System and method for phase change cooling of electronic racks

Abstract

According to one embodiment, the cooling system comprises: a main condenser; a main supply line and a main return line coupling the main condenser to a cooling station to create a main heat transfer loop, the cooling station being arranged for cooling of electronic equipment, in which main heat transfer loop the condenser supplies liquid coolant to the cooling station and receives vapor generated by the cooling station; a secondary condenser; a secondary supply line coupling the secondary condenser to the main supply line; a secondary return line coupling the secondary condenser to the main return line; and a main valve coupled to the secondary return line, wherein in response to a vapor pressure exceeding a pressure threshold, the main valve at least partially opens to create a secondary heat transfer loop in which the secondary condenser condenses the vapor back into liquid coolant supplied to the main supply line.

Description

Technical Field

[0001] Embodiments of this disclosure generally relate to cooling systems for phase change cooling of electronic racks. Background Technology

[0002] Thermal management of data centers, including several active electronic racks, is crucial for ensuring the proper performance of servers and other information technology (IT) equipment operating within the racks (e.g., performing IT data processing services). However, without proper thermal management, the thermal environment within the racks (e.g., temperature) can exceed thermal operating thresholds, potentially leading to adverse consequences (e.g., server failures). One approach to managing the thermal environment is to use cooling air to cool IT equipment. Cooling air is recirculated using cooling units that extract the heat captured by the air. A common type of cooling unit is the Computer Room Air Conditioning (CRAC) unit, which is a device that draws in hot exhaust gases and supplies cooling air to the data center to maintain its thermal environment. CRACs are widely used air-cooled data centers, and many other types of solutions exist for air-cooled data centers. Furthermore, most existing data centers are air-cooled.

[0003] Recently, data centers have deployed higher power-density electronic racks, where higher-density chips are more tightly packed together to provide greater processing power. This is especially true for the development of artificial intelligence (AI) and cloud-based services that require high-performance and high-power-density processors such as control processing units (CPUs) and graphics processing units (GPUs). Maintaining the appropriate thermal environment for these high-density racks using existing cooling systems, such as data center air cooling systems, can be problematic. For example, while an air system unit may be able to maintain the thermal environment with more conventional (or lower-density) racks, it may not be effective at cooling high-power-density racks, which may generate heat loads at a higher rate due to the higher density of electronics. In some cases, liquid cooling has become a more efficient and feasible cooling solution for high-power-density or high-heat-flux situations. Summary of the Invention

[0004] Some aspects of this application provide a cooling system for an electronic rack, which may include: a main condenser; a main supply line and a main return line connecting the main condenser to a cooling platform to create a main heat transfer loop, the cooling platform being arranged to be mounted on an information technology component of an information technology device disposed within the electronic rack, wherein, in the main heat transfer loop, the main condenser 1) supplies liquid coolant to the cooling platform via the main supply line, and 2) receives steam generated by the cooling platform via the main return line when heat generated by the information technology component is transferred to the liquid coolant through the cooling platform; a secondary condenser; a secondary supply line connecting the secondary condenser to the main supply line; a secondary return line connecting the secondary condenser to the main return line; and a main valve connected to the secondary return line. In some embodiments, the main valve may be configured to at least partially open in response to a steam pressure exceeding a pressure threshold. In some implementations, a secondary heat transfer loop can be created in response to at least partial opening of the main valve, in which a secondary condenser can receive at least a portion of the steam via a secondary return line and condense at least a portion of the steam back into the liquid coolant supplied to the main supply line via a secondary supply line.

[0005] Other aspects of this application provide an electronic rack that may include: a plurality of information technology devices arranged in a stacked manner for providing data processing services, each of the information technology devices including one or more processors; a main condenser; a main supply line and a main return line connecting the main condenser to a cooling platform to create a main heat transfer loop, the cooling platform being arranged to be mounted on the processors of the information technology devices among the plurality of information technology devices, in the main heat transfer loop, the main condenser 1) supplies liquid coolant to the cooling platform via the main supply line, and 2) receives steam generated by the cooling platform via the main return line when heat generated by the information technology components is transferred to the liquid coolant through the cooling platform; a secondary condenser; a secondary supply line connecting the secondary condenser to the main supply line; a secondary return line connecting the secondary condenser to the main return line; and a main valve connected to the secondary return line. In some embodiments, the main valve may be configured to open at least partially in response to the steam pressure exceeding a pressure threshold. In some implementations, a secondary heat transfer loop can be created in response to at least partial opening of the main valve, in which a secondary condenser can receive at least a portion of the steam via a secondary return line and condense at least a portion of the steam back into the liquid coolant supplied to the main supply line via a secondary supply line.

[0006] Other aspects of this application provide a method for liquid cooling of information technology components of information technology equipment mounted in an electronic rack, the method comprising: determining a vapor pressure in a main heat transfer loop, in which a cooling platform mounted on the information technology component is connected to a main condenser via 1) a main supply line and 2) a main return line, wherein the main supply line supplies liquid coolant to the cooling platform, and the main return line returns vapor generated by the cooling platform to the main condenser as heat generated by the information technology component is transferred to the liquid coolant through the cooling platform; in response to determining the main... When the steam pressure in the heat transfer loop exceeds a pressure threshold, the closed main valve opens, connecting the main return line to the auxiliary condenser. The auxiliary condenser is connected to the main supply line via an auxiliary supply line. When the closed main valve is opened, a secondary heat transfer loop is created, in which at least a portion of the steam is condensed back into the liquid coolant supplied to the main supply line via the auxiliary supply line through the auxiliary condenser. In response to determining that the steam pressure in the main heat transfer loop does not exceed the pressure threshold, the closed main valve remains closed, allowing steam to be condensed back into the liquid coolant only through the main condenser. Attached Figure Description

[0007] Embodiments are illustrated in the accompanying drawings by way of example rather than limitation, and the same reference numerals denote the same elements in the drawings. It should be noted that the terms "embodiment" or "one embodiment" in this disclosure do not necessarily refer to the same embodiment, but rather to at least one embodiment. Furthermore, for the sake of brevity and to reduce the total number of drawings, a given set of drawings may be used to illustrate features of more than one embodiment, and not all elements in the drawings are necessary for a given embodiment.

[0008] Figure 1 This is a block diagram illustrating an example of a cooling system according to one embodiment, which is a cooling component for an information technology (IT) device having a main condenser.

[0009] Figure 2 This is a block diagram illustrating an example of a cooling system according to one embodiment, which is a cooling component of an IT device having a main condenser and a secondary condenser.

[0010] Figure 3 This is a block diagram illustrating another example of a cooling system with a buffer according to one embodiment.

[0011] Figure 4 This is a flowchart of the process for a liquid cooling component of an IT device according to one embodiment.

[0012] Figure 5 This is a flowchart of another process for the liquid cooling component of an IT device according to one embodiment. Detailed Implementation

[0013] Several embodiments of this disclosure will now be described with reference to the accompanying drawings. Unless the shape, relative position, and other embodiments of the components described in a given embodiment are explicitly defined, the scope of this disclosure is not limited to the components shown, which are for illustrative purposes only. Furthermore, although numerous details are set forth, it should be understood that some embodiments can be practiced without these details. In other instances, well-known circuits, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification. Moreover, unless the meaning is clearly to the contrary, all scopes described herein are to be considered to include the endpoints of each scope.

[0014] The use of "one embodiment" or "implementation" in the specification means that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this disclosure. The phrase "in one embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment.

[0015] Various embodiments of this disclosure describe phase change cooling systems for electronic racks (e.g., high power density) that can be installed in data center rooms. The cooling system solution uses two phase change technology to design two heat transfer loops: a first (or primary) heat transfer loop for constantly transferring heat generated by information technology (IT) equipment; and a second (or secondary) heat transfer loop for transferring additional heat generated by the IT equipment during high-power workloads (e.g., when the power density of the electronic rack exceeds a power threshold). The primary heat transfer loop may include a primary condenser coupled to one or more cooling platforms on IT components (e.g., processors) of the IT equipment mounted in the rack. Liquid coolant can flow from the primary condenser to the cooling platforms, where it vaporizes as heat generated by the IT components is transferred through the cooling platforms. This vapor can then be condensed back into the liquid coolant via the primary condenser, and the liquid coolant is subsequently replenished to the cooling platforms.

[0016] The secondary heat transfer loop may include a secondary condenser connected to the cooling platform via a main valve. When the electronics rack is under “nominal” or normal operating conditions (e.g., when the power density is below a power threshold), this main valve remains closed, and the rack is cooled through the main heat transfer loop. However, when the vapor pressure within the system increases above a pressure threshold, the main valve may open, allowing vapor to condense through the secondary condenser. This can occur under high-power operating load conditions for the electronics rack, where additional heat generated by IT components causes the cooling platform to produce more vapor, increasing the vapor pressure within the closed system. When the vapor pressure decreases (e.g., the rack returns to nominal operating conditions with lower rack power consumption), the pressure valve may close, and the system can then be cooled through the main heat transfer loop without using the secondary loop. Therefore, the main condenser in the main heat transfer loop can provide a fixed and constant cooling capacity (e.g., unrestricted by any system limitations) regardless of the electronics rack's power consumption. The cooling system described herein offers advantages. For example, the system is designed as a self-regulating system to achieve better performance under varying operating conditions and allows for significant variations in the cooling capacity of the heat transfer loop and the heat load generated by the IT equipment. Furthermore, the system enables cost-effective control, with the auxiliary condenser used only when needed. Additionally, the cooling system reduces complexity by providing sufficient and constant cooling to the main heat transfer loop when the rack is operating under normal conditions.

[0017] Furthermore, the cooling system can reconfigure (or adjust) the opening pressure of the main valve based on changes in the cooling requirements of the electronic rack. For example, the pressure threshold for the main valve to open can be based on the configuration of the electronic rack (e.g., the number and type of IT equipment installed in the rack) and the cooling capacity of the main condenser. If either of these changes (e.g., the rack configuration is altered by replacing, adding, and / or removing IT equipment installed in the rack), the pressure threshold can also change. For example, as higher power density equipment is added to the rack, the maximum power density of the entire configuration may increase. This may require a decrease in the pressure threshold compared to a rack with lower power density equipment, as the heat generated by the added high power density equipment and the heat that needs to be transferred from the added high power density equipment increases accordingly. Therefore, the cooling system can control the increase in the cooling capacity of the auxiliary condenser relative to the cooling capacity of the main condenser (which remains constant) to cool the electronic rack by adjusting the opening pressure of the main valve according to the current configuration of the electronic rack.

[0018] According to one embodiment, a cooling system for an electronic rack includes: a main condenser; a main supply line and a main return line connecting the main condenser to a cooling platform arranged on IT components of information technology (IT) equipment disposed within the electronic rack to create a main heat transfer loop in which the main condenser 1) supplies liquid coolant to the cooling platform via the main supply line, and 2) receives steam generated by the cooling platform via the main return line when heat generated by the IT components is transferred to the liquid coolant via the cooling platform; a secondary condenser; a secondary supply line connecting the secondary condenser to the main supply line; a secondary return line connecting the secondary condenser to the main return line; and a main valve connected to the secondary return line. The main valve is configured to at least partially open in response to a steam pressure exceeding a pressure threshold of the main valve, and in response to the at least partial opening of the main valve, a secondary heat transfer loop is created in which the secondary condenser receives at least a portion of the steam via the secondary return line and condenses at least a portion of the steam back into the liquid coolant supplied to the main supply line via the secondary supply line.

[0019] In one embodiment, the cooling system further includes: 1) a fan arranged to move ambient air using the cooling coils of the secondary condenser; or 2) a rack supply line and a rack return line connecting the secondary condenser to a cooling source and a secondary valve, the secondary valve being connected to the rack supply line or the rack return line depending on the cooling method of the secondary cooling condenser (air-cooled condenser or liquid-cooled condenser). In some embodiments, the cooling system further includes a pressure sensor connected to the secondary return line and communicatively connected to the fan or the secondary valve, wherein the pressure sensor is configured to sense the vapor pressure within the secondary return line and adjust the fan speed of 1) the fan or the opening ratio of 2) the secondary valve based on the sensed pressure.

[0020] In one embodiment, the cooling system further includes a controller communicatively connected to the main valve, wherein the controller is configured to determine a pressure threshold based on at least one of a maximum power threshold of the electronic rack and the cooling capacity of the main condenser, and to set the opening pressure of the main valve according to the pressure threshold.

[0021] In some embodiments, the cooling system further includes: a supply distribution manifold connecting the main supply line to the cooling platform; and a return distribution manifold connecting the main return line to the cooling platform. In another embodiment, the cooling system further includes a liquid coolant buffer connected between the main supply line and the supply distribution manifold. In one embodiment, the auxiliary condenser is positioned above the main condenser, which is positioned above the IT equipment, wherein steam and liquid coolant circulate through each of the main and auxiliary heat transfer loops without any steam pump or any liquid pump. In another embodiment, the main condenser is a first-type two-phase heat exchanger, and the auxiliary condenser is a second-type two-phase heat exchanger.

[0022] According to one embodiment, the electronic rack includes a plurality of information technology (IT) devices stacked together for providing data processing services, and includes at least some components of the cooling system described herein, wherein each IT device includes one or more processors.

[0023] According to another embodiment, a method for liquid cooling of information technology (IT) components of IT equipment installed in an electronic rack includes: determining a vapor pressure in a main heat transfer loop, in which a cooling platform mounted on the IT components is connected to a main condenser via a main supply line and a main return line, wherein 1) the main supply line supplies liquid coolant to the cooling platform and 2) when heat generated by the IT components is transferred to the liquid coolant through the cooling platform, the main return line returns vapor generated by the cooling platform to the main condenser; in response to determining the main heat transfer loop... If the steam pressure in the main heat transfer circuit exceeds a pressure threshold, the closed main valve opens, connecting the main return line to the auxiliary condenser, which in turn connects to the main supply line via a secondary supply line. When the main valve opens, a secondary heat transfer loop is created, in which at least a portion of the steam is condensed back into the liquid coolant supplied to the main supply line via the secondary supply line by the auxiliary condenser. In response to determining that the steam pressure in the main heat transfer loop does not exceed the pressure threshold, the closed main valve remains closed, allowing steam to be condensed back into the liquid coolant only through the main condenser.

[0024] In one embodiment, a main valve is connected to a secondary return line that connects the main return line to the secondary condenser. The method further includes: sensing vapor pressure within the secondary return line; and adjusting either 1) the fan speed of a fan or 2) the opening ratio of a secondary valve, the fan being arranged to move ambient air using the cooling coils of the secondary condenser, the secondary valve connecting the secondary condenser to a liquid cooling source based on the sensed pressure. In some embodiments, the method further includes: determining a pressure threshold based on at least one of a maximum power threshold of the electronic rack and the cooling capacity of the main condenser; and setting the opening pressure of the main valve according to the pressure threshold. In one embodiment, the method further includes: determining a new maximum power threshold of the electronic rack based on a change in the configuration of the electronic rack; determining a new pressure threshold based at least on the new maximum power threshold; and setting the opening pressure of the main valve according to the new pressure threshold.

[0025] In one implementation, as used herein, “coupling” one component (or element) to another component can mean “fluidly” connecting the two components such that a fluid (or vapor), such as a cooling liquid or liquid coolant, can flow between the two components. For example, connecting a first pipe to a second pipe can mean connecting the two pipes together to allow fluid to flow from the first pipe to the second pipe.

[0026] Figure 1 This is a block diagram illustrating an example of a cooling system 1 according to one embodiment, which is a cooling component for information technology (IT) equipment having a main condenser. Specifically, Figure 1 The illustrated (e.g., phase change liquid) cooling system 1 includes a main condenser 3, a secondary condenser 4, a controller 6, a main valve 13, a pressure sensor 14, a fan 16, a secondary valve 15, a main supply line 9, a secondary supply line 11, a supply distribution manifold 7, a main return line 10, a secondary return line 12, and a return distribution manifold 8. In one embodiment, the system may include one or more components (or elements) as shown herein. For example, the system may include one or more pressure sensors, one or more fans, and / or one or more (additional) valves. As another example, the system may include a fan 16 or a secondary valve 15 as described herein.

[0027] Figure 1 An electronic rack 2 comprising one or more stacked IT devices 5a to 5n is also shown. In one embodiment, the electronic rack may include one or more (server) slots, each designed to include one or more IT devices. Each IT device may include one or more IT components (e.g., one or more processors, central processing units or CPUs, graphics processing units (GPUs), memory and / or storage devices). The IT components may perform data processing tasks, wherein the IT components may include software installed in storage devices, loaded into memory, and executed by one or more processors to perform data processing tasks. In one embodiment, the IT device 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 (having one or more CPUs) typically interfaces with clients via 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), to execute applications to perform specific operations (e.g., image processing, deep data learning algorithms or models, etc., as part of a Software as a Service or SaaS platform). In response to this request, the host server assigns the task to one or more performance computing nodes or compute servers (with one or more GPUs or different types of accelerators) managed by the host server. IT components (e.g., processors) perform computing tasks, which generate heat. As described herein, this heat needs to be dissipated from the components to ensure they do not overheat, which could lead to malfunction.

[0028] Each IT device 5a to 5n includes at least one of cooling platforms 21a to 21n, which are arranged to be mounted on an IT component (not shown) of the respective IT device. Each cooling platform is designed to provide phase-change liquid cooling to one or more IT components on which the cooling platform is mounted. For example, when heat generated by the IT component on which the cooling platform is mounted is transferred to a liquid coolant through the cooling platform, the cooling platform receives the liquid coolant and generates vapor. Further details regarding the cooling platforms are described herein.

[0029] In one embodiment, the liquid coolant can be any type (or one or more types) of phase change liquid (or fluid). In some embodiments, the coolant may have a boiling point capable of causing a phase change (e.g., a phase change to gas or vapor) based on the IT equipment on which a cooling platform is mounted (e.g., an IT component mounted on an IT equipment). Specifically, the coolant may have a boiling point below (or equal to) a threshold value of the operating temperature of the IT component (e.g., the temperature of the IT component, such as the case temperature of a chip, that results in heat generation by the IT component when a predetermined power density is drawn).

[0030] As shown herein, at least some components of the cooling system 1 are included (or disposed in part) within the electronic rack 2. For example, IT devices 5a to 5n, the controller 6, the supply distribution manifold 7 and the return distribution manifold 8, and the main condenser 3 and the auxiliary condenser 4 are included within the electronic rack. In another embodiment, Figure 1 Some (or all) components of the cooling system 1 shown may be included within the rack. Therefore, in this example, the entire cooling system may be included (or housed) within rack 2. In another embodiment, one or more components may be located outside the rack. For example, two (or at least one) condensers may be located on top of the rack (and / or externally). As another example, fan 16 and / or sub-valve 15 may be located externally to the rack and coupled to it. For example, fan 16 may be coupled to the rack (e.g., the rear end of the rack) to push (or draw) ambient air (e.g., data center cooling air). As another example, controller 6 may be located externally to the rack (e.g., included within a different rack).

[0031] The main condenser 3 can be any type of two-phase heat exchanger (e.g., liquid-to-liquid heat exchanger, liquid-to-air heat exchanger, etc.) designed to condense vapor into a cooling (condensed) liquid (or condensate). Similarly, the secondary condenser 4 can be any type of two-phase heat exchanger. In one embodiment, the cooling system 1 may include a fan 16 or a secondary valve 15 depending on the type of heat exchanger included in the secondary condenser. For example, if the secondary condenser is a liquid-to-air heat exchanger, the cooling system may include one or more fans 16 arranged to move cooling air using at least one cooling coil of the secondary condenser. The cooling air is then used to cool the vapor flowing into the cooling coil. Furthermore, if the secondary condenser is a liquid-to-liquid heat exchanger, the cooling system includes a secondary valve 15 that can be coupled to either 1) a rack supply line 17 or 2) a rack return line 18, the rack supply line 17 supplying liquid coolant from a cooling source (e.g., a cooling liquid system in a data center) to the secondary condenser 4, and the rack return line 18 returning the heated liquid coolant to the cooling source. The cooling liquid is then used to cool the steam. In one embodiment, the two condensers can be different types of heat exchangers (e.g., the main condenser is a liquid-to-liquid heat exchanger, while the auxiliary condenser is a liquid-to-air heat exchanger). In some embodiments, the cooling system 1 may include additional fans, valves, and supply / return lines for cooling the main condenser. On the other hand, as described herein, the cooling system may include additional condensers coupled to a cooling platform.

[0032] As shown in the figure, the main supply line 9 and the main return line 10 connect the main condenser 3 to one or more cooling platforms 21a to 21n to create a main heat transfer loop (e.g., one loop for each cooling platform). Specifically, the main supply line connects the main condenser to the supply distribution manifold 7, and the main return line connects the main condenser to the return distribution manifold 8. Thus, the supply manifold and the return manifold are configured to connect one or more cooling platforms (e.g., removably) to the main supply line and the main return line, respectively, such that the heat transfer loop of the cooling platform can be added to or removed from the cooling system 1. In particular, as shown with reference to cooling platform 21a, each cooling platform is connected to the supply distribution manifold via IT supply line 19, and similarly, each cooling platform is connected to the return distribution manifold via IT return line 20. As described herein, the main heat transfer loop draws heat from IT equipment (e.g., IT components on which cooling platforms are mounted). For example, the main condenser supplies liquid coolant (e.g., condensate) to the supply distribution manifold via the main supply line 9, and the supply distribution manifold then distributes and supplies coolant to each cooling station 21a to 21n via the IT supply line 19. The cooling station heats the liquid coolant into vapor, which flows into the return distribution manifold via the IT return line 20. The vapor then flows from the return manifold into the main return line 10, from which the main condenser 3 receives the vapor to be condensed back into liquid coolant.

[0033] The auxiliary condenser 4 is connected in parallel with the main condenser 3. As shown, the auxiliary supply line 11 connects the auxiliary condenser 4 to the main supply line 9, and the auxiliary return line 12 connects the auxiliary condenser to the main return line 10 to create a secondary heat transfer loop (e.g., under specific operating conditions of the electronics rack, such as when the rack is handling high-power workloads, as described herein). Further details of the secondary heat transfer loop are described herein. In one embodiment, the auxiliary condenser may be connected in other ways. For example, the auxiliary supply line may be connected to the supply distribution manifold 7 instead of the main supply line. The main valve 13 and pressure sensor 14 are connected to the auxiliary return line. In one embodiment, the auxiliary return line may include two parts: a first part connecting the auxiliary return line between the main return line and the main valve, and a second part connecting the auxiliary condenser and the main valve and connected to the pressure sensor. In one embodiment, the pressure sensor may be connected to the first part of the auxiliary return line.

[0034] In one embodiment, the main valve 13 is configured to control the steam flow from the main return line (and via the secondary return line) into the secondary condenser 4. In one embodiment, the main valve may be a pressure valve configured to at least partially open in response to the steam pressure in the main heat transfer loop (e.g., the steam pressure in the main return line 10) exceeding a pressure threshold. For example, the main valve may have an opening pressure (e.g., the pressure at which the valve at least partially opens) defined (or set) according to the pressure threshold. Thus, when the main valve is opened, a secondary heat transfer loop is created, allowing steam to flow into the secondary condenser in response to the at least partial opening of the main valve 13. Specifically, when the valve is open, steam (or at least a portion of the steam) generated by the cooling platform flows from the main return line through the secondary return line 12 and is received by the secondary condenser 4, which condenses the steam back into liquid coolant, which is then supplied to the main supply line 9 via the secondary supply line 11. In one embodiment, the opening of the main valve 13 allows additional steam (e.g., additional steam that the main condenser 3 cannot effectively condense) to be condensed by the secondary condenser. In some implementations, the main valve may be a proportional valve, which (e.g., automatically) adjusts its opening ratio to provide a proportional change in output pressure (e.g., the pressure at the outlet of the valve connected to the secondary return line) that is similar to (or the same as) the change in input pressure (e.g., the pressure at the inlet of the valve connected to the main return line 10).

[0035] However, as Figure 1 As shown, cooling system 1 uses a primary heat transfer loop, rather than a secondary heat transfer loop, for phase change cooling of the electronics rack. For example, supply lines 9 and 19 and supply distribution manifold 7 supply liquid coolant (e.g., condensate) to cooling platforms 21a to 21n (as shown by the solid black lines), while return lines 10 and 20 and return distribution manifold 8 are used to return vapor (e.g., evaporated liquid coolant) from the cooling platforms to the main condenser 3 (as shown by the dashed black lines). The main valve 13 is closed, and therefore vapor does not flow through the secondary return line 12, and condensate does not flow from the secondary condenser 4 through the secondary supply line 11 to the main supply line (as shown by the dotted black lines indicating the secondary return and supply lines).

[0036] Controller 6 may be a dedicated processor, such as an application-specific integrated circuit (ASIC), a general-purpose microprocessor, a field-programmable gate array (FPGA), a digital signal controller, or a set of hardware logic structures (e.g., filters, arithmetic logic units, and dedicated state machines). In one embodiment, the controller may be a circuit having analog elements (e.g., resistors, capacitors, inductors, etc.) and / or digital elements (e.g., logic-based elements such as transistors, etc.). The controller may also include memory. As shown, in one embodiment, the controller may be part of (or integrated into) the electronic rack 2. In another embodiment, the controller may be part of (or one of) IT devices mounted within the electronic rack. The controller is configured to perform one or more phase-change operations to cool the IT devices mounted within the electronic rack. More details regarding these operations are described herein.

[0037] As described herein, the cooling system creates a secondary heat transfer loop in response to the steam pressure of the steam (flowing) within the primary heat transfer loop exceeding a pressure threshold. In one embodiment, the pressure threshold may be the steam pressure corresponding to the electronic rack operating at a high power load (or above). For example, when the steam pressure is below the pressure threshold, the electronic rack 2 (e.g., the IT equipment 5a to 5n of the electronic rack 2) may operate at or below nominal operating conditions (e.g., drawing less power than the (maximum) power density (or threshold)), wherein the IT components of the rack generate a controllable amount of heat that can be dissipated by the primary condenser. Specifically, when the equipment is not operating at a high power load, the (primary) cooling capacity of the primary condenser is greater than (or equal to) the heat generated by the IT equipment. Therefore, when the rack operates under normal power load conditions without drawing power exceeding the power threshold, the primary cooling capacity can efficiently and effectively condense the steam generated by the cooling platforms 21a to 21n. However, if the IT equipment handles high-power workloads (e.g., when the IT equipment has a power density above a power threshold), the IT components generate additional heat, resulting in additional steam being produced through the cooling platform. As the steam volume within the electronics rack (e.g., within the main return line 10) increases, the steam pressure also increases. Therefore, the cooling system 1 is configured to activate the secondary heat transfer loop as needed (e.g., during high-power-density workloads of the IT equipment). In one embodiment, the cooling system 1 typically uses the main heat transfer loop to liquid cool the equipment within the electronics rack.

[0038] In one embodiment, controller 6 is configured to determine the pressure threshold (for when main valve 13 is open) based on the configuration of electronic rack 2. The configuration of the electronic rack may include the number and / or type of IT equipment (and IT components of the equipment) installed within the rack. Depending on the configuration of the electronic rack, the controller may determine the maximum power threshold (or workload) of the electronic rack. For example, each IT equipment may have a power requirement and / or power threshold for equipment operation. The controller may synthesize information from all equipment installed within the electronic rack to determine the maximum power threshold of the rack. In one embodiment, the controller may determine power information about the equipment in various ways. For example, once the equipment is installed in the rack, the controller may retrieve the power requirement from the equipment (e.g., the controller may communicatively connect to each IT equipment). In another embodiment, the controller may receive power information from a user (e.g., from a user terminal) as the electronic rack is filled. In addition to the rack configuration (or alternatively), the pressure threshold may be based on the cooling capacity of the main condenser. In one embodiment, the cooling capacity may be determined based on the number of condensers within the rack. In one embodiment, the controller determines the pressure threshold based on the heat generated by the electronic rack when operating at the maximum power threshold. For example, the controller can be configured to determine the total heat generated by the electronics rack based on a maximum power threshold and compare the threshold to the main cooling capacity of the main condenser. For instance, the controller can determine whether the main cooling capacity of the main condenser is greater than the total heat the electronics rack can generate during high-power workloads. If the maximum power threshold is greater than the main cooling capacity, the controller can limit a pressure threshold based on the main cooling capacity, which may correspond to a power density of the rack below the maximum power threshold. In another embodiment, the controller can use other methods to determine the pressure threshold. In some embodiments, the controller may take rack operating configuration into account when determining (limiting) and setting the pressure threshold.

[0039] For example, the controller can input the maximum power and / or the main condenser cooling (operating) capacity into a predetermined steam pressure model for the output steam pressure value, at which (or above) the secondary heat transfer loop (together with the main heat transfer loop) is used to cool the rack. In other words, this can be understood as using the secondary heat transfer loop to cool the electronic rack for a heat load exceeding the cooling capacity of the main condenser. As another example, the controller can use the maximum power workload to perform a table lookup on a data structure that correlates power values ​​with steam pressure values.

[0040] In another embodiment, the controller may determine a pressure threshold based on a predetermined portion (or fraction) of the maximum power workload. For example, when determining the maximum power workload, the controller may reduce that value by a percentage (e.g., 50%), resulting in a halved maximum power workload. In one embodiment, this reduced workload may at least represent the average workload of the electronic rack. The controller may determine a pressure threshold such that once the equipment mounted in the rack begins to draw on the reduced workload (or more), the cooling system activates a secondary heat transfer loop.

[0041] In one embodiment, controller 6 is communicatively coupled to main valve 13 (e.g., via control line 22). In some embodiments, the control line can be a wired connection via any communication protocol. In some embodiments, controller 6 is configured to set the opening pressure of the main valve based on a pressure threshold by transmitting control signals (e.g., electrical signals) to main valve 13 via control line 22. For example, in one embodiment, the controller can dynamically adjust the opening pressure of the main valve based on configuration changes in the electronics rack (e.g., replacement, addition, and / or removal of IT equipment with different power requirements). Further details regarding the dynamic adjustment of the opening pressure of the main valve are described herein.

[0042] Figure 2 This is a block diagram illustrating an example of a cooling system 1 according to one embodiment. The cooling system 1 is a cooling component for an IT device having a main condenser and a secondary condenser. Specifically, Figure 2 The cooling system is shown to cool IT equipment 5a to 5n using both the main heat transfer circuit and the secondary heat transfer circuit due to the main valve 13 being at least partially open. This is shown via the secondary return line 12, as indicated by dashed lines, and the secondary supply line 11, as indicated by solid lines. Thus, as described herein, in Figure 2 In the middle, the cooling system uses the cooling capacity of an additional auxiliary condenser 4 to cool the electronic rack that can operate under high power loads.

[0043] like Figure 1As shown, the cooling system 1 includes a pressure sensor 14 coupled to a secondary return line 12. In one embodiment, the pressure sensor 14 can be any type of sensor (e.g., a piezoelectric pressure sensor, a force collector-type sensor, a pressure sensor, etc.) configured to detect (or sense) changes in pressure (e.g., steam) within the secondary return line 12. Specifically, the pressure sensor senses the steam pressure (of the steam flowing through the secondary return line) and generates a corresponding electrical signal indicating the steam pressure within the line. However, in another embodiment, the pressure sensor can be located anywhere within any return line and / or return distribution manifold. As shown, and as described herein, the pressure sensor is communicatively coupled to one or more fans 16, a secondary valve 15, or both, based on the type of secondary condenser (e.g., via a control line 23, which may be wired).

[0044] In one embodiment, pressure sensor 14 may include processing elements (e.g., a processor, memory, etc.) and may be configured to adjust 1) the fan speed of (a plurality of) fans 16 or 2) the opening ratio of secondary valve 15 based on the sensed pressure. Specifically, the pressure sensor may be configured to sense steam pressure and may be configured to determine adjustment based on the sensed pressure. The pressure sensor may use the sensed pressure to perform a table lookup on a data structure that correlates steam pressure with fan speed and / or opening ratio. Upon determining adjustment, the pressure sensor may send a control signal to (a plurality of) fans(s) via control line 23 to change the fan speed, or send a control signal to the secondary valve to adjust the valve opening ratio (e.g., at least partially open). For example, the pressure sensor may increase the fan speed or increase the opening ratio as the steam pressure in the secondary return line increases to improve the cooling capacity of the secondary condenser. For example, when the fan speed increases, the cooling air flowing through the cooling coil increases, which improves heat transfer from the coil to the flowing air, thereby improving the cooling capacity of the secondary condenser.

[0045] In some implementations, the pressure sensor can activate a fan or (e.g., from a closed state) at least partially open the secondary valve 15 in response to sensing a vapor pressure (e.g., a second pressure threshold) greater than the pressure threshold at which the main valve 13 is open (e.g., a first pressure threshold). In one implementation, when the vapor pressure in the secondary return line 12 is maintained between the first and second pressure thresholds, the secondary heat transfer loop can rely on natural convection in the secondary condenser to condense the vapor into condensate (e.g., without using a fan to push ambient air through the cooling coils of the secondary condenser or without using the rack supply line 17 to supply liquid coolant to the secondary condenser). Thus, the cooling system uses natural convection to automatically and passively manage the additional heat generated by IT equipment when performing high-power workloads, achieved by using the secondary condenser to change the fluid phase and circulate the cooling liquid back to the cooling platform to extract heat energy from the IT components on which the cooling platform is mounted. In this way, the cooling system can provide additional phase change cooling without requiring additional power resources to operate the fan and without needing to draw liquid coolant from the cooling source to increase the cooling capacity of the secondary condenser.

[0046] In one implementation, the condenser can be positioned to facilitate phase change cooling of the electronics rack. For example, as shown, the main condenser and auxiliary condenser are positioned (e.g., along a vertical axis extending in the height direction of the electronics rack) above the IT equipment. By positioning the two condensers above the IT equipment, the cooling system utilizes gravity to draw steam generated by the cooling platform upwards, then allows the condensate to flow downwards back into the cooling platform. Thus, steam and liquid coolant can circulate through each (or at least one) of the main and auxiliary heat transfer loops without the use of mechanical devices that facilitate natural circulation. For example, the cooling system circulates steam without any steam pump (e.g., connected to any return line) and without any liquid pump (e.g., connected to any supply line). In one implementation, the auxiliary condenser is located above the main condenser because it can be used only during periods of high-power load on the rack to condense the steam.

[0047] Figure 3This is a block diagram illustrating another example of a cooling system 1 with a buffer 25 according to one embodiment. Specifically, the cooling system includes a buffer designed to store (or accumulate) liquid coolant. As shown, the buffer is coupled between the main supply line 9 and the supply distribution manifold 7, thus storing the liquid coolant (or condensate) supplied by the main condenser 3 and / or the auxiliary condenser 4. The stored liquid coolant is then supplied to the supply distribution manifold to be supplied to the cooling platforms 21a to 21n. In one embodiment, the buffer ensures that the heat transfer loop has sufficient liquid coolant to cool the cooling platforms. As shown, the buffer is located above the cooling platforms 21a to 21n. This ensures that a sufficient amount of liquid coolant always flows into the cooling platforms. In some embodiments, the buffer may be coupled elsewhere and / or the cooling system may include two or more buffers. For example, each condenser may be coupled to a corresponding buffer.

[0048] In one embodiment, components of the cooling system 1 can be connected to each other via connectors. For example, the main condenser may include a supply port with a connector configured to engage (or connect) to the main supply line 9. Similarly, the main condenser may include a return port with another connector connected to the main return line 10. In one embodiment, the connectors can be any type of connector that is detachably connected to each other, such as drip-free blind mating quick disconnects. In one embodiment, these connectors allow components to be detachably connected to each other. Therefore, components of the cooling system can be disassembled and replaced as needed. For example, the main supply line 9 and the main return line 10 can be disconnected (separated) from the main condenser to replace the condenser.

[0049] In one implementation, at least some of the return lines (e.g., lines 10, 12, and / or 20) may differ from at least some of the supply lines (e.g., lines 9, 11, and / or 19). For example, the diameter of the return lines may be larger than the diameter of the supply lines because the volume of vapor flowing through the return lines may be larger than the volume of liquid coolant flowing through the supply lines.

[0050] In one implementation, the supply and return lines can be made of any material. For example, the lines can be made of metals such as copper, polymers (e.g., EPDM rubber), and / or plastics.

[0051] In one implementation, the pipeline may be made of a flexible material such as rubber.

[0052] Figure 4 and Figure 5These are flowcharts of processes 30 and 40 for liquid cooling components used in IT equipment, according to some embodiments. (Refer to...) Figure 1 and 2 The cooling system 1 is described Figure 4 and Figure 5 In one embodiment, at least some operations of the process may be performed by the controller 6, the main valve 13, and / or the pressure sensor 14.

[0053] Process 30 begins with the controller determining the maximum power threshold (e.g., maximum power density) of the electronic rack (e.g., IT equipment installed within the electronic rack) (at block 31). Specifically, once the electronic rack is configured by filling it with IT equipment (e.g., servers are added to server slots within the rack), the controller can determine the configured maximum power density. As described herein, the controller can determine the configured maximum power density based on the power information of the equipment (e.g., power information may include power requirements, thresholds, etc.). For example, the equipment may be communicatively connected to the controller and send information when the equipment is installed. In another embodiment, the controller can retrieve this data based on the equipment's identification information (e.g., model number, etc.). The controller determines a pressure threshold based on at least one of the maximum power threshold and cooling capacity of the main condenser (at block 32). As described herein, the controller can determine the pressure threshold based on a comparison of the electronic rack's maximum power threshold and the main cooling capacity of the main condenser. The controller sets the opening pressure of the main valve 13 according to the pressure threshold (at block 33). In one embodiment, the controller sends a control signal to the main valve causing it to automatically open when the steam pressure exceeds the pressure threshold.

[0054] Controller 6 determines whether the steam pressure (e.g., the steam pressure within the main return line 10) exceeds a pressure threshold (at decision block 34). For example, the cooling system may include an additional pressure sensor communicatively coupled to the controller and configured to sense, for example, the steam pressure within the main return line 10. If the steam pressure (e.g., the steam pressure within the main return line 10) exceeds the pressure threshold, the controller opens the main valve (e.g., by transmitting a control signal via control line 22), causing both the main condenser and the auxiliary condenser to condense the steam into liquid coolant (at block 35). The controller determines whether the steam pressure within the auxiliary return line 12 exceeds (e.g., pressure) a threshold (at decision block 36). As described herein, pressure sensor 14 may sense the steam pressure within the auxiliary return line 12, and this pressure threshold may be different from (e.g., greater than) the pressure threshold that causes the main valve to open (at least partially). If the steam pressure in the secondary return line 12 exceeds the pressure threshold, the controller adjusts at least one of 1) the fan speed of one or more fans 16 and 2) the opening ratio of the secondary valve 15 (at box 37) based on the sensed steam pressure.

[0055] As described herein, the pressure threshold can be based at least on the maximum power threshold of the electronic rack and the main cooling capacity of the main condenser. However, these parameters can change over time. For example, the maximum power threshold may change due to changes in rack configuration (e.g., adding IT equipment and / or removing IT equipment from the electronic rack). Similarly, the main condenser may be replaced (e.g., due to repair or failure). Therefore, controller 6 can be configured to perform at least some operations of process 30 in response to changes in rack configuration. For example, in response to a change, the controller can perform at least the operations in blocks 31 to 33 to determine whether the pressure threshold has changed and set the opening pressure of the main valve accordingly. For example, the controller can determine a new maximum power threshold for the electronic rack based on changes in the electronic rack configuration (e.g., adding equipment with a higher power density to the electronic rack), determine a new pressure threshold based on the new power threshold, and set the opening pressure of the main valve accordingly. In another embodiment, the controller can periodically (e.g., at least daily, weekly, monthly, etc.) reassess the pressure threshold to ensure the cooling requirements of the electronic rack. As described herein, Figure 5 This is a flowchart of process 40 for a liquid coolant for an IT device according to one embodiment. Process 40 begins with controller 6 determining the vapor pressure within a main heat transfer loop. In the main heat transfer loop, a cooling platform mounted on the IT component is connected to a main condenser via 1) a main supply line and 2) a main return line. The main supply line supplies liquid coolant to the cooling platform, and the main return line returns vapor generated by the cooling platform to the main condenser (at box 41) as heat generated by the IT component is transferred to the liquid coolant via the cooling platform. In response to determining that the vapor pressure within the main heat transfer loop exceeds a pressure threshold, the controller opens a closed main valve. The main valve connects the main return line to a secondary condenser, which is connected to the main supply line via a secondary supply line. When the closed main valve opens, a secondary heat transfer loop is created, in which at least a portion of the vapor is condensed back by the secondary condenser to the liquid coolant supplied to the main supply line via the secondary supply line (at box 42). However, in response to determining that the steam pressure in the main heat transfer loop does not exceed the pressure threshold, the controller keeps the main valve closed, so that the steam is condensed back into the liquid coolant only through the main condenser (at box 43).

[0056] In one implementation, at least some of the operations described in processes 30 and 40 may be performed periodically. Specifically, cooling system 1 (e.g., controller 6 of cooling system 1) may perform at least some of these operations while the electronic rack is operating (e.g., as described herein, when one or more IT devices are processing data). For example, the operation of determining a pressure threshold based on a maximum power threshold may be performed periodically based on changes in the power requirements of one or more IT devices and / or changes in the cooling capacity of the main and auxiliary condensers. As described herein, the pressure threshold is based on the maximum power threshold or density of the electronic rack, which may be determined based on the device's specifications. In another implementation, the maximum power threshold may be based on the historical power density of the device during electronic rack operation over a period of time (e.g., a day, a week, a month, etc.). For example, during this period, the controller may determine the average power density drawn by the electronic rack that is less than the maximum power density. In one implementation, the controller may determine the pressure threshold based on the average power density.

[0057] Some implementations may perform variations of processes 30 and 40. For example, specific operations of the processes may not be performed in the exact order shown and described. Specific operations may not be performed in a consecutive sequence of operations, and different specific operations may be performed in different implementations. For example, as described herein, the operation of these processes is performed by the controller 6 of the cooling system 1. However, as described herein, in another implementation, other components may perform at least some of the operations. For example, at block 35, the main valve 13 may automatically open in response to a steam pressure exceeding a pressure threshold. As another example, at blocks 36 and 37, the pressure sensor 14 may determine whether the steam pressure in the secondary return line exceeds a pressure threshold and perform regulation accordingly.

[0058] As previously described, embodiments of this disclosure may be (or include) a non-transitory machine-readable medium (e.g., microelectronic memory) storing instructions thereon that program one or more data processing components (generally referred to herein as a "processor") to perform phase-change cooling operations, such as determining a pressure threshold and setting the opening pressure of a main valve based on that threshold. In other embodiments, some of these operations may be performed by specific hardware components including hard-wired logic. Alternatively, these operations may be performed by any combination of program data processing components and fixed hard-wired circuit components.

[0059] In the foregoing description, embodiments of the present disclosure have been described with reference to specific exemplary embodiments. It will be apparent that various modifications may be made thereto without departing from the broader spirit and scope of the present disclosure as set forth in the appended claims. Therefore, the description and drawings are to be considered illustrative rather than restrictive.

[0060] Although specific embodiments have been described and illustrated in the accompanying drawings, it should be understood that these embodiments are merely illustrative and not intended to limit the broad scope of this disclosure, and that this disclosure is not limited to the specific structures and arrangements shown and described, and various other modifications can be made thereto by those skilled in the art. Therefore, this specification is considered illustrative and not restrictive.

[0061] In some embodiments, this disclosure may include expressions such as "at least one of [element A] and [element B]". This expression may refer to one or more of the elements. For example, "at least one of A and B" may refer to "A", "B", or "A and B". Specifically, "at least one of A and B" may refer to "at least one of A and at least one of B" or "at least one of A or B". In some embodiments, this disclosure may include expressions such as "[element A], [element B], and / or [element C]". This expression may refer to any one element or any combination of elements. For example, "A, B, and / or C" may refer to "A", "B", "C", "A and B", "A and C", "B and C", or "A, B, and C".

Claims

1. A cooling system for an electronics rack, the cooling system comprising: a primary condenser; a primary feed line and a primary return line coupling the primary condenser to a cooling bench to create a primary heat transfer loop, the cooling bench arranged to be mounted on an information technology assembly of an information technology device, the information technology device disposed within the electronics rack, in the primary heat transfer loop the primary condenser 1) feeds liquid coolant to the cooling bench via the primary feed line and 2) receives vapor generated by the cooling bench via the primary return line as heat generated by the information technology assembly is transferred through the cooling bench into the liquid coolant; a secondary condenser coupled in parallel with the primary condenser; a secondary feed line coupling the secondary condenser to the primary feed line; a secondary return line coupling the secondary condenser to the primary return line; and a primary valve coupled to the secondary return line, wherein the secondary return line comprises a first portion coupled between the primary return line and the primary valve and a second portion coupled between the primary valve and the secondary condenser, wherein the primary valve is configured to at least partially open in response to a pressure of the vapor in the primary return line exceeding a pressure threshold, wherein in response to the primary valve at least partially opening a secondary heat transfer loop is created in which the secondary condenser receives at least a portion of the vapor in the primary return line via the secondary return line and condenses the at least a portion of the vapor back into liquid coolant fed to the primary feed line via the secondary feed line. 1) a fan arranged to move ambient air using cooling coils of the secondary condenser; or 2) a rack feed line and a rack return line coupling the secondary condenser with a cooling source and a secondary valve coupled with the rack feed line or the rack return line.

2. The cooling system of claim 1, further comprising: the pressure sensor is configured to: sense a vapor pressure within the secondary return line; and 3. The cooling system of claim 2, further comprising a pressure sensor coupled to the secondary return line and communicatively coupled to the fan or the secondary valve, wherein, adjust 1) a fan speed of the fan or 2) an opening ratio of the secondary valve based on the sensed pressure. the controller is configured to: determine the pressure threshold based on at least one of a maximum power threshold of the electronics rack and a cooling capacity of the primary condenser; and 4. The cooling system of claim 1, further comprising a controller coupled in communication with the main valve, wherein, set an opening pressure of the primary valve according to the pressure threshold.

5. The cooling system of claim 1, further comprising: a feed distribution manifold coupling the primary feed line to the cooling bench; and a return distribution manifold coupling the primary return line to the cooling bench.

6. The cooling system of claim 5, further comprising a liquid coolant buffer coupled between the primary feed line and the feed distribution manifold. the secondary condenser is located above the primary condenser, the primary condenser being located above the information technology device, wherein vapor and liquid coolant circulate through each of the primary heat transfer loop and the secondary heat transfer loop without any vapor pump and any liquid pump. the primary condenser is a first type of two-phase heat exchanger and the secondary condenser is a second type of two-phase heat exchanger.

9. An electronics rack comprising:

7. The cooling system of claim 1, wherein, ​ 8. The cooling system of claim 1, wherein, ​ ​ a plurality of information technology devices arranged in a stack for providing data processing services, each of the information technology devices including one or more processors; a primary condenser; a primary feed line and a primary return line coupling the primary condenser to a cooling deck to create a primary heat transfer loop, the cooling deck arranged to mount on a processor of an information technology device of the plurality of information technology devices, in the primary heat transfer loop the primary condenser 1) feeds liquid coolant to the cooling deck via the primary feed line and 2) receives vapor generated by the cooling deck via the primary return line as heat generated by the information technology assembly is transferred through the cooling deck into the liquid coolant; a secondary condenser coupled in parallel with the primary condenser; a secondary feed line coupling the secondary condenser to the primary feed line; a secondary return line coupling the secondary condenser to the primary return line; and a primary valve coupled to the secondary return line, wherein the secondary return line includes a first portion coupled between the primary return line and the primary valve and a second portion coupled between the primary valve and the secondary condenser, wherein the primary valve is configured to at least partially open in response to a pressure of the vapor in the primary return line exceeding a pressure threshold, wherein in response to the primary valve at least partially opening a secondary heat transfer loop is created in which the secondary condenser receives at least a portion of the vapor in the primary return line via the secondary return line and condenses the at least a portion of the vapor back into liquid coolant fed to the primary feed line via the secondary feed line. 1) a fan arranged to move ambient air using cooling coils of the secondary condenser; or 2) a rack feed line and a rack return line coupling the secondary condenser with a cooling source and a secondary valve coupled with the rack feed line or the rack return line.

10. The electronic rack of claim 9, further comprising: the pressure sensor is configured to: sense a vapor pressure within the secondary return line; and 11. The electronic rack of claim 10, further comprising a pressure sensor coupled to the secondary return line and communicatively coupled to the fan or the secondary valve, wherein, adjust 1) a fan speed of the fan or 2) an opening ratio of the secondary valve based on the sensed pressure. the controller is configured to: determine the pressure threshold based on at least one of a maximum power threshold of the electronic rack and a cooling capacity of the primary condenser; and 12. The electronic rack of claim 9, further comprising a controller communicatively coupled with the main valve, wherein, set an opening pressure of the primary valve according to the pressure threshold.

13. The electronic rack of claim 9, further comprising: a feed distribution manifold coupling the primary feed line to the cooling deck; and a return distribution manifold coupling the primary return line to the cooling deck.

14. The electronic rack of claim 13, further comprising a liquid coolant buffer coupled between the primary feed line and the feed distribution manifold. the secondary condenser is located above the primary condenser, the primary condenser being located above the plurality of information technology devices, wherein vapor and liquid coolant circulate through each of the primary heat transfer loop and the secondary heat transfer loop without any vapor pump and any liquid pump. ​ ​ 15. The electronic rack of claim 9, wherein, ​ 16. The electronic rack of claim 9, wherein, The primary condenser is a two-phase heat exchanger of a first type and the secondary condenser is a two-phase heat exchanger of a second type.

17. A method for liquid cooling an information technology assembly of information technology equipment installed within an electronic rack, the method comprising: determining a vapor pressure within a primary heat transfer loop in which a cooling station installed on the information technology assembly is coupled to a primary condenser by 1) a primary feed line and 2) a primary return line, wherein the primary feed line feeds liquid coolant to the cooling station and the primary return line returns vapor produced by the cooling station to the primary condenser as heat generated by the information technology assembly is transferred through the cooling station to the liquid coolant; opening a closed primary valve in response to determining that the vapor pressure within the primary heat transfer loop exceeds a pressure threshold, the primary valve coupling the primary return line to a secondary condenser, the secondary condenser coupled to the primary feed line by a secondary feed line, wherein a secondary heat transfer loop is created when the closed primary valve is opened in which the secondary condenser receives at least a portion of the vapor in the primary return line via a secondary return line, the at least a portion of the vapor being condensed by the secondary condenser back into liquid coolant fed to the primary feed line via the secondary feed line; and maintaining a closed state of the closed primary valve in response to determining that the vapor pressure within the primary heat transfer loop does not exceed the pressure threshold, such that the vapor in the primary return line is condensed back into liquid coolant only by the primary condenser, wherein the secondary condenser is coupled in parallel with the primary condenser, wherein the primary valve is coupled to the secondary return line, the secondary return line coupling the primary return line to the secondary condenser, the secondary return line including a first portion coupled between the primary return line and the primary valve and a second portion coupled between the primary valve and the secondary condenser.

18. The method of claim 17, wherein, the method further comprising: sensing a vapor pressure within the secondary return line; and adjusting 1) a fan speed of a fan arranged to move ambient air using cooling coils of the secondary condenser or 2) an opening ratio of a secondary valve coupling the secondary condenser to a liquid cooling source based on the sensed pressure.

19. The method of claim 17, further comprising: determining the pressure threshold based on at least one of a maximum power threshold of the electronic rack and a cooling capacity of the primary condenser; and setting an opening pressure of the primary valve according to the pressure threshold.

20. The method of claim 19, further comprising: determining a new maximum power threshold of the electronic rack based on a configuration change of the electronic rack; determining a new pressure threshold based on at least the new maximum power threshold; and setting an opening pressure of the primary valve according to the new pressure threshold.

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