CN115682456B - Data center waste heat recovery-oriented CO 2 Heat pump energy storage method - Google Patents

Abstract

The invention discloses a CO for data center waste heat recovery ₂ The heat pump energy storage method adopts a chilled water loop comprising a data center and CO ₂ Heat pump cycle, CO ₂ An energy storage system for storing energy and circulating water; chilled Water passage through CO ₂ The heat pump is cooled in a circulating way and is cooled by the air blowing of a fan; CO ₂ Heat pump cycle and CO ₂ Energy storage and circulating coupling; during the electricity consumption low valley period, CO ₂ Low pressure CO in a heat pump cycle ₂ CO in a storage tank ₂ Circularly absorbing the residual heat of the chilled water loop, compressing the residual heat by a refrigeration compressor, and then entering CO ₂ The energy storage compressor of the energy storage cycle compresses again and stores the compressed energy in the high-pressure CO after cooling ₂ In the storage tank; at peak period of electricity consumption, CO ₂ The heat pump cycle normally operates to absorb the residual heat of the chilled water loop and high-pressure CO ₂ CO in a storage tank ₂ After absorbing heat, the output enters an expansion machine to do work, and the CO is driven preferentially ₂ The heat pump cycle generates heat while outputting cold energy to the data center; under the normal state, CO ₂ The heat pump cycle may be independent of CO ₂ The energy storage circulation independently operates, so that the waste heat of the chilled water loop can be stably absorbed, and the stable supply of the cold energy of the data center is ensured.

Description

A CO2 heat pump energy storage method for waste heat recovery in data centers

Technical Field

The present invention relates to the application fields of waste heat utilization of data centers and _CO2 heat pump and energy storage technology, and in particular to a _CO2 heat pump energy storage method for waste heat recovery in data centers.

Background technique

At present, mankind is entering the digital economy era. As an important carrier of infrastructure in the digital economy era, the stable operation of data centers requires huge amounts of electricity and cooling energy, which not only has high operating costs, but also places relatively high pressure on carbon emission reduction. Therefore, based on the energy consumption characteristics of data centers, how to reduce costs and increase efficiency and connect to renewable energy power generation systems to reduce carbon emissions is a difficult problem that the energy industry needs to solve urgently.

To ensure the safe and reliable operation of IT equipment, the power of data centers is mainly used for servers, air conditioning, UPS and lighting. Because the heat generated by IT equipment is discharged to the environment, the power consumption of air conditioning accounts for a very high proportion, resulting in low energy efficiency of data centers.

In addition, as large electricity consumers, data centers need to operate 24 hours a day, which makes electricity costs high during peak hours. It also makes it difficult for renewable energy sources such as solar and wind energy to directly power data centers.

Summary of the invention

The purpose of the present invention is to provide a _CO2 heat pump energy storage method for data center waste heat recovery, which can maximize energy utilization and reduce system operating costs.

The _CO2 heat pump energy storage method for waste heat recovery in a data center provided by the present invention adopts an energy storage system including a chilled water loop in a data center, a _CO2 heat pump cycle, a _CO2 energy storage cycle and a circulating water loop; while the chilled water in the chilled water loop in the data center is cooled by the _CO2 heat pump cycle, a natural cold source is introduced and cooled by fan blowing; the _CO2 heat pump cycle is coupled with the _CO2 energy storage cycle; during the off-peak period of electricity consumption, the _CO2 cycle in the low-pressure _CO2 storage tank in the _CO2 heat pump cycle absorbs the waste heat of the chilled water loop in the data center, enters the energy storage compressor of the _CO2 energy storage cycle after being compressed by the refrigeration compressor, is compressed again and cooled, and finally stored in the high-pressure _CO2 storage tank; during the peak period of electricity consumption, the _CO2 heat pump cycle operates normally to absorb the waste heat of the chilled water loop in the data center, and at the same time, the _CO2 output in the high-pressure _CO2 storage tank enters the expander to do work after absorbing heat and heating, and preferentially drives the _CO2 heat pump cycle to output cooling capacity for the data center while generating heat; under normal conditions, the _CO2 heat pump cycle can be independent of the CO ₂ The energy storage cycle operates independently, stably absorbing the waste heat of the data center's chilled water circuit to ensure a stable supply of cooling capacity in the data center.

In one embodiment of the above method, a heat exchanger A (2) and a heat exchanger B (6) connected in parallel are provided in the chilled water circuit of the data center, the heat exchange medium of the heat exchanger A (2) is chilled water and air, and the heat exchange medium of the heat exchanger B (6) is chilled water and _CO2 in a _CO2 heat pump cycle.

In one embodiment of the above method, the equipment in the _CO2 heat pump cycle includes the low-pressure _CO2 storage tank (12) and the refrigeration compressor (7), and also includes a cooler A (9) and a cold water heat exchanger (10); the _CO2 in the low-pressure _CO2 storage tank (12) absorbs heat from the heat exchanger B (6) and enters the refrigeration compressor (7) for compression, and the compressed _CO2 is divided into two paths, one of which flows back to the low-pressure _CO2 storage tank (12) after passing through the cooler A (9) and the cold water heat exchanger (10) to continue the next cycle, and the other enters the _CO2 energy storage cycle.

In a second embodiment of the above method, a regenerator (24) is further provided in the _CO2 heat pump cycle, and the _CO2 in the low-pressure _CO2 storage tank (12) flows through the regenerator (24) and then enters the heat exchanger B (6) to absorb heat, and then flows through the regenerator (24) and then enters the refrigeration compressor (7) to be compressed and then divided into two paths.

In a third embodiment of the above method, the CO ₂ compressed by the refrigeration compressor (7) in the CO ₂ heat pump cycle is first cooled by a cooler A (9) and then divided into two paths.

In the three implementation modes of the above method, the _CO2 energy storage cycle is provided with an energy storage compressor (17), a cooler B (18), a high-pressure _CO2 storage tank (19), a heater (20) and an expander (21); the energy storage compressor (17) re-compresses the CO2 output by the refrigeration compressor (7), and stores the _CO2 in the high-pressure _CO2 storage tank (19) after cooling by the cooler B (18); when releasing energy, the _CO2 in the high-pressure _CO2 storage tank (19) is heated by the heater (20) and enters the expander (21) to perform work, and then enters the cold water heat exchanger (10) of the _CO2 heat pump cycle to be cooled and then divided into two paths, one path enters the heat exchanger B (6) to absorb heat, and the other path flows into the low-pressure _CO2 storage tank (12).

In the three implementation modes of the above method, a cold water tank (22) and a hot water tank (23) are provided in the circulating water loop. The cold water in the cold water tank (22) enters the cooler B (18) to absorb the heat of _CO2 and then flows into the hot water tank (23). The hot water in the hot water tank (23) flows through the heater (20) to provide heat for _CO2 and then flows into the cold water tank (22) for circulation.

In a fourth embodiment of the above method, the _CO2 energy storage cycle is provided with a primary compressor (25), a primary intercooler (26), a secondary compressor (27), a secondary intercooler (28), a primary reheater (29), a primary expander (30), a secondary reheater (31), a secondary expander (32), a flow divider (33), a flow mixer (34), a flow divider (35), and a flow mixer (36); the _CO2 compressed by the refrigeration compressor (7) enters the primary compressor (25) and releases heat after being compressed in the primary intercooler (26), and then enters the secondary intercooler (28) after being compressed in the secondary compressor (27) and is stored in the high-pressure _CO2 storage tank (19) after being released heat; when releasing energy, the CO2 in the high-pressure _CO2 storage tank (19) ₂ passes through the primary reheater (29), the primary expander (30), the secondary reheater (31) and the secondary expander (32) in sequence, and then enters the cold water heat exchanger (10) for cooling, and then is divided into two paths, one of which enters the heat exchanger B (6) to absorb heat, and the other flows into the low-pressure _CO2 storage tank (12).

In a fourth embodiment of the above method, a cold water tank (22) and a hot water tank (23) are provided in the circulating water loop, and the cold water in the cold water tank (22) is divided into two paths through a flow divider (33), one path entering the primary intercooler (26) to absorb heat from _CO2 , and the other path entering the secondary intercooler (28) to absorb heat from _CO2 , and the hot water at the outlets of the primary intercooler (26) and the secondary intercooler (28) is mixed through a flow mixer (34) and then flows into the hot water tank (23); the hot water in the hot water tank (23) is divided into two paths through a flow divider (35), the other path entering the primary reheater (29) to provide heat for _CO2 , and the other path entering the secondary reheater (31) to provide heat for _CO2 , and the cold water at the outlets of the primary reheater (29) and the secondary reheater (31) flows into the cold water tank (22) after passing through the flow mixer (36).

In the four implementation modes of the above method, the various devices of the system are connected by pipelines, regulating valves are respectively arranged on the two branches of the data center's chilled water loop, regulating valves and throttle valves are respectively arranged on the pipeline of the _CO2 heat pump circulation, and regulating valves are respectively arranged on the two branches after the refrigeration compressor.

The present invention couples _CO2 heat pump with energy storage and applies it to data centers, which can not only realize efficient cooling of data centers, but also make full use of waste heat of heat pumps, and promote efficient use of renewable energy in data centers, thereby maximizing energy utilization and reducing system operating costs. Specifically, the present invention has the following advantages: 1) The heat pump cooling technology is adopted, which can not only realize cooling of data centers, but also increase the waste heat temperature of data centers, realize heat supply, and thus improve energy utilization and system power generation efficiency. 2) The natural working fluid _CO2 is adopted, which has good heat transfer capacity and is pollution-free and non-destructive to the environment, and can meet the system's cost reduction, efficiency improvement, green and low-carbon needs. 3) While using heat pump cooling, the data center introduces a natural cold source, further reducing cooling energy consumption. 4) Energy storage is applied to data centers, which can be used as a backup power supply for data centers, while promoting efficient use of renewable energy in data centers, ensuring the stable output of renewable energy power, and optimizing energy use structure. 5) Under the huge difference in peak and valley electricity prices, the present invention adopts _CO2 energy storage technology to realize the time and space transfer of low-priced electricity, effectively reducing the difference in peak and valley electricity consumption. 6) Coupling _CO2 heat pumps with energy storage can not only efficiently realize the cooling of data centers, make full use of the waste heat of heat pumps, improve the efficiency of power storage, but also significantly reduce the operating costs of the system. 7) The _CO2 heat pump and energy storage cycle can introduce a variety of thermal processes, such as heat recovery, reheating, and recompression. The structure layout is flexible and can further improve the power generation efficiency of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of system connection according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of system connection according to a second embodiment of the present invention.

FIG3 is a schematic diagram of system connection according to Embodiment 3 of the present invention.

FIG. 4 is a schematic diagram of system connection according to a fourth embodiment of the present invention.

Serial number in the picture:

1-Data center; 2-Heat exchanger A; 3-Fan; 4-Valve; 5-Valve; 6-Heat exchanger B; 7-Refrigeration compressor;

8-valve; 9-cooler A; 10-cold water heat exchanger; 11-valve; 12-low-pressure _CO2 storage tank; 13-valve;

14-valve; 15-throttle valve; 16-valve; 17-energy storage compressor; 18-cooler B;

19-high pressure _CO2 storage tank; 20-heater; 21-expander, 22-cold water tank, 23-hot water tank;

24-regenerator;

25-first stage compressor; 26-first stage intercooler; 27-second stage compressor; 28-second stage intercooler;

29-first-stage reheater; 30-first-stage expander; 31-second-stage reheater; 32-second-stage expander;

33- flow divider; 34- flow mixer; 35- flow divider; 36- flow mixer.

Detailed ways

The _CO2 heat pump energy storage method for waste heat recovery in a data center disclosed in the present invention adopts a system energy storage including a chilled water circuit of a data center, a _CO2 heat pump cycle, a _CO2 energy storage cycle and a circulating water circuit. Specifically, while the chilled water in the chilled water circuit of the data center is cooled by the _CO2 heat pump cycle, a natural cold source is introduced and cooled by fan blowing. The _CO2 heat pump cycle is coupled with the _CO2 energy storage cycle. During the off-peak period of electricity consumption, the _CO2 in the low-pressure _CO2 storage tank in the CO2 heat pump cycle absorbs the waste _heat of the chilled water circuit of the data center, and then directly enters the energy storage compressor of the _CO2 energy storage cycle through the refrigeration compressor to be compressed again and stored in the high-pressure _CO2 storage tank. During the peak period of electricity consumption, the _CO2 heat pump cycle operates normally to absorb the waste heat of the chilled water circuit of the data center. At the same time, the _CO2 in the high-pressure _CO2 storage tank enters the expander to do work after absorbing heat and heating up, and preferentially drives the _CO2 heat pump cycle to output cooling capacity for the data center while generating heat. Under normal conditions, the _CO2 heat pump cycle can also be independent of the CO2 heat pump cycle. ₂ The energy storage cycle operates independently, which can stably absorb the waste heat of the data center's chilled water circuit and ensure a stable supply of cooling capacity in the data center.

The specific application of the present invention is described in detail below through four embodiments.

Example

As shown in FIG1 , in this embodiment, the chilled water of the data center's chilled water loop flows through the data center 1 to absorb its heat, and the outlet main is divided into two branches. The water flow rates of the two branches are controlled by valves 4 and 5, respectively. One branch passes through valve 4 and enters the heat exchanger A2 to exchange heat with the natural cold source introduced by the fan 3 through blowing for cooling, and the other branch passes through valve 5 and enters the heat exchanger B6 to release heat and cool. The chilled water flowing out of the heat exchanger A2 and the heat exchanger B6 are mixed and flow into the data center 1, completing a chilled water cycle.

The equipment arranged in the _CO2 heat pump cycle includes a low-pressure _CO2 storage tank 12, a refrigeration compressor 7, a cooler A9 and a cold water heat exchanger 10.

The equipment installed in the _CO2 energy storage cycle includes energy storage compressor 17, cooler B18, high-pressure _CO2 storage tank 19, heater 20, and expander 21.

The equipment provided in the circulating water loop includes a cold water tank 22 and a hot water tank 23 .

During the period of low electricity consumption, energy is stored through the _CO2 heat pump cycle: the _CO2 in the low-pressure _CO2 storage tank 12 enters the throttle valve 15 for throttling after the flow is controlled by valve 13, and the _CO2 flowing out of the throttle valve 15 enters the heat exchanger B6 to absorb heat and then enters the refrigeration compressor 7 for compression. The compressed _CO2 is divided into two outputs: one path flows through valve 8, cooler A9, and cold water heat exchanger 10 and then flows back to the low-pressure _CO2 storage tank 12, and then enters the next cycle; the other path passes through valve 16 and enters the energy storage compressor 17 for compression again, and then releases heat through cooler B18 and is stored in the high-pressure _CO2 storage tank 19.

When releasing energy during peak electricity consumption, the _CO2 in the high-pressure _CO2 storage tank 19 enters the heater 20 to absorb heat, then expands and does work through the expander 21 and enters the cold water heat exchanger 10 for cooling. The cooled _CO2 is divided into two output paths. The first path passes through valves 14 and 15 and enters the heat exchanger B6 for the heat absorption cycle to ensure the normal operation of the heat pump cycle. The second path passes through valve 11 and flows into the low-pressure _CO2 storage tank 12. The output of the first path is preferred, and the excess _CO2 flows into the low-pressure _CO2 storage tank 12.

Under normal conditions, valve 16 and valve 11 can be closed to run the _CO2 heat pump cycle alone: the _CO2 in the low-pressure _CO2 storage tank 12 enters the throttle valve 15 for throttling after the flow is controlled by valve 13, the _CO2 flowing out of the throttle valve 15 enters the heat exchanger B6 to absorb heat and then enters the refrigeration compressor 7 for compression, the compressed _CO2 flows through valve 8, cooler A9, and cold water heat exchanger 10 and then flows back to the low-pressure _CO2 storage tank 12, and then enters the next cycle.

During the energy storage and release process, the cold water in the cold water tank 22 enters the cooler B18 to absorb the heat _{of CO2} and then flows into the hot water tank 23; the hot water in the hot water tank 23 flows through the heater 20 to provide heat for the _CO2 in the heater 20, and then flows into the cold water tank 22.

The cooling water flowing through the cooler A9 absorbs heat and can provide heat according to actual needs.

Example

The difference between this embodiment and the first embodiment is that a regenerator 24 is added to the _CO2 heat pump cycle, and the _CO2 output from the low-pressure _CO2 storage tank first flows through the regenerator 24 and then enters the heat exchanger B6 of the chilled water circuit. The _CO2 coming out of the heat exchanger B6 flows through the regenerator 24 again and then enters the refrigeration compressor 7 for compression.

In the _CO2 heat pump cycle, the temperature of _CO2 flowing into the throttle valve 15 is still very high. Adding a regenerator can reduce the temperature of _CO2 flowing into the throttle valve 15, recover part of the waste heat that would have been discharged into the environment, and improve the cycle efficiency.

The rest of this embodiment is the same as the first embodiment.

Example

The difference between this embodiment and the first embodiment is that the CO ₂ compressed by the refrigeration compressor 7 is first cooled by the cooler A9 and then output in two ways.

During the energy storage process, the temperature of _CO2 compressed by the refrigeration compressor 7 decreases after cooling, and the density increases. It is then compressed by the energy storage compressor 17, which can effectively reduce the power consumption of compression and improve the system efficiency. In addition, after the cooling water absorbs the heat of _CO2 , it can provide heat according to actual needs and perform heat exchange at the main pipe. The cooling water can absorb more heat, improve the heating capacity, and thus increase the system efficiency.

The rest of this embodiment is the same as the first embodiment.

Example

The difference between this embodiment and the first embodiment is that the equipment arranged in the _CO2 energy storage cycle includes a primary compressor 25, a primary intercooler 26, a secondary compressor 27, a secondary intercooler 28, a primary reheater 29, a primary expander 30, a secondary reheater 31, a secondary expander 32, a splitter 33, a mixer 34, a splitter 35 and a mixer 36.

During the energy storage process, the _CO2 compressed by the refrigeration compressor 7 enters the first-stage compressor 25 for compression through the valve 16, then releases heat through the first-stage intercooler 26, and then enters the second-stage compressor 27 for compression again, and then releases heat again through the second-stage intercooler 28 before being stored in the high-pressure _CO2 storage tank 19; during the energy release process, the _CO2 in the high-pressure _CO2 storage tank 19 successively passes through the first-stage reheater 29, the first-stage expander 30, the second-stage reheater 31 and the second-stage expander 32 to absorb heat-expand-absorb heat again-expand again, and then enters the cold water heat exchanger 10 for cooling, and then flows into the low-pressure _CO2 storage tank 12 through the valve 11.

The cold water in the cold water tank 22 in the circulating water loop is split by the splitter 33, one way enters the primary intercooler 26 to absorb the heat of _CO2 , and the other way enters the secondary intercooler 28 to absorb the heat _{of CO2} . The hot water at the outlets of the primary intercooler 26 and the secondary intercooler 28 are mixed by the mixer 34 and flow into the hot water tank 23; the hot water in the hot water tank 23 is split by the splitter 35, one way enters the primary reheater 29 to provide heat for _CO2 , and the other way enters the secondary reheater 31 to provide heat for _CO2 . The cold water at the outlets of the primary reheater 29 and the secondary reheater 31 are mixed by the mixer 36 and flow into the cold water tank 22.

By adopting staged compression and interstage cooling, the temperature of _CO2 after primary compression can be reduced, the density can be increased, and secondary compression can be performed more easily, thereby reducing the system compression power consumption. Similarly, by adopting staged expansion and interstage reheating, the system expansion work capacity can be improved. The combination of staged compression and staged expansion can effectively improve the system output power and increase the system benefits.

The rest of this embodiment is the same as the first embodiment.

It can be seen from the above four embodiments of the present invention that the present invention has the following advantages:

(1) The use of heat pump cooling technology can not only cool the data center, but also increase the waste heat temperature of the data center to achieve heat supply, thereby improving energy utilization and system power generation efficiency.

(2) The natural working fluid CO ₂ is used, which has good heat transfer capacity and is non-polluting and non-destructive to the environment, and can meet the system's needs for cost reduction, efficiency improvement, and green and low-carbon development.

(3) While using heat pumps for cooling, the data center also introduced natural cooling sources to further reduce cooling energy consumption.

(4) Applying energy storage to data centers can serve as a backup power source for data centers. At the same time, it can promote the efficient use of renewable energy in data centers, ensure the stable output of renewable energy electricity, and optimize the energy consumption structure.

(5) Under the huge difference between peak and valley electricity prices, the use of _CO2 energy storage technology realizes the temporal and spatial transfer of low-cost electricity, effectively reducing the difference in peak and valley electricity consumption.

(6) Coupling the _CO2 heat pump with energy storage can not only efficiently achieve cooling of the data center, make full use of the waste heat of the heat pump, improve the efficiency of power storage, but also significantly reduce the operating costs of the system.

(7) The _CO2 heat pump and energy storage cycle can introduce a variety of thermal processes, such as heat recovery, reheating, and recompression. The structural layout is flexible and can further improve the power generation efficiency of the system.

Claims (10)

1. A _CO2 heat pump energy storage method for waste heat recovery in a data center, characterized in that: the method adopts an energy storage system including a data center chilled water loop, a _CO2 heat pump cycle, a _CO2 energy storage cycle and a circulating water loop; The chilled water in the data center's chilled water loop is cooled by the _CO2 heat pump cycle while introducing a natural cold source and using fans to blow air for cooling; the _CO2 heat pump cycle is coupled with the _CO2 energy storage cycle; During the off-peak period of electricity consumption, the _CO2 cycle in the low-pressure _CO2 storage tank in the _CO2 heat pump cycle absorbs the waste heat from the data center's chilled water circuit, which is compressed by the refrigeration compressor and then enters the _CO2 energy storage compressor in the CO2 energy storage cycle to be compressed and cooled again, and finally stored in the high-pressure _CO2 storage tank; During peak electricity consumption, the _CO2 heat pump cycle operates normally to absorb the waste heat of the data center's chilled water circuit. At the same time, the _CO2 output in the high-pressure _CO2 storage tank enters the expander to do work after absorbing heat and heating up, and preferentially drives the _CO2 heat pump cycle to output cooling to the data center while generating heat. Under normal conditions, the _CO2 heat pump cycle can operate independently of the _CO2 energy storage cycle, stably absorbing the waste heat from the data center's chilled water circuit and ensuring a stable supply of cooling in the data center. 2. The method according to claim 1, characterized in that: a heat exchanger A (2) and a heat exchanger B (6) are provided in parallel in the chilled water circuit of the data center, the heat exchange medium of the heat exchanger A (2) is chilled water and air, and the heat exchange medium of the heat exchanger B (6) is chilled water and _CO2 in a _CO2 heat pump cycle. 3. The method according to claim 2, characterized in that: the equipment in the _CO2 heat pump cycle includes the low-pressure _CO2 storage tank (12) and the refrigeration compressor (7), and also includes a cooler A (9) and a cold water heat exchanger (10); the _CO2 in the low-pressure _CO2 storage tank (12) absorbs heat from the heat exchanger B (6) and enters the refrigeration compressor (7) for compression, and the compressed _CO2 is divided into two paths, one path passes through the cooler A (9) and the cold water heat exchanger (10) and then flows back to the low-pressure _CO2 storage tank (12) to continue the next cycle, and the other path enters the _CO2 energy storage cycle. 4. The method according to claim 3 is characterized in that: a regenerator (24) is also provided in the _CO2 heat pump cycle, and the _CO2 in the low-pressure _CO2 storage tank (12) flows through the regenerator (24) and then enters the heat exchanger B (6) to absorb heat, and then flows through the regenerator (24) and then enters the refrigeration compressor (7) to be compressed and then divided into two paths. 5. The method according to claim 3, characterized in that: the _CO2 compressed by the refrigeration compressor (7) in the _CO2 heat pump cycle is first cooled by a cooler A (9) and then divided into two paths. 6. The method according to any one of claims 3 to 5, characterized in that: the _CO2 energy storage cycle is provided with an energy storage compressor (17), a cooler B (18), a high-pressure _CO2 storage tank (19), a heater (20) and an expander (21); the energy storage compressor (17) re-compresses the _CO2 output by the refrigeration compressor (7), and stores it in the high-pressure _CO2 storage tank (19) after cooling by the cooler B (18); when releasing energy, _{the CO2} in the high-pressure CO2 storage tank (19) is heated by the heater (20) and enters the expander (21) to perform work, and then enters the cold water heat exchanger (10) of the _CO2 heat pump cycle to be cooled and then divided into two paths, one path enters the heat exchanger B (6) to absorb heat, and the other path flows into the low-pressure _CO2 storage tank (12). 7. The method according to any one of claims 3 to 5, characterized in that: a cold water tank (22) and a hot water tank (23) are arranged in the circulating water loop, the cold water in the cold water tank (22) enters the cooler B (18) to absorb the heat of _CO2 and then flows into the hot water tank (23), the hot water in the hot water tank (23) flows through the heater (20) to provide heat for _CO2 and then flows into the cold water tank (22) for circulation. 8. The method according to claim 3, characterized in that: the _CO2 energy storage cycle is provided with a primary compressor (25), a primary intercooler (26), a secondary compressor (27), a secondary intercooler (28), a primary reheater (29), a primary expander (30), a secondary reheater (31), a secondary expander (32), a flow divider (33), a flow mixer (34), a flow divider (35), and a flow mixer (36); the _CO2 compressed by the refrigeration compressor (7) enters the primary compressor (25), is compressed and then released through the primary intercooler (26), is compressed again through the secondary compressor (27), enters the secondary intercooler (28), releases heat, and is then stored in the high-pressure _CO2 storage tank (19); when releasing energy, the CO2 in the high-pressure _CO2 storage tank (19) ₂ passes through the primary reheater (29), the primary expander (30), the secondary reheater (31) and the secondary expander (32) in sequence, and then enters the cold water heat exchanger (10) for cooling, and then is divided into two paths, one of which enters the heat exchanger B (6) to absorb heat, and the other flows into the low-pressure _CO2 storage tank (12). 9. The method according to claim 8, characterized in that: a cold water tank (22) and a hot water tank (23) are arranged in the circulating water loop, the cold water in the cold water tank (22) is divided into two paths through a flow divider (33), one path enters the primary intercooler (26) to absorb the heat of _CO2 , and the other path enters the secondary intercooler (28) to absorb the heat of _CO2 , the hot water at the outlets of the primary intercooler (26) and the secondary intercooler (28) is mixed through a flow mixer (34) and then flows into the hot water tank (23); the hot water in the hot water tank (23) is divided into two paths through a flow divider (35), the other path enters the primary reheater (29) to provide heat for _CO2 , and the other path enters the secondary reheater (31) to provide heat for _CO2 , the cold water at the outlets of the primary reheater (29) and the secondary reheater (31) flows into the cold water tank (22) after passing through the flow mixer (36). 10. The method as claimed in claim 3 is characterized in that: the various devices in the system are connected by pipelines, regulating valves are respectively provided on the two branches of the chilled water loop of the data center, regulating valves and throttle valves are provided on the pipeline of the _CO2 heat pump circulation, and regulating valves are respectively provided on the two branches after the refrigeration compressor.