Multi-stage liquid cooling system and arrangement

Abstract

A multi-stage liquid cooling system includes a first fluid inlet to receive a fluid to be cooled, a first air inlet to receive first air, a first air outlet to discharge the first air, a second air inlet to receive second air, and a second air outlet to discharge the second air. The heat recovery unit receives the second air from the main cooling unit and the fluid from the first fluid inlet, and cools the fluid in the first cooling phase. The cold water generation unit receives the first air from the first air inlet and the cooling fluid from the heat recovery unit, and further cools the fluid in the second cooling stage. The main cooling unit receives second air from the second air inlet and further cooled fluid from the cold water generating unit. The first air inlet and the second air inlet are located on the side, and the first air outlet is located on the top.

Description

[0001] This application claims priority to U.S. patent application No. 63 / 346,804, filed on May 27, 2022. Technical Field

[0002] The present application relates generally to multi-stage liquid cooling systems and configurations and, more particularly, to a multi-stage liquid cooling system configuration that combines evaporative cooling components with sensible cooling components with enhanced efficiency. Background Art

[0003] Evaporative cooling, also known as swamp cooling, uses the drop in air temperature that occurs when water changes state from liquid to gas to absorb energy. Evaporative coolers are useful in data centers, for example, where server or infrastructure heat loads are high and cannot be shut down frequently. In addition, evaporative coolers can be operated at a relatively low cost.

[0004] Since data centers use relatively large amounts of electricity and data centers are a rapidly growing market, there is a need for improved energy efficiency when cooling such data centers. Evaporative cooling is widely adopted due to its reliability in providing high efficiency, which can save a lot of costs and relatively reduce the energy footprint compared to traditional vapor compression systems. Evaporative cooling uses the latent heat of vaporization of water to achieve a reduction in water temperature close to the wet bulb temperature of the passing air, while increasing the moisture content and reducing the temperature of the circulating air. However, this advantage is limited by the ambient air humidity conditions, in this regard, it works best in hot and dry weather conditions, but not in humid climates without supplemental cooling equipment. Therefore, data center operators need to improve the efficiency of power usage in data centers. The energy efficiency of data centers should be improved by adopting alternative cooling technologies to supplement or replace the existing cooling infrastructure, thereby reducing the energy consumption of cooling equipment.

[0005] PCT / SG2022 / 05032 describes an efficient liquid cooling unit, which includes a cold-water generation unit (CGU) and a main cooling unit (MCU), wherein the cold-water generation unit is adapted to receive outdoor air from a first outdoor air inlet through a first airflow and cool water, and the main cooling unit is adapted to receive outdoor air from a second outdoor air inlet through a second airflow and cool the outdoor air received from the second outdoor air inlet. The cold-water generation unit includes a first evaporative medium, and the first evaporative medium is configured to circulate evaporative cooling water therein. Wherein, the airflow through the first airflow is separated from the airflow through the second airflow so that the multiple airflows do not mix with each other, and the main cooling unit and the cold-water generation unit are in fluid communication with the water management system through the first fluid flow. Although this design advantageously improves energy efficiency, known designs sometimes have the problem of exhaust gas from the heat recovery unit returning when being sent to the main cooling unit or the cold-water generation unit. Therefore, it is necessary to design an improved liquid cooling device that reduces problems associated with short circuits while reducing the amount of physical space occupied by the entire system. Summary of the invention

[0006] According to a first aspect, a multi-stage liquid cooling system comprises a top, a bottom and a plurality of sides connecting the top to the bottom. The multi-stage liquid cooling system comprises: a first fluid inlet adapted to receive a hot fluid to be cooled, a first air inlet adapted to receive a first air, a first air outlet adapted to discharge the first air and a second air inlet adapted to receive a second air, so that the second air is isolated from the first air in the multi-stage liquid cooling system; a second air outlet adapted to discharge the second air, a heat recovery unit, a cold water generation unit and a main cooling unit. The heat recovery unit is adapted to receive the second air from the main cooling unit and the fluid from the first fluid inlet, and cool the fluid in the first stage. The cold water generation unit is adapted to receive the first air from the first air inlet and the cooling fluid from the heat recovery unit, and further cool the fluid in the second stage. The main cooling unit is adapted to receive the second air from the second air inlet, further cooling the fluid from the cold water generation unit, and further cool the fluid in the third stage. The first air inlet and the second air inlet are respectively located at the side, and the first air outlet is located at the top.

[0007] From the foregoing disclosure and the following more detailed description of various embodiments, it will be apparent to those skilled in the art that the present application provides a significant advancement in evaporative cooler technology. Of particular importance in this regard is the potential for improved energy efficiency and reduced risk of short circuiting, in which hot exhaust gases are inadvertently reintroduced into the evaporative cooler. Additional elements and advantages of various embodiments will be better understood in light of the detailed description provided below. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of a multi-stage liquid cooling system according to an embodiment is shown, wherein a cold water generating unit (CGU) and a main cooling unit (MCU) are separated by an air flow divider;

[0009] Figure 2 shows a schematic diagram of a multi-stage liquid cooling system according to another embodiment, wherein the CGU is located above the MCU;

[0010] Figure 3 A schematic diagram showing another embodiment of a multi-stage liquid cooling system, wherein one or more first air exhaust outlets and one or more second air outlets are located at the top of the cooler;

[0011] Figure 4 Shows Figure 3 The fluid trajectory of the embodiment;

[0012] Figure 5 A schematic plan view of the top of a multi-stage liquid cooling system is shown, wherein a pair of first and second air outlets are shown;

[0013] Figure 6 A schematic plan view of the top of an embodiment of a multi-stage liquid cooling system is shown, wherein four first air outlets and second air outlets are shown;

[0014] Figure 7 A schematic plan view of the top of an embodiment of a multi-stage liquid cooling system is shown, wherein six first air outlets and second air outlets are shown.

[0015] It should be understood that the drawings are not necessarily drawn to scale, but rather represent various features that illustrate the basic principles of the present application in a somewhat simplified manner. The specific design features of the multi-stage liquid cooling system disclosed in the present application (e.g., the specific dimensions of the inlet and the specific dimensions of the outlet) will be determined in part by the specific intended application and use environment. Certain features of the illustrated embodiments have been enlarged or deformed relative to other features to help provide a clear understanding. Specifically, for example, thin features can be thickened for clarity of illustration. Unless otherwise stated, all references to directions and positions refer to the directions shown in the figures. DETAILED DESCRIPTION

[0016] It will be apparent to those skilled in the art, i.e., those having knowledge or experience in the art, that the multi-stage liquid cooling system disclosed in the present application may have a variety of uses and design variations. The following detailed discussion of various alternative components and embodiments will illustrate the general principles of the present application with reference to a multi-stage liquid cooling system including improved energy efficiency. Other embodiments suitable for other applications will be apparent to those skilled in the art with the benefit of this application.

[0017] The multi-stage liquid cooling system described in this application can be used in series with other equipment, such as a key cooling system or a supplementary cooling system in a data center. By combining different configurations of fluid paths in the cooling system, it can provide a comprehensive set of cooling solutions with different efficiencies to adapt to different environmental conditions and load requirements.

[0018] Now referring to the accompanying drawings, Figure 1 1 shows a multi-stage liquid cooling system 100 according to an embodiment, which includes a cold water generation unit (CGU) 102, a main cooling unit (MCU) 114 and a heat recovery unit (HRU, heat recovery unit) 112. A relatively hot fluid is supplied to the cooling system 100 via a fluid inlet 81 (such as Figure 4 The liquid flows into the cooler 100 (as shown) and passes through a series of heat transfer steps (through the first heat exchanger 108 to the first evaporative medium 104 to the second evaporative medium 106 to the second water tank 118). For example, a representative temperature reduction of the liquid can be from a temperature of about 31°C at the fluid inlet to about 30°C at the first heat exchanger 108, to about 28°C to 29°C at the first evaporative medium 104, and to about 26°C at the second evaporative medium 106. The multi-stage liquid cooling system shown includes a bottom wall 160, a top wall 150, and side walls 152, 154 that operably connect the bottom wall to the top wall. The airflow divider 120 located in the cooler cooperates with one or more walls to separate the cold water generation unit (CGU) 102 from the main cooling unit (MCU) 114 and the heat recovery unit (HRU) 112. The multi-stage liquid cooling system also shows at least one first fan 122, at least one second fan 124, a first water tank 116 located in the CGU, and a second water tank 118 located in the MCU. The CGU 102 also includes a first evaporative medium 104 for evaporative cooling water circulation. The side wall 154 includes a first air inlet 71, and the top wall 150 includes a first air outlet 79. The first fan 122 draws air from the inlet 71, passes it through the first evaporative medium 104, and discharges the heated air through the outlet 79. Advantageously, the first fan 122 in the CGU 102 is arranged to cause air to leave the first evaporative medium 104 in an upward direction and away from the second air inlet 91. The side wall in this embodiment may include an upper side portion 152 and a lower side portion 153 on the left side (e.g., Figure 1 ), the right side portion includes an upper side portion 154 and a lower side portion 155 (as shown Figure 115). The second air inlet is shown on one of the plurality of side walls 152 at the MCU below the airflow divider. Typically, the plurality of side walls are perpendicular to the bottom wall 160 and the top wall 150, and may include, for example, four side walls and a rectangular cross-section. The second air is isolated from the first air in the multi-stage liquid cooling system. That is, the two air flows follow different paths in the multi-stage liquid cooling system until each air flow reaches a separate outlet.

[0019] The main cooling unit MCU 114 includes a second evaporative medium 106 for evaporatively cooling the water / fluid circulating therein, and is provided with a second heat exchanger 110. The heat recovery unit HRU 112 is provided with a first heat exchanger 108. A second fan 124 is used to move air from the second air inlet 91 to the second air outlet 99 via the MCU 114 and the HRU 112. The first water tank 116 and the second water tank 118 may include containers for containing water circulating in the multi-stage liquid cooling system 100. A water pump for circulating the fluid / water is usually provided. The airflow separator 120 is used to separate the first airflow in the CGU 102 from the second airflow of the MCU 114 and the HRU 112. As shown below Figure 4 As discussed in more detail in , the MCU 114 and the CGU 102 are arranged in fluid communication.

[0020] exist Figure 1 In an embodiment, the CGU 102 is located next to the MCU 114 (located below the HRU 112), so that the CGU is located between the side wall 154 and the airflow divider 120. The total height of the CGU 102 can be equal to the total height of the MCU 114 and the HRU 112, so that the multi-stage liquid cooling system 100 fully utilizes the available headroom while reducing the amount of physical space occupied. Figure 1 As shown, the first water tank 116 is located below the CGU 102, and the second water tank 118 is located below the MCU 114. Components such as the first water tank 116, the second water tank 118, the CGU 102, and the MCU 114 can be arranged in a variety of ways. The first fan 122 and the second fan 124 (including the corresponding air outlets) can be arranged as shown. Figure 1 In the arrangement shown, the first fan outlet is located on the top wall and the second fan outlet is located on the side wall 152. More generally, the fan outlets are usually located away from the air inlet. Alternatively, all fan outlets can be located on the top wall and can adopt one of several different geometric shapes - for example, a shape similar to a polygonal prism including four vertical faces, six vertical faces, or eight vertical faces. The first fan 122 in the CGU 102 can be located above the first evaporative medium 104 so that the air leaves the first evaporative medium 104, that is, the airflow (airflow 1) is as follows Figure 1The net upward direction towards the top is shown. This configuration is more advantageous than horizontal airflow directions or downward airflow directions because it reduces the chance of water droplets being sucked in with the airflow, thereby reducing water lift and eliminating the need for eliminators. This configuration also allows the air surface velocity through the evaporative medium to be higher than the other two flow directions, thereby facilitating a reduction in the total surface area and, therefore, the overall footprint of the unit.

[0021] A first water tank 116 is located at the bottom of the CGU 102, which collects water flowing out of the first evaporative medium 104 in the CGU 102 and then pumps it to the next stage of the cooling process, the second evaporative medium 106 of the MCU 114. In this embodiment, a pump may be located in the first water tank 116 to circulate water to the MCU 114. Some of the water flows directly to the second water tank 118 located below the MCU 114. In another embodiment, all of the water from the CGU 102 passes through the second evaporative medium 106 of the MCU 114, so that all of the water is cooled to a lower temperature after passing through the MCU unit 114. The first water tank 116 and the second water tank 118 may not be directly fluidly connected to achieve a lower final water temperature. As shown in the embodiment of the present application, an internal second fluid flow can be provided, and the internal second fluid flow flows from the second water tank 118 to the second heat exchanger 110, then flows to the first evaporation medium 104, flows from the first evaporation medium 104 to the first water tank 116, flows from the first water tank 116 to the second evaporation medium 106, and then returns to the second water tank 118. This second fluid flow allows the second air / second airflow to be precooled first in the second heat exchanger 110, so that when it contacts the water at the second evaporation medium 106, the final water temperature leaving the second evaporation medium can be significantly reduced. The second airflow after the first evaporation medium is in a net upward direction toward the top.

[0022] The MCU 114 is located at the side wall 153 adjacent to the CGU 102 and is separated by the airflow divider 120 and is located below the airflow divider 120. This arrangement helps to reduce airflow leakage between the CGU 102 and the MCU 114. Below the MCU 114 is a second water tank 118 located at or near the bottom wall 160, which collects water from the second evaporative medium 106 in the MCU 114. The final cold water is collected in the second water tank 118 and circulated to an external device that uses the cold water by an external pump or gravity feed depending on the application. There is also another circulation pump in the second water tank 118, which is used to circulate the generated cold water to the second heat exchanger 110 of the MCU 114 to pre-cool the air and then flow to the first evaporative medium 104 in the CGU 102 for regeneration.

[0023] exist Figure 1In the embodiment of the present invention, in the main cooling unit 114, the second heat exchanger 110 is located at the second air inlet 91 as being located upstream of the second evaporative medium 106. The function of the second heat exchanger 110 is to pre-cool the ambient air sucked in by the second fan 124 through the second inlet 91 so that the air temperature of the second airflow is reduced before being delivered to the second evaporative medium 106. This has the effect of cooling the water in the second evaporative medium 106 to below the ambient wet bulb temperature. Preferably, the size ratio of the second heat exchanger 110 to the second evaporative medium 106 is 1:1 so that the capacity of the second heat exchanger 110 and the capacity of the second evaporative medium 106 remain uniform. Optionally, the size ratio can be changed to increase or decrease the cooling capacity of each component to meet the cooling requirements. Specifically, if the size of the second evaporative medium 106 is larger than the size of the second heat exchanger 110, the temperature of the water entering the second water tank 118 is even lower, and more water can also flow to the second evaporative medium 106. If the size of the second heat exchanger 110 is larger than the size of the second evaporative medium 106, the air temperature leaving the second heat exchanger 110 is relatively low, allowing the water temperature to be lower despite the lower flow rate.

[0024] exist Figure 1 In the embodiment of the present invention, the HRU 112 is located above the MCU 114 that houses the heat exchanger 108. As shown, the HRU is located above the MCU and above the airflow divider 120, generally adjacent to the side wall 152, so that the overall size of the heat exchanger 108 is similar to the size of the second heat exchanger 110 in the MCU 114. This arrangement helps to maintain the surface velocity of the fluid flowing through the heat exchanger, improving cooling performance. The first heat exchanger 108 in the HRU 112 allows the return hot water supplied by the liquid cooling device 100 to be partially regenerated by pre-cooling using the cold air partially generated from the MCU 114, and then circulating the water to the CGU 102 for further cooling and regeneration. The cooling capacity loss is low, and the cold air generated as a byproduct of cooling the water in the MCU 114 is recycled to cool the heated water, thereby reducing the regeneration required in the CGU 102 and allowing the size of the CGU 102 to be further reduced.

[0025] The second air fan 124 is located between the MCU 114 and the HRU 112 unit, so that the MCU 114 is located upstream of the fan 124 and the HRU 112 is located downstream. This orientation saves a lot of space, and the fan 124 occupies the unused space in the center of the HRU 112, while maintaining a net upward airflow direction of the air present in the MCU second evaporative medium 106, i.e., airflow 2 (as shown in FIG. Figure 1112). Thus, the exhaust is exhausted from the periphery of the HRU 112 and returned to the surrounding environment. In another embodiment, the fan 124 is located either upstream of the MCU 114 and the HRU 112, or downstream of the MCU 114 and the HRU 112, without any significant performance changes. Although the second air outlet 99 can be generally located near the side wall 152, the second air outlet 99 can also be extended away from the side wall through additional ducts or separators to keep the exhaust away from the air inlet. The second fan 124 is located downstream of the second evaporative medium 106 to form a more uniform surface velocity distribution on the second evaporative medium 106, which helps to improve the heat transfer efficiency of the entire second evaporative medium 106.

[0026] Figure 2 Another embodiment of a multi-stage liquid cooling system 200 is shown, wherein the CGU 202 is located directly above the HRU 212, between the side walls 252 and 254 and between the top wall 250. The CGU 202 is located above the HRU 212, which in turn is located above the MCU 214. The first fan 222 and the second fan 224 and the first water tank ( Figure 2 214 and the HRU 212. The first water tank 218 and the second water tank 218 may also be arranged in a variety of ways. Since all components are stacked on top of each other, the amount of physical space occupied is reduced, thereby providing a tall and streamlined embodiment. Therefore, the airflow separator 220 is placed below the CGU 202 to separate the airflow flowing in the CGU 202 from the airflow flowing in the MCU 214 and the HRU 212. Similar to the first structure, the first water tank can be placed at the bottom of the CGU 202, using gravity to collect water supplied to the first evaporative medium 204, and then further flow it to the second evaporative medium 206 in the MCU 214. Moreover, in the second structure, no water pump is required in the first water tank, thereby saving cost and energy.

[0027] In this embodiment, the second fan 224 is used to extract air from the second air inlet 291 and move the air from the MCU 214 to the HRU 212, and can be placed between the MCU 214 and the HRU 212 to reasonably utilize the space. In order to overcome the problem of exhaust gas from the HRU 212 short-circuiting back to the MCU 214 or the CGU 202, the size of the first heat exchanger 208 and / or the second heat exchanger 210 in the HRU 212 is reduced to increase the effective surface velocity or introduce additional ducts or separators to keep the exhaust gas away from the air intake. Further, the position of the second fan 224 can be relocated so that the short-circuiting of the exhaust gas is kept at a low level without reducing the surface area of ​​the heat exchanger or introducing additional air separators.

[0028] Figure 3Another embodiment of a multi-stage liquid cooling system 300 is shown, wherein the CGU 302 is located above the MCU 314, and the HRU 312 is located in a central position away from the side walls 352, 353 and 354, 355. The figure shows that the HRU is at least partially surrounded by the CGU 302 and the MCU 314, so that the cavity created by the surrounding components of the MCU 314 is used to accommodate the HRU 312 components. The relative position of the first heat exchanger 308 of the HRU allows it to be higher than the MCU components, that is, at least a portion of the first heat exchanger 308 is closer to the top wall 350 than the second heat exchanger 310, thereby ensuring a net upward flow of air through the second evaporative medium 306, and ensuring that the size of the evaporative medium can be kept low to reduce the amount of physical space occupied. The first heat exchanger 308 can be configured to be at a certain angle to further increase the use of the cavity space to accommodate the components and meet a smoother airflow transition from one component to the next. As shown, the sides are perpendicular to the top and bottom so as to be approximately vertically aligned during normal operation, and the first heat exchanger 308 is positioned at an acute angle relative to the sides. This configuration advantageously reduces the size of the multi-stage liquid cooling system. Similarly, in this configuration, the second fan 324 is placed downstream of the MCU 314 and HRU 312 and is located on the top wall of the device 300 so that air passing through these two components is exhausted in an upward direction at the outlet 399 to prevent any recirculation back into the device, whether through the air inlet of the first air / airflow 1 or the air inlet of the second air / airflow 2. The first air outlet 379 can be located at a portion of the top 360 that forms an acute angle with the side 352 / 354. As shown Figure 3 As shown, the first fan 322 can be at about 45 degrees to the side wall. The first air inlet is located on the first side wall opposite to the second side wall, and the second air inlet is also located on the first side wall. Figure 3 In the embodiment, the first side wall is 354 / 355 and the second side wall is 352 / 353. The first air inlet 371 is located at 354 and the second air inlet 391 is located at 355. The two side walls may be substantially perpendicular to the top wall 350 and the bottom wall 360.

[0029] Figure 4 Shows Figure 3Embodiments, wherein there is a trace of a water circuit. The fluid in the first fluid stream enters the multi-stage liquid cooling system at the fluid inlet 81, which is typically located on one of the multiple side walls. From there, the fluid passes through a series of heat transfer steps. First, the first heat exchanger 308 in the HRU, and then flows from there to the first evaporative medium 304, which is shown in this embodiment, at least partially located above the first heat exchanger 308 (i.e., closer to the top wall 350). From there, the fluid can flow to the second evaporative medium 306 and then collect in the second water tank 318. From there, the cooling water can be exported from the multi-stage liquid cooling system. The configuration of the HRU relative to the MCU and CGU advantageously reduces the water lift of the first evaporative medium 306 and the water lift of the second evaporative medium 304, and increases the surface velocity to achieve a compact system. The amount of physical space occupied. The airflow divider 320 separates the airflow in the CGU 302 from the airflow in the MCU 314 and the HRU 312, so that two independent airflows are driven by different fans 322, 324. Figure 3 to Figure 4 The embodiment shown in allows for enhanced control and flexibility of the two airflows, thereby allowing for individual control of the capacity of the CGU 302, the capacity of the MCU 314, and the capacity of the HRU 312. This embodiment allows for flexibility in the variable capacity multi-stage liquid cooling system in different operating modes, thereby reducing power consumption, i.e., a few components of the liquid cooling device 300 are not operated to reduce power consumption. For example, if the cooling capacity generated by the CGU 302 is sufficient to meet the application requirements, the second fan 324 for the MCU 314 and the HRU 312 is not operational, thereby providing additional power savings. Similarly, the MCU 314 and the HRU 312 can also be operated separately without the CGU 302 being operated.

[0030] As shown in the embodiment of the present application, an internal second fluid flow may be provided, which flows from the second water tank 318 to the second heat exchanger 310, then to the first evaporative medium 304, from there to the first water tank 316, from there to the second evaporative medium 306 and back to the second water tank 318. The second fluid flow allows the second airflow to be first precooled in the second heat exchanger 310, so that when it contacts the water at the second evaporative medium 306, the final water temperature leaving the second evaporative medium can be significantly reduced.

[0031] like Figure 3 and Figure 4As shown, the airflow divider 320 is placed to separate the airflow flowing in the CGU 302 from the airflow of the MCU 314 and the HRU 312. Since the first heat exchanger 308 is at an acute angle relative to the vertical direction (i.e., perpendicular to the plane formed by the bottom and / or top wall), the airflow divider can also be in an inclined position to help smooth the airflow within the system and eliminate any dead spots. The first fan 322 of this embodiment is also placed above the first evaporative medium 304 of the CGU 302 (closer to the top wall than the first evaporative medium 304) and the top of the multi-stage liquid cooling system 300, so that the exhaust air is upward and away from the equipment air intake.

[0032] Similar to the first and second embodiments, Figure 3 and Figure 4 In the embodiment of the present invention, the air outlet 379, 399 can include any number of sides for air intake. The first air inlet and the second air inlet can be located on the same side or different sides. Figure 5 An example is shown that can be used with any of the embodiments described above. Figure 5 314 and 312. The multi-stage liquid cooling system disclosed herein may include a generally rectangular cross-section at least near the top wall.

[0033] Figure 6 FIG. 1 shows a plan view of another exhaust fan arrangement, wherein four first fans 322 are positioned at 90° intervals around a second fan located in the center. Figure 5 As in the embodiment of the present invention, all fans are located on the top wall, and the portions may not necessarily be uniformly flat. The air divider 320 is shown to partially isolate the CGU from the MCU / HRU. The multi-stage liquid cooling system disclosed in the present application may have a substantially square cross-section at least near the top wall. Multiple first exhaust fans 322 can advantageously disperse relatively hot exhaust gas and further reduce potential problems of short circuits. Since the first air outlet corresponds to the first fan, when there are four first fans, there are four first air outlets positioned circumferentially around the second air outlet.

[0034] Figure 7 FIG. 1 shows a plan view of another exhaust fan arrangement. Six first fans 322 are located on the top wall at 60° intervals, circumferentially surrounding a second fan 324 located in the center. Figure 5 and Figure 6 As in the embodiment of the present invention, all fans are located on the top wall, and portions of the top wall may not necessarily be uniformly plane. The air divider 320 is shown to partially isolate the CGU from the MCU / HRU. The multi-stage liquid cooling system disclosed in the present application may include a roughly hexagonal cross-section at least near the top wall. Multiple first exhaust fans 322 can advantageously disperse relatively hot exhaust gas and further reduce potential problems of short circuits. Since the first air outlet corresponds to the first fan, when there are six first fans, there are six corresponding first air outlets, and these first air outlets can be positioned on the top circumferentially and equidistantly around the second air outlet.

[0035] The liquid cooling device 300 includes a cold water generating unit (CGU) 302, a heat recovery unit (HRU) 312, a main cooling unit (MCU) 314, water tanks 316, 318, fans 322 and 324 for moving the first air flow and the second air flow respectively, a circulating water pump and an air flow separator 320 to separate the air flow in the cold water generating unit 302 from the main cooling unit 314 and the heat recovery unit HRU 312. The fluid flows through the multi-stage liquid cooling system disclosed in the present application to cool the circulating water to below the ambient wet bulb temperature, which may include a multi-stage cooling process. In the first stage, the first fluid from warm to hot is introduced into the multi-stage liquid cooling system at the fluid inlet 81, so that the first fluid passes through the first heat exchanger 308 located in the HRU and exchanges heat with the second air flow there to cool the fluid. From there, in the second stage, the fluid flows to the first evaporative medium 304 located in the CGU, where it exchanges heat with the first air flow, further reduces the temperature of the fluid, and is collected in the first water tank 316. In the third stage of heat transfer, the fluid is transferred to the MCU and the second evaporative medium 306 and exchanges heat with the second airflow to cool the fluid for a third time. Once the third stage is completed, the cooled fluid is collected in the second water tank 318 and is eventually pumped or otherwise delivered to an outlet for use, such as for cooling data centers and other places that require a lot of cooling. Water can drip from the second evaporative medium 306 or otherwise be operably connected to the second water tank with the second evaporative medium 306, so no direct physical connection is required.

[0036] The ability to cool water to a sufficiently low temperature (in this case, close to or below the wet bulb temperature) and then send it out to provide cooling is beneficial in reducing cooling loads and reliance on traditional cooling technologies (such as refrigerants and chilled water, which rely on compressors to run and are energy-intensive). For example, in a data center, heat from a data platform is traditionally transferred to chilled water running in a cooling unit or fan coil unit. With the invention disclosed in the present application, chilled water can also be sent to the fan coil unit and absorb some of the heat load (for example, about 40% to 50% of the total load), so that less load needs to be cooled by chilled water running on compressors. Therefore, advantageously, the multi-stage liquid cooling system disclosed in the present application can help data centers reduce their power consumption and the costs that come with it. From the foregoing disclosure and detailed description of certain embodiments, it is apparent that various modifications, additions, and other alternative embodiments are possible without departing from the true scope of the present application. The embodiments discussed are selected and described to provide the best explanation of the principles of the present application and its practical application, so that ordinary technicians in the field can use the present application in various embodiments and various modifications to suit the specific purposes envisioned. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

1. A multi-stage liquid cooling system comprising a top portion, a bottom portion, and a plurality of sides connecting the top portion to the bottom portion; The multi-stage liquid cooling system comprises: a first fluid inlet adapted to receive a hot fluid to be cooled; a first air inlet adapted to receive first air, and a first air outlet adapted to discharge the first air; a second air inlet adapted to receive second air such that the second air is isolated from the first air, and a second air outlet adapted to exhaust the second air; heat recovery unit, cold water generation unit and main cooling unit; Characterized in that the heat recovery unit is adapted to receive the second air from the main cooling unit and the fluid from the first fluid inlet, and cool the fluid in a first stage; the cold water generating unit being adapted to receive the first air from the first air inlet and the cooling fluid from the heat recovery unit and further cool the fluid in a second stage; the primary cooling unit being adapted to receive the second air from the second air inlet, further cooling fluid from the cold water generating unit, and further cooling fluid in a third stage; and The first air inlet and the second air inlet are respectively located at the side portions, and the first air outlet is located at the top portion.

2. The multi-stage liquid cooling system according to claim 1, characterized in that: The second air outlet is also located at the top.

3. The multi-stage liquid cooling system according to claim 1, characterized in that: There are at least two first air outlets.

4. The multi-stage liquid cooling system according to claim 3, characterized in that: The second air outlet is centrally located at the top between at least two of the first air outlets.

5. The multi-stage liquid cooling system according to claim 3, characterized in that: There are at least four first air outlets, and the at least four first air outlets are circumferentially positioned around the second air outlet.

6. The multi-stage liquid cooling system according to claim 1, characterized in that: The second air inlet and the second air outlet are located on the same side.

7. The multi-stage liquid cooling system according to claim 6, characterized in that: The first air inlet and the second air inlet are located on the same side.

8. The multi-stage liquid cooling system according to claim 1, characterized in that: The side portion includes a first side wall and a second side wall opposite to the first side wall, and the first air inlet and the second air inlet are both located on the first side wall.

9. The multi-stage liquid cooling system according to claim 1, characterized in that: The top portion includes a portion forming an acute angle with at least one of the side portions, and the first air outlet is located on the portion.

10. The multi-stage liquid cooling system according to claim 1, characterized in that: The heat recovery unit comprises a first heat exchanger adapted to transfer heat from a first fluid to the second air.

11. The multi-stage liquid cooling system according to claim 1, characterized in that: The cold water generating unit comprises a first evaporative medium adapted to transfer heat from a first fluid to the first air.

12. The multi-stage liquid cooling system according to claim 11, characterized in that: The first fan is located closer to the top than the first evaporative medium.

13. The multi-stage liquid cooling system according to claim 11, characterized in that: The direction of air flow after the first evaporative medium is in an upward direction toward the top.

14. The multi-stage liquid cooling system according to claim 1, characterized in that: The primary cooling unit comprises a second evaporative medium adapted to transfer heat from the first fluid to the second air.

15. The multi-stage liquid cooling system according to claim 14, characterized in that: The direction of air flow after the second evaporative medium is in an upward direction toward the top.

16. The multi-stage liquid cooling system according to claim 14, characterized in that The multi-stage liquid cooling system further includes a second heat exchanger located in the main cooling unit, the second heat exchanger being located between the second air inlet and the second evaporative medium.

17. The multi-stage liquid cooling system according to claim 1, characterized in that: The multi-stage liquid cooling system further includes an air flow divider that separates the first air from the second air and separates the cold water generating unit from the heat recovery unit.

18. The multi-stage liquid cooling system according to claim 1, characterized in that: The side is perpendicular to the bottom, and the first heat exchanger is positioned at an acute angle relative to the side in the heat recovery unit.

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