Cooling system and electronic rack with multiple phase change circuits

Abstract

The present disclosure provides a cooling system and an electronic rack having multiple phase change circuits. The cooling system includes an evaporator, which is connected to a first condenser, a second condenser, a compressor, and a thermal expansion valve through a fluid pipeline. One or more valves are arranged in the fluid pipeline. The one or more valves are operated to circulate the fluid between the evaporator and the first condenser in a first mode; in a second mode, the fluid is circulated between a) the evaporator and the first condenser and b) the evaporator, the second condenser, and the thermal expansion valve, and in a third mode, the fluid is circulated between a) the evaporator and the first condenser and c) the evaporator, the compressor, the second condenser, and the thermal expansion valve.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to cooling systems for information technology (IT) equipment and more particularly to cooling systems having multiple phase change loops. Background Art

[0002] Data centers are mission-critical facilities that house a large number of servers and IT equipment. The cooling system provides the proper thermal environment for the IT equipment. The key is to design a cooling system that provides cooling of the IT equipment under various heat load conditions in an efficient and durable manner.

[0003] Phase change cooling technology tends to have good heat transfer performance while maintaining low temperatures. Passive phase change cooling uses gravity to drive the fluid without the need for a pump. Due to the inherent instability of the phase change process, controlling a passive phase change cooling system and maintaining a stable state of the passive phase change cooling loop can be a challenge. Summary of the invention

[0004] In a first aspect, there is provided a cooling system comprising:

[0005] an evaporator connected to the first condenser, the second condenser, the compressor, and the thermal expansion valve through fluid lines; and

[0006] one or more valves disposed in the fluid line, the one or more valves being operated to circulate fluid between the evaporator and the first condenser in a first mode,

[0007] In a second mode, a fluid is circulated between a) the evaporator and the first condenser and b) the evaporator, the second condenser and the thermal expansion valve, and

[0008] In a third mode, a fluid is circulated between a) the evaporator and the first condenser and c) the evaporator, the compressor, the second condenser, and the thermal expansion valve.

[0009] In a second aspect, an electronic rack is provided, comprising:

[0010] IT equipment; and

[0011] A cooling system is thermally coupled to the IT equipment, wherein the cooling system is the cooling system as described in the first aspect.

[0012] The cooling system according to the present invention can operate in an energy efficient and healthy mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Embodiments of the invention are illustrated by way of example and not limitation in the figures of the accompanying drawings in which like references indicate similar elements.

[0014] Figure 1 A cooling system with more than one phase change circuit is shown according to one embodiment.

[0015] Figure 2 A process for controlling a cooling system according to one embodiment is shown.

[0016] Figure 3 A switching buffer according to one embodiment is shown.

[0017] Figure 4 A cooling system with more than one phase change circuit is shown according to one embodiment.

[0018] Figure 5 A cooling system with multiple backup condensers is shown according to one embodiment.

[0019] Figure 6 An electronics rack chassis is shown according to one embodiment. DETAILED DESCRIPTION

[0020] Various embodiments and aspects of the present invention will be described with reference to the details discussed below, and the accompanying drawings will illustrate various embodiments. The following description and drawings are illustrative of the present invention and should not be construed as limiting the present invention. Many specific details are described to provide a thorough understanding of various embodiments of the present invention. However, in certain cases, in order to provide a concise discussion of embodiments of the present invention, known or conventional details are not described.

[0021] References in the specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. The phrase "in one embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment.

[0022] Embodiments of the present disclosure solve problems with existing cooling solutions, such as, for example, those mentioned above. In the present disclosure, a control and switch architecture for managing a cooling system is described. The cooling system includes multiple phase change loops, including a mix of active and passive loops.

[0023] The cooling system controls its own two-phase thermal system and operates in an energy efficient and healthy mode (e.g., taking precautions to maintain the integrity of the system and its parts). An active phase change cooling loop is integrated with a passive phase change cooling loop with pressure control for low, medium and high heat generation sources. The cooling system can use a switching scheme with a variation buffer on the control parameters (e.g., pressure thresholds) to ensure that the cooling system (including the compressor) operates in an energy efficient manner while also improving the stability and reliability of the system.

[0024] According to one embodiment, Figure 1 As shown, the cooling system 100 includes an evaporator 120, which is connected to a first condenser 102, a second condenser 104, a compressor 108 and a thermal expansion valve 116 through a fluid line. One or more valves 106 are arranged in the fluid line to coordinate the flow of fluid from the evaporator to the condenser and the compressor. One or more valves are operated to circulate the fluid between the evaporator and the first condenser in a first mode ("passive mode"). In this mode, the flow to the compressor and the second condenser is restricted.

[0025] The evaporator and the first condenser can form a thermosiphon loop that circulates passively between the evaporator and the first condenser without the use of a motor / pump. In this case, the fluid in the cooling system is evaporated in the evaporator. The evaporated fluid flows to the first condenser based on natural convection (using thermal expansion) to create a density difference across the loop. The evaporated fluid floats from the evaporator to the first condenser. The cooler fluid will sink from the first condenser back to the evaporator. Thus, the fluid circulates without a pump while transferring thermal energy away from the heat source (e.g., IT equipment). This allows the cooling system to work passively when less heat transfer is required.

[0026] In a second mode ("conversion mode"), one or more valves are operated to circulate fluid between a) the evaporator and the first condenser and b) the evaporator, the second condenser, and the thermal expansion valve. Similar to the first mode, this second mode does not use a motor / pump. In both the first and second modes, the thermal expansion valve is controlled to maintain no pressure drop across the thermal expansion valve 116 - no pressure is released by the thermal expansion valve in these modes.

[0027] In the third mode ("extreme mode"), one or more valves are operated to circulate the fluid between a) the evaporator and the first condenser and c) the evaporator, the compressor, the second condenser and the thermal expansion valve. In this mode, the compressor 108 and its motor / pump are turned on by the motor controller 110. The compressor greatly increases the pressure and temperature of the fluid through compression. There is no significant phase change from the inlet to the outlet of the compressor. Due to the threshold temperature required to enter the third mode, all the coolants in the compressor should be steam (gas). Then, the second condenser extracts a large amount of this heat energy from the fluid, converting some (if not all) of the evaporated fluid into liquid form. In the third mode, due to the increase in active compression and circulation of the fluid, more heat energy is extracted at the second condenser than in other modes. In some embodiments, the compressor is an adjustable compressor. The frequency of the compressor can be adjusted, for example, by motor control and / or controller to provide a variable cooling capacity. At higher frequencies, the cooling system is able to extract more heat energy from the heat source.

[0028] In this third mode, the thermal expansion valve 116 is controlled to greatly reduce the pressure and temperature of the fluid (e.g., coolant). There is no phase change from its inlet to its outlet. All coolant is liquid. The pressure difference across the thermal expansion valve can be controlled (e.g., by a controller unit, using control commands). As discussed, when the compressor is not operating (e.g., bypassed in the first and second modes), there is no pressure difference before and after the thermal expansion valve by control. When the compressor is operating, the temperature and pressure of the fluid are reduced at the outlet of the thermal expansion valve. In the third mode, the controller determines how much to reduce the pressure (e.g., "reduce pressure by X amount") and can control the reduction to different pressures by analog or digital control commands. The reduction command can be determined based on the pressure at P4.

[0029] The system includes a pressure sensor 124, which is arranged in the cooling system to measure the pressure in the fluid pipeline at positions P1, P2, P3 and P4. One or more pressure sensors in the compressor 108 sense the pressure P1, thereby monitoring the working state of the compressor-to determine whether the compressor is compressing the fluid. Pressure sensors P3 and P2 sense the pressure at the inlet and outlet of the compressor, thereby monitoring the suction pressure and discharge pressure of the compressor. P1 monitors the pressure inside the compressor. If one or more of the pressures P1, P2 or P3 are too low (e.g., below a threshold pressure), this indicates that the compressor is not working properly and / or there is too much liquid in the compressor. In this case, the control unit and / or the motor control can stop the compressor from running to prevent damage to the compressor and / or the cooling system. The motor control can be implemented as a combination of hardware (e.g., programmable logic, electronic circuits, electrical switches and relays, and / or processors) and software (instructions stored in a machine-readable memory), and the pressure sensor measures the outlet pressure of the evaporator P4, for example, on one side of the three-way valve. This pressure can be used by the cooling system to monitor the coolant flowing out of the evaporator.

[0030] When the cooling system is operated in the third mode, the fluid can be measured at or before the inlet of the evaporator, or between the evaporator and the thermal expansion valve. The amount of the fluid in the form of steam is measured. This amount can be described as a percentage, a ratio or a volume. This measurement can be performed using a flow meter 114 or a cooling system. The flow meter can be an ultrasonic flow meter that generates one or more signals, and the signal indicates how much fluid is in the form of steam. Steam measurement can be performed using other equivalent technologies. Based on the measurement of the amount of fluid in the form of steam at the inlet of the evaporator, one or more valves are operated to increase the fluid circulation (i.e., through the limit mode loop) from the evaporator to the compressor and the second condenser.

[0031] It should be understood that each of the evaporator, condenser and valve has an inlet and an outlet. The inlet is shown with an arrow pointing to the fluid line inside the corresponding component, and the outlet is shown with an arrow pointing to the fluid line outside the corresponding component. The condenser of any one of the cooling system embodiments can be a liquid-cooled or air-cooled condenser. The fluid in the fluid line can be a coolant (e.g., water, ethylene glycol, etc.), which can be in liquid or vapor (gas) form.

[0032] The cooling system automatically switches between the first mode, the second mode, and the third mode based on the pressure P4, which can be described as the pressure in the fluid line at the outlet of the evaporator. The controller unit 122 can monitor the pressures P1-P4 and control each of the one or more valves 106 in a coordinated manner to guide and limit fluid circulation, as described in the first, second, and third modes. The controller unit 122 may include one or more processors that execute programming instructions stored on a machine-readable medium. Additionally, or alternatively, the controller unit may include electronic hardware logic, such as a field programmable gate array (FPGA), a complex programmable logic device (CPLD), or other equivalent technology. The controller unit may be integrated into one or more valves, may be separately packaged as an independent device, and / or may be a combination of multiple devices.

[0033] One or more valves may be electromechanically controlled by the controller unit. For example, the valve may have an actuator (e.g., a solenoid and a magnetically attractable member) that opens and closes the valve when activated and deactivated. Additionally, or alternatively, the valve may include a stepper motor or other equivalent technology. The controller unit may also communicate with the motor controller 110 to command the motor controller to open or close the compressor.

[0034] The opening ratio of the valve can also be controlled, for example in proportion to the command given by the controller unit. For example, when the flow meter 114 shows that the vapor at the inlet of the evaporator is above a threshold amount, the controller can command one or more valves to "open X%". The valve responds by opening to X%, thereby increasing the fluid circulation to the compressor (assuming that the compressor is not bypassed). When the amount of vapor decreases, the opening of the valve can be similarly commanded to be smaller, for example "open Y%". In the third mode, one or more valves can control the fluid circulation to the compressor in this way. The command can be proportional to the amount of fluid in the form of vapor sensed at the inlet of the evaporator.

[0035] In some embodiments, the one or more valves include a three-way valve 112 that is operated to connect the evaporator fluid to only the first condenser in a first mode. In the first mode, the three-way valve can be operated to restrict fluid circulation to the first loop (passive loop). In this first loop, the fluid circulates from the evaporator to the first condenser and then back to the evaporator.

[0036] In the second mode, the three-way valve is operated to still circulate the fluid to the first circuit, but also allows the fluid to flow through the second circuit (the switching circuit). In this circuit, the fluid circulates from the evaporator to the bypass valve, to the second compressor, to the thermal expansion valve and back to the evaporator. Thus, in this mode, the bypass valve is operated to be open.

[0037] In the third mode, the three-way valve is operated to allow fluid to flow in the first circuit and also to the compressor 108. One or more valves may include a bypass valve 118, which is connected in parallel with the compressor and in series with the second condenser. In the third mode, the bypass valve can be operated to close, which forces the fluid to circulate through the third circuit (limiting circuit). In this circuit, the fluid circulates from the evaporator to the compressor, the second condenser, the thermal expansion valve and back to the evaporator. In all three modes, the fluid flows through the first circuit.

[0038] As about Figure 1 In the manner described, the cooling system has active phase change cooling (limit loop) integrated with passive phase change cooling (passive loop and conversion loop). The circulation in these loops is controlled by pressure to accommodate low and high heat sources under different thermal conditions.

[0039] Figure 2 An embodiment for controlling a cooling system described in the present disclosure (such as Figure 1 , 4 5) of the process 200. This process can be performed by the controller unit of the cooling system. The entire system is controlled to work in three modes. The cooling system is based on the pressure at the evaporator outlet (in Figure 1 The pressure at (shown as P4) in the figure automatically switches between the first mode, the second mode and the third mode.

[0040] In the first mode (passive mode), only the evaporator and the first condenser are active (passive circuit). At operation 202, when the pressure (P4) at the evaporator outlet is lower than the first pressure threshold P th1 , the cooling system switches to the first mode. Based on this condition, the process continues to operation 204, where the cooling system operates in a passive mode. One or more valves (e.g., a three-way valve) of the cooling system are adjusted to circulate the fluid only through the evaporator and the first condenser. There is no pressure difference across the thermal expansion valve. The steam is cooled by the condenser and not by the compressor or the second condenser of the cooling system. As described above, the forces driving the movement of the fluid are gravity and buoyancy. The physical mechanism is a thermosyphon.

[0041] In the conversion mode, the steam is cooled by both the first condenser and the second condenser, but the compressor is bypassed and stopped. The second condenser operates in a passive manner to supplement the first condenser. At operation 206, when the pressure at the evaporator outlet is higher than the first pressure threshold P th1 and is lower than the second pressure threshold P th2When the condition is satisfied, the cooling system switches to the second mode. Based on this condition, the process continues to operation 208, where the cooling system operates in the switching mode. One or more valves are adjusted to circulate fluid in a) the evaporator and the first condenser (passive loop) and b) the evaporator and the second condenser (switching loop). The switching loop also includes a thermal expansion valve, but in the switching mode, the thermal expansion valve does not release pressure.

[0042] In the limit mode, the fluid, which is mainly or completely in the form of vapor, is partially cooled by the condenser and partially cooled by a vapor compression circuit (limit circuit) including an evaporator, a compressor, a second condenser and a thermal expansion valve. At operation 210, when the pressure (P4) at the evaporator outlet is higher than the second pressure threshold P th2 , the cooling system switches to a third mode. Based on this condition, the process continues to operation 212, where the cooling system operates in an extreme mode. For example, one or more valves are adjusted by closing the bypass valve while maintaining fluid connectivity between the evaporator and the compressor to coordinate the fluid circulation between a) the evaporator and the first condenser (passive loop) and c) the evaporator, the compressor and the second condenser (terminal loop). The pressure drops across the thermal expansion valve. This third loop forms a cooler, thereby extracting a large amount of thermal energy from the heat source when needed.

[0043] When in extreme mode, operation 216 may check whether there is too much steam entering the inlet of the evaporator. Figure 1 As discussed, the flow meter can make measurements for determining how much of the fluid is in the form of vapor at the inlet of the evaporator. If the vapor is greater than a threshold amount, such as >10%, the process can proceed to operation 214 to adjust one or more valves (e.g., a three-way valve) to direct more vapor to the compressor. This will further increase the overall heat transfer of the system, extracting more thermal energy from the fluid at the second condenser, resulting in less vapor at the inlet of the evaporator.

[0044] As discussed, pressure is used to control the valve opening state and the opening ratio (e.g., 50%, 75%, etc.) and the on / off state of the compressor. The on / off state of the compressor is limited in the third mode (extreme mode) to ensure that only vapor enters the compressor to protect the compressor from liquid fluid that can damage the compressor, and at the same time minimize the use of the compressor for improving efficiency and shelf life. Therefore, the compressor operates in a healthy manner.

[0045] When the pressure at the evaporator outlet (P4) is lower than P th1 (first mode), this indicates that the heat source below the evaporator generates low heat, so that there are both steam and liquid before the three-way valve, and the steam can be completely condensed in the first condenser. In other words, based on this pressure, the passive circuit is sufficient to transfer heat energy away from the heat source. In some embodiments, Pth1 is 15 psi. In some embodiments, P th2 is 130 psi. However, it should be understood that the threshold value may vary based on the application, such as, for example, the type of fluid used and the phase change temperature of such fluid. These threshold values ​​may be determined through testing and experimentation.

[0046] When P4 is greater than P th1 But less than P th2 When (second mode), this indicates that the heat generation of the heat source is at an intermediate level and the first condenser and the second condenser are needed to condense the steam. Therefore, for higher heat loads, the system can use multiple condensers in the second mode to adjust, but still remain passive.

[0047] When P4 is greater than P th2 (third mode), which indicates that the heating of the heat source is high. This situation includes when the coolant is completely evaporated (100%) at the outlet of the evaporator. The extreme mode becomes active in this case and the compressor provides additional cooling capacity.

[0048] Figure 3 The use of a buffer around the pressure threshold to define the switching (conversion) cutoff is shown to ensure that the compressor operates without excessive start and stop cycles. The buffers DP1 (a first predefined pressure amount) and DP2 (a second predefined pressure amount) may be relative to P th2 When the pressure P4 is greater than P th2 It must continue to P th2 +DP1, so that the controller thinks that P4 is greater than P th2 As described above, when this occurs, the controller may switch the cooling system to the third mode. Similarly, when the pressure is below P th2 It must continue until it is at P th2 When this happens, the controller may switch the cooling system out of the third mode, for example, to the second mode.

[0049] It should be understood that although Figure 1 The one or more valves 106 are shown to include a three-way valve 112 and a bypass valve 118 to coordinate the fluid circulation in the first, second and third modes, but other arrangements of controllable valves may also be implemented, such as Figure 4 For example, Figure 4, the cooling system 400 includes one or more valves 402, which may include three valves. Valve 404 controls fluid connectivity in the passive loop. In all three modes, the passive loop can remain open, and in some embodiments, valve 404 does not exist, but the fluid pipeline is always connected between the evaporator and the condenser. Another valve 408 bypasses the compressor to control the fluid connectivity to the conversion loop. Another valve 406 controls the fluid connectivity in the limit loop. In the second mode, the bypass valve 408 can be opened and the valve 406 is closed. In the third mode, the bypass valve 408 can be closed and the valve 406 can be opened. As discussed, the compressor valve 406 can be adjusted based on how much steam flows back to the evaporator.

[0050] Other arrangements of one or more valves may also be implemented and coordinated to control the cooling system to operate in the modes described in this disclosure. All aspects described with respect to other embodiments of the cooling system, such as with respect to Figure 1-3 and those described in 5-6, except for the specific three-way valve arrangement, also apply to Figure 4 .

[0051] In addition, refer to Figure 5 , the cooling system 500 has a plurality of spare condensers 502, replacing the second condenser. In other words, the second condenser includes a plurality of condensers. As shown in the figure, these condensers can share a single bypass valve. All other aspects described with respect to other embodiments of the cooling system, such as with respect to Figure 1-4 and those described in 6 also apply to Figure 5 Therefore, in the second mode, a plurality of secondary condensers can be implemented in parallel.

[0052] As described above, the cooling system as described in the above embodiments may be thermally connected to a heat source (eg, a GPU, a CPU, or other IT equipment). The IT equipment may be housed in an electronics rack. Figure 6 940, which may be any of the cooling system embodiments described above. Electronics rack 900 may include one or more servers, each having one or more processing units attached to the bottom of any of the cooling systems described above (e.g., cooling system 940). Figure 6According to one embodiment, the electronic rack 900 includes, but is not limited to, a CDU 901, a rack management unit (RMU) 902 (optional), and one or more blade servers 903A-903D (collectively referred to as blade servers 903). The blade servers 903 can be inserted into the array of server slots from the front end 904 or the back end 905 of the electronic rack 900, respectively. Note that although only five blade servers 903A-903E are shown here, more or fewer blade servers can be maintained within the electronic rack 900. It should also be noted that the specific locations of the CDU 901, RMU 902, and blade servers 903 are shown only for illustrative purposes; other arrangements or configurations of the CDU 901, RMU 902, and blade servers 903 can also be implemented. Note that the electronic rack 900 can be open to the environment or partially contained by a rack container, as long as the cooling fans can generate airflow from the front end to the back end.

[0053] In addition, for each of the blade servers 903, a fan module is associated with the blade server. In this embodiment, fan modules 931A-931E, collectively referred to as fan modules 931, are associated with blade servers 903A-903E, respectively. Each of the fan modules 931 includes one or more cooling fans. The fan modules 931 can be mounted on the rear end of the blade server 903 to generate an airflow that flows from the front end 904, travels through the air space of the blade server 903, and is present at the rear end 905 of the electronics rack 900.

[0054] In one embodiment, CDU 901 mainly includes a heat exchanger 911, a liquid pump 912 and a pump controller (not shown) and some other components, such as a liquid reservoir, a power supply, a monitoring sensor, etc. The heat exchanger 911 can be a liquid-liquid heat exchanger. The heat exchanger 911 includes a first loop with an inlet and an outlet, and the first loop has a first pair of liquid connectors coupled to an external liquid supply / return line 931-932 to form a main loop. The connector coupled to the external liquid supply / return line 931-932 can be arranged or installed on the rear end 905 of the electronic rack 900. The liquid supply / return line 931-932 is coupled to a set of room manifolds, and the room manifold is coupled to an external heat removal system or an extreme cooling loop. In addition, the heat exchanger 911 also includes a second loop with two ports, and the second loop has a second pair of liquid connectors coupled to the liquid manifold 925 to form a secondary loop, which can include a supply manifold for supplying cooling liquid to the blade server 903 and a return manifold for returning warmer liquid to the CDU 901. Note that the CDU 901 may be any kind of commercially available CDU or a customized CDU. Therefore, the details of the CDU 901 will not be described herein.

[0055] Each of the blade servers 903 may include one or more IT components (e.g., a central processing unit or CPU, a graphics processing unit (GPU), memory, and / or storage device). Each IT component may perform data processing tasks, wherein the IT component may include software installed in a storage device, loaded into a memory, and executed by one or more processors to perform data processing tasks. At least some of these IT components may be attached to the bottom of any one of the cooling systems described above. The blade server 903 may include a host server (referred to as a host node) coupled to one or more computing servers (also referred to as computing nodes, such as CPU servers and GPU servers). The host server (with one or more CPUs) typically interfaces with a client over a network (e.g., the Internet) to receive requests for specific services, such as storage services (e.g., cloud-based storage services such as backup and / or recovery), executing applications to perform certain operations (e.g., image processing, deep data learning algorithms or modeling, etc. as part of a software as a service or SaaS platform). In response to the request, the host server assigns the task to one or more performance computing nodes or computing servers (with one or more GPUs) managed by the host server. The performance computing server performs the actual task, which may generate heat during operation.

[0056] The electronics rack 900 also includes an optional RMU 902 that is configured to provide and manage power supplied to the servers 903, the fan modules 931, and the CDU 901. The RMU 902 can be coupled to a power supply unit (not shown) to manage the power consumption of the power supply unit. The power supply unit can include necessary circuits (e.g., alternating current (AC) to direct current (DC) or DC to DC power converters, backup batteries, transformers or regulators, etc.) to provide power to the remaining components of the electronics rack 900.

[0057] In one embodiment, the RMU 902 includes an optimization module 921 and a rack management controller (RMC) 922. The RMC 922 may include a monitor for monitoring the operating status of various components within the electronic rack 900, such as the computing node 903, the CDU 901, and the fan module 931. Specifically, the monitor receives operating data from various sensors representing the operating environment of the electronic rack 900. For example, the monitor may receive operating data representing the temperature of the processor, cooling liquid, and airflow, which may be captured and collected via various temperature sensors. The monitor may also receive data representing the fan power and pump power generated by the fan module 931 and the liquid pump 912, which may be proportional to their respective speeds. These operating data are referred to as real-time operating data. Note that the monitor may be implemented as a separate module within the RMU 902.

[0058] Based on the operating data, the optimization module 921 performs optimization using a predetermined optimization function or optimization model to derive a set of optimal fan speeds for the fan module 931 and an optimal pump speed for the liquid pump 912, so that the total power consumption of the liquid pump 912 and the fan module 931 is minimized, while the operating data associated with the liquid pump 912 and the cooling fan of the fan module 931 and the cooling fan are within their respective design specifications. Once the optimal pump speed and the optimal fan speed are determined, the RMC 922 configures the liquid pump 912 and the cooling fan of the fan module 931 based on the optimal pump speed and the fan speed.

[0059] As an example, based on the optimal pump speed, the RMC 922 communicates with the pump controller of the CDU 901 to control the speed of the liquid pump 912, which in turn controls the liquid flow rate of the cooling liquid supplied to the liquid manifold 925 to be distributed to at least some of the blade servers 903. Thus, the operating conditions and the corresponding cooling device performance are adjusted. Similarly, based on the optimal fan speed, the RMC 922 communicates with each of the fan modules 931 to control the speed of each cooling fan of the fan module 931, which in turn controls the airflow rate of the fan module 931. Note that each of the fan modules 931 can be individually controlled with its specific optimal fan speed, and different fan modules and / or different cooling fans in the same fan module can have different optimal fan speeds.

[0060] Note that some or all of the IT components of server 903 may be attached to any of the above cooling systems, such as at the evaporator of the cooling system. One server may utilize air cooling while another server may utilize liquid cooling. Alternatively, one IT component of a server may utilize air cooling while another IT component of the same server may utilize liquid cooling.

[0061] It should be understood that various features shown with respect to one figure may also exist in other embodiments of different features.

[0062] In the foregoing description, embodiments of the present invention have been described with reference to specific exemplary embodiments of the present invention. However, it will be apparent that various modifications may be made thereto without departing from the broader spirit and scope of the present invention as set forth in the appended claims. Accordingly, the description and drawings are to be regarded as illustrative rather than restrictive.

Claims

1. A cooling system, comprising: an evaporator, the evaporator being connected to the first condenser, the second condenser, the compressor and a thermal expansion valve through a fluid pipeline, the thermal expansion valve being connected to the first condenser and the second condenser respectively; as well as One or more valves are arranged in the fluid pipeline, and the one or more valves are operated to In a first mode, a fluid is circulated between the evaporator and the first condenser, the evaporator and the first condenser forming a thermosiphon loop that passively circulates between the evaporator and the first condenser without the use of a motor or a pump; In a second mode, a fluid is circulated between a) the evaporator and the first condenser and b) the evaporator, the second condenser and the thermal expansion valve, and In a third mode, a fluid is circulated between a) the evaporator and the first condenser and c) the evaporator, the compressor, the second condenser, and the thermal expansion valve. 2 . The cooling system of claim 1 , wherein the cooling system automatically switches between the first mode, the second mode, and the third mode based on a pressure at an outlet of the evaporator. 3 . The cooling system of claim 2 , wherein the cooling system switches into the first mode when the pressure at the outlet of the evaporator is below a first pressure threshold.

4. The cooling system of claim 2, wherein the cooling system switches into the second mode when the pressure at the outlet of the evaporator is above a first pressure threshold and below a second pressure threshold. 5 . The cooling system of claim 4 , wherein the cooling system switches into the third mode when the pressure at the outlet of the evaporator is higher than the second pressure threshold.

6. The cooling system of claim 4, wherein when the pressure at the outlet of the evaporator is greater than the second pressure threshold by a first predefined amount, the cooling system switches to the third mode, and when the pressure at the outlet of the evaporator is less than the second pressure threshold by a second predefined amount, the cooling system switches out of the third mode.

7. The cooling system of claim 1, wherein the compressor is turned on in the third mode and is turned off in the first mode and the second mode.

8. The cooling system of claim 1, wherein: In the third mode, pressure is released through the thermal expansion valve, thereby creating a pressure drop across the thermal expansion valve, and in the second mode, the pressure across the thermal expansion valve is maintained consistent.

9. The cooling system of claim 1, wherein: In the third mode, based on measurements indicative of an amount of the fluid in vapor form at an inlet to the evaporator, the one or more valves are operated to increase the circulation of the fluid from the evaporator to the compressor and the second condenser.

10. The cooling system of claim 1, wherein the one or more valves include a three-way valve that is operated to fluidly connect the evaporator to only the first condenser in the first mode.

11. The cooling system of claim 10, wherein the one or more valves include a bypass valve connected in parallel with the compressor and in series with the second condenser, the second condenser being operated to In the second mode, the compressor is opened and bypassed, causing fluid to circulate from the evaporator to the second condenser, and and being closed in the third mode, resulting in fluid being circulated from the compressor to the second condenser in the third mode.

12. The cooling system of claim 1, wherein the second condenser is composed of a plurality of sub-condensers.

13. The cooling system of claim 1, wherein the compressor is an adjustable compressor, and adjustment of the compressor provides a varying cooling capacity.

14. An electronic rack, comprising: IT equipment; and A cooling system thermally coupled to the IT equipment, the cooling system being the cooling system according to any one of claims 1 to 13.

15. A non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the cooling system of any one of claims 1-13.

16. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the cooling system according to any one of claims 1 to 13 are implemented.

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