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

Single-stage subcritical carbon dioxide multi-connected mixed cooling and heating balance system and control method Technical Field

[0001] The present invention relates to the field of air conditioning, and in particular to a single-stage subcritical carbon dioxide multi-connected mixed cooling and heating balance system and a control method. Background Art

[0002] The construction industry is becoming a major force in addressing climate change and reducing carbon emissions. Statistics show that building energy consumption accounts for approximately one-third of total societal energy consumption. Reducing this energy consumption will significantly improve overall energy consumption and have a significant impact on energy conservation, emission reduction, and environmental protection. Vigorously promoting energy-efficient buildings, continuously improving building energy efficiency through measures such as raising energy-saving standards, implementing renovation projects, strengthening supervision, and promoting renewable energy, has become a trend. Air conditioning energy consumption accounts for a significant proportion of building energy consumption. Air conditioning is frequently used during winter and summer. In today's energy-scarce environment, with high energy consumption and prominent environmental pollution, energy conservation and emission reduction are essential for sustainable social development. The main components of existing multi-split air conditioners include a compressor for heating and a condenser for cooling. The heat exchange principle is as follows: the compressor compresses the refrigerant (ammonia or Freon) into a high-pressure saturated gas, which is then condensed by the condenser. Because condensed ammonia or Freon cannot circulate quickly within the pipeline, it must first be throttled by a throttling device before entering the evaporator to cool to the set temperature before being transported to the energy-consuming device for heat exchange. This means that during heat exchange, the refrigerant must first be compressed to a temperature higher than the set temperature before being cooled, significantly increasing the energy consumption of the compressor and condenser, resulting in low heat exchange efficiency. Furthermore, Freon emissions can exacerbate the greenhouse effect, and ammonia is explosive, both of which are inconsistent with the national environmental protection, energy conservation, and safety principles advocated by the government.

[0003] As living standards improve, the demand for cooling and heating within a building is also changing. Multi-split air conditioners utilize a refrigeration cycle to cool or heat indoor spaces, providing unified cooling in summer and unified heating in winter. This is the fundamental function of air conditioning. However, this also presents a problem: once cooling is enabled, all air conditioners are in cooling mode, and once heating is enabled, all air conditioners are in heating mode. During transitional seasons, such as in southern China where temperatures fluctuate between cold and hot, different groups have different thermal comfort requirements. For example, young and middle-aged people with better physiques may feel a bit hot and require cooling, while the elderly and children may feel cold and require heating. Currently, most standard multi-split air conditioners on the market can only operate in either cooling or heating mode. If simultaneous cooling and heating are required in different rooms within a single system, two separate air conditioning systems must be installed, increasing construction costs.

[0004] Therefore, the motivation for the invention is to provide a single-stage subcritical carbon dioxide multi-connected hybrid cooling and heating balance system that can provide cooling and heating at the same time with one system, facilitates switching between cooling and heating, achieves balanced utilization of cooling and heat, and is energy-saving and environmentally friendly.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system and control method that can provide cooling and heating at the same time with one system, facilitate switching between cooling and heating, achieve balanced utilization of cooling and heat, and be energy-saving and environmentally friendly.

[0007] The single-stage subcritical carbon dioxide multi-unit mixed cooling and heating balance system provided by the present invention has the following technical solutions:

[0008] A single-stage subcritical carbon dioxide multi-unit mixed hot and cold balancing system includes a two-way evaporative 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. The suction end of the compressor is connected to the low-pressure gas refrigerant circulation pipe, and the exhaust end of the compressor is connected to the high-pressure gas refrigerant circulation pipe; the two-way evaporative heat exchanger is provided with a first port and a second port, the first port is connected to the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe respectively through a control valve component, and the connection state of the first port with the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe is controlled according to the opening and closing of the control valve component, the second port is connected to the medium-pressure liquid refrigerant circulation pipe, the terminal heating component is connected to the high-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively, and the terminal refrigeration component is connected to the medium-pressure liquid refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe respectively.

[0009] Furthermore, the compressor, the two-way evaporation heat exchanger and the terminal of the equalization system constitute a single-stage carbon dioxide circulation system, and the single-stage carbon dioxide circulation system operates below the critical point of the condensation temperature.

[0010] Furthermore, the terminal assembly that needs to switch between cooling state and heating state controls the connection state between the terminal assembly and the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe by opening and closing the control valve component to complete the switching between cooling and heating.

[0011] Furthermore, a liquid reservoir is provided between the second port of the bidirectional evaporative heat exchanger and the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided between the liquid reservoir and the second port.

[0012] Furthermore, the control valve component is a three-way control valve or two regulating valve groups respectively arranged on different pipelines.

[0013] Furthermore, the bidirectional evaporative heat exchanger includes a closed shell, a centrifugal fan, a heat exchange tube group and an atomizing nozzle. The centrifugal fan is provided on one side of the closed shell, and the atomizing nozzle and the heat exchange tube group are arranged in the closed shell. The centrifugal fan is used to suck water vapor or air in the shell, and the water vapor or air in the closed shell exchanges heat with the refrigerant flowing in the heat exchange tube group. An electric roller shutter is provided on one side of the closed shell, and the opening or closing of the electric roller shutter is used to switch the heating state or cooling state of the heat exchanger.

[0014] Furthermore, a mesh plate is provided on one side of the rolling shutter.

[0015] Furthermore, the terminal includes a fan coil unit that can switch between cooling state and heating state. One interface of the fan coil unit is connected to the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on the pipeline. The other interface is connected to the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe respectively through the control valve component. The connection state of the port and the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe is controlled according to the opening and closing of the control valve component; a thermometer and a regulating valve are provided at the interface of the fan coil unit.

[0016] Furthermore, the terminal includes a floor heating system that only generates heat. The inlet of the floor heating system is connected to a high-pressure gas refrigerant flow pipe, and the outlet is connected to a medium-pressure liquid refrigerant flow pipe. The inlet of the floor heating system is provided with a regulating valve, and the outlet is provided with a one-way valve, a regulating valve, and a thermometer.

[0017] Furthermore, the floor heating is a parallel multi-row pipe system installed in multiple rooms. The floor heating pipes include an air supply pipe, a liquid return pipe and several branch pipes. The branch pipes are bent outward continuously for multiple circles and coiled in the floor. The floor includes a concrete slab, a reflective layer, a steel wire mesh, a heat storage layer and a floor tile layer laid in sequence. The branch pipes are fixed to the steel wire mesh by a clamp and abut against the coil layer. The reflective layer is made of aluminum foil or an extruded insulation board with aluminum foil, and the heat storage layer is a mixture of pebbles, sand and cement.

[0018] Furthermore, the terminal includes a domestic hot water tank for heating only, the inlet of the domestic hot water tank being connected to the high-pressure gas refrigerant flow pipe, and the outlet being connected to the medium-pressure liquid refrigerant flow pipe. The inlet of the domestic hot water tank is provided with a regulating valve, and the outlet is provided with a regulating valve and a thermometer.

[0019] Furthermore, the terminal includes a cold and heat storage device that can switch between cooling and heating states. One interface of the cold and heat storage device is connected to the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on the pipeline. The other interface is connected to the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe respectively through the control valve component. The connection state of the port and the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe is controlled according to the opening and closing of the control valve component; a thermometer is provided at the interface of the cold and heat storage device.

[0020] Furthermore, the end includes an infrared radiation collector, the inlet end of the infrared radiation collector is connected to the medium-pressure liquid refrigerant circulation pipe, a regulating valve is provided on the pipeline, and the outlet end is connected to the low-pressure gas refrigerant circulation pipe.

[0021] Furthermore, the end includes a wine cabinet heat exchanger for cooling only, the inlet end of the wine cabinet heat exchanger is connected to the medium-pressure liquid refrigerant circulation pipe, a regulating valve is provided on the pipeline, and the outlet end is connected to the low-pressure gas refrigerant circulation pipe.

[0022] Furthermore, the regulating valve is a solenoid valve or an electronic expansion valve.

[0023] A control method for a single-stage subcritical carbon dioxide multi-split hybrid hot and cold balancing system sets the exhaust pressure and suction pressure of the compressor for the balancing system. The exhaust pressure determines the heating capacity of the balancing system, and the suction pressure determines the cooling capacity of the balancing system. The control module monitors whether the exhaust pressure and suction pressure of the compressor are within a set range. If the exhaust pressure or suction pressure of the compressor is not within the set range, it is first determined whether the heat exchange end or the cold exchange end has reached a set operating state. If the operating state is not reached, the number of heat exchange ends or the number of cold exchange ends is started to meet the requirement that the exhaust pressure and suction pressure of the compressor are within the set range; if the heat exchange end or the cold exchange end is both in the set operating state, one or more of the two-way evaporative heat exchanger, the cold heat storage device, and the infrared radiation collector are controlled to be in a heating state to meet the requirement that the exhaust pressure of the compressor is within the set range, or the two-way evaporative heat exchanger or the cold heat storage device is controlled to be in a cooling state to meet the requirement that the suction pressure of the compressor is within the set range.

[0024] Furthermore, when the two-way evaporative heat exchanger is cooling, the control valve is used to control the two ends of the two-way evaporative heat exchanger to be connected to the high-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively, the electric roller shutter is closed to prevent air from entering, the high-pressure atomized water is in operation, and the two-way evaporative heat exchanger is used as a flash condenser; when heating, the control valve is used to control the two ends of the two-way evaporative heat exchanger to be connected to the low-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively, the electric roller shutter is retracted to allow air to enter, the high-pressure atomized water is closed, and the two-way evaporative heat exchanger is used as an evaporator.

[0025] Furthermore, when the cold-heat storage accumulator stores heat and takes out cold, the control valve component controls the two ends of the cold-heat storage accumulator to be connected to the high-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively; when storing cold and taking out heat, the control valve component controls the two ends of the cold-heat storage accumulator to be connected to the low-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively.

[0026] Furthermore, when the infrared radiation collector needs to generate heat, the regulating valve on the infrared radiation collector pipeline is opened, and when heating is not required, the regulating valve on the infrared radiation collector pipeline is closed.

[0027] The implementation of the present invention includes the following technical effects:

[0028] The single-stage subcritical carbon dioxide multi-split hybrid cooling and heating balance system of the present invention, by providing high-pressure gas refrigerant flow pipes, medium-pressure liquid refrigerant flow pipes, and low-pressure gas refrigerant flow pipes, as well as improving the connection method between the bidirectional evaporative heat exchanger, the compressor, the high-, medium-, and low-pressure pipes, and the terminal heating and cooling components, can achieve multiple operating modes within a single system, including independent cooling, independent heating, partial terminal cooling and partial terminal heating, and the ability for the same terminal to switch between cooling and heating modes at any time. This improves the overall operational diversity of the multi-split air conditioning system without adding complex refrigerant switching piping, addresses the different comfort needs of different groups of people, and the cooling and heating requirements of different terminals. In other words, a single system can meet the various cooling and heating needs of a building complex. More advantageously, heat from the cooling terminals can be used to provide heat to the heating terminals, and cooling from the heating terminals can be used to provide cooling to the cooling terminals. The bidirectional evaporative heat exchanger switches between cooling and heating modes according to the cooling and heating requirements of the entire system, thereby balancing the cooling and heating requirements of the entire system. By transporting and reusing energy, the system's efficiency is further improved, power consumption is significantly reduced, and energy conservation and environmental protection are truly achieved. Furthermore, components such as cold and heat storage devices (such as cold and heat storage swimming pools) and infrared radiation collectors can be installed to ensure the system's efficient and safe operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic diagram of a single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to an embodiment of the present invention.

[0030] FIG2 is a schematic structural diagram of a bidirectional evaporative heat exchanger according to an embodiment of the present invention.

[0031] FIG3 is a schematic diagram showing the connection between the cooling state and the heating state of the bidirectional evaporative heat exchanger according to an embodiment of the present invention.

[0032] FIG4 is a schematic diagram showing the connection between the fan coil unit in the cooling state and the heating state according to an embodiment of the present invention.

[0033] FIG5 is a schematic diagram showing the connection between the heat storage state and the cold storage state of the cold-heat storage device according to an embodiment of the present invention.

[0034] In the figure: 1. Bidirectional evaporative heat exchanger; 100. Closed shell; 101. Centrifugal fan; 102. Heat exchange tube group; 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 storage tank; 7. Regulating valve; 8. Control valve component; 9. Thermometer; 10. Fan coil unit; 11. Floor heating; 12. Domestic hot water tank; 13. Cold and heat storage device; 14. Infrared radiation collector; 15. Wine cabinet heat exchanger. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to embodiments and drawings. It should be noted that the described embodiments are only intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0036] 1 , the single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system provided in this embodiment includes a bidirectional evaporative heat exchanger 1, a compressor 2, a high-pressure gas refrigerant circulation pipe 3, an intermediate-pressure liquid refrigerant circulation pipe 4, and a low-pressure gas refrigerant circulation pipe 5. The suction end of the compressor 2 is connected to the low-pressure gas refrigerant circulation pipe 5, and the discharge end of the compressor 2 is connected to the high-pressure gas refrigerant circulation pipe 3. The bidirectional evaporative heat exchanger 1 is provided with a first port 106 and a second port 107. The first port 106 is connected to the high-pressure gas refrigerant circulation pipe 3 and the low-pressure gas refrigerant circulation pipe 5, respectively, through a control valve 8. The opening and closing of the control valve 8 controls the communication state of the first port 106 with the high-pressure gas refrigerant circulation pipe 3 and the low-pressure gas refrigerant circulation pipe 5, and the second port 107 is connected to the intermediate-pressure liquid refrigerant circulation pipe 4. The terminal heating component is connected to the high-pressure gas refrigerant circulation pipe 3 and the intermediate-pressure liquid refrigerant circulation pipe 4, respectively, and the terminal cooling component is connected to the intermediate-pressure liquid refrigerant circulation pipe 4 and the low-pressure gas refrigerant circulation pipe 5, respectively. The bidirectional evaporative heat exchanger 1 is a component that can achieve dynamic switching between cooling and refrigeration, or a combination of multiple cooling components and heating components. The terminal component that needs to switch between cooling and heating states controls the connection between the terminal component and the high-pressure gas refrigerant circulation pipe 3 and the low-pressure gas refrigerant circulation pipe 5 by opening and closing the control valve component 8, thereby completing the switching between cooling and heating. A liquid reservoir 6 is provided between the second port 107 of the bidirectional evaporative heat exchanger 1 and the medium-pressure liquid refrigerant circulation pipe 4. The liquid reservoir 6 is used to store liquid refrigerant, and a regulating valve 7 is provided between the liquid reservoir 6 and the second port 107. The control valve component 8 is a three-way control valve or two regulating valves 7 groups provided on different pipelines.

[0037] The single-stage subcritical carbon dioxide multi-split hybrid cooling and heating balance system of the present invention, by providing a high-pressure gas refrigerant flow pipe 3, a medium-pressure liquid refrigerant flow pipe 4, and a low-pressure gas refrigerant flow pipe 5, and improving the connection method between the bidirectional evaporative heat exchanger 1, the compressor 2, and the high, medium, and low-pressure pipes, as well as the connection method of the terminal heating component and the terminal cooling component, can realize multiple operating modes in a single system, including independent cooling, independent heating, partial terminal cooling and partial terminal heating, and the same terminal switching between cooling and heating modes at any time. Without adding complex refrigerant switching piping, the overall operational diversity of the multi-split air conditioning system is enhanced, and the different comfort needs of different groups of people and the cooling and heating needs of different terminals are addressed. In other words, a single system can meet the various cooling and heating needs of a building complex. More advantageously, the heat in the cooling terminal can be used to provide heat to the heating terminal, and the cooling in the heating terminal can be used to provide cooling to the cooling terminal. The bidirectional evaporative heat exchanger 1 switches between cooling and heating modes according to the cooling and heating needs of the entire system, thus balancing the cooling and heating needs of the entire system. By transporting and reusing energy, the efficiency of the system is further improved, power consumption is greatly reduced, and energy conservation and environmental protection are truly achieved. Furthermore, components such as cold and heat storage devices (such as cold and heat storage swimming pools 13) and infrared radiation collectors 14 can also be provided to ensure efficient and safe operation of the system.

[0038] Furthermore, the compressor 2, the two-way evaporative heat exchanger 1 and the terminal of the balancing system constitute a single-stage carbon dioxide circulation system, and the single-stage carbon dioxide circulation system operates below the critical point of the condensation temperature (subcritical). This embodiment preferably uses carbon dioxide as the refrigerant medium of the balancing system. Using carbon dioxide as a circulating working fluid has the advantages of large pressure difference, good fluidity, low density, and transcritical phase change, and the effect is more obvious when used in high-rise buildings. The single-stage carbon dioxide circulation system using carbon dioxide as a single circulating working fluid, the meaning of single stage is different from the cascade system, and only carbon dioxide is used for circulation without cascading. The balancing system of this embodiment uses carbon dioxide as a working fluid, which can provide cooling or heating for higher floors in the vertical height, and can circulate a longer distance when used on flat floors, and can drive more indoor units to work.

[0039] A bidirectional evaporative heat exchanger refers to a device capable of switching between cooling and heating modes, or a combination of a separate cooling component and a separate heating component. Preferably, as shown in Figures 2 and 3 , the bidirectional evaporative heat exchanger of this embodiment includes a closed housing 100, a centrifugal fan 101, a heat exchange tube assembly 102, and an atomizing nozzle 103. The centrifugal fan 101 is disposed on one side of the closed housing 100, and the atomizing nozzle 103 and heat exchange tube assembly 102 are disposed within the closed housing 100. The centrifugal fan 101 is used to draw water vapor or air from the housing, which then exchanges heat with the refrigerant flowing through the heat exchange tube assembly 102. A motorized roller shutter 104 is disposed on one side of the closed housing 100. Opening or closing the motorized roller shutter 104 switches the heat exchanger between heating and cooling modes. By providing the motorized roller shutter 104 and controlling the refrigerant flow direction, switching between heating and cooling modes can be accomplished using a single device, reducing equipment cost and system complexity. The atomizing nozzle 103 is connected to the high-pressure water pipe, and the atomizing nozzle 103 is used to produce atomized water. The centrifugal fan 101 is a backward-inclined centrifugal fan 101. A mesh plate 105 is provided on one side of the roller shutter. In the cooling mode, the water vapor after heat exchange in the two-way evaporative heat exchanger is not circulated or recovered, but is directly discharged into the atmosphere. Since heat is mainly converted into internal energy during the decomposition of water microclusters, the temperature of the discharged water vapor is not high and no heat island effect will be generated. During cooling, heat exchange is carried out in the closed shell 100, and almost no air is introduced. When the external temperature and humidity are high, the heat exchange effect will not be affected by the external temperature and humidity.

[0040] The left frame of Figure 3 is a connection diagram of the two-way evaporative heat exchanger in the cooling state. The dotted line indicates that it is not connected, and the arrow indicates the direction of refrigerant flow. During cooling (such as summer), the electric roller shutter 104 is closed and no air is allowed to enter. The high-pressure atomized water is running, and the two-way evaporative heat exchanger is used as a flash condenser. After the electric roller shutter 104 is closed, the centrifugal fan 101 continuously discharges the water vapor in the closed shell 100 out of the closed shell 100, so that the required negative pressure environment is formed in the accommodating chamber. The atomized water generated by the atomizing nozzle 103 exchanges heat with the high-temperature refrigerant in the heat exchange tube group 102 in the negative pressure environment of the accommodating chamber. The water vapor quickly flashes and changes from water mist to steam, absorbing heat, thereby reducing the ambient temperature in the closed shell 100 and liquefying and condensing the refrigerant. The right frame of Figure 3 is a connection diagram of the two-way evaporative heat exchanger in the heating state. The dotted line indicates that it is not connected, and the arrow indicates the direction of refrigerant flow. During heating (such as in winter), the electric roller shutter 104 is retracted to allow air in, the high-pressure atomized water is turned off, and the two-way evaporative heat exchanger is used as an evaporator; after the electric roller shutter 104 is retracted and opened, the outside air exchanges heat with the low-temperature refrigerant in the heat exchange tube group 102, and the refrigerant vaporizes and evaporates.

[0041] As shown in Figures 1 and 4 , the terminal includes a fan coil unit 10 capable of switching between cooling and heating modes. One port of the fan coil unit 10 is connected to a medium-pressure liquid refrigerant flow pipe 4, with a regulating valve 7 installed on the pipe. The other port is connected to a high-pressure gas refrigerant flow pipe 3 and a low-pressure gas refrigerant flow pipe 5, respectively, via a control valve 8. The opening and closing of the control valve 8 controls the connection between this port and the high-pressure gas refrigerant flow pipe 3 and the low-pressure gas refrigerant flow pipe 5. A thermometer 9 and a regulating valve 7 are installed at the port of the fan coil unit 10. The thermometer 9 is used to provide temperature feedback and adjust the cooling and heating capacity. The left frame of Figure 4 shows a schematic diagram of the fan coil unit 10 in the cooling mode, with dashed lines indicating disconnection and arrows indicating the direction of refrigerant flow. The right frame of Figure 4 shows a schematic diagram of the fan coil unit 10 in the heating mode, with dashed lines indicating disconnection and arrows indicating the direction of refrigerant flow.

[0042] As shown in Figure 1, the end includes a floor heating 11 that only generates heat. The inlet end of the floor heating 11 is connected to the high-pressure gas refrigerant circulation pipe 3, and the outlet end is connected to the medium-pressure liquid refrigerant circulation pipe 4. The inlet end of the floor heating 11 is provided with a regulating valve 7, and the outlet end is provided with a one-way valve, a regulating valve 7 and a thermometer 9. The one-way valve can prevent the liquid refrigerant from flowing back, and the thermometer 9 is used to feedback the temperature and adjust the heating amount. The floor heating 11 is a parallel multi-row pipeline set up in multiple rooms. The floor heating pipe includes an air supply pipe, a return liquid pipe and a number of branch pipes. The branch pipes are bent outward continuously for multiple turns and are entrenched in the floor. The floor includes a concrete slab, a reflective layer, a steel wire mesh, a heat storage layer and a floor tile layer laid in sequence. The branch pipes are fixed to the steel wire mesh by a clamp and abut against the coil layer. Specifically, the reflective layer is made of aluminum foil or an extruded insulation board with aluminum foil. The aluminum foil reflects the heat radiated by the branch pipe and transmits it to the upper end of the reflective layer to achieve uniform heat conduction. The heat storage layer is made of a mixture of pebbles, sand and cement. Pebbles have good thermal conductivity and a smooth surface without edges and corners, which is conducive to protecting the branch pipes while fully transferring heat. Carbon dioxide is used as a medium to transfer heat to the ground. Carbon dioxide has very good thermal conductivity. During the heat transfer process, carbon dioxide enters the branch pipe from the gas supply pipe in the form of gas. After exchanging heat with the floor in the branch pipe, the temperature drops and it is converted into liquid and flows out from the return pipe. Compared with traditional floor heating with water as the medium, carbon dioxide directly heats the ground, eliminating the intermediate transfer link of Freon heat transfer to water and water transfer to the ground. This is conducive to improving heat transfer efficiency and reducing heat transfer loss. It can provide a more suitable temperature for the room and make the heat more evenly distributed in the room, which is conducive to improving heat utilization efficiency and reducing the cost of using floor heating.

[0043] As shown in Figure 1, the terminal includes a domestic hot water tank 12 for heating only. The inlet end of the domestic hot water tank 12 is connected to the high-pressure gas refrigerant circulation pipe 3, and the outlet end is connected to the medium-pressure liquid refrigerant circulation pipe 4. The inlet end of the domestic hot water tank 12 is provided with a regulating valve 7, and the outlet end is provided with a regulating valve 7 and a thermometer 9. The thermometer 9 is used to feedback the temperature and adjust the heating capacity. When the system is operating normally or when the demand for hot water is low, the sensible heat of the exhaust of the compressor 2 is recovered to produce domestic hot water. The inlet and outlet regulating valves 7 of the domestic hot water tank 12 are both in the normally open state and are not adjusted. When the demand for hot water is large and cannot be met, the inlet regulating valve 7 of the domestic hot water tank 12 is in the normally open state, and the outlet regulating valve 7 is adjusted according to the parameter value set by the outlet temperature sensor.

[0044] As shown in Figures 1 and 5 , the terminal includes a cold-heat storage accumulator 13 capable of switching between cooling and heating modes. One port of the cold-heat storage accumulator 13 is connected to the medium-pressure liquid refrigerant flow pipe 4, with a regulating valve 7 installed on the pipe. The other port is connected to the high-pressure gas refrigerant flow pipe 3 and the low-pressure gas refrigerant flow pipe 5, respectively, via a control valve 8. The opening and closing of the control valve 8 controls the connection between this port and the high-pressure gas refrigerant flow pipe 3 and the low-pressure gas refrigerant flow pipe 5. A thermometer 9 is installed at the port of the cold-heat storage accumulator 13. The thermometer 9 is used to provide temperature feedback and adjust the cooling and heating capacity. The left frame of Figure 5 shows a schematic diagram of the cold-heat storage accumulator 13 in its heat storage state. The dashed line indicates disconnection, and the arrows indicate the refrigerant flow direction. The right frame of Figure 5 shows a schematic diagram of the cold-heat storage accumulator 13 in its cold storage state. The dashed line indicates disconnection, and the arrows indicate the refrigerant flow direction. The cold and heat storage device can be a swimming pool. The system can not only heat the pool water to a temperature suitable for swimming; it also has the function of storing cold and heat. When the room has a large cooling demand and the system cannot meet the usage demand, the swimming pool acts as a condenser and discharges the heat from the room; when the room has a large heat demand and the system cannot meet the usage demand, the swimming pool acts as an evaporator and extracts heat from the pool to supply the room.

[0045] As shown in Figure 5, the end includes an infrared radiation collector 14. The inlet end of the infrared radiation collector 14 is connected to the medium-pressure liquid refrigerant circulation pipe 4. A regulating valve 7 is provided on the pipeline, and the outlet end is connected to the low-pressure gas refrigerant circulation pipe 5. According to the heat demand of the system, the connection state of the infrared radiation collector 14 is controlled by the regulating valve 7 to provide heat for the system. The infrared radiation collector 14 can collect part of the heat by thermal radiation, and can also use the air energy collector to collect heat, thereby ensuring the heating demand of the system. In this embodiment, the infrared radiation collector 14 includes a protective plate, a heat absorbing plate and a plate core. The heat absorbing plate is located between the plate core and the protective plate. The plate core includes a heat exchange medium inlet end and a heat exchange medium outlet end. The heat absorbing plate is used to transfer the absorbed heat to the refrigerant circulating in the plate core.

[0046] As shown in Figure 1, the terminal includes a wine cooler heat exchanger 15, which only functions as a cooling device. The inlet of wine cooler heat exchanger 15 is connected to a medium-pressure liquid refrigerant flow pipe 4, which is equipped with a regulating valve 7. The outlet of wine cooler heat exchanger 15 is connected to a low-pressure gas refrigerant flow pipe 5. The regulating valve 7 controls the refrigerant flow rate based on the cooling capacity required by wine cooler heat exchanger 15 to achieve cooling.

[0047] In this embodiment, the regulating valve 7 can be a solenoid valve or an electronic expansion valve.

[0048] This embodiment also provides a control method for a single-stage subcritical carbon dioxide multi-split hybrid heating and cooling balancing system. The exhaust pressure and suction pressure of compressor 2 are set for the balancing system. The exhaust pressure determines the heating capacity of the balancing system, and the suction pressure determines the cooling capacity of the balancing system. The control module monitors whether the exhaust pressure and suction pressure of the compressor are within a set range. If the exhaust pressure or suction pressure of compressor 2 is not within the set range, it is first determined whether the heat exchange end or the cooling end has reached a set operating state (i.e., whether the set end temperature has been reached). If the operating state has not been reached, the number of heat exchange ends or cooling ends is started to ensure that the exhaust pressure and suction pressure of the compressor are within the set range. If both the heat exchange end or the cooling end are in the set operating state, one or more of the bidirectional evaporative heat exchanger 1, the cold heat storage accumulator 13, and the infrared radiation collector 14 are controlled to be in a heating state to ensure that the exhaust pressure of the compressor is within the set range, or the bidirectional evaporative heat exchanger 1 or the cold heat storage accumulator 13 is controlled to be in a cooling state to ensure that the suction pressure of compressor 2 is within the set range. Priority weights can be set for multiple cooling and heating terminals, ensuring that the cooling and heating terminals with the highest priority reach the set temperature, improving user comfort. The system's cooling and heating balance is maintained by controlling the cooling and heating states of balancing devices such as the bidirectional evaporative heat exchanger 1, the cold and heat storage device 2, and the infrared radiation collector 14. Specifically, the suction and discharge pressures set for compressor 2 remain unchanged, ensuring that the entire system operates efficiently. If the discharge pressure or suction pressure of compressor 2 is within the set range, the operating state of the balancing system remains unchanged.

[0049] The balancing system prioritizes the use of a bidirectional evaporative heat exchanger, switching between cooling and heating modes to ensure the compressor's suction and discharge pressures remain within the set range. Furthermore, a cold and heat storage device plays an important balancing role. This storage device can be a swimming pool, leveraging the large latent heat of water to store heat and cool. This is economical and convenient. The swimming pool can be set to a desired temperature range. When the balancing system has excess heat, it is fed into the pool to heat it. When the balancing system has excess cold, it is fed into the pool to cool it. Depending on the needs of the balancing system, heat and cold can be withdrawn from the pool. This ensures efficient operation of the balancing system while minimizing the waste of excess cold and heat, allowing cooling and heating to be taken as needed. This system can also fully utilize nighttime off-peak electricity to mitigate the impact on the local power grid. Infrared radiation collectors can also fully utilize daytime solar heating.

[0050] Furthermore, when the bidirectional evaporative heat exchanger 1 is cooling, the control valve is used to control the two ends of the bidirectional evaporative heat exchanger 1 to be connected to the high-pressure gas refrigerant circulation pipe 3 and the medium-pressure liquid refrigerant circulation pipe 4 respectively, the electric roller shutter 104 is closed to prevent air from entering, the high-pressure atomized water is running, and the bidirectional evaporative heat exchanger 1 is used as a flash condenser; when heating, the control valve is used to control the two ends of the bidirectional evaporative heat exchanger 1 to be connected to the low-pressure gas refrigerant circulation pipe 5 and the medium-pressure liquid refrigerant circulation pipe 4 respectively, the electric roller shutter 104 is retracted to allow air to enter, the high-pressure atomized water is closed, and the bidirectional evaporative heat exchanger 1 is used as an evaporator.

[0051] When the cold-heat storage accumulator 13 stores heat and takes out cold, the control valve component controls the two ends of the cold-heat storage accumulator 13 to be connected to the high-pressure gas refrigerant circulation pipe 3 and the medium-pressure liquid refrigerant circulation pipe 4 respectively; when storing cold and taking out heat, the control valve component controls the two ends of the cold-heat storage accumulator 13 to be connected to the low-pressure gas refrigerant circulation pipe 5 and the medium-pressure liquid refrigerant circulation pipe 4 respectively.

[0052] When the infrared radiation heat collector 14 needs to generate heat, the regulating valve on the pipeline of the infrared radiation heat collector 14 is opened, and when heating is not required, the regulating valve on the pipeline of the infrared radiation heat collector 14 is closed.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. Single-stage subcritical carbon dioxide multi-unit mixed cooling and heating balance system, characterized by: It includes a two-way evaporative 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, the suction end of the compressor is connected to the low-pressure gas refrigerant circulation pipe, and the exhaust end of the compressor is connected to the high-pressure gas refrigerant circulation pipe; the two-way evaporative heat exchanger is provided with a first port and a second port, the first port is connected to the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe respectively through a control valve component, the connection state of the first port with the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe is controlled according to the opening and closing of the control valve component, the second port is connected to the medium-pressure liquid refrigerant circulation pipe, the terminal heating component is connected to the high-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively, and the terminal refrigeration component is connected to the medium-pressure liquid refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe respectively.

2. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1 is characterized in that: The compressor, the two-way evaporative heat exchanger and the terminal of the equalizing system form a single-stage carbon dioxide circulation system, and the single-stage carbon dioxide circulation system operates below the critical point of the condensation temperature.

3. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1 is characterized in that: The terminal component that needs to switch between cooling state and heating state controls the connection state between the terminal component and the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe by opening and closing the control valve to complete the switching between cooling and heating.

4. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1 is characterized in that: A liquid reservoir is arranged between the second port of the bidirectional evaporative heat exchanger and the medium-pressure liquid refrigerant circulation pipe, and a regulating valve is arranged between the liquid reservoir and the second port.

5. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1 is characterized in that: The control valve element is a three-way control valve or two regulating valve groups respectively arranged on different pipelines.

6. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1 is characterized in that: The two-way evaporative heat exchanger includes a closed shell, a centrifugal fan, a heat exchange tube group and an atomizing nozzle. The centrifugal fan is arranged on one side of the closed shell, and the atomizing nozzle and the heat exchange tube group are arranged in the closed shell. The centrifugal fan is used to suck water vapor or air in the shell. The water vapor or air in the closed shell exchanges heat with the refrigerant flowing in the heat exchange tube group. An electric roller shutter is arranged on one side of the closed shell. The opening or closing of the electric roller shutter is used to switch the heating state or the cooling state of the heat exchanger.

7. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 6 is characterized by: A grid panel is arranged on one side of the rolling shutter.

8. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1 is characterized by: The end includes a fan coil unit that can switch between cooling and heating states. One interface of the fan coil unit is connected to a medium-pressure liquid refrigerant circulation pipe, and a regulating valve is provided on the pipeline. The other interface is connected to a high-pressure gas refrigerant circulation pipe and a low-pressure gas refrigerant circulation pipe respectively through a control valve component. The connection state of the port with the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe is controlled according to the opening and closing of the control valve component. A thermometer and a regulating valve are provided at the interface of the fan coil unit.

9. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1 is characterized by: The end includes a floor heating system for heating only, the inlet of which is connected to a high-pressure gas refrigerant circulation pipe, and the outlet is connected to a medium-pressure liquid refrigerant circulation pipe; a regulating valve is provided at the inlet of the floor heating system, and a one-way valve, a regulating valve and a thermometer are provided at the outlet.

10. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 9, characterized in that: The floor heating is a parallel multi-row pipeline set up in multiple rooms. The floor heating pipes include an air supply pipe, a liquid return pipe and several branch pipes. The branch pipes are bent outward continuously for multiple circles and coiled in the floor. The floor includes a concrete slab, a reflective layer, a wire mesh, a heat storage layer and a floor tile layer laid in sequence. The branch pipes are fixed to the wire mesh by clamps and abut against the coil layer. The reflective layer is made of aluminum foil or extruded insulation board with aluminum foil, and the heat storage layer is a mixture of pebbles, sand and cement.

11. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1 is characterized in that: The end includes a domestic hot water tank for heating only, the inlet end of the domestic hot water tank is connected to the high-pressure gas refrigerant circulation pipe, and the outlet end is connected to 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 is provided with a regulating valve and a thermometer.

12. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1, characterized in that: The end includes a cold-heat storage device capable of switching between cooling and heating states, one interface of the cold-heat storage device is connected to a medium-pressure liquid refrigerant circulation pipe, a regulating valve is provided on the pipeline, and the other interface is respectively connected to a high-pressure gas refrigerant circulation pipe and a low-pressure gas refrigerant circulation pipe through a control valve component, and the connection state of the port with the high-pressure gas refrigerant circulation pipe and the low-pressure gas refrigerant circulation pipe is controlled according to the opening and closing of the control valve component; a thermometer is provided at the interface of the cold-heat storage device.

13. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1, characterized in that: The end includes an infrared radiation collector, the inlet end of the infrared radiation collector is connected to the medium-pressure liquid refrigerant circulation pipe, a regulating valve is arranged on the pipeline, and the outlet end is connected to the low-pressure gas refrigerant circulation pipe.

14. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 1, characterized in that: The end includes a wine cabinet heat exchanger for cooling only. The inlet end of the wine cabinet heat exchanger is connected to the medium-pressure liquid refrigerant circulation pipe, a regulating valve is arranged on the pipeline, and the outlet end is connected to the low-pressure gas refrigerant circulation pipe.

15. The single-stage subcritical carbon dioxide multi-unit hybrid cooling and heating balance system according to claim 4 is characterized in that: The regulating valve is a solenoid valve or an electronic expansion valve.

16. A control method for a single-stage subcritical carbon dioxide multi-unit mixed cooling and heating balance system, characterized in that: The exhaust pressure and suction pressure of the compressor are set for the balancing system. The exhaust pressure determines the heating capacity of the balancing system, and the suction pressure determines the cooling capacity of the balancing system. The control module monitors whether the exhaust pressure and suction pressure of the compressor are within the set range; If the exhaust pressure or suction pressure of the compressor is not within the set range, first determine the heat exchange end Whether the heat exchange end or the cooling end reaches the set operating state, if not, the exhaust pressure and suction pressure of the compressor are within the set range by starting the number of heat exchange ends or the number of cooling ends; if the heat exchange end or the cooling end is in the set operating state, one or any of the two-way evaporative heat exchanger, the cold storage heat storage device, and the infrared radiation collector is controlled to be in the heating state to satisfy that the exhaust pressure of the compressor is within the set range, or the two-way evaporative heat exchanger or the cold storage heat storage device is controlled to be in the cooling state to satisfy that the suction pressure of the compressor is within the set range.

17. The control method of the single-stage subcritical carbon dioxide multi-connected hybrid cooling and heating balance system according to claim 16, characterized in that: When the two-way evaporative heat exchanger is used for cooling, the control valve is used to control the two ends of the two-way evaporative heat exchanger to be connected to the high-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively, the electric roller shutter is closed to prevent air from entering, the high-pressure atomized water is in operation, and the two-way evaporative heat exchanger is used as a flash condenser; when heating, the control valve is used to control the two ends of the two-way evaporative heat exchanger to be connected to the low-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively, the electric roller shutter is retracted to allow air to enter, the high-pressure atomized water is closed, and the two-way evaporative heat exchanger is used as an evaporator.

18. The control method of the single-stage subcritical carbon dioxide multi-connected hybrid cooling and heating balance system according to claim 16, characterized in that: When the cold-storage heat accumulator stores heat and takes out cold, the control valve is used to control the two ends of the cold-storage heat accumulator to be connected to the high-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively; when storing cold and taking out heat, the control valve is used to control the two ends of the cold-storage heat accumulator to be connected to the low-pressure gas refrigerant circulation pipe and the medium-pressure liquid refrigerant circulation pipe respectively.

19. The control method of the single-stage subcritical carbon dioxide multi-connected hybrid cooling and heating balance system according to claim 16, characterized in that: When the infrared radiation collector needs to generate heat, the regulating valve on the infrared radiation collector pipeline is opened, and when heating is not required, the regulating valve on the infrared radiation collector pipeline is closed.

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