchanger, and realizes the function of unloading the refrigeration capacity. The effective unloading of the refrigeration capacity is conducive to the system outputting higher temperature air. If the circulation volume of the refrigerant in the system is increased at the same time, the heat exchange capacity of the second heat exchanger and the reheater can be further enhanced, so that the temperature of the gas to be treated can be further increased, and the user's needs for higher temperature air control can be better met.

[0024] A control method for the energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system as described above comprises the following steps:

[0025] S1, the air conditioning system switches the operating mode, the operating modes include medium-low temperature mode and medium-high temperature mode;

[0026] S2, regulating the parallel air ducts of the air conditioning system through the air valve matrix;

[0027] S3, the decoupling economizer of the air conditioning system performs decoupling control;

[0028] S4. The air conditioning system operates in any of the five operating conditions: pure cooling control, low temperature constant humidity control, medium temperature constant humidity control, high temperature constant humidity control, and pure heating control;

[0029] S5. Control the air handling unit to perform air volume regulation, air filtration, surface cooling and reheating.

[0030] The beneficial effects of the present invention are as follows: the present invention provides an energy-saving temperature and humidity decoupling control hot and cold dual-function air conditioning system and its control method, which can meet the user's various complex air processing needs, and has a wide temperature and humidity application range and precise temperature and humidity control accuracy. Through a uniquely designed energy conversion process and optimized decoupling of the balance relationship between each node, combined with the innovation of components and efficient condensation heat recovery and regulation and utilization, the present invention achieves good energy-saving effects while ensuring that the unit outputs constant temperature and humidity air. In particular, the introduction of a precision air-conditioning system with a parallel design of air ducts, combined with the air valve matrix adjustment technology, can achieve the selective and precise introduction of air processed by each heat exchanger. When the opening of each air valve and electronic expansion valve is finely adjusted at the same time, the system of the present invention can dynamically and linkedly adjust the temperature and humidity parameters of the air in the controlled space to quickly respond to changes in external environmental conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of the low temperature mode system in the air conditioning system;

[0032] Figure 2 It is a system flow chart of high temperature mode in air conditioning system;

[0033] Figure 3 It is a schematic diagram of the structure of the air handling unit.

[0034] In the figure: 1. compressor; 2. oil separator; 3. four-way reversing valve; 4. second heat exchanger; 5. decoupling economizer; 6. first electric three-way valve; 7. first filter drier; 8. first expansion valve; 9. reheater; 10. second filter drier; 11. electronic expansion valve; 12. second electric three-way valve; 13. first heat exchanger; 14. third electric three-way valve; 15. fourth electric three-way valve; 16. gas-liquid separator; 17. third filter drier; 18. second expansion valve; 19. No. 1 air valve; 20. No. 2 air valve; 21. No. 3 air valve; 22. No. 4 air valve; 23. first air supply regulator; 24. first primary air filter; 25. first medium-efficiency air filter; 26. first fan; 27. second fan; 28. second air supply regulator; 29. ​​second primary air filter; 30. second medium-efficiency air filter; 31. third fan. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described below in detail with reference to the accompanying drawings in the embodiments of the present invention, which is only used to explain the present invention and should not be construed as limiting the present invention.

[0036] like Figure 1 , Figure 3As shown, an embodiment of the present invention provides an energy-saving temperature and humidity decoupling control cold and hot dual-function air conditioning system, including a precision air-conditioning system, an air handling unit and a control unit. The control unit is connected to the precision air-conditioning system and the air handling unit. The precision air-conditioning system is connected to the air handling unit. The precision air-conditioning system provides the required cooling or heat for the air handling unit.

[0037] The air handling unit includes a first heat exchanger 13, a second heat exchanger 4 and a reheater 9, and the precision air conditioning system includes a compressor 1, an oil separator 2, a decoupling economizer 5, a first drying filter 7, a second drying filter 10, a gas-liquid separator 16, a third drying filter 17, a first one-way valve, a second one-way valve, and a third one-way valve. The first heat exchanger 13 is connected to the decoupling economizer 5 through a third electric three-way valve 14, and the decoupling economizer 5 is connected to the third electric three-way valve 14 and the four-way reversing valve 3 through a fourth electric three-way valve 15. The decoupling economizer 5 is connected to the second heat exchanger 4 and the first electric three-way valve 6, and the second heat exchanger 4 is connected to the four-way reversing valve 3. The four-way reversing valve 3 is connected to the gas-liquid separator 16, the compressor 1, and the oil separator 2, the oil separator 2 is connected to the four-way reversing valve 3 and the reheater 9, the reheater 9 is connected to the second filter dryer 10, the electronic expansion valve 11, the first check valve, the second check valve, the first thermal expansion valve 8, and the first filter dryer 7, the first electric three-way valve 6 is connected to the line between the second check valve and the first check valve, the line between the second check valve and the first check valve is connected to the first heat exchanger 13 through the second electric three-way valve 12, and the second electric three-way valve 12 is connected to the line between the electronic expansion valve 11 and the first thermal expansion valve 8 through the third filter dryer 17, the second thermal expansion valve 18, and the third check valve;

[0038] A first air supply regulator 23, a first primary air filter 24, a first medium-efficiency air filter 25, a first heat exchanger 13, and a first fan 26 are arranged on a parallel branch of the air duct. The branch is connected to the reheater 9 and the second fan 27 through the No. 2 air valve 20, and is connected to the outside through the No. 1 air valve 19. A second air supply regulator 28, a second primary air filter 29, a second medium-efficiency air filter 30, a second heat exchanger 4, and a third fan 31 are arranged on another parallel branch of the air duct. The branch is connected to the reheater 9 and the second fan 27 through the No. 3 air valve 21, and is connected to the outside through the No. 4 air valve 22.

[0039] The core components related to the dual functions of cooling / heating include: compressor 1, oil separator 2, four-way reversing valve 3, second heat exchanger 4, decoupling economizer 5, first electric three-way valve 6, first expansion valve 8 (a thermal expansion valve is specifically selected in the specific implementation), reheater 9, electronic expansion valve 11, second electric three-way valve 12, first heat exchanger 13, third electric three-way valve 14, fourth electric three-way valve 15; second expansion valve 18 (a thermal expansion valve is specifically selected in the specific implementation); the core components related to air temperature and humidity reprocessing include: first heat exchanger 13, second heat exchanger 4, reheater 9, No. 1 air valve 19, No. 2 air valve 20, No. 3 air valve 21, and No. 4 air valve 22.

[0040] Specific implementation method 1, in the pure cooling control mode, as Figure 1 As shown, the air conditioning system is operating in medium and low temperature mode, which has good economic and energy-saving effects.

[0041] The No. 1 air valve 19 leading to the outside of the branch where the first heat exchanger 13 is located is closed, and the No. 2 air valve 20 leading to the indoors is opened; at the same time, the No. 3 air valve 21 leading to the indoors of the branch where the second heat exchanger 4 is located is closed, and the No. 4 air valve 22 leading to the outdoors is opened. The electronic expansion valve 11 on the side of the reheater 9 is dynamically adjusted within a small opening range. At this time, the air to be treated passes through the first heat exchanger 13 and the reheater 9 in turn, respectively realizing rapid large temperature difference cooling, supercooling and subsequent small temperature difference callback of the treated air, and finally achieving accurate and stable temperature control before output.

[0042] In the specific implementation, in the medium and low temperature mode, the refrigerant absorbs heat and changes phase in the first heat exchanger 13 (as an evaporator), leaves the first heat exchanger 13 in a vapor state, passes through the third electric three-way valve 14, and flows into the decoupling economizer 5. It flows out of the decoupling economizer 5 in a superheated vapor state, passes through the fourth electric three-way valve 15, and flows into the four-way reversing valve 3. After the four-way reversing valve 3 is adjusted, it passes through the gas-liquid separator 16 and enters the compressor 1 in a completely gaseous state. It is then compressed into a high-temperature and high-pressure gaseous refrigerant, and after passing through the oil separator 2, it is divided into two streams, which enter the branch where the second heat exchanger 4 is located and the branch where the reheater 9 is located. For the stream entering the branch where the second heat exchanger 4 is located, the high-temperature and high-pressure gaseous refrigerant first enters the four-way reversing valve 3. After the four-way reversing valve 3 is adjusted, it enters the second heat exchanger 4, releases the condensation heat into the air duct, and the refrigerant is converted from a gas phase state to a liquid phase state. It then flows into the decoupling economizer 5, and exchanges heat with the relatively low-temperature refrigerant vapor from the first heat exchanger 13 (acting as a condenser). The subcooled refrigerant after cooling flows to the first thermal expansion valve 8 through the first electric three-way valve 6 and the first drying filter 7. Under the throttling effect of the first thermal expansion valve 8, the pressure and temperature of the refrigerant are greatly reduced, and then merge with the low-temperature and low-pressure refrigerant branch stream from the branch where the reheater 9 is located. This is the confluence point of the two refrigerants. The separation point of the two refrigerants is after the oil separator 2, and they enter the branch where the second heat exchanger 4 is located and the branch where the reheater 9 is located, respectively. For the branch stream entering the branch where the reheater 9 is located, the heat is first released in the reheater 9 to fine-tune the quality of the output air, and then flows to the electronic expansion valve 11 through the second dryer 10. Under the throttling effect of the electronic expansion valve 11, the pressure and temperature of the refrigerant are greatly reduced, and then merge with the low-temperature and low-pressure refrigerant flow from the branch where the second heat exchanger 4 is located. The merged low-temperature and low-pressure gas-liquid two-phase (mainly liquid phase) refrigerant flow passes through the second electric three-way valve 12 and enters the first heat exchanger 13, where it evaporates and absorbs heat to achieve refrigeration. In this cycle, the basic core function in the medium and low temperature mode can be achieved.

[0043] In the specific implementation, R410A is selected as the refrigerant. The operating conditions of the air-conditioning system when the decoupling economizer 5 is not introduced are: the evaporation pressure of R410A after throttling on the first thermal expansion valve 8 side is 0.8 MPa, the evaporation pressure of the refrigerant after throttling on the electronic expansion valve 11 side is 0.8 MPa, the condensing pressure is 2.0 MPa, the suction superheat of the compressor 1 inlet is 5K, the liquid subcooling of the reheater 9 outlet is 1K, the liquid subcooling of the second heat exchanger 4 outlet is 2K, and the refrigerant flow rates of the first thermal expansion valve 8 branch and the electronic expansion valve 11 branch account for 0.9 and 0.1 (i.e. 90% and 10%) of the total trunk flow, respectively.

[0044] Among them, the motor input power is calculated using the following formula:

[0045]

[0046] Where η el For electrical efficiency.

[0047] The electrical efficiency is calculated as follows:

[0048] η el =η i ·η t ·η l ·η m ·η mo (2)

[0049] In the formula, the indicating efficiency η i Indicates the relative size of aerodynamic loss and heat exchange loss during compression of gas; heating efficiency η t Indicates the heating loss during the air intake process; leakage efficiency η l Represents the energy loss caused by cylinder leakage; mechanical efficiency η m Mainly depends on the viscosity of the oil and refrigerant mixture; η mo Indicates motor efficiency.

[0050] It is calculated that when the decoupling economizer 5 is not introduced, the refrigeration cycle performance under the above working conditions is: the theoretical power consumption of the compressor under the corresponding unit mass flow is 25.75 kJ, the unit mass cooling capacity is 177.95 kJ, and the corresponding motor input is 51.50 kJ; the system refrigeration performance coefficient (COP) is 3.46.

[0051] In the specific implementation, the operating conditions of the air conditioning system after the decoupling economizer 5 are introduced: the evaporation pressure of the refrigerant after throttling on the first thermal expansion valve 8 side, the evaporation pressure of the refrigerant after throttling on the electronic expansion valve 11 side, the liquid subcooling degree at the outlet of the reheater 9, the condensing pressure, the electrical efficiency η el , the proportion of the refrigerant flow rate of the first thermal expansion valve 8 branch and the electronic expansion valve 11 branch to the total flow rate of the trunk line, and other parameters are completely consistent with the above-mentioned case where the decoupling economizer 5 is not introduced; the refrigerant is still R410A; after the decoupling economizer 5 acts, the subcooling degree of the refrigerant liquid is 6K, and the superheat of the suction gas at the inlet of the compressor 1 is 10K. It can be calculated that the refrigeration cycle performance after the introduction of the decoupling economizer 5 is that the theoretical power consumption of the compressor under the corresponding unit mass flow is 26.62kJ, the unit mass cooling capacity is 189.48kJ, and the corresponding motor input is 53.25kJ; the system COP is increased to 3.56, and the comprehensive performance is improved by 2.89%.

[0052] The quantitative analysis of the specific implementation mode 2 and the specific implementation mode 3 are both based on the numerical simulation model of the precision air conditioning system, especially the key evaporator model and condenser model, which are used to simulate and calculate the air outlet state after the processed air and the refrigerant under different inlet states exchange heat after the specifications and dimensions of the heat exchanger are determined according to certain rules. The main assumptions and specific control equations based on them are as follows:

[0053] The following main assumptions are used when modeling the evaporator: (1) The refrigerant and air are in countercurrent; (2) The radial temperature of the tube wall is consistent. For each microelement along the tube length, the physical properties of the refrigerant side, the air side, and the tube wall are considered to be consistent, and the thermal resistance of the tube wall is not considered; (3) From the perspective of convergence speed, considering that the superheated zone is short and the acceleration pressure drop is small, the superheated zone pressure drop is ignored.

[0054] In the model, the evaporator includes two phase zones: the two-phase zone and the superheat zone, and each root zone is divided into several micro-elements. For the two-phase zone, the temperature change depends on the pressure drop, and the refrigerant enthalpy value changes greatly. Therefore, the micro-element division is achieved by dividing the enthalpy difference equally; for the superheat zone, under the assumption that the pressure remains unchanged, the refrigerant temperature changes greatly, and the micro-element is divided by dividing the refrigerant temperature equally.

[0055] The following specific governing equations are used when modeling the evaporator:

[0056] Air side energy equation:

[0057] Q a =m a (h a,in -h a,out )(3)

[0058] Moist air humidity equation:

[0059] -m a dW a =h d (W a -W w )dA a (4)

[0060] Where W w W is the saturated humidity content of moist air corresponding to the temperature of the outer wall of the tube; a To calculate the average moisture content on the air side of the microelement.

[0061] Refrigerant side energy equation:

[0062] Q r =m r (h r1 -h r2 )=α i A i(T w -T rm ) (5)

[0063] In the formula, α i is the heat transfer coefficient on the refrigerant side, A i is the inner surface area of ​​the tube, T w is the tube wall temperature, T rm is the average refrigerant temperature.

[0064]

[0065] For the superheated area, the refrigerant side heat transfer coefficient α i,SH Calculated by the Dittus-Boeler heat transfer correlation:

[0066] Nu i =0.023Re 0.8 Pr 0.4 (7)

[0067] In the formula, G r is the refrigerant mass flow density, d i is the inner diameter of the tube.

[0068] When the refrigerant is in a two-phase state, there are two flow patterns in the process of boiling flow in the tube: mist flow and annular flow. The transition of the flow pattern is determined by the critical dryness:

[0069] x cr =7.94[Re vs ×(2.03×10 4 R vs -0.81 ΔT-1)] -0.161 (8)

[0070] In the formula, R evs is the Reynolds number when the gaseous refrigerant flows alone in the tube. cr When , the two-phase refrigerant flow pattern is annular flow, otherwise it is mist flow. The heat transfer coefficient of annular flow in the two-phase region of the evaporator is;

[0071]

[0072] Where Nu is the Nusselt number of the refrigerant; P rl is the Prandtl number of the refrigerant liquid phase; μ v With μ l are the dynamic viscosity coefficients of the refrigerant saturated vapor phase and saturated liquid phase respectively; ρ v and ρ l are the densities of the saturated vapor phase and saturated liquid phase of the refrigerant respectively; C plis the isobaric specific heat capacity of the saturated refrigerant liquid; ΔT is the temperature difference between the refrigerant and the pipe wall.

[0073] The refrigerant gas and liquid in the mist flow are evenly mixed and can be approximated as homogeneous flow. At this time, the refrigerant heat transfer coefficient is:

[0074]

[0075] In the formula, λ v is the thermal conductivity of saturated refrigerant vapor; G m is the mass flow rate of the homogeneous flow of refrigerant; d is the inner diameter of the heat exchange tube.

[0076] Under the actual working conditions of the evaporator, the refrigerant not only absorbs the heat from the air flowing through it, but also absorbs some heat conducted through the pipe wall and other components. Therefore, the heat exchange between the refrigerant side and the air side is not completely equal. In addition, the refrigerant will inevitably contain lubricating oil. When measuring the refrigerant flow rate, the influence of the lubricating oil factor must be considered, resulting in the heat exchange obtained by multiplying the flow rate by the enthalpy difference being larger than the actual heat exchange rate. Considering the above factors and based on a large amount of experimental data, the following relationship is concluded between the two:

[0077] Q a =γQ r (13)

[0078] In the formula, the value of γ depends on the specific situation. It can generally be taken as 0.9, and 0.85 is taken in this simulation model.

[0079] Micro-element heat transfer equation:

[0080]

[0081] Wall length:

[0082]

[0083] Refrigerant side pressure drop:

[0084]

[0085] Air side pressure drop:

[0086]

[0087] Where Q, h, T and m are heat transfer, enthalpy, temperature and mass flow rate respectively; A i is the heat exchange area on the refrigerant side; A o is the total surface area on the air side; A c is the cross-sectional area of ​​air flow; σ is the ratio of the minimum flow area to the windward area; G c For the definition in A cThe air mass flux on the tube; the subscript a represents the air side, r represents the refrigerant side, i represents the inside of the tube (refrigerant side), and in and out represent the inlet and outlet, respectively.

[0088] Mass transfer coefficient h d , calculated as follows:

[0089]

[0090] Where Le is the Lewis number, R a and c p,a are the air side thermal resistance and air specific heat capacity respectively.

[0091] By integrating equation (4), the humidity content of the air at the outlet of the microelement can be derived:

[0092]

[0093] U is the total heat transfer coefficient based on the heat exchange area on the refrigerant side, and the calculation formula is:

[0094]

[0095] In the formula, α i is the heat transfer coefficient of the refrigerant side surface; α o is the heat transfer coefficient of the air side surface; R w A is the thermal resistance of the tube wall (including fins); i / A o is the ratio of the heat exchange area inside and outside the evaporator tube. For each infinitesimal element, it can be considered that A i / A o They are equal to the ratio of the total heat exchange area inside and outside the evaporator tube.

[0096] The following main assumptions are used when modeling the condenser: (1) The condenser is a countercurrent heat exchanger; (2) The thermal resistance of the tube wall is negligible; (3) The actual refrigerant flow in the tube is a complex phase-separated flow, which is simplified to a one-dimensional homogeneous flow model to increase the calculation speed; (4) The flow of air outside the tube is also considered as a one-dimensional flow.

[0097] In the process of condenser modeling, it is divided into three phase zones (superheat zone, two zones, and subcooling zone) and treated separately. For the single-phase zone, i.e., the superheat zone and the subcooling zone, the micro-element division is evenly divided according to the temperature drop on the refrigerant side; for the two-phase zone, since the temperature remains unchanged, the heat exchange is manifested in the change of enthalpy value, so the micro-element division can be evenly divided according to the enthalpy difference of the refrigerant in the two-phase zone.

[0098] The following specific governing equations are used when modeling the condenser:

[0099] Air side energy equation:

[0100] Qa =m a (h a,out -h a,in )(twenty four)

[0101] Refrigerant side energy equation:

[0102] Q r =m r (h r,in -h r,out )(25)

[0103] The energy balance equation of the refrigerant in the condenser and the correlation equation of the heat transfer coefficient in the single-phase zone (including the superheat zone and the subcooling zone) refer to equations (5) and (7) respectively. Unlike the evaporator, the refrigerant flow pattern in the horizontal tube of the condenser can be divided into three forms according to its mass flow rate: mist flow, annular flow and wavy flow. The transition criteria between different flow patterns are usually described by the Froude number Fr and the Weber number We.

[0104] The heat transfer coefficients of annular flow and mist flow in the two-phase region of the condenser are obtained by equations (9) and (10) respectively. For wavy flow, the heat transfer coefficient correlation equation can be expressed as:

[0105]

[0106] Energy balance equation on both sides:

[0107] Q a =ξQ r (27)

[0108] Micro-element heat transfer equation:

[0109]

[0110] Wall length:

[0111]

[0112] Where Q, h, T and m are heat transfer, enthalpy, temperature and mass flow rate respectively; the heat leakage coefficient ξ is taken as 0.85.

[0113] U is the total heat transfer coefficient based on the heat exchange area on the refrigerant side, which satisfies the following relationship:

[0114]

[0115] In the formula, α i is the heat transfer coefficient of the refrigerant side surface; α o is the heat transfer coefficient of the air side surface; R w A is the thermal resistance of the tube wall (including fins); i / A ois the ratio of the heat exchange area inside and outside the evaporator tube. For each infinitesimal element, A i / A o They are equal to the ratio of the total heat exchange area inside and outside the evaporator tube.

[0116] Specific embodiment 2 is in low temperature constant humidity control mode, at which time the air conditioning system operates in medium and low temperature mode. The refrigerant is R410A. The difference from specific embodiment 1 is that the electronic expansion valve 11 of the branch where the reheater 9 is located in specific embodiment 2 is dynamically adjusted within a large opening range, mainly used to compensate for the heat loss of the treated air during the cooling and dehumidification process, while retaining the function of accurately adjusting the outlet temperature of the treated gas.

[0117] In the specific implementation, the operating conditions of the air conditioning system when the decoupling economizer 5 is not introduced are: the evaporation pressure of the refrigerant after throttling on the first thermal expansion valve 8 side is 0.8MPa, the evaporation pressure of the refrigerant after throttling on the electronic expansion valve 11 side is 0.8MPa, and the condensation pressure is 2MPa; the suction superheat of the compressor 1 inlet is 5K, the liquid subcooling degree of the reheater 9 outlet is 1K, and the liquid subcooling degree of the second heat exchanger 4 outlet is 2K; at this time, the inlet R410A enthalpy of the reheater 9 and the second heat exchanger 4 is 452.60kJ / kg, and the inlet R410A enthalpy of the first heat exchanger 13 is 249.97kJ / kg. The mass flow rate of the refrigerant in the main road is 0.01389kg / s, and the two refrigerant flow rates of the branch where the first thermal expansion valve 8 is located and the branch where the electronic expansion valve 11 is located account for 0.3 and 0.7 respectively. The temperature and relative humidity of the treated air inlet are 15° C., 40% RH, and the flow rate is 3 m / s; the air velocity on the second heat exchanger 4 side is 1 m / s.

[0118] Under the above working conditions, taking the finned heat exchanger as an example, the fin type is flat fins, the corresponding form is square fin tubes, the fin spacing is 0.0018m, and the fin thickness is 0.00012m; according to the mass flow rate, evaporation pressure, inlet enthalpy, outlet superheat and inlet parameters of the refrigerant on the air side, it can be solved that the length of a single tube of the first heat exchanger 13 is 0.3370m, 2 branch flow channels, 5 rows of tubes are set, and each row of tubes has 6 single tubes. Among them, the inner diameter of the tube is 0.009m, the outer diameter of the tube is 0.01m, the tube spacing is 0.027m, and the row spacing is 0.022m. According to the mass flow rate, condensation pressure, inlet enthalpy, outlet supercooling and inlet parameters of the refrigerant on the air side, it can be solved that the length of a single tube of the reheater 9 is 0.2211m, 3 branch flow channels, 3 rows of tubes are set, and each row of tubes has 6 single tubes. Among them, the inner diameter of the tube is 0.009m, the outer diameter of the tube is 0.0095m, the distance between tubes is 0.020m, and the distance between rows is 0.0217m. According to the mass flow rate, condensing pressure, inlet enthalpy, outlet subcooling and inlet parameters of the air side of the refrigerant, it can also be solved that the length of the single tube of the second heat exchanger 4 is 0.2029m, 3 branch flow channels, 3 rows of tubes are set, and each row of tubes has 6 single tubes. Among them, the inner diameter of the tube is 0.009m, the outer diameter of the tube is 0.0095m, the distance between tubes is 0.020m, and the distance between rows is 0.0217m.

[0119] Furthermore, the outlet state of the air treated by the first heat exchanger 13 is used as the inlet condition of the reheater 9. According to simulation calculation, under the above heat exchanger specifications, the air to be treated (temperature 15°C, relative humidity 40%RH, flow rate 3m / s) is treated by the first heat exchanger 13, and its outlet temperature is 9.82°C and relative humidity is 56.21%RH; and after being heated by the reheater 9, its outlet temperature is 16.43°C and relative humidity is 36.29%RH.

[0120] In the specific implementation, the operating conditions of the air conditioning system after the decoupling economizer 5 is introduced: the refrigerant evaporation pressure after throttling on the first thermal expansion valve 8 side, the refrigerant evaporation pressure after throttling on the electronic expansion valve 11 side, the subcooling degree of the liquid at the outlet of the reheater 9, the condensing pressure, the proportion of the two refrigerant flow rates of the branch where the first thermal expansion valve 8 is located and the branch where the electronic expansion valve 11 is located, and the inlet parameters of the processed air side are completely consistent with the above-mentioned when the decoupling economizer 5 is not introduced. After the decoupling economizer 5 acts, the ratio of the refrigerant liquid and the refrigerant vapor in which heat exchange occurs will change, the subcooling degree of the refrigerant liquid will increase, and the superheat degree of the refrigerant vapor will decrease. Under the working conditions of this specific implementation method, the subcooling degree of the refrigerant liquid is 10K, and the superheat degree of the compressor inlet suction is 6K. At this time, the inlet R410A enthalpy of the reheater 9 and the second heat exchanger 4 is 453.85kJ / kg, and the inlet R410A enthalpy of the first heat exchanger 13 is 245.86kJ / kg.

[0121] Furthermore, the outlet state of the air treated by the first heat exchanger 13 is used as the inlet condition of the reheater 9. According to simulation calculation, under the aforementioned heat exchanger specifications, the aforementioned air to be treated (temperature 15°C, relative humidity 40%RH, flow rate 3m / s) is treated by the first heat exchanger 13, and its outlet temperature is 9.76°C and relative humidity is 56.44%RH; and then after being heated by the reheater 9, its outlet temperature is 16.40°C and relative humidity is 36.57%RH.

[0122] By comparing the temperature and humidity differences of the treated air after being treated by each heat exchanger before and after the introduction of the decoupling economizer 5, it can be seen that after the decoupling economizer 5 is introduced into the air conditioning system, the treated air can reach a lower temperature after heat exchange in the first heat exchanger 13, and has a better dehumidification effect; since the inlet temperature of the air flowing into the reheater 9 is relatively low, the outlet temperature of the air is also relatively low. In practical applications, in order to ensure the temperature and humidity requirements of the air outlet, the required cooling capacity is the same when a certain amount of air is dehumidified under the same inlet conditions. In order to meet the same processing requirements as the original system, the circulation flow of the refrigerant in the system after the introduction of the decoupling economizer 5 needs to be reduced accordingly, which is conducive to reducing the operating power consumption of the entire system. From the perspective of system performance, after the introduction of the decoupling economizer 5, the comprehensive energy efficiency ratio of the system is improved by 0.58%. In addition, when the outlet air temperature is too low, the opening of the electronic expansion valve 11 can be further increased, so that the proportion of the refrigerant flow on the reheater 9 side to the total trunk flow increases, thereby further strengthening the recovery of condensation heat.

[0123] Specific implementation method 3, in specific implementation, as Figure 2 As shown, the air conditioning system is in the medium and high temperature mode. The No. 1 air valve 19 leading to the outside is closed, and the No. 2 air valve 20 leading to the inside is opened; at the same time, the No. 3 air valve 21 leading to the inside is closed, and the No. 4 air valve 22 leading to the outside is opened. The air to be treated will pass through the first heat exchanger 13 and the reheater 9 successively, and the precise temperature rise control of the output air is realized under the continuous two-stage high-efficiency heating control mechanism.

[0124] In specific implementation, after the refrigerant R410A absorbs heat and turns into gas in the second heat exchanger 4 (used as an evaporator), it flows into the four-way reversing valve 3, and after being adjusted, it passes through the gas-liquid separator 16 and enters the compressor 1 in a completely gaseous state. It is then compressed into a high-temperature and high-pressure gaseous refrigerant, and after passing through the oil separator 2, it is divided into two streams, which respectively enter the branch where the first heat exchanger 13 (used as a condenser) is located and the branch where the reheater 9 is located. For the stream entering the branch where the first heat exchanger 13 is located, the high-temperature and high-pressure gaseous refrigerant first enters the four-way reversing valve 3. After being adjusted, the refrigerant flows into the first heat exchanger 13 through the fourth electric three-way valve 15 and the third electric three-way valve 14, releasing the condensation heat. The cooled refrigerant then passes through the second electric three-way valve 12 and the third drying filter 17 and flows to the second thermal expansion valve 18. After throttling, the pressure and temperature of the refrigerant are greatly reduced, and then merge with the low-temperature and low-pressure refrigerant split stream from the branch where the reheater 9 is located. This is the confluence point of the two refrigerants, and the separation point of the two refrigerants is after the oil separator 2, and is divided into the branch where the first heat exchanger 13 is located and the branch where the reheater 9 is located. For the branch stream entering the branch where the reheater 9 is located, the heat is first released in the reheater 9, and then flows to the electronic expansion valve 11 through the second dryer 10. After throttling, the pressure and temperature of the refrigerant are greatly reduced, and then it merges with the low-temperature and low-pressure refrigerant branch stream from the branch where the first heat exchanger 13 is located. The merged low-temperature and low-pressure refrigerant stream enters the decoupling economizer 5 through the first electric three-way valve 6. From the outlet of the decoupling economizer 5 to the inlet of the second heat exchanger 4, the refrigerant absorbs heat from the environment while flowing, unloading part of the cold capacity and weakening its cooling capacity in the second heat exchanger 4. The refrigerant evaporates and absorbs heat in the second heat exchanger 4. If it works in a cycle, the basic core functions in the medium and high temperature mode can be realized.

[0125] In the specific implementation, R410A is selected as the refrigerant, and the operating conditions of the air conditioning system are: the evaporation pressure of the refrigerant after throttling on the second thermal expansion valve 18 side is 0.8MPa, the evaporation pressure of the refrigerant after throttling on the electronic expansion valve 11 side is 0.8MPa, and the condensation pressure is 2MPa; the suction superheat of the compressor 1 inlet is 5K, the liquid subcooling degree of the reheater 9 outlet is 1K, and the liquid subcooling degree of the first heat exchanger 13 outlet is 2K; at this time, the inlet R410A enthalpy values ​​of the reheater 9 and the first heat exchanger 13 are both 452.60kJ / kg, and the inlet R410A enthalpy value of the decoupling economizer 5 is 249.97kJ / kg. The mass flow rate of the refrigerant in the main road is 0.01389kg / s, and the two refrigerant flows of the branch where the second thermal expansion valve 18 is located and the branch where the electronic expansion valve 11 is located account for 0.3:0.7.

[0126] Furthermore, the outlet state of the air treated by the first heat exchanger 13 is used as the inlet condition of the reheater 9. According to numerical simulation calculation, under the aforementioned heat exchanger specifications, the air to be treated (temperature 15°C, relative humidity 40%RH, flow rate 3m / s) is treated by the first heat exchanger 13, and its outlet temperature is 18.34°C and the relative humidity is 32.33%RH; and then after being heated by the reheater 9, its outlet temperature is 22.92°C (increased by 7.92°C) and the relative humidity is 24.39%RH. Compared with Specific Embodiment 2, the outlet temperature of the treated air in Specific Embodiment 3 is further increased by 6.49°C. Analyzing the thermodynamic parameters of the refrigerant, the specific enthalpy values ​​of the refrigerant at the outlets of the first heat exchanger 13 and the reheater 9 are 229.79kJ / kg and 310.42kJ / kg, respectively, and the theoretical specific work of the compressor is 25.75kJ / kg. At this time, combined with the specific enthalpy value (452.60 kJ / kg) at the inlet of the first heat exchanger 13 and the reheater 9 and the flow distribution ratio in the two branches (0.3:0.7), it can be calculated that the theoretical comprehensive energy efficiency ratio of the system is 6.46.

[0127] Furthermore, by electrically adjusting the opening of the sub-expansion valve 11, the flow distribution between the first heat exchanger 13 and the reheater 9 can be dynamically adjusted, thereby obtaining a larger and more flexible temperature rise effect. Taking the ratio of the refrigerant flow of the second thermal expansion valve 18 branch and the electronic expansion valve 6 branch to the total flow of the trunk line as 0.5:0.5 as an example, the aforementioned air to be treated (temperature 15°C, relative humidity 40%RH, flow rate 3m / s) passes through the first heat exchanger 13, and its outlet temperature is 20.12°C and relative humidity is 28.96%RH; and then after being heated by the reheater 9, its outlet temperature is 24.03°C and relative humidity is 22.82%RH. Compared with the two-branch refrigerant flow distribution ratio (0.3:0.7) scheme described in the previous paragraph, the temperature rise is increased by 1.11°C here. Compared with the working condition when the decoupling economizer 5 is not introduced in the specific implementation mode 2, the relative temperature rise change rate of the air conditioning system as a whole is more significant in the specific implementation mode 3 (9.03℃: 1.43℃). Analyzing the changes in the thermodynamic parameters of the refrigerant, the specific enthalpy values ​​of the refrigerant at the outlets of the first heat exchanger 13 and the reheater 9 are 247.75kJ / kg and 284.24kJ / kg respectively, and the theoretical specific work of the compressor is 25.75kJ / kg. At this time, combined with the specific enthalpy values ​​(452.60kJ / kg) at the inlet of the first heat exchanger 13 and the reheater 9 and the flow distribution ratio (0.5:0.5) in the two branches, it is calculated that the theoretical comprehensive energy efficiency ratio of the system is 7.25. Compared with the two-branch refrigerant flow distribution ratio (0.3:0.7) scheme described in the previous paragraph, the theoretical comprehensive heating energy efficiency ratio of the system is improved by 12.2%.

[0128] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system, characterized in that: It includes a precision air conditioning system, an air handling unit and a control unit. The control unit is connected to the precision air conditioning system and the air handling unit. The precision air conditioning system is connected to the air handling unit. The precision air conditioning system provides the required cooling or heating for the air handling unit.

2. The energy-saving temperature and humidity decoupling control hot and cold dual-function air conditioning system according to claim 1, characterized in that: The air handling unit comprises a first heat exchanger (13), a second heat exchanger (4) and a reheater (9); the precision air conditioning system comprises a compressor (1), an oil separator (2), a decoupling economizer (5), a first drying filter (7), a second drying filter (10), a gas-liquid separator (16), a third drying filter (17), a first non-return valve, a second non-return valve and a third non-return valve; the first heat exchanger (13) is connected to the decoupling economizer (5) via a third electric three-way valve (14); the decoupling economizer (5) is connected to the third electric three-way valve (14) and a four-way reversing valve (3) via a fourth electric three-way valve (15); the decoupling economizer (5) is connected to the second heat exchanger (4) and the first electric three-way valve (6); the second heat exchanger (4) is connected to the four-way reversing valve (3); the four-way reversing valve (3) is connected to the fourth electric three-way valve (15 ... The valve (3) is connected to the gas-liquid separator (16), the compressor (1), and the oil separator (2); the oil separator (2) is connected to the four-way reversing valve (3) and the reheater (9); the reheater (9) is connected to the second filter dryer (10), the electronic expansion valve (11), the first check valve, the second check valve, the first thermal expansion valve (8), and the first filter dryer (7); the first electric three-way valve (6) is connected to the line between the second check valve and the first check valve; the line between the second check valve and the first check valve is connected to the first heat exchanger (13) through the second electric three-way valve (12); the second electric three-way valve (12) is connected to the line between the electronic expansion valve (11) and the first thermal expansion valve (8) through the third filter dryer (17), the second thermal expansion valve (18), and the third check valve; A first air supply regulator (23), a first primary air filter (24), a first medium-efficiency air filter (25), a first heat exchanger (13), and a first fan (26) are arranged on a parallel branch of the air duct. The branch is connected to the reheater (9) and the second fan (27) through a No. 2 air valve (20), and is connected to the outside through a No. 1 air valve (19). A second air supply regulator (28), a second primary air filter (29), a second medium-efficiency air filter (30), a second heat exchanger (4), and a third fan (31) are arranged on another parallel branch of the air duct. The branch is connected to the reheater (9) and the second fan (27) through a No. 3 air valve (21), and is connected to the outside through a No. 4 air valve (22).

3. A control method for an energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system as claimed in claim 2, characterized in that: The steps include: S1, the air conditioning system switches the operating mode, the operating modes include medium-low temperature mode and medium-high temperature mode; S2, regulating the parallel air ducts of the air conditioning system through the air valve matrix; S3, the decoupling economizer (5) of the air conditioning system performs decoupling control; S4. The air conditioning system operates in any of the five operating conditions: pure cooling control, low temperature constant humidity control, medium temperature constant humidity control, high temperature constant humidity control, and pure heating control; S5. Control the air handling unit to perform air volume regulation, air filtration, surface cooling and reheating.

4. The control method of the energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system as claimed in claim 3, characterized in that: In step S1, the air conditioning system is in a medium to low temperature mode: The first heat exchanger (13) is an evaporator for cooling and dehumidifying the air, the second heat exchanger (4) is a condenser for preliminarily heating the air, a reheater (9) is arranged at the end of the air handling unit for reheating the treated air, and the decoupling economizer (5) is used to realize heat exchange between the relatively low-temperature refrigerant vapor flowing through the first heat exchanger (13) and the relatively high-temperature refrigerant liquid of the second heat exchanger (4), so that the liquid is supercooled and the vapor is superheated; The refrigerant absorbs heat and undergoes a phase change in the first heat exchanger (13), leaves the first heat exchanger (13) in a vapor state, passes through the third electric three-way valve (14), and flows into the decoupling economizer (5); flows out of the decoupling economizer (5) in a superheated vapor state, passes through the fourth electric three-way valve (15), and flows into the four-way reversing valve (3); after being adjusted by the four-way reversing valve (3), passes through the gas-liquid separator (16), and enters the compressor (1) in a completely gaseous state; and is then compressed into a high-temperature and high-pressure gaseous refrigerant, and after passing through the oil separator (2), is divided into two streams and enters the compressor (1) and the oil separator (2). The refrigerant enters the branch where the second heat exchanger (4) is located and the branch where the reheater (9) is located; for the flow stream entering the branch where the second heat exchanger (4) is located, the high-temperature and high-pressure gaseous refrigerant first enters the four-way reversing valve (3); after being adjusted by the four-way reversing valve (3), it enters the second heat exchanger (4), releases the condensation heat into the air duct, and the refrigerant is converted from a gas phase to a liquid phase; then it flows into the decoupling economizer (5) to exchange heat with the lower temperature refrigerant vapor from the first heat exchanger (13) serving as a condenser; the subcooled refrigerant after being cooled passes through the first an electric three-way valve (6), a first drying filter (7), and flows to a first thermal expansion valve (8); under the throttling effect of the first thermal expansion valve (8), the pressure and temperature of the refrigerant are greatly reduced, and then merge with the low-temperature and low-pressure refrigerant branch from the branch where the reheater (9) is located; this is the confluence point of the two refrigerants; and the separation point of the two refrigerants is after the oil separator (2), and they enter the branch where the second heat exchanger (4) is located and the branch where the reheater (9) is located respectively; for the branch entering the branch where the reheater (9) is located , first releases heat in the reheater (9) to fine-tune the quality of the output air, then passes through the second drying filter (10) and flows to the electronic expansion valve (11); under the throttling effect of the electronic expansion valve (11), the pressure and temperature of the refrigerant are greatly reduced, and then merges with the low-temperature and low-pressure refrigerant branch from the branch where the second heat exchanger (4) is located; the merged low-temperature and low-pressure gas-liquid two-phase refrigerant flow passes through the second electric three-way valve (12) and re-enters the first heat exchanger (13), where it evaporates and absorbs heat, and the cycle works in this way.

5. The control method of the energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system according to claim 4, characterized in that: In step S1, in the medium-high temperature mode of the air conditioning system, the first heat exchanger (13) is a condenser for preliminarily heating the air; the second heat exchanger (4) is an evaporator for cooling and dehumidifying the air; A reheater (9) is provided at the end of the air handling unit for reheating the treated air, and a decoupling economizer (5) unloads the coldness of the gas-liquid two-phase refrigerant to flow into the second heat exchanger (4) in the form of air cooling; The refrigerant evaporates and absorbs heat in the second heat exchanger (4), and then changes into a gaseous state and flows into the four-way reversing valve (3). After being adjusted, it passes through the gas-liquid separator (16) and enters the compressor (1) in a completely gaseous state. It is then compressed into a high-temperature and high-pressure gaseous refrigerant, and after passing through the oil separator (2), it is divided into two streams, which respectively enter the branch where the first heat exchanger (13) is located and the branch where the reheater (9) is located. For the stream entering the branch where the first heat exchanger (13) is located, the high-temperature and high-pressure gaseous refrigerant The refrigerant first enters the four-way reversing valve (3); after being adjusted by the four-way reversing valve (3), the refrigerant is adjusted by the third electric three-way valve (14) and the fourth electric three-way valve (15), bypassing the decoupling economizer (5), and flows directly into the first heat exchanger (13); after the high-temperature and high-pressure refrigerant releases the condensation heat in the first heat exchanger (13), it flows through the second electric three-way valve (12) and the third drying filter (17) to the second thermal expansion valve (18); after the second thermal expansion valve (1 8), the pressure and temperature of the refrigerant are greatly reduced, and then merge with the low-temperature and low-pressure refrigerant branch from the branch where the reheater (9) is located; this is the confluence point of the two refrigerants; and as mentioned above, the separation point of the two refrigerants is after the oil separator (2), and is divided into the branch where the first heat exchanger (13) is located and the branch where the reheater (9) is located; for the branch entering the branch where the reheater (9) is located, the heat is first released in the reheater (9) and then heated to room temperature. The temperature of the output air is further increased to improve the heating capacity of the system; then, the refrigerant flows through the second dryer (10) to the electronic expansion valve (11); under the throttling effect of the electronic expansion valve (11), the pressure and temperature of the refrigerant are greatly reduced, and then merges with the low-temperature and low-pressure refrigerant flow stream from the branch where the first heat exchanger (13) is located; the merged low-temperature and low-pressure gas-liquid two-phase refrigerant flow stream passes through the first electric three-way valve (6) and enters the decoupling economizer (5); After being unloaded by the decoupling economizer, the refrigerant returns to the second heat exchanger (4) to complete evaporation and heat absorption, thus completing the cycle.

6. The control method of the energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system according to claim 5, characterized in that: In step S2, the parallel design of the air duct of the air conditioning system is adjusted through an air valve matrix, and with the help of a corresponding switch combination scheme of air valve No. 1 (19), air valve No. 2 (20), air valve No. 3 (21) and air valve No. 4 (22), the air in the two branches flowing through the evaporator and the condenser is mixed according to an optimal ratio; the heat exchanger on the evaporator side is responsible for independently adjusting the relative humidity of the gas, and the heat exchanger on the condenser side is responsible for independently controlling the temperature rise of the gas.

7. The control method of the energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system according to claim 6, characterized in that: In step S3, the decoupling economizer (5) of the air-conditioning system plays the role of an economizer when the air-conditioning system is in a medium-low temperature mode, and a heat exchange process between cold and hot fluids is carried out in the decoupling economizer (5), so that the liquid of the refrigerant is supercooled and the vapor is superheated; when the air-conditioning system is in a high temperature mode, it plays the role of a decoupler to unload the cold capacity of the low-temperature and low-pressure refrigerant; at this time, in order to achieve a specific dehumidification effect, the system needs to increase the circulation flow rate of the refrigerant, correspondingly increase the refrigerant flow rate, enhance the heat exchange efficiency on the condenser side and the reheater side, and further increase the outlet temperature of the treated air.

8. The control method of the energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system according to claim 7, characterized in that: In step S4, the air conditioning system flexibly switches to corresponding control strategies according to pure cooling control requirements, low temperature constant humidity control requirements, medium temperature constant humidity control requirements, high temperature constant humidity control requirements and pure heating control requirements.

9. The control method of the energy-saving temperature and humidity decoupling control cooling and heating dual-function air conditioning system according to claim 8, characterized in that: In the step S5, The air volume adjustment section controls the air handling volume by the cross-sectional flux of the fresh air inlet opening; The filter section first performs primary filtration on the incoming fresh air, and then performs medium filtration; The surface cooling section has low-temperature and low-pressure refrigerant flowing through it, which is used to cool and dehumidify the air passing through it; The reheating section uses a reheater (9) to recycle the heat released by the refrigerant during the condensation process to achieve heating of the air.

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