Carbon dioxide refrigeration and temperature control system and method for data center

Abstract

The invention discloses a carbon dioxide refrigeration and temperature control system and method for a data center, and the system comprises a compressor, a condenser, a first underground cavity, an expansion valve, a second underground cavity, an evaporator and a third underground cavity which are sequentially connected in a closed loop manner, liquid carbon dioxide is stored in the first underground cavity, gas-liquid mixed carbon dioxide is stored in the second underground cavity, and low-pressure carbon dioxide gas and heat-exchanged carbon dioxide gas are stored in the third underground cavity. The method comprises the following steps: step 1, carbon dioxide refrigeration of the data center; and 2, controlling the temperature of the data center. The system is reasonable in design, carbon dioxide is effectively utilized to conduct heat exchange refrigeration on the data center, the carbon dioxide after heat exchange is recycled, efficient refrigeration of the data center can be achieved, and energy consumption of the carbon dioxide can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of data center refrigeration, and in particular relates to a carbon dioxide refrigeration and temperature control system for a data center. Background Art

[0002] With the development of modern information technology, the scale and number of data centers have increased significantly. However, the cooling demand of data centers is increasing day by day. Traditional refrigeration systems are difficult to meet the current needs due to low efficiency, high energy consumption and environmental damage of the refrigerants used. In particular, traditional refrigerants such as Freon, although they perform well in refrigeration efficiency, are extremely destructive to the environment and seriously affect global warming. Therefore, seeking an efficient, environmentally friendly and intelligent refrigeration technology has become the focus of current research.

[0003] As a natural refrigerant, carbon dioxide is non-toxic, non-corrosive and has good phase change heat transfer properties, showing broad prospects in refrigeration applications. However, there are still many technical challenges to be solved in how to efficiently apply carbon dioxide refrigeration systems in large data centers, especially in terms of combining intelligent control and renewable energy integration.

[0004] Therefore, a rationally designed carbon dioxide refrigeration and temperature control system for data centers is needed to effectively utilize carbon dioxide for heat exchange and refrigeration of data centers, and to recycle the carbon dioxide after heat exchange, so as to achieve efficient refrigeration of data centers and reduce carbon dioxide energy consumption. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a carbon dioxide refrigeration and temperature control system for a data center in view of the deficiencies in the above-mentioned prior art. The carbon dioxide is reasonably designed and effectively utilizes carbon dioxide for heat exchange and refrigeration of the data center. The carbon dioxide after heat exchange is recycled, which can not only achieve efficient refrigeration of the data center, but also reduce carbon dioxide energy consumption.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a carbon dioxide refrigeration and temperature control system for a data center, characterized in that it includes a compressor 1, a condenser 2, a first underground cavity 3, an expansion valve 4, a second underground cavity 5, an evaporator 6 and a third underground cavity 7 which are connected in a closed loop in sequence, the third underground cavity 7 is connected to the compressor 1, liquid carbon dioxide is stored in the first underground cavity 3, gas-liquid mixed carbon dioxide is stored in the second underground cavity 5, and low-pressure carbon dioxide gas and carbon dioxide gas after heat exchange are stored in the third underground cavity 7.

[0007] The above-mentioned carbon dioxide refrigeration and temperature control system for a data center is characterized in that a solar photovoltaic panel 8 is installed on the roof of the data center, the output end of the solar photovoltaic panel 8 is connected to a solar controller, and the load port of the solar controller is connected to the power supply end of the compressor 1 through a cable.

[0008] The above-mentioned carbon dioxide refrigeration and temperature control system for a data center is characterized in that: the compressor 1 is connected to the condenser 2 through a first pipe 13, the condenser 2 is connected to the first underground cavity 3 through a second pipe 12, a third pipe 11 is arranged between the first underground cavity 3 and the expansion valve 4, a fourth pipe 10 is arranged between the expansion valve 4 and the second underground cavity 5, a fifth pipe 9 is arranged between the second underground cavity 5 and the evaporator 6, a sixth pipe is arranged between the evaporator 6 and the third underground cavity 7, and a seventh pipe 15 is arranged between the third underground cavity 7 and the compressor 1.

[0009] The above-mentioned carbon dioxide refrigeration and temperature control system for a data center is characterized in that: a first valve 14-1 is provided on the second pipeline 12, a second valve 14-2 is provided on the third pipeline 11, a third valve 14-3 is provided on the fifth pipeline 9, a fourth valve 14-4 is provided on the sixth pipeline, and a fifth valve 14-5 is provided on the seventh pipeline 15.

[0010] The above-mentioned carbon dioxide refrigeration and temperature control system for a data center is characterized in that: a pressure sensor and a flow sensor are provided on the fifth pipeline 9 connected to the evaporator 6;

[0011] An internal temperature sensor is arranged inside the data center, and the internal temperature sensor, pressure sensor and flow sensor are all connected to a computer.

[0012] At the same time, a method for controlling a carbon dioxide refrigeration and temperature control system is provided, characterized in that the method comprises the following steps:

[0013] Step 1: CO2 Cooling in Data Centers:

[0014] Step 101: The compressor 1 compresses the low-pressure carbon dioxide gas in the third underground cavity 7 into high-pressure carbon dioxide gas. The high-pressure carbon dioxide gas is output from the compressor 1 and enters the condenser 2 through the first pipeline 13. The condenser 2 performs heat exchange by water cooling or air cooling to cool and condense the high-pressure carbon dioxide gas into liquid. The liquid carbon dioxide is output from the condenser 2 and stored in the first underground cavity 3 through the second pipeline 12.

[0015] Step 102: Control the flow rate and pressure of liquid carbon dioxide through the second valve 14-2, adjust the opening of the expansion valve 4 to reduce the pressure, and convert it into a low-temperature and low-pressure gas-liquid mixture, which is stored in the second underground cavity 5;

[0016] Step 103: Control the low-temperature and low-pressure gas-liquid mixture in the second underground cavity 5 to be transported to the evaporator 6 through the fifth pipeline 9 through the third valve 14-3. After the low-temperature and low-pressure gas-liquid mixture enters the evaporator 6, the liquid carbon dioxide in the gas-liquid mixture evaporates rapidly to absorb heat from the surrounding air, thereby cooling the air inside the data center.

[0017] Step 2: Temperature control of data center:

[0018] Step 201: When the evaporator 6 cools the air inside the data center, the internal temperature sensor detects the temperature inside the data center in real time according to the set sampling time Δt, obtains the internal temperature detection value at each sampling time and sends it to the computer;

[0019] Step 202: The computer determines the internal temperature according to the detected internal temperature value and the internal temperature setting value T set , obtain the temperature error value and the temperature error value change rate;

[0020] Step 203, the computer inputs the acquired temperature error value and the temperature error value change rate into the fuzzy PID controller; wherein the temperature error value in the fuzzy PID controller has a value range of [-5, +5], and the temperature difference error value change rate has a value range of [-5, +5]; the output of the fuzzy PID controller is the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd;

[0021] Step 204: The computer uses the weight of the fuzzy rule as an optimization target, adopts the gray wolf algorithm, sets the number of gray wolf populations, the maximum number of iterations, and the search range of the weight of the fuzzy rule, sets the weight of the fuzzy rule to the individual position of the wolf group, and randomly initializes the gray wolf population parameters;

[0022] Step 205, construct the fitness function of ITAE as the objective function, iteratively update the position of the gray wolf until the maximum number of iterations is met, and then return to the position of the Alpha wolf after the iterative process is completed, which is the optimal value of the weight of the fuzzy rule;

[0023] Step 206: The computer assigns the optimal value of the weight of the fuzzy rule to the fuzzy PID controller to obtain the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd;

[0024] Step 207: adjust the third valve 14-3 based on the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd in step 206 until the internal temperature detection value meets the internal temperature setting value T set .

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The present invention sets carbon dioxide as a cold source. The system has the advantages of long life and low maintenance cost, and achieves efficient refrigeration effect in the compression, condensation, expansion and evaporation cycles, reducing pollution to the environment.

[0027] 2. The present invention adjusts the opening of the expansion valve by reducing the pressure and converting it into a low-temperature and low-pressure gas-liquid mixture, which is stored in the second underground cavity. The low-temperature and low-pressure gas-liquid mixture is conveniently transported to the evaporator for refrigeration. The gas-liquid mixture is used to achieve uniform distribution of the mixed refrigerant in the evaporator, thereby improving the cooling effect.

[0028] 3. In the present invention, the carbon dioxide after passing through the evaporator enters the third underground cavity for collection, reducing energy waste. At the same time, the carbon dioxide after energy release enters the third underground cavity for the next cycle, realizing the gas energy storage cycle and improving energy utilization efficiency. This method is more environmentally friendly, safe and economically beneficial.

[0029] In summary, the present invention is reasonably designed and effectively utilizes carbon dioxide for heat exchange and cooling of a data center. The carbon dioxide after heat exchange is recycled, which can not only achieve efficient cooling of the data center, but also reduce carbon dioxide energy consumption.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the present invention.

[0032] Description of reference numerals:

[0033] 1—compressor; 2—condenser; 3—first underground cavity;

[0034] 4—Expansion valve; 5—Second underground chamber; 6—Evaporator;

[0035] 7—third underground cavity; 8—solar photovoltaic panel; 9—fifth pipeline;

[0036] 10—the fourth pipeline; 11—the third pipeline; 12—the second pipeline;

[0037] 13—first pipeline; 14-1—first valve; 14-2—second valve;

[0038] 14-3—the third valve; 14-4—the fourth valve; 14-5—the fifth valve;

[0039] 15—The seventh pipeline. DETAILED DESCRIPTION

[0040] like Figure 1 As shown, a carbon dioxide refrigeration and temperature control system for a data center of the present invention includes a compressor 1, a condenser 2, a first underground cavity 3, an expansion valve 4, a second underground cavity 5, an evaporator 6 and a third underground cavity 7 which are connected in a closed loop in sequence, wherein the third underground cavity 7 is connected to the compressor 1, liquid carbon dioxide is stored in the first underground cavity 3, gas-liquid mixed carbon dioxide is stored in the second underground cavity 5, and low-pressure carbon dioxide gas and carbon dioxide gas after heat exchange are stored in the third underground cavity 7.

[0041] In this embodiment, a solar photovoltaic panel 8 is installed on the roof of the data center, and the output end of the solar photovoltaic panel 8 is connected to a solar controller, and the load port of the solar controller is connected to the power supply end of the compressor 1 through a cable.

[0042] In this embodiment, the compressor 1 is connected to the condenser 2 through a first pipe 13, the condenser 2 is connected to the first underground cavity 3 through a second pipe 12, a third pipe 11 is arranged between the first underground cavity 3 and the expansion valve 4, a fourth pipe 10 is arranged between the expansion valve 4 and the second underground cavity 5, a fifth pipe 9 is arranged between the second underground cavity 5 and the evaporator 6, a sixth pipe is arranged between the evaporator 6 and the third underground cavity 7, and a seventh pipe 15 is arranged between the third underground cavity 7 and the compressor 1.

[0043] In this embodiment, a first valve 14 - 1 is provided on the second pipeline 12 , a second valve 14 - 2 is provided on the third pipeline 11 , a third valve 14 - 3 is provided on the fifth pipeline 9 , a fourth valve 14 - 4 is provided on the sixth pipeline 14 , and a fifth valve 14 - 5 is provided on the seventh pipeline 15 .

[0044] In this embodiment, a pressure sensor and a flow sensor are provided on the fifth pipe 9 connected to the evaporator 6;

[0045] An internal temperature sensor is arranged inside the data center, and the internal temperature sensor, pressure sensor and flow sensor are all connected to a computer.

[0046] In this embodiment, when implemented, the system can reuse carbon dioxide for efficient cooling of the data center.

[0047] In this embodiment, during implementation, the pressure of the compressor is adjusted and controlled in real time so that the compressor 1 compresses the low-pressure carbon dioxide gas in the third underground cavity 7 into high-pressure carbon dioxide gas, with the low pressure being 500kPa to 1000kPa and the high pressure being 2000kPa to 3000kPa.

[0048] In this embodiment, during specific implementation, the condenser 2 is located outside the system, connected to the underground cavity 3 through the second pipeline 12, and the flow of carbon dioxide is controlled by the first valve 14-1.

[0049] In this embodiment, during specific implementation, the high-pressure carbon dioxide gas flows through the condenser 2, and the condenser 2 performs heat exchange with the carbon dioxide gas through water cooling or air cooling to efficiently cool the carbon dioxide gas.

[0050] Among them, the water cooling method uses water as a cooling medium to take away the heat of the carbon dioxide gas through the cooling water pipe in the condenser 2. After absorbing the heat of the carbon dioxide, the cooling water is pumped to a cooling tower or a heat exchanger to exchange heat with the outside air and dissipate the heat. The cooled water is recycled back to the condenser 2 and the process is repeated.

[0051] The air cooling method uses air as a cooling medium. The fan blows the outside air through the heat sink or fin tube in the condenser 2 to take away the heat of the carbon dioxide gas, so as to maximize the heat exchange area and improve the condensation efficiency. After the carbon dioxide is cooled by the air in the condenser 2, it condenses into a liquid state, and the air dissipates the heat into the environment. The air cooling method does not require a water source and is suitable for places with water shortage or good air circulation conditions.

[0052] In this embodiment, during specific implementation, the cooling method of the condenser 2 can be selected according to the geographical location and climatic conditions of the data center. The water cooling system realizes heat exchange by connecting to the cooling tower, while the air cooling system dissipates heat to the outside through forced ventilation.

[0053] In this embodiment, during specific implementation, the first underground cavity 3, the second underground cavity 5 and the third underground cavity 7 are located 5-10 meters underground, which can further enhance the heat insulation capacity, reduce corrosion and increase the service life.

[0054] In this embodiment, during specific implementation, carbon dioxide in various states is stored in underground cavities of different sizes. Each underground cavity is an ellipsoidal structure, and each cavity has an inlet and an outlet.

[0055] In this embodiment, during specific implementation, the carbon dioxide liquid liquefied by the condenser 2 is temporarily stored in the first underground cavity 3 .

[0056] The flow rate and pressure of liquid carbon dioxide are controlled by the second valve 14-2. The expansion valve 4 is located between the first underground cavity 3 and the second underground cavity 5. The opening of the expansion valve 4 is adjusted to achieve a decompression effect, and the mixture is converted into a low-temperature and low-pressure gas-liquid mixture, which is stored in the second underground cavity 5; the low pressure is 500kPa to 1000kPa; the low temperature is -10℃ to 10℃;

[0057] The gas-liquid mixture in the second underground cavity 5 is controlled to be transported to the evaporator 6 through the fifth pipeline 9 by means of the third valve 14 - 3 ;

[0058] In this embodiment, the opening of the expansion valve 4 can be adjusted during implementation to ensure that the pressure and temperature of the carbon dioxide before entering the evaporator 6 meet the design requirements of the system. The design of the expansion valve 4 takes into account the load fluctuation of the data center and can respond to changes in cooling demand in a short time.

[0059] In this embodiment, during specific implementation, the evaporator 6 is located inside the data center, absorbs heat from the air in the data center, and is used to convert the low-temperature and low-pressure gas-liquid mixture into heat-exchanged gas output through heat exchange, thereby cooling the air in the data center to achieve a refrigeration effect.

[0060] The carbon dioxide gas after heat exchange flowing through the evaporator 6 is connected to the third underground cavity 7 through the sixth pipeline, and the carbon dioxide gas after heat exchange is fed back and stored in the third underground cavity 7. The low-pressure carbon dioxide gas in the third underground cavity 7 is connected to the compressor 1 through the seventh pipeline 15 to facilitate participation in the next cycle.

[0061] In this embodiment, during specific implementation, the heat exchange tubes in the evaporator 6 are made of high thermal conductivity materials to maximize the heat exchange efficiency. The cooled air is redistributed to the interior of the data center through the fan to achieve uniform cooling.

[0062] In this embodiment, during implementation, a solar controller is provided to provide a stable power supply.

[0063] In this embodiment, during specific implementation, a pressure sensor and a temperature sensor may be provided on the first pipeline 13, a flow sensor and a temperature sensor may be provided on the second pipeline 12, and a pressure sensor and a flow sensor may be provided on the fourth pipeline 10; sensors are used to monitor the real-time status of the system to ensure that all parts of the system operate normally.

[0064] In this embodiment, during specific implementation, a pressure sensor and a flow sensor may also be provided on the fifth pipeline 9 to facilitate monitoring of other parameters.

[0065] In this embodiment, during specific implementation, the sampling time Δt and the internal temperature setting value T setIt is set according to actual requirements and is not specifically limited.

[0066] In this embodiment, during the specific implementation, for the data center equipped with the evaporator 6, temperature, pressure, and flow sensors are installed, and the evaporator 6 is intelligently regulated using an intelligent control algorithm based on the real-time status obtained by the data center sensors and the reasonable state setting value of carbon dioxide for normal operation of the data center, so as to achieve the purpose of cooling and temperature control of the data center.

[0067] In this embodiment, a method for controlling a carbon dioxide refrigeration and temperature control system of a data center is provided, the method comprising the following steps:

[0068] Step 1: CO2 Cooling in Data Centers:

[0069] Step 101: The compressor 1 compresses the low-pressure carbon dioxide gas in the third underground cavity 7 into high-pressure carbon dioxide gas. The high-pressure carbon dioxide gas is output from the compressor 1 and enters the condenser 2 through the first pipeline 13. The condenser 2 performs heat exchange by water cooling or air cooling to cool and condense the high-pressure carbon dioxide gas into liquid. The liquid carbon dioxide is output from the condenser 2 and stored in the first underground cavity 3 through the second pipeline 12.

[0070] Step 102: Control the flow rate and pressure of liquid carbon dioxide through the second valve 14-2, adjust the opening of the expansion valve 4 to reduce the pressure, and convert it into a low-temperature and low-pressure gas-liquid mixture, which is stored in the second underground cavity 5;

[0071] Step 103: Control the low-temperature and low-pressure gas-liquid mixture in the second underground cavity 5 to be transported to the evaporator 6 through the fifth pipeline 9 through the third valve 14-3. After the low-temperature and low-pressure gas-liquid mixture enters the evaporator 6, the liquid carbon dioxide in the gas-liquid mixture evaporates rapidly to absorb heat from the surrounding air, thereby cooling the air inside the data center.

[0072] Step 2: Temperature control of data center:

[0073] Step 201: When the evaporator 6 cools the air inside the data center, the internal temperature sensor detects the temperature inside the data center in real time according to the set sampling time Δt, obtains the internal temperature detection value at each sampling time and sends it to the computer;

[0074] Step 202: The computer determines the internal temperature according to the detected internal temperature value and the internal temperature setting value T set , obtain the temperature error value and the temperature error value change rate;

[0075] Step 203, the computer inputs the acquired temperature error value and the temperature error value change rate into the fuzzy PID controller; wherein the temperature error value in the fuzzy PID controller has a value range of [-5, +5], and the temperature difference error value change rate has a value range of [-5, +5]; the output of the fuzzy PID controller is the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd;

[0076] Step 204: The computer uses the weight of the fuzzy rule as an optimization target, adopts the gray wolf algorithm, sets the number of gray wolf populations, the maximum number of iterations, and the search range of the weight of the fuzzy rule, sets the weight of the fuzzy rule to the individual position of the wolf group, and randomly initializes the gray wolf population parameters;

[0077] Step 205, construct the fitness function of ITAE as the objective function, iteratively update the position of the gray wolf until the maximum number of iterations is met, and then return to the position of the Alpha wolf after the iterative process is completed, which is the optimal value of the weight of the fuzzy rule;

[0078] Step 206: The computer assigns the optimal value of the weight of the fuzzy rule to the fuzzy PID controller to obtain the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd.

[0079] In this embodiment, when implemented specifically, the fuzzy set of the fuzzy PID computer is {negative large, negative small, zero, positive small, positive large}, the input includes the temperature error value and the temperature error value change rate, the output is the PID parameters kp, Δki and Δkd, which are the adjustment amounts of the proportional adjustment coefficient, the integral adjustment coefficient and the differential adjustment coefficient respectively, and the membership function of the input and output adopts a triangular membership function;

[0080] The fuzzy set of temperature error value is {negative large (NB), negative small (NS), zero (ZO), positive small (PS), positive large (PB)}; the fuzzy set of temperature error value change rate is {decline (N), stable (Z), increase (P)}; the output variable is defined as the following fuzzy set: proportional adjustment coefficient kp: {lower (L), unchanged (M), increase (H)}; integral adjustment coefficient ki: {lower (L), unchanged (M), increase (H)}; micro-integral adjustment coefficient kd: {lower (L), unchanged (M), increase (H)}.

[0081] That is, the temperature error value fuzzy set {NB, NS, ZO, PS, PB} = {-5, -2, 0, 2, 5}; at the same time, in order to allow the control system to respond to the speed of temperature changes, the domain of the temperature error change rate is also [-5, 5], so the domain of decrease (N) is [-5, 0], the domain of stability (Z) is [-2, 2], and the domain of increase (H) is [0, 5].

[0082] In this embodiment, during specific implementation, the fuzzy rules are as follows in Table 1:

[0083] Table 1 Fuzzy rules

[0084]

[0085] In this embodiment, a weight is assigned to each fuzzy rule during implementation, and the weight represents the contribution of the rule to the final output. At the same time, the weight of the fuzzy rule is different according to different inputs, so the Grey Wolf Optimization Algorithm (GWO) is used to optimize the rule weight.

[0086] In this embodiment, during specific implementation, the weights of the fuzzy rules are combined with the centroid method to finally obtain the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd.

[0087] In summary, the present invention is reasonably designed and effectively utilizes carbon dioxide for heat exchange and cooling of a data center. The carbon dioxide after heat exchange is recycled, which can not only achieve efficient cooling of the data center, but also reduce carbon dioxide energy consumption.

[0088] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A carbon dioxide refrigeration and temperature control system for a data center, characterized in that: The invention comprises a compressor (1), a condenser (2), a first underground cavity (3), an expansion valve (4), a second underground cavity (5), an evaporator (6) and a third underground cavity (7) which are connected in a closed loop in sequence, wherein the third underground cavity (7) is connected to the compressor (1), liquid carbon dioxide is stored in the first underground cavity (3), gas-liquid mixed carbon dioxide is stored in the second underground cavity (5), and low-pressure carbon dioxide gas and carbon dioxide gas after heat exchange are stored in the third underground cavity (7).

2. A carbon dioxide refrigeration and temperature control system for a data center according to claim 1, characterized in that: A solar photovoltaic panel (8) is installed on the roof of the data center, the output end of the solar photovoltaic panel (8) is connected to a solar controller, and the load port of the solar controller is connected to the power supply end of the compressor (1) through a cable.

3. A carbon dioxide refrigeration and temperature control system for a data center according to claim 1, characterized in that: The compressor (1) is connected to the condenser (2) via a first pipe (13); the condenser (2) is connected to the first underground cavity (3) via a second pipe (12); a third pipe (11) is provided between the first underground cavity (3) and the expansion valve (4); a fourth pipe (10) is provided between the expansion valve (4) and the second underground cavity (5); a fifth pipe (9) is provided between the second underground cavity (5) and the evaporator (6); a sixth pipe is provided between the evaporator (6) and the third underground cavity (7); and a seventh pipe (15) is provided between the third underground cavity (7) and the compressor (1).

4. A carbon dioxide refrigeration and temperature control system for a data center according to claim 3, characterized in that: The second pipeline (12) is provided with a first valve (14-1), the third pipeline (11) is provided with a second valve (14-2), the fifth pipeline (9) is provided with a third valve (14-3), the sixth pipeline is provided with a fourth valve (14-4), and the seventh pipeline (15) is provided with a fifth valve (14-5).

5. A carbon dioxide refrigeration and temperature control system for a data center according to claim 1, characterized in that: An internal temperature sensor is arranged inside the data center, and the internal temperature sensor is connected to a computer.

6. A method for controlling the carbon dioxide refrigeration and temperature control system of a data center according to claim 5, characterized in that: The method comprises the following steps: Step 1: CO2 Cooling in Data Centers: Step 101: The compressor (1) compresses the low-pressure carbon dioxide gas in the third underground cavity (7) into high-pressure carbon dioxide gas. The high-pressure carbon dioxide gas is output from the compressor (1) and enters the condenser (2) through the first pipeline (13). The condenser (2) performs heat exchange by water cooling or air cooling to cool the high-pressure carbon dioxide gas and condense it into liquid. The liquid carbon dioxide is output from the condenser (2) and stored in the first underground cavity (3) through the second pipeline (12). Step 102: Control the flow rate and pressure of liquid carbon dioxide through the second valve (14-2), adjust the opening of the expansion valve (4) to reduce the pressure, and convert it into a low-temperature and low-pressure gas-liquid mixture, which is stored in the second underground cavity (5); Step 103: Control the low-temperature and low-pressure gas-liquid mixture in the second underground cavity (5) to be transported to the evaporator (6) through the fifth pipeline (9) through the third valve (14-3); after the low-temperature and low-pressure gas-liquid mixture enters the evaporator (6), the liquid carbon dioxide in the gas-liquid mixture evaporates rapidly and absorbs heat from the surrounding air, thereby cooling the air inside the data center; Step 2: Temperature control of data center: Step 201: During the process of the evaporator (6) cooling the air inside the data center, the internal temperature sensor detects the temperature inside the data center in real time according to the set sampling time Δt, obtains the internal temperature detection value at each sampling time and sends it to the computer; Step 202: The computer determines the internal temperature according to the detected internal temperature value and the internal temperature setting value T set , obtain the temperature error value and the temperature error value change rate; Step 203, the computer inputs the acquired temperature error value and the temperature error value change rate into the fuzzy PID controller; wherein the temperature error value in the fuzzy PID controller has a value range of [-5, +5], and the temperature difference error value change rate has a value range of [-5, +5]; the output of the fuzzy PID controller is the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd; Step 204: The computer uses the weight of the fuzzy rule as an optimization target, adopts the gray wolf algorithm, sets the number of gray wolf populations, the maximum number of iterations, and the search range of the weight of the fuzzy rule, sets the weight of the fuzzy rule to the individual position of the wolf group, and randomly initializes the gray wolf population parameters; Step 205, construct the fitness function of ITAE as the objective function, iteratively update the position of the gray wolf until the maximum number of iterations is met, and then return to the position of the Alpha wolf after the iterative process is completed, which is the optimal value of the weight of the fuzzy rule; Step 206: The computer assigns the optimal value of the weight of the fuzzy rule to the fuzzy PID controller to obtain the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd; Step 207: adjust the third valve (14-3) based on the proportional adjustment coefficient kp, the integral adjustment coefficient ki and the differential adjustment coefficient kd in step 206 until the internal temperature detection value meets the internal temperature setting value T set .

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