Three-stage cooling air cooler applied to data center

Abstract

The invention provides a three-stage cooling air cooler applied to a data center. The three-stage cooling air cooler comprises a sensible heat air cooler, a condensation air cooler, a fan assembly, a spraying assembly and a supercooling air cooler, and the sensible heat air cooler conducts sensible heat cooling on a CO2 working medium; the fan assembly is used for controlling air flow; the spraying assembly is used for spraying water mist to achieve cooperative heat exchange with air. The condensation air cooler, the draught fan assembly and the spraying assembly conduct heat exchange through water mist and air. The supercooling air cooler is used for carrying out dew-point evaporative cooling; the controller is configured to obtain a dry-bulb temperature and a wet-bulb temperature; and based on the dry-bulb temperature and the wet-bulb temperature, a sensible-heat air cooler, a condensation air cooler, a fan assembly, a spraying assembly and a supercooling air cooler are controlled to execute an operation mode. According to the three-stage cooling air cooler, the working medium flow is optimized through a three-stage cooling structure, cooperative heat exchange with the air side is achieved, the heat exchange efficiency is improved, and the pressure drop loss is reduced.

Description

Technical Field

[0001] The present application relates to the field of heat dissipation and cooling technology, and in particular to a three-stage cooling air cooler used in a data center. Background Art

[0002] In transcritical circulation systems, air coolers, as heat exchangers, must cool the CO2 working fluid to a subcritical state under high temperature and pressure, or supercritical pressure conditions. Their performance impacts the system's energy efficiency and operational stability. However, with increasing ambient temperature fluctuations and the normalization of high-load conditions, air coolers, due to their insufficient heat exchange efficiency and limited pressure drop control capabilities, have become a key bottleneck restricting system efficiency improvements.

[0003] CO2 transcritical systems utilize single- or two-stage air cooler structures, based on a split-flow design and single-pass heat exchange mode on the working fluid side. For example, a single-stage air cooler achieves initial cooling of the CO2 sensible heat section through a single-pass finned tube structure, while a two-stage air cooler divides the heat exchange process into a sensible heat section and a condensing section through a simple split-flow process. Staged cooling can also be achieved by stacking independent air cooler modules, but this still primarily focuses on the working fluid side process segmentation, lacking optimization of the air side flow velocity distribution and heat and moisture exchange synergy.

[0004] The CO2 transcritical system results in reduced heat exchange efficiency and increased pressure drop loss. Summary of the Invention

[0005] The present application provides a three-stage cooling air cooler for use in a data center to solve the problems of reduced heat exchange efficiency and increased pressure drop loss.

[0006] The present application provides a three-stage cooling air cooler for use in a data center, comprising:

[0007] A sensible heat air cooler, one end of which is connected to an air inlet, and the other end of which is connected to a condensing air cooler, for receiving CO2 gas at a preset temperature; the sensible heat air cooler is used to perform sensible heat cooling on the CO2 working medium;

[0008] Fan assembly, used to control air flow;

[0009] Spray assembly, used to spray water mist and cooperate with air for heat exchange;

[0010] The condensing air cooler, the fan assembly and the spray assembly perform heat exchange using water mist and air;

[0011] One end of the condensing air cooler is connected to a subcooling air cooler, and the subcooling air cooler is used for dew point evaporative cooling;

[0012] The controller is configured as:

[0013] Get dry bulb temperature and wet bulb temperature;

[0014] Based on the dry-bulb temperature and the wet-bulb temperature, the sensible heat air cooler, the condensing air cooler, the fan assembly, the spray assembly, and the subcooling air cooler are controlled to execute an operation mode.

[0015] In some feasible embodiments, the fan assembly includes a first fan group and a second fan group;

[0016] The controller is configured to:

[0017] If the dry-bulb temperature is less than a first temperature threshold and the humidity is less than a first humidity threshold, the sensible heat air cooler and the fan assembly are controlled to execute a first cooling mode.

[0018] In some feasible embodiments, the first air inlet, the first water collector, the second air inlet, the first filler, and the third water collector are further included;

[0019] When executing the first cooling mode, the controller is specifically configured to:

[0020] An on command is sent to the fan assembly to execute a first cooling mode. In the first cooling mode, external air enters from the first air inlet, passes through the condensing air cooler, the first water collector, and the sensible heat air cooler in sequence, and is discharged through the first fan unit; and external air enters from the second air inlet, passes through the first filler, the third water collector, and the sensible heat air cooler in sequence, and is discharged through the first fan unit.

[0021] In some feasible embodiments, the fan assembly includes a first fan group and a second fan group, and the spray assembly includes a first water pump and a first nozzle;

[0022] The controller is configured to:

[0023] If the dry-bulb temperature is less than a second temperature threshold and the humidity is less than a second humidity threshold, the sensible heat air cooler, the condensing air cooler, the fan assembly, and the spray assembly are controlled to execute a second cooling mode, wherein the second temperature threshold is greater than the first temperature threshold, and the second humidity threshold is greater than the first humidity threshold.

[0024] In some feasible embodiments, the system further includes a first air inlet, a first water collector, a second air inlet, a first filler, a third water collector, a first water tray, a water spray tray, a water distributor, a heat exchanger, and a third air inlet;

[0025] The first nozzle is used to spray out the water in the first water pan delivered by the first water pump; the water pan includes a first channel connected to the water distributor, and the first water pan is arranged at the bottom of the heat exchanger;

[0026] The first filler is arranged at the bottom of the condensing air cooler;

[0027] When the controller executes the second cooling mode, the controller is specifically configured to:

[0028] Send an open command to the fan assembly and the spray assembly to execute the second cooling mode. In the second cooling mode, external air enters from the first air inlet, passes through the condensing air cooler, the first water collector, and the sensible heat air cooler in sequence, and is discharged through the first fan unit; external air enters from the second air inlet, passes through the first filler, the third water collector, and the sensible heat air cooler in sequence, and is discharged through the first fan unit; the water mist sprayed by the first nozzle performs heat and moisture exchange on the surface of the condensing air cooler, and the water mist passing through the condensing air cooler and the air entering from the second air inlet perform heat and moisture exchange at the first filler. The heat exchanger receives water transported by the water spray tray through the first channel, and after heat exchange with the air entering from the third air inlet, it flows into the first water tray.

[0029] In some feasible embodiments, the fan assembly includes a first fan group and a second fan group, and the spray assembly includes a first water pump, a first nozzle, and a second water pump, a second nozzle;

[0030] The controller is configured to:

[0031] If the dry-bulb temperature is less than or equal to the temperature critical value, and the CO2 gas exhaust pressure is less than or equal to the critical pressure, the sensible heat air cooler, condensing air cooler, subcooling air cooler, fan assembly, and spray assembly are controlled to execute the third cooling mode, wherein the temperature critical value is greater than the second temperature threshold.

[0032] In some feasible embodiments, the system further includes a first air inlet, a first water collector, a second air inlet, a first filler, a third water collector, a first water tray, a water spray tray, a water distributor, a heat exchanger, and a third air inlet;

[0033] The first nozzle is used to spray out the water delivered by the first water pump in the first water pan; the water pan includes a first channel and a second channel, the first channel is connected to the water distributor, and the second channel is connected to the second filler, and the first water pan is arranged at the bottom of the heat exchanger;

[0034] When executing the third cooling mode, the controller is specifically configured to:

[0035] A start command is sent to the fan assembly and the spray assembly to execute the third cooling mode. The third cooling mode is that external air enters from the first air inlet, exchanges heat and moisture with the water mist sprayed from the first nozzle on the surface of the condensing air cooler, and the air that has undergone heat and moisture exchange passes through the first water collector and cools the CO2 gas in the sensible air cooler at the sensible air cooler. The water mist that has undergone heat and moisture exchange performs a secondary heat and moisture exchange with the air entering from the second air inlet at the first filler. The wind after the secondary heat and moisture exchange passes through the third water collector and the sensible air cooler and is discharged through the first fan unit; the heat exchanger receives the water transported by the water spray tray through the first channel and exchanges heat with the air entering from the third air inlet. The water transported by the second filler through the second channel exchanges heat and moisture with the air that has undergone heat exchange in the heat exchanger. After that, the wind that has undergone heat and moisture exchange exchanges heat and moisture with the water mist sprayed from the second nozzle and transported by the second water pump in the supercooling air cooler.

[0036] In some feasible embodiments, a water side connecting port is provided on the first water tray, and a water side overflow port is provided between the first water tray and the second water tray. When the water volume in the second water tray reaches a threshold, the water flows from the water side overflow port into the water side connecting port.

[0037] In some feasible embodiments, the fan assembly includes a first fan group and a second fan group, and the spray assembly includes a first water pump, a first nozzle, and a second water pump, a second nozzle;

[0038] The controller is configured to:

[0039] If the dry-bulb temperature is greater than the temperature critical value and the CO2 gas exhaust pressure is greater than the critical pressure, the sensible heat air cooler, condensing air cooler, subcooling air cooler, fan assembly, and spray assembly are controlled to execute the fourth cooling mode, wherein the temperature critical value is greater than the second temperature threshold.

[0040] In some feasible embodiments, the system further includes a first air inlet, a first water collector, a second air inlet, a first filler, a third water collector, a first water tray, a first nozzle, a water tray, a water distributor, a heat exchanger, a third air inlet, and a liquid outlet;

[0041] The first nozzle is used to spray out the water delivered by the first water pump in the first water pan; the water pan includes a first channel and a second channel, the first channel is connected to the water distributor, and the second channel is connected to the second filler, and the first water pan is arranged at the bottom of the heat exchanger;

[0042] When executing the fourth cooling mode, the controller is specifically configured to:

[0043] Send an opening instruction to the fan assembly and the spray assembly to execute the fourth cooling mode. In the fourth cooling mode, external air enters from the first air inlet, cools in the sensible heat air cooler, and the cooled air passes through the condensing air cooler and is converted into CO2 liquid. The CO2 liquid enters the subcooling air cooler for dew point evaporation cooling and is discharged through the liquid outlet; external air enters from the first air inlet and exchanges heat and moisture with the water mist sprayed from the first nozzle on the surface of the condensing air cooler. The air that has undergone heat and moisture exchange passes through the first water collector and cools the sensible heat air cooler at the sensible heat air cooler. The CO2 gas in the device performs a secondary heat and moisture exchange with the water mist after heat and moisture exchange, and the air entering from the second air inlet at the first filler. The wind after the secondary heat and moisture exchange passes through the third water collector and the sensible heat air cooler and is discharged through the first fan unit; the heat exchanger receives the water transported by the water tray through the first channel, and exchanges heat with the air entering from the third air inlet. The water transported by the second filler through the second channel exchanges heat and moisture with the air undergoing heat exchange in the heat exchanger. The wind that has undergone heat and moisture exchange is in the supercooling air cooler and exchanges moisture with the water mist sprayed from the second nozzle transported by the second water pump.

[0044] From the above technical solution, it can be seen that the present application provides a three-stage cooling air cooler for use in a data center, comprising: a sensible heat air cooler, a condensing air cooler, a fan assembly, a spray assembly, and a subcooling air cooler, wherein one end of the sensible heat air cooler is connected to an air inlet, and the other end of the sensible heat air cooler is connected to a condensing air cooler for receiving CO2 gas at a preset temperature; the sensible heat air cooler is used to sensibly cool the CO2 working medium; the fan assembly is used to control the air flow; the spray assembly is used to spray water mist and cooperate with the air to exchange heat; the condensing air cooler and the fan assembly and the spray assembly use water mist to perform heat exchange with the air; one end of the condensing air cooler is connected to a subcooling air cooler, and the subcooling air cooler is used to perform dew point evaporative cooling; the controller is configured to: obtain dry-bulb temperature and wet-bulb temperature; based on the dry-bulb temperature and wet-bulb temperature, control the sensible heat air cooler, condensing air cooler, fan assembly, spray assembly and subcooling air cooler to execute the operating mode. The three-stage cooling air cooler optimizes the working medium flow and the coordinated heat exchange on the air side through the three-stage cooling structure, thereby improving the heat exchange efficiency and reducing the pressure drop loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0046] Figure 1 A schematic structural diagram of a three-stage cooling air cooler for use in a data center provided in an embodiment of the present application.

[0047] Among them, 1-air inlet; 2-first fan unit; 3-sensible heat air cooler, 4-first water collector, 5-first air inlet; 6-first nozzle; 7-condensing air cooler; 8-first filler; 9-second air inlet; 10-water distributor; 11-third air inlet; 12-first water pump; 13-first water pan; 14-water side connecting port; 15-heat exchanger; 16-water side overflow port; 17-second filler; 18-second water pan; 19-subcooled air cooler; 20-second water collector; 21-second water pump; 22-liquid outlet; 23-second fan unit; 24-second nozzle; 25-water spray pan; 26-third water collector. DETAILED DESCRIPTION

[0048] The following embodiments are described in detail, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numbers in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following embodiments are not intended to represent all possible implementations consistent with the present application. They are merely examples of systems and methods consistent with certain aspects of the present application, as detailed in the claims.

[0049] Single-stage compression refrigeration systems rely on a single compressor to compress low-temperature, low-pressure gaseous refrigerant to a high-temperature, high-pressure state. The core bottleneck lies in the physical limits of the compression ratio. While the ideal compression ratio range is 3 to 6, data center cooling systems with evaporating temperatures of approximately 5 to 15°C and condensing temperatures of approximately 30 to 40°C typically achieve a compression ratio of 2.5 to 4.0, which falls within the compressor's efficient operating range.

[0050] Server cooling in data centers requires an inlet water temperature of 10-35°C (10-35°C), corresponding to an evaporation temperature of 5-15°C (5-15°C), which fits the optimal operating range for single-stage compression. This system operates 24 / 7 without frequent start-stop requirements, avoiding the start-stop losses associated with single-stage systems. Air cooling can achieve 20kW per cabinet, eliminating the need for industrial-grade cryogenic cooling.

[0051] Therefore, the three-stage cooling air cooler provided in this application is applied to data centers.

[0052] Conventional CO2 transcritical systems mostly use a single-stage or two-stage air cooler structure, and their heat exchange process is a single-flow or simple split-flow design. This type of structure has the following prominent problems:

[0053] 1. Insufficient heat exchange efficiency: In high temperature environments, single-stage air coolers are unable to fully cool the CO2 working fluid due to unreasonable heat exchange area and process distribution, resulting in excessively high exhaust temperature of the system and a significant increase in compressor energy consumption.

[0054] 2. Large pressure drop loss: Traditional single-flow design easily increases the flow resistance of the working fluid, especially under high-pressure conditions, where the pressure drop loss further reduces the effective cooling capacity of the system.

[0055] 3. Poor adaptability to changing operating conditions: Existing air coolers lack dynamic adjustment capabilities and are unable to optimize the heat exchange path according to changes in ambient temperature or load. This results in redundant or insufficient cooling capacity under some operating conditions, affecting the system's energy efficiency throughout the year.

[0056] 4. Structural redundancy and high cost: Some solutions achieve hierarchical cooling by stacking multiple independent air coolers. However, the multi-module series design results in bulky equipment, complex piping, and significantly increased manufacturing costs.

[0057] Furthermore, research on multi-stage air coolers has largely focused on flow diversion design on the working fluid side, with insufficient attention paid to the coordinated optimization of the air side (cooling medium). This is particularly true when air velocity distribution is uneven, leading to significant localized heat exchange inefficiencies. Furthermore, traditional finned tube structures are prone to stress concentration under high-pressure CO2 conditions, posing a risk of leakage and further limiting the reliability and service life of the air cooler.

[0058] To solve the above problems, Figure 1 As shown, some embodiments of the present application provide a three-stage cooling air cooler for use in data centers. Through multi-stage cooling and process optimization, the step-by-step cooling and pressure drop control of the CO2 working fluid are achieved, while the uniformity of heat exchange on the air side is improved, thereby breaking through the energy efficiency bottleneck of the existing system.

[0059] The three-stage cooling air cooler used in the data center includes: a sensible heat air cooler 3, one end of the sensible heat air cooler 3 is connected to an air inlet, and the other end of the sensible heat air cooler 3 is connected to a condensing air cooler 7 for receiving CO2 gas at a preset temperature; the sensible heat air cooler 3 is used to sensibly cool the CO2 working medium, and adopts a stainless steel tube and stainless steel fin structure to initially reduce the CO2 gas temperature to the ambient dry bulb temperature +10°C. It is made of stainless steel tubes and stainless steel fins, with a diameter of 10mm and a wall thickness of 1mm.

[0060] The condensing air cooler 7 incorporates wet-bulb evaporative cooling technology, using a synergistic heat exchange between spray water and air to reduce the CO2 temperature to a wet-bulb temperature of +3°C. It is constructed from stainless steel tubing with a diameter of 10mm and a wall thickness of 1mm. The optimized structural design, using pressure-resistant materials such as stainless steel and hot-dip galvanized steel, alleviates stress concentration under high-pressure operating conditions, reduces the risk of leakage, and extends service life.

[0061] The fan assembly is used to control air flow. It provides horizontal or vertical air flow, driving ambient air through the air cooler and removing heat released by the CO2 refrigerant. In some embodiments, it includes a first fan unit 2 and a second fan unit 23. The fan units can be EC axial flow fans. The first fan unit 2 is located above the sensible heat air cooler 3, and the second fan unit 23 is located downstream of the subcooling air cooler 19. The speed can be adjusted via variable frequency control to adapt to different heat exchange requirements.

[0062] The spray assembly is used to spray water mist, synergizing heat exchange with the air. In some embodiments, the spray assembly includes a first water pump 12, a first nozzle 6, a second water pump 21, and a second nozzle 24. The water pump is used to drive circulating water into the nozzle and maintain the required spray pressure. The nozzle is located above the condensing air cooler 7 and the subcooling air cooler 19. It is used to spray water mist onto the air cooler surface under high ambient temperature conditions, forming a thin water film to enhance the heat exchange efficiency between the air and the refrigerant.

[0063] The condensing air cooler 7, the fan assembly and the spray assembly use water mist to perform heat exchange with air; one end of the condensing air cooler 7 is connected to a subcooling air cooler 19, and the subcooling air cooler 19 is used for dew point evaporative cooling. The dew point evaporative cooling technology is used to further reduce the CO2 temperature to the wet bulb temperature of -3°C to achieve subcooling.

[0064] The gas cooler in this embodiment is a series structure, using different materials (stainless steel pipes, hot-dip galvanized steel pipes) and heat exchange forms (sensible heat, wet-bulb evaporation, dew-point evaporation), and includes a sensible heat section air cooler, a condensing section air cooler, and a subcooling section air cooler, which correspond to the three stages of gas cooling, liquefaction condensation, and subcooling treatment in the CO2 refrigeration system, respectively. Each air cooler is arranged in sequence on the CO2 refrigerant flow path, so that the CO2 gas in a high-temperature and high-pressure state can complete heat removal and phase change in the step-by-step heat exchange process. The integrated three-stage cooling structure replaces the traditional multi-module series solution, significantly reducing the size of the equipment while reducing manufacturing costs and installation complexity.

[0065] The controller, which adjusts the fan's operating status based on environmental parameters, can be a PLC or ARM main control unit and features multiple input and output modules. Electrically connected to components such as temperature and humidity sensors, pressure sensors, and fan drivers, the controller collects current system operating parameters in real time and, based on preset logic, determines whether the system is currently suitable for natural cooling dry mode operation. This mode is enabled when the ambient dry-bulb temperature is below a set threshold and humidity is low, allowing the system condenser to utilize air cooling to complete heat exchange. At this point, the controller outputs a command to start the fan while keeping the water pump off, achieving natural dry cooling in the sensible heat exchange section.

[0066] The controller is configured as:

[0067] Get dry bulb temperature and wet bulb temperature;

[0068] Based on the dry-bulb temperature and the wet-bulb temperature, the sensible heat air cooler 3 , the condensing air cooler 7 , the fan assembly, the spray assembly, and the subcooling air cooler 19 are controlled to execute an operation mode.

[0069] The dry-bulb temperature is the actual air temperature measured directly by a standard thermometer, unaffected by water evaporation. The wet-bulb temperature is the temperature measured by wrapping the thermometer's sensing portion with moistened gauze, reflecting the heat absorption effect of water evaporation. It reflects the air's potential cooling capacity. Transcritical, subcritical, natural cooling wet, and natural cooling dry modes are selected based on the ambient dry-bulb and wet-bulb temperatures.

[0070] The start and stop of the water pump is managed by the controller. When it detects that the ambient dry-bulb temperature is higher than the set threshold, the controller outputs a start command, the water pump starts working and drives the spray component to spray; when the ambient temperature returns to the normal range, or the system switches to dry mode, the controller turns off the water pump, realizing intelligent switching and energy-saving operation.

[0071] The three-stage cooling air cooler for data centers provided in the embodiments of the present application achieves effective cooling of high-temperature, high-pressure CO2 gas by sequentially arranging the sensible heat section air cooler, the condensing section air cooler, and the supercooling section air cooler, combined with the coordinated operation of the fan assembly and the spray assembly. The structural design implements segmented heat exchange, and the heat exchange conditions of each stage can be independently adjusted according to the system operating status, improving the system's adaptability. During operation, dry or wet cooling mode can be enabled according to environmental conditions to reduce operating energy consumption. By using a controller to achieve multi-parameter judgment and automatic control, the system's intelligence level is improved, and the cooling process control strategy is optimized.

[0072] Based on pure CO2 natural working fluid and combined with dew point evaporative cooling technology, it reduces dependence on mechanical refrigeration and significantly reduces the overall energy consumption of the system, which meets the needs of environmental protection and sustainable development.

[0073] In traditional single-stage cooling structures, the dramatic changes in CO2 properties during transcritical operation lead to low heat transfer efficiency, which can easily lead to inadequate condensation and large pressure drops. This solution utilizes three subcoolers: sensible heat, condensation, and subcooling. This allows for a staged heat transfer process, effectively mitigating the thermal instability of CO2 during the supercritical to subcritical transition.

[0074] In addition, the controller adaptively adjusts the cooling method according to the operating environment and enables natural dry cooling under appropriate working conditions. This not only reduces the system flow resistance and pressure drop, but also reduces the operation of water pumps and reduces system energy consumption, thus reducing operating costs and equipment failure rates from the source and improving the overall system performance and operational safety.

[0075] Specifically, the cooling mode includes a natural cooling dry mode, i.e., a first cooling mode. In some embodiments, the controller is configured to: if the dry-bulb temperature is less than a first temperature threshold and the humidity is less than a first humidity threshold, control the sensible heat air cooler 3 and the fan assembly to execute the first cooling mode. In some embodiments, the system further includes a first water collector 4, a first air inlet 5, a first nozzle 6, a first filler 8, a second air inlet 9, a water distributor 10, a third air inlet 11, a first water pump 12, a first water tray 13, a heat exchanger 15, a second filler 17, a second water tray 18, a second water collector 20, a second water pump 21, a liquid outlet 22, a second nozzle 24, a water spray tray 25, and a third water collector 26.

[0076] Specifically, the first nozzle 6 is used to spray out the water in the first water tray 13 transported by the first water pump 12; the water spray tray 25 includes a first channel and a second channel, the first channel is connected to the water distributor 10, and the second channel is connected to the second filler 17, the first water tray 13 is arranged at the bottom of the heat exchanger 15, and the first filler 8 is arranged at the bottom of the condensing air cooler 7.

[0077] Heat exchanger 15 is a spiral-wound dew-point heat exchanger 15 made of hot-dip galvanized steel tubing with a diameter of 25 mm. It works in conjunction with a spiral water distributor 10 to achieve uniform water distribution and efficient heat exchange. Water flows through the water pan 25 within the spiral-wound dew-point heat exchanger 15, where it is evenly distributed by the spiral water distributor 10. Air enters the spiral-wound dew-point heat exchanger 15 from the third air inlet 11 and is forced through the spiral-wound tube bundle by the second fan unit 23 for heat exchange.

[0078] The CO2 gas entering through the air inlet 1 enters the tube of the sensible heat air cooler 3, and the air outside the tube of the condensing air cooler 7 enters through the first air inlet 5 and the second air inlet 9, which are forced to pass through the fin tube bundle for heat exchange under the action of the first air unit 2; the CO2 gas pre-cooled by the condensing air cooler 7 passes through the tube of the condensing air cooler 7; the air outside the sensible heat air cooler 3 enters through the first air inlet 5 and the spray water from the first nozzle 6, and heat and moisture exchange occurs on the outer surface of the coil of the sensible heat air cooler 3; the CO2 liquid cooled by the condensing air cooler 7 passes through the tube of the subcooling air cooler 19; the air outside the subcooling air cooler 19 enters through the third air inlet 11 and the spray water from the second nozzle 24, and heat and moisture exchange occurs on the outer surface of the coil of the subcooling air cooler 19. High-temperature CO2 gas enters from the air inlet 1, flows through the sensible heat air cooler 3 (stainless steel finned tube structure, initial sensible heat cooling), the condensing air cooler 7 (stainless steel tube combined with wet-bulb evaporative cooling) and the subcooling air cooler 19 (wound-type dew-point evaporative cooling), and finally the liquid CO2 is discharged through the liquid outlet 22.

[0079] First air inlet 5: air is driven by the first fan unit 2, flows through the gaps between the fins of the sensible heat air cooler 3, and is discharged after water is separated by the first water collector 4 through pure sensible heat exchange.

[0080] Second air inlet 9 : air enters the condensing air cooler 7 area, and performs wet-bulb evaporation heat exchange with the water mist sprayed by the first nozzle 6 on the surface of the first filler 8 , and the water is recovered by the second water collector 20 .

[0081] The third air inlet 11: the air flows through the cold air cooler 19, and under the cooperation of the spraying of the second nozzle 24 and the second filler 17, the air completes the dew point evaporative cooling with the water film on the surface of the spiral plate heat exchanger 15, and the water is intercepted by the third water collector 26.

[0082] Water circulation in the condensation section: the first water pump 12 pumps water from the first water pan 13, and the water in the first water pan 13 is lifted by the first water pump 12 to the first nozzle 6. The water sprayed from the first nozzle 6 exchanges heat and moisture with the coil surface of the condensing air cooler 7, thereby cooling the CO2 gas inside the condensing air cooler 7. After that, the spray water continues to fall and exchanges heat and moisture with the wind entering through the second air inlet 9 at the first filler 8 again, thereby lowering the water temperature. After that, part of the water at the water pan 25 is passed into the water distributor 10, and the water distributor 10 sprays the water into the heat exchanger 15 for heat exchange with the wind entering through the third air inlet 11. Finally, this part of the spray water returns to the first water pan 13 to complete the cycle.

[0083] Water circulation in the subcooling section: part of the water at the water spray tray 25 enters the water distributor 10, and part flows through the second filler 17. The water distributor 10 sprays part of the water into the heat exchanger 15 for heat exchange with the incoming air, and the other part of the water is sprayed into the second filler 17 for heat and moisture exchange with the wind flowing out of the heat exchanger 15. After the heat and moisture exchange, the wind exchanges heat and moisture on the outer surface of the coil of the subcooling air cooler 19 with the water sprayed from the second nozzle 24 by the second water pump 21.

[0084] In the sensible heat section, high-temperature CO2 gas enters sensible heat air cooler 3 from air inlet 1. The CO2 exchanges sensible heat with the air through the tube wall, initially cooling the temperature to the ambient dry-bulb temperature +10°C. The CO2 then flows through a pipeline into condensing air cooler 7.

[0085] In the condensation section, CO2 enters the condensing air cooler 7. A first water pump 12 pumps water from a first water pan 13, and a water distributor 10 sprays the water into a heat exchanger 15. The first fan unit 2 drives air in through the first air inlet 5. Air then flows through forced convection with the spray water on the packing surface, cooling the CO2 to a wet-bulb temperature of +3°C through wet-bulb evaporation. The CO2 then flows into the subcooling air cooler 19.

[0086] In the subcooling stage, CO2 enters the subcooling air cooler 19. A second water pump 21 pumps water from the second water pan 18 to a second nozzle 24, spraying it onto the coil surface of the subcooling air cooler 19. Air driven by the second fan unit 23 (entering from the third air inlet 11) evaporates the CO2 at its dew point, reducing its temperature to a wet-bulb temperature of -3°C. Liquid CO2 exits the system through the liquid outlet 22.

[0087] Air flow in the sensible heat section: first air inlet 5, fin gap of sensible heat air cooler 3, first water collector 4 (to separate condensed water), and discharged by the first fan unit 2.

[0088] Air flow in the condensation section: the second air inlet 9, the gap between the tube bundles of the condensing air cooler 7, heat and moisture exchange with the spray water on the surface of the first filler 8, the second water collector 20, and the exhaust system.

[0089] Air flow in the subcooling section: the third air inlet 11, the surface of the wound fin heat exchanger 15 and the spray water evaporate at the dew point on the surface of the second filler 17, the third water collector 26, and is discharged by the second fan unit 23.

[0090] The first water tray 13 , the first water pump 12 , the water distributor 10 , sprays to the heat exchanger 15 , and the water film evaporates and falls back to the first water tray 13 .

[0091] Water level balance: It is connected with the second water tray 18 through the water side communication port 14, and the water side overflow port 16 prevents overflow.

[0092] The first temperature threshold may be 20° C., the first humidity threshold may be 15° C., and the CO 2 exhaust pressure (P) is not limited. In some embodiments, when executing the first cooling mode, the controller is specifically configured as follows:

[0093] An open command is sent to the fan assembly to execute the first cooling mode. The first cooling mode is that the external air enters from the first air inlet 5, passes through the condensing air cooler 7, the first water collector 4, and the sensible heat air cooler 3 in sequence, and is discharged through the first fan group 2; and the external air enters from the second air inlet 9, passes through the first filler 8, the third water collector 26, and the sensible heat air cooler 3 in sequence, and is discharged through the first fan group 2.

[0094] In the natural cooling dry mode, the spray assembly and the subcooling air cooler 19 are turned off, and the sensible heat air cooler 3 and the first fan unit 2 are activated. The temperature is reduced only by the sensible heat exchange between the air and the sensible heat section fin pipes, without an evaporative cooling process.

[0095] The high-pressure CO2 gas first enters the first heat exchange stage, the sensible heat air cooler 3, through the gas cooler, which provides air-side heat exchange. Ambient air, driven by the fan assembly, flows across the surface of the sensible heat air cooler 3, absorbing the sensible heat released by the CO2 gas. Due to the low ambient temperature at this stage, the controller determines that spraying or water-side heat exchange is not necessary, and therefore the system's sprayers and water pumps are turned off. Heat exchange between the air and CO2 is accomplished solely through dry air cooling, forming a natural cooling dry mode.

[0096] In the natural cooling dry mode, the CO2 gas is cooled by the sensible heat air cooler 3. At this time, the first fan unit 2 and the second fan unit 23 are turned on, and the first water pump 12 and the second water pump 21 are turned off. The external fresh air of the unit enters from the first air inlet 5, flows through the condensing air cooler 7, the first water collector 4, the sensible heat air cooler 3, and is finally discharged by the first fan unit 2; the external fresh air also enters from the second air inlet 9, flows through the first filler 8, the water collector, the sensible heat air cooler 3, and is finally discharged by the first fan unit 2.

[0097] Through the natural cooling dry mode, part or all of the condensation heat exchange tasks can be completed through natural air cooling under low ambient temperature conditions, thereby achieving significant advantages in system energy efficiency, reliability and maintainability.

[0098] The cooling mode includes a natural cooling mode, i.e., a second cooling mode. In some embodiments, the controller is configured to control the sensible heat air cooler 3, the condensing air cooler 7, the fan assembly, and the spray assembly to execute the second cooling mode if the dry-bulb temperature is less than a second temperature threshold and the humidity is less than a second humidity threshold, wherein the second temperature threshold is greater than the first temperature threshold, and the second humidity threshold is greater than the first humidity threshold. The second temperature threshold can be 28°C, the second humidity threshold can be 19°C, and the CO2 exhaust pressure (P) is unlimited.

[0099] When the controller executes the second cooling mode, the controller is specifically configured to:

[0100] An opening instruction is sent to the fan assembly and the spray assembly to execute the second cooling mode. In the second cooling mode, external air enters from the first air inlet 5, passes through the condensing air cooler 7, the first water collector 4, and the sensible heat air cooler 3 in sequence, and is discharged through the first fan unit 2; external air enters from the second air inlet 9, passes through the first filler 8, the third water collector 26, and the sensible heat air cooler 3 in sequence, and is discharged through the first fan unit 2; the water mist sprayed by the first nozzle 6 performs heat and moisture exchange on the surface of the condensing air cooler 7, and the water mist passing through the supercooling air cooler 19 performs heat and moisture exchange with the air entering from the second air inlet 9 at the first filler 8. The heat exchanger 15 receives the water transported by the water tray 25 through the first channel, and after heat exchange with the air entering from the third air inlet 11, it flows into the first water tray 13.

[0101] In natural cooling mode, the supercooling air cooler 19 and the second nozzle 24 are turned off, and the sensible heat air cooler 3, the condensing air cooler 7, the first fan unit 2, the first water pump 12, and the first nozzle 6 are activated. After the sensible heat section is pre-cooled, the temperature is further reduced through wet-bulb evaporative cooling (spraying water + filler). In a medium temperature / humidity environment, wet-bulb evaporation is used to improve the cooling efficiency.

[0102] The natural cooling wet mode mainly relies on the condensing air cooler 7 to cool the CO2 gas. At this time, the first fan unit 2, the second fan unit 23, the first water pump 12, and the second water pump 21 are turned on. The external fresh air of the unit enters from the first air inlet 5, flows through the condensing air cooler 7, the first water collector 4, the sensible heat air cooler 3, and is finally discharged by the first fan unit 2; the external fresh air also enters from the second air inlet 9, flows through the first filler 8, the water collector, the sensible heat air cooler 3, and is finally discharged by the first fan unit 2; the water in the first water pan 13 is discharged by the first water pump 12 It is lifted to the first nozzle 6, and the water sprayed by the first nozzle 6 exchanges heat and moisture with the coil surface of the condensing air cooler 7, thereby cooling the CO2 gas inside the condensing air cooler 7. After that, the spray water continues to fall and exchanges heat and moisture with the wind entering through the second air inlet 9 at the first filler 8 again, thereby lowering the water temperature. After that, part of the water at the water spray tray 25 is passed into the water distributor 10, and the water distributor 10 sprays the water into the heat exchanger 15 to exchange heat with the wind entering through the third air inlet 11. Finally, this part of the spray water returns to the first water tray 13 to complete the cycle.

[0103] By introducing water spray cooling and an evaporation enhancement mechanism based on air cooling, the cooling effect of CO2 gas is enhanced.

[0104] When the high-temperature CO2 gas is discharged from the compressor, it enters the sensible heat air cooler section 3 of the gas cooler. At this stage, it pushes the outdoor air to flow through the surface of the heat exchanger 15 and takes away some of the heat.

[0105] If the current ambient temperature exceeds the high temperature threshold and the wet-bulb temperature is evaporative (e.g., below 26°C), the controller activates the water spraying system. Circulating water, pressurized by the pump, is fed into the nozzles, forming a uniform, fine mist film on the surface of heat exchanger 15. As the air flows through heat exchanger 15, it comes into full contact with the water film, evaporating the water and absorbing heat. This significantly reduces the temperature on the air side, enhancing cooling capacity.

[0106] During this process, the outer surface of heat exchanger 15 is in a wet film heat exchange state. Because the latent heat of evaporation of the water film is much higher than the sensible heat exchange of air, high condensation efficiency can be maintained under high temperature conditions, effectively suppressing the rise in condensation pressure and preventing a decrease in system energy efficiency. The spray assembly primarily acts on the sensible heat and condensation sections, ensuring that the CO2 refrigerant has completed most of its temperature reduction and phase change process before reaching the subcooling section.

[0107] By spraying water to form a water film on the surface of the heat exchanger 15, the latent heat of evaporation of water is used to enhance the heat exchange between the air and CO2, reduce the air side temperature, and increase the heat exchange driving force, so that the system can maintain efficient cooling capacity under high temperature conditions, improving the heat exchange efficiency of traditional air cooling that is significantly reduced in high temperature weather.

[0108] The cooling mode includes a CO2 transcritical operation mode, i.e., a third cooling mode. In some embodiments, the controller is configured to: if the dry-bulb temperature is less than or equal to the temperature critical value, and the CO2 gas exhaust pressure is less than or equal to the critical pressure, control the sensible heat air cooler 3, the condensing air cooler 7, the subcooling air cooler 19, the fan assembly, and the spray assembly to execute the third cooling mode, wherein the temperature critical value is greater than the second temperature threshold.

[0109] The critical temperature value may be 30° C., and the critical pressure may be 7.38 MPa. Specifically, when executing the third cooling mode, the controller is configured as follows:

[0110] A start command is sent to the fan assembly and the spray assembly to execute the third cooling mode. In the third cooling mode, external air enters from the first air inlet 5 and exchanges heat and moisture with the water mist sprayed from the first nozzle 6 on the surface of the condensing air cooler 7. The air that has undergone heat and moisture exchange passes through the first water collector 4 and cools the CO2 gas in the sensible air cooler 3 at the sensible air cooler 3. The water mist that has undergone heat and moisture exchange performs a secondary heat and moisture exchange with the air entering from the second air inlet 9 at the first filler 8. The air after the secondary heat and moisture exchange passes through the third water collector 26 and the sensible air cooler 3 and is discharged through the first fan unit 2; the heat exchanger 15 receives the water transported by the water tray 25 through the first channel and exchanges heat with the air entering from the third air inlet 11. The water transported by the second filler 17 through the second channel exchanges heat and moisture with the air that has undergone heat exchange in the heat exchanger 15. After that, the air that has undergone heat and moisture exchange exchanges heat and moisture with the water mist sprayed from the second nozzle 24 and transported by the second water pump 21 in the subcooling air cooler 19.

[0111] In the CO2 transcritical operation mode, the three-stage cooling section (sensible heat + wet bulb + dew point evaporation), dual fan units and dual water pumps are enabled to maintain high energy efficiency even in high temperature environments.

[0112] In the CO2 transcritical operation mode, the external fresh air enters from the first air inlet 5, and together with the water in the first water pan 13 sent to the first nozzle 6 by the first water pump 12, heat and moisture exchange is carried out on the coil surface of the condenser air cooler 7, thereby cooling the CO2 gas inside the condenser air cooler 7. After the heat and moisture exchange, the air passes through the first water collector 4 and then cools the CO2 gas inside the sensible heat cooler 3 at the sensible heat cooler 3, and is finally discharged through the first fan unit 2; the spray water that has completed the heat and moisture exchange at the condenser air cooler 7 continues to fall and exchanges heat and moisture with the air entering through the second air inlet 9 again at the first filler 8, thereby The water temperature is lowered. After heat and moisture exchange, the air passes through the water collector and then the sensible heat air cooler 3 before being discharged by the first air unit 2. Part of the water in the water spray pan 25 flows into the water distributor 10, and part flows through the second filler 17. The water distributor 10 sprays some of the water into the heat exchanger 15 for heat exchange with the incoming air, and the remaining part of the water is sprayed into the second filler 17 for heat and moisture exchange with the air flowing out of the heat exchanger 15. After heat and moisture exchange, the air exchanges heat and moisture with the water sprayed from the second nozzle 24 by the second water pump 21 on the outer surface of the coil of the subcooling air cooler 19, thereby cooling the CO2 gas inside the subcooling air cooler 19. A water-side connecting port 14 is provided in the first water pan 13, and a water-side overflow port 16 is provided between the first water pan 13 and the second water pan 18. When the water in the second water pan 18 exceeds the water-side overflow port 16, the water overflows from the second water pan 18 into the first water pan 13.

[0113] During CO2 transcritical operation, the CO2 exhaust pressure is above the CO2 critical pressure, resulting in high exhaust pressure and temperature, and transcritical sensible heat exchange. A three-stage CO2 air cooler is used. Sensible air cooler 3 primarily reduces the exhaust temperature to the CO2 temperature, which is 10°C above the ambient dry-bulb temperature. Condensing air cooler 7 reduces the outlet temperature of sensible air cooler 3 to +3°C above the wet-bulb temperature, and subcooling air cooler 19 reduces the outlet temperature of condensing air cooler 7 to -3°C below the wet-bulb temperature. Condensing air cooler 7 uses wet-bulb evaporative cooling to reduce the outlet temperature to +3°C above the wet-bulb temperature, while subcooling air cooler 19 uses dew-point evaporative cooling to reduce the outlet temperature to -3°C below the wet-bulb temperature. While a traditional air-cooled + wet-pad adiabatic air cooler can reduce the outlet temperature to +5°C below the wet-bulb temperature, a three-stage CO2 air cooler can reduce the outlet temperature to -3°C below the wet-bulb temperature, an 8°C reduction compared to a traditional wet-pad adiabatic air cooler, significantly improving cooling efficiency. When the system is started, the high-temperature CO2 gas first enters the sensible heat exchanger 15 and is cooled by heat exchange on the air side; then it enters the condensing section for gas-liquid phase change, and finally is further cooled in the subcooling section and enters the liquid storage tank.

[0114] If the environmental parameters meet the wet cooling mode startup conditions, when the air passes through the surface of the heat exchanger 15, part of the water film evaporates, taking away significant heat, thereby improving the heat exchange efficiency between the air and CO2.

[0115] During the water spraying process, condensed water forms on the fin surface and naturally drips into the water pan below the heat exchanger 15. If the environmental parameters change, such as the air temperature drops below 28°C, or the wet-bulb temperature rises, resulting in a smaller dry-wet difference, the system returns to dry cooling mode.

[0116] In some embodiments, a water-side connecting port 14 is provided on the first water tray 13 , and a water-side overflow port 16 is provided between the first water tray 13 and the second water tray 18 . When the water volume in the second water tray 18 reaches a threshold, the water flows from the water-side overflow port 16 into the water-side connecting port 14 .

[0117] The cooling mode includes a CO2 subcritical operating mode, i.e., a fourth cooling mode. In some embodiments, the controller is configured to: if the dry-bulb temperature is greater than the temperature critical value and the CO2 gas exhaust pressure is greater than the critical pressure, control the sensible heat air cooler 3, the condensing air cooler 7, the subcooling air cooler 19, the fan assembly, and the spray assembly to execute the fourth cooling mode, wherein the temperature critical value is greater than the second temperature threshold.

[0118] The enabled components are the same as those in transcritical mode, but the compressor power is increased to maintain high pressure, the working fluid operates in the subcritical region, and the compressor load is reduced through three-stage cooling.

[0119] Specifically, when executing the fourth cooling mode, the controller is specifically configured as follows:

[0120] Send an opening instruction to the fan assembly and the spray assembly to execute the fourth cooling mode. In the fourth cooling mode, external wind enters from the first air inlet 5 and is cooled in the sensible heat air cooler 3. The cooled wind passes through the condensing air cooler 7 and is converted into CO2 liquid. The CO2 liquid enters the subcooling air cooler 19 for dew point evaporative cooling and is discharged through the liquid outlet 22. Send an opening instruction to the fan assembly to execute the third cooling mode. In the third cooling mode, external wind enters from the first air inlet 5 and exchanges heat and moisture with the water mist sprayed from the first nozzle 6 on the surface of the condensing air cooler 7. The wind that has undergone heat and moisture exchange passes through the first water collector 4 and is discharged from the sensible heat air cooler. 3 to cool the CO2 gas in the sensible heat air cooler 3, and the water mist that has undergone heat and moisture exchange performs a secondary heat and moisture exchange with the air entering from the second air inlet 9 at the first filler 8. The wind after the secondary heat and moisture exchange passes through the third water collector 26 and the sensible heat air cooler 3 and is discharged through the first fan unit 2; the heat exchanger 15 receives the water transported by the water tray 25 through the first channel, and exchanges heat with the air entering from the third air inlet 11. The water transported by the second filler 17 through the second channel exchanges heat and moisture with the air that has undergone heat exchange in the heat exchanger 15. After that, the wind that has undergone heat and moisture exchange is in the supercooling air cooler 19 and exchanges heat and moisture with the water mist sprayed from the second nozzle 24 transported by the second water pump 21.

[0121] Unlike the CO2 transcritical operation mode, in the CO2 subcritical operation mode, CO2 gas enters through air inlet 1, is pre-cooled in sensible heat air cooler 3, then enters condensing air cooler 7 to condense into CO2 liquid, and finally enters subcooling air cooler 19 for subcooling before being discharged through liquid outlet 22. Sensible heat air cooler 3 is the heat rejection sensible heat section, condensing air cooler 7 is the heat rejection condensing section, and subcooling air cooler 19 is the heat rejection subcooling section.

[0122] The rest of the operation is identical to the CO2 transcritical mode and will not be detailed here. In wet cooling mode, the fan control module dynamically adjusts the fan speed based on the water spray rate to prevent excessive wind speeds from causing water mist to disperse and affect condensation. In dry cooling mode, the fan speed is appropriately increased based on the CO2 condensing pressure and the degree of subcooling to enhance heat exchange.

[0123] After the system is started, the CO2 transcritical high-temperature gas is cooled by a multi-stage air cooler, and the fan unit is started to ensure that the heat exchange intensity on the air side meets the current condensation requirements.

[0124] The present application provides a three-stage cooling air cooler for use in a data center, comprising: a sensible heat air cooler 3, a condensing air cooler 7, a fan assembly, a spray assembly, and a subcooling air cooler 19, wherein one end of the sensible heat air cooler 3 is connected to an air inlet, and the other end of the sensible heat air cooler 3 is connected to the condensing air cooler 7 for receiving CO2 gas at a preset temperature; the sensible heat air cooler 3 is used to perform sensible heat cooling on the CO2 working medium; the fan assembly is used to control the air flow; the spray assembly is used to spray water mist and cooperate with the air to exchange heat; the condensing air cooler 7 and the fan assembly and the spray assembly use water mist to perform heat exchange with the air; one end of the condensing air cooler 7 is connected to the subcooling air cooler 19, and the subcooling air cooler 19 is used to perform dew point evaporative cooling; the controller is configured to: obtain dry-bulb temperature and wet-bulb temperature; and based on the dry-bulb temperature and wet-bulb temperature, control the sensible heat air cooler 3, the condensing air cooler 7, the fan assembly, the spray assembly, and the subcooling air cooler 19 to execute an operating mode. The three-stage cooling air cooler optimizes the working medium flow and the coordinated heat exchange on the air side through the three-stage cooling structure, thereby improving the heat exchange efficiency and reducing the pressure drop loss.

[0125] Similar parts between the embodiments provided in this application can be referenced to each other. The specific implementation methods provided above are only a few examples under the overall concept of this application and do not constitute a limitation on the scope of protection of this application. For those skilled in the art, any other implementation methods expanded based on the scheme of this application without expending creative work shall fall within the scope of protection of this application.

Claims

1. A three-stage cooling air cooler used in a data center, characterized in that: include: A sensible heat air cooler, one end of which is connected to an air inlet, and the other end of which is connected to a condensing air cooler, for receiving CO2 gas at a preset temperature; the sensible heat air cooler is used to perform sensible heat cooling on the CO2 working medium; Fan assembly, used to control air flow; Spray assembly, used to spray water mist and cooperate with air for heat exchange; The condensing air cooler, the fan assembly and the spray assembly perform heat exchange using water mist and air; One end of the condensing air cooler is connected to a subcooling air cooler, and the subcooling air cooler is used for dew point evaporative cooling; The controller is configured as: Get dry bulb temperature and wet bulb temperature; Based on the dry-bulb temperature and the wet-bulb temperature, the sensible heat air cooler, the condensing air cooler, the fan assembly, the spray assembly, and the subcooling air cooler are controlled to execute an operation mode.

2. The three-stage cooling air cooler for use in a data center according to claim 1, characterized in that: The fan assembly includes a first fan group and a second fan group; The controller is configured to: If the dry-bulb temperature is less than a first temperature threshold and the humidity is less than a first humidity threshold, the sensible heat air cooler and the fan assembly are controlled to execute a first cooling mode.

3. The three-stage cooling air cooler for use in a data center according to claim 2, characterized in that: It also includes a first air inlet, a first water collector, a second air inlet, a first filler, and a third water collector; When executing the first cooling mode, the controller is specifically configured to: An on command is sent to the fan assembly to execute a first cooling mode. In the first cooling mode, external air enters from the first air inlet, passes through the condensing air cooler, the first water collector, and the sensible heat air cooler in sequence, and is discharged through the first fan unit; and external air enters from the second air inlet, passes through the first filler, the third water collector, and the sensible heat air cooler in sequence, and is discharged through the first fan unit.

4. The three-stage cooling air cooler for use in a data center according to claim 1, characterized in that: The fan assembly includes a first fan group and a second fan group, and the spray assembly includes a first water pump and a first nozzle; The controller is configured to: If the dry-bulb temperature is less than a second temperature threshold and the humidity is less than a second humidity threshold, the sensible heat air cooler, the condensing air cooler, the fan assembly, and the spray assembly are controlled to execute a second cooling mode, wherein the second temperature threshold is greater than the first temperature threshold, and the second humidity threshold is greater than the first humidity threshold.

5. The three-stage cooling air cooler for use in a data center according to claim 4, characterized in that: It also includes a first air inlet, a first water collector, a second air inlet, a first filler, a third water collector, a first water tray, a water spray tray, a water distributor, a heat exchanger, and a third air inlet; The first nozzle is used to spray out the water in the first water pan delivered by the first water pump; the water pan includes a first channel connected to the water distributor, and the first water pan is arranged at the bottom of the heat exchanger; The first filler is arranged at the bottom of the condensing air cooler; When the controller executes the second cooling mode, the controller is specifically configured to: Send an open command to the fan assembly and the spray assembly to execute the second cooling mode. In the second cooling mode, external air enters from the first air inlet, passes through the condensing air cooler, the first water collector, and the sensible heat air cooler in sequence, and is discharged through the first fan unit; external air enters from the second air inlet, passes through the first filler, the third water collector, and the sensible heat air cooler in sequence, and is discharged through the first fan unit; the water mist sprayed by the first nozzle performs heat and moisture exchange on the surface of the condensing air cooler, and the water mist passing through the condensing air cooler and the air entering from the second air inlet perform heat and moisture exchange at the first filler. The heat exchanger receives water transported by the water spray tray through the first channel, and after heat exchange with the air entering from the third air inlet, it flows into the first water tray.

6. The three-stage cooling air cooler for use in a data center according to claim 1, characterized in that: The fan assembly includes a first fan group and a second fan group, and the spray assembly includes a first water pump, a first nozzle, a second water pump, and a second nozzle; The controller is configured to: If the dry-bulb temperature is less than or equal to the temperature critical value, and the CO2 gas exhaust pressure is less than or equal to the critical pressure, the sensible heat air cooler, condensing air cooler, subcooling air cooler, fan assembly, and spray assembly are controlled to execute the third cooling mode, wherein the temperature critical value is greater than the second temperature threshold.

7. The three-stage cooling air cooler for use in a data center according to claim 6, characterized in that: It also includes a first air inlet, a first water collector, a second air inlet, a first filler, a third water collector, a first water tray, a water spray tray, a water distributor, a heat exchanger, and a third air inlet; The first nozzle is used to spray out the water delivered by the first water pump in the first water pan; the water pan includes a first channel and a second channel, the first channel is connected to the water distributor, and the second channel is connected to the second filler, and the first water pan is arranged at the bottom of the heat exchanger; When executing the third cooling mode, the controller is specifically configured to: A start command is sent to the fan assembly and the spray assembly to execute the third cooling mode. The third cooling mode is that external air enters from the first air inlet, exchanges heat and moisture with the water mist sprayed from the first nozzle on the surface of the condensing air cooler, and the air that has undergone heat and moisture exchange passes through the first water collector and cools the CO2 gas in the sensible air cooler at the sensible air cooler. The water mist that has undergone heat and moisture exchange performs a secondary heat and moisture exchange with the air entering from the second air inlet at the first filler. The wind after the secondary heat and moisture exchange passes through the third water collector and the sensible air cooler and is discharged through the first fan unit; the heat exchanger receives the water transported by the water spray tray through the first channel and exchanges heat with the air entering from the third air inlet. The water transported by the second filler through the second channel exchanges heat and moisture with the air that has undergone heat exchange in the heat exchanger. After that, the wind that has undergone heat and moisture exchange exchanges heat and moisture with the water mist sprayed from the second nozzle and transported by the second water pump in the supercooling air cooler.

8. The three-stage cooling air cooler for use in a data center according to claim 7, characterized in that: The first water tray is provided with a water side communication port, and a water side overflow port is provided between the first water tray and the second water tray. When the water volume in the second water tray reaches a threshold, the water flows from the water side overflow port into the water side communication port.

9. The three-stage cooling air cooler for use in a data center according to claim 1, characterized in that: The fan assembly includes a first fan group and a second fan group, and the spray assembly includes a first water pump, a first nozzle, a second water pump, and a second nozzle; The controller is configured to: If the dry-bulb temperature is greater than the temperature critical value and the CO2 gas exhaust pressure is greater than the critical pressure, the sensible heat air cooler, condensing air cooler, subcooling air cooler, fan assembly, and spray assembly are controlled to execute the fourth cooling mode, wherein the temperature critical value is greater than the second temperature threshold.

10. The three-stage cooling air cooler for use in a data center according to claim 9, characterized in that: It also includes a first air inlet, a first water collector, a second air inlet, a first filler, a third water collector, a first water tray, a first nozzle, a water tray, a water distributor, a heat exchanger, a third air inlet, and a liquid outlet; The first nozzle is used to spray out the water delivered by the first water pump in the first water pan; the water pan includes a first channel and a second channel, the first channel is connected to the water distributor, and the second channel is connected to the second filler, and the first water pan is arranged at the bottom of the heat exchanger; When executing the fourth cooling mode, the controller is specifically configured to: Send an opening instruction to the fan assembly and the spray assembly to execute the fourth cooling mode. In the fourth cooling mode, external air enters from the first air inlet, cools in the sensible heat air cooler, and the cooled air passes through the condensing air cooler and is converted into CO2 liquid. The CO2 liquid enters the subcooling air cooler for dew point evaporation cooling and is discharged through the liquid outlet; external air enters from the first air inlet and exchanges heat and moisture with the water mist sprayed from the first nozzle on the surface of the condensing air cooler. The air that has undergone heat and moisture exchange passes through the first water collector and cools the sensible heat air cooler at the sensible heat air cooler. The CO2 gas in the device performs a secondary heat and moisture exchange with the water mist after heat and moisture exchange, and the air entering from the second air inlet at the first filler. The wind after the secondary heat and moisture exchange passes through the third water collector and the sensible heat air cooler and is discharged through the first fan unit; the heat exchanger receives the water transported by the water tray through the first channel, and exchanges heat with the air entering from the third air inlet. The water transported by the second filler through the second channel exchanges heat and moisture with the air undergoing heat exchange in the heat exchanger. The wind that has undergone heat and moisture exchange is in the supercooling air cooler and exchanges moisture with the water mist sprayed from the second nozzle transported by the second water pump.

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