A liquid carbon dioxide energy storage system with dual-process coupling and shared heat exchanger

Abstract

The present invention discloses a liquid carbon dioxide energy storage system with dual-process coupled shared heat exchangers, in which the energy storage path and energy release path of the liquid carbon dioxide energy storage system share the same pipeline in the first heat exchange component and the second heat exchange component, reducing the number of heat exchangers required in the carbon dioxide energy storage system, thereby reducing the footprint of the heat exchanger and reducing the initial investment cost. At the same time, the present invention integrates the carbon dioxide heat exchange device with the phase change material cold and heat storage device, significantly improves the heat exchange effect through direct contact heat exchange, simplifies the carbon dioxide energy storage system, reduces equipment costs, and reduces floor space; in addition, the present invention uses phase change materials and carbon dioxide heat exchange in both the first heat exchange component and the second heat exchange component to store cold and heat, greatly improving the energy density of energy storage.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to a liquid carbon dioxide energy storage system with a dual-process coupled shared heat exchanger. Background Art

[0002] In the context of rapid development of new energy, new energy storage has become one of the key links in building a new power system. Liquid carbon dioxide energy storage converts electrical energy into thermal energy and potential energy of carbon dioxide to achieve energy storage. Compared with air, carbon dioxide is easier to liquefy, does not need to rely on underground caves, and has more flexible site selection. In addition, carbon dioxide has high specific heat capacity, good heat transfer performance, lower parasitic energy consumption, and higher system efficiency. Therefore, liquid carbon dioxide energy storage has the advantages of ultra-long time, large scale, high flexibility, high efficiency, and high energy storage density, and has more development prospects.

[0003] However, the liquid carbon dioxide energy storage system requires a large amount of cold and heat to liquefy and gasify carbon dioxide. The heat transfer coefficient of conventional heat exchangers is low, resulting in the heat exchange system occupying too much area. In addition, a series of high and low temperature heat exchangers are required in the liquid carbon dioxide energy storage system. The larger the energy storage scale of the energy storage system, the greater the heat exchange capacity, and the size and cost of the heat exchanger increase accordingly, resulting in an increase in the initial investment in system construction. Summary of the invention

[0004] The object of the present invention is to provide a liquid carbon dioxide energy storage system with a dual-process coupled shared heat exchanger.

[0005] The present invention provides a liquid carbon dioxide energy storage system with a dual-process coupled shared heat exchanger, which includes a low-pressure liquid storage module, a first heat exchange component, a compressor, a second heat exchange component, a high-pressure liquid storage module and an expander. The low-pressure liquid storage module, the first heat exchange component, the compressor, the second heat exchange component and the high-pressure liquid storage module form an energy storage passage. The high-pressure liquid storage module, the second heat exchange component, the expander, the first heat exchange component and the low-pressure liquid storage module form an energy release passage. The first heat exchange component and the second heat exchange component each include one or multiple heat exchangers connected in sequence; the energy storage passage and the energy release passage share the same pipeline in the first heat exchange component and the second heat exchange component. During operation, the energy storage system switches between an energy storage state and an energy release state;

[0006] In the energy storage state, the carbon dioxide output by the low-pressure liquid storage module is input into the energy storage path, and is stored in the high-pressure liquid storage module through the processes of heating, compressor work and pressurization, and liquefaction;

[0007] In the energy release state, the liquid carbon dioxide in the high-pressure liquid storage module is input into the energy release passage, and is stored in the low-pressure liquid storage module through the processes of gasification, energy release and pressure reduction by the expander, and temperature reduction.

[0008] Preferably, the low-pressure liquid storage module is a low-pressure storage tank; a throttle valve in the energy storage passage and a first on-off valve in the energy release passage are provided between the low-pressure liquid storage module and the first heat exchange component; during the energy storage process, the throttle valve is opened and the first on-off valve is closed, and the liquid carbon dioxide output by the low-pressure liquid storage module has a reduced flow cross-sectional area when passing through the throttle valve and is converted into gas-liquid two-phase carbon dioxide; during the energy release process, the throttle valve is closed and the first on-off valve is opened.

[0009] Preferably, the input and output ends of the compressor are both provided with a second on-off valve in an energy storage path; the input and output ends of the expander are both provided with a third on-off valve in an energy release path. In the energy storage state, the second on-off valve is opened and the third on-off valve is closed; in the energy release state, the second on-off valve is closed and the third on-off valve is opened.

[0010] Preferably, the multiple heat exchangers are all connected to the heat storage tank and the cold storage tank; in the first heat exchange component, the cold released by the carbon dioxide in the energy storage state is stored in the cold storage tank by heat exchange between the heat exchanger and the heat exchange medium, and in the energy release state, the carbon dioxide is supplied for cooling by heat exchange between the heat exchanger and the heat exchange medium.

[0011] In the second heat exchange component, the heat released by the carbon dioxide in the energy storage state is stored in the heat storage tank by heat exchange between the heat exchanger and the heat exchange medium, and in the energy release state, the heat is supplied to the carbon dioxide for heating by heat exchange between the heat exchanger and the heat exchange medium.

[0012] Preferably, the first heat exchange component and the second heat exchange component both use heat exchangers with phase change materials. In the first heat exchange component, the cold released by carbon dioxide in the energy storage state is stored in the phase change material, and in the energy release state, it is supplied to carbon dioxide for cooling. In the second heat exchange component, the heat released by carbon dioxide in the energy storage state is stored in the phase change material, and in the energy release state, it is supplied to carbon dioxide for heating.

[0013] Preferably, the first heat exchange component comprises a plurality of heat exchangers, and along the direction from the low-pressure liquid storage module to the high-pressure liquid storage module, the phase change temperatures of the phase change materials stored in the plurality of heat exchangers in the first heat exchange component increase successively, and absorb the cold released by the carbon dioxide step by step in the energy storage state, and provide cold to the carbon dioxide step by step in the energy release state; the second heat exchange component comprises a plurality of heat exchangers, and along the direction from the high-pressure liquid storage module to the low-pressure liquid storage module, the phase change temperatures of the phase change materials stored in the plurality of heat exchangers in the second heat exchange component increase successively, and absorb the heat released by the carbon dioxide step by step in the energy storage state, and provide heat to the carbon dioxide step by step in the energy release state.

[0014] Preferably, the low-pressure liquid storage module comprises two liquid storage tanks and two throttle valves; the two liquid storage tanks are provided with a liquid phase output port, a two-phase input port, a gas phase input port and a gas phase output port; the liquid phase output ports of the two liquid storage tanks are connected to the two-phase input ports of the two liquid storage tanks through independent throttle valves and pipelines respectively; phase change materials are stored in both liquid storage tanks;

[0015] In the initial state, both liquid storage tanks store liquid phase change materials and one of the liquid storage tanks stores liquid energy storage medium, or the two liquid storage tanks store liquid phase change materials and solid phase change materials respectively; in the liquid storage tank storing both liquid phase change materials and liquid energy storage medium, the liquid phase change material and the liquid energy storage medium are naturally layered; the liquid energy storage medium is above the liquid phase change material;

[0016] The low-pressure liquid storage module has two stable states, namely a stored state and a non-stored state; in the stored state, both liquid storage tanks store liquid phase change materials, and one of the liquid storage tanks stores liquid energy storage media; in the non-storage state, the two liquid storage tanks store liquid phase change materials and solid phase change materials respectively, and neither stores energy storage media.

[0017] When the energy storage medium needs to be output, the liquid storage tank storing the liquid energy storage medium is used as the output tank, and the other liquid storage tank is used as the gasification tank; the throttle valve between the liquid phase output port of the output tank and the two-phase input port of the gasification tank is opened, and the liquid energy storage medium in the output tank passes through the opened throttle valve under the action of the pressure difference, and is converted into a gas-liquid two-phase energy storage medium under the action of throttling gasification, and enters the gasification tank; the gas-liquid two-phase energy storage medium directly contacts and exchanges heat with the liquid phase change material in the gasification tank; the liquid phase change material cools down and solidifies, and the gas-liquid two-phase energy storage medium is further gasified into a gaseous energy storage medium and output;

[0018] When energy storage medium needs to be stored, the gaseous energy storage medium is input into the liquid storage tank containing the solid phase change material; the solid phase change material and the gaseous energy storage medium are in direct contact and heat exchange, and the solid phase change material is liquefied into liquid phase change material; the gaseous energy storage medium is liquefied into liquid energy storage medium for storage;

[0019] In the process of outputting and storing energy storage medium, the internal states of the two liquid storage tanks are exchanged, that is, the original output tank becomes the new vaporization tank; the original vaporization tank becomes the new output tank.

[0020] Preferably, the liquid storage tank is provided with a carbon dioxide storage area and a phase change material storage area arranged vertically. The liquid phase output port and the gas phase output port of the liquid storage tank are both connected to the carbon dioxide storage area; the two-phase input port and the gas phase input port of the liquid storage tank are both connected to the phase change material storage area.

[0021] Preferably, the liquid phase output port and the gas phase output port are opened at the bottom of the carbon dioxide storage area, and the two-phase input port and the gas phase input port are opened at the bottom of the phase change material storage area.

[0022] Preferably, on-off valves are provided at the gas phase input port and the gas phase output port of the two liquid storage tanks.

[0023] The present invention has the following beneficial effects:

[0024] 1. The energy storage passage and the energy release passage of the present invention share the same pipeline in the first heat exchange component and the second heat exchange component, which reduces the number of heat exchangers required in the carbon dioxide energy storage system, thereby reducing the footprint of the heat exchanger and reducing the initial investment cost.

[0025] 2. The present invention integrates the carbon dioxide heat exchange device with the phase change material cold and heat storage device, significantly improves the heat exchange effect through direct contact heat exchange, simplifies the carbon dioxide energy storage system, reduces equipment costs, and reduces floor space; at the same time, the present invention uses phase change materials and carbon dioxide heat exchange in both the first heat exchange component and the second heat exchange component to store cold and heat, greatly improving the energy storage energy density. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the system structure of Example 1 of the present invention.

[0027] Figure 2 Schematic diagram of the system structure in the energy storage state of Example 2 of the present invention.

[0028] Figure 3 Schematic diagram of the system structure in the energy release state of Example 2 of the present invention.

[0029] Figure numerals: 1. low-pressure liquid storage module; 2. first heat exchange component; 3. compressor; 4. second heat exchange component; 5. high-pressure liquid storage module; 6. expander; 7. throttle valve; 8. first on-off valve; 9. second on-off valve; 10. third on-off valve. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] Example 1

[0032] like Figure 1As shown, a liquid carbon dioxide energy storage system with dual-process coupling and shared heat exchanger includes a low-pressure liquid storage module 1, a first heat exchange component 2, a compressor 3, a second heat exchange component 4, a high-pressure liquid storage module 5 and an expander 6. The low-pressure liquid storage module 1, the first heat exchange component 2, the compressor 3, the second heat exchange component 4 and the high-pressure liquid storage module 5 form an energy storage passage. The high-pressure liquid storage module 5, the second heat exchange component 4, the expander 6, the first heat exchange component 2 and the low-pressure liquid storage module 1 form an energy release passage. The low-pressure liquid storage module 1 and the first heat exchange component 2 are provided with a throttle valve 7 in the energy storage passage and a first on-off valve 8 in the energy release passage; the input end and the output end of the compressor 3 are both provided with a second on-off valve 9 in the energy storage passage; the input end and the output end of the expander 6 are both provided with a third on-off valve 10 in the energy release passage. The first heat exchange component 2 and the second heat exchange component 4 each include two heat exchangers connected in sequence, and all heat exchangers are connected to the heat storage tank and the cold storage tank. During operation, the energy storage system switches between an energy storage state and an energy release state.

[0033] In the energy storage state, the throttle valve 7 and the second on-off valve 9 are opened, and the first on-off valve 8 and the third on-off valve 10 are closed; the liquid carbon dioxide in the low-pressure liquid storage module 1 passes through the opened throttle valve 7 under the action of the pressure difference, and is converted into gas-liquid two-phase carbon dioxide under the action of throttling gasification, and enters the first heat exchange component 2. The two heat exchangers in the first heat exchange component 2 respectively exchange heat with the carbon dioxide input into the first heat exchange component 2 through the heat exchange medium input from the corresponding heat storage tank, so that the gas-liquid two-phase carbon dioxide is gradually heated in the first heat exchange component 2, and the gaseous carbon dioxide is output, and the heat exchange medium is transported to the corresponding cold storage tank for storage. The gaseous carbon dioxide output from the first heat exchange component 2 is input into the compressor 3 through the opened second on-off valve 9; the compressor 3 consumes electric energy to pressurize the gaseous carbon dioxide output from the first heat exchange component 2, and then inputs it into the second heat exchange component 4 through the opened second on-off valve 9. The two heat exchangers in the second heat exchange component 4 respectively exchange heat with the carbon dioxide input into the second heat exchange component 4 through the heat exchange medium input from the corresponding cold storage tank, so that the gaseous carbon dioxide is gradually cooled in the second heat exchange component 4, and liquid carbon dioxide is obtained and transported to the high-pressure liquid storage module 5 for storage, and the heat exchange medium is transported to the corresponding heat storage tank for storage to complete energy storage.

[0034] In the energy release state, the throttle valve 7 and the second on-off valve 9 are closed, and the first on-off valve 8 and the third on-off valve 10 are opened; the liquid carbon dioxide in the high-pressure liquid storage module 5 is input into the second heat exchange component 4; the two heat exchangers in the second heat exchange component 4 respectively exchange heat with the carbon dioxide input into the second heat exchange component 4 through the heat exchange medium input from the corresponding heat storage tank, so that the liquid carbon dioxide is gradually heated in the second heat exchange component 4, and gaseous carbon dioxide is obtained, and is input into the expander 8 through the opened third on-off valve 10, and the heat exchange medium is transported to the corresponding cold storage tank for storage. The expander 8 performs work externally through the expansion of gaseous carbon dioxide and releases energy to complete the energy release. The carbon dioxide output by the expander 8 is input into the first heat exchange component 2 through the opened third on-off valve 10. The two heat exchangers in the first heat exchange component 2 respectively exchange heat with the carbon dioxide input into the first heat exchange component 2 through the heat exchange medium input from the corresponding heat storage tank, so that the gaseous carbon dioxide is gradually cooled in the first heat exchange component 2, and liquid carbon dioxide is obtained and transported to the low-pressure liquid storage module 1 for storage through the first on-off valve 8, and the heat exchange medium is transported to the corresponding heat storage tank for storage.

[0035] Example 2

[0036] like Figure 2 and 3 As shown, a liquid carbon dioxide energy storage system with a dual-process coupled shared heat exchanger includes a low-pressure liquid storage module 1, a first heat exchange component 2, a compressor 3, a second heat exchange component 4, a high-pressure liquid storage module 5 and an expander 6. The low-pressure liquid storage module 1, the first heat exchange component 2, the compressor 3, the second heat exchange component 4 and the high-pressure liquid storage module 5 form an energy storage path. The high-pressure liquid storage module 5, the second heat exchange component 4, the expander 6, the first heat exchange component 2 and the low-pressure liquid storage module 1 form an energy release path. The input and output ends of the compressor 3 are both provided with a second on-off valve 9 in the energy storage path; the input and output ends of the expander 6 are both provided with a third on-off valve 10 in the energy release path. The first heat exchange component 2 includes a heat exchanger; the second heat exchange component 4 includes two heat exchangers connected in sequence; phase change materials are stored in all heat exchangers. During operation, the energy storage system switches between an energy storage state and an energy release state.

[0037] The low-pressure liquid storage module 1 includes two liquid storage tanks and two throttle valves; both liquid storage tanks are provided with a carbon dioxide storage area and a phase change material storage area arranged up and down. The two liquid storage tanks are provided with a liquid phase output port, a two-phase input port and a gas phase inlet and outlet. The liquid phase output port and the gas phase inlet and outlet of the liquid storage tank are arranged at the bottom of the carbon dioxide storage area, and the two-phase input port is arranged at the bottom of the phase change material storage area. The liquid phase output ports of the two liquid storage tanks are connected to the two-phase input ports of the two liquid storage tanks through independent throttle valves and pipelines respectively; the gas phase inlet and outlet of the two liquid storage tanks are provided with on-off valves; and phase change materials (PCM) are stored in both liquid storage tanks.

[0038] In some embodiments, the gas output ports of the two liquid storage tanks are arranged at the bottom of the carbon dioxide storage area, and the gas input ports are arranged at the bottom of the phase change material storage area. On-off valves are arranged at the gas output ports and gas input ports of the two liquid storage tanks.

[0039] In the initial state, both liquid storage tanks store liquid phase change materials, and one of the liquid storage tanks stores liquid carbon dioxide; or the two liquid storage tanks store liquid phase change materials and solid phase change materials respectively. In the liquid storage tanks storing both liquid phase change materials and liquid carbon dioxide, the liquid phase change materials and liquid carbon dioxide are naturally separated into layers; due to different densities, the liquid carbon dioxide is above the liquid phase change materials.

[0040] The low-pressure liquid storage module 1 has two stable states, namely a stored state and a non-stored state. In the stored state, both liquid storage tanks store liquid phase change materials, and one of the liquid storage tanks stores liquid carbon dioxide; in the non-stored state, the two liquid storage tanks store liquid phase change materials and solid phase change materials, respectively, and neither stores carbon dioxide.

[0041] When the low-pressure liquid storage module 1 outputs carbon dioxide, the liquid storage tank storing liquid carbon dioxide is used as the output tank, and the other liquid storage tank is used as the gasification tank. The throttle valve between the liquid phase output port of the output tank and the two-phase input port of the gasification tank and the on-off valve at the gas phase inlet and outlet of the gasification tank are opened, and the liquid carbon dioxide in the output tank passes through the opened throttle valve under the action of the pressure difference, and is converted into gas-liquid two-phase carbon dioxide under the action of throttling gasification and enters the gasification tank; the gas-liquid two-phase carbon dioxide is in direct contact with the liquid phase change material in the gasification tank for heat exchange; the liquid phase change material cools down and solidifies, and the gas-liquid two-phase carbon dioxide is further gasified into gaseous carbon dioxide and output;

[0042] When carbon dioxide is stored in the low-pressure liquid storage module 1, gaseous carbon dioxide is input into the liquid storage tank containing the solid phase change material; the solid phase change material and the gaseous carbon dioxide are in direct contact for heat exchange, and the solid phase change material is liquefied into liquid phase change material; the gaseous carbon dioxide is liquefied into liquid carbon dioxide for storage.

[0043] In the process of outputting and storing carbon dioxide, the internal states of the two storage tanks are exchanged, that is, the original output tank becomes the new gasification tank; the original gasification tank becomes the new output tank.

[0044] In the energy storage state, the second on-off valve 9 is opened and the third on-off valve 10 is closed; the low-pressure liquid storage module 1 inputs gaseous carbon dioxide into the energy storage passage, and the gaseous carbon dioxide exchanges heat with the phase change material stored in the heat exchanger through the first heat exchange component 2 to increase the temperature of the gaseous carbon dioxide, and the cold released by the gaseous carbon dioxide is stored by the first heat exchange component 2; the gaseous carbon dioxide output by the first heat exchange component 2 is input into the compressor 3 through the second on-off valve 9; the compressor 3 consumes electric energy to pressurize the gaseous carbon dioxide, and then inputs it into the second heat exchange component 4 through the second on-off valve 9. The second heat exchange component 4 exchanges heat with the gaseous carbon dioxide through the phase change materials stored in the two heat exchangers, reduces the temperature of the gaseous carbon dioxide, converts it into liquid carbon dioxide and inputs it into the high-pressure liquid storage module 5, and the heat released by the gaseous carbon dioxide is stored by the second heat exchange component 4.

[0045] In the energy release state, the second on-off valve 9 is closed and the third on-off valve 10 is opened; the high-pressure liquid storage module 5 inputs liquid carbon dioxide into the energy release passage; the liquid carbon dioxide exchanges heat with the phase change material stored in the heat exchanger through the second heat exchange component 4, increases the temperature of the gaseous carbon dioxide, converts the liquid carbon dioxide into gaseous carbon dioxide, and the cold released by the carbon dioxide is stored by the second heat exchange component 4; the gaseous carbon dioxide output by the second heat exchange component 4 is input to the expansion machine 6 through the third on-off valve 10; the expansion machine 6 performs work externally through the expansion of the gaseous carbon dioxide, releases energy, and inputs it into the first heat exchange component 2 through the third on-off valve 10. The gaseous carbon dioxide exchanges heat with the phase change material stored in the heat exchanger through the first heat exchange component 2, reduces the temperature of the gaseous carbon dioxide, and is stored in the low-pressure liquid storage module 1, and the heat released by the gaseous carbon dioxide is stored by the first heat exchange component 2.

[0046] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A liquid carbon dioxide energy storage system with dual-process coupling and shared heat exchanger, characterized in that: The energy storage system comprises a low-pressure liquid storage module (1), a first heat exchange component (2), a compressor (3), a second heat exchange component (4), a high-pressure liquid storage module (5) and an expander (6); the low-pressure liquid storage module (1), the first heat exchange component (2), the compressor (3), the second heat exchange component (4) and the high-pressure liquid storage module (5) form an energy storage path; the high-pressure liquid storage module (5), the second heat exchange component (4), the expander (6), the first heat exchange component (2) and the low-pressure liquid storage module (1) form an energy release path; the energy storage path and the energy release path share the same pipeline in both the first heat exchange component (2) and the second heat exchange component (4); during operation, the energy storage system switches between an energy storage state and an energy release state; In the energy storage state, the carbon dioxide output by the low-pressure liquid storage module (1) is input into the energy storage passage, and is sequentially stored in the high-pressure liquid storage module (5) through the processes of heating, pressurization by the compressor (3), and liquefaction; In the energy release state, the liquid carbon dioxide in the high-pressure liquid storage module (5) is input into the energy release passage, and is stored in the low-pressure liquid storage module (1) through the processes of gasification, energy release, pressure reduction, and temperature reduction by the expander (6); The low-pressure liquid storage module (1) is a low-pressure storage tank; a throttle valve (7) in an energy storage passage and a first on-off valve (8) in an energy release passage are provided between the low-pressure liquid storage module (1) and the first heat exchange component (2); during the energy storage process, the throttle valve (7) is opened, the first on-off valve (8) is closed, and the liquid carbon dioxide output by the low-pressure liquid storage module (1) is converted into gas-liquid two-phase carbon dioxide through the throttle valve (7); during the energy release process, the throttle valve (7) is closed, and the first on-off valve (8) is opened; The input end and the output end of the compressor (3) are both provided with a second on-off valve (9) in an energy storage path; the input end and the output end of the expander (6) are both provided with a third on-off valve (10) in an energy release path; in the energy storage state, the second on-off valve (9) is opened and the third on-off valve (10) is closed; in the energy release state, the second on-off valve (9) is closed and the third on-off valve (10) is opened; The first heat exchange component (2) and the second heat exchange component (4) each include one or a plurality of heat exchangers connected in sequence; all heat exchangers are connected to the heat storage tank and the cold storage tank; in the first heat exchange component (2), the cold energy released by the carbon dioxide in the energy storage state is stored in the cold storage tank by heat exchange between the heat exchanger and the heat exchange medium, and in the energy release state, the cold energy is supplied to the carbon dioxide for cooling by heat exchange between the heat exchanger and the heat exchange medium; In the second heat exchange component (4), the heat released by the carbon dioxide in the energy storage state is stored in the heat storage tank by means of heat exchange between the heat exchanger and the heat exchange medium, and in the energy release state, the heat is supplied to the carbon dioxide for heating by means of heat exchange between the heat exchanger and the heat exchange medium; The first heat exchange component (2) and the second heat exchange component (4) both use heat exchangers containing phase change materials; in the first heat exchange component (2), the cold released by the carbon dioxide in the energy storage state is stored in the phase change material, and in the energy release state, it is supplied to the carbon dioxide for cooling; in the second heat exchange component (4), the heat released by the carbon dioxide in the energy storage state is stored in the phase change material, and in the energy release state, it is supplied to the carbon dioxide for heating; The low-pressure liquid storage module (1) comprises two liquid storage tanks and two throttle valves; the two liquid storage tanks are provided with a liquid phase output port, a two-phase input port, a gas phase input port and a gas phase output port; the liquid phase output ports of the two liquid storage tanks are connected to the two-phase input ports of the two liquid storage tanks via independent throttle valves and pipelines respectively; phase change materials are stored in the two liquid storage tanks; In the initial state, both liquid storage tanks store liquid phase change materials and one of the liquid storage tanks stores liquid energy storage medium, or the two liquid storage tanks store liquid phase change materials and solid phase change materials respectively; in the liquid storage tank storing both liquid phase change materials and liquid energy storage medium, the liquid phase change material and the liquid energy storage medium are naturally layered; the liquid energy storage medium is above the liquid phase change material; The low-pressure liquid storage module (1) has two stable states, namely a stored state and a non-stored state; in the stored state, both liquid storage tanks store liquid phase change material, and one of the liquid storage tanks stores liquid energy storage medium; in the non-stored state, the two liquid storage tanks store liquid phase change material and solid phase change material respectively, and neither of them stores energy storage medium; When the energy storage medium needs to be output, the liquid storage tank storing the liquid energy storage medium is used as the output tank, and the other liquid storage tank is used as the gasification tank; the throttle valve between the liquid phase output port of the output tank and the two-phase input port of the gasification tank is opened, and the liquid energy storage medium in the output tank passes through the opened throttle valve under the action of the pressure difference, and is converted into a gas-liquid two-phase energy storage medium under the action of throttling gasification, and enters the gasification tank; the gas-liquid two-phase energy storage medium directly contacts and exchanges heat with the liquid phase change material in the gasification tank; the liquid phase change material cools down and solidifies, and the gas-liquid two-phase energy storage medium is further gasified into a gaseous energy storage medium and output; When energy storage medium needs to be stored, the gaseous energy storage medium is input into the liquid storage tank containing the solid phase change material; the solid phase change material and the gaseous energy storage medium are in direct contact and heat exchange, and the solid phase change material is liquefied into liquid phase change material; the gaseous energy storage medium is liquefied into liquid energy storage medium for storage; In the process of outputting and storing energy storage medium, the internal states of the two liquid storage tanks are exchanged, that is, the original output tank becomes the new vaporization tank; the original vaporization tank becomes the new output tank.

2. According to claim 1, a liquid carbon dioxide energy storage system with dual-process coupling and a shared heat exchanger, characterized in that: Along the direction from the low-pressure liquid storage module (1) to the high-pressure liquid storage module (5), the phase change temperature of the phase change material stored in the heat exchanger in the first heat exchange component (2) increases successively, and in the energy storage state, the heat released by the carbon dioxide is absorbed step by step, and in the energy release state, the heat is provided to the carbon dioxide step by step; along the direction from the high-pressure liquid storage module (5) to the low-pressure liquid storage module (1), the phase change temperature of the phase change material stored in the heat exchanger in the second heat exchange component (4) increases successively, and in the energy storage state, the heat released by the carbon dioxide is absorbed step by step, and in the energy release state, the heat is provided to the carbon dioxide step by step.

3. The liquid carbon dioxide energy storage system with dual-process coupling and shared heat exchanger according to claim 1, characterized in that: On-off valves are provided at the gas phase input ports and gas phase output ports of the two liquid storage tanks.

4. The liquid carbon dioxide energy storage system with dual-process coupling and shared heat exchanger according to claim 1, characterized in that: The liquid storage tank is provided with a carbon dioxide storage area and a phase change material storage area arranged up and down; the liquid phase output port and the gas phase output port of the liquid storage tank are both connected to the carbon dioxide storage area; the two-phase input port and the gas phase input port of the liquid storage tank are both connected to the phase change material storage area.

5. A liquid carbon dioxide energy storage system with dual-process coupling and a shared heat exchanger according to claim 4, characterized in that: The liquid phase output port and the gas phase output port are provided at the bottom of the carbon dioxide storage area, and the two-phase input port and the gas phase input port are provided at the bottom of the phase change material storage area.

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