Single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system and control method

Abstract

A single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system and a control method. The system comprises a bidirectional evaporative heat exchanger (1), a compressor (2), a high-pressure gas refrigerant circulation pipe (3), a medium-pressure liquid refrigerant circulation pipe (4), and a low-pressure gas refrigerant circulation pipe (5); control valve members (8) are opened and closed to control the communication state of the bidirectional evaporative heat exchanger (1), and the high-pressure gas refrigerant circulation pipe (3) and the low-pressure gas refrigerant circulation pipe (5); a tail end heating assembly is communicated with the high-pressure gas refrigerant circulation pipe (3) and the medium-pressure liquid refrigerant circulation pipe (4); and the tail end is communicated with the medium-pressure liquid refrigerant circulation pipe (4) and the low-pressure gas refrigerant circulation pipe (5), separately. The beneficial effects of the present application are: the functions of refrigeration, heating, partial tail end refrigeration, and partial tail end heating, and free switching the same tail end between the refrigeration mode and the heating mode are achieved in one system, the bidirectional evaporative heat exchanger (1) is switched to a refrigeration mode or a heating mode according to the refrigeration and heating requirements of the whole system, and the refrigeration and heating requirements of the whole system are balanced. The power consumption is greatly reduced, and energy conservation and environmental protection are really 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 hybrid refrigeration and heating equalization system and a control method.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. It has become a trend of applying solutions, including widespread promotion of energy-efficient buildings, raising energy efficiency standards, implementing renovation projects, strengthening supervision, and promoting renewable energy, to continuously improving building energy efficiency. An air conditioning energy consumption accounts for a considerable proportion of the construction energy consumption. The air conditioner is frequently used during the winter and summer. In the context of energy scarcity, high energy consumption, and prominent environmental pollution problems, energy conservation and emission reduction are essential for sustainable social development. The conventional multi-split air conditioning system mainly includes a compressor for heating and a condenser for cooling. The heat exchange principle is as follows: the compressor is used to compress the refrigerant (ammonia or Freon) into a high-pressure saturated gas, which is then condensed by the condenser. Because it is hard for the condensed ammonia or Freon to flow through pipes rapidly, the condensed ammonia or Freon needs to be throttled by a throttling device first and then enter the evaporator to be cooled to a set temperature, and is transported to the energy-consuming components for heat exchange. That is, during heat exchange, the refrigerant needs to be compressed to a temperature higher than the set temperature before cooling, which significantly increases the energy consumption of the compressor and condenser, thereby resulting in low heat exchange efficiency. Furthermore, the emission of Freon aggravates the greenhouse effect, and the ammonia is highly explosive, which is inconsistent with the national concept of environmental protection, energy conservation, and safety.

[0003] With the improvement of living standards, the demands for cooling and heating in the same building are also various. The multi-split air conditioning system cools or heats indoor spaces using a refrigeration cycle to provide unified cooling in the summer and unified heating in the winter, which is the basic function of air conditioning. The problem that arises is: once the refrigeration mode is activated, all air conditioners must operate in refrigeration mode. Similarly, if the heating mode is activated, all air conditioners must operate in heating mode. During transitional seasons, such as the fluctuating weather in southern China, different people have different temperature comfort demands. For example, healthy middle-aged and young people might feel a little warm and need the air conditioner for cooling, while the elderly and children might feel cold and need heating. Currently, most conventional multi-split air conditioning units on the market can only operate in a single cooling or heating mode. To achieve simultaneous cooling and heating in different rooms by the same system, it needs to install two separate air conditioning systems, increasing construction costs.

[0004] Therefore, it is required to provide a single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system that can operate in a refrigeration mode and a heating mode simultaneously by one single system, allows for convenient switching between the refrigeration mode and the heating mode, ensures equalized utilization of cold and heat, and is energy-efficient and environmentally friendly.SUMMARY

[0005] The present application is aimed to overcome the deficiencies of the existing technology and provides a single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system that can operate in a refrigeration mode and a heating mode simultaneously by one single system, allows for a convenient switching between the refrigeration mode and the heating mode, ensures equalized utilization of cold and heat, and is energy-efficient and environmentally friendly. A control method is further provided.

[0006] The technical solution of the single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system provided in the present application is as follows:

[0007] A single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system includes: a bidirectional evaporation heat exchanger, a compressor, a high-pressure gas refrigerant circulation pipe, a medium-pressure liquid refrigerant circulation pipe, and a low-pressure gas refrigerant circulation pipe. A suction end of the compressor is in communication with the low-pressure gas refrigerant circulation pipe, and a discharge end of the compressor is in communication with the high-pressure gas refrigerant circulation pipe. The bidirectional evaporation heat exchanger has a first port and a second port, the first port is in communication with the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe through a control valve, communication states between the first port and the high-pressure gas refrigerant circulation pipe and between the first port and the low-pressure gas refrigerant circulation pipe are controlled by an on / off operation of the control valve. The second port is in communication with the medium-pressure liquid refrigerant circulation pipe. A terminal heating assembly is in communication with the high-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe, and a terminal refrigeration assembly is in communication with the medium-pressure liquid refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe.

[0008] In an embodiment, the compressor, the bidirectional evaporation heat exchanger, and terminals of the equalization system form a single-stage carbon dioxide circulation system, which can operate below a critical point of a condensation temperature.

[0009] In an embodiment, when switching between a refrigeration state and a heating state of the terminal assembly is required, communication states between the terminal assembly and the high-pressure gas refrigerant circulation pipe and between the terminal assembly and the low-pressure gas refrigerant circulation pipe is controlled by an on / off operation of the control valve, so as to achieve the switching between a refrigeration mode and a heating mode.

[0010] In an embodiment, a liquid receiver is provided between the second port of the bidirectional evaporation heat exchanger and the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided between the liquid receiver and the second port.

[0011] In an embodiment, the control valve is configured as a three-way valve or two regulating valves that are respectively located on different pipelines.

[0012] 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 located on one side of the closed housing, and the atomizing nozzle and the heat exchange pipe set are located inside the closed housing. The centrifugal fan is configured for discharging water vapor or air inside the closed housing, the water vapor or air inside the closed housing is configured 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 bidirectional evaporation heat exchanger into the heating state or the refrigeration state.

[0013] In an embodiment, a grid plate is provided on one side of the electric roller shutter.

[0014] In an embodiment, the terminals include a fan coil unit capable of switching between the refrigeration state and the heating state, one port of the fan coil unit is in communication with the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on a pipeline. The other port of the fan coil unit is respectively in communication with the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe through the control valve, and communication states between the other port and the high-pressure gas refrigerant circulation pipe and between the other port and the low-pressure gas refrigerant circulation pipe are controlled by an on / off operation of the control valve. The regulating valve and a thermometer are provided at the one port and the other port of the fan coil unit, respectively.

[0015] In an embodiment, the terminals include a floor heating that can only operate in a heating mode, an inlet end of the floor heating is in communication with the high-pressure gas refrigerant flow pipe, and an outlet end of the floor heating is in communication with the medium-pressure liquid refrigerant flow pipe. The inlet end of the floor heating is provided with a regulating valve, and the outlet end of the floor heating is provided with a check valve, a regulating valve, and a thermometer.

[0016] In an embodiment, the floor heating is configured as multi-row pipelines installed in rooms in parallel, pipes of the floor heating include a gas-supply pipe, a liquid-return pipe, and multiple branch pipes. The multiple branch pipes are continuously bent outward and are 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. The multiple branch pipes are fixed to the steel mesh by a clamp and abut against a coiled-pipe layer. The reflective layer is made of aluminum foil or extruded insulation boards having aluminum foil, and the thermal storage layer is formed by a mixture of cobblestone, sand, and cement.

[0017] In an embodiment, the terminals include a domestic hot water tank that only operates in a heating mode, an inlet end of the domestic hot water tank is in communication with the high-pressure gas refrigerant circulation pipe, and an outlet end of the domestic hot water tank is in communication with the medium-pressure liquid refrigerant circulation pipe. The inlet end of the domestic hot water tank is provided with a regulating valve, and the outlet end of the domestic hot water tank is provided with a regulating valve and a thermometer.

[0018] In an embodiment, the terminals include a cold and heat accumulator that can switching between the refrigeration state and the heating state, one port of the cold and heat accumulator is in communication with the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on a pipeline. The other port of the cold and heat accumulator is connected to the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe through the control valve, respectively. Communication states between the other port of the cold and heat accumulator and the high-pressure gas refrigerant circulation pipe and between the other port of the cold and heat accumulator and the low-pressure gas refrigerant circulation pipe are controlled by an on / off operation of the control valve, and a thermometer is provided at the one port of the cold and heat accumulator.

[0019] In an embodiment, the terminals include an infrared radiation collector, an inlet end of the infrared radiation collector is in communication with the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on a pipeline. An outlet end of the infrared radiation collector is in communication with the low-pressure gas refrigerant circulation pipe.

[0020] In an embodiment, the terminals include a wine cabinet heat exchanger that only operates in a refrigeration mode, an inlet end of the wine cabinet heat exchanger is in communication with the medium-pressure liquid refrigerant circulation pipe and a regulating valve is provided on a pipeline. An outlet end of the wine cabinet heat exchanger is in communication with the low-pressure gas refrigerant circulation pipe.

[0021] In an embodiment, the regulating valve is a solenoid valve or an electronic expansion valve.

[0022] A control method of a single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system, including: setting a discharge pressure and a suction pressure of a compressor of the equalization system. A heating capacity of the equalization system is determined by the discharge pressure, a cooling capacity of the equalization system is determined by the suction pressure, and a control module is provided to monitor whether the discharge pressure and the suction pressure of the compressor are within a set range. If the discharge pressure or the suction pressure of the compressor is out of the set range, first determining whether a heat exchange terminal or a cold exchange terminal operates in a set operation state, if the heat exchange terminal or the cold exchange terminal does not operate in the set operation state, the number of heat exchange terminal or cold exchange terminal in operation is adjusted to ensure that the discharge pressure and the suction pressure of the compressor are both within the set range. If the heat exchange terminal or the cold exchange terminal operates in the set operation state, one or more of a bidirectional evaporation heat exchanger, a cold and heat accumulator, and an infrared radiation collector are controlled to operate in a heating state to ensure that the discharge pressure of the compressor is within the set range, or, the bidirectional evaporation heat exchanger or the cold and heat accumulator is controlled to be in a refrigeration state to ensure that the suction pressure of the compressor is within the set range.

[0023] In an embodiment, when the bidirectional evaporation heat exchanger operates in a refrigeration mode, two ends of the bidirectional evaporation heat exchanger are controlled to be respectively in communication with a high-pressure gas refrigerant flow pipe and a medium-pressure liquid refrigerant flow pipe through a control valve, an electric roller shutter is closed to prevent air from flowing in, an operation of high-pressure water atomization is performed, and the bidirectional evaporation heat exchanger operates as a flash condenser. When the bidirectional evaporation heat exchanger 1 operates in a heating mode, the two ends of the bidirectional evaporation heat exchanger are controlled to be respectively in communication with a low-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant flow pipe through the control valve, the electric roller shutter is retracted to allow air flowing in, the operation of high-pressure water atomization is stopped, and the bidirectional evaporation heat exchanger operates as an evaporator.

[0024] In an embodiment, when the cold and heat accumulator accumulates heat for discharging cold, two ends of the cold and heat storage device are controlled to be respectively in communication with a high-pressure gas refrigerant circulation pipe and a medium-pressure liquid refrigerant circulation pipe through a control valve. When the cold and heat accumulator accumulates cold for discharging heat, the two ends of the cold and heat storage device are controlled to be respectively in communication with a low-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe through the control valve.

[0025] In an embodiment, when requiring an infrared radiation collector to operate in a heating mode, a regulating valve on a pipeline of the infrared radiation collector is open. When not requiring the infrared radiation collector to operate in the heating mode, the regulating valve on the pipeline of the infrared radiation collector is closed.

[0026] The implementation of the present application has the following technical effects:

[0027] In the single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system provided in the present application, by providing the high-pressure gas refrigerant circulation pipe, the medium-pressure liquid refrigerant circulation pipe, and the low-pressure gas refrigerant circulation pipe as well as by improving the connection method among the bidirectional evaporation heat exchanger, the compressor, the high-pressure gas refrigerant circulation pipe, the medium-pressure liquid refrigerant circulation pipe, and the low-pressure gas refrigerant circulation pipe, and the connection method of the terminal heating assembly and the terminal refrigeration assembly, it can achieve multiple operating modes in a single system, including an independent refrigeration mode, an independent heating mode, a mode of a part of terminals for refrigeration and a part of terminals for heating, and a mode of instantaneous switching between the refrigeration mode and the heating mode at the same terminal. Therefore, it increases the versatility of the whole operation of the multi-split air conditioning system without adding complex refrigerant switching pipeline, meets various comfort demands of different people and refrigeration and heating demands at different terminals, that is, meeting various refrigeration and heating demands in one construction complex by one system. More beneficially, the heat from the cold-consuming terminals can be supplied to the heat-demanding terminals, and the cold from the heat-consuming terminals can be supplied to the cold-demanding terminals. The bidirectional evaporation heat exchanger can be switched between the refrigeration mode and the heating mode according to the demands for both cold and heat of the whole system, equalizing the demands both for cold and heat of the whole system. It further enhances system efficiency, significantly reduces power consumption, and achieves energy conservation and environmental protection in manner of energy transferring and reuse. Further, the components, such as a cold and heat accumulator (e.g., cold and heat accumulating swimming pool) and an infrared radiation collector, may be provided to ensure efficient and safe operation of the system.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a schematic view of a single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to an embodiment of the present application. FIG. 2 is a schematic structural view of a bidirectional evaporation heat exchanger in an embodiment of the present application. FIG. 3 is a schematic communication view of the bidirectional evaporation heat exchanger in refrigeration and heating states in an embodiment of the present application. FIG. 4 is a schematic communication view of a fan coil unit in refrigeration and heating states in an embodiment of the present application. FIG. 5 is a schematic communication view of a cold and heat accumulator in cold accumulating state and heat accumulating states in an embodiment of the present application.

[0029] 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; 106. first port; 107. second port; 2. compressor; 3. high-pressure gas refrigerant circulation pipe; 4. medium-pressure liquid refrigerant circulation pipe; 5. low-pressure gas refrigerant circulation pipe; 6. liquid receiver; 7. regulating valve; 8. control valve; 9. thermometer; 10. fan coil unit; 11. floor heating; 12. domestic hot water tank; 13. cold and heat accumulator; 14. infrared radiation collector; 15. wine cabinet heat exchanger.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] 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.

[0031] As shown in FIG. 1, a single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system in this embodiment includes a bidirectional evaporation heat exchanger 1, a compressor 2, a high-pressure gas refrigerant circulation pipe 3, a medium-pressure liquid refrigerant circulation pipe 4, and a low-pressure gas refrigerant circulation pipe 5. A suction end of the compressor 2 is in communication with the low-pressure gas refrigerant circulation pipe 5, and a discharge end of the compressor 2 is in communication with the high-pressure gas refrigerant circulation pipe 3. The bidirectional evaporation heat exchanger 1 has a first port 106 and a second port 107. The first port 106 is in communication with the high-pressure gas refrigerant circulation pipe 3 and the low-pressure gas refrigerant circulation pipe 5 via a control valve 8. The communication states between the first port 106 and the high-pressure gas refrigerant circulation pipe 3 and between the first port 106 and the low-pressure gas refrigerant circulation pipe 5 are controlled by an on / off operation of the control valve 8. The second port 107 is in communication with the medium-pressure liquid refrigerant circulation pipe 4. A terminal heating assembly is in communication with the high-pressure gas refrigerant circulation pipe 3 and the medium-pressure liquid refrigerant circulation pipe 4, and a terminal refrigeration assembly is in communication with the medium-pressure liquid refrigerant circulation pipe 4 and the low-pressure gas refrigerant circulation pipe 5. The bidirectional evaporation heat exchanger 1 is configured as a single component capable of dynamically switching between a refrigeration mode and a heating mode, or multiple combinations of a refrigeration component and a heating component. When switching between a refrigeration state and a heating state of a terminal assembly is required, the communication states between the terminal assembly and the high-pressure gas refrigerant circulation pipe 3 and between the terminal assembly and the low-pressure gas refrigerant circulation pipe 5 are controlled by the on / off operation of the control valve 8, thereby achieving the switching between the refrigeration mode and the heating mode. A liquid receiver 6 is provided between the second port 107 of the bidirectional evaporation heat exchanger 1 and the medium-pressure liquid refrigerant circulation pipe 4. The liquid receiver 6 is used to store the liquid refrigerant, and a regulating valve 7 is provided between the liquid receiver 6 and the second port 107. The control valve 8 is a three-way valve or two regulating valves 7 that are respectively located on different pipelines.

[0032] In the single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system of the present application, by providing the high-pressure gas refrigerant circulation pipe 3, the medium-pressure liquid refrigerant circulation pipe 4, and the low-pressure gas refrigerant circulation pipe 5 as well as by improving the connection method among the bidirectional evaporation heat exchanger 1, the compressor 2, the high-pressure gas refrigerant circulation pipe, the medium-pressure liquid refrigerant circulation pipe, and the low-pressure gas refrigerant circulation pipe, and the connection method of the terminal heating assembly and the terminal refrigeration assembly, a single system having multiple operating modes can be achieved, including an independent refrigeration mode, an independent heating mode, a mode of a part of terminals for refrigeration and a part of terminals for heating, and a mode of instantaneous switching between the refrigeration mode and the heating mode at the same terminal. Therefore, it increases the versatility of the whole operation of the multi-split air conditioning system without adding complex refrigerant switching pipeline, meets various comfort demands of different people and refrigeration and heating demands at different terminals, that is, meeting various refrigeration and heating demands in one construction complex by one system. More beneficially, the heat from the cold-consuming terminals can be supplied to the heat-demanding terminals, and the cooling from the heat-consuming terminals can be supplied to the cold-demanding terminals. The bidirectional evaporation heat exchanger 1 can be switched between the refrigeration mode and the heating mode according to the demands for both cold and heat of the whole system, equalizing the demands both for cold and heat of the whole system. It further enhances system efficiency, significantly reduces power consumption, and achieves energy conservation and environmental protection in manner of energy transferring and reuse. Further, the components, such as a cold and heat accumulator (e.g., cold and heat accumulating swimming pool 13) and an infrared radiation collector 14, may be provided to ensure efficient and safe operation of the system.

[0033] Further, the compressor 2, the bidirectional evaporation heat exchanger 1, and terminals of the equalization system form a single-stage carbon dioxide circulation system, which can operate in a temperature below the critical point of a condensation temperature (subcritical). In this embodiment, preferably, the carbon dioxide medium is used as the refrigerant medium for the equalization 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 equalization system in this embodiment uses carbon dioxide as the working medium, which can supply cold or heat to higher floors in a vertical direction, and can perform circulating over longer distances in horizontal-floor application so as to operate more indoor units.

[0034] The bidirectional evaporation heat exchanger refers to a single device capable of switching between a refrigeration mode and a heating mode, or a device combining a separate refrigeration component and a separate heating component. Preferably, as shown in FIGS. 2 and 3, the bidirectional evaporation heat exchanger in this embodiment 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 located on one side of the closed housing 100, and the atomizing nozzle 103 and the heat exchange pipe set 102 are located inside the closed housing 100. The centrifugal fan 101 is used to discharge water vapor or air inside the housing. 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 can be opened or closed so as to switch the bidirectional evaporation heat exchanger into the heating state or the refrigeration state. By providing the electric roller shutter 104 in cooperation with the flow direction of the refrigerant, the switching between the refrigeration state and the heating state can be achieved by a 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 roller shutter. In the refrigeration mode of the bidirectional evaporation heat exchanger, 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 heat island effect. The heat exchange occurs inside the closed housing 100 during the refrigeration operation, with almost no air flowing in. Therefore, when the external temperature and humidity are both high, the heat exchange effect is not affected by the external temperature and humidity.

[0035] The left block in FIG. 3 indicates a schematic communication view of the bidirectional evaporation heat exchanger in the refrigeration state, where dashed lines represent for a non-communication state, and arrows represent for flow directions of the refrigerant. During the refrigeration operation (for example, in summer), the electric roller shutter 104 is closed to prevent air from flowing in, the operation of high-pressure water atomization is performed, and the bidirectional evaporation heat exchanger operates 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 1000, generating a required negative pressure environment in an accommodating chamber. The atomized water generated 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. The right block in FIG. 3 indicates a schematic communication view of the bidirectional evaporation heat exchanger in the heating mode, where the dashed lines represent for a non-communication state, and the arrows represent for the flow direction of the refrigerant. During the heating operation (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 operates 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.

[0036] As shown in FIGS. 1 and 4, the terminals include a fan coil unit 10 capable of switching between the refrigeration state and the heating state. One port of the fan coil unit 10 is in communication with the medium-pressure liquid refrigerant circulation pipe 4, and a regulating valve 7 is provided on the pipeline. Another port of the fan coil unit 10 is in communication with the high-pressure gas refrigerant circulation pipe 3 and the low-pressure gas refrigerant circulation pipe 5 through the control valve 8. The communication states between the other port and the high-pressure gas refrigerant circulation pipe 3 and between the another port and the low-pressure gas refrigerant circulation pipe 5 are controlled by the on / off operation of the control valve 8. The regulating valve 7 and thermometer 9 are provided at the one port and the other port of the fan coil unit 10, respectively. The thermometer 9 is used to provide temperature feedback for adjusting the refrigeration and heating capacity. The left block in FIG. 4 indicates a schematic communication view of the fan coil unit 10 in the refrigeration state, where the dashed lines represent for a non-communication state, and the arrows represent for the flow direction of the refrigerant, and the right block in FIG. 4 indicates a schematic communication view of the fan coil unit 10 in the heating state, where the dashed lines represent for a non-communication state, and the arrows represent for the flow direction of the refrigerant.

[0037] As shown in FIG. 1, the terminals include a floor heating 11 that only operates in a heating mode. An inlet end of the floor heating 11 is in communication with the high-pressure gas refrigerant flow pipe 3, and an outlet end of the floor heating 11 is in communication with the medium-pressure liquid refrigerant flow pipe 4. The inlet end of the floor heating 11 is provided with a regulating valve 7, and the outlet end of the floor heating is provided with a check valve, a regulating valve 7, and a thermometer 9. The check valve can prevent the backflow of liquid refrigerant, and the thermometer 9 is used to provide temperature feedback for adjusting the heating capacity. The floor heating 11 is configured as multi-row pipelines installed in multiple rooms in parallel. The pipes of the floor heating 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 a clamp 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, thereby 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 and cools down, and then changes into a liquid state and flows out through the liquid-return pipe. Compared to the conventional floor heating 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.

[0038] As shown in FIG. 1, the terminals include a domestic hot water tank 12 that only operates in a heating mode. An inlet end of the domestic hot water tank 12 is in communication with the high-pressure gas refrigerant circulation pipe 3, and an outlet of the domestic hot water tank 12 is in communication with the medium-pressure liquid refrigerant circulation pipe 4. The inlet end of the domestic hot water tank 12 is provided with the regulating valve 7, and the outlet end is provided with the regulating valve 7 and the thermometer 9. The thermometer 9 is used to provide temperature feedback for adjusting the heating capacity. During normal operation or when the demand for hot water is low, the sensible heat in the discharged gas from the compressor 2 is recycled for domestic hot water production, and in that case, the regulating valves 7 at the inlet and outlet ends are normally open and do not require to be adjusted. When the high demand for hot water cannot be met, the regulating valve 7 at the inlet end of the domestic hot water tank 12 remains open, and the regulating valve 7 at the outlet end can be adjusted according to the set parameter of the outlet temperature sensor.

[0039] As shown in FIGS. 1 and 5, the terminals include a cold and heat accumulator 13 that can switching between the refrigeration state and the heating state. One port of the cold and heat accumulator 13 is in communication with the medium-pressure liquid refrigerant circulation pipe 4, and the regulating valve 7 is provided on the pipeline. The other port of the cold and heat accumulator 13 is respectively connected to the high-pressure gas refrigerant circulation pipe 3 and the low-pressure gas refrigerant circulation pipe 5 through the control valve 8. The communication states between the other port of the cold and heat accumulator 13 and the high-pressure gas refrigerant circulation pipe 3 and between the another port of the cold and heat accumulator 13 and the low-pressure gas refrigerant circulation pipe 5 are controlled by the on / off operation of the control valve 8. The thermometer 9 is provided at the one port of the cold and heat accumulator 13. The thermometer 9 is used to provide temperature feedback for adjusting the refrigeration and heating capacity. The left block in FIG. 5 indicates a schematic communication view of the cold and heat accumulator 13 in the heat accumulating state, where dashed lines represent for a non-communication state, and arrows represent for the flow directions of the refrigerant, and the right block in FIG. 5 indicates a schematic communication view of the cold and heat accumulator 13 in the cold accumulating state, where the dashed lines represent for a non-communication state, and the arrows represent for the flow directions of the refrigerant. The cold and heat accumulator 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 accumulation. When the system cannot meet the high demand for cold in the room, the swimming pool functions as a condenser to discharge the heat in the swimming pool from the room. When the system cannot meet the high demand for heat in the room, the swimming pool functions as an evaporator to extract heat from the swimming pool and supply it to the room.

[0040] As shown in FIG. 5, the terminals include an infrared radiation collector 14. The inlet end of the infrared radiation collector 14 is in communication with the medium-pressure liquid refrigerant circulation pipe 4, and a regulating valve 7 is provided on the pipeline. The outlet end of the infrared radiation collector 14 is in communication with the low-pressure gas refrigerant circulation pipe 5. According to the heat demand of the system, the regulating valve 7 controls the communication states of the infrared radiation collector 14 to supply heat to the system. The infrared radiation collector 14 can collect a part of heat through thermal radiation and can further collect heat using a solar air collector, meeting the heat demand of the system. In this embodiment, the infrared radiation collector 14 includes a guard plate, an absorber plate and an absorber. The absorber plate is located between the absorber and the protective plate. The absorber includes a heat exchange medium inlet end and a heat exchange medium outlet end. The absorber plate is used to transfer the absorbed heat to the refrigerant circulating in the absorber.

[0041] As shown in FIG. 1, the terminals include a wine cabinet heat exchanger 15 that only operates in a refrigeration mode. An inlet end of the wine cabinet heat exchanger 15 is in communication with the medium-pressure liquid refrigerant circulation pipe 4, and a regulating valve 7 is provided on the pipeline. An outlet end of the wine cabinet heat exchanger 15 is in communication with the low-pressure gas refrigerant circulation pipe 5. According to the cold demand of the wine cabinet heat exchanger 15, the refrigerant flow rate is controlled by the regulating valve 7 to supply cold.

[0042] In this embodiment, the regulating valve 7 may be a solenoid valve or an electronic expansion valve.

[0043] A control method of a single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system is further provided in this embodiment. The control method involves setting a discharge pressure and a suction pressure of the compressor 2 of the equalization system. The heating capacity of the equalization system is determined by the discharge pressure, and the cooling capacity of the equalization system is determined by the suction pressure. A control module is provided to monitor whether the discharge pressure and the suction pressure of the compressor are within the set range. If the discharge pressure or the suction pressure of the compressor 2 is out of the set range, whether the heat exchange terminal or the cold exchange terminal operates in the set operation state (i.e., whether the set temperature of the terminal is reached) is first determined. If the heat exchange terminal or the cold exchange terminal does not operate in the set operation state, the number of heat exchange terminals or cold exchange terminals in operation is adjusted to ensure that the discharge pressure and the suction pressure of the compressor are both within the set range. If the heat exchange terminal or the cold exchange terminal operates in the set operation state, one or more of the bidirectional evaporation heat exchanger 1, the cold and heat accumulator 13, and the infrared radiation collector 14 are controlled to operate in a heating state to ensure that the discharge pressure of the compressor is within the set range, or the bidirectional evaporation heat exchanger 1 or the cold and heat accumulator 13 is controlled to be in a refrigeration state to ensure that the suction pressure of the compressor 2 is within the set range. The priority weights among multiple refrigeration and heating terminals may be set to prioritize the refrigeration and heating terminals with higher priority to reach their set temperatures, thereby improving the use comfort level. The system keeps the cold and heat equalization by controlling the refrigeration state and the heating state of the equalization devices, such as the bidirectional evaporation heat exchanger 1, the cold and heat accumulator 2, and the infrared radiation collector 14. Specifically, the set suction pressure and discharge pressure of the compressor 2 remain constant, so that the whole system operates in an efficient state. As such, if the discharge pressure and the suction pressure of the compressor 2 are both within the set range, the operation state of the equalization system remains constant.

[0044] The equalization system uses the bidirectional evaporation heat exchanger in priority to ensure that the suction and discharge pressures of the compressor are within the set range during the switching between the refrigeration state and the cooling state. Further, the cold and heat accumulator plays a crucial equalization role. The cold and heat accumulator may be a swimming pool, which takes the advantage of high latent heat of water to accumulate cold and heat and thus is economical and convenient. The swimming pool may be set in a desired temperature range. When the equalization system has excess heating capacity, the heat from the equalization system is supplemented to the swimming pool to heat it up. When the equalization system has excess cooling capacity, the cold from the equalization system is supplemented to the swimming pool to cool it down. According to the demand of the equalization system, the cold and heat can be further extracted from the swimming pool to use, which ensures efficient operation of the equalization system without wasting excess cold and heat, allowing for on-demand extraction of cold and heat. It can fully utilize nighttime off-peak electricity, reducing the impact on the local power grid, and the infrared radiation collector can further fully utilize daytime solar energy for generating heat.

[0045] Further, when the bidirectional evaporation heat exchanger 1 operates in the refrigeration mode, two ends of the bidirectional evaporation heat exchanger 1 are controlled to be respectively in communication with the high-pressure gas refrigerant flow pipe 3 and the medium-pressure liquid refrigerant flow pipe 4 through the control valve, the electric roller shutter 104 is closed to prevent air from flowing in, the operation of high-pressure water atomization is performed, and the bidirectional evaporation heat exchanger operates as a flash condenser. When the bidirectional evaporation heat exchanger 1 operates in the heating mode, two ends of the bidirectional evaporation heat exchanger 1 are controlled to be respectively in communication with the low-pressure gas refrigerant circulation pipe 5 and the medium-pressure liquid refrigerant flow pipe 4 through the control valve, 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 operates as an evaporator.

[0046] When the cold and heat accumulator 13 accumulates heat for discharging cold, the two ends of the cold and heat storage device 13 are controlled to be respectively in communication with the high-pressure gas refrigerant circulation pipe 3 and the medium-pressure liquid refrigerant circulation pipe 4 through the control valve. When the cold and heat accumulator 13 accumulates cold for discharging heat, the two ends of the cold and heat storage device 13 are controlled to be respectively in communication with the low-pressure gas refrigerant circulation pipe 5 and the medium-pressure liquid refrigerant circulation pipe 4 through the control valve.

[0047] When requiring the infrared radiation collector 14 to operate in a heating mode, the regulating valve on the pipeline of the infrared radiation collector 14 is open. When not requiring the infrared radiation collector 14 to operate in the heating mode, the regulating valve on the pipeline of the infrared radiation collector 14 is closed.

[0048] 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 hybrid refrigeration and heating equalization system, comprising: a bidirectional evaporation heat exchanger; a compressor; a high-pressure gas refrigerant circulation pipe; a medium-pressure liquid refrigerant circulation pipe; and a low-pressure gas refrigerant circulation pipe, wherein a suction end of the compressor is in communication with the low-pressure gas refrigerant circulation pipe, and a discharge end of the compressor is in communication with the high-pressure gas refrigerant circulation pipe; the bidirectional evaporation heat exchanger has a first port and a second port, the first port is in communication with the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe through a control valve, communication states between the first port and the high-pressure gas refrigerant circulation pipe and between the first port and the low-pressure gas refrigerant circulation pipe are controlled by an on / off operation of the control valve; wherein the second port is in communication with the medium-pressure liquid refrigerant circulation pipe; and a terminal heating assembly is in communication with the high-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe, and a terminal refrigeration assembly is in communication with the medium-pressure liquid refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe.

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

3. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein when switching between a refrigeration state and a heating state of the terminal assembly is required, communication states between the terminal assembly and the high-pressure gas refrigerant circulation pipe and between the terminal assembly and the low-pressure gas refrigerant circulation pipe are controlled by an on / off operation of the control valve, so as to achieve the switching between a refrigeration mode and a heating mode.

4. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein a liquid receiver is provided between the second port of the bidirectional evaporation heat exchanger and the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided between the liquid receiver and the second port.

5. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein the control valve is configured as a three-way valve or two regulating valves that are respectively located on different pipelines.

6. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization 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 located on one side of the closed housing, and the atomizing nozzle and the heat exchange pipe set are located inside the closed housing; the centrifugal fan is configured for discharging water vapor or air inside the closed housing, the water vapor or air inside the closed housing is configured 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 bidirectional evaporation heat exchanger into the heating state or the refrigeration state.

7. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 6, wherein a grid plate is provided on one side of the electric roller shutter.

8. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein the terminals comprise a fan coil unit capable of switching between the refrigeration state and the heating state, one port of the fan coil unit is in communication with the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on a pipeline; the other port of the fan coil unit is in communication with the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe through the control valve, and communication states between the other port and the high-pressure gas refrigerant circulation pipe and between the other port and the low-pressure gas refrigerant circulation pipe are controlled by an on / off operation of the control valve; and the regulating valve and a thermometer are provided at the one port and the other port of the fan coil unit, respectively.

9. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein the terminals comprise a floor heating that is only operable in a heating mode, an inlet end of the floor heating is in communication with the high-pressure gas refrigerant flow pipe, and an outlet end of the floor heating is in communication with the medium-pressure liquid refrigerant flow pipe; and the inlet end of the floor heating is provided with a regulating valve, and the outlet end of the floor heating is provided with a check valve, a regulating valve, and a thermometer.

10. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 9, wherein the floor heating is configured as multi-row pipelines installed in rooms in parallel, pipes of the floor heating comprise a gas-supply pipe, a liquid-return pipe, and a plurality of branch pipes, wherein the plurality of branch pipes are continuously bent outward and are coiled in a floor; and 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, wherein the plurality of branch pipes are fixed to the steel mesh by a clamp and abut against a coiled-pipe layer; and the reflective layer is made of aluminum foil or extruded insulation boards having aluminum foil, and the thermal storage layer is formed by a mixture of cobblestone, sand, and cement.

11. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein the terminals comprise a domestic hot water tank that is only operable in a heating mode, an inlet end of the domestic hot water tank is in communication with the high-pressure gas refrigerant circulation pipe, and an outlet end of the domestic hot water tank is in communication with the medium-pressure liquid refrigerant circulation pipe; and the inlet end of the domestic hot water tank is provided with a regulating valve, and the outlet end of the domestic hot water tank is provided with a regulating valve and a thermometer.

12. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein the terminals comprise a cold and heat accumulator that can switching between the refrigeration state and the heating state, one port of the cold and heat accumulator is in communication with the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on a pipeline; the other port of the cold and heat accumulator is connected to the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe through the control valve; and communication states between the other port of the cold and heat accumulator and the high-pressure gas refrigerant circulation pipe and between the other port of the cold and heat accumulator and the low-pressure gas refrigerant circulation pipe are controlled by an on / off operation of the control valve, and a thermometer is provided at the one port of the cold and heat accumulator.

13. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein the terminals comprise an infrared radiation collector, an inlet end of the infrared radiation collector is in communication with the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on a pipeline; and an outlet end of the infrared radiation collector is in communication with the low-pressure gas refrigerant circulation pipe.

14. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 1, wherein the terminals comprise a wine cabinet heat exchanger that is only operable in a refrigeration mode, an inlet end of the wine cabinet heat exchanger is in communication with the medium-pressure liquid refrigerant circulation pipe and a regulating valve is provided on a pipeline; and an outlet end of the wine cabinet heat exchanger is in communication with the low-pressure gas refrigerant circulation pipe.

15. The single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system according to claim 4, wherein the regulating valve is a solenoid valve or an electronic expansion valve.

16. A control method of a single-stage subcritical carbon dioxide multi-split hybrid refrigeration and heating equalization system, comprising: setting a discharge pressure and a suction pressure of a compressor of the equalization system, wherein a heating capacity of the equalization system is determined by the discharge pressure, a cooling capacity of the equalization system is determined by the suction pressure, and a control module is provided to monitor whether the discharge pressure and the suction pressure of the compressor are within a set range; if the discharge pressure or the suction pressure of the compressor is out of the set range, first determining whether a heat exchange terminal or a cold exchange terminal operates in a set operation state, if the heat exchange terminal or the cold exchange terminal does not operate in the set operation state, the number of heat exchange terminal or cold exchange terminal in operation is adjusted to ensure that the discharge pressure and the suction pressure of the compressor are both within the set range; if the heat exchange terminal or the cold exchange terminal operates in the set operation state, one or more of a bidirectional evaporation heat exchanger, a cold and heat accumulator, and an infrared radiation collector are controlled to operate in a heating state to ensure that the discharge pressure of the compressor is within the set range, or, the bidirectional evaporation heat exchanger or the cold and heat accumulator is controlled to be in a refrigeration state to ensure that the suction pressure of the compressor is within the set range.

17. The control method according to claim 16, wherein when the bidirectional evaporation heat exchanger operates in a refrigeration mode, two ends of the bidirectional evaporation heat exchanger are controlled to be respectively in communication with a high-pressure gas refrigerant flow pipe and a medium-pressure liquid refrigerant flow pipe through a control valve, an electric roller shutter is closed to prevent air from flowing in, an operation of high-pressure water atomization is performed, and the bidirectional evaporation heat exchanger operates as a flash condenser; when the bidirectional evaporation heat exchanger operates in a heating mode, the two ends of the bidirectional evaporation heat exchanger are controlled to be respectively in communication with a low-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant flow pipe through the control valve, the electric roller shutter is retracted to allow air flowing in, the operation of high-pressure water atomization is stopped, and the bidirectional evaporation heat exchanger operates as an evaporator.

18. The control method according to claim 16, wherein when the cold and heat accumulator accumulates heat for discharging cold, two ends of the cold and heat storage device are controlled to be respectively in communication with a high-pressure gas refrigerant circulation pipe and a medium-pressure liquid refrigerant circulation pipe through a control valve; and when the cold and heat accumulator accumulates cold for discharging heat, the two ends of the cold and heat storage device are controlled to be respectively in communication with a low-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe through y the control valve.

19. The control method according to claim 16, wherein when an infrared radiation collector is required to operate in a heating mode, a regulating valve on a pipeline of the infrared radiation collector is open; and when the infrared radiation collector is not required to operate in the heating mode, the regulating valve on the pipeline of the infrared radiation collector is closed.

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