Multi-split central air conditioning system for simultaneous cooling and heating

Abstract

The present invention relates to a multi-split central air conditioning system for simultaneous cooling and heating, comprising a condensation module, a plurality of indoor fan coil units, a high-pressure circulation tube, a medium-pressure circulation tube, a low-pressure circulation tube, and an evaporation module. The indoor fan coil units are connected to the high-pressure circulation tube by means of a first branch tube, to the low-pressure circulation tube by means of a second branch tube, and to the medium-pressure circulation tube by means of a third branch tube, and a solenoid valve is provided on each of the first branch tube and the second branch tube. The beneficial effects are: when heating a local area in the summer and cooling a local room in the winter, refrigerant is circulated by means of solenoid valve switching and a medium-pressure circulation tube such that the multi-split central air conditioning system has multiple working modes (independent cooling / independent heating / simultaneous partial cooling and partial heating), thereby improving the diversity of the overall operation conditions of the air conditioning system without adding a complex refrigerant switching piping. The condensation module and the evaporation module can also be used as a balancer of the system to ensure efficient and stable operation of the system.

Description

A multi-split central air-conditioning system that performs both cooling and heating Technical Field

[0001] The present invention relates to the field of air conditioning, and in particular to a multi-connected central air conditioning system that performs cooling and heating simultaneously. Background Art

[0002] Central air conditioning uses a refrigeration cycle to cool or heat indoor spaces, providing unified cooling in the summer and heating in the winter. This is the basic function of air conditioning. However, it also presents a problem: once cooling is turned on, all air conditioners are in cooling mode, and once heating is turned on, all air conditioners are in heating mode. During transitional seasons, such as in southern China where the weather fluctuates between cold and hot, different groups of people have different thermal comfort needs. For example, middle-aged and young people with better physiques may feel a bit hot and require cooling, while the elderly and children may feel cold and require heating. Currently, most common VRF units on the market can only operate in a single cooling or heating mode. If simultaneous cooling and heating are required in different rooms within a single system, two separate air conditioning systems must be installed, increasing construction costs.

[0003] As energy shortages become increasingly prominent, China has proposed dual carbon goals as a national development strategy. Energy conservation, environmental protection, and low carbon emissions will become the mainstream trends in today's society, guiding the development of technological applications across all industries. Among future refrigerant options, the natural refrigerant CO2, with its high pressure differential, low viscosity, stable chemical properties, and excellent thermal properties, has once again attracted the attention of refrigeration industry technicians. In recent years, CO2-related products have gradually increased their market share.

[0004] Therefore, the motivation for the invention is to provide a multi-split central air-conditioning system that can simultaneously cool some independent spaces and heat other independent spaces using a set of air-conditioning systems; a system that can easily switch between cooling and heating and can perform both cooling and heating.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a multi-split central air-conditioning system that can simultaneously cool some independent spaces and heat other independent spaces using a set of air-conditioning systems; a multi-split central air-conditioning system that can easily switch between cooling and heating and can simultaneously cool and heat is the motivation for the development of the present invention.

[0007] The present invention provides a technical solution as follows:

[0008] A multi-split central air-conditioning system for simultaneous cooling and heating includes a condensing module, multiple indoor fan coil units, a high-pressure circulation pipe, a medium-pressure circulation pipe, a low-pressure circulation pipe and an evaporation module. The condensing module includes a compressor, a condenser and a liquid storage tank connected in sequence. The high-pressure circulation pipe is connected to the exhaust end of the compressor; the medium-pressure circulation pipe is connected to the liquid storage tank and the evaporation module; the low-pressure circulation pipe is connected to the suction end of the compressor and the evaporation module; the indoor fan coil unit is connected to the high-pressure circulation pipe through a first branch pipe, connected to the low-pressure circulation pipe through a second branch pipe, and connected to the medium-pressure circulation pipe through a third branch pipe. A first solenoid valve is provided on the first branch pipe, and a second solenoid valve is provided on the second branch pipe.

[0009] Furthermore, an electronic expansion valve is provided on the third branch pipe.

[0010] Furthermore, when a portion of the indoor fan coil units need cooling, the first solenoid valve of the cooling indoor fan coil units is closed, and the refrigerant in the storage tank passes through the medium-pressure flow pipe, the electronic expansion valve, the indoor fan coil units, the second solenoid valve, and the low-pressure flow pipe in sequence to complete the refrigeration cycle;

[0011] When another part of the indoor fan coil needs to heat, the second solenoid valve of the heating indoor fan coil is closed, and the high-temperature refrigerant at the exhaust end of the compressor passes through the high-pressure circulation pipe, the first solenoid valve, the indoor fan coil, the electronic expansion valve, the evaporation module, and the low-pressure circulation pipe in sequence to complete the heating cycle.

[0012] Furthermore, a temperature sensor and a pressure sensor are provided at the exhaust end of the compressor; a temperature sensor is provided at the suction end of the compressor; a temperature sensor is provided on the pipe between the condenser and the liquid storage tank; a solenoid valve and a capillary tube are also provided on the pipe between the liquid storage tank and the compressor; temperature sensors are provided at the inlet and outlet ends of the indoor fan coil; and pressure sensors are respectively provided on the medium-pressure circulation pipe and the low-pressure circulation pipe.

[0013] Furthermore, a first constant pressure valve is provided on the pipeline connecting the compressor exhaust end of the condensing module and the condenser, and a second constant pressure valve is provided on the pipeline between the condenser and the liquid storage tank.

[0014] Furthermore, the central air conditioning system also includes floor heating pipes and / or domestic hot water pipes;

[0015] The floor heating pipes are connected to the high-pressure circulation pipe and the medium-pressure circulation pipe respectively. An electronic expansion valve is provided on the connecting pipe between the floor heating pipe and the medium-pressure circulation pipe, and a manual stop valve is provided on the connecting pipe between the floor heating pipe and the high-pressure circulation pipe;

[0016] The domestic hot water pipe is connected to the high-pressure circulation pipe and the medium-pressure circulation pipe respectively. An electronic expansion valve is provided on the connecting pipe between the domestic hot water pipe and the medium-pressure circulation pipe, and a manual stop valve is provided on the connecting pipe between the domestic hot water pipe and the high-pressure circulation pipe.

[0017] Furthermore, the evaporation module is a freeze-thaw cycle evaporator, which includes an infrared collector, a heat collecting end, an energy tank and a heat exchanger. The energy tank stores freeze-thaw medium, the heat collecting end and the heat exchanger are arranged in the energy tank, and the two ends of the heat exchanger are respectively connected to the refrigerant circulation pipeline.

[0018] Furthermore, the medium-pressure circulation pipe is connected to the infrared heat collecting plate, and a fourth control valve is provided between the medium-pressure circulation pipe and the infrared heat collecting plate; the infrared heat collecting plate is connected to the heat collecting end, and the other end of the heat collecting end is connected to the low-pressure circulation pipe; the high-pressure circulation pipe is connected to the first control valve, and the first control valve is respectively connected to the heat exchanger and the second control valve, the other end of the second control valve is connected to the low-pressure circulation pipe, the other end of the heat exchanger is connected to the third control valve, and the third control valve is connected to the medium-pressure circulation pipe.

[0019] Furthermore, the refrigerant is selected from Freon, ammonia or carbon dioxide.

[0020] Furthermore, carbon dioxide is selected as the single-circulation working fluid as the refrigerant, and the condenser is a flash evaporator. The flash evaporator includes a closed shell, a negative pressure fan and a heat exchange unit. The negative pressure fan is arranged on the top of the closed shell to form a negative pressure in the closed shell; multiple heat exchange units are arranged in a stacked manner in the closed shell, and the heat exchange unit includes a water atomizer, multiple rows of coils for circulating the refrigerant and fins for fixing the multiple rows of coils. The multiple rows of coils and the fins are fixed by a fixing frame, and carbon dioxide flows in from the inlet end and is discharged from the outlet end; the water atomizer is connected to a water source to atomize water.

[0021] The implementation of the present invention includes the following technical effects:

[0022] The entire central air conditioning system of the present invention uses a condenser to dissipate heat and an infrared radiation collector to absorb heat. When heating a local area in summer or cooling a local room in winter, the refrigerant circulates through solenoid valve switching and medium-pressure circulation pipes. This enables the multi-connected central air conditioning system of the present invention to have multiple operating modes (single cooling / single heating / simultaneous partial cooling and partial heating), thereby increasing the diversity of the overall operating conditions of the multi-connected air conditioning system without adding complex refrigerant switching piping. The system of the present invention can simultaneously cool and heat, addressing the different comfort needs of different groups of people. In one system, different indoor units can achieve separate cooling and heating.

[0023] The condensing module and the evaporating module can also serve as the balancer of the entire air-conditioning system, balancing the operating pressure and other parameters during the operation of the air-conditioning, ensuring the efficient and stable operation of the system, which is also an important effect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a schematic diagram of a multi-split central air-conditioning system that performs simultaneous cooling and heating according to an embodiment of the present invention.

[0025] Figure 2 is a schematic diagram of the flash evaporator structure.

[0026] In the figure: 1. Condensing module; 10. Compressor; 11. Condenser; 110. Enclosed shell; 111. Negative pressure fan; 112. Heat exchange unit; 113. Water atomizer; 12. Liquid storage tank; 13. Temperature sensor; 14. First constant pressure valve; 15. Second constant pressure valve; 16. Pressure sensor; 17. Capillary tube; 2. Indoor fan coil; 20. First solenoid valve; 21. Second solenoid valve; 22. Electronic expansion valve; 23. First branch pipe; 24. Second branch pipe; 25. Third branch pipe; 3. High-pressure circulation pipe; 4. Medium-pressure circulation pipe; 5. Low-pressure circulation pipe; 6. Evaporation module; 60. Infrared collector; 61. Collecting end; 62. Energy tank; 63. Heat exchanger; 64. First control valve; 65. Second control valve; 66. Third control valve; 67. Fourth control valve; 7. Floor heating pipe; 8. Domestic hot water pipe; 9. Manual stop valve. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below with reference to embodiments and drawings. It should be noted that the described embodiments are only intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0028] As shown in FIG1 , a multi-split central air-conditioning system for simultaneous cooling and heating provided in this embodiment includes a condensing module 1, multiple indoor fan coils 2, a high-pressure circulation pipe 3, a medium-pressure circulation pipe 4, a low-pressure circulation pipe 5, and an evaporation module 6. The condensing module 1 includes a compressor 10, a condenser 11, and a liquid storage tank 12 connected in sequence. The high-pressure circulation pipe 3 is connected to the exhaust end of the compressor 10 and the evaporation module 6 to circulate the high-pressure and high-temperature refrigerant discharged from the compressor 10; the medium-pressure circulation pipe 4 is connected to the liquid storage tank 12 and the evaporation module 6 is connected to circulate the medium-pressure refrigerant discharged from multiple indoor fan coil units 2; the low-pressure circulation pipe 5 is connected to the suction end of the compressor 10 and the evaporation module 6, and circulates the low-pressure refrigerant; the indoor fan coil unit 2 is connected to the high-pressure circulation pipe 3 through a first branch pipe 23, is connected to the low-pressure circulation pipe 5 through a second branch pipe 24, and is connected to the medium-pressure circulation pipe 4 through a third branch pipe 25. A first solenoid valve 20 is provided on the first branch pipe 23, a second solenoid valve 21 is provided on the second branch pipe 24, and an electronic expansion valve 22 is provided on the third branch pipe 25.

[0029] As shown in Figure 1, in the same period, when the A1-An indoor fan coil 2 needs cooling and the B1-Bn indoor fan coil 2 needs heating, the first solenoid valve 20 of the A1-An indoor fan coil 2 is closed, and the refrigerant in the liquid storage tank 12 passes through the medium-pressure circulation pipe 4, the electronic expansion valve 22, the indoor fan coil 2, the second solenoid valve 21, and the low-pressure circulation pipe 5 in sequence to complete the refrigeration cycle; at this time, the second solenoid valve 21 of the B1-Bn indoor fan coil 2 is closed, and the high-temperature refrigerant at the exhaust end of the compressor 10 passes through the high-pressure circulation pipe 3, the first solenoid valve 20, the indoor fan coil 2, the electronic expansion valve 22, the evaporation module 6, and the low-pressure circulation pipe 5 in sequence to complete the heating cycle.

[0030] The entire central air-conditioning system of the present invention uses a condenser 11 to dissipate heat and a freeze-thaw cycle evaporator to absorb heat. When heating a local area in summer or cooling a local room in winter, the refrigerant is circulated through solenoid valve switching and a medium-pressure flow pipe 4. This enables the multi-connected central air-conditioning system of the present invention to have multiple operating modes (single cooling / single heating / simultaneous partial cooling and partial heating), thereby increasing the diversity of the overall operating conditions of the multi-connected air-conditioning system without adding complex refrigerant switching piping. The system of the present invention can simultaneously cool and heat, and at the same time, it addresses the different needs of different people for physical comfort. In one system, different indoor units can achieve separate cooling and heating.

[0031] As shown in Figure 1, a first constant pressure valve 14 is installed on the pipe connecting the exhaust end of the compressor 10 of the condensing module 1 to the condenser 11. The constant pressure valve between the compressor 10 and the flash evaporator operates during winter, maintaining a constant exhaust pressure at the pressure corresponding to the maximum COP. In summer, it is fully open to protect the pipe. A second constant pressure valve 15 is installed on the pipe between the condenser 11 and the liquid storage tank 12. The constant pressure valve between the flash evaporator and the liquid storage tank 12 maintains a constant pressure in the liquid storage tank 12 within a certain range, such as 60-65 bar. A temperature sensor 13 and a pressure sensor 16 are installed on the exhaust end of the compressor 10; a temperature sensor 13 is installed on the intake end of the compressor 10; a temperature sensor 13 is installed on the pipe between the condenser 11 and the liquid storage tank 12; and a solenoid valve and capillary tube 17 are also installed on the pipe between the liquid storage tank 12 and the compressor 10. Temperature sensors 13 are installed on both the inlet and outlet ends of the indoor fan coil unit 2. Pressure sensors 16 are installed on the medium-pressure flow pipe 4 and the low-pressure flow pipe 5, respectively. Capillary tube 17 provides throttling and pressure reduction, preventing excessive evaporation of the liquid refrigerant in liquid storage tank 12. Temperature and pressure data from key nodes are collected via temperature sensor 13 and pressure sensor 16, which serve as a basis for controlling the opening of the compressor, fan, solenoid valve, and electronic expansion valve, thereby improving system efficiency.

[0032] As shown in Figure 1, the central air conditioning system also includes floor heating pipes 7, which are connected to the high-pressure circulation pipe 3 and the medium-pressure circulation pipe 4, respectively. The connecting pipe between the floor heating pipe 7 and the medium-pressure circulation pipe 4 is provided with an electronic expansion valve 22, and the connecting pipe between the floor heating pipe 7 and the high-pressure circulation pipe 3 is provided with a manual shut-off valve 9. The central air conditioning system also includes domestic hot water pipes 8, which are connected to the high-pressure circulation pipe 3 and the medium-pressure circulation pipe 4, respectively. The connecting pipe between the domestic hot water pipe 8 and the medium-pressure circulation pipe 4 is provided with an electronic expansion valve 22, and the connecting pipe between the domestic hot water pipe 8 and the high-pressure circulation pipe 3 is provided with a manual shut-off valve 9. When floor heating and domestic hot water production are required, the manual shut-off valve 9 is opened, and the high-temperature refrigerant at the exhaust end of the compressor 10 passes through the high-pressure circulation pipe 3, the manual shut-off valve 9, the floor heating pipe 7 / domestic hot water pipe 8, the electronic expansion valve 22, the evaporation module 6, and the low-pressure circulation pipe 5 in sequence to complete the heating cycle.

[0033] As a preferred embodiment, as shown in FIG1 , the evaporation module is a freeze-thaw cycle evaporator, which includes an infrared heat collector 60, a heat collecting end 61, an energy tank 62, and a heat exchanger 63. The energy tank 62 stores a freeze-thaw medium, and the heat collecting end 61 and the heat exchanger 63 are arranged in the energy tank 62. The two ends of the heat exchanger 63 are respectively connected to the refrigerant circulation pipeline. After the low-temperature refrigerant passes through the heat exchanger 63, it exchanges heat with the freeze-thaw medium. The infrared heat collector 60 stores the absorbed solar energy in the energy tank 62 and extracts heat from the freeze-thaw medium as needed. The freeze-thaw medium is a phase change energy storage material, for example, the freeze-thaw medium is water. It takes a lot of heat to turn 0°C water into 0°C ice. Water is a cheap and environmentally friendly substance, which further reduces costs.

[0034] Specifically, the medium-pressure circulation pipe 4 is connected to the infrared heat collecting plate 60, and a fourth control valve 67 is provided between the medium-pressure circulation pipe 4 and the infrared heat collecting plate 60; the infrared heat collecting plate 60 is connected to the heat collecting end 61, and the other end of the heat collecting end 61 is connected to the low-pressure circulation pipe 5; the high-pressure circulation pipe 3 is connected to the first control valve 64, and the first control valve 64 is respectively connected to the heat exchanger 63 and the second control valve 65, the other end of the second control valve 65 is connected to the low-pressure circulation pipe 5, and the other end of the heat exchanger 63 is connected to the third control valve 66, and the third control valve 66 is connected to the medium-pressure circulation pipe 4.

[0035] In heating mode, at night, the second, third, and fourth control valves 65, 66, and 67 open first, while the first control valve 64 closes. This allows the heat stored in the energy tank 62 during the day to be extracted through cooling mode to heat the room. When the medium in the energy tank 62 reaches its phase transition temperature, the first control valve 64 opens, the second control valve 65 closes, and the third and fourth control valves 66, 67 remain open. This transfers heat from the high-temperature exhaust gas to the intake port through the medium in the energy tank 62, thus maintaining stable system operation. During the day, the first, second, and third control valves 64, 65, and 66 are closed, while the fourth control valve 67 opens first. Superheated return air passes through the energy tank 62, heating the low-temperature medium within. If the return air temperature exceeds the set value, the second and third control valves 65 and 66 open to cool the return air.

[0036] In the present invention, light energy and air energy are stored in the energy tank 62 in the form of phase change through phase change energy storage materials. When there is sufficient sunlight, solar energy can be used for heating, which is green and environmentally friendly. When there is insufficient sunlight, the collector can also collect part of the heat through thermal radiation. The air energy collector can also be used to collect heat, ensuring the heating needs.

[0037] The refrigerant can be selected from media such as Freon, ammonia, and carbon dioxide. This embodiment preferably uses carbon dioxide as the refrigerant medium for central air conditioning. Using carbon dioxide as a circulating working fluid has the advantages of large pressure difference, good fluidity, low density, and transcritical phase change, and the effect is more obvious when used in high-rise buildings. The refrigerant circulation pipeline is connected to a single-stage carbon dioxide circulation system that uses carbon dioxide as a single circulating working fluid. The meaning of single-stage is different from the cascade system. Only carbon dioxide is used for circulation without cascade. The multi-unit central air-conditioning system of this embodiment uses carbon dioxide as the working fluid. It can provide cooling or heating for higher floors in the vertical height. It can circulate a longer distance when used on flat floors and can drive more indoor units to work.

[0038] When carbon dioxide is used as the refrigerant, as shown in FIG2 , the condenser 11 is preferably a flash evaporator. The flash evaporator includes a closed housing 110, a negative pressure fan 111, and a heat exchange unit 112. The negative pressure fan 111 is located at the top of the closed housing 110 to create a negative pressure within the closed housing 110. Multiple heat exchange units 112 are stacked and arranged within the closed housing 110. The heat exchange units 112 include a water atomizer 113, multiple rows of coils for circulating the refrigerant, and fins for securing the multiple rows of coils. The multiple rows of coils and fins are secured by a mounting bracket. Carbon dioxide flows in through the inlet and out through the outlet. The multiple rows of coils in the multiple heat exchange units 112 are connected in series. The water atomizer 113 is connected to a water source to atomize water. The atomized water permeates the inner cavity of the closed housing 110. Under the action of the negative pressure, the liquid particles complete radiative heat exchange with the carbon dioxide in the multiple rows of coils before being drawn out of the closed housing 110 by the negative pressure fan 111. During cooling, the water microclusters within the cavity absorb the radiant heat from the carbon dioxide circulating within the multiple rows of coils, gradually decomposing from large microclusters into small microclusters that remove the heat and condense the carbon dioxide refrigerant into liquid. The water microclusters dynamically and continuously decompose into smaller water microclusters, removing the heat. Ultrasonic atomized water inherently has a descaling function, preventing scaling on the surfaces of the heat exchange tubes and fins. The water vapor after heat exchange is not circulated or recovered, but is directly discharged into the atmosphere. Because the decomposition of the water microclusters primarily converts heat into internal energy, the discharged water vapor is not hot, preventing the heat island effect. Stacking multiple heat exchange units 112 facilitates installation and maintenance. If a heat exchange unit 112 fails, the damaged unit can be removed for repair or replacement. Compared to existing air-cooled heat exchangers, this flash evaporator performs heat exchange within a closed housing 110, with virtually no air entering. When the outside temperature and humidity are high, the heat exchange effect is not affected by the temperature and humidity of the natural wind.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A multi-unit central air conditioning system for simultaneous cooling and heating, comprising a condensing module, a plurality of indoor fan coil units, a high-pressure flow pipe, a medium-pressure flow pipe, a low-pressure flow pipe, and an evaporation module, characterized in that: The condensing module includes a compressor, a condenser and a liquid storage tank connected in sequence, the high-pressure circulation pipe is connected to the exhaust end of the compressor; the medium-pressure circulation pipe is connected to the liquid storage tank and the evaporation module; the low-pressure circulation pipe is connected to the suction end of the compressor and the evaporation module; the indoor fan coil is connected to the high-pressure circulation pipe through a first branch pipe, connected to the low-pressure circulation pipe through a second branch pipe, and connected to the medium-pressure circulation pipe through a third branch pipe, a first solenoid valve is provided on the first branch pipe, and a second solenoid valve is provided on the second branch pipe.

2. A multi-split central air-conditioning system for simultaneous cooling and heating according to claim 1, characterized in that: The third branch pipe is provided with an electronic expansion valve.

3. The multi-split central air-conditioning system for simultaneous cooling and heating according to claim 1, characterized in that: When a portion of the indoor fan coil units need cooling, the first solenoid valve of the cooling indoor fan coil units is closed, and the refrigerant in the liquid storage tank passes through the medium-pressure flow pipe, the electronic expansion valve, the indoor fan coil units, the second solenoid valve, and the low-pressure flow pipe in sequence to complete the refrigeration cycle; When another part of the indoor fan coil needs to heat, the second solenoid valve of the heating indoor fan coil is closed, and the high-temperature refrigerant at the exhaust end of the compressor passes through the high-pressure circulation pipe, the first solenoid valve, the indoor fan coil, the electronic expansion valve, the evaporation module, and the low-pressure circulation pipe in sequence to complete the heating cycle.

4. The multi-split central air-conditioning system for simultaneous cooling and heating according to claim 1, characterized in that: A temperature sensor and a pressure sensor are provided at the exhaust end of the compressor; a temperature sensor is provided at the intake end of the compressor; a temperature sensor is provided on the pipe between the condenser and the liquid storage tank; a solenoid valve and a capillary tube are also provided on the pipe between the liquid storage tank and the compressor; temperature sensors are provided at the inlet and outlet ends of the indoor fan coil; and pressure sensors are respectively provided on the medium-pressure circulation pipe and the low-pressure circulation pipe.

5. The multi-split central air-conditioning system for simultaneous cooling and heating according to claim 4, characterized in that: A first constant pressure valve is provided on the pipeline connecting the compressor exhaust end of the condensing module and the condenser, and a second constant pressure valve is provided on the pipeline between the condenser and the liquid storage tank.

6. The multi-split central air-conditioning system for simultaneous cooling and heating according to claim 1, characterized in that: The central air conditioning system also includes floor heating pipes and / or domestic hot water pipes; The floor heating pipes are connected to the high-pressure circulation pipe and the medium-pressure circulation pipe respectively. An electronic expansion valve is provided on the connecting pipe between the floor heating pipe and the medium-pressure circulation pipe, and a manual stop valve is provided on the connecting pipe between the floor heating pipe and the high-pressure circulation pipe; The domestic hot water pipe is connected to the high-pressure circulation pipe and the medium-pressure circulation pipe respectively. An electronic expansion valve is provided on the connecting pipe between the domestic hot water pipe and the medium-pressure circulation pipe, and a manual stop valve is provided on the connecting pipe between the domestic hot water pipe and the high-pressure circulation pipe.

7. The multi-split central air-conditioning system for simultaneous cooling and heating according to claim 1, characterized in that: The evaporation module is a freeze-thaw cycle evaporator, which includes an infrared collector, a heat collecting end, an energy tank and a heat exchanger. The energy tank stores freeze-thaw medium, the heat collecting end and the heat exchanger are arranged in the energy tank, and the two ends of the heat exchanger are respectively connected to the refrigerant circulation pipeline.

8. The multi-split central air-conditioning system for simultaneous cooling and heating according to claim 7, characterized in that: The medium-pressure circulation pipe is connected to the infrared heat collecting plate, and a fourth control valve is arranged between the medium-pressure circulation pipe and the infrared heat collecting plate; the infrared heat collecting plate is connected to the heat collecting end, and the other end of the heat collecting end is connected to the low-pressure circulation pipe; the high-pressure circulation pipe is connected to the first control valve, and the first control valve is respectively connected to the heat exchanger and the second control valve, the other end of the second control valve is connected to the low-pressure circulation pipe, the other end of the heat exchanger is connected to the third control valve, and the third control valve is connected to the medium-pressure circulation pipe.

9. The multi-split central air-conditioning system for simultaneous cooling and heating according to claim 1, characterized in that: The refrigerant choice is Freon, ammonia or carbon dioxide.

10. The multi-split central air-conditioning system for simultaneous cooling and heating according to claim 1, characterized in that: Carbon dioxide is selected as a single-cycle refrigerant. The condenser is a flash evaporator, which includes a closed shell, a negative pressure fan, and a heat exchange unit. The negative pressure fan is arranged on the top of the closed shell to form a negative pressure in the closed shell. Multiple heat exchange units are stacked and arranged in the closed shell. The heat exchange unit includes a water atomizer, multiple rows of coils for circulating the refrigerant, and fins for fixing the multiple rows of coils. The multiple rows of coils and fins are fixed by a fixing frame. Carbon dioxide flows in from the inlet end and is discharged from the outlet end. The water atomizer is connected to a water source and is used to atomize water.

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