Single-stage subcritical carbon dioxide multi-split refrigeration and heating system

Abstract

A single-stage subcritical carbon dioxide multi-split refrigeration and heating system, comprising a compressor (2), a bidirectional evaporative heat exchanger (1), a liquid storage device (6), a four-way reversing valve (5), a liquid circulation pipe (3), and a gas circulation pipe (4). Four interfaces of the four-way reversing valve (5) are respectively connected to a gas suction end of the compressor (2), an exhaust end of the compressor (2), the bidirectional evaporative heat exchanger (1), and the gas circulation pipe (4); the bidirectional evaporative heat exchanger (1) is connected to the liquid storage device (6); the liquid storage device (6) is connected to the liquid circulation pipe (3); and a tail end assembly is connected to the liquid circulation pipe (3) and the gas circulation pipe (4), separately. The beneficial effects of the present application are: a plurality of working modes of switching between refrigeration and heating, partial tail end refrigeration, and partial tail end heating can be achieved in one system, the diversity of the overall operation condition of the multi-split refrigeration and heating system is improved without additionally providing a complex refrigerant switching pipeline, and various refrigeration and heating requirements of one building complex are met by means of one system. The efficiency of the system is further improved, the power consumption is reduced, and energy conservation and environmental protection are achieved.

Description

FIELD

[0001] The present application relates to the technical field of air conditioning, and in particular to a single-stage subcritical carbon dioxide multi-split refrigeration and heating system.BACKGROUND

[0002] Construction industry is emerging as a major force for the reduction of carbon emissions for tackling climate change. Statistics show that a construction energy consumption accounts for approximately one-third of the total society energy consumption, and thus reducing the construction energy consumption can significantly improve the total society energy consumption situation and have a very obvious effect on energy conservation, emission reduction, and environmental protection by reducing the construction energy consumption. An air conditioning energy consumption accounts for a considerable proportion of the construction energy consumption. In the conventional multi-split central air conditioning system, a cascade refrigeration system of Freon refrigeration system and water circulation system is typically used, in which the water circulation system is used to adjust temperature. As Freon has the disadvantages of high density, high viscosity, and low pressure difference, efforts are being made to develop methods and technologies to solve the pollution problem caused by using Freon. The main approaches to solving the environmental pollution problem include restriction and prohibition, development of alternatives, and harmlessness treatment of Freon. As the international community is increasingly focusing on energy conservation, emission reduction, and environmental protection, Freon refrigerant is gradually phased out. A carbon dioxide, as a safe and environmentally friendly refrigerant, has a broad application prospect and considerable economic value. Due to the inherent characteristic of a high critical pressure of carbon dioxide refrigerant, the promotion and application of carbon dioxide refrigeration system are restricted.

[0003] In summary, it is required to provide an energy-saving, environment friendly, and high efficient single-stage subcritical carbon dioxide multi-split refrigeration and heating system that utilizes carbon dioxide as the cycle working medium.SUMMARY

[0004] The present application is aimed to overcome the defects of the existing technology and provides a single-stage subcritical carbon dioxide multi-split refrigeration and heating system that utilizes carbon dioxide as the cycle working medium and is energy-saving, environmentally friendly, and highly efficient.

[0005] The technical solution of the single-stage subcritical carbon dioxide multi-split refrigeration and heating system provided in the present application is as follows.

[0006] A single-stage subcritical carbon dioxide multi-split refrigeration and heating system, includes: a compressor, a bidirectional evaporation heat exchanger, a liquid reservoir, a four-way valve, a liquid circulation pipe, and a gas circulation pipe. The four-way valve has four ports, which are respectively connected to a suction end of the compressor, a discharge end of the compressor, the bidirectional evaporation heat exchanger, and the gas circulation pipe, the bidirectional evaporation heat exchanger is connected to the liquid reservoir, the liquid reservoir is connected to the liquid circulation pipe, and a terminal assembly is connected to the liquid circulation pipe and the gas circulation pipe, respectively. In a refrigeration mode, the four-way valve communicates the discharge end of the compressor with the bidirectional evaporation heat exchanger and communicates the suction end of the carbon dioxide compressor with the gas circulation pipe and in a heating mode, the four-way valve communicates the discharge end of the compressor with the gas circulation pipe and communicates the suction end of the carbon dioxide compressor with the bidirectional evaporation heat exchanger.

[0007] In an embodiment, the compressor, the bidirectional evaporation heat exchanger, the liquid reservoir, and a terminal end of the refrigeration and heating system form a single-stage carbon dioxide cycle system, which can operate in a temperature below a critical point of a condensation temperature.

[0008] In an embodiment, a regulating valve is provided on a pipeline between the bidirectional evaporation heat exchanger and the liquid reservoir.

[0009] In an embodiment, a domestic hot water tank is provided on a pipeline between the compressor and the four-way valve, an inlet end and an outlet end of the domestic hot water tank are each provided with a regulating valve, and the outlet end of the domestic hot water tank is provided with a thermometer.

[0010] In an embodiment, the bidirectional evaporation heat exchanger includes a closed housing, a centrifugal fan, a heat exchange pipe set, and an atomizing nozzle. The centrifugal fan is provided on one side of the closed housing, and the atomizing nozzle and the heat exchange pipe set are provided inside the closed housing. The centrifugal fan is used for discharging water vapor or air inside the closed housing, and the water vapor or the air inside the closed housing is used for exchanging heat with a refrigerant flowing through the heat exchange pipe set. An electric roller shutter is provided on the other side of the closed housing, and the electric roller shutter is open or closed so as to switch the heat exchanger into the heating mode or the refrigeration mode.

[0011] In an embodiment, the atomizing nozzle is connected to a high-pressure water pipe, the centrifugal fan is a backward-inclined centrifugal fan, and a grid plate is provided on one side of the electric roller shutter.

[0012] In an embodiment, the terminal assembly includes a fan coil unit, an inlet end and an outlet end of the fan coil unit are respectively connected to the liquid circulation pipe and the gas circulation pipe, an inlet pipeline and an outlet pipeline of the fan coil unit are each provided with a thermometer, and one of the inlet pipeline and the outlet pipeline is provided with a regulating valve.

[0013] In an embodiment, the terminal assembly includes floor heating, an inlet end and an outlet end of the floor heating are respectively connected to the liquid circulation pipe and the gas circulation pipe, an inlet pipeline and an outlet pipeline of the floor heating are each provided with a regulating valve, and the outlet end of the floor heating is provided with a check valve and a thermometer.

[0014] In an embodiment, the floor heating is configured as multi-row pipes arranged in rooms in parallel, the pipes of the floor heating include a gas-supply pipe, a liquid-return pipe, and multiple branch pipes. Each branch pipe is configured to be continuously bent outward and coiled in a floor, the floor includes a concrete slab, a reflective layer, a steel mesh, a thermal storage layer, and a tile layer which are laid in sequence, and the multiple branch pipes are fixed to the steel mesh by clamps and abut against the coiled branch pipes.

[0015] In an embodiment, the terminal assembly includes a cold and heat storage device, an inlet end and an outlet end of the cold and heat storage device are respectively connected to the liquid circulation pipe and the gas circulation pipe, and an inlet pipeline and an outlet pipeline of the cold and heat storage device are each provided with a thermometer and a regulating valve.

[0016] The implementation of the present application includes the following technical effects.

[0017] In the single-stage subcritical carbon dioxide multi-split refrigeration and heating system of the present application, by providing the liquid circulation pipe, the gas circulation pipe, and the four-way valve as well as improving the connection methods among the bidirectional evaporation heat exchanger, the compressor, the liquid circulation pipe, the gas circulation pipe, and the four-way valve, a terminal heating assembly or a terminal refrigeration assembly is connected to the liquid circulation pipe and the gas circulation pipe, which can achieve multiple working modes in one system, including a switching between refrigeration and heating, and a part of terminal ends for refrigeration and a part of terminal ends for heating. Therefore, it improves the operation diversity of the whole multi-split refrigeration and heating system without adding complex refrigerant switching pipelines, meets various comfort needs of different people and refrigeration and heating needs at different terminals, that is, meeting various refrigeration and heating needs in one construction complex by one system. It further enhances system efficiency, significantly reduces power consumption, and achieves energy conservation and environmental protection. Moreover, the components, such as cold and heat storage device (e.g., cold and heat storage swimming pool) may be provided to ensure efficient and safe operation of the system.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a schematic view of a single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to an embodiment of the present application in a refrigeration state. FIG. 2 is a schematic view of the single-stage subcritical carbon dioxide multi- split refrigeration and heating system according to an embodiment of the present application in a heating state. FIG. 3 is a schematic structural view of a bidirectional evaporation heat exchanger.

[0019] Numeral references are listed below: 1. bidirectional evaporation heat exchanger; 100. closed housing; 101. centrifugal fan; 102. heat exchange pipe set; 103. atomizing nozzle; 104. electric roller shutter; 105. grid plate; 2. compressor; 3. liquid circulation pipe; 4. gas circulation pipe; 5. four-way valve; 6. liquid reservoir; 7. regulating valve; 8. thermometer; 9. check valve; 10. domestic hot water tank; 11. fan coil unit; 12. floor heating; 13. cold and heat storage device.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The present application will be described in detail below with reference to embodiments and accompanying drawings. It should be noted that the described embodiments are merely intended to facilitate the understanding of the present application and do not intend to limit it in any manner.

[0021] As shown in FIGS. 1 and 2, a single-stage subcritical carbon dioxide multi- split refrigeration and heating system is provided in this embodiment, which includes a compressor 2, a bidirectional evaporation heat exchanger 1, a liquid reservoir 6, a four-way valve 5, a liquid circulation pipe 3, and a gas circulation pipe 4. The four-way valve 5 has four ports, which are respectively connected to a suction end of the compressor 2, a discharge end of the compressor 2, the bidirectional evaporation heat exchanger 1, and the gas circulation pipe 4. The bidirectional evaporation heat exchanger 1 is connected to the liquid reservoir 6, and the liquid reservoir 6 is connected to the liquid circulation pipe 3. A terminal assembly is connected to the liquid circulation pipe 3 and the gas circulation pipe 4, respectively. As shown in FIG. 1, in a refrigeration mode, the four-way valve 5 communicates the discharge end of the compressor 2 with the bidirectional evaporation heat exchanger 1 and communicates the suction end of the carbon dioxide compressor 2 with the gas circulation pipe 4. As shown in FIG. 2, in a heating mode, the four-way valve 5 communicates the discharge end of the compressor 2 with the gas circulation pipe 4 and communicates the suction end of the carbon dioxide compressor 2 with the bidirectional evaporation heat exchanger 1. The compressor 2, the bidirectional evaporation heat exchanger 1, the liquid reservoir 6, and a terminal end of the refrigeration and heating system form a single-stage carbon dioxide cycle system, which can operate in a temperature below the critical point of a condensation temperature (subcritical). In this embodiment, the carbon dioxide medium is used as the refrigerant medium for the refrigeration and heating system. The carbon dioxide is used as the cycle working medium, which has advantages of large pressure difference, good fluidity, low density, and transcritical phase change, and thus is more effective for high-rise buildings. The meaning of "single-stage" differs from a cascade system in that: only the carbon dioxide medium is used for circulation without cascading. The refrigeration and heating system in this embodiment uses carbon dioxide as the working medium, which can supply cooling or heating to higher floors in a vertical direction, and can perform circulating over longer distances in case of horizontal-floor application so as to operate more indoor units.

[0022] In the single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to the present application, by providing the liquid circulation pipe 3, the gas circulation pipe 4, and the four-way valve 5 as well as improving the connection methods among the bidirectional evaporation heat exchanger 1, the compressor 2, the liquid circulation pipe 3, the gas circulation pipe 4, and the four-way valve 5, a terminal heating assembly or a terminal refrigeration assembly is connected to the liquid circulation pipe 3 and the gas circulation pipe 4, which can achieve multiple working modes in one system, including a switching between refrigeration and heating, and a part of terminal ends for refrigeration and a part of terminal ends for heating. Therefore, it improves the operation diversity of the whole multi-split refrigeration and heating system without adding complex refrigerant switching pipelines, meets various comfort needs of different people and refrigeration and heating needs at different terminals, that is, meeting various refrigeration and heating needs in one construction complex by one system. It further enhances system efficiency, significantly reduces power consumption, and achieves energy conservation and environmental protection. Moreover, the components, such as cold and heat storage device 13 (e.g., cold and heat storage swimming pool) may be provided to ensure efficient and safe operation of the system.

[0023] As shown in FIG. 1, a regulating valve 7 is provided on a pipeline between the bidirectional evaporation heat exchanger 1 and the liquid reservoir 6. A domestic hot water tank 10 is provided on the pipeline between the compressor 2 and the four-way valve 5. An inlet end and an outlet end of the domestic hot water tank 10 are each provided with a regulating valve 7, and the outlet end of the domestic hot water tank 10 is provided with a thermometer 8. When a refrigeration mode of the central air conditioning system is required, a hot water supply device can cool down the hot carbon dioxide gas, which increases the heat exchange efficiency of the heat exchanger, and thus can not only provide domestic hot water but also reduce the cooling pressure of the refrigeration system, making it very energy-efficient. With such configuration, it ensures an adequate supply of domestic hot water.

[0024] A bidirectional evaporation heat exchanger refers to a device capable of switching between a refrigeration mode and a heating mode, or a device in combination of a separate refrigeration component and a separate heating component. As shown in FIG. 3, preferably, the bidirectional evaporation heat exchanger 1 includes a closed housing 100, a centrifugal fan 101, a heat exchange pipe set 102, and an atomizing nozzle 103. The centrifugal fan 101 is provided on one side of the closed housing 100, and the atomizing nozzle 103 and the heat exchange pipe set 102 are provided inside the closed housing 100. The centrifugal fan 101 is used to discharge water vapor or air inside the closed housing 100, and the water vapor or air inside the closed housing 100 exchanges heat with the refrigerant flowing through the heat exchange pipe set 102. An electric roller shutter 104 is provided on the other side of the closed housing 100, and the electric roller shutter 104 is open or closed so as to switch the heat exchanger into the heating mode or the refrigeration mode. By providing the electric roller shutter 104 in cooperation with the flow direction of the refrigerant, the switching between the refrigeration mode and the heating mode can be achieved by one single device, which reduces equipment costs and system complexity. The atomizing nozzle 103 is connected to a high-pressure water pipe and is used to generate atomized water. The centrifugal fan 101 is a backward-inclined centrifugal fan 101. A grid plate 105 is provided on one side of the electric roller shutter. During refrigeration (for example, in summer), the electric roller shutter 104 is closed to prevent air from flowing in, and the operation of high-pressure water atomization is performed. The bidirectional evaporation heat exchanger 1 functions as a flash condenser. When the electric roller shutter 104 is closed, the centrifugal fan 101 continuously discharges the water vapor inside the closed housing 100, forming a negative pressure environment in an accommodating chamber. The atomized water formed by the atomizing nozzle 103 exchanges heat with the high-temperature refrigerant in the heat exchange pipe set 102 in the negative pressure environment of the accommodating chamber, and the water vapor rapidly flashes, changing phase from water mist to steam, absorbing heat, reducing the ambient temperature inside the closed housing 100, and liquefying and condensing the refrigerant. During heating (for example, in winter), the electric roller shutter 104 is retracted to allow air flowing in, the operation of high-pressure water atomization is stopped, and the bidirectional evaporation heat exchanger 1 functions as an evaporator. When the electric roller shutter 104 is retracted, the external air exchanges heat with the low-temperature refrigerant inside the heat exchange pipe set 102, causing the refrigerant to vaporize and evaporate. In the refrigeration mode of the bidirectional evaporation heat exchanger 1, the water vapor after heat exchanging is not circulated or recycled but is directly discharged into the atmosphere. During the decomposition process of water droplets, most of the heat is converted into internal energy, so the temperature of the discharged water vapor is not high and does not cause a heat island effect. Heat exchange occurs inside the closed housing 100 during refrigeration, with almost no air flowing in. When the external temperature and humidity are both high, the heat exchange effect is not affected by the external temperature and humidity.

[0025] As shown in FIGS. 1 and 2, the terminal assembly includes a fan coil unit 11. The inlet and outlet ends of the fan coil unit 11 are respectively connected to the liquid circulation pipe 3 and the gas circulation pipe 4. The inlet and outlet pipeline of the fan coil unit 11 are each provided with the thermometer 8, and one of the inlet and outlet pipelines is provided with a regulating valve 7. The thermometer 8 is used to provide temperature feedback and adjust the refrigeration or heating capacity. The flow directions of the refrigerant in the refrigeration and heating modes are opposite to each other, as indicated by the arrows in FIGS. 1 and 2. The terminal assembly includes a floor heating 12, and inlet and outlet ends of the floor heating 12 are respectively connected to the liquid circulation pipe 3 and the gas circulation pipe 4. The inlet and outlet pipelines of the floor heating 12 are each provided with a regulating valve 7, and the outlet end of the floor heating 12 is provided with a check valve 9 and a thermometer 8. The check valve 9 can prevent the back flow of liquid refrigerant, and the thermometer 8 is used to provide temperature feedback and adjust the heating capacity. When the system is in the refrigeration state, the regulating valve 7 is closed, and the floor heating 12 does not operate. The floor heating 12 is configured as multi-row pipes arranged in multiple rooms in parallel. The pipes of the floor heating 12 include a gas-supply pipe, a liquid-return pipe, and multiple branch pipes. The branch pipes are continuously bent outward and are coiled in a floor. The floor consists of a concrete slab, a reflective layer, a steel mesh, a thermal storage layer, and a tile layer, which are laid in sequence. The branch pipes are fixed to the steel mesh by clamps and abut against a coiled-pipe layer. Specifically, the reflective layer is made of aluminum foil or extruded insulation boards having aluminum foil. The aluminum foil reflects and transfers the heat radiated by the branch pipes to an upper end of the reflective layer, achieving uniform heat conduction. The thermal storage layer is formed by a mixture of cobblestone, sand, and cement. The cobblestone has good thermal conductivity and is smooth and edgeless, which is beneficial for heat transfer and protecting the branch pipes. The carbon dioxide, which has excellent thermal conductivity, is used as the medium for transferring heat to the floor. During the heat transferring process, carbon dioxide enters the branch pipes from the gas-supply pipe in a gaseous state, exchanges heat with the floor in the branch pipes, cools down, and then changes into a liquid state and flows out through the liquid-return pipe. Compared to the conventional floor heating 12 that uses water as the medium, carbon dioxide directly heats the floor, which eliminates the intermediate transfer step in which Freon transfers heat to water and then water transfers heat to the floor, and thus it is beneficial for improving heat transfer efficiency and reducing heat transfer loss, thereby providing a more suitable indoor temperature, distributing indoor heat more evenly, improving heat utilization efficiency, and reducing the use cost of floor heating 12.

[0026] As shown in FIG. 1, the terminal assembly includes a cold and heat storage device 13. The inlet and outlet ends of the cold and heat storage device 13 are respectively connected to the liquid circulation pipe 3 and the gas circulation pipe 4. The inlet and outlet pipelines of the cold and heat storage device 13 are each provided with a thermometer 8 and a regulating valve 7. The cold and heat storage device 13 may be a swimming pool. The system can not only heat the pool water to a temperature suitable for swimming, but also has the function of cold and heat storage. When a large refrigeration capacity in the room is required and the system cannot meet, the pool functions as a condenser to discharge the heat from the room. When a large heating capacity in the room is required and the system cannot meet, the pool functions as an evaporator to extract heat from the pool and supply it to the room. The refrigeration and heating system can also serve multiple purposes, such as producing domestic hot water. Further, the cold and heat storage device 13 plays an important balancing role in the refrigeration and heating system. The cold and heat storage device 13 may be a swimming pool, which takes the advantage of high latent heat of water to store cold and heat and thus is economical and convenient. The swimming pool can be set in a desired temperature range. When the refrigeration and heating system has excess heating capacity, the heat from the refrigeration and heating system is supplemented to the swimming pool to heat it up. When the refrigeration and heating system has excess cooling capacity, the cool from the system is supplemented to the swimming pool to cool it down. According to the needs of the refrigeration and heating system, cool and heat can be extracted and utilized from the swimming pool, which ensures efficient operation of the refrigeration and heating system without wasting excess cool and heat, allowing for on-demand extraction of cool and heat. It can fully utilize nighttime off-peak electricity, reducing the impact on the local power grid.

[0027] In this embodiment, the regulating valve may be solenoid valve or electronic expansion valve.

[0028] In the illustration of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "installing", "joining", "communicating", "connecting", and "linking" should be broadly understood. For example, they may refer to fixed connections, detachable connections, or integral connections, they may refer to mechanical connections or electrical connections, they may refer to direct connections or indirect connections through intermediaries, and they may refer to communications between two components. For those skilled in the art, the specific meanings of the aforementioned terms in the present application can be understood based on specific circumstances.

[0029] Finally, it should be noted that the above embodiments are merely used to illustrate the technical solutions of the present application, and are not intended to limit the protection scope of the present application. Although the present application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present application without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A single-stage subcritical carbon dioxide multi-split refrigeration and heating system, comprising: a compressor; a bidirectional evaporation heat exchanger; a liquid reservoir; a four-way valve; a liquid circulation pipe; and a gas circulation pipe, wherein the four-way valve has four ports, which are respectively connected to a suction end of the compressor, a discharge end of the compressor, the bidirectional evaporation heat exchanger, and the gas circulation pipe, and, the bidirectional evaporation heat exchanger is connected to the liquid reservoir, the liquid reservoir is connected to the liquid circulation pipe, and a terminal assembly is connected to the liquid circulation pipe and the gas circulation pipe, respectively; in a refrigeration mode, the four-way valve communicates the discharge end of the compressor with the bidirectional evaporation heat exchanger and communicates the suction end of the carbon dioxide compressor with the gas circulation pipe; and in a heating mode, the four-way valve communicates the discharge end of the compressor with the gas circulation pipe and communicates the suction end of the carbon dioxide compressor with the bidirectional evaporation heat exchanger.

2. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 1, wherein the compressor, the bidirectional evaporation heat exchanger, the liquid reservoir, and a terminal assembly of the single-stage subcritical carbon dioxide multi-split refrigeration and heating system form a single-stage carbon dioxide cycle system, which is operable in a temperature below a critical point of a condensation temperature.

3. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 1, wherein a regulating valve is provided on a pipeline between the bidirectional evaporation heat exchanger and the liquid reservoir.

4. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 1, wherein a domestic hot water tank is provided on a pipeline between the compressor and the four-way valve, an inlet end and an outlet end of the domestic hot water tank are each provided with a regulating valve, and the outlet end of the domestic hot water tank is provided with a thermometer.

5. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 1, wherein the bidirectional evaporation heat exchanger comprises a closed housing, a centrifugal fan, a heat exchange pipe set, and an atomizing nozzle, wherein the centrifugal fan is provided on one side of the closed housing, and the atomizing nozzle and the heat exchange pipe set are provided inside the closed housing; the centrifugal fan is configured for discharging water vapor or air inside the closed housing, and the water vapor or the air inside the closed housing is configured for exchanging heat with a refrigerant flowing through the heat exchange pipe set; and an electric roller shutter is provided on the other side of the closed housing, and the electric roller shutter is open or closed so as to switch the heat exchanger into the heating mode or the refrigeration mode.

6. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 5, wherein the atomizing nozzle is connected to a high-pressure water pipe, the centrifugal fan is a backward-inclined centrifugal fan, and a grid plate is provided on one side of the electric roller shutter.

7. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 1, wherein the terminal assembly comprises a fan coil unit, an inlet end and an outlet end of the fan coil unit are respectively connected to the liquid circulation pipe and the gas circulation pipe, an inlet pipeline and an outlet pipeline of the fan coil unit are each provided with a thermometer, and one of the inlet pipeline and the outlet pipeline is provided with a regulating valve.

8. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 1, wherein the terminal assembly comprises a floor heating, an inlet end and an outlet end of the floor heating are respectively connected to the liquid circulation pipe and the gas circulation pipe, an inlet pipeline and an outlet pipeline of the floor heating are each provided with a regulating valve, and the outlet end of the floor heating is provided with a check valve and a thermometer.

9. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 8, wherein the floor heating is configured as multi-row pipes arranged in rooms in parallel, the pipes of the floor heating comprise a gas-supply pipe, a liquid-return pipe, and a plurality of branch pipes, wherein each branch pipe is configured to be continuously bent outward and coiled in a floor, the floor comprises a concrete slab, a reflective layer, a steel mesh, a thermal storage layer, and a tile layer which are laid in sequence, and the plurality of branch pipes are fixed to the steel mesh by clamps and abut against a coiled -pipes layer.

10. The single-stage subcritical carbon dioxide multi-split refrigeration and heating system according to claim 1, wherein the terminal assembly comprises a cold and heat storage device, an inlet end and an outlet end of the cold and heat storage device are respectively connected to the liquid circulation pipe and the gas circulation pipe, and an inlet pipeline and an outlet pipeline of the cold and heat storage device are each provided with a thermometer and a regulating valve.

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