Liquid-liquid transcritical compressed carbon dioxide energy storage system and operation method thereof

Abstract

The invention belongs to the technical field of energy storage, provides a liquid-liquid transcritical compressed carbon dioxide energy storage system and an operation method thereof, and adopts the technical scheme that a new energy power plant is coupled with a data center and the liquid-liquid transcritical compressed carbon dioxide energy storage system, so that different power generation loads of the new energy power plant are fully utilized; the requirements of the data center on green power consumption indexes are met, and stable supply of cold energy and power is ensured; the problem of insufficient cooling capacity caused by cooling capacity dissipation and heat exchange temperature difference of a liquid-liquid transcritical compression carbon dioxide energy storage system is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to a liquid-liquid transcritical compressed carbon dioxide energy storage system and an operation method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the continuous growth of global energy demand and the increasing awareness of environmental protection, the development of efficient and clean energy storage technology has become an important research direction in the energy field. New energy power, such as solar and wind power, has attracted widespread attention due to its renewability and environmental protection, but its intermittent and unstable nature has brought challenges to the stable operation of the power grid. At the same time, as an important infrastructure of information technology, data centers have extremely high requirements for the stability and reliability of power supply.

[0004] As a new type of energy storage technology, the liquid-liquid transcritical compressed carbon dioxide energy storage system shows great application potential due to its high energy storage density, high efficiency and environmental friendliness. The system compresses carbon dioxide to a transcritical state through a compressor to achieve high-density energy storage, and releases energy through an expander when needed and converts it into electrical energy, thereby effectively balancing the supply and demand fluctuations of renewable energy electricity and improving the stability of the power grid. The system liquefies the carbon dioxide at the inlet of the low-pressure side storage tank through a cold storage device, but the heat exchange process will cause the accumulation and dissipation of cold. To solve this problem, the method of increasing the throttling pressure drop is often used. However, this measure will greatly reduce the efficiency of the energy storage system. Summary of the invention

[0005] In order to solve at least one technical problem existing in the above-mentioned background technology, the present invention provides a liquid-liquid transcritical compressed carbon dioxide energy storage system and an operation method thereof, which combines the liquid-liquid transcritical compressed carbon dioxide energy storage system with a data center to construct an efficient energy management system, which can not only solve the intermittent and instability problems of new energy electricity; but also realize the stable supply of cooling energy and electric energy of the data center; at the same time, its efficient and clean energy storage characteristics also provide strong support for promoting the development of green and low-carbon energy.

[0006] During operation, data centers require a large amount of cold energy to ensure stable operation of equipment. By coupling energy storage and new energy power systems, when the power of new energy generation is low, a refrigeration cycle is used to cool the energy storage system and data centers. When the power generation is high, redundant new energy power is stored through the energy storage system to supply power to the data center when the new energy power fluctuates.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A first aspect of the present invention provides a liquid-liquid transcritical compressed carbon dioxide energy storage system, comprising a low-pressure liquid carbon dioxide storage device, a cold storage device, a compression cooling device, a cold water storage device, a hot water storage device, a high-pressure liquid carbon dioxide storage device, a heat recovery expansion device and a data center;

[0009] The outlet of the low-pressure liquid carbon dioxide storage device is connected to the inlet of the cold storage device, the outlet of the cold storage device is connected to the input end of the compression cooling device, the output end of the compression cooling device is connected to the inlet of the high-pressure liquid carbon dioxide storage device, the outlet of the high-pressure liquid carbon dioxide storage device is connected to the input end of the heat recovery expansion device, the output end of the heat recovery expansion device is connected to the inlet of the cold storage device, and the outlet of the cold storage device is connected to the low-pressure liquid carbon dioxide storage device;

[0010] The outlet of the cold water storage device is connected to the input end of the compression cooling device, the output end of the compression cooling device is connected to the inlet of the hot water storage device, the outlet of the hot water storage device is connected to the input end of the heat recovery expansion device, and the output end of the heat recovery expansion device is connected to the inlet of the cold water storage device;

[0011] The data center is connected to a cold storage device.

[0012] Furthermore, the system also includes a low-pressure throttle valve, the cold storage device includes a latent cold storage device and a sensible cold storage device, the outlet of the low-pressure liquid carbon dioxide storage device is connected to one end of the low-pressure throttle valve, the other end of the low-pressure throttle valve is connected to the inlet of the latent cold storage device, and the outlet of the latent cold storage device is connected to the inlet of the sensible cold storage device.

[0013] Furthermore, the system also includes a refrigeration cycle compressor, a refrigeration cycle condenser, and a refrigeration cycle throttle valve. The refrigeration cycle compressor, refrigeration cycle condenser, refrigeration cycle throttle valve and a sensible cooling regenerator are connected in sequence to form a circulation loop, and the data center is connected to the sensible cooling regenerator.

[0014] Furthermore, the phase change temperature range of the phase change cold storage medium of the latent cold storage device is within the phase change temperature range of carbon dioxide under the system pressure.

[0015] Further, the compression cooling device includes a first-stage compressor, a first-stage heat exchanger, a second-stage compressor and a second-stage heat exchanger;

[0016] The output end of the first stage compressor is connected to the input end of the first stage heat exchanger, the output end of the first stage heat exchanger is connected to the input end of the second stage compressor, and the output end of the second stage compressor is connected to the input end of the second stage heat exchanger;

[0017] The output ends of the first stage heat exchanger and the second stage heat exchanger are respectively connected to the inlet of the hot water storage device.

[0018] Furthermore, the system also includes a condenser and a high-pressure throttle valve, one end of the condenser is connected to the second-stage heat exchanger, and the other end is connected to the inlet of the high-pressure liquid carbon dioxide storage device, and the outlet of the high-pressure liquid carbon dioxide storage device is connected to the high-pressure throttle valve.

[0019] Further, the regenerative expansion device comprises a first-stage regenerator, a first-stage expander, a second-stage regenerator and a second-stage expander;

[0020] The output end of the first stage regenerator is connected to the input end of the first stage expander, the output end of the first stage expander is connected to the input end of the second stage regenerator, and the output end of the second stage regenerator is connected to the input end of the second stage expander;

[0021] The output end of the first-stage heat regenerator and the output end of the second-stage heat regenerator are respectively connected to the inlet of the cold water storage device.

[0022] The second aspect of the present invention provides an operation method of a liquid-liquid transcritical compressed carbon dioxide energy storage system, based on the liquid-liquid transcritical compressed carbon dioxide energy storage system of the first aspect, comprising the following steps:

[0023] When the power generation meets the power requirements of the data center and the energy storage system in the optimal operating range, the low-pressure liquid carbon dioxide storage device releases the low-pressure liquid carbon dioxide into the latent cooling storage device for cold storage, and then enters the compression cooling device in turn for compression and cooling; the cold water of the cold water storage device enters the first-stage heat exchanger and the second-stage heat exchanger for heat exchange, and the water after heat exchange is stored in the hot water storage device; the supercritical carbon dioxide at the outlet of the second-stage heat exchanger is condensed into high-pressure liquid carbon dioxide and stored in the high-pressure liquid carbon dioxide storage device;

[0024] When the power generation capacity is less than the power demand of the data center, the first-stage expander and the second-stage expander perform work to supply energy to the data center; the liquid carbon dioxide in the high-pressure liquid carbon dioxide storage device enters the heat recovery expansion device for heat recovery and expansion to perform work; the hot water in the hot water storage device enters the first-stage heat exchanger and the second-stage heat exchanger for heat exchange, and the cold water after heat exchange is stored in the cold water storage device; the low-pressure gaseous carbon dioxide at the outlet of the second-stage expander enters the cold storage device for cooling and liquefaction and is then stored in the low-pressure liquid carbon dioxide storage device.

[0025] Furthermore, when the generated power meets the electricity demand of the data center and there is surplus electricity, the electricity from the new energy power plant drives the refrigeration cycle compressor, and the outlet of the refrigeration cycle compressor is connected to the refrigeration cycle condenser, the refrigeration cycle throttle valve and the sensible cold storage device in sequence to form a refrigeration cycle, and the cold energy is stored in the sensible cold storage device.

[0026] Furthermore, when the data center needs cooling, the refrigerant medium is used to circulate heat between the sensible cold storage device and the data center to supply cooling energy.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention achieves full utilization of different power generation loads of the new energy power plant by coupling the new energy power plant with the data center and the liquid-liquid transcritical compressed carbon dioxide energy storage system; meets the requirements of the data center for green power consumption indicators and ensures a stable supply of cold energy and electricity; and solves the problem of insufficient cold capacity caused by cold dissipation and heat exchange temperature difference in the liquid-liquid transcritical compressed carbon dioxide energy storage system.

[0029] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 This is a structural diagram of a liquid-liquid transcritical compressed carbon dioxide energy storage system provided by an embodiment of the present invention;

[0032] Among them, 1. Low-pressure liquid carbon dioxide storage device; 2. Low-pressure tank throttle valve; 3. Latent cooling storage device; 4. Sensible cooling storage device; 5. Refrigeration cycle compressor; 6. Refrigeration cycle condenser; 7. Refrigeration cycle throttle valve; 8. New energy power plant; 9. First-stage compressor; 10. First-stage heat exchanger; 11. Second-stage compressor; 12. Second-stage heat exchanger; 13. Condenser; 14. High-pressure liquid carbon dioxide storage device; 15. High-pressure throttle valve; 16. First-stage regenerator; 17. First-stage expander; 18. Second-stage regenerator; 19. Second-stage expander; 20. Data center; 21. Hot water storage device; 22. Cold water storage device. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] In the present invention, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. Relevant scientific research or technical personnel in this field can determine the specific meanings of the above terms in the present invention according to specific circumstances, and they should not be understood as limiting the present invention.

[0037] Embodiment 1

[0038] This embodiment provides a liquid-liquid transcritical compressed carbon dioxide energy storage system, including a low-pressure liquid carbon dioxide storage device 1, a cold storage device, a compression cooling device, a cold water storage device 22, a hot water storage device 21, a high-pressure liquid carbon dioxide storage device 14, a heat recovery expansion device and a data center 20;

[0039] The outlet of the low-pressure liquid carbon dioxide storage device 1 is connected to the inlet of the cold storage device, the outlet of the cold storage device is connected to the input end of the compression cooling device, the output end of the compression cooling device is connected to the inlet of the high-pressure liquid carbon dioxide storage device 14, the outlet of the high-pressure liquid carbon dioxide storage device 14 is connected to the input end of the heat recovery expansion device, the output end of the heat recovery expansion device is connected to the inlet of the cold storage device, and the outlet of the cold storage device is connected to the low-pressure liquid carbon dioxide storage device 1;

[0040] The outlet of the cold water storage device 22 is connected to the input end of the compression cooling device, the output end of the compression cooling device is connected to the inlet of the hot water storage device 21, the outlet of the hot water storage device 21 is connected to the input end of the heat recovery expansion device, and the output end of the heat recovery expansion device is connected to the inlet of the cold water storage device 22;

[0041] The data center 20 is connected to a cold storage device.

[0042] Furthermore, the system also includes a low-pressure throttle valve 2, the cold storage device includes a latent cold storage device 3 and a sensible cold storage device 4, the outlet of the low-pressure liquid carbon dioxide storage device is connected to one end of the low-pressure throttle valve 2, the other end of the low-pressure throttle valve 2 is connected to the inlet of the latent cold storage device 3, and the outlet of the latent cold storage device 3 is connected to the inlet of the sensible cold storage device 4.

[0043] Furthermore, the system also includes a refrigeration cycle compressor 5, a refrigeration cycle condenser 6, and a refrigeration cycle throttle valve 7. The refrigeration cycle compressor 5, the refrigeration cycle condenser 6, the refrigeration cycle throttle valve 7 and the sensible cooling regenerator 4 are connected in sequence to form a circulation loop, and the data center 20 is connected to the sensible cooling regenerator 4.

[0044] Further, the compression cooling device includes a first-stage compressor 9, a first-stage heat exchanger 10, a second-stage compressor 11 and a second-stage heat exchanger 12;

[0045] The output end of the first stage compressor 9 is connected to the input end of the first stage heat exchanger 10, the output end of the first stage heat exchanger 10 is connected to the input end of the second stage compressor 11, and the output end of the second stage compressor 11 is connected to the input end of the second stage heat exchanger 12;

[0046] The output ends of the first stage heat exchanger 10 and the second stage heat exchanger 12 are respectively connected to the inlet of the hot water storage device 21 .

[0047] Furthermore, the system also includes a condenser 13 and a high-pressure throttle valve 15, one end of the condenser 13 is connected to the second-stage heat exchanger 12, and the other end is connected to the inlet of the high-pressure liquid carbon dioxide storage device 14, and the outlet of the high-pressure liquid carbon dioxide storage device 14 is connected to the high-pressure throttle valve 15.

[0048] Further, the regenerative expansion device includes a first-stage regenerator 16, a first-stage expander 17, a second-stage regenerator 18 and a second-stage expander 19;

[0049] The output end of the first stage regenerator 16 is connected to the input end of the first stage expander 17, the output end of the first stage expander 17 is connected to the input end of the second stage regenerator 18, and the output end of the second stage regenerator 18 is connected to the input end of the second stage expander 19;

[0050] The output ends of the first-stage regenerator 16 and the second-stage regenerator 18 are connected to the inlet of the cold water storage device 22 , respectively.

[0051] It should be noted that, in this embodiment, the pressure in the hot water tank 21 should ensure that at a given water temperature, the boiling point of water is higher than the actual temperature in the tank, thereby preventing the water from boiling and maintaining the water in a liquid state.

[0052] The freezing point of the refrigerant in the refrigeration cycle should be lower than the lowest temperature of the sensible cold storage device to prevent the refrigerant from solidifying.

[0053] The freezing point of the circulating working fluid in the data center 20 should be lower than the lowest temperature of the sensible cold storage device to prevent the circulating working fluid from freezing.

[0054] The phase change temperature of the phase change cold storage medium of the latent cold storage device 3 should conform to the phase change temperature range of carbon dioxide under the system pressure, so as to achieve better latent cold storage.

[0055] The specific working principle is:

[0056] The CO2 energy storage system is divided into energy storage and energy release processes;

[0057] In the energy storage stage, the first-stage compressor 9 and the second-stage compressor 11 are driven by electricity from the new energy power plant 8; the low-pressure storage tank 1 releases low-pressure liquid carbon dioxide, which is throttled and cooled by the low-pressure tank throttle valve 2 and then enters the latent cold storage device 3 and the sensible cold storage device 4 in turn for cold storage. During the cold storage process, the carbon dioxide absorbs heat and vaporizes, and then enters the first-stage compressor 9, the first-stage heat exchanger 10, the second-stage compressor 11 and the second-stage heat exchanger 12 in turn for compression and cooling; the cold water in the cold water tank 22 enters the first-stage heat exchanger 10 and the second-stage heat exchanger 12 for heat exchange, and the high-temperature water after heat exchange is stored in the hot water tank 21; the supercritical carbon dioxide at the outlet of the second-stage heat exchanger 12 is condensed into high-pressure liquid carbon dioxide by the condenser 13 and then stored in the high-pressure storage tank 14.

[0058] In the energy release stage, the first-stage expander 17 and the second-stage expander 19 perform work to supply energy to the data center; the liquid carbon dioxide in the high-pressure storage tank 14 enters the first-stage regenerator 16, the first-stage expander 17, the second-stage regenerator 18 and the second-stage expander 19 in sequence for heat recovery and expansion to perform work after throttling and pressure stabilization by the high-pressure tank throttle valve 15; the hot water in the hot water tank 21 enters the first-stage regenerator 16 and the second-stage regenerator 18 respectively for heat exchange, and the cold water after heat exchange is stored in the cold water tank 22; the low-pressure gaseous carbon dioxide at the outlet of the second-stage expander 19 enters the sensible cold storage device 4 and the latent cold storage device 3 in sequence for cooling and liquefaction, and is then stored in the low-pressure storage tank 1.

[0059] When the refrigeration cycle is running, the new energy power plant 8 drives the refrigeration cycle compressor 5 with electricity, and the outlet of the refrigeration cycle compressor 5 is connected with the refrigeration cycle condenser 6, the refrigeration cycle throttle valve 7 and the sensible cold storage device 4 in sequence to form a refrigeration cycle, and the cold energy is stored in the sensible cold storage device 4.

[0060] When the new energy power is in a stable stage, the electric energy generated by the new energy power plant 8 is directly supplied to the data center 20 .

[0061] When the data center 20 needs cooling, the refrigerant is used to circulate heat between the sensible cold storage device 4 and the data center 20 to supply cooling energy.

[0062] Embodiment 2

[0063] This embodiment provides an operation method of a liquid-liquid transcritical compressed carbon dioxide energy storage system, based on the liquid-liquid transcritical compressed carbon dioxide energy storage system described in Embodiment 1, comprising the following steps:

[0064] When the power generated by the new energy power plant 8 meets the power requirements of the data center 20 and the energy storage system in the optimal operating range, the energy storage process of the carbon dioxide energy storage system is started, and the new energy power plant 8 supplies power to the first-stage compressor 9, the second-stage compressor 11 and the data center 20, and the excess new energy power is physically stored in the high-pressure storage tank 14. In addition, the refrigeration cycle flexibly participates in power regulation under the premise of meeting the refrigeration demand.

[0065] Specifically include:

[0066] The low-pressure liquid carbon dioxide storage device 1 releases low-pressure liquid carbon dioxide into the latent cooling storage device for cold storage, and then enters the compression cooling device in sequence for compression and cooling; the cold water of the cold water storage device 22 enters the first-stage heat exchanger 10 and the second-stage heat exchanger 12 for heat exchange, and the water after heat exchange is stored in the hot water storage device 21; the supercritical carbon dioxide at the outlet of the second-stage heat exchanger 12 is condensed into high-pressure liquid carbon dioxide and then stored in the high-pressure liquid carbon dioxide storage device 14;

[0067] When the power generation is less than the power demand of the data center, the energy release process of the carbon dioxide energy storage system is started, and the first-stage expander 17, the second-stage expander 19 and the new energy power plant 8 jointly supply power to the data center 20;

[0068] Specifically include:

[0069] The first-stage expansion machine 17 and the second-stage expansion machine 19 perform work to provide energy for the data center 20; the liquid carbon dioxide in the high-pressure liquid carbon dioxide storage device 14 enters the heat recovery expansion device for heat recovery and expansion to perform work; the hot water in the hot water storage device 21 enters the first-stage heat exchanger 16 and the second-stage heat exchanger 18 respectively for heat exchange, and the cold water after heat exchange is stored in the cold water storage device 22; the low-pressure gaseous carbon dioxide at the outlet of the second-stage expansion machine 19 enters the cold storage device respectively for cooling and liquefaction and then is stored in the low-pressure liquid carbon dioxide storage device 1.

[0070] When the power generated by the new energy power plant 8 meets the power demand of the data center 20 and there is a small amount of surplus power, the refrigeration cycle compressor 5 is started, and the new energy power plant 8 supplies power to the data center 20 and the refrigeration cycle compressor 5 at the same time;

[0071] Specifically include:

[0072] The electricity from the new energy power plant drives the refrigeration cycle compressor 5, and the outlet of the refrigeration cycle compressor 5 is connected to the refrigeration cycle condenser 6, the refrigeration cycle throttle valve 7 and the sensible cold storage device 4 in sequence to form a refrigeration cycle, and the cold energy is stored in the sensible cold storage device 4.

[0073] When the data center 20 needs cooling, the refrigerant is used to circulate heat between the sensible cold storage device 4 and the data center 20 to supply cooling energy.

[0074] The pressure in the hot water tank should ensure that at a given water temperature, the boiling point of the water is higher than the actual temperature in the tank, thereby preventing the water from boiling and maintaining a liquid state. The freezing point of the circulating working fluid in the refrigeration cycle should be lower than the lowest temperature of the sensible cold storage device to prevent the refrigerant from solidifying. The freezing point of the circulating working fluid in the data center should be lower than the lowest temperature of the sensible cold storage device to prevent the circulating working fluid from solidifying. The phase change temperature of the phase change cold storage medium of the latent cold storage device should conform to the phase change temperature range of carbon dioxide under the system pressure, thereby achieving better latent cold storage.

[0075] From the above system operation strategies, it can be seen that according to the size of the power generation of the new energy power plant 8, the system is divided into three operation strategies. This method realizes the full utilization of different power generation loads of the new energy power plant. New energy (such as solar energy and wind energy) is intermittent and unstable. The energy storage system can store these unstable energy sources and stably supply them to the data center when needed, thereby improving the overall energy utilization efficiency. Since there is inevitably a heat exchange temperature difference in the cold storage device during operation, this leads to the loss of cold energy in the energy storage system, making it impossible to perfectly achieve the expected cold storage liquefaction efficiency. The solution of increasing the pressure drop of the low-pressure tank throttle valve 2 has a more significant impact on the overall efficiency of the system.

[0076] Therefore, in order to more effectively solve the problem of cooling energy loss, introducing additional cooling source input is considered a more ideal solution. The introduction of a small refrigeration system cycle not only provides an additional cooling source for the energy storage system, but also provides a stable operating environment for the data center. At the same time, the flexible operation of the small refrigeration system can further reduce the power fluctuations caused by intermittent and unstable power plants.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A liquid-liquid transcritical compressed carbon dioxide energy storage system, characterized in that: It comprises a low-pressure liquid carbon dioxide storage device (1), a cold storage device, a compression cooling device, a cold water storage device (22), a hot water storage device (21), a high-pressure liquid carbon dioxide storage device (14), a heat recovery expansion device and a data center (20); The outlet of the low-pressure liquid carbon dioxide storage device (1) is connected to the inlet of the cold storage device, the outlet of the cold storage device is connected to the input end of the compression cooling device, the output end of the compression cooling device is connected to the inlet of the high-pressure liquid carbon dioxide storage device (14), the outlet of the high-pressure liquid carbon dioxide storage device (14) is connected to the input end of the heat recovery expansion device, the output end of the heat recovery expansion device is connected to the inlet of the cold storage device, and the outlet of the cold storage device is connected to the low-pressure liquid carbon dioxide storage device (1); The outlet of the cold water storage device (22) is connected to the input end of the compression cooling device, the output end of the compression cooling device is connected to the inlet of the hot water storage device (21), the outlet of the hot water storage device (21) is connected to the input end of the heat recovery expansion device, and the output end of the heat recovery expansion device is connected to the inlet of the cold water storage device (22); The data center (20) is connected to a cold storage device.

2. A liquid-liquid transcritical compressed carbon dioxide energy storage system according to claim 1, characterized in that: The system also includes a low-pressure throttle valve (2), the cold storage device includes a latent cold storage device (3) and a sensible cold storage device (4), the outlet of the low-pressure liquid carbon dioxide storage device is connected to one end of the low-pressure throttle valve (2), the other end of the low-pressure throttle valve (2) is connected to the inlet of the latent cold storage device (3), and the outlet of the latent cold storage device (3) is connected to the inlet of the sensible cold storage device (4).

3. A liquid-liquid transcritical compressed carbon dioxide energy storage system according to claim 2, characterized in that: The system further comprises a refrigeration cycle compressor (5), a refrigeration cycle condenser (6), and a refrigeration cycle throttle valve (7); the refrigeration cycle compressor (5), the refrigeration cycle condenser (6), the refrigeration cycle throttle valve (7), and the sensible cold storage device (4) are connected in sequence to form a circulation loop; and the data center (20) is connected to the sensible cold storage device.

4. A liquid-liquid transcritical compressed carbon dioxide energy storage system according to claim 2, characterized in that: The phase change temperature range of the phase change cold storage medium of the latent cold storage device (3) is within the phase change temperature range of carbon dioxide under the system pressure.

5. The liquid-liquid transcritical compressed carbon dioxide energy storage system according to claim 1, characterized in that: The compression cooling device comprises a first-stage compressor (9), a first-stage heat exchanger (10), a second-stage compressor (11) and a second-stage heat exchanger (12); The output end of the first stage compressor (9) is connected to the input end of the first stage heat exchanger (10), the output end of the first stage heat exchanger (10) is connected to the input end of the second stage compressor (11), and the output end of the second stage compressor (11) is connected to the input end of the second stage heat exchanger (12); The output ends of the first-stage heat exchanger (10) and the second-stage heat exchanger (12) are respectively connected to the inlet of the hot water storage device (21).

6. A liquid-liquid transcritical compressed carbon dioxide energy storage system according to claim 5, characterized in that: The system further comprises a condenser (13) and a high-pressure throttle valve (15), wherein one end of the condenser (13) is connected to the second-stage heat exchanger (12), and the other end is connected to the inlet of the high-pressure liquid carbon dioxide storage device (14), and the outlet of the high-pressure liquid carbon dioxide storage device (14) is connected to the high-pressure throttle valve (15).

7. A liquid-liquid transcritical compressed carbon dioxide energy storage system according to claim 5, characterized in that: The heat recovery expansion device comprises a first-stage heat regenerator (16), a first-stage expander (17), a second-stage heat regenerator (18) and a second-stage expander (19); The output end of the first stage regenerator (16) is connected to the input end of the first stage expander (17), the output end of the first stage expander (17) is connected to the input end of the second stage regenerator (18), and the output end of the second stage regenerator 18 is connected to the input end of the second stage expander (19); The output end of the first-stage heat regenerator (16) and the output end of the second-stage heat regenerator (18) are respectively connected to the inlet of the cold water storage device (22).

8. An operating method of a liquid-liquid transcritical compressed carbon dioxide energy storage system, based on the liquid-liquid transcritical compressed carbon dioxide energy storage system according to any one of claims 1 to 7, characterized in that: The steps include: When the power generation meets the power requirements of the data center and the energy storage system in the optimal operating range, the low-pressure liquid carbon dioxide storage device (1) releases the low-pressure liquid carbon dioxide into the latent cooling storage device for cooling storage, and then enters the compression cooling device in sequence for compression and cooling; the cold water of the cold water storage device (22) enters the first-stage heat exchanger (10) and the second-stage heat exchanger (12) for heat exchange, and the water after heat exchange is stored in the hot water storage device (21); the supercritical carbon dioxide at the outlet of the second-stage heat exchanger (12) is condensed into high-pressure liquid carbon dioxide and then stored in the high-pressure liquid carbon dioxide storage device (14); When the power generation capacity is less than the power demand of the data center, the first-stage expansion machine (17) and the second-stage expansion machine (19) perform work to supply energy to the data center (20); the liquid carbon dioxide in the high-pressure liquid carbon dioxide storage device (14) enters the heat recovery expansion device for heat recovery and expansion to perform work; the hot water in the hot water storage device (21) respectively enters the first-stage heat exchanger (16) and the second-stage heat exchanger (18) for heat exchange, and the cold water after heat exchange is stored in the cold water storage device (22); the low-pressure gaseous carbon dioxide at the outlet of the second-stage expansion machine (19) respectively enters the cold storage device for cooling and liquefaction and is then stored in the low-pressure liquid carbon dioxide storage device (1).

9. The method for operating a liquid-liquid transcritical compressed carbon dioxide energy storage system according to claim 8, characterized in that: When the generated power meets the power demand of the data center and there is surplus power, the electricity of the new energy power plant drives the refrigeration cycle compressor (5), and the outlet of the refrigeration cycle compressor (5) is connected to the refrigeration cycle condenser (6), the refrigeration cycle throttle valve (7) and the sensible cold storage device (4) in sequence to form a refrigeration cycle, and the cold energy is stored in the sensible cold storage device (4).

10. The method for operating a liquid-liquid transcritical compressed carbon dioxide energy storage system according to claim 8, characterized in that: When the data center (20) needs cooling, the cooling medium is used to circulate heat in the sensible cold storage device (4) and the data center (20) to supply cooling energy.

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