Liquid carbon dioxide energy storage system and energy supply device

Abstract

The embodiment of the present application provides a liquid carbon dioxide energy storage system and energy supply equipment, and belongs to the technical field of energy storage. The system comprises: a low-pressure liquid carbon dioxide storage unit and a high-pressure liquid carbon dioxide storage unit; a vaporization and refrigeration module connected with the outlet of the low-pressure liquid carbon dioxide storage unit, configured to vaporize carbon dioxide, or configured to output cold energy by using the latent heat of phase change of carbon dioxide output by the low-pressure liquid carbon dioxide storage unit, and output the vaporized gaseous carbon dioxide; a compression heat exchange module in communication with the outlet of the vaporization and refrigeration module; a thermal management module connected with the compression heat exchange module; an expansion power generation module in communication with the high-pressure liquid carbon dioxide storage unit; and a liquefaction circulation module in communication with the outlet of the expansion power generation module and the low-pressure liquid carbon dioxide storage unit respectively. The present application can balance stable power generation and precise cooling and heating supply.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and more specifically to a liquid carbon dioxide energy storage system and energy supply equipment. Background Technology

[0002] Liquid carbon dioxide energy storage, as a highly efficient physical energy storage technology, operates on the core logic of storing and releasing energy through the liquid-to-gas phase change of CO2. Traditional systems are designed around the "storage-output" of electrical energy; during storage, electrical energy is converted into the pressure energy and heat of compression of CO2, and during release, electricity is generated through turbine expansion to meet single-energy demands such as peak shaving and emergency power supply. However, such systems have significant limitations in energy utilization. On the high-pressure side, the vaporization of liquid CO2 wastes some high-grade heat of compression, while on the low-pressure side, the vaporization of liquid CO2 consumes additional low-grade heat. These dual factors result in substantial system losses, low energy cycle efficiency, and a failure to effectively exploit the potential cold and heat energy during the phase change process.

[0003] In industrial production scenarios, industries such as ethylene production have a continuous and urgent need for low-temperature cooling energy, but often face the dilemma of insufficient cooling energy supply. At the same time, these scenarios are generally accompanied by a large amount of low-temperature waste heat of 40-50°C, which is left idle due to the lack of effective recovery methods, resulting in a supply-demand imbalance of "simultaneous shortage of cooling energy and waste of waste heat". Traditional liquid carbon dioxide energy storage systems can only output electricity and cannot achieve combined cooling, heating and power generation, making it difficult to adapt to the diverse energy needs of industrial scenarios. Even some systems that attempt to expand their functions have problems such as the inability to flexibly adjust the amount of cooling capacity and temperature level, or the conflict between the adjustment process and power generation, making it difficult to achieve both stable power generation and precise cooling and heating. Summary of the Invention

[0004] The purpose of this invention is to provide a liquid carbon dioxide energy storage system and energy supply equipment to solve the problem that existing liquid carbon dioxide energy storage systems cannot simultaneously achieve stable power generation and precise cooling and heating.

[0005] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a liquid carbon dioxide energy storage system, the system comprising: Low-pressure liquid carbon dioxide storage unit and high-pressure liquid carbon dioxide storage unit; The vaporization and refrigeration module is connected to the outlet of the low-pressure liquid carbon dioxide storage unit and is configured to vaporize carbon dioxide, or to use the latent heat of phase change of carbon dioxide output from the low-pressure liquid carbon dioxide storage unit to output cooling capacity and output the vaporized gaseous carbon dioxide. The compression heat exchange module is connected to the outlet of the vaporization and refrigeration module and is configured to compress the gaseous carbon dioxide output by the vaporization and refrigeration module, recover the heat generated during the compression process and store it in the thermal management module, and condense the compressed high-pressure gaseous carbon dioxide into high-pressure liquid carbon dioxide and send it into the high-pressure liquid carbon dioxide storage unit. A thermal management module, connected to the compression heat exchange module, is configured to output heat externally using stored compression heat. An expansion power generation module, connected to the high-pressure liquid carbon dioxide storage unit, is configured to pressurize the high-pressure liquid carbon dioxide and vaporize it using an external heat source and the heat stored in the thermal management module, and then use the vaporized high-temperature and high-pressure carbon dioxide to expand and generate electricity. The liquefaction circulation module is connected to the outlet of the expansion power generation module and the low-pressure liquid carbon dioxide storage unit, respectively, and is configured to liquefy the gaseous carbon dioxide after expansion power generation and send it back to the low-pressure liquid carbon dioxide storage unit.

[0006] Optionally, the vaporization and refrigeration module includes a vaporization branch and a refrigeration branch connected in parallel; The vaporization branch is equipped with a first evaporator, and the vaporization branch is configured to absorb external low-temperature waste heat through the first evaporator to vaporize liquid carbon dioxide. The refrigeration branch is equipped with a first heat exchanger, and the refrigeration branch is configured to output cooling capacity to the outside by utilizing the latent heat of phase change of liquid carbon dioxide through the first heat exchanger.

[0007] Optionally, the refrigeration branch is provided with an adjustable flow valve connected to the first heat exchanger, configured to control the temperature level of the cooling capacity generated by the liquid carbon dioxide by adjusting the throttling pressure of the liquid carbon dioxide.

[0008] Optionally, the system further includes a distributor, the inlet of which is connected to the low-pressure liquid carbon dioxide storage unit, and the outlet of which is connected to the vaporization branch and the refrigeration branch, respectively.

[0009] Optionally, the distributor is configured to distribute all the liquid carbon dioxide from the low-pressure liquid carbon dioxide storage unit to the vaporization branch, all to the refrigeration branch, or to the vaporization branch and the refrigeration branch in any proportion.

[0010] Optionally, the compression heat exchange module includes: The compression heat exchange submodule is configured to compress gaseous carbon dioxide, and cool the gaseous carbon dioxide and recover the heat of compression during the compression process. The first condenser, connected to the compression heat exchange submodule, is configured to condense the compressed high-pressure gaseous carbon dioxide into liquid carbon dioxide and send it into the high-pressure liquid carbon dioxide storage unit.

[0011] Optionally, the compression heat exchange submodule includes a first compression unit and a second compression unit; The inlet of the first compression unit is connected to the outlet of the refrigeration branch in the vaporization and refrigeration module, and is configured to compress and exchange heat for gaseous carbon dioxide in the refrigeration branch. The inlet of the second compression unit is connected to the first compression unit and the outlet of the vaporization branch in the vaporization and refrigeration module, respectively, and is configured to perform compression heat exchange on the gaseous carbon dioxide compressed by the first compression unit and the gaseous carbon dioxide in the vaporization branch.

[0012] Optionally, the first compression unit includes a first compressor and a second heat exchanger that are interconnected, and the second compression unit includes a second compressor and a third heat exchanger that are interconnected. The inlet of the first compressor is connected to the outlet of the refrigeration branch, the outlet of the second heat exchanger is connected to the inlet of the second compressor, and the outlet of the third heat exchanger is connected to the inlet of the first condenser.

[0013] Optionally, the thermal management module further includes a heat storage device and a cold storage device; The cold storage unit is configured to provide a cooling medium to the compression heat exchange submodule in the compression heat exchange module; The heat storage device is configured to store the compression heat recovered from the compression heat exchange module and to provide heat to the expansion power generation module and the thermal management module.

[0014] Optionally, the thermal management module further includes a heating submodule, the inlet of which is connected to the outlet of the heat storage unit, and the outlet of which is connected to the cold storage unit; the inlet b of the heating submodule is configured to connect to an external fluid to be heated. The heating submodule is configured to use the heat medium provided by the heat storage device to heat the external fluid to be heated, so as to output heat to the outside.

[0015] Optionally, the expansion power generation module includes the following components connected in sequence: A hydraulic pump, the inlet of which is connected to the high-pressure liquid carbon dioxide storage unit, is configured to pressurize the liquid carbon dioxide in the high-pressure liquid carbon dioxide storage unit; The second evaporator, connected to the outlet of the hydraulic pump, is configured to absorb heat from an external heat source and vaporize pressurized liquid carbon dioxide. The fourth heat exchanger, connected to the outlet of the second evaporator, is configured to reheat gaseous carbon dioxide using heat from the thermal management module; The turbine is connected to the outlet of the fourth heat exchanger and is used to generate electricity by expanding heated gaseous carbon dioxide.

[0016] Optionally, the liquefaction circulation module includes: The second condenser is configured to condense gaseous carbon dioxide into liquid; A throttling unit, connected to the outlet of the second condenser, is used to throttle and reduce the pressure of liquid carbon dioxide; A gas-liquid separation unit is connected to the outlet of the throttling unit, and the liquid phase outlet of the gas-liquid separation unit is connected to the low-pressure liquid carbon dioxide storage unit. The gas-liquid separation unit is configured to send depressurized gas-liquid two-phase carbon dioxide into the low-pressure liquid carbon dioxide storage unit.

[0017] Optionally, the liquefaction circulation module further includes an auxiliary compressor; The inlet of the auxiliary compressor is connected to the gas phase outlet of the gas-liquid separation unit, and the outlet is connected to the inlet pipe of the second condenser.

[0018] Optionally, the external heat source is industrial low-temperature waste heat.

[0019] Secondly, embodiments of the present invention provide an energy supply device, the device comprising the liquid carbon dioxide energy storage system described in any one of the first aspects.

[0020] In the liquid carbon dioxide energy storage system of this application, the vaporization and refrigeration module can directly supply cooling externally using the latent heat of phase change of liquid carbon dioxide, converting the unused cold energy in traditional systems into adjustable cooling products, directly alleviating the cold energy shortage in industrial scenarios. Simultaneously, the compression heat exchange module, in collaboration with the thermal management module, recovers, stores, and supplies high-grade waste heat generated during the compression process, achieving self-circulation of high-grade waste heat within the system. The expansion power generation module introduces external low-temperature industrial waste heat as one of the driving heat sources, working together with the stored compression heat to convert traditionally idle low-grade industrial waste heat into power generation, effectively utilizing low-grade waste heat. Ultimately, through the cooperation of each module, the system converts all previously discarded low-temperature waste heat and process waste heat into higher-value cold, heat, and electricity outputs without relying on additional energy consumption. This resolves the contradiction between the single function of traditional systems and the diverse energy needs of industrial scenarios, achieving cascaded energy utilization and combined cooling, heating, and power (CCHP).

[0021] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 The schematic diagram illustrates a structural schematic of a liquid carbon dioxide energy storage system according to an embodiment of this application; Figure 2 The diagram schematically illustrates a comparison of the output power of a liquid carbon dioxide energy storage system according to an embodiment of this application with that of an existing combined cooling, heating and power (CCHP) system of different capacity types.

[0023] Explanation of reference numerals in the attached figures 1. Low-pressure liquid storage tank; 2. Diverter; 3. First throttle valve; 4. First evaporator; 5. First mixer; 6. Adjustable flow valve; 7. First gas-liquid separator; 8. First heat exchanger; 9. Second mixer; 10. First compressor; 11. Second heat exchanger; 12. Second compressor; 13. Third heat exchanger; 14. First condenser; 15. High-pressure liquid storage tank; 16. Hydraulic pump; 17. Second evaporator; 18. Fourth heat exchanger; 19. Turbine; 20. Third mixer; 21. Second condenser; 22. Second throttle valve; 23. Second gas-liquid separator; 24. Auxiliary compressor; 25. Cold water tank; 26. Fourth mixer; 27. Hot water tank; 28. Fifth heat exchanger; 29. ​​Third throttle valve; 30. Fifth mixer; 31. Fourth throttle valve. Detailed Implementation

[0024] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0025] Figure 1 A schematic diagram of a liquid carbon dioxide energy storage system according to an embodiment of this application is shown. Figure 1 As shown in the figure, this application provides a liquid carbon dioxide energy storage system, which includes: The system includes a low-pressure liquid carbon dioxide storage unit 1 and a high-pressure liquid carbon dioxide storage unit 15; a vaporization and refrigeration module connected to the outlet of the low-pressure liquid carbon dioxide storage unit 1, configured to vaporize carbon dioxide or utilize the latent heat of phase change of the carbon dioxide output from the low-pressure liquid carbon dioxide storage unit 1 to output cooling capacity, and output the vaporized gaseous carbon dioxide; and a compression heat exchange module connected to the outlet of the vaporization and refrigeration module, configured to compress the gaseous carbon dioxide output from the vaporization and refrigeration module, recover the heat generated during the compression process and store it in the thermal management module, and condense the compressed high-pressure gaseous carbon dioxide into high-pressure liquid carbon dioxide before sending it to the heat management module. The high-pressure liquid carbon dioxide storage unit 15 is connected to the compression heat exchange module and is configured to output heat externally using the stored compression heat. The expansion power generation module is connected to the high-pressure liquid carbon dioxide storage unit 15 and is configured to pressurize the high-pressure liquid carbon dioxide and vaporize it using an external heat source and the heat stored in the thermal management module, and use the vaporized high-temperature and high-pressure carbon dioxide to expand and generate electricity. The liquefaction circulation module is connected to the outlet of the expansion power generation module and the low-pressure liquid carbon dioxide storage unit 1, and is configured to liquefy the gaseous carbon dioxide after expansion power generation and send it back to the low-pressure liquid carbon dioxide storage unit 1.

[0026] In this embodiment, the vaporization and cooling module is connected to the outlet of the low-pressure liquid carbon dioxide storage unit 1 and mainly undertakes two functions: first, it uses the latent heat of phase change of liquid carbon dioxide to output cooling capacity to the outside, that is, the large amount of heat absorbed by liquid carbon dioxide when it vaporizes under specific conditions is used to cool the external fluid, thereby outputting the cooling capacity as a product; second, it absorbs industrial waste heat to vaporize carbon dioxide and outputs the vaporized gaseous carbon dioxide to the next module.

[0027] The compression heat exchange module is the energy storage and heat recovery end of the system. It is connected to the outlet of the vaporization and refrigeration module and receives gaseous carbon dioxide from the previous stage. The functions of this module include: compressing the gaseous carbon dioxide to increase its pressure and temperature; recovering the heat generated during compression by exchanging heat with the cooling medium and storing this recovered heat in the thermal management module; and finally, condensing the compressed high-pressure gaseous carbon dioxide into high-pressure liquid carbon dioxide and storing it in the high-pressure liquid carbon dioxide storage unit 15.

[0028] The thermal management module is the system's thermal energy management and distribution center. Connected to the compression heat exchange module, its core function is to utilize stored compression heat to output heat externally. It receives and temporarily stores high-grade compression heat from the compression heat exchange module.

[0029] The expansion power generation module is connected to the high-pressure liquid carbon dioxide storage unit 15. Its working process is as follows: first, the high-pressure liquid carbon dioxide is pressurized; then, it is vaporized and heated using an external heat source and heat stored from the thermal management module, so that it is converted into high-temperature and high-pressure gaseous carbon dioxide; finally, the high-temperature and high-pressure carbon dioxide is used to drive an expander (such as a turbine 19) to expand and generate electricity.

[0030] The liquefaction circulation module is connected to the outlet of the expansion power generation module and the low-pressure liquid carbon dioxide storage unit 1. Its core function is to reliquefy the low-pressure gaseous carbon dioxide after expansion power generation and send it back to the low-pressure liquid carbon dioxide storage unit 1, thereby forming a complete and closed circulation loop.

[0031] The overall workflow of the liquid carbon dioxide energy storage system is as follows: During the energy storage phase, liquid carbon dioxide flows out from the low-pressure storage tank, is supplied to the outside via the refrigeration branch in the vaporization and refrigeration module, and is vaporized via the vaporization branch. It is then compressed and condensed by the compression heat exchange module and stored in the high-pressure storage tank, while the heat of compression is recovered to the thermal management module. During the energy release phase, liquid carbon dioxide flows out from the high-pressure storage tank, is pressurized and heated by the expansion power generation module, and expands to generate electricity, becoming low-pressure gaseous carbon dioxide. Finally, it is liquefied by the liquefaction cycle module and returned to the low-pressure storage tank, completing the cycle.

[0032] In this embodiment, the refrigeration branch in the vaporization and refrigeration module can directly supply cooling externally using the latent heat of phase change of liquid carbon dioxide, converting unused cold energy in traditional systems into adjustable cooling products, directly alleviating the cold energy shortage in industrial scenarios. Simultaneously, the compression heat exchange module, in collaboration with the thermal management module, recovers, stores, and supplies high-grade waste heat generated during the compression process, achieving self-circulation of high-grade waste heat within the system. The expansion power generation module introduces external low-temperature industrial waste heat as one of the driving heat sources, working in conjunction with the stored compression heat to convert traditionally idle low-grade industrial waste heat into power generation, effectively utilizing low-grade waste heat. Ultimately, through the cooperation of each module, the system converts all previously discarded low-temperature waste heat and process waste heat into higher-value cold, heat, and electricity outputs without relying on additional energy consumption. This resolves the contradiction between the single function of traditional systems and the diverse energy demands of industrial scenarios, achieving cascaded energy utilization and combined cooling, heating, and power (CCHP).

[0033] In one embodiment of this application, the vaporization and refrigeration module includes a vaporization branch and a refrigeration branch connected in parallel; The vaporization branch is equipped with a first evaporator 4, and the vaporization branch is configured to absorb external low-temperature waste heat through the first evaporator 4 to vaporize liquid carbon dioxide. The refrigeration branch is equipped with a first heat exchanger 8, and the refrigeration branch is configured to output cooling capacity to the outside by utilizing the latent heat of phase change of liquid carbon dioxide through the first heat exchanger 8.

[0034] In this embodiment, as shown in the appendix Figure 1 As shown, the vaporization and refrigeration module consists of two parallel branches: Vaporization Branch: The core component of this branch is the first evaporator 4. Its inlet is connected to the outlet of the distributor 2 via the first throttle valve 3, and its outlet is connected to the subsequent compression module. This branch constitutes the path for the basic vaporization and waste heat utilization of liquid carbon dioxide. The working process of the vaporization branch is as follows: liquid carbon dioxide from the distributor 2 is depressurized by the first throttle valve 3 and enters the first evaporator 4. In the evaporator, the liquid carbon dioxide absorbs low-temperature industrial waste heat (e.g., 40-50°C) from the outside, completing the phase change from liquid to gas, providing gaseous carbon dioxide for the subsequent compression process.

[0035] Refrigeration Branch: The core component of this branch is the first heat exchanger 8. Its inlet a is connected to the other outlet b of the distributor 2 via an adjustable flow valve 6 and a first gas-liquid separator 7. The outlet b of the first heat exchanger 8 is connected to the subsequent compression module via a second mixer 9. The working process of the refrigeration branch is as follows: Liquid carbon dioxide from the distributor 2 is depressurized by the adjustable flow valve 6, becoming a low-temperature gas-liquid two-phase flow, which enters the first gas-liquid separator 7 for separation. The separated saturated liquid carbon dioxide enters the first heat exchanger 8, where it exchanges heat with the external fluid to be cooled. The external cooling liquid is input into the inlet c of the first heat exchanger 8 through the fourth throttle valve, thus entering the first heat exchanger 8. The liquid carbon dioxide absorbs heat from the fluid and completely vaporizes, thereby carrying away heat and outputting cooling capacity, while the fluid flows out through the outlet d of the first heat exchanger 8. The core of this process is to utilize the characteristic of carbon dioxide absorbing a large amount of latent heat of phase change during vaporization, directly outputting cooling capacity as a product.

[0036] In this embodiment, the vaporization function required for the cycle and the user-oriented refrigeration function are separated in the physical flow path, allowing them to operate and be controlled independently without interference. This effectively taps into and converts unused cold energy from traditional energy storage processes into valuable products, while the vaporization branch effectively utilizes industrial waste heat, jointly improving the overall energy utilization efficiency and economy of the entire system.

[0037] In one embodiment of this application, an adjustable flow valve 6 connected to the first heat exchanger 8 is provided on the refrigeration branch, configured to control the temperature level of the cooling capacity generated by the liquid carbon dioxide by adjusting the throttling pressure of the liquid carbon dioxide.

[0038] In this embodiment, as shown in the appendix Figure 1As shown, the adjustable flow valve 6 is installed on the refrigeration branch. Its inlet is connected to the corresponding outlet of the distributor 2 via a pipeline, and its outlet is connected to the inlet of the first gas-liquid separator 7. The liquid phase outlet of the first gas-liquid separator 7 is then connected to the first heat exchanger 8. Therefore, all liquid carbon dioxide distributed from the distributor 2 to the refrigeration branch must first flow through this adjustable flow valve 6.

[0039] Throttling and pressure reduction refers to the adjustment of the valve opening when liquid carbon dioxide flows through the adjustable flow valve 6, thereby generating a controllable local resistance to the fluid, resulting in a reduction in the carbon dioxide pressure in the downstream pipeline.

[0040] After being throttled and depressurized, the carbon dioxide becomes a low-temperature, low-pressure gas-liquid two-phase mixture. Its saturation temperature is determined by this pressure. Therefore, by precisely adjusting the opening of the adjustable flow valve 6, a specific evaporation pressure can be set, thereby indirectly setting the temperature at which carbon dioxide evaporates in the first heat exchanger 8. The evaporation temperature directly determines the low-temperature level that the first heat exchanger 8 can achieve, i.e., the temperature level of the output cooling capacity.

[0041] In this embodiment, the required low-temperature cooling capacity can be produced by adjusting the valve opening according to the specific needs of the external industrial process.

[0042] In one embodiment of this application, the system further includes a distributor 2, the inlet of which is connected to the low-pressure liquid carbon dioxide storage unit 1, and the outlet of which is connected to the vaporization branch and the refrigeration branch, respectively.

[0043] In one embodiment, the distributor 2 is configured to distribute all the liquid carbon dioxide from the low-pressure liquid carbon dioxide storage unit 1 to the vaporization branch, all to the refrigeration branch, or in any proportion to both the vaporization branch and the refrigeration branch.

[0044] In this embodiment, as Figure 1 As shown, the inlet of the distributor 2 is directly connected to the outlet of the low-pressure liquid carbon dioxide storage unit 1 via a pipeline, receiving liquid carbon dioxide from the storage tank. The distributor 2 has two outlets, which are connected to the inlets of the vaporization branch and the refrigeration branch via independent pipelines, respectively. Specifically, one outlet is connected to the first throttle valve 3 in the vaporization branch, and the other outlet is connected to the adjustable flow valve 6 in the refrigeration branch.

[0045] The function of the distributor 2 is to distribute the flow of liquid carbon dioxide. It divides the single stream of liquid carbon dioxide from the low-pressure storage tank into two independent branches according to the system's operational requirements, and then distributes them to the parallel-connected vaporization branch and refrigeration branch, respectively. The distribution process can allocate all the liquid carbon dioxide to the vaporization branch, all the liquid carbon dioxide to the refrigeration branch, or any proportion of the liquid carbon dioxide to both branches.

[0046] In this embodiment, a diverter 2 is used to divert the low-pressure liquid carbon dioxide to adjust the amount of cooling generated by the vaporization of liquid carbon dioxide.

[0047] In one embodiment of this application, the compression heat exchange module includes: The compression heat exchange submodule is configured to compress gaseous carbon dioxide, and cool the gaseous carbon dioxide and recover the heat of compression during the compression process. The first condenser 14, connected to the compression heat exchange submodule, is configured to condense the compressed high-pressure gaseous carbon dioxide into liquid carbon dioxide and send it into the high-pressure liquid carbon dioxide storage unit 15.

[0048] In this embodiment, the compression heat exchange submodule is used for compression and heat recovery functions. In a specific implementation, it may include a multi-stage compressor and interstage heat exchangers connected to the outlets of each compressor stage. Specifically, it is used to compress gaseous carbon dioxide supplied from the vaporization and refrigeration module, gradually increasing its pressure from a low-pressure state to the required high-pressure state. After each stage of compression, the high-temperature, high-pressure gaseous carbon dioxide enters the corresponding interstage heat exchanger. In these heat exchangers, the high-temperature carbon dioxide exchanges heat with a cooling medium (such as chilled water) from the thermal management module, thereby achieving cooling. As a result of this heat exchange process, the carbon dioxide gas is cooled, while the cooling medium is heated, and a large amount of high-grade heat generated during compression is recovered and subsequently transported to the thermal management module for storage.

[0049] The inlet of the first condenser 14 is connected to the final outlet of the compression heat exchange submodule, and its outlet is connected to the high-pressure liquid carbon dioxide storage unit 15. The high-pressure gaseous carbon dioxide, after final compression and cooling, then enters the first condenser 14. Here, the gaseous carbon dioxide exchanges heat with the cooling medium, releasing its latent heat of liquefaction, and thus condenses into high-pressure liquid carbon dioxide. The liquefied carbon dioxide, due to its significantly reduced volume, is then stored in the high-pressure liquid carbon dioxide storage unit 15, thus completing the entire energy storage process.

[0050] In this embodiment, the high-grade heat generated during the compression process is recovered through a multi-stage compression heat exchange process, which can improve the energy utilization efficiency of the system.

[0051] In one embodiment of this application, the compression heat exchange submodule includes a first compression unit and a second compression unit; The inlet of the first compression unit is connected to the outlet of the refrigeration branch in the vaporization and refrigeration module, and is configured to compress and exchange heat for gaseous carbon dioxide in the refrigeration branch. The inlet of the second compression unit is connected to the first compression unit and the outlet of the vaporization branch in the vaporization and refrigeration module, respectively, and is configured to perform compression heat exchange on the gaseous carbon dioxide compressed by the first compression unit and the gaseous carbon dioxide in the vaporization branch.

[0052] In this embodiment, the first compression unit is configured specifically to process gaseous carbon dioxide from the refrigeration branch. Its inlet is directly connected via a pipeline to the outlet of the refrigeration branch in the vaporization and refrigeration module (i.e., the outlet of the second mixer 9). The carbon dioxide from the refrigeration branch typically has a low temperature and pressure due to the phase change process involving external refrigeration. The first compression unit first performs preliminary compression and interstage cooling on this low-temperature, low-pressure gas to increase its pressure and temperature, and recovers this portion of the heat of compression.

[0053] The second compression unit is configured to process a mixture of gaseous carbon dioxide from two sources. Its inlet is connected to two sources via pipes: one is the outlet of the first compression unit, used to receive the carbon dioxide after initial compression by the first compression unit; the other is the outlet of the vaporization branch in the vaporization and refrigeration module (i.e., the outlet of the first evaporator 4), used to receive uncompressed gaseous carbon dioxide from this branch. These two gas streams are mixed before entering the second compression unit. By mixing these two gas streams with different states, the gas entering the second compression unit can have a more suitable initial temperature and pressure, which helps optimize the efficiency of the second-stage compression process and reduce overall compression power consumption. The second compression unit then performs final compression and heat exchange on this mixture, raising it to the high-pressure state required by the first condenser 14 and completing the final recovery of compression heat.

[0054] In this embodiment, different compression units can be used to process the intake air under different conditions, avoiding the efficiency loss caused by mixing low-temperature and low-pressure gas with high-temperature gas and compressing them together, so that each compression stage can operate under better conditions.

[0055] In one embodiment of this application, the first compression unit includes a first compressor 10 and a second heat exchanger 11 that are interconnected, and the second compression unit includes a second compressor 12 and a third heat exchanger 13 that are interconnected. The inlet of the first compressor 10 is connected to the outlet of the refrigeration branch, the outlet of the second heat exchanger 11 is connected to the inlet of the second compressor 12, and the outlet of the third heat exchanger 13 is connected to the inlet of the first condenser 14. It should be noted that a first mixer 5 is also provided between the second heat exchanger 11 and the second compressor 12, for mixing the carbon dioxide entering the second heat exchanger 11 and the vaporization branch before feeding it into the second compressor 12.

[0056] In this embodiment, the first compression unit includes a first compressor 10 and a second heat exchanger 11. The inlet of the first compressor 10 is connected to the outlet of the refrigeration branch (i.e., the outlet of the second mixer 9), receiving all gaseous carbon dioxide from the refrigeration branch. The inlet of the second heat exchanger 11 is connected to the outlet of the first compressor 10, receiving the high-temperature carbon dioxide after the first stage compression. The outlet of the second heat exchanger 11 is connected to the inlet of the second compressor 12, conveying the cooled carbon dioxide to the next stage.

[0057] Specifically, low-pressure carbon dioxide gas from the refrigeration branch first enters the first compressor 10, where it is compressed, resulting in a significant increase in pressure and temperature. Subsequently, the high-temperature gas enters the second heat exchanger 11, where it exchanges heat with a cooling medium (such as chilled water) from the thermal management module. The gas is cooled, and the heat from the first stage of compression it carries is recovered to the thermal management module. The cooled gas pressure remains essentially unchanged, but its temperature has dropped to near the temperature of the cooling medium, creating favorable intake conditions for the second stage of compression.

[0058] The second compression unit includes a second compressor 12 and a third heat exchanger 13. The inlet of the second compressor 12 is connected to the outlet of the second heat exchanger 11 and the outlet of the vaporization branch (i.e., the outlet of the first evaporator 44), receiving gas mixtures from both. The inlet of the third heat exchanger 13 is connected to the outlet of the second compressor 12, receiving the high-temperature, high-pressure carbon dioxide after final compression. The outlet of the third heat exchanger 13 is connected to the inlet of the first condenser 14, delivering the carbon dioxide, which has completed the entire compression and cooling process, to the condensation unit.

[0059] Specifically, the cooled carbon dioxide exiting the second heat exchanger 11 mixes with uncompressed gaseous carbon dioxide from the vaporization branch, and together they enter the second compressor 12 for final compression, reaching the system's maximum set pressure. Subsequently, this high-temperature, high-pressure gas enters the third heat exchanger 13, where it again exchanges heat with the cooling medium, recovering the heat of the second-stage compression, and the gas itself is cooled to near room temperature. Finally, this high-pressure, room-temperature gaseous carbon dioxide is sent to the first condenser 14 for liquefaction.

[0060] In this embodiment, by using multiple compressors and heat exchangers, it can be ensured that the high-grade heat generated by each stage of compression can be recovered in a timely and independent manner, thereby maximizing energy utilization efficiency.

[0061] In one embodiment of this application, the thermal management module further includes a heat storage device and a cold storage device; The cold storage unit is configured to provide a cooling medium to the compression heat exchange submodule in the compression heat exchange module; The heat storage device is configured to store the compressed heat recovered from the compression heat exchange module and to provide a heat source to the expansion power generation module and the thermal management module.

[0062] In this embodiment, the cold storage unit can specifically be a cold water tank 25. It is used to provide cooling medium to the compression heat exchange submodule in the compression heat exchange module. Specifically, it supplies cooling water to the second heat exchanger 11, the third heat exchanger 13, and the first condenser 14.

[0063] Specifically, the cooling medium in the cold storage tank is pumped to each heat exchanger in the compression heat exchange module. In the second heat exchanger 11 and the third heat exchanger 13, the cold water absorbs the heat of compression and becomes hot water. The hot water from the second heat exchanger 11 and the third heat exchanger 13 is mixed by the fourth mixer 26, which is connected to both the second heat exchanger 11 and the third heat exchanger 13, and then flows into the heat storage tank. In the first condenser 14, the cold water is used to condense high-pressure gaseous carbon dioxide, and after its temperature rises, it also flows back to the heat storage tank.

[0064] The thermal storage device can specifically be a hot water tank 27. It is used to store the compressed heat recovered from the compression heat exchange module. At the same time, it serves as a heat source, providing heat to the expansion power generation module and the thermal management module itself.

[0065] Specifically, the heat storage unit collects and stores all the compressed heat from the compression heat exchange module. During system operation, it distributes the stored heat to the expansion power generation module as needed, provides a heat source for the fourth heat exchanger 18 to heat the carbon dioxide about to enter the turbine 19, and provides a heat source for the heating submodule for external heating.

[0066] In this embodiment, the heat generated during energy storage is temporarily stored by a heat storage device and a cold storage device, and then utilized during the energy release process. This solves the contradiction of the mismatch between energy generation and use in time, and ensures the stability and flexibility of the system operation.

[0067] In one embodiment of this application, the thermal management module further includes a heating submodule, the inlet of which is connected to the outlet of the heat storage device, and the outlet of which is connected to the cold storage device; the inlet of the heating submodule is configured to connect to an external fluid to be heated. The heating submodule is configured to use the heat medium provided by the heat storage device to heat the external fluid to be heated, so as to output heat to the outside.

[0068] In this embodiment, as shown in the appendix Figure 1 As shown, the heating submodule can be the fifth heat exchanger 28 and its related piping. The specific connection relationships are as follows: The inlet of the heating submodule is connected to the outlet of the heat storage tank. Specifically, the hot-side inlet d of the fifth heat exchanger 28 is connected to the outlet of the hot water tank 27 via a pipeline to obtain the stored compression heat as a heat source. The outlet c of the heating submodule is connected to the inlet of the cold storage tank. Specifically, the hot-side outlet c of the fifth heat exchanger 28 is connected to the inlet of the cold water tank 25 via a pipeline (i.e., via the fifth mixer 30) to complete the return and circulation of the heat medium. The cold-side inlet b of the heating submodule is configured to connect to the external fluid to be heated. The external fluid to be heated enters the heating submodule through the third throttle valve 29, and after heating, flows out through the other outlet a of the fifth heat exchanger 28. Specifically, the cold-side inlet b and outlet a of the fifth heat exchanger 28 are connected to the external heating network or process equipment to form an external heating loop.

[0069] Specifically, the high-temperature heat transfer medium from the heat storage tank flows into the hot side of the fifth heat exchanger 28. Inside the heat exchanger, the heat transfer medium transfers heat to a lower-temperature external fluid to be heated (e.g., circulating water in a heating system or preheating fluid required for a process) flowing in from the other side. Through this heat exchange process, the temperature of the external fluid to be heated is increased, achieving the purpose of outputting heat. After releasing heat, the temperature of the heat transfer medium itself decreases, becoming low-temperature water. This low-temperature water flows out from the hot-side outlet of the fifth heat exchanger 28 and eventually returns to the cold storage tank.

[0070] In this embodiment, the recovered compressed heat is converted into heat energy for external output through the heating submodule, enabling the system to achieve the combined production of three energy products: "cold, heat, and electricity", thereby improving the overall energy utilization efficiency and economy of the system.

[0071] In one embodiment of this application, the expansion power generation module includes the following components connected in sequence: A hydraulic pump 16, the inlet of which is connected to the high-pressure liquid carbon dioxide storage unit 15, is configured to pressurize the liquid carbon dioxide in the high-pressure liquid carbon dioxide storage unit 15. The second evaporator 17, connected to the outlet of the hydraulic pump 16, is configured to absorb heat from an external heat source to heat the pressurized liquid carbon dioxide. The fourth heat exchanger 18, connected to the outlet of the second evaporator 17, is configured to reheat liquid carbon dioxide using heat from the thermal management module. Turbine 19 is connected to the outlet of the fourth heat exchanger 18 and is used to generate electricity by expanding heated gaseous carbon dioxide.

[0072] In this embodiment, as shown in the appendix Figure 1 As shown, the components of the expansion power generation module are connected in series according to the energy conversion sequence, wherein: The inlet of the hydraulic pump 16 is connected to the outlet of the high-pressure liquid carbon dioxide storage unit 15 via a pipeline. The inlet of the second evaporator 17 is connected to the outlet of the hydraulic pump 16. The inlet of the fourth heat exchanger 18 is connected to the outlet of the second evaporator 17. The inlet of the turbine 19 is connected to the outlet of the fourth heat exchanger 18, and is used to convert the energy of the fluid into mechanical work, thereby driving the generator to generate electricity.

[0073] Specifically, the overall workflow of the expansion power generation module is as follows: Hydraulic pump 16 pressurizes liquid carbon dioxide from the high-pressure storage tank. Then, the high-pressure liquid carbon dioxide from hydraulic pump 16 enters the second evaporator 17, where it absorbs heat from an external heat source. Next, the gaseous carbon dioxide exiting the second evaporator 17 is still not very hot, and is reheated at the fourth heat exchanger 18 using heat from the thermal management module. This heat is the high-grade compression heat recovered and stored during the energy storage process. Through this step, the carbon dioxide gas is further superheated, becoming high-temperature, high-pressure supercritical or gaseous carbon dioxide. Finally, the high-temperature, high-pressure carbon dioxide enters the turbine 19, where it expands and performs work. The carbon dioxide's pressure decreases and its volume expands in the turbine 19, driving the impeller to rotate, converting the fluid's internal energy and pressure energy into mechanical energy, and driving the generator to generate electricity.

[0074] In this embodiment, by using the staged heating strategy of the expansion power generation module, low-grade industrial waste heat and high-grade compression heat are used for the most suitable thermodynamic processes, which greatly reduces the loss of high-grade heat and improves the overall heat-to-work conversion efficiency.

[0075] In one embodiment of this application, the liquefaction circulation module includes: The second condenser 21 is configured to condense gaseous carbon dioxide into liquid using a cooling medium from the thermal management module; A throttling unit, connected to the outlet of the second condenser 21, is used to throttle and reduce the pressure of liquid carbon dioxide; A gas-liquid separation unit is connected to the outlet of the throttling unit, and the liquid phase outlet of the gas-liquid separation unit is connected to the low-pressure liquid carbon dioxide storage unit 1. The gas-liquid separation unit is configured to send the depressurized gas-liquid two-phase carbon dioxide into the low-pressure liquid carbon dioxide storage unit 1.

[0076] In one embodiment of this application, as shown in the appendix Figure 1As shown, the components of the liquefaction circulation module are connected sequentially according to the process flow, including: The inlet of the second condenser 21 is connected to the outlet of the expansion power generation module (specifically, the outlet of the third mixer 20) via a pipeline, receiving low-temperature, low-pressure gaseous carbon dioxide from the turbine 19. The throttling unit can specifically be a second throttling valve 22. The inlet of the second throttling valve 22 is connected to the outlet of the second condenser 21. The gas-liquid separation unit can be a second gas-liquid separator 23. The inlet of the second gas-liquid separator 23 is connected to the outlet of the second throttling valve 22, and its liquid phase outlet is connected to the inlet of the low-pressure liquid carbon dioxide storage unit 1 via a pipeline.

[0077] Specifically, the second condenser 21 uses the cooling medium from the thermal management module (i.e., ambient temperature cooling water from the cold water tank 25) to condense the gaseous carbon dioxide from the turbine 19 outlet into a liquid state. The liquid carbon dioxide flowing out of the second condenser 21 has a relatively high pressure and needs to be depressurized. Subsequently, the throttling unit creates a local resistance to throttle and depressurize the liquid carbon dioxide, reducing both its pressure and temperature simultaneously. Finally, the depressurized carbon dioxide becomes a low-temperature gas-liquid two-phase mixture. The gas-liquid separation unit uses gravity or centrifugation to separate the liquid carbon dioxide from the unliquefied gaseous carbon dioxide in the mixture. The separated liquid carbon dioxide flows out from its liquid phase outlet and is directly sent to the low-pressure liquid carbon dioxide storage unit 1.

[0078] In this embodiment, the liquefaction and circulation module ensures that the carbon dioxide in the system can be effectively recovered and reused, enabling the system to operate continuously and stably.

[0079] In one embodiment of this application, the liquefaction circulation module further includes an auxiliary compressor 24; The inlet of the auxiliary compressor 24 is connected to the gas phase outlet of the gas-liquid separation unit, and the outlet is connected to the inlet pipe of the second condenser 21.

[0080] In this embodiment, as shown in the appendix Figure 1 As shown, the inlet of the auxiliary compressor 24 is connected to the gas phase outlet of the gas-liquid separation unit. Specifically, its inlet is connected to the gas phase outlet at the top of the second gas-liquid separator 23 via a pipeline. The outlet of the auxiliary compressor 24 is connected to the inlet pipeline of the second condenser 21. Specifically, its outlet is connected to the inlet of the third mixer 20 via a pipeline, thereby merging with the inlet pipeline of the second condenser 21.

[0081] After being condensed by the second condenser 21 and throttled by the second throttling valve 22, the carbon dioxide entering the second gas-liquid separator 23 is in a two-phase state of gas and liquid. The separated gaseous carbon dioxide has low pressure and a corresponding low saturation temperature; direct discharge would result in continuous carbon dioxide loss. Attempting to condense it directly with room temperature water would be inefficient or impossible due to the small temperature difference. Therefore, the auxiliary compressor 24 is used to compress this unliquefied, low-pressure gaseous carbon dioxide, increasing its pressure.

[0082] In this embodiment, the auxiliary compressor 24 ensures that all gaseous carbon dioxide in the system can eventually be liquefied and returned to the storage tank, thus guaranteeing the long-term continuous and stable operation of the system.

[0083] In one embodiment of this application, the external heat source is industrial low-temperature waste heat. Industrial low-temperature waste heat refers to thermal energy generated during industrial production processes that is typically difficult to utilize economically and efficiently using traditional technologies due to its low temperature, and is ultimately wasted by being discharged into the environment. In this embodiment, the industrial low-temperature waste heat can be applied to the first evaporator 4 in the vaporization branch and the second evaporator 17 in the expansion power generation module, thereby solving the problem of waste heat emission and reducing heat waste.

[0084] In another embodiment of this application, simulation calculations were performed using a set of data to characterize the performance of the system. In this example, the fluid to be cooled was set to ethylene (pressure 3.5 MPa, temperature 35°C), and the fluid to be heated was set to water (pressure 2 MPa, temperature 20°C). Tables 1, 2, and 3 were obtained.

[0085] Table 1. Main operating parameters under maximum cooling capacity mode

[0086] Table 2 Main operating parameters under zero cooling power mode

[0087] Table 3 Comparison of system performance parameters under two power modes

[0088] Note: Table 3 is based on simulation calculations using a self-developed program.

[0089] Formula 1:

[0090] in, For cycle efficiency, This represents the net output power during the energy release phase. For the energy release phase, output heat power. To output cooling power during the energy storage phase, The power consumed by the compressor during the energy storage phase. This is the sum of the waste heat input power during the energy storage and release phases. For the energy release duration, this scheme sets the energy release duration to 4 hours. For energy storage duration, this plan sets the energy storage duration at 4 hours. For the coefficient of performance (COP), this scheme sets... , For the coefficient of performance (COP), this scheme is set as follows: .

[0091] Formula 2:

[0092] in, This is the sum of the volumes of the low-pressure side storage tank and the high-pressure side storage tank.

[0093] As shown in Table 3, using the system's cycle efficiency and energy storage density as evaluation indicators, the scheme employing the maximum cooling power mode is superior to the zero cooling power mode, achieving a cycle efficiency of 116.88% and an energy storage density of 28.91 kWh / m³. 3 .

[0094] like Figure 2 As shown, when the maximum cooling mode of the system of the present invention is compared with the existing combined cooling, heating and power system, under the premise of equal power generation, the cooling capacity of the system of the present invention is increased by 167% compared with the existing combined cooling, heating and power system, and the heating capacity of the system of the present invention is increased by 541% compared with the existing combined cooling, heating and power system.

[0095] In summary, the liquid carbon dioxide energy storage system of this invention can make reasonable use of the low-temperature waste heat in industrial scenarios. Without affecting the set power generation, it can adjust the amount and temperature level of the output cooling capacity according to the actual cooling needs of the industrial scenario. At the same time, it can also provide surplus compression heat to meet certain heat demands, thus possessing good engineering application value.

[0096] In addition, the present invention also provides an energy supply device, which includes the liquid carbon dioxide energy storage system described above.

[0097] In the description of this invention, it should be understood that 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, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0098] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0099] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0100] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A liquid carbon dioxide energy storage system, characterized in that, The system includes: Low-pressure liquid carbon dioxide storage unit and high-pressure liquid carbon dioxide storage unit; The vaporization and refrigeration module is connected to the outlet of the low-pressure liquid carbon dioxide storage unit and is configured to vaporize carbon dioxide, or to use the latent heat of phase change of carbon dioxide output from the low-pressure liquid carbon dioxide storage unit to output cooling capacity and output the vaporized gaseous carbon dioxide. The compression heat exchange module is connected to the outlet of the vaporization and refrigeration module and is configured to compress the gaseous carbon dioxide output by the vaporization and refrigeration module, recover the heat generated during the compression process and store it in the thermal management module, and condense the compressed high-pressure gaseous carbon dioxide into high-pressure liquid carbon dioxide and send it into the high-pressure liquid carbon dioxide storage unit. A thermal management module, connected to the compression heat exchange module, is configured to output heat externally using stored compression heat. An expansion power generation module, connected to the high-pressure liquid carbon dioxide storage unit, is configured to pressurize the high-pressure liquid carbon dioxide and vaporize it using an external heat source and the heat stored in the thermal management module, and then use the vaporized high-temperature and high-pressure carbon dioxide to expand and generate electricity. The liquefaction circulation module is connected to the outlet of the expansion power generation module and the low-pressure liquid carbon dioxide storage unit, respectively, and is configured to liquefy the gaseous carbon dioxide after expansion power generation and send it back to the low-pressure liquid carbon dioxide storage unit.

2. The system as described in claim 1, characterized in that, The vaporization and refrigeration module includes a vaporization branch and a refrigeration branch connected in parallel. The vaporization branch is equipped with a first evaporator, and the vaporization branch is configured to absorb external low-temperature waste heat through the first evaporator to vaporize liquid carbon dioxide. The refrigeration branch is equipped with a first heat exchanger, and the refrigeration branch is configured to output cooling capacity to the outside by utilizing the latent heat of phase change of liquid carbon dioxide through the first heat exchanger.

3. The system as described in claim 2, characterized in that, The refrigeration branch is equipped with an adjustable flow valve connected to the first heat exchanger, configured to control the temperature level of the cooling capacity generated by the liquid carbon dioxide by adjusting the throttling pressure of the liquid carbon dioxide.

4. The system as described in claim 2, characterized in that, The system also includes a distributor, the inlet of which is connected to the low-pressure liquid carbon dioxide storage unit, and the outlet of which is connected to the vaporization branch and the refrigeration branch, respectively.

5. The system as described in claim 4, characterized in that, The distributor is configured to distribute all liquid carbon dioxide from the low-pressure liquid carbon dioxide storage unit to the vaporization branch, all to the refrigeration branch, or in any proportion to both the vaporization branch and the refrigeration branch.

6. The system as described in claim 1, characterized in that, The compression heat exchange module includes: The compression heat exchange submodule is configured to compress gaseous carbon dioxide, and cool the gaseous carbon dioxide and recover the heat of compression during the compression process. The first condenser, connected to the compression heat exchange submodule, is configured to condense the compressed high-pressure gaseous carbon dioxide into liquid carbon dioxide and send it into the high-pressure liquid carbon dioxide storage unit.

7. The system as described in claim 6, characterized in that, The compression heat exchange submodule includes a first compression unit and a second compression unit; The inlet of the first compression unit is connected to the outlet of the refrigeration branch in the vaporization and refrigeration module, and is configured to compress and exchange heat for gaseous carbon dioxide in the refrigeration branch. The inlet of the second compression unit is connected to the outlet of the first compression unit and the vaporization branch in the vaporization and refrigeration module, respectively, and is configured to perform compression heat exchange on the gaseous carbon dioxide compressed by the first compression unit and the gaseous carbon dioxide in the vaporization branch.

8. The system as described in claim 7, characterized in that, The first compression unit includes a first compressor and a second heat exchanger that are interconnected, and the second compression unit includes a second compressor and a third heat exchanger that are interconnected. The inlet of the first compressor is connected to the outlet of the refrigeration branch, the outlet of the second heat exchanger is connected to the inlet of the second compressor, and the outlet of the third heat exchanger is connected to the inlet of the first condenser.

9. The system as described in claim 1, characterized in that, The thermal management module also includes a heat storage device and a cold storage device; The cold storage unit is configured to provide a cooling medium to the compression heat exchange submodule in the compression heat exchange module; The heat storage device is configured to store the compression heat recovered from the compression heat exchange module and to provide heat to the expansion power generation module and the thermal management module.

10. The system as described in claim 9, characterized in that, The thermal management module also includes a heating submodule, the inlet of which is connected to the outlet of the heat storage unit, and the outlet of which is connected to the cold storage unit; the inlet of the heating submodule is configured to connect to an external fluid to be heated. The heating submodule is configured to use the hot water provided by the heat storage unit to heat the external fluid to be heated, so as to output heat to the outside.

11. The system as claimed in claim 1, characterized in that, The expansion power generation module comprises the following components connected in sequence: A hydraulic pump, the inlet of which is connected to the high-pressure liquid carbon dioxide storage unit, is configured to pressurize the liquid carbon dioxide in the high-pressure liquid carbon dioxide storage unit; The second evaporator, connected to the outlet of the hydraulic pump, is configured to absorb heat from an external heat source and vaporize pressurized liquid carbon dioxide. The fourth heat exchanger, connected to the outlet of the second evaporator, is configured to reheat gaseous carbon dioxide using heat from the thermal management module; The turbine is connected to the outlet of the fourth heat exchanger and is used to generate electricity by expanding heated gaseous carbon dioxide.

12. The system as claimed in claim 1, characterized in that, The liquefaction circulation module includes: The second condenser is configured to condense gaseous carbon dioxide into liquid carbon dioxide; A throttling unit, connected to the outlet of the second condenser, is used to throttle and reduce the pressure of liquid carbon dioxide; A gas-liquid separation unit is connected to the outlet of the throttling unit, and the liquid phase outlet of the gas-liquid separation unit is connected to the low-pressure liquid carbon dioxide storage unit. The gas-liquid separation unit is configured to send depressurized gas-liquid two-phase carbon dioxide into the low-pressure liquid carbon dioxide storage unit.

13. The system as described in claim 12, characterized in that, The liquefaction circulation module also includes an auxiliary compressor; The inlet of the auxiliary compressor is connected to the gas phase outlet of the gas-liquid separation unit, and the outlet is connected to the inlet pipe of the second condenser.

14. The system as claimed in claim 1, characterized in that, The external heat source is industrial low-temperature waste heat.

15. An energy supply device, characterized in that, The device includes the liquid carbon dioxide energy storage system according to any one of claims 1-14.

Images