Carbon dioxide energy storage cold and heat supply system utilizing off-peak electricity and operation method of carbon dioxide energy storage cold and heat supply system

Abstract

The invention discloses a carbon dioxide energy storage cooling and heating system utilizing off-peak electricity and an operation method of the carbon dioxide energy storage cooling and heating system. Comprising a carbon dioxide loop; the carbon dioxide loop comprises a liquid CO2 storage tank, a cold supply heat exchanger, a gaseous CO2 storage device, a compressor, a heat supply heat exchanger, a pressure reducing valve and a gas-liquid separator; an outlet of the liquid CO2 storage tank is connected with a CO2 side inlet of the cold supply heat exchanger; a CO2 side outlet of the cold supply heat exchanger is connected with an inlet of gaseous CO2 storage equipment; an outlet of the gaseous CO2 storage equipment is connected with an inlet of the compressor; an outlet of the compressor is connected with a CO2 side inlet of the heat supply heat exchanger; a CO2 side outlet of the heat supply heat exchanger is connected with an inlet of the pressure reducing valve; an outlet of the pressure reducing valve is connected with an inlet of the gas-liquid separator; a gas outlet of the gas-liquid separator is connected with an inlet of the compressor, and a liquid outlet of the gas-liquid separator is connected with an inlet of the liquid CO2 storage tank. According to the system, off-peak electricity can be fully utilized, energy storage and flexible supply of cold energy and heat energy are achieved, operation is reliable, the energy utilization efficiency is high, and economical efficiency is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of heating, ventilation and air conditioning, and in particular relates to a carbon dioxide energy storage cooling and heating system utilizing off-peak electricity and an operation method thereof. Background Art

[0002] The peak electricity consumption in summer is also the peak cooling consumption of refrigeration and air conditioning systems. The operation of air conditioning systems in summer has brought great pressure to the power system. Large cities even have to implement power restrictions to ensure the safety of electricity consumption during the peak electricity consumption period in summer. The power department implements peak-valley electricity prices to attract and guide its users to take measures to actively transfer part of the peak electricity consumption to the low electricity consumption period, reduce user electricity bills, reduce the peak-valley electricity consumption difference of the power grid, and improve the energy efficiency and safety of the power grid.

[0003] At present, HVAC systems usually use water storage or ice storage to achieve peak shifting and valley filling of air conditioning electricity consumption in summer. However, conventional water storage uses the sensible heat of water for cold storage, so it has the disadvantages of large water storage equipment, open system, easy entry of impurities into the chilled water system, and algae breeding. Although the conventional ice storage system uses the latent heat of water for cold storage, and the cold storage density is greatly improved compared with water storage, it has the disadvantages of complex system control and large initial investment. Summary of the invention

[0004] The object of the present invention is to overcome the above-mentioned shortcomings and deficiencies of the prior art and to provide a carbon dioxide energy storage cooling and heating system utilizing off-peak electricity and an operation method thereof.

[0005] The present invention is achieved through the following technical solutions: A carbon dioxide energy storage cooling and heating system utilizing off-peak electricity, comprising a carbon dioxide loop; The carbon dioxide circuit includes a liquid CO2 storage tank 1, a cooling heat exchanger 2, a gaseous CO2 storage device 4, a compressor 5, a heating heat exchanger 6, a pressure reducing valve 8, and a gas-liquid separator 9; The outlet of the liquid CO2 storage tank 1 is connected to the CO2 side inlet of the cooling heat exchanger 2; The CO2 side outlet of the cooling heat exchanger 2 is connected to the inlet of the gaseous CO2 storage device 4; The outlet of the gaseous CO2 storage device 4 is connected to the inlet of the compressor 5; The outlet of the compressor 5 is connected to the CO2 side inlet of the heat supply heat exchanger 6; The CO2 side outlet of the heat supply heat exchanger 6 is connected to the inlet of the pressure reducing valve 8; The outlet of the pressure reducing valve 8 is connected to the inlet of the gas-liquid separator 9; The gaseous outlet of the gas-liquid separator 9 is connected to the inlet of the compressor 5 , and the liquid outlet is connected to the inlet of the liquid CO 2 storage tank 1 .

[0006] The water side of the cooling heat exchanger 2 is provided with a first connecting pipe 3A and a second connecting pipe 3B; the water side of the heating heat exchanger 6 is provided with a third connecting pipe 7A and a fourth connecting pipe 7B; When the carbon dioxide energy storage cooling and heating system only provides cooling to the outside, the first connecting pipe 3A is connected to the chilled water return pipe, the second connecting pipe 3B is connected to the chilled water supply pipe, the third connecting pipe 7A is connected to the cooling water inlet pipe, and the fourth connecting pipe 7B is connected to the cooling water outlet pipe; When the carbon dioxide energy storage cooling and heating system only supplies heat to the outside, the first connecting pipe 3A is connected to the normal temperature cold water inlet pipe, the second connecting pipe 3B is connected to the normal temperature cold water outlet pipe, the third connecting pipe 7A is connected to the hot water return pipe, and the fourth connecting pipe 7B is connected to the hot water supply pipe; When the carbon dioxide energy storage cooling and heating system simultaneously supplies cooling and heating to the outside, the first connecting pipe 3A is connected to the chilled water return pipe, the second connecting pipe 3B is connected to the chilled water supply pipe, the third connecting pipe 7A is connected to the hot water return pipe, and the fourth connecting pipe 7B is connected to the hot water supply pipe.

[0007] The compressor 5 is powered by a battery or a power system.

[0008] Power is supplied by batteries during peak hours and by the power system during low hours. In the power flat period, the remaining storage capacity of the battery and the flat electricity price are used to determine whether to supply power from the battery or the power system in order to reduce operating costs.

[0009] The operating pressure range of the cooling heat exchanger 2 is 3.4861Mpa~3.6742Mpa; The maximum working pressure range of the heating heat exchanger 6 is 9Mpa~12Mpa; The maximum working pressure range of the liquid CO2 storage tank 1 is 3.5Mpa~3.7Mpa, and the maximum working pressure range of the gaseous CO2 storage equipment 4 is 3.4MPaMPa~3.6Mpa.

[0010] An operating method of the carbon dioxide energy storage cooling and heating system using off-peak electricity comprises the following steps: Cooling only: When the gaseous CO2 storage device 4 has not reached the maximum storage capacity (with m g represents the mass of gaseous CO2 that can be stored in the gaseous CO2 storage device 4 under the maximum working pressure, then the maximum storage capacity of the gaseous CO2 storage device 4 is 0.95 m g). When the compressor 5, the heating heat exchanger 6 and the pressure reducing valve 8 in the carbon dioxide loop stop running; when cold is needed, the CO2 flowing out of the liquid CO2 storage tank 1 enters the cooling heat exchanger 2, and the liquid CO2 absorbs heat and becomes gaseous. The released cold is absorbed by the chilled water on the water side of the cooling heat exchanger 2, and the chilled water temperature is reduced to the water supply temperature and then transported to the cold user; after the CO2 releases cold and becomes gaseous, it flows out of the cooling heat exchanger 2 and is stored in the gaseous CO2 storage device 4; When the gaseous CO2 storage device 4 has reached the maximum storage capacity and needs to use cold, the CO2 flowing out of the liquid CO2 storage tank 1 enters the cooling heat exchanger 2, the liquid CO2 absorbs heat and becomes gaseous, and the released cold is absorbed by the chilled water on the water side of the cooling heat exchanger 2, and the chilled water temperature is reduced to the water supply temperature and then transported to the cold user; after the CO2 releases cold and becomes gaseous, it flows out of the cooling heat exchanger 2 and enters the gaseous CO2 storage device 4; the compressor 5 converts the gaseous CO2 storage device 4 into gaseous CO2. The gaseous CO2 is compressed to 5Mpa~7Mpa (preferably 6MPa), and then enters the heat supply heat exchanger 6 to be condensed into liquid CO2. The heat released during the condensation process of the heat supply heat exchanger 6 is taken away by the cooling water on its water side; the liquid CO2 coming out of the heat supply heat exchanger 6 is reduced in pressure by the pressure reducing valve 8 and then enters the gas-liquid separator 9. The gaseous CO2 separated by the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid CO2 separated by the gas-liquid separator 9 enters the liquid CO2 storage tank 1; Heat only: When the storage amount in the gaseous CO2 storage device 4 is higher than the minimum limit (using m g Indicates the mass of gaseous CO2 that can be stored in the gaseous CO2 storage device 4 under the maximum working pressure. The minimum limit of the gaseous CO2 storage device 4 is 0.15 m g . ), the cooling heat exchanger 2 stops running; when heating is needed, the compressor 5 compresses the gaseous CO2 from the gaseous CO2 storage device 4 to 9Mpa~12Mpa (preferably 10MPa) to become a supercritical CO2 fluid, and then enters the heating heat exchanger 6 to exchange heat with the hot water on its water side, and heats the hot water to the water supply temperature before delivering it to the heat user; the supercritical CO2 fluid flowing out of the heating heat exchanger 6 is reduced in pressure by the pressure reducing valve 8 and then enters the gas-liquid separator 9, the gaseous CO2 separated by the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid CO2 separated by the gas-liquid separator 9 enters the liquid CO2 storage tank 1 for storage; When the storage volume in the gaseous CO2 storage device 4 is lower than the minimum limit and heat supply is required, the CO2 flowing out of the liquid CO2 storage tank 1 enters the cooling heat exchanger 2, and the liquid CO2 absorbs heat and becomes gaseous, and the released cold energy is taken away by the normal temperature cold water on the water side of the cooling heat exchanger 2; after the CO2 releases cold energy and becomes gaseous, it flows out of the cooling heat exchanger 2 and enters the gaseous CO2 storage device 4; the compressor 5 compresses the gaseous CO2 flowing out of the gaseous CO2 storage device 4 to 9Mpa~12Mpa (preferably 10MPa) to become a supercritical CO2 fluid, and then enters the heating heat exchanger 6 to exchange heat with the hot water on its water side, heats the hot water to the water supply temperature and then delivers it to the heat user; the supercritical CO2 fluid coming out of the heating heat exchanger 6 enters the gas-liquid separator 9 after the pressure is reduced by the pressure reducing valve 8, and the gaseous CO2 separated by the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid CO2 separated by the gas-liquid separator 9 enters the liquid CO2 storage tank 1; Simultaneous cooling and heating: The CO2 flowing out of the liquid CO2 storage tank 1 enters the cooling heat exchanger 2, and the liquid CO2 absorbs heat and becomes gaseous. The released cold is absorbed by the chilled water on the water side of the cooling heat exchanger 2, and the chilled water temperature is reduced to the water supply temperature and then transported to the cold users; after the CO2 releases cold and becomes gaseous, it flows out of the cooling heat exchanger 2 and enters the gaseous CO2 storage device 4; the compressor 5 compresses the gaseous CO2 flowing out of the gaseous CO2 storage device 4 to 9Mpa~12Mpa (preferably 10MPa) to become a supercritical CO2 fluid, and then enters the heating heat exchanger 6 to exchange heat with the hot water on its water side, and heats the hot water to the water supply temperature and then transports it to the heat users; the supercritical CO2 fluid coming out of the heating heat exchanger 6 enters the gas-liquid separator 9 after the pressure is reduced by the pressure reducing valve 8, and the gaseous CO2 separated by the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid CO2 separated by the gas-liquid separator 9 enters the liquid CO2 storage tank 1.

[0011] Nighttime low electricity consumption: In hot summer weather, when cooling is the main purpose or only cooling is needed, the system is operated during the night when electricity is low, so that the liquid CO2 storage tank 1 reaches the maximum storage capacity (using m l It represents the mass of liquid CO2 that can be stored in liquid CO2 storage tank 1 under the maximum working pressure. The maximum storage capacity of liquid CO2 storage tank 1 is 0.95 m l . ).

[0012] In winter, when heating is the main purpose or only heating is needed, the system is operated during the night when electricity is low, so that the gaseous CO2 storage device 6 reaches the maximum storage capacity.

[0013] Fully charge the battery during power outages.

[0014] Compared with the prior art, the present invention has the following advantages and effects: 1. Make full use of the advantages of liquid and supercritical carbon dioxide, such as high density and large storage capacity, to achieve energy storage and flexible supply of cold and heat, and ensure the reliability of the operation of the cooling and heating system.

[0015] 2. It overcomes the shortcomings of existing water storage and ice storage cooling systems, improves the energy efficiency of energy storage cooling and heating systems, reduces their initial investment and operating costs, and improves the economy of the system.

[0016] 3. Make full use of off-peak electricity storage to achieve peak-to-valley shifting of electricity consumption in cooling and heating systems, and improve the energy efficiency and safety of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The composition and flow chart of the carbon dioxide energy storage cooling and heating system that utilizes off-peak electricity. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with specific embodiments. Example

[0019] like Figure 1 As shown, the present invention discloses a carbon dioxide energy storage cooling and heating system using off-peak electricity, including a carbon dioxide loop, a first pipe 3A and a second pipe 3B on the water side of a cooling heat exchanger 2, and a third pipe 7A and a fourth pipe 7B on the water side of a heating heat exchanger 6.

[0020] The carbon dioxide circuit uses carbon dioxide as the working fluid, and stores cold energy from off-peak electricity (or off-peak electricity stored in batteries) in liquid CO2, and releases cold energy by gasifying liquid CO2 to provide cooling for cold users; the compressor compresses gaseous CO2 to supercritical pressure, turning it into a supercritical CO2 fluid with a higher temperature, and then the supercritical CO2 fluid exchanges heat with hot water to provide heating for hot users.

[0021] The carbon dioxide circuit includes a liquid CO2 storage tank 1, a cooling heat exchanger 2, a gaseous CO2 storage device 4, a compressor 5, a heating heat exchanger 6, a pressure reducing valve 8, and a gas-liquid separator 9.

[0022] The outlet of the liquid CO2 storage tank 1 is connected to the CO2 side inlet of the cooling heat exchanger 2, the CO2 side outlet of the cooling heat exchanger 2 is connected to the inlet of the gaseous CO2 storage device 4, the outlet of the gaseous CO2 storage device 4 is connected to the inlet of the compressor 5, the outlet of the compressor 5 is connected to the CO2 side inlet of the heating heat exchanger 6, the CO2 side outlet of the heating heat exchanger 6 is connected to the inlet of the pressure reducing valve 8, the outlet of the pressure reducing valve 8 is connected to the inlet of the gas-liquid separator 9, the gaseous outlet of the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid outlet is connected to the inlet of the liquid CO2 storage tank 1; The water side of the cooling heat exchanger 2 is provided with a first connecting pipe 3A and a second connecting pipe 3B; the water side of the heating heat exchanger 6 is provided with a third connecting pipe 7A and a fourth connecting pipe 7B.

[0023] When the system of the present invention only supplies cooling to the outside, the first connecting pipe 3A is connected to the chilled water return pipe, the second connecting pipe 3B is connected to the chilled water supply pipe, the third connecting pipe 7A is connected to the cooling water inlet pipe, and the fourth connecting pipe 7B is connected to the cooling water outlet pipe; When the system of the present invention only supplies heat to the outside, the first connecting pipe 3A is connected to the normal temperature cold water inlet pipe, the second connecting pipe 3B is connected to the normal temperature cold water outlet pipe, the third connecting pipe 7A is connected to the hot water return pipe, and the fourth connecting pipe 7B is connected to the hot water supply pipe; When the system of the present invention supplies cooling and heating to the outside at the same time, the first pipe 3A is connected to the chilled water return pipe, the second pipe 3B is connected to the chilled water supply pipe, the third pipe 7A is connected to the hot water return pipe, and the fourth pipe 7B is connected to the hot water supply pipe.

[0024] In the present invention, the cooling heat exchanger 2 is a device that releases cold energy by gasifying liquid CO2 and transfers the cold energy to water; its CO2 side inlet is liquid CO2, and its outlet is gaseous CO2, the working pressure is 3.4861MPa, and the corresponding carbon dioxide saturation temperature is 0°C; the water side is room temperature cold water or chilled water of the cooling system.

[0025] In the present invention, the heating heat exchanger 6 is a device that releases heat from supercritical CO2 fluid (heating only or simultaneous cooling and heating conditions) and liquefies gaseous CO2 (cooling only conditions) and transfers heat to water; under heating only or simultaneous cooling and heating conditions, the CO2 side inlet and outlet of the heating heat exchanger 6 are both supercritical CO2 fluid, the working pressure is 10MPa, and the water side is hot water from the heating system; under cooling only conditions, the CO2 side inlet of the heating heat exchanger 6 is gaseous CO2, the outlet is liquid CO2, the working pressure is 6MPa, and the water side is cooling water.

[0026] In the present invention, the liquid CO2 storage tank 1 is used to store liquid CO2, and its maximum working pressure is 3.5 MPa.

[0027] In the present invention, the gaseous CO2 storage device 4 is used to store gaseous CO2, and its maximum working pressure is 3.4 MPa.

[0028] In the present invention, the compressor 5 is used to increase the pressure of the gaseous CO2 flowing out of the gaseous CO2 storage device 4 from 3.4MPa to 6MPa (cooling condition only) or 10MPa (heating condition only or both cooling and heating condition), and transport it to the heating exchanger 6.

[0029] In the present invention, the pressure reducing valve 8 is used to reduce the pressure of liquid CO2 from 6MPa or 10MPa to 3.5MPa.

[0030] The present invention utilizes the carbon dioxide energy storage cooling and heating system with off-peak electricity. The specific operation methods under different operating conditions are as follows: Cooling only: When the gaseous CO2 storage device 4 has not reached the maximum storage capacity, the carbon dioxide loop partially operates, that is, the compressor 5, the heating heat exchanger 6, the pressure reducing valve 8 and the gas-liquid separator 9 do not operate. When cold is needed, the CO2 flowing out of the liquid CO2 storage tank 1 enters the cooling heat exchanger 2, and the liquid CO2 absorbs heat and becomes gaseous. The released cold is absorbed by the chilled water on the water side of the cooling heat exchanger 2, and the chilled water temperature is reduced to the water supply temperature and then transported to the cold users. The first pipe 3A on the water side of the cooling heat exchanger 2 is connected to the chilled water return pipe, and the second pipe 3B is connected to the chilled water supply pipe. After CO2 releases cold and becomes gaseous, it flows out of the cooling heat exchanger 2 and is stored in the gaseous CO2 storage device 4.

[0031] When the gaseous CO2 storage device 4 has reached the maximum storage capacity, the entire carbon dioxide loop is running. When cold is needed, the CO2 flowing out of the liquid CO2 storage tank 1 enters the cooling heat exchanger 2, and the liquid CO2 absorbs heat and becomes gaseous. The released cold is absorbed by the chilled water on the water side of the cooling heat exchanger 2, and the chilled water temperature is reduced to the water supply temperature and then transported to the cold user. The first pipe 3A on the water side of the cooling heat exchanger 2 is connected to the chilled water return pipe, and the second pipe 3B is connected to the chilled water supply pipe. After CO2 releases cold and becomes gaseous, it flows out of the cooling heat exchanger 2 and enters the gaseous CO2 storage device 4. The compressor 5 compresses the gaseous CO2 flowing out of the gaseous CO2 storage device 4 to 6MPa, and then enters the heating heat exchanger 6 to condense into liquid CO2. The heat released during the condensation process of the heating heat exchanger 6 is taken away by the cooling water on its water side. The third pipe 7A on the water side of the heating heat exchanger 6 is connected to the cooling water inlet pipe, and the fourth pipe 7B is connected to the cooling water outlet pipe. The liquid CO2 coming out of the heat supply heat exchanger 6 enters the gas-liquid separator 9 after the pressure is reduced by the pressure reducing valve 8. The gaseous CO2 separated by the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid CO2 separated by the gas-liquid separator 9 enters the liquid CO2 storage tank 1.

[0032] Heat only: When the storage volume in the gaseous CO2 storage device 4 is higher than the minimum limit, the carbon dioxide loop partially operates, wherein the cooling heat exchanger 2 does not operate. When heating is required, the compressor 5 compresses the gaseous CO2 from the gaseous CO2 storage device 4 to 10MPa to become a supercritical CO2 fluid, and then enters the heating heat exchanger 6 to perform heat exchange with the hot water on its water side, and heats the hot water to the water supply temperature before delivering it to the heat user. The third pipe 7A on the water side of the heating heat exchanger 6 is connected to the hot water return pipe, and the fourth pipe 7B is connected to the hot water supply pipe. The supercritical CO2 fluid flowing out of the heating heat exchanger 6 enters the gas-liquid separator 9 after the pressure is reduced by the pressure reducing valve 8. The gaseous CO2 separated by the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid CO2 separated by the gas-liquid separator 9 enters the liquid CO2 storage tank 1 for storage.

[0033] When the storage volume in the gaseous CO2 storage device 4 is lower than the minimum limit, the entire carbon dioxide loop operates. When heat supply is required, the CO2 flowing out of the liquid CO2 storage tank 1 enters the cooling heat exchanger 2, and the liquid CO2 absorbs heat and becomes gaseous. The released cold energy is taken away by the normal temperature cold water on the water side of the cooling heat exchanger 2. The first pipe 3A on the water side of the cooling heat exchanger 2 is connected to the normal temperature cold water inlet pipe, and the second pipe 3B is connected to the normal temperature cold water outlet pipe. After CO2 releases cold energy and becomes gaseous, it flows out of the cooling heat exchanger 2 and enters the gaseous CO2 storage device 4. The compressor 5 compresses the gaseous CO2 flowing out of the gaseous CO2 storage device 4 to 10MPa to become a supercritical CO2 fluid, and then enters the heating heat exchanger 6 to exchange heat with the hot water on its water side, and heats the hot water to the water supply temperature before transporting it to the heat user. The third pipe 7A on the water side of the heating heat exchanger 6 is connected to the hot water return pipe, and the fourth pipe 7B is connected to the hot water supply pipe. The supercritical CO2 fluid coming out of the heat supply heat exchanger 6 enters the gas-liquid separator 9 after the pressure is reduced by the pressure reducing valve 8. The gaseous CO2 separated by the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid CO2 separated by the gas-liquid separator 9 enters the liquid CO2 storage tank 1.

[0034] Simultaneous cooling and heating: The entire carbon dioxide loop is running. The CO2 flowing out of the liquid CO2 storage tank 1 enters the cooling heat exchanger 2, and the liquid CO2 absorbs heat and becomes gaseous. The released cold energy is absorbed by the chilled water on the water side of the cooling heat exchanger 2, and the chilled water temperature is reduced to the water supply temperature before being transported to the cold user. The first pipe 3A on the water side of the cooling heat exchanger 2 is connected to the chilled water return pipe, and the second pipe 3B is connected to the chilled water supply pipe. After CO2 releases cold energy and becomes gaseous, it flows out of the cooling heat exchanger 2 and enters the gaseous CO2 storage device 4. The compressor 5 compresses the gaseous CO2 flowing out of the gaseous CO2 storage device 4 to 10MPa to become a supercritical CO2 fluid, and then enters the heating heat exchanger 6 to perform heat exchange with the hot water on its water side, and heats the hot water to the water supply temperature before being transported to the heat user. The third pipe 7A on the water side of the heating heat exchanger 6 is connected to the hot water return pipe, and the fourth pipe 7B is connected to the hot water supply pipe. The liquid CO2 coming out of the heat supply heat exchanger 6 enters the gas-liquid separator 9 after the pressure is reduced by the pressure reducing valve 8. The gaseous CO2 separated by the gas-liquid separator 9 is connected to the inlet of the compressor 5, and the liquid CO2 separated by the gas-liquid separator 9 enters the liquid CO2 storage tank 1.

[0035] Nighttime low electricity consumption: In hot summer weather, when cooling is the main purpose or only cooling is needed, the system is operated during the night when electricity is low, so that the liquid CO2 storage tank 1 reaches the maximum storage capacity.

[0036] In winter, when heating is the main purpose or only heating is needed, the system is operated during the night when electricity is low, so that the gaseous CO2 storage device 4 reaches the maximum storage capacity.

[0037] Fully charge the battery during power outages.

[0038] The present invention can make full use of off-peak electricity to realize energy storage and flexible supply of cold and heat, and has reliable operation, high energy utilization efficiency and good economy.

[0039] As described above, the present invention can be implemented well.

[0040] The implementation methods of the present invention are not limited to the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A carbon dioxide energy storage cooling and heating system using off-peak electricity, comprising a carbon dioxide circuit, characterized in that: The carbon dioxide circuit comprises a liquid CO2 storage tank (1), a cooling heat exchanger (2), a gaseous CO2 storage device (4), a compressor (5), a heating heat exchanger (6), a pressure reducing valve (8), and a gas-liquid separator (9); The outlet of the liquid CO2 storage tank (1) is connected to the CO2 side inlet of the cooling heat exchanger (2); The CO2 side outlet of the cooling heat exchanger (2) is connected to the inlet of the gaseous CO2 storage device (4); The outlet of the gaseous CO2 storage device (4) is connected to the inlet of the compressor (5); The outlet of the compressor (5) is connected to the CO2 side inlet of the heat supply heat exchanger (6); The CO2 side outlet of the heat supply heat exchanger (6) is connected to the inlet of the pressure reducing valve (8); The outlet of the pressure reducing valve (8) is connected to the inlet of the gas-liquid separator (9); The gaseous outlet of the gas-liquid separator (9) is connected to the inlet of the compressor (5), and the liquid outlet is connected to the inlet of the liquid CO2 storage tank (1).

2. The carbon dioxide energy storage cooling and heating system using off-peak electricity according to claim 1 is characterized in that: The water side of the cooling heat exchanger (2) is provided with a first connecting pipe (3A) and a second connecting pipe (3B); the water side of the heating heat exchanger (6) is provided with a third connecting pipe (7A) and a fourth connecting pipe (7B); When the carbon dioxide energy storage cooling and heating system only provides cooling to the outside, the first connecting pipe (3A) is connected to the chilled water return pipe, the second connecting pipe (3B) is connected to the chilled water supply pipe, the third connecting pipe (7A) is connected to the cooling water inlet pipe, and the fourth connecting pipe (7B) is connected to the cooling water outlet pipe; When the carbon dioxide energy storage cooling and heating system only supplies heat to the outside, the first connecting pipe (3A) is connected to the normal temperature cold water inlet pipe, the second connecting pipe (3B) is connected to the normal temperature cold water outlet pipe, the third connecting pipe (7A) is connected to the hot water return pipe, and the fourth connecting pipe (7B) is connected to the hot water supply pipe; When the carbon dioxide energy storage cooling and heating system simultaneously supplies cooling and heating to the outside, the first connecting pipe (3A) is connected to the chilled water return pipe, the second connecting pipe (3B) is connected to the chilled water supply pipe, the third connecting pipe (7A) is connected to the hot water return pipe, and the fourth connecting pipe (7B) is connected to the hot water supply pipe.

3. The carbon dioxide energy storage cooling and heating system using off-peak electricity according to claim 2 is characterized in that: The compressor (5) is powered by a battery or a power system.

4. The carbon dioxide energy storage cooling and heating system using off-peak electricity according to claim 3 is characterized by: Power is supplied by batteries during peak hours and by the power system during low hours. During power outages, the user can choose to use the battery or the power system for power supply based on the remaining battery power and the power price during the outage.

5. The carbon dioxide energy storage cooling and heating system using off-peak electricity according to claim 1 is characterized in that: The operating pressure range of the cooling heat exchanger (2) is 3.4861 MPa to 3.6742 MPa; The maximum operating pressure range of the heating heat exchanger (6) is 9Mpa~12Mpa; The maximum working pressure range of the liquid CO2 storage tank (1) is 3.5 MPa to 3.7 MPa, and the maximum working pressure range of the gaseous CO2 storage device (4) is 3.4 MPa to 3.6 MPa.

6. An operating method of a carbon dioxide energy storage cooling and heating system utilizing off-peak electricity as claimed in any one of claims 1 to 5, characterized in that include: Cooling only: When the gaseous CO2 storage device (4) has not reached the maximum storage capacity, the compressor (5), the heating heat exchanger (6) and the pressure reducing valve (9) in the carbon dioxide loop stop running; when cold is needed, the CO2 flowing out of the liquid CO2 storage tank (1) enters the cooling heat exchanger (2), the liquid CO2 absorbs heat and becomes gaseous, and the released cold is absorbed by the chilled water on the water side of the cooling heat exchanger (2), and the chilled water temperature is reduced to the water supply temperature before being transported to the cold user; after the CO2 releases cold and becomes gaseous, it flows out of the cooling heat exchanger (2) and is stored in the gaseous CO2 storage device (4); When the gaseous CO2 storage device (4) has reached its maximum storage capacity and needs to use cold, the CO2 flowing out of the liquid CO2 storage tank (1) enters the cold supply heat exchanger (2), the liquid CO2 absorbs heat and becomes gaseous, and the released cold is absorbed by the chilled water on the water side of the cold supply heat exchanger (2), the chilled water temperature is lowered to the water supply temperature and then transported to the cold user; after the CO2 releases cold and becomes gaseous, it flows out of the cold supply heat exchanger (2) and enters the gaseous CO2 storage device (4); the compressor (5) converts the gaseous CO2 storage device (4) into a gaseous CO2. ) The gaseous CO2 flowing out is compressed to 5Mpa~7Mpa, and then enters the heat supply heat exchanger (6) to be condensed into liquid CO2. The heat released during the condensation process of the heat supply heat exchanger (6) is taken away by the cooling water on its water side. The liquid CO2 coming out of the heat supply heat exchanger (6) is reduced in pressure by the pressure reducing valve (8) and then enters the gas-liquid separator (9). The gaseous CO2 separated by the gas-liquid separator (9) is connected to the inlet of the compressor (5). The liquid CO2 separated by the gas-liquid separator (9) enters the liquid CO2 storage tank (1); Heat only: When the storage volume in the gaseous CO2 storage device (4) is higher than the minimum limit, the cooling heat exchanger (2) stops running; when heating is required, the compressor (5) compresses the gaseous CO2 from the gaseous CO2 storage device (4) to 9Mpa~12Mpa to convert it into a supercritical CO2 fluid, which then enters the heating heat exchanger (6) to perform heat exchange with the hot water on its water side, heats the hot water to the water supply temperature, and then delivers it to the heat user; the supercritical CO2 fluid flowing out of the heating heat exchanger (6) is reduced in pressure by the pressure reducing valve (8) and then enters the gas-liquid separator (9), the gaseous CO2 separated by the gas-liquid separator (9) is connected to the inlet of the compressor (5), and the liquid CO2 separated by the gas-liquid separator (9) enters the liquid CO2 storage tank (1) for storage; When the storage volume in the gaseous CO2 storage device (4) is lower than the minimum limit and heat supply is required, the CO2 flowing out of the liquid CO2 storage tank (1) enters the cooling heat exchanger (2), and the liquid CO2 absorbs heat and becomes gaseous. The released cold energy is taken away by the normal temperature cold water on the water side of the cooling heat exchanger (2); after the CO2 releases cold energy and becomes gaseous, it flows out of the cooling heat exchanger (2) and enters the gaseous CO2 storage device (4); the compressor (5) compresses the gaseous CO2 flowing out of the gaseous CO2 storage device (4) to 9Mpa~12Mpa to become supercritical CO2 fluid, and then enter the heat supply heat exchanger (6) to exchange heat with hot water on the water side, and heat the hot water to the water supply temperature before being transported to the heat user; the supercritical CO2 fluid coming out of the heat supply heat exchanger (6) is reduced in pressure by the pressure reducing valve (8) and then enters the gas-liquid separator (9), the gaseous CO2 separated by the gas-liquid separator (9) is connected to the inlet of the compressor (5), and the liquid CO2 separated by the gas-liquid separator (9) enters the liquid CO2 storage tank (1); Simultaneous cooling and heating: The CO2 flowing out of the liquid CO2 storage tank (1) enters the cooling heat exchanger (2), where the liquid CO2 absorbs heat and becomes gaseous. The released cold energy is absorbed by the chilled water on the water side of the cooling heat exchanger (2), and the chilled water temperature is lowered to the water supply temperature before being transported to the cold users. After the CO2 releases the cold energy and becomes gaseous, it flows out of the cooling heat exchanger (2) and enters the gaseous CO2 storage device (4). The compressor (5) compresses the gaseous CO2 flowing out of the gaseous CO2 storage device (4) to 9 Mpa~1 2Mpa becomes a supercritical CO2 fluid, and then enters the heat supply heat exchanger (6) to exchange heat with the hot water on the water side, and the hot water is heated to the water supply temperature and then transported to the heat user; the supercritical CO2 fluid coming out of the heat supply heat exchanger (6) is reduced in pressure by the pressure reducing valve (10), and then enters the gas-liquid separator (9), the gaseous CO2 separated by the gas-liquid separator (9) is connected to the inlet of the compressor (5), and the liquid CO2 separated by the gas-liquid separator (9) enters the liquid CO2 storage tank (1).

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