A CO2 refrigeration and heating system

Abstract

The application discloses a CO2 refrigeration and heating system, comprising a plurality of parallelly arranged CO2 compressors, a condenser, a liquid CO2 storage tank, a heat recovery heat exchanger, an expansion valve group and a refrigeration and heating device. The compressor compresses CO2 gas, the condenser condenses and cools the CO2 gas, the liquid storage tank stores liquid refrigerant, the heat recovery heat exchanger performs supercooling treatment on the CO2, the expansion valve group throttles and expands, and the refrigeration and heating device realizes the functions of refrigeration and heating. The system further comprises a solar heat collector, which absorbs solar energy in winter to evaporate the liquid CO2, thereby improving energy utilization efficiency. By adopting the parallelly arranged CO2 compressor configuration and integrating the battery and the solar heat collector multi-element energy system, and by combining an artificial intelligence algorithm to intelligently control the heat cycle and the valve, the system can be efficiently and stably operated under cold climate, the defrosting problem can be effectively overcome, and the peak and valley utilization of energy can be realized, so that the reliability, adaptability and annual operation economy of the heating and refrigeration can be comprehensively improved.

Description

Technical Field

[0001] This invention relates to the field of refrigeration and heat pump cycle system technology, and more specifically, to a CO2 refrigeration and heating system. Background Technology

[0002] Currently, in cold northern climate regions, the demand for building heating and cooling is increasing, posing significant challenges to traditional heat pump systems. Heat pump systems that conventionally use refrigerants such as ammonia or Freon are prone to frost buildup on the evaporator coils when operating in low-temperature environments, leading to blocked airflow and a sharp decline in heat exchange efficiency. Frequent defrosting not only interrupts heating and consumes a large amount of extra energy, but can also cause compressor malfunctions such as liquid return or vacuum operation, severely impacting system reliability, heating performance, and operational economy.

[0003] Although heat pump technology using carbon dioxide (CO2, R-744) as a refrigerant has garnered attention due to its environmental friendliness and excellent performance in low-temperature conditions, conventional CO2 systems have not completely solved the defrosting problem. They also suffer from system interruptions and efficiency fluctuations during the defrosting process. Furthermore, traditional systems rely on a single energy utilization model, typically operating directly on the power grid, making it difficult to effectively utilize off-peak electricity prices. They also lack emergency power supplies to maintain critical components during extreme weather or power outages, limiting their widespread application in frigid regions.

[0004] Furthermore, existing systems lack flexibility in regulating thermodynamic cycles, resulting in underutilization of waste heat generated during summer cooling and excessive reliance on electrically driven compressors for heating in winter, leading to high operating costs. Developing a management solution that can efficiently, stably, and economically meet the year-round heating and cooling demands of cold regions while intelligently integrating multiple energy sources has become a pressing technical problem in this field. Summary of the Invention

[0005] In view of the above-mentioned technical problems in related technologies, the present invention proposes a CO2 refrigeration and heating system that can overcome the above-mentioned shortcomings of the prior art.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is implemented as follows:

[0007] A CO2 refrigeration and heating system;

[0008] The CO2 refrigeration and heating system includes several CO2 compressors, condensers, liquid CO2 storage tanks, heat recovery heat exchangers, expansion valve assemblies, and refrigeration and heating devices connected in parallel.

[0009] The CO2 compressor is used to compress CO2 refrigerant;

[0010] The condenser is connected to the outlet of the CO2 compressor and is used to condense or cool the compressed CO2.

[0011] The liquid CO2 storage tank is used to store liquid CO2;

[0012] The heat recovery heat exchanger is connected to the pipeline between the condenser and the liquid CO2 storage tank, and is used to subcool the CO2 flowing into the liquid CO2 storage tank;

[0013] The expansion valve assembly is installed on the pipeline between the condenser and the heat recovery heat exchanger, and is used to throttle and expand CO2.

[0014] The refrigeration and heating device is connected to the liquid CO2 storage tank through a heat exchanger, valves and pipelines to achieve refrigeration or heating functions.

[0015] The CO2 refrigeration and heating system also includes a solar collector connected to the liquid CO2 storage tank, used to absorb solar energy and evaporate the liquid CO2 in winter.

[0016] Furthermore, the expansion valve assembly includes a receiving tank, an automatic expansion valve, and a control valve for regulating the mass flow rate and thermodynamic state of CO2.

[0017] Furthermore, the system also includes a battery array for storing electricity during periods of low cost and powering the CO2 compressor.

[0018] Furthermore, it also includes an auxiliary battery array for providing emergency power to the liquid CO2 storage tank or system pump in extreme weather conditions or power outages.

[0019] Furthermore, the system also includes a supercritical loop connected between the condenser and the suction line of the CO2 compressor, for directly introducing high-pressure CO2 into the suction line.

[0020] Furthermore, a function exchange device is also provided on the intake pipe.

[0021] Furthermore, the system also includes an antifreeze heat exchanger that exchanges heat with a summer chilled water tank through an antifreeze circulation loop, for making ice and providing chilled water in the summer.

[0022] Furthermore, the antifreeze heat exchanger includes a coil heat exchanger, which is installed in the summer cold water tank.

[0023] Furthermore, the antifreeze heat exchanger is installed inside the liquid CO2 storage tank, and the antifreeze heat exchanger is immersed in the liquid CO2 inside the liquid CO2 storage tank. The antifreeze heat exchanger is used to prevent the circulating water from freezing.

[0024] Furthermore, the expansion valve assembly can be replaced by an injector to improve efficiency when the system is in a gas-phase surplus state or under high flow conditions.

[0025] The beneficial effects of this invention are as follows: By adopting a parallel CO2 compressor configuration and integrating a multi-energy system of storage battery and solar collector, and combining artificial intelligence algorithms to intelligently regulate the thermal cycle and valves, the system can operate efficiently and stably in cold climates, effectively overcome the defrosting problem and realize peak-shifting and valley-filling of energy utilization, thereby achieving the goal of comprehensively improving the reliability, adaptability and year-round economic efficiency of heating and cooling. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of a CO2 refrigeration and heating system according to an embodiment of the present invention;

[0028] In the diagram: 1. CO2 compressor; 2. Battery array; 3. Auxiliary battery array; 4. Condenser; 5. Winter hot water tank; 5-1. Summer cooling tower; 5-3. Hot water supply heat exchanger; 6. Summer cold water tank; 6-1. First regulating valve; 6-2. Second regulating valve; 6-3. Refrigeration and heating device; 7. Receiving tank; 8. Automatic expansion valve; 8-1. Cooling mode regulating valve; 8-2. Heating mode regulating valve; 9. Control valve ; 10. Heat recovery heat exchanger; 11. Liquid CO2 storage tank; 12. Liquid CO2 pump; 13. Antifreeze heat exchanger; 13-1. Coil heat exchanger; 14. Antifreeze pump; 15. Solar collector; 16. Third regulating valve; 17. Supercritical loop; 17-2. Functional exchange device; 20. Summer valve; 21. Winter valve; 22. Regenerator; 23. Water circulation pump; a. Circulation point; b. Suction pipeline; e. Storage tank diversion point. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0030] It should be understood that in the description of the embodiments of the present invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of the present invention and for simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of the embodiments of the present invention, "several" means two or more, unless otherwise explicitly specified.

[0031] like Figure 1 As shown, a CO2 refrigeration and heating system according to an embodiment of the present invention includes several CO2 compressors 1, condensers 4, liquid CO2 storage tanks 11, heat recovery heat exchangers 10, expansion valve groups, and refrigeration and heating devices 6-3 arranged in parallel.

[0032] The CO2 compressor 1 is used to compress CO2 refrigerant;

[0033] The condenser 4 is connected to the outlet of the CO2 compressor 1 and is used to condense or cool the compressed CO2.

[0034] The liquid CO2 storage tank 11 is used to store liquid CO2;

[0035] The heat recovery heat exchanger 10 is connected to the pipeline between the condenser 4 and the liquid CO2 storage tank 11, and is used to subcool the CO2 flowing into the liquid CO2 storage tank 11.

[0036] The expansion valve assembly is installed on the pipeline between the condenser 4 and the heat recovery heat exchanger 10, and is used to throttle and expand CO2.

[0037] The refrigeration and heating device 6-3 is connected to the liquid CO2 storage tank 11 via a heat exchanger, valves and pipelines to achieve refrigeration or heating functions.

[0038] The CO2 refrigeration and heating system also includes a solar collector 15 connected to the liquid CO2 storage tank 11, which is used to absorb solar energy and evaporate liquid CO2 in winter.

[0039] According to an embodiment of the present invention, a CO2 refrigeration and heating system is provided. In a specific embodiment, the expansion valve assembly includes a receiving tank 7, an automatic expansion valve 8, and a control valve 9, which are used to regulate the mass flow rate and thermodynamic state of CO2.

[0040] According to an embodiment of the present invention, a CO2 refrigeration and heating system further includes a battery array 2 in a specific embodiment for storing electricity during periods of low cost and supplying power to the CO2 compressor 1.

[0041] According to an embodiment of the present invention, a CO2 refrigeration and heating system further includes, in a specific embodiment, an auxiliary battery array 3 for providing emergency power to the liquid CO2 storage tank 11 or the system pump in extreme weather conditions or power outages.

[0042] According to an embodiment of the present invention, a CO2 refrigeration and heating system further includes a supercritical loop 17 in a specific embodiment. The supercritical loop 17 is connected between the condenser 4 and the suction pipe b of the CO2 compressor 1, and is used to directly introduce high-pressure CO2 into the suction pipe.

[0043] According to an embodiment of the present invention, a CO2 refrigeration and heating system is provided, in a specific embodiment, a function exchange device 17-2 is further provided on the intake pipe b.

[0044] According to an embodiment of the present invention, a CO2 refrigeration and heating system further includes an antifreeze heat exchanger 13 in a specific embodiment, which exchanges heat with a summer cold water tank 6 through an antifreeze circulation loop for making ice and providing cold water in summer.

[0045] According to an embodiment of the present invention, a CO2 refrigeration and heating system is provided. In a specific embodiment, the antifreeze heat exchanger 13 includes a coil heat exchanger 13-1, which is disposed in the summer cold water tank 6.

[0046] According to an embodiment of the present invention, a CO2 refrigeration and heating system is provided. In a specific embodiment, the antifreeze heat exchanger 13 is disposed in the liquid CO2 storage tank 11 and is immersed in the liquid CO2 in the liquid CO2 storage tank 11. The antifreeze heat exchanger 13 is used to prevent the circulating water from freezing.

[0047] According to an embodiment of the present invention, in a CO2 refrigeration and heating system, in a specific embodiment, the expansion valve assembly can be replaced by an ejector to improve efficiency when the system is in a gas phase surplus state or under high flow conditions.

[0048] To facilitate understanding of the above technical solutions of the present invention, the following detailed description of the above technical solutions of the present invention will be provided through specific usage methods.

[0049] In practical use, the CO2 refrigeration and heating system according to the present invention includes multiple CO2 compressors 1 connected in parallel. By adjusting the input frequency and the number of compressors that start and stop, the system can adapt to changes in heating and cooling loads under different climatic conditions, such as seasonal changes and weather fluctuations, thereby achieving optimal system operation in terms of economic efficiency.

[0050] The CO2 compressor 1 is powered by a battery array 2 (such as lithium iron phosphate batteries). This system can store electricity during periods of low electricity prices and use the stored energy during daily operation. In addition, the system is equipped with an auxiliary battery array 3 to provide emergency power to the liquid CO2 storage tank 11 and related pumps and control systems in extreme weather (such as temperatures as low as -25°C) or grid failures, preventing system shutdown.

[0051] Compressed supercritical or subcritical CO2 gas enters condenser 4 (or acts as a gas cooler), where it condenses or cools into a liquid phase (or a gas-liquid two-phase system). The latent heat released during condensation is transferred to the water circuit, raising the water temperature to a level suitable for heating and hot water supply. Hot water is pumped to the winter hot water tank 5 for thermal storage for nighttime use, and can also be circulated to the refrigeration and heating unit 6-3. During summer operation, the operating mode of the refrigeration and heating unit 6-3 is switched via the cooling mode regulating valve 8-1 and the heating mode regulating valve 8-2, allowing it to receive cold water from the first regulating valve 6-1 and return the water via the second regulating valve 6-2. These two regulating valves also control the temperature of the liquid CO2 storage tank 11 during winter operation to prevent it from getting too cold, thus achieving a defrost cycle. The hot water supply heat exchanger 5-3 is directly connected to the hot water circulation loop of condenser 4 to meet actual hot water demand. In summer, waste heat generated by the compressor can be discharged through the summer cooling tower 5-1 connected to the hot water circuit. In large residences or special settings, this hot water circulation can also be converted into a high-temperature liquid state, which helps to delay equipment aging and corrosion.

[0052] The condensed high-pressure CO2 liquid (or gas-liquid two-phase mixture) is divided into two paths: one is the main refrigeration cycle, flowing through receiving tank 7 to achieve gas-liquid separation, with the liquid phase entering the expansion process. This process is achieved through automatic expansion valve 8 and control valve 9. These valves can monitor the pressure and temperature of multiple nodes in the system based on artificial intelligence algorithms, dynamically adjusting the CO2 mass flow rate to keep the liquid CO2 storage tank 11 in an optimal thermal state. The other path is through supercritical loop 17, which switches between supercritical and subcritical cycles within minutes according to AI control commands, sending the high-pressure, high-temperature CO2 mixture into liquid CO2 storage tank 11, or directly into the suction line b of CO2 compressor 1. The suction line is also equipped with a functional exchange device 17-2 to stabilize the compressor's suction state.

[0053] The expanded CO2 gas-liquid two-phase mixture enters the heat recovery heat exchanger 10 through circulation point a, where it exchanges heat with the gas phase in the liquid CO2 storage tank 11, thereby subcooling the CO2 in the tank to the liquid state required for refrigeration. The liquid CO2 is then transported to the refrigeration circuit by the liquid CO2 pump 12, flowing through the antifreeze heat exchanger 13. This heat exchanger circulates brine through the antifreeze pump 14, exchanging heat with the summer cold water tank 6. By maintaining the brine temperature below the freezing point, ice can be made in the coil heat exchanger 13-1 in the summer cold water tank 6, thus providing low-temperature cold water for the refrigeration and heating device 6-3.

[0054] As an alternative structure for summer cooling, the system can also install an antifreeze heat exchanger 13 inside the liquid CO2 storage tank 11. The antifreeze heat exchanger 13 is immersed in the liquid CO2 in the liquid CO2 storage tank 11, which can prevent the circulating water from freezing.

[0055] In the refrigeration circuit following the liquid CO2 storage tank 11, the liquid CO2 is divided into two paths at the tank's branch point e, controlled by summer valve 20 and winter valve 21. During the winter daytime, the liquid CO2 flows through the solar collector 15, absorbing solar radiation when there is ample sunlight and absorbing heat from the air on cloudy or rainy days, causing the CO2 to evaporate into gas and return to the liquid CO2 storage tank 11 before entering the compressor 1. At this time, the heat recovery heat exchanger 10 stops working. Through the cooperation of the third regulating valve 16 and the seasonal valve, the pressure and temperature inside the tank can be effectively controlled, increasing the evaporation temperature and achieving high COP operation, which is especially suitable for cold northern regions.

[0056] In addition, when the CO2 gas phase content at the outlet of condenser 4 is high, or the system compressor flow rate is large, or the condenser is used as a gas cooler, the receiving tank 7, automatic expansion valve 8 and control valve 9 in the expansion process can be replaced by an ejector to improve system efficiency.

[0057] In summary, by employing the above-mentioned technical solution of the present invention, a multi-energy system integrating parallel CO2 compressors, batteries, and solar collectors is configured and integrated. Combined with artificial intelligence algorithms for intelligent control of the thermal cycle and valves, the system can operate efficiently and stably in cold climates. This effectively overcomes the difficulties of defrosting and low energy utilization of traditional heat pumps, achieving peak energy shifting and flexible switching between multiple thermal modes. Ultimately, this comprehensively improves the system's heating and cooling reliability, environmental adaptability, and year-round operational economy.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A CO2 refrigeration and heating system, characterized in that, It includes several CO2 compressors (1) connected in parallel, a condenser (4), a liquid CO2 storage tank (11), a heat recovery heat exchanger (10), an expansion valve assembly, and refrigeration and heating devices (6-3). The CO2 compressor (1) is used to compress CO2 refrigerant; The condenser (4) is connected to the outlet of the CO2 compressor (1) and is used to condense or cool the compressed CO2. The liquid CO2 storage tank (11) is used to store liquid CO2; The heat recovery heat exchanger (10) is connected to the pipeline between the condenser (4) and the liquid CO2 storage tank (11). The heat recovery heat exchanger (10) is used to exchange heat between CO2 from the condenser (4) and gaseous CO2 from the liquid CO2 storage tank (11) to subcool the CO2 flowing into the liquid CO2 storage tank (11). The expansion valve assembly is installed on the pipeline between the condenser (4) and the heat recovery heat exchanger (10) for throttling and expanding CO2; The refrigeration and heating device (6-3) is connected to the liquid CO2 storage tank (11) through an antifreeze heat exchanger (13), a liquid CO2 pump (12), an antifreeze pump (14), and corresponding valves and pipelines to form an antifreeze circulation loop for making ice and providing cold water in summer or providing heating in winter. The CO2 refrigeration and heating system also includes a solar collector (15) connected to the liquid CO2 storage tank (11) for absorbing solar energy and evaporating liquid CO2 in winter.

2. The CO2 refrigeration and heating system according to claim 1, characterized in that, The expansion valve assembly includes a receiving tank (7), an automatic expansion valve (8), and a control valve (9) for regulating the mass flow rate and thermodynamic state of CO2.

3. The CO2 refrigeration and heating system according to claim 1, characterized in that, The system also includes a battery array (2) for storing electricity during periods of low cost and powering the CO2 compressor (1).

4. A CO2 refrigeration and heating system according to claim 3, characterized in that, It also includes an auxiliary battery array (3) for providing emergency power to the liquid CO2 storage tank (11) or system pump in extreme weather conditions or power outages.

5. A CO2 refrigeration and heating system according to claim 1, characterized in that, The system also includes a supercritical loop (17), which is connected between the condenser (4) and the suction line (b) of the CO2 compressor (1) for directly introducing high-pressure CO2 into the suction line.

6. A CO2 refrigeration and heating system according to claim 5, characterized in that, A function exchange device (17-2) is also provided on the intake pipe (b).

7. A CO2 refrigeration and heating system according to claim 1, characterized in that, The system also includes an antifreeze heat exchanger (13) that exchanges heat with a summer cold water tank (6) through an antifreeze circulation loop for making ice and providing cold water in the summer.

8. A CO2 refrigeration and heating system according to claim 7, characterized in that, The antifreeze heat exchanger (13) includes a coil heat exchanger (13-1) installed in the summer cold water tank (6).

9. A CO2 refrigeration and heating system according to claim 7, characterized in that, The antifreeze heat exchanger (13) is installed inside the liquid CO2 storage tank (11) and is immersed in the liquid CO2 inside the liquid CO2 storage tank (11). The antifreeze heat exchanger (13) is used to prevent the circulating water from freezing.

10. A CO2 refrigeration and heating system according to claim 1, characterized in that, The expansion valve assembly is replaced by an injector to improve efficiency when the system is in a gas-phase surplus state or under high flow conditions.

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