System for cooling electronic devices in electronic module

Abstract

To provide a system and a method for efficiently cooling an electronic module.SOLUTION: A system for cooling a plurality of electronic devices has a first cooling circulator 20 that causes a first liquid coolant to circulate between a first electronic device 12 and a heat exchanger 18. The first electronic device is thermally coupled to the first liquid coolant. A second cooling circulator 22 causes a second liquid coolant to flow through the heat exchanger and to flow through cooling modules 14, 16 that are thermally coupled to a second electronic device and a third electronic device and arranged in parallel. The first cooling circulator and the second cooling circulator are thermally coupled via the heat exchanger such that the heat exchanger transfers heat from the first liquid coolant to the second liquid coolant.SELECTED DRAWING: Figure 3B

Description

[Technical Field]

[0001] The present disclosure relates to a system for cooling one or more electronic devices, the electronic devices being housed within an electronic module. The system includes first and second cooling circulation devices, where a coolant circulating within the first cooling circulation device is cooled by transferring heat to a coolant circulating within the second cooling circulation device via a heat exchanger. A method for cooling multiple electronic devices housed within an electronic module is further described. [Background technology]

[0002] Within a computer, server, or other device used for data processing (referred to as IT or information technology) are numerous electronic devices called integrated circuits (ICs). The electronic devices within an integrated circuit may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), a graphics processing unit (GPU), random access memory (RAM), etc. Each of these devices generates heat during use. It is important to transfer this heat outward from the device to maintain the device at an optimal temperature for proper operation. As the processing power of IT increases, and thus the number of electronic devices within computers, servers, or other IT, the challenge of removing sufficient heat generated by the electronic devices increases.

[0003] Generally, electronic devices mounted on a printed circuit board (PCB) are usually housed or enclosed in a case, housing, or chassis to form an electronic module. Computer servers often comprise multiple electronic modules mounted in racks and connected together to provide the necessary IT facilities. To maintain the electronic devices within the chassis at an appropriate temperature, a method is needed to remove heat from each case or chassis.

[0004] It is common to cool electronic modules by passing air over or through their respective cases or chassis. The airflow can be sufficient to remove some heat from inside the enclosure to the surrounding environment. Until recently, this cooling method has been used almost exclusively for mass-produced IT and server equipment. However, as technology shrinks in size for the same computing performance, it has been found that the heat generated by electronic devices increases even with a shrinking footprint. Thus, the peak performance of IT systems has been inhibited or limited by the limitations of cooling electronic modules with air-cooled systems.

[0005] Accordingly, more complex systems and methods have been proposed for cooling electronic modules. In some cases, liquid cooling is used, where a liquid coolant is flowed over or in close proximity to a heat sink coupled to the electronic device. Heat can then be transferred outward from the electronic device to an area or element where the heat can be removed from the liquid coolant. Liquid cooling can, in some cases, provide more efficient transfer of heat outward from the electronic device or component, and therefore can provide greater cooling power than air-cooled systems. However, prior art liquid cooling systems often require customized systems, which are complex and expensive to install. Furthermore, improvements in cooling performance are constantly desired. Summary of the Invention [Problem to be solved by the invention]

[0006] It is therefore an object of the present invention to provide a system for cooling electronic modules, as well as a method for cooling such a system, that overcomes these drawbacks of prior art systems. [Means for solving the problem]

[0007] With the above objectives in mind, a system for cooling multiple electronic devices housed within an electronic module housing or chassis is described. The system includes first and second cooling circulation devices through which respective first and second liquid coolants flow. Each circulation device receives heat transferred from one or more respective electronic devices housed within the electronic module. The first liquid coolant (or first cooling liquid) is cooled by transferring heat to a second liquid coolant in a heat exchanger. The second liquid coolant (or second cooling liquid) can be a facility-level supply, such as a chilled water supply.

[0008] Each of the cooling circulation devices is used to cool an electronic device among the multiple devices in the electronic module. However, the second cooling circulation device is further configured to cool the coolant circulating in the first cooling circulation system by exchanging heat between the first liquid coolant and the second liquid coolant via a heat exchanger. The second cooling circulation device can be configured in several different ways. In a first example of the second cooling circulation device, the cooling module and the heat exchanger (more specifically, the thermally conductive mating surfaces for heat transfer within the heat exchanger) are arranged in series between a first inlet of the second liquid coolant to the electronic module (through which the second liquid coolant with the lowest temperature passes) and a final outlet of the second liquid coolant from the electronic module (through which the second liquid coolant with the highest temperature passes), with the cooling module located before the heat exchanger. In a second example of the second cooling circulation device, the cooling module and the heat exchanger (more specifically, the thermally conductive mating surfaces for heat transfer within the heat exchanger) are arranged in series between a first inlet (through which the second liquid coolant with the lowest temperature passes) of the second liquid coolant to the electronic module and a final outlet (through which the second liquid coolant with the highest temperature passes) of the second liquid coolant from the electronic module, with the heat exchanger located before the cooling module. In a third example of the second cooling circulation device, the cooling module and the heat exchanger (more specifically, the thermally conductive mating surfaces for heat transfer within the heat exchanger) are arranged in parallel between a first inlet (through which the second liquid coolant with the lowest temperature passes) of the second liquid coolant to the electronic module and a final outlet (through which the second liquid coolant with the highest temperature passes) of the second liquid coolant from the electronic module. In a fourth example of the second cooling circuit, the cooling modules and thermally conductive interfaces for heat transfer within the heat exchanger are arranged in parallel between the inlet for the second liquid coolant to the electronic module (through which the second liquid coolant with the lowest temperature passes) and the outlet for the second liquid coolant from the electronic module (through which the second liquid coolant with the highest temperature passes). Both branches of the second cooling circuit pass through the body of the heat exchanger, which has an inlet and an outlet that are directly connected to (or act as) the inlet and outlet for the second liquid coolant from the electronic module.

[0009] Advantageously, the first example has been shown to provide greater cooling of a particular electronic device coupled to the cooling module compared to the second example. However, the second example has been found to provide greater cooling of the entire electronic module compared to the first example. The third example allows for balancing the cooling power in the cooling module compared to cooling of the first liquid coolant in the heat exchanger. The fourth example has all the advantages of the third example, e.g., for balancing the cooling power in the cooling module (and thus the cooling of devices thermally coupled to the cooling module and the cooling of devices thermally coupled to the first liquid coolant) compared to thermally conductive interfaces for heat transfer within the heat exchanger. However, the third example also provides a configuration with fewer joints and connectors, thereby increasing system reliability by reducing complexity and potential leak points.

[0010] For each of the examples described above, the first cooling circulation device may provide immersion cooling. In other words, a volume of first liquid coolant is contained within the chassis or housing of the electronic module. The first device is at least partially immersed in the volume of the first liquid coolant. The first cooling circulation apparatus circulates the first liquid coolant within the chassis or housing of the electronic module and through the heat exchanger (e.g., by a pump within the housing or chassis).

[0011] In certain examples, the respective locations of the electronic devices and cooling modules within the electronic module, as well as the volume of first liquid coolant, may be arranged such that when the system is in use, the liquid level of the volume of first liquid coolant contained within the housing or chassis is lower than that of the cooling module. In other words, under normal operation, the cooling module does not come into direct contact with the first liquid coolant. This has been found to improve the overall cooling power of the current system.

[0012] Thus, a combined or hybrid cooling system is disclosed that uses two cooling loops: a loop that circulates coolant through a cold plate coupled to a specific electronic device, and an immersion cooling loop to cool multiple partially submerged electronic devices. The cold plate provides higher-performance cooling than immersion cooling and focuses on cooling the hottest components. However, the cold plate must be directly mounted to each component to be cooled, making it impractical to mount a cold plate on every hot component within an electronic module. Therefore, the combined cooling approach provided by the described system provides cooling via the cold plate for the hottest components (typically the processor or GPU), while the remaining components are cooled via an immersion cooling approach using a dielectric coolant. Following this combined approach, using the cold plate to cool the hottest components and immersion cooling for the other components also allows for the appropriate selection of the lowest possible coolant level, rather than relying on a high fill level to fully submerge all elements within the electronic device. This saves weight and costs.

[0013] In a first aspect, there is provided a system for cooling a plurality of electronic devices, the electronic devices being contained within a housing of an electronic module, the system comprising: a first cooling circulation apparatus configured to circulate a first liquid coolant between a first electronic device of the plurality of electronic devices and the heat exchanger, the first electronic device being positioned to be thermally coupled to the first liquid coolant such that heat generated in the first electronic device is transferred to the first liquid coolant when the system is in use; a second cooling circulation apparatus configured to cause a second liquid coolant to flow through the heat exchanger and to cause the second liquid coolant to flow through a cooling module thermally coupled to a second electronic device of the plurality of electronic devices, wherein when the system is in use, heat generated by the second electronic device is transferred to the second liquid coolant through a surface of the cooling module; A system is described in which the first cooling circulation device and the second cooling circulation device are thermally coupled via a heat exchanger such that the heat exchanger is configured to transfer heat from the first liquid coolant to the second liquid coolant.

[0014] An electronic device may be any heat-generating device or component, including integrated circuits (ICs) including central processing units (CPUs), application specific integrated circuits (ASICs), graphics processing units (GPUs), random access memories (RAMs), etc. Devices may be connected together to form a server or other computer processing facility, or other IT.

[0015] An electronic module, or server module, may be a module that forms part of a computer server. An electronic module is a module in which each of the electronic devices is mounted in a chassis or house. The electronics module may have a casing. The electronics module may be configured to be mounted or installed within a rack. For example, the electronics module may conform to industry standard dimensions required to fit into a standard server rack (known as 1RU (one rack unit) or 1OU (one open unit)). Such a unit may be referred to as a blade server. However, the electronics module may be sized to fit into other types or sizes of server racks or may be made to custom sizes.

[0016] The system includes first and second cooling circulation devices (or first and second cooling loops) that provide arrangements for the flow of respective first and second coolants through the electronic modules.

[0017] Specifically, the first cooling circulation device provides a flow of a first liquid coolant. The first cooling circulation device may be entirely contained within the housing or chassis of the electronic module such that the first liquid coolant is circulated around and within the electronic module. Specifically, the first cooling circulation device circulates or flows the first liquid coolant between a heat exchanger (which may be located within the electronic module) and a first electronic heat-generating device (from which heat is absorbed by the first liquid coolant).

[0018] The first cooling circulation system may provide immersion cooling such that a pump circulates the first liquid coolant from a reservoir stored within the housing of the electronic module, through the pump and heat exchanger, and then flows near the first electronic device. Alternatively, the first cooling circulation system may store the first liquid coolant in a pipe or conduit for circulation between the heat exchanger and the first electronic device coupled to a cold plate or similar cooling module. In either case, the first liquid coolant is a closed loop in which the first liquid coolant circulates and is not replaced or replenished.

[0019] The second cooling circulation device provides a flow of a second liquid coolant. In particular, the second cooling circulation device causes the flow of the second liquid coolant from an inlet to the electronic module to an outlet to the electronic module through a heat exchanger and / or one or more cooling modules. The cooling modules may be cold plates or other modules for coupling to specific electronic heat-generating devices such that heat is transferred from the coupled electronic device to the second liquid coolant through the cooling modules. The heat exchanger acts to receive the heat transferred from the first liquid coolant.

[0020] The cooling module may be a specific component for efficient heat transfer from an electronic device (such as a second electronic device) to a second liquid coolant. The cooling module may be coupled to the second electronic device via a mounting surface of the cooling module such that heat is transferred from the second electronic device to the second liquid coolant via the mounting surface. The cooling module may be a cold plate, as described below.

[0021] In some cases, the second cooling circuit may be a closed loop (i.e., the liquid coolant is recirculated and recycled within the loop), but this is not always the case. Alternatively, the second cooling circuit may describe an open loop in which the liquid coolant is received, flows around the described path, and then sent to a drain. For example, after passing through the electronics module, the second liquid coolant in the second cooling circuit may then be cooled (by passing through a cooling system before passing back through the electronics module) or replenished (e.g., if the second liquid coolant is part of a facility-wide coolant supply, e.g., a facility water supply).

[0022] Advantageously, the system described is a hybrid system of two cooling circuits. The use of such a hybrid system allows for the use of a higher performance, more efficient cooling device, particularly for high temperature components (e.g., a second cooling circuit directed to cooling at least a second electronic device), as well as additional cooling devices for cooling other devices. However, rather than simply using two completely separate cooling systems in parallel, the inventors recognize that a higher performance cooling device can also be used to remove heat from the other cooling device. To some extent, the first cooling circuit can be considered nested with the second cooling circuit.

[0023] Optionally, the first liquid coolant is a dielectric liquid and the second liquid coolant is water. Although the term liquid coolant is used herein, it will be understood that any suitable fluid coolant may be used.

[0024] Optionally, the second cooling circulation device is configured to cause the second liquid coolant to flow through the heat exchanger and from the heat exchanger through the cooling module when the system is in use. More specifically, the flow is from a thermally conductive interface for heat transfer from the first cooling liquid to the second cooling liquid in the heat exchanger. In this configuration, the heat exchanger (or the thermally conductive interface for heat transfer in the heat exchanger) and the cooling module are arranged in series within the second cooling circulation device. In particular, considering the flow of the second liquid coolant within the electronic module, the second liquid coolant is caused to flow from the heat exchanger (or from the thermally conductive interface for heat transfer in the heat exchanger) toward the cooling module. In other words, the second liquid coolant flows from the heat exchanger to the cooling module between the initial inlet of the second liquid coolant to the electronic module (when the second liquid coolant has the lowest temperature) and the final outlet of the second liquid coolant from the electronic module (when the second liquid coolant has the highest temperature). This configuration demonstrates a slight reduction in cooling performance in the cooling module because the second liquid coolant has already received heat from the first liquid coolant through the heat exchanger. However, the first liquid coolant is cooled through the heat exchanger with the second liquid coolant that has just entered the electronics module (and is therefore at its lowest temperature and has not been preheated by the cooling module), thus providing better overall cooling of the electronics module. This configuration appears to provide improved overall cooling performance and may be particularly useful for electronics modules with numerous high-temperature auxiliary components on their PCBs (mounted within the electronics module housing and cooled via the first cooling circuit).

[0025] Alternatively, the second cooling circulation device is configured to cause the second liquid coolant to flow through the cooling module and from the cooling module through the heat exchanger. More specifically, the flow is from the cooling module to the thermally conductive interface for heat transfer from the first cooling liquid to the second cooling liquid in the heat exchanger. In this configuration, the heat exchanger (or the thermally conductive interface for heat transfer in the heat exchanger) and the cooling module are arranged in series within the second cooling circulation device. In particular, when considering the flow of the second liquid coolant within the electronic module, the second liquid coolant flows from the cooling module toward the heat exchanger (or toward the thermally conductive interface for heat transfer in the heat exchanger). In other words, the second liquid coolant flows from the cooling module to the heat exchanger between the initial inlet of the second liquid coolant to the electronic module (when the second liquid coolant has the lowest temperature) and the final outlet of the second liquid coolant from the electronic module (when the second liquid coolant has the highest temperature). Beneficially, this system provides higher cooling performance in the cooling module because the second liquid coolant is supplied directly to the cooling module prior to the heat exchanger. This configuration may be useful in electronic modules where the main processor (or equivalent) operates at a very high temperature and auxiliary components on the PCB operate at a relatively low temperature. This configuration may also be used in systems where processor performance is a particular concern.

[0026] Alternatively, the heat exchanger and the cooling module are arranged on a parallel branch of the second cooling circuit. The second cooling circulation device is configured to flow the second liquid coolant through the heat exchanger and flow the second liquid coolant through the cooling module in parallel, so that the second liquid coolant flows through the heat exchanger and the cooling module in parallel. More specifically, the second cooling circulation device is configured to bring the second liquid coolant into contact with the thermally conductive interface in the first branch for heat transfer from the first cooling liquid to the second cooling liquid in the heat exchanger, and to flow through the cooling module in the second branch. In other words, considering the flow of the second liquid coolant through the electronic module, the second liquid coolant flows through the cooling module in parallel with the flow through the heat exchanger. Beneficially, this arrangement may provide better control of the flow of the second liquid coolant through the electronic module, since the flow through the heat exchanger can be balanced against the flow directly through the cooling module.

[0027] Preferably, the housing is configured to store a first liquid coolant, and when the system is in use, the first electronic device is at least partially immersed in the first liquid coolant stored in the housing. In other words, the first cooling circulation device is an immersion cooling device. Heat can be transferred directly to the first liquid coolant from a surface of the first electronic device that is at least partially immersed in the first liquid coolant.

[0028] In contrast, the second cooling circulation apparatus may be configured to circulate a second liquid coolant through a cooling module and a heat exchanger (specifically, a thermally conductive interface for heat transfer in the heat exchanger), with the cooling module coupled to a second electronic device on the mounting surface of the cooling module. Heat is thus exchanged between the second electronic device and the second liquid coolant via the mounting surface of the second cooling module. The cooling module forming part of the second cooling circulation apparatus is described in more detail below.

[0029] Preferably, the first cooling circulation device is completely contained within the housing, in other words, the first cooling circulation device is positioned such that the first liquid coolant does not leave the confines of the housing or chassis of the electronic module during normal operation.

[0030] The first cooling circuit may be at least partially isolated from the second cooling circuit except for a heat exchanger to which the first and second cooling circuits are thermally coupled, to avoid increasing the temperature of the second liquid coolant except in certain areas of the cooling device and heat exchanger in order to maximize the cooling power (or more specifically, the temperature gradient) in the cooling device and heat exchanger.

[0031] Preferably, the housing is configured to store a volume of a first liquid coolant that fills the housing to a liquid level when the system is in use, the cooling module is positioned within the housing so that it is above the liquid level of the first liquid coolant, and the first electronic device is positioned within the housing so that it is at least partially immersed in the volume of first liquid coolant stored within the housing. In other words, when the system is in use, the sides and top of the cooling module do not come into contact with the first liquid coolant. Preferably, the cooling module is not immersed or partially immersed in the first liquid coolant. Preferably, the majority of the heat exchange between the first liquid coolant and the second liquid coolant occurs within the heat exchanger, such that the first and second liquid coolants are substantially thermally uncoupled except at the heat exchanger. Providing heat exchange only at the heat exchanger provides greater control over the temperatures of the second (and first) liquid coolants in different elements of each circulation system, thus providing a temperature gradient for heat exchange in each element. The overall first liquid coolant level can be very low, ensuring minimal contact with the exterior walls of the cooling module. In some cases, the first liquid coolant level can be so low that it does not contact the cooling module at all. As such, this provides a cost-effective and simple method for preventing heat transfer from the first liquid coolant to the second liquid coolant through the cooling module. Provide a solution.

[0032] Preferably, the heat exchanger includes at least a first chamber and a second chamber separated from each other by a thermally conductive interface, and the heat exchanger is configured for the flow of a first liquid coolant through at least the first chamber and the flow of a second liquid coolant through at least the second chamber, such that heat is transferred from the first liquid coolant to the second liquid coolant through the thermally conductive interface. The heat exchanger is a dedicated element configured for heat exchange between the first liquid coolant and the second liquid coolant. Each of the first liquid coolant and the second liquid coolant may pass through one or more respective chambers of the heat exchanger, and heat may be transferred from the first liquid coolant to the second liquid coolant through the thermal interface between the chambers. The heat exchanger may have any suitable design and may provide multiple chambers and multiple thermal interface surfaces to improve the efficiency of heat exchange. Fins or other protrusions may be provided on the thermal interface to increase the surface area of ​​the thermal interface and promote the efficiency of heat exchange between the first and second liquid coolants. Optionally, the heat exchanger is a plate heat exchanger. Optionally, a specific configuration for the heat exchanger having two or more paths through the second chamber may be used, with some of the paths not contacting the second liquid coolant or preventing the second liquid coolant from flowing across the thermally conductive interface. Thus, only the second liquid coolant in some of the paths through the second chamber receives heat transferred from the first liquid coolant.

[0033] Preferably, the heat exchanger is disposed within the housing of the electronic module. In particular, the heat exchanger is housed within the electronic module. This allows at least the first liquid coolant to be completely contained within the electronic module. This reduces the complexity of connections into and out of the electronic module. This may also allow the electronic module to be provided as a sealed module, which may be advantageous if the second liquid coolant is a dielectric, which may be harmful to humans if released from the module, and which may be expensive to replace if leaked or lost.

[0034] Preferably, the first cooling circuit further comprises a weir, the weir comprising: a base and a retaining wall extending from the base, the base and the retaining wall defining a volume for storing a portion of the first liquid coolant; a weir inlet through which the first liquid coolant enters the volume; An entry of sufficient first liquid coolant into the volume through the weir inlet causes the first liquid coolant to overflow the retaining wall to collect with the first liquid coolant stored within the housing of the electronics module and external to the weir. Alternatively, the base and the retaining wall extending from the base further comprise one or more holes such that an entry of sufficient first liquid coolant into the volume through the weir inlet causes the first liquid coolant to flow through the one or more holes to collect with the first liquid coolant stored within the housing of the electronics module and external to the weir.

[0035] The base and retaining wall may provide a reservoir or "bath" into which the first liquid coolant can overflow. Alternatively, holes may be provided in the base or retaining wall through which the first liquid coolant can flow. The weir may be coupled to a surface of the first electronic device to act as a heat sink for the first electronic device. Alternatively, the first electronic device may be disposed inside the volume of the weir. In either case, the weir provides a volume for pooling or retaining liquid coolant for the heat-generating electronic device. Alternatively, or additionally, the weir may be mounted on a PCB elevated relative to other components within the electronic device and / or relative to the level of the first coolant within the cavity of the housing of the electronic module. In this way, the first liquid coolant acts to overflow or flow from the weir over the first electronic device and any other electronic devices or components housed within the electronic module.

[0036] The weir is configured to direct the flow of the first liquid coolant circulating through the first cooling circulation device. In other words, the weir can be configured to allow the first liquid coolant overflowing or spilling from the weir to flow onto or over the particular electronic device housed within the electronic module. Advantageously, by including a weir in the first cooling circulation system, the liquid coolant can be more effectively applied to the location(s) where the most heat is generated. Thus, less coolant can be used. Because coolant is expensive and heavy, reducing the volume of coolant can improve flexibility, efficiency, and reliability (e.g., because coolant leaks are less likely and the volume of coolant can withstand momentary temperature changes caused by the failure of other components in the system). Reducing the overall liquid level of the first coolant within the housing of the electronic module also allows for separation between the first liquid coolant and the cooling module, as discussed elsewhere.

[0037] With respect to the weir, a volume for storing or holding a first liquid coolant may be defined by a base and a retaining wall (which may be integral or separate). The base is the portion of the weir that may be mounted on top of an electronic device (more specifically, a heat transfer surface of the electronic device) or to which the electronic device within the weir may be attached. In this manner, the base acts to transfer heat from the heat transfer surface. The base typically has a flat surface that defines the volume (and the base itself may be flat in shape). Heat transferred (typically conducted) through the base (particularly its surface that defines the volume) is transferred to the liquid coolant stored within the volume. The retaining wall extends from the base.

[0038] One effect of the weir is to raise the level of the coolant stored within the weir volume above the level of the primary liquid coolant reservoir within the electronic module (at least when the cooling module is operated with the plane of the electronic devices and / or circuit board horizontal). The weir can be on a raised PCB, rising above the primary liquid coolant within the electronic module's housing. The primary liquid coolant flow that forms the weir then cools all other components as it returns to the pump inlet. The raised weir heat sink means that the coolant fill level can be just sufficient to cover any electronic devices mounted on the electronic module. In this way, the amount of coolant within the cooling module's container can be lower than the height of the retaining wall, achieving a lower liquid level for the primary liquid coolant reservoir.

[0039] Preferably, the weir inlet includes a nozzle device for directing the first liquid coolant flowing into the volume. The nozzle device may include one or more nozzles (which may be push-fit), each of which directs the flowing or pumped first liquid coolant into a respective portion of the weir volume, particularly a portion of the weir base. Each of the one or more nozzles may be located in the base, in the retaining wall, or at an upper portion of the volume to direct the first liquid coolant into the volume. For example, each nozzle may direct the flowing or pumped liquid coolant into a respective portion of the weir volume adjacent to a portion of a heat transfer surface of the electronic device having a maximum temperature or a temperature above a threshold level (i.e., one of the hottest portions of the device). Most preferably, the nozzle device directs the flowing or pumped liquid coolant in a direction perpendicular to the weir base. This forces the coolant directly into the volume, which may improve heat dissipation.

[0040] Preferably, the weir further comprises protrusions (such as pins and / or fins) extending from the base (or retaining wall) within the volume. The protrusions may cause the liquid coolant to spread radially away from a predetermined point on the surface of the base (e.g., coincident with the hottest portion of the electronic device). In particular, the protrusions may be formed in a non-linear pattern.

[0041] Preferably, the dam is coupled to a surface of the first electronic device, or the first electronic device is positioned within a volume of the dam, so as to act as a heat sink.

[0042] Preferably, the first cooling circulation system further includes a pump configured to circulate the first liquid coolant through the first cooling circulation system. The pump may be positioned to receive the first liquid coolant from a reservoir of liquid coolant stored within the electronic module, with at least the first electronic device at least partially immersed. The pump may then move the received first liquid coolant to another region of the electronic module, for example, a heat exchanger, and then to the inlet of the weir. The pump may be at least partially immersed in the first liquid coolant, which also assists in cooling the pump.

[0043] Preferably, the first cooling circulation device further comprises a pump inlet arranged to receive the first liquid coolant stored within the housing of the electronic module and external to the weir, in other words, the first liquid coolant stored within the electronic module is received by the pump inlet and delivered to the pump.

[0044] Preferably, the first cooling circulation system further comprises at least first and second pipes arranged to transport the first liquid coolant from the pump to the heat exchanger and from the heat exchanger to the weir inlet, respectively.

[0045] Preferably, the cooling module comprises a cold plate having a cold plate housing, the surface of the cold plate housing being arranged to provide a thermal interface for cooling a second electronic device thermally coupled thereto, and at least one channel within the cold plate housing and adjacent to the surface of the cold plate housing, the at least one channel being arranged for a second liquid coolant to flow through such that heat received from the second electronic device through the surface of the cold plate housing is transferred to the second liquid coolant.

[0046] Advantageously, the cold plate provides an efficient and effective mechanism for cooling a particular electronic device within an electronic module. The cold plate provides high performance cooling to a second electronic device to which it is thermally coupled. Thus, the cold plate can be coupled to the hottest component(s) within an electronic module to provide excellent targeted cooling power to those components.

[0047] Optionally, a surface of the cold plate housing may be directly coupled to a surface of the second electronic device. Alternatively, the housing may be coupled by an additional mating surface or component. Nevertheless, the cold plate and second electronic device are thermally coupled to facilitate effective and efficient heat transfer from the second electronic device to the second liquid coolant.

[0048] Two or more cold plates may be disposed within the electronic module as part of the second cooling circuit, and the two or more cold plates may be arranged in parallel or in series in the second cooling circuit, or if three or more cold plates are used, a combination of parallel and series configurations may be implemented.

[0049] Preferably, the second cooling circulation device further comprises a plurality of conduits arranged to transport the second liquid coolant between the cooling module, the heat exchanger, and any external cooling system or coolant supply external to the electronic module.

[0050] Optionally, the second cooling circulation device further comprises a cooling system, the second cooling circulation device transmitting a second liquid coolant between the cooling module, a heat exchanger (or more specifically, a thermally conductive interface of the heat exchanger) within the electronic device, and the cooling system (external to the electronic module). The cooling system removes heat from the second liquid coolant through the cooling system. In other words, the second cooling circulation device forms a closed loop in which the second liquid coolant received from the electronics module is cooled by the cooling system before being returned to the electronics module.

[0051] Alternatively, the second cooling circulation device is connected to a second liquid coolant supply, and the second cooling circulation device is configured to circulate the second liquid coolant received from the second liquid coolant supply between the cooling module in the electronic device and the heat exchanger (or more specifically, the thermally conductive interface in the heat exchanger) and then return to the second liquid coolant supply. In other words, the second cooling circulation device is open-loop, and the second liquid coolant is supplied from a facility-level supply and is constantly replenished. For example, the second liquid coolant supply may be a water supply, from which water (as the second liquid coolant) is received, circulated through the second cooling circulation device, and then exit the second cooling circulation device to a facility drain.

[0052] In a second aspect, a method for cooling a plurality of electronic devices, the electronic devices being contained within a housing of an electronic module, the system comprising: circulating a first liquid coolant through a first cooling circulation apparatus, the first liquid coolant including circulating the first liquid coolant between a first electronic device of the plurality of electronic devices and a heat exchanger, the first electronic device being positioned to be thermally coupled to the first liquid coolant such that heat generated in the first electronic device is transferred to the first liquid coolant; transporting the second liquid coolant around a second cooling circulation apparatus, the transport including flowing the second liquid coolant through a heat exchanger and flowing the second liquid coolant through a cooling module thermally coupled to a second electronic device of the plurality of electronic devices, wherein heat generated by the second electronic device is transferred to the second liquid coolant through a surface of the cooling module; A method is described in which the first cooling circulation device and the second cooling circulation device are thermally coupled via a heat exchanger such that heat is transferred from the first liquid coolant to the second liquid coolant via the heat exchanger.

[0053] In other words, the method may include circulating a first liquid coolant through a first cooling circuit and circulating a second liquid coolant through a second cooling circuit. Each of the first and second cooling circuits is configured to cool at least the respective first and second electronic devices. Furthermore, the second cooling circuit is configured such that the second liquid coolant receives heat transferred from the first liquid coolant via a heat exchanger. Advantageously, this hybrid cooling system provides the benefits of a high-performance cooling system associated with the hottest component (the second cooling circuit for the second electronic device), but then uses a further cooling system to cool other components within the electronic module. In particular, it may be impractical to provide a targeted cooling system (such as that provided by the second cooling circuit) for every component within the electronic module; therefore, the first cooling circuit can provide additional cooling for the remaining components to reduce the temperature of the general environment within the electronic module.

[0054] It will be understood that features described above with respect to a system can also be considered to be disclosed with respect to a method for cooling a plurality of electronic devices contained within an electronic module housing. Any property or advantage of a feature described above (with respect to a system) can also be considered to apply to a corresponding feature in relation to a method, as described below.

[0055] Preferably, transporting the second liquid coolant through the second cooling circuit includes flowing the second liquid coolant through the heat exchanger and from the heat exchanger through the cooling module when the system is in use. More specifically, the flow is from a thermally conductive interface for heat transfer through the cooling module from the first cooling liquid in the heat exchanger to the second cooling liquid. In other words, when considering the flow of the second liquid coolant within the electronic module, the second liquid coolant flows from the heat exchanger (or the thermally conductive interface for heat transfer in the heat exchanger) to the cooling module. This configuration provides better overall cooling of the electronic module (albeit at the expense of some cooling power in the cooling module).

[0056] Preferably, transporting the second liquid coolant through the second cooling circuit includes flowing the second liquid coolant through the cooling module and from the cooling module through a heat exchanger. More specifically, the flow is from the cooling module to a thermally conductive interface for heat transfer from the first cooling liquid to the second cooling liquid in the heat exchanger. In other words, when considering the flow of the second liquid coolant within the electronic module, the second liquid coolant flows from the cooling module to the heat exchanger (or to a thermally conductive interface for heat transfer in the heat exchanger). This configuration provides maximum cooling power to any electronic device directly coupled to the cooling module.

[0057] Preferably, the heat exchanger and the cooling module are arranged on parallel branches of the second cooling circuit, and transporting the second liquid coolant around the second cooling circuit includes flowing the second liquid coolant through the heat exchanger and flowing the second liquid coolant in parallel through the cooling module. More specifically, transporting the second liquid coolant around the second cooling circuit includes flowing the second liquid coolant on a first branch that contacts the thermally conductive interface for heat transfer from the first cooling liquid to the second cooling liquid in the heat exchanger and on a second branch through the cooling module. In other words, considering the flow of the second liquid coolant within the electronic module, the second liquid coolant flows in parallel through the heat exchanger to flow through the cooling module. Beneficially, this configuration allows for balancing the flow of the second liquid coolant through the cooling module compared to the heat exchanger.

[0058] Preferably, the housing is configured to store a first liquid coolant, and the first electronic device is at least partially immersed in the first liquid coolant stored in the housing. In other words, the housing of the electronic device stores a reservoir of the first liquid coolant in which the first electronic device (and possibly other electronic devices) are at least partially immersed. Thus, heat is transferred directly to the first liquid coolant from a surface of the first electronic device or other device at least partially immersed in the first liquid coolant. The housing may be a sealable chassis for storing the first liquid coolant. A volume or reservoir of the first liquid coolant is stored in the housing of the electronic module, and the electronic module at least partially fills a cavity enclosed within the chassis. In this way, the first liquid coolant is in direct contact with the at least partially immersed electronic device so that heat can be transferred from the electronic device to the first liquid coolant.

[0059] Preferably, the housing is configured to store a volume of a first liquid coolant that fills the housing to a liquid level, the cooling module is positioned within the housing so that it is above the liquid level of the first liquid coolant, and the first electronic device is positioned within the housing so that it is at least partially immersed in the first liquid coolant stored within the housing. In other words, the first liquid coolant does not contact the top or sides of the cooling module. Ideally, the cooling module does not have to be in direct contact with the first liquid coolant. Preferably, the cooling module is thermally decoupled from the first liquid coolant.

[0060] The heat exchanger may include at least first and second chambers separated by a thermal interface, and the heat exchanger is configured for flow of a first liquid coolant through at least the first chamber and a second liquid coolant through at least the second chamber, such that heat is transferred from the first liquid coolant to the second liquid coolant via the thermal interface. The heat exchanger is a specific element configured for efficient transfer of heat between the first liquid coolant and the second liquid coolant. The heat exchanger may have any suitable design for allowing separate flow of the first and second liquid coolants and exchanging heat therebetween. Optionally, the heat exchanger is a plate heat exchanger. Optionally, a specific configuration for the heat exchanger may be used that has two or more paths through the second chamber, some of which do not contact the second liquid coolant or prevent the second liquid coolant from flowing across the thermally conductive interface.

[0061] Preferably, the heat exchanger is located within or housed within the housing of the electronic module, which advantageously prevents the first liquid coolant from exiting the electronic module, both reducing the complexity of connections in the housing of the electronic module and reducing the risk of leakage or loss of the first liquid coolant.

[0062] Preferably, the cooling module may be mounted on or coupled to a surface of the second electronic device. The cooling module may provide a mechanism for indirectly transferring heat from the second electronic device to the second liquid coolant via the cooling module (in other words, the second liquid coolant does not directly contact the surface of the second electronic device; instead, heat is transferred from the second electronic device through a portion of the cooling module and received in the second liquid coolant). The cooling module may provide higher cooling power and may support more efficient cooling of the coupled electronic device than could otherwise be provided by the first cooling circulation apparatus.

[0063] In a preferred example, providing a cooling module in the second cooling circuit device includes providing a cold plate, the cold plate comprising: a cold plate housing, the cold plate housing having a surface positioned to provide a thermal interface for cooling a second electronic device thermally coupled to the cold plate housing; and at least one channel within the cold plate housing and proximate to a surface of the cold plate housing, the at least one channel being arranged such that a second liquid coolant flows through the at least one channel such that heat received through the surface of the cold plate housing from a second electronic device is transferred to the second liquid coolant.

[0064] Two or more cold plates may be provided, which may be arranged in parallel or in series within the second cooling circuit, and the surface of the cold plate housing may be directly bonded to the surface of the second electronic device or may be bonded via a mating surface to facilitate effective heat transfer.

[0065] The method may further include providing a plurality of conduits or pipes within the second cooling circulation device arranged to transport a second liquid coolant between the cold plate, the heat exchanger, and the cooling system.

[0066] Preferably, the first cooling circuit device may include a weir. a base and a retaining wall extending from the base, the base and the retaining wall defining a volume for storing a portion of the first liquid coolant; an inlet through which the first liquid coolant flows into the volume; A sufficient inflow of the first liquid coolant into the volume through the inlet causes the first liquid coolant to overflow the retaining wall and into the liquid coolant contained within the electronic module housing and external to the weir. Alternatively, the base and the retaining wall extending from the base further comprise one or more apertures such that entry of sufficient first liquid coolant into the volume through the weir inlet causes the first liquid coolant to flow through the one or more apertures and collect with the first liquid coolant contained within the housing of the electronic module and external to the weir.

[0067] Advantageously, the weir acts to promote flow of the first liquid coolant within the electronic module. The weir may be further positioned to direct the flow of the first liquid coolant circulating through the first cooling circulation device to particular electronic components.

[0068] In a particular example, the base of the weir can be thermally coupled to a first electronic device. The first electronic device is positioned within the volume of the weir. In this manner, the weir acts as an effective heat sink for the first electronic device. The weir also maintains a flow of a first liquid coolant that can cool heat-generating components disposed around the first electronic device to which the weir is coupled.

[0069] The inlet may further comprise a nozzle arrangement for directing the first liquid coolant into the volume, the nozzle arrangement comprising one or more nozzles.

[0070] The weir may further comprise a protrusion extending from the base and / or a retaining wall within the volume of the weir.

[0071] The method may further include providing a pump within the first cooling circulation device, the pump configured to circulate the first liquid coolant around the first cooling circulation device. The first cooling circulation device may further include a pump inlet for receiving the first liquid coolant housed within the housing of the electronic module and external to the weir.

[0072] The method may further include providing a plurality of pipes within the first cooling circulation device arranged to transport the first liquid coolant from the pump to the heat exchanger and from the heat exchanger to the inlet of the weir, respectively.

[0073] Preferably, the second cooling circuit further comprises a cooling system, and transporting the second liquid coolant around the second cooling circuit comprises transporting the second liquid coolant to the cooling module, to a heat exchanger (or a thermally conductive interface in the heat exchanger), and to the cooling system, where heat is removed from the second liquid coolant by the cooling system. The cooling system may be external to the electronic module and configured to transfer heat out of the second liquid coolant. For example, the cooling system may comprise a heat exchanger for transferring heat to a further (third) liquid coolant or medium.

[0074] Alternatively, the second cooling circulation device may further include a second liquid coolant supply, and transporting the second liquid coolant around the second cooling circulation device may include receiving the second liquid coolant from the second liquid coolant supply, transporting the second liquid coolant to a second electronic device of the plurality of electronic devices and to a heat exchanger (or a thermally conductive interface of the heat exchanger), and then returning the second liquid coolant to the second liquid coolant supply. For example, the second liquid coolant may be water, and the second cooling circulation device may be connected to a facility's water supply. Once the water has been circulated through the second cooling circulation device, it may be allowed to be sent to a drainage system (and thus not be recirculated through the second cooling circulation device).

[0075] In a third aspect, there is provided a system for cooling a plurality of electronic devices, the electronic devices being contained within a housing of an electronic module, the system comprising: a first cooling circulation device configured to circulate a first liquid coolant between a first electronic device of the plurality of electronic devices and a first chamber of the heat exchanger, the first electronic device circulating a first liquid coolant between the first electronic device and a first chamber of the heat exchanger, the first electronic device circulating a first liquid coolant between the first electronic device and a first chamber of the heat exchanger, the first electronic device circulating a first liquid coolant between the first electronic device and a first chamber of the heat exchanger, the first liquid coolant ... a first cooling circulation device arranged to be thermally coupled to the first liquid coolant such that the generated heat is transferred to the first liquid coolant; a second cooling circulation apparatus configured to cause a second liquid coolant to flow through a second chamber of the heat exchanger and to cause the second liquid coolant to flow through a cooling module thermally coupled to a second electronic device of the plurality of electronic devices, wherein, when the system is in use, heat generated by the second electronic device is transferred to the second liquid coolant through a surface of the cooling module; The system includes a first cooling circulation device and a second cooling circulation device that are thermally coupled via a thermally conductive interface separating the first and second chambers of the heat exchanger such that, during use, the heat exchanger is configured to transfer heat from a first liquid coolant in the first chamber to a second liquid coolant in the second chamber via the thermally conductive interface.

[0076] Further, as in the systems described above, in this system, the first cooling circulation system provides an arrangement for the flow of a first cooling liquid. In particular, the first cooling liquid may circulate or flow completely within the housing or chassis of the electronic module. The flow may be between a thermally conductive interface in the first chamber of the heat exchanger and the first electronic heat-generating device. The first electronic heat-generating device may be at least partially immersed in the first liquid coolant such that the housing or chassis of the electronic module acts as a reservoir or bath for the first liquid coolant. In this arrangement, the first liquid coolant is circulated around the reservoir from the first electronic device to the heat exchanger (more specifically, the thermally conductive interface in the heat exchanger) by use of a pump.

[0077] The second cooling circulation device provides an arrangement for the flow of a second liquid coolant. The second cooling circulation device causes the flow of the second liquid coolant to the cooling module and through a thermally conductive interface in the second chamber of the heat exchanger. The second cooling liquid receives heat transferred from an electronic device coupled to the cooling module and receives heat from the first liquid coolant through the thermally conductive interface.

[0078] A cooling module is a specific component that provides efficient heat transfer from an electronic device to a second liquid coolant without the second liquid coolant directly contacting the electronic device. The cooling module can be a cold plate having channels for the second liquid coolant to pass through. The surface of the cold plate can be mounted or coupled to the surface of the electronic device so that heat can pass through the coupled surface.

[0079] The system uses a heat exchanger having at least first and second chambers separated, at least in part, by a thermally conductive interface. A first liquid coolant is arranged to flow through the first chamber as part of a first cooling circuit, and a second liquid coolant is arranged to flow through the second chamber as part of a second cooling circuit. As the liquid coolant flows across or contacts the thermally conductive interface, heat is transferred from the hotter liquid to the colder liquid. By this mechanism, heat is transferred from the first liquid coolant to the second liquid coolant through the thermally conductive interface. The heat exchanger can be a plate heat exchanger. The plate heat exchanger can have a typical design, or a design described below, with six inlet / outlet ports and / or at least two channels through one of the chambers (such as the second chamber).

[0080] Advantageously, the system described is a hybrid or nested system of two cooling circuits. The use of such a hybrid system allows for the use of a more powerful and efficient cooling circuit, particularly for high temperature components (e.g., a second cooling circuit for cooling at least a second electronic device), as well as additional cooling circuits for cooling other devices. The system may be used to control various components within an electronic module. It provides a mechanism for energy-efficient cooling of various heat-generating components and is space-efficient within the housing volume of the electronic module.

[0081] Optionally, the first liquid coolant is a dielectric liquid and the second liquid coolant is water. Although the term liquid coolant is used herein, it will be understood that any suitable fluid coolant may be used.

[0082] Preferably, the second cooling circulation device is configured to cause the second liquid coolant to flow through the second chamber of the heat exchanger and from the second chamber of the heat exchanger through the cooling module when the system is in use. Preferably, the second cooling circulation device is configured to cause the second liquid coolant to flow from the thermally conductive interface of the second chamber of the heat exchanger to the cooling module when the system is in use. In other words, the second cooling circulation device comprises a thermally conductive interface in the second chamber of the heat exchanger (where heat is transferred from the first liquid coolant) and a cooling module arranged in series. In this arrangement, the thermally conductive interface in the heat exchanger precedes the cooling module in the direction of flow of the second liquid coolant. While this arrangement slightly reduces the cooling power of the cooling module (because the temperature of the second liquid coolant passing through the cooling module is higher compared to the other previously described arrangements), this arrangement provides particularly efficient cooling for the first liquid coolant. This configuration may be particularly useful for electronic modules that have many high temperature auxiliary components on a PCB (mounted within the electronic module housing and cooled via the first cooling circuit).

[0083] Alternatively, the second cooling circulation device is configured to flow the second liquid coolant through the cooling module and from the cooling module through the second chamber of the heat exchanger when the system is in use. Preferably, the second cooling circulation device is configured to flow the second liquid coolant from the cooling module to the thermally conductive mating surfaces in the second chamber of the heat exchanger when the system is in use. In other words, the second cooling circulation device is configured to arrange the thermally conductive mating surfaces in the cooling module and the second chamber of the heat exchanger (to which heat is transferred from the first liquid coolant) in series. In this arrangement, the cooling module precedes the thermally conductive mating surfaces in the heat exchanger in the direction of flow of the second liquid coolant. Beneficially, this system provides higher cooling performance in the cooling module. This configuration may be useful in electronic modules where the main processor (or equivalent) operates at a very high temperature and auxiliary components on the PCB operate at a relatively low temperature.

[0084] Alternatively, the thermally conductive interfaces of the cooling module and the heat exchanger are arranged on parallel first and second branches of the second cooling circuit, and the second cooling circuit is configured to flow the second liquid coolant through the first branch of the second cooling circuit, which includes the cooling module, and flow the second liquid coolant through the second branch of the second cooling circuit, which includes the thermally conductive interfaces of the heat exchanger. In other words, the thermally conductive interfaces of the cooling module and the heat exchanger are arranged in parallel. This configuration can, for example, allow balancing the cooling power of the second cooling circuit between the cooling module and the cooling of the first liquid coolant when different ratios of the second liquid coolant pass through each branch of the second cooling circuit. Furthermore, in this configuration, both the cooling module and the thermally conductive interfaces receive the second liquid coolant at its lowest temperature, thus providing maximum cooling power for each unit.

[0085] Preferably, the heat exchanger comprises a plurality of paths through the second chamber, a first branch of the second cooling circuit configured to cause the second liquid coolant to flow through a first path through the second chamber of the heat exchanger and through the cooling module, and a second branch of the second cooling circuit configured to cause the second liquid coolant to flow through a second path through the second chamber of the heat exchanger. The second cooling circuit is configured to allow the heat to flow across the thermally conductive interface through the first liquid coolant. In an example, both branches of the second cooling circuit pass through the body of the heat exchanger, and more specifically, through the second chamber of the heat exchanger, but only one branch passes through or contacts the thermally conductive interface within the heat exchanger. Thus, only one branch directly receives heat transferred from the first liquid coolant through the thermally conductive interface. This configuration allows for a more space-efficient use of the heat exchanger within the volume of the electrical module housing or chassis.

[0086] Preferably, the first path through the second chamber of the heat exchanger does not flow across a thermally conductive interface, i.e., the second path flows across a thermally conductive interface so that the second liquid coolant flowing through the second path receives heat from the first liquid coolant, but the second liquid coolant flowing through the first path does not receive heat directly from the first liquid coolant through the thermally conductive interface.

[0087] Preferably, the housing is configured to store a first liquid coolant, and when the system is in use, the first electronic device is at least partially immersed in the first liquid coolant stored within the housing. In other words, the first cooling circulation device is arranged so that the first liquid coolant does not leave the boundaries of the electronic module housing or chassis during normal operation. The first liquid coolant can be a reservoir within the electronic module housing, in which the first electronic device is at least partially immersed. Partial immersion allows direct contact between the first liquid coolant and the first device and efficient heat transfer therebetween.

[0088] The first cooling circuit may be at least partially isolated from the second cooling circuit except for a thermally conductive interface of the heat exchanger where the first and second cooling circuits are thermally coupled, to avoid increasing the temperature of the second liquid coolant except in certain areas of the cooling module and heat exchanger in order to maximize the cooling power (or more specifically, the temperature gradient) in the cooling module and heat exchanger.

[0089] Preferably, the housing is configured to store a volume of a first liquid coolant that fills the housing to a liquid level when the system is in use, the cooling module is positioned within the housing so that it is above the liquid level of the first liquid coolant, and the first electronic device is positioned within the housing so that it is at least partially immersed in the first liquid coolant stored within the housing. In other words, the sides and top of the cooling module do not come into contact with the first liquid coolant when the system is in use. Preferably, the cooling module is not immersed or partially immersed in the first liquid coolant. Preferably, the majority of the heat exchange between the first liquid coolant and the second liquid coolant occurs within the heat exchanger, such that the first and second liquid coolants are substantially thermally decoupled except at the heat exchanger. Providing heat exchange only at the heat exchanger provides greater control over the temperature of the second (and first) liquid coolant at different elements of each circulation system, thus providing a temperature gradient for heat exchange at each element. The overall first liquid coolant level can be very low, minimizing contact with the outer walls of the cooling module. In some cases, the first liquid coolant level may be so low that it does not contact the cooling module at all, thus providing a cost-effective and simple solution for preventing heat transfer from the first liquid coolant to the second liquid coolant through the cooling module.

[0090] Preferably, the first cooling circuit further comprises a weir, the weir comprising: a base and a retaining wall extending from the base, the base and the retaining wall defining a volume for storing a portion of the first liquid coolant; a weir inlet through which the first liquid coolant enters the volume; Sufficient flow of the first liquid coolant into the volume through the weir inlet causes the first liquid coolant to The weir is then allowed to overflow the wall and collect with the first liquid coolant stored within the housing of the electronics module and external to the weir. Alternatively, the base and the retaining wall extending from the base further comprise one or more holes such that entry of sufficient first liquid coolant into the volume through the weir inlet causes the first liquid coolant to flow through the one or more holes and collect with the first liquid coolant stored within the housing of the electronics module and external to the weir.

[0091] The base and retaining wall may provide a reservoir or "bath" into which the first liquid coolant can overflow. Alternatively, holes may be provided in the base or retaining wall through which the first liquid coolant can flow. The weir may be coupled to a surface of the first electronic device to act as a heat sink for the first electronic device. Alternatively, the first electronic device may be disposed inside the volume of the weir. In either case, the weir provides a volume for pooling or retaining liquid coolant for the heat-generating electronic device. Alternatively, or additionally, the weir may be mounted on a PCB elevated relative to other components within the electronic device and / or relative to the level of the first coolant within the cavity of the housing of the electronic module. In this way, the first liquid coolant acts to flow over the first electronic device and any other electronic devices or components housed within the electronic module as it overflows or flows from the weir.

[0092] The weir can be configured to direct the flow of the first liquid coolant circulating through the first cooling circulation apparatus. In other words, the weir can be configured to allow the first liquid coolant overflowing or spilling from the weir to flow onto or over a particular electronic device housed within the electronic module. Advantageously, including a weir in the first cooling circulation apparatus allows the liquid coolant to be more effectively applied to the location(s) where the most heat is generated. Thus, less coolant can be used. Because coolant is expensive and heavy, reducing the amount of coolant can improve flexibility, efficiency, and reliability (e.g., because coolant leaks are less likely and the volume of coolant can withstand momentary temperature changes caused by the failure of other components in the system). Reducing the overall liquid level of the first coolant within the electronic module housing also allows for separation between the first liquid coolant and the cooling module, as discussed elsewhere.

[0093] With respect to the weir, a volume for storing or holding a first liquid coolant may be defined by a base and a retaining wall (which may be integral or separate). The base is the portion of the weir that may be mounted on top of an electronic device (more specifically, a heat transfer surface of the electronic device) or to which the electronic device within the weir may be attached. In this manner, the base acts to transfer heat from the heat transfer surface. The base typically has a flat surface that defines the volume (and the base itself may be flat in shape). Heat transferred (typically conducted) through the base (particularly its surface that defines the volume) is transferred to the liquid coolant stored within the volume. The retaining wall extends from the base.

[0094] One effect of the weir is to raise the level of the coolant stored within the weir volume above the level of the primary liquid coolant reservoir within the electronic module (at least when the cooling module is operated with the plane of the electronic devices and / or circuit board horizontal). The weir can be on a raised PCB, rising above the primary liquid coolant within the electronic module's housing. The primary liquid coolant flow that forms the weir then cools all other components as it returns to the pump inlet. The raised weir heat sink means that the coolant fill level can be just sufficient to cover any electronic devices mounted on the electronic module. In this way, the amount of coolant within the cooling module's container can be lower than the height of the retaining wall, achieving a lower liquid level for the primary liquid coolant reservoir.

[0095] Preferably, the weir inlet includes a nozzle arrangement for directing the first liquid coolant flowing into the volume. Further, the nozzle device may include one or more nozzles (which may be push-type), each of which directs the flowing or pumped first liquid coolant into a respective portion of the weir's volume, particularly a portion of the weir's base. Each of the one or more nozzles may be located within the base, within the retaining wall, or at an upper portion of the volume to direct the first liquid coolant into the volume. For example, each nozzle may direct the flowing or pumped liquid coolant into a respective portion of the weir's volume adjacent to a portion of the heat transfer surface of the electronic device having a maximum temperature or a temperature above a threshold level (i.e., one of the hottest portions of the device). Most preferably, the nozzle device directs the flowing or pumped liquid coolant in a direction perpendicular to the weir's base. This may force the coolant directly into the volume, improving heat dissipation.

[0096] Preferably, the weir further comprises protrusions and / or retaining walls extending from the base within the volume of the weir. The protrusions may cause the liquid coolant to spread radially away from a predetermined point on the surface of the base (e.g., coincident with the hottest portion of the electronic device). In particular, the protrusions may be formed in a non-linear pattern.

[0097] Preferably, the dam is coupled to a surface of the first electronic device, or the first electronic device is positioned within a volume of the dam, so as to act as a heat sink.

[0098] Preferably, the first cooling circulation system further includes a pump configured to circulate the first liquid coolant through the first cooling circulation system. The pump may be positioned to receive the first liquid coolant from a reservoir of liquid coolant stored within the electronic module, with at least the first electronic device at least partially immersed. The pump may then move the received first liquid coolant to another region of the electronic module, such as a heat exchanger, and then to the inlet of the weir. The pump may be at least partially immersed in the first liquid coolant, which also assists in cooling the pump.

[0099] Preferably, the first cooling circulation device further comprises a pump inlet arranged to receive the first liquid coolant stored within the housing of the electronic module and external to the weir, in other words, the first liquid coolant stored within the electronic module is received by the pump inlet and delivered to the pump.

[0100] Preferably, the cooling module comprises a cold plate having a cold plate housing, the surface of the cold plate housing being arranged to provide a thermal interface for cooling a second electronic device thermally coupled thereto, and at least one channel within the cold plate housing and adjacent to the surface of the cold plate housing, the at least one channel being arranged for a second liquid coolant to flow through such that heat received from the second electronic device through the surface of the cold plate housing is transferred to the second liquid coolant.

[0101] Advantageously, the cold plate provides an efficient and effective mechanism for cooling a particular electronic device within an electronic module. The cold plate provides high performance cooling to a second electronic device to which it is thermally coupled. Thus, the cold plate can be coupled to the hottest component(s) within an electronic module to provide excellent targeted cooling power to those components.

[0102] Optionally, a surface of the cold plate housing may be directly coupled to a surface of the second electronic device. Alternatively, the housing may be coupled by an additional mating surface or component. Nevertheless, the cold plate and second electronic device are thermally coupled to facilitate effective and efficient heat transfer from the second electronic device to the second liquid coolant. are combined.

[0103] Two or more cold plates may be disposed within the electronic module as part of the second cooling circuit, and the two or more cold plates may be arranged in parallel or in series with one another in the second cooling circuit, or if three or more cold plates are used, a combination of parallel and series configurations may be implemented.

[0104] Preferably, the heat exchanger is disposed within the housing of the electronic module. In other words, the body of the heat exchanger, particularly the thermally conductive interface where heat exchange between the first and second cooling liquids occurs, is positioned entirely inside the housing or chassis of the electronic module. This means that the first cooling liquid does not leave or exit the volume of the housing of the electronic module, which may prevent leakage or loss of the first cooling liquid. In some examples, the inlet and outlet ports of the heat exchanger may be the inlet and outlet ports of the second liquid coolant into the housing, and therefore (only) these ports of the heat exchanger may extend through the wall of the housing of the electronic module.

[0105] Preferably, the heat exchanger includes at least a first chamber and a second chamber separated from each other by a thermally conductive interface, and the heat exchanger is configured for flow of a first liquid coolant through the at least first chamber and a second liquid coolant through the at least second chamber such that heat is transferred from the first liquid coolant to the second liquid coolant via the thermally conductive interface. The heat exchanger may be a plate heat exchanger. The plate heat exchanger provides efficient heat exchange between the liquid coolant in the first chamber and the liquid coolant in the second chamber. The plate heat exchanger may have a conventional structure, as described below, or may have additional inlet or outlet ports in one or both of the first and second chambers.

[0106] Preferably, the heat exchanger comprises two or more inlets and / or two or more outlets in the second chamber. The inlets may be injection ports or inlet ports, and the outlets may be outlet ports or outlet ports. The heat exchanger may comprise two inlets and two outlets in the second chamber. Thus, in this example, the heat exchanger has a total of six inlets and outlets (the first chamber also has an inlet and an outlet). Optionally, two or more inlets and / or two or more outlets may be provided in at least one or more of the first or second chambers.

[0107] The second chamber may have a first path and a second path for the second liquid coolant to flow therethrough. Paths may be thought of as pathways or passages through the chamber with specific starting points (inlets) and ending points (outlets). Different pathways have different combinations of starting points (inlets) and ending points (outlets), but some of the individual inlets and outlets may be shared or common to the different pathways. Each chamber of the heat exchanger may be thought of as a region that is fluidly connected and fluidly isolated from any other chamber. While different pathways through the chambers are fluidly connected, particular pairs of pathways through the same chamber do not necessarily meet or intersect at any point (instead, they meet via another pathway within the same chamber).

[0108] Preferably, at least one of the two or more inlets and / or outlets is common to the first and second paths through the second chamber. In other words, the first and second paths may, for example, have a common inlet but separate outlets. In a beneficial example, this allows the second liquid coolant to pass through a heat exchanger but have parallel branches to be routed to a cooling module or flow across a thermally conductive interface. For example, a first path may proceed from a first inlet to a first outlet of the second chamber, then direct the first liquid coolant towards the cooling module, while a second path may direct the second liquid coolant towards a first outlet of the second chamber. In yet another example, the second chamber may include a third pathway that receives return second liquid coolant from the cooling module at a second inlet to the second chamber and then directs the first liquid coolant out a second outlet from the second chamber (the second outlet being common to the second and third pathways).

[0109] Preferably, the first pathway has an inlet or outlet in common with the second pathway, and another inlet or outlet that is not in common with the second pathway, For example, the first and second pathways may meet at either a common inlet or outlet, but then proceed to different and separate respective outlets or inlets.

[0110] Preferably, the relative flow rates of the second liquid coolant through the first and second paths are determined by a pressure gradient across an inlet or outlet in the first path that is not common to the second path. For example, a relative pressure change or drop at the first and second outlets to the second chamber can determine the flow rates through the first and second outlets and the first and second paths. In this manner, the proportion of the second liquid coolant passing through each path in the second chamber can be adjusted.

[0111] Preferably, the pressure gradient across the inlet or outlet in the first pathway not common to the second pathway is determined by the size of the aperture of the inlet or outlet in the first pathway not common to the second pathway, the aperture being the opening through which the second liquid coolant flows into or out of the second chamber. The size of the aperture may be varied by using an orifice plate or by substituting a different size nozzle at the inlet or outlet. For example, the aperture of a first outlet connected to the first pathway via a heat exchanger may be smaller than the aperture of a second outlet connected to the second pathway via a heat exchanger, resulting in a lower flow rate through the first pathway than through the second pathway.

[0112] Preferably, the flow rate of the second liquid coolant through the first path is less than the flow rate of the second liquid coolant through the second path. Preferably, the flow rate of the second liquid coolant through the first path is 50% or less of the flow rate of the second liquid coolant through the second path. Preferably, the flow rate of the second liquid coolant through the first path is 35% or less of the flow rate of the second liquid coolant through the second path. In other words, the flow rate through the first path (discharged to the cooling module) is less than the flow rate through the second path (contacting or passing through the thermally conductive interface in the heat exchanger). This changes the ratio of the second liquid coolant delivered to the cooling module compared to the thermally conductive interface. This, in turn, improves the cooling performance at the thermally conductive interface compared to the cooling module. In one example, approximately 20% of the volume of the second liquid coolant entering the heat exchanger is routed through the cooling module and approximately 80% of the volume of the second liquid coolant entering the heat exchanger is routed through the thermally conductive interface, although different ratios can be used.

[0113] Optionally, the second cooling circulation device further comprises a cooling system, wherein the second cooling circulation device is configured to circulate the second liquid coolant between the cooling module, a heat exchanger (or more specifically, a thermally conductive interface of the heat exchanger) in the electronic device, and the cooling system (external to the electronic module). The cooling system removes heat from the second liquid coolant via the cooling system. In other words, the second cooling circulation device forms a closed loop in which the second liquid coolant received from the electronic module is cooled by the cooling system before being returned to the electronic module.

[0114] Alternatively, the second cooling circulation device is connected to a second liquid coolant supply, and the second cooling circulation device distributes the second liquid coolant received from the second liquid coolant supply to the electronic device. The second cooling circuit is configured to circulate the second liquid coolant through the cooling modules and heat exchangers (more specifically, the thermally conductive interface surfaces in the heat exchangers) and then return it to the second liquid coolant supply. In other words, the second cooling circuit is open loop, and the second liquid coolant is supplied from a facility-level supply and is constantly replenished. For example, the second liquid coolant supply may be a water supply, from which water is received (as the second liquid coolant), circulated through the second cooling circuit, and then exits the second cooling circuit to a facility drain.

[0115] The properties of features described above with respect to the system also apply to similar or corresponding features of the method. Any property or advantage of a feature described above (with respect to the system) can also be considered to apply to the corresponding feature in relation to the method, as described below.

[0116] In a fourth aspect, there is provided a method for cooling a plurality of electronic devices, the electronic devices being contained within a housing of an electronic module, the system comprising: circulating a first liquid coolant through a first cooling circulation apparatus, the first liquid coolant including circulating the first liquid coolant between a first electronic device of the plurality of electronic devices and a first chamber of a heat exchanger, the first electronic device being positioned to be thermally coupled to the first liquid coolant such that heat generated in the first electronic device is transferred to the first liquid coolant; transporting the second liquid coolant around a second cooling circulation apparatus, the transport including flowing the second liquid coolant through a second chamber of the heat exchanger and flowing the second liquid coolant through a cooling module thermally coupled to a second electronic device of the plurality of electronic devices, wherein heat generated by the second electronic device is transferred to the second liquid coolant through a surface of the cooling module; The first cooling circulation device and the second cooling circulation device are thermally coupled via a thermally conductive interface separating the first and second chambers of the heat exchanger such that heat from the first liquid coolant in the first chamber of the heat exchanger is transferred to the second liquid coolant in the second chamber of the heat exchanger via the thermally conductive interface.

[0117] The method provides a hybrid system for cooling incorporating two coolant loops, where a first loop cools a first electronic device and a second loop cools a second electronic device (via a cooling module) similar to the liquid coolant in the first loop. The described system provides an efficient mechanism for cooling and allows for centralized cooling (via a cooling module in the second loop) of certain electronic devices that may generate more heat.

[0118] Preferably, transporting the second liquid coolant around the second cooling circuit includes flowing the second liquid coolant through the second chamber of the heat exchanger and from the second chamber of the heat exchanger through the cooling module, more specifically, the second liquid coolant flows serially from the thermally conductive mating surfaces of the second chamber of the heat exchanger and then to the cooling module.

[0119] Preferably, transporting the second liquid coolant around the second cooling circuit includes flowing the second liquid coolant through and from the cooling module through the second chamber of the heat exchanger. More specifically, the second liquid coolant flows serially through the cooling module and then through thermally conductive mating surfaces in the second chamber of the heat exchanger.

[0120] Preferably, the thermally conductive interface of the cooling module and the heat exchanger is arranged on parallel first and second branches of the second cooling circuit, and transporting the second liquid coolant around the second cooling circuit comprises: flowing the second liquid coolant through a first branch of the second cooling circuit comprising the cooling module; and transporting the second liquid coolant around a thermally conductive interface of the heat exchanger. and flowing the cooling water through a second branch of a second cooling circuit having a conductive interface.

[0121] Preferably, the heat exchanger comprises a plurality of paths through the second chamber, and transporting the second liquid coolant around the second cooling circulation device comprises flowing the second liquid coolant through a first branch of the second cooling circulation device comprising a first path through the second chamber of the heat exchanger and the cooling module, and flowing the second liquid coolant through a second branch of the second cooling circulation device comprising a second path through the second chamber of the heat exchanger across the thermally conductive interface.

[0122] Preferably, the first path through the second chamber of the heat exchanger does not flow across the thermally conductive interface.

[0123] Preferably, about 30% or less of the second liquid coolant passes through the first path and 70% or more of the second liquid coolant passes through the second path.

[0124] Preferably, the housing is configured to store a first liquid coolant, and the first electronic device is at least partially immersed in the first liquid coolant stored within the housing.

[0125] Preferably, the housing is configured to store a volume of a first liquid coolant that fills the housing to a liquid level, the cooling module is positioned within the housing so as to be above the liquid level of the first liquid coolant, and the first electronic device is positioned within the housing so as to be at least partially immersed in the first liquid coolant stored within the housing.

[0126] In a fifth aspect, there is provided a heat exchanger comprising: at least a first chamber and a second chamber, the first chamber and the second chamber being separated from one another by a thermally conductive interface, the heat exchanger being configured for a flow of a first liquid coolant through the at least first chamber and a flow of a second liquid coolant through the at least second chamber such that heat is transferred from the first liquid coolant to the second liquid coolant through the thermally conductive interface; The heat exchanger includes two or more inlets and / or two or more outlets in at least one of the first or second chambers. The inlets may be injection or inlet ports, and the outlets may be exhaust or outlet ports. In an example, the second chamber has two inlet ports and two exhaust ports, and the first chamber has an inlet port and an exhaust port, so that the heat exchanger has six ports in total.

[0127] Preferably, one or more chambers having two or more inlets and / or outlets further include two or more paths for liquid coolant passing through the respective chambers. For example, a chamber may have a first path and a second path for passing a second liquid coolant. Paths can be thought of as passages or pathways through the chamber with specific starting points (inlets) and ending points (outlets). Different paths have different combinations of starting points (inlets) and ending points (outlets), but some individual inlets and outlets may be shared or common to different paths. Each chamber of the heat exchanger can be thought of as a region that is fluidly connected within the chamber but fluidly isolated from other chambers. While different paths through the chambers are fluidly connected, pairs of specific paths through the same chamber do not necessarily converge or intersect at any point (instead, they converge via other paths within the same chamber).

[0128] Preferably, at least one of the two or more inlets and / or outlets is common to two or more of the two or more paths. Preferably, at least one of the two or more paths has one of the inlets or outlets that is common to at least one other of the two or more paths and the other of the inlets or outlets that is not common to any other of the two or more paths. In an example, the first path and the second path may have a common inlet but separate outlets, for example. For example, the first path may proceed from a first inlet to a first outlet of the chamber, while the second path may proceed from the first inlet of the chamber and then direct the first liquid coolant out a second outlet. In yet another example, the chamber may include a third path that receives a second liquid coolant at a second inlet to the chamber and then directs the first liquid coolant out a second outlet from the chamber (the second outlet being common to the second and third paths). Only one or some of the paths may lead to or contact a thermally conductive mating surface in the heat exchanger.

[0129] Preferably, at least one of the two or more paths has a different flow rate than another of the two or more paths. For example, the different paths may have different flow rates of liquid coolant therethrough. This allows different proportions of liquid coolant entering the heat exchanger chamber to pass through different paths, and therefore different proportions of liquid coolant to pass out different outlets.

[0130] Preferably, the flow rate through at least one of the two or more paths is determined by a pressure gradient across an inlet or outlet that is not common to any other of the two or more paths. For example, the first and second paths may have a common inlet but separate outlets. The flow rate through each of the first and second paths may be determined by the relative pressure (or pressure drop) at each of the separate outlets.

[0131] Preferably, the pressure gradient across an inlet or outlet that is not common to any other of the two or more paths is determined by the size of an aperture in the inlet or outlet that is not common to any other of the two or more paths, the aperture being an opening through which liquid coolant flows into or out of the chamber. The size of the aperture may be changed by substituting a nozzle in the outlet or by using an orifice plate. A larger aperture in the outlet allows a larger flow rate therethrough. Thus, a first path having a smaller aperture in the outlet compared to an outlet in a second path causes the first path to have a lower flow rate than the second path.

[0132] Preferably, the rate of heat transfer from the first liquid coolant to the second liquid coolant through the thermally conductive interface is slower in one of the two or more paths than in another of the two or more paths, and preferably the rate of heat transfer in one of the two or more paths is no more than 50% of the rate of heat transfer through another of the two or more paths.

[0133] Preferably, at least one of the paths does not contact or flow across a thermally conductive interface in the heat exchanger. Preferably, one of the two or more paths has a flow rate that is less than the flow rate through another of the two or more paths that contacts the thermally conductive interface where heat is transferred from the first liquid coolant to the second liquid coolant. In other words, the proportion of liquid coolant entering the heat exchanger chamber that is able to pass through the thermally conductive interface may be greater than the proportion of liquid coolant that does not pass through the thermally conductive interface. Preferably, the flow rate through one of the two or more paths that contacts the thermally conductive interface is less than half the flow rate through another of the two or more paths that contacts the thermally conductive interface.

[0134] Preferably, one of the two or more paths is common to another of the two or more paths. and the other of the two or more paths is not common to another of the two or more paths, and the flow rate through one of the two or more paths is determined by a pressure gradient across the inlet or outlet that is not common to another of the two or more paths. As discussed above, the relative sizes of the apertures in the separate inlets or outlets in the different paths determine the change in fluid pressure at the outlet and therefore the relative flow rate through each path.

[0135] In a sixth aspect, there is provided a heat exchanger comprising: There is a heat exchanger having six ports, where the ports are a combination of inlet and outlet ports. The heat exchanger may be a plate heat exchanger. The heat exchanger may have a first chamber through which a first liquid coolant flows and a second chamber through which a second liquid coolant flows, and the first and second chambers may be separated by a thermally conductive interface. Heat may pass through the thermally conductive interface from the first liquid coolant to the second liquid coolant or from the second liquid coolant to the first liquid coolant depending on a temperature gradient across the thermally conductive interface. The six ports may be arranged across each of the first and second chambers, and each of the first and second chambers has at least one inlet port and at least one outlet port.

[0136] Preferably, the six ports include three inlet ports and three outlet ports. The three inlet ports and three outlet ports may be disposed across each of the first and second chambers, each of the first and second chambers having at least one inlet port and at least one outlet port.

[0137] Preferably, the heat exchanger comprises at least a first chamber and a second chamber, the first chamber and the second chamber separated from one another by a thermally conductive interface, and the heat exchanger is configured for flow of a first liquid coolant through at least the first chamber and a second liquid coolant through at least the second chamber, such that heat is transferred from the first liquid coolant to the second liquid coolant via the thermally conductive interface.

[0138] Preferably, two of the inlet ports are for injecting the second liquid coolant into the second chamber and two of the outlet ports are for expelling the second liquid coolant from the second chamber.

[0139] Preferably, the second chamber includes at least two paths for the second liquid coolant therethrough. A path can be thought of as a passage or a pathway through the chamber with a specific starting point (inlet) and ending point (outlet). Different paths have different combinations of starting points (inlet) and ending points (outlet), but some of the individual inlets and outlets may be shared or common to the different paths. Each chamber of the heat exchanger can be thought of as a region that is fluidly connected within the chamber but fluidly isolated from any other chamber. While different paths through the chamber are fluidly connected, particular pairs of paths through the same chamber do not necessarily meet or intersect at any point (instead, they meet via another path within the same chamber).

[0140] Preferably, the second chamber comprises three paths for the second liquid coolant to pass through, the second liquid coolant flowing on a first path proceeding from a first inlet port to a first outlet port, the second liquid coolant flowing on a second path proceeding from the first inlet port to a second outlet port, and the second liquid coolant flowing on a third path proceeding from the second inlet port to a second outlet port.

[0141] Preferably, only the second path flows across a thermally conductive interface in the heat exchanger. The second path does not cross the thermally conductive interface when flowing between the first inlet port and the second outlet port. Flowing beyond.

[0142] Preferably, the flow rate of the second liquid coolant through the first path is less than the flow rate of the second liquid coolant through the second path. In other words, the flow rate over the second path through the thermally conductive interface may be different from, or optionally less than, the flow rate through the first path. This allows different ratios and volumes of coolant to pass through the different paths and thus to come into contact with the thermally conductive interface in the heat exchanger.

[0143] Preferably, the flow rate is determined by the change in pressure at the first outlet port. The flow rate may be determined by the change in pressure at the first outlet port relative to the second outlet port.

[0144] Preferably, the pressure change at the first outlet port is determined by the size of the aperture or opening through the first outlet port, which may be adjusted by the use of an orifice plate or by interchangeable nozzles having different sizes at one or both of the first and second outlet ports.

[0145] Preferably, the size of the aperture or opening of the first outlet port is smaller than the size of the aperture or opening of the second outlet port, such that the flow rate (in terms of volume of cooling liquid per unit time) through the first outlet port (and thus through the first path of the second chamber) is less than the flow rate through the second outlet port (and thus through the second path of the second chamber).

[0146] In a further aspect, there is provided a system for cooling a plurality of electronic devices as described in the third aspect above, wherein the heat exchanger comprises the heat exchanger of the fifth or sixth aspect. The heat exchanger of the sixth aspect may have a configuration that is particularly suitable for use in the system of the third aspect or the method of the fourth aspect.

[0147] The numbered sections below provide examples only.

[0148] 1. A system for cooling a plurality of electronic devices contained within an electronic module housing, the system comprising: a first cooling circulation apparatus configured to circulate a first liquid coolant between a first electronic device of the plurality of electronic devices and the heat exchanger, the first electronic device being thermally coupled to the first liquid coolant such that heat is transferred from the first electronic device to the first liquid coolant; a second cooling circulation apparatus configured to circulate a second liquid coolant between a second electronic device of the plurality of electronic devices and the heat exchanger, the second electronic device being thermally coupled to the second liquid coolant such that heat is transferred from the second electronic device to the second liquid coolant; A system in which the first cooling circulation device and the second cooling circulation device are thermally coupled via at least a heat exchanger such that heat is transferred from the first liquid coolant to the second liquid coolant via the heat exchanger.

[0149] 2. The system described in item 1, wherein the second cooling circulation device further comprises a cooling system, and the second cooling circulation device is configured to circulate a second liquid coolant between a second electronic device of the plurality of electronic devices, a heat exchanger, and the cooling system, and heat is removed from the second liquid coolant by the cooling system.

[0150] 3. A second cooling circulation device is connected to the second liquid coolant supply, and the second cooling circulation device is configured to circulate the second liquid coolant received from the second liquid coolant supply between a second electronic device of the plurality of electronic devices and the heat exchanger, and return it to the second liquid coolant supply.

[0151] 4. A system described in any one of paragraphs 1 to 3, wherein the heat exchanger comprises at least first and second chambers separated by a thermal interface, and the heat exchanger is configured such that the first liquid coolant flows through the at least first chamber and the second liquid coolant flows through the at least second chamber such that heat is transferred from the first liquid coolant to the second liquid coolant through the thermal interface.

[0152] 5. The system of any one of paragraphs 1 to 4, wherein the heat exchanger is disposed within the housing of the electronic module.

[0153] 6. The system of any one of paragraphs 1 to 5, wherein the housing of the electronic module contains a first liquid coolant and the first electronic device is at least partially immersed in the first liquid coolant.

[0154] 7. The first cooling circulation device further comprises a weir, a base and a retaining wall extending from the base, the base and the retaining wall defining a volume for storing a portion of the first liquid coolant; an inlet through which the first liquid coolant flows into the volume; Item 7. The system of item 6, wherein a sufficient inflow of the first liquid coolant into the volume through the inlet causes the first liquid coolant to overflow the retaining wall and collect with the first liquid coolant stored within the housing of the electronic module and external to the weir.

[0155] 8. The system of claim 7, wherein the inlet further comprises a nozzle device for directing the first liquid coolant into the volume.

[0156] 9. The system of claim 7 or 8, wherein the weir further comprises a protrusion extending from the base and / or a retaining wall within the volume of the weir.

[0157] 10. The system of any one of paragraphs 7 to 9, wherein the dam is coupled to a surface of the first electronic device to act as a heat sink.

[0158] 11. The first cooling circulation device 11. The system of any one of paragraphs 1 to 10, further comprising a pump configured to circulate the first liquid coolant around the first cooling circulation device.

[0159] 12. The system described in paragraph 11, wherein the first cooling circulation device is housed within the housing of the electronic module and further comprises a pump inlet positioned to receive the first liquid coolant that is external to the weir.

[0160] 13. The first cooling circulation device 13. The system of claim 11 or claim 12, further comprising at least first and second pipes arranged to transport the first liquid coolant from the pump to the heat exchanger and from the heat exchanger to the inlet of the weir, respectively.

[0161] 14. The system of any one of paragraphs 1 to 13, wherein the second cooling circulation device further comprises a cooling module configured to thermally couple the second electronic device to the second liquid coolant.

[0162] 15. The cooling module comprises a cold plate, the cold plate comprising: a cold plate housing, the cold plate housing having a surface positioned to provide a thermal interface for cooling a second electronic device thermally coupled to the cold plate housing; Item 15. The system of item 14, comprising: at least one channel within the cold plate housing and proximate to a surface of the cold plate housing, the at least one channel being arranged such that a second liquid coolant flows through the at least one channel such that heat received through the surface of the cold plate housing from a second electronic device is transferred to the second liquid coolant.

[0163] 16. The system of paragraph 15, wherein the second cooling circulation device further comprises a plurality of conduits arranged to transport a second liquid coolant between the cold plate, the heat exchanger, and the cooling system.

[0164] 17. A method for cooling a plurality of electronic devices contained within a housing of an electronic module, the method comprising: circulating a first liquid coolant through a first cooling circulation apparatus, the first liquid coolant being circulated between a first electronic device of the plurality of electronic devices and a heat exchanger, the first electronic device being thermally coupled to the first liquid coolant such that heat is transferred from the first electronic device to the first liquid coolant; and circulating a second liquid coolant through a second cooling circulation apparatus, the second liquid coolant being circulated between a second electronic device of the plurality of electronic devices and a heat exchanger, the second electronic device being thermally coupled to the second liquid coolant such that heat is transferred from the second electronic device to the second liquid coolant; A method wherein the first cooling circulation device and the second cooling circulation device are thermally coupled via at least a heat exchanger such that heat is transferred from the first liquid coolant to the second liquid coolant via the heat exchanger.

[0165] 18. The method of claim 17, wherein the second cooling circulation device further comprises a cooling system, and circulating the second liquid coolant around the second cooling circulation device includes circulating the second liquid coolant between a second electronic device of the plurality of electronic devices, a heat exchanger, and the cooling system, and heat is removed from the second liquid coolant by the cooling system.

[0166] 19. The method of clause 17, wherein the second cooling circulation device further comprises a second liquid coolant supply, and circulating the second liquid coolant around the second cooling circulation device includes receiving the second liquid coolant from the second liquid coolant supply, circulating the second liquid coolant between a second electronic device of the plurality of electronic devices and the heat exchanger, and returning the second liquid coolant to the second liquid coolant supply.

[0167] 20. The method of any one of clauses 17 to 19, wherein the heat exchanger comprises at least first and second chambers separated by a thermal interface, and the heat exchanger is configured for flow of a first liquid coolant through at least the first chamber and a second liquid coolant through at least the second chamber, such that heat is transferred from the first liquid coolant to the second liquid coolant through the thermal interface.

[0168] 21. The method of any one of paragraphs 17 to 20, wherein the heat exchanger is disposed within the housing of the electronic module.

[0169] 22. The method of any one of paragraphs 17 to 21, wherein the housing of the electronic module contains a first liquid coolant, and the first electronic device is at least partially immersed in the first liquid coolant.

[0170] 23. The first cooling circuit further comprises a weir, a base and a retaining wall extending from the base, the base and the retaining wall defining a volume for storing a portion of the first liquid coolant; an inlet through which the first liquid coolant flows into the volume; 23. The method of any one of clauses 17-22, wherein sufficient flow of the first liquid coolant into the volume through the inlet causes the first liquid coolant to overflow the retaining wall and collect with the first liquid coolant stored within the housing of the electronic module and external to the weir.

[0171] 24. The method of any one of clauses 17 to 23, wherein the second cooling circulation apparatus further comprises a cooling module configured to thermally couple the second electronic device to the second liquid coolant.

[0172] 25. The cooling module includes a cold plate, the cold plate comprising: a cold plate housing, the cold plate housing having a surface positioned to provide a thermal interface for cooling a second electronic device thermally coupled to the cold plate housing; 25. The method of any one of clauses 17 to 24, comprising: at least one channel within the cold plate housing and proximate to a surface of the cold plate housing, the at least one channel being arranged such that a second liquid coolant flows through the at least one channel such that heat received through the surface of the cold plate housing from a second electronic device is transferred to the second liquid coolant.

[0173] The present disclosure can be practiced in many ways and preferred embodiments will now be described, by way of example only, with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0174] [Figure 1A] 1 is a schematic diagram of a first example implementation of a system for cooling multiple electronic devices contained within a chassis or housing of an electronic module. [Figure 1B] 1 is a schematic diagram of a first example implementation of a system for cooling multiple electronic devices contained within a chassis or housing of an electronic module. [Figure 2A] 1 is a schematic diagram of a second example implementation of a system for cooling multiple electronic devices contained within a chassis or housing of an electronic module. [Figure 2B] 1 is a schematic diagram of a second example implementation of a system for cooling multiple electronic devices contained within a chassis or housing of an electronic module. [Figure 3A] FIG. 10 is a schematic diagram of a third example implementation of a system for cooling multiple electronic devices contained within a chassis or housing of an electronic module. [Figure 3B] FIG. 10 is a schematic diagram of a third example implementation of a system for cooling multiple electronic devices contained within a chassis or housing of an electronic module. [Figure 4A] FIG. 2 is a plan view of an electronic module, which is a specific implementation of the first example of the system according to FIGS. 1A and 1B. [Figure 4B] FIG. 2 is a perspective view of an electronic module, which is a specific implementation of the first example of the system according to FIGS. 1A and 1B. [Figure 4C] FIG. 2 is a perspective view of an electronic module, which is a specific implementation of the first example of the system according to FIGS. 1A and 1B. [Figure 5A] FIG. 4D is a schematic diagram of a system according to an implementation of the electronic module of FIGS. 4A, 4B, and 4C. [Figure 5B] FIG. 4D is a schematic diagram of a system according to an implementation of the electronic module of FIGS. 4A, 4B, and 4C. [Figure 6A] FIG. 3 is a plan view of an electronic module, which is a specific implementation of the second example of the system according to FIGS. 2A and 2B. [Figure 6B] FIG. 3B is a perspective view of a plan view of an electronic module, which is a specific implementation of the second example of the system according to FIGS. 2A and 2B. [Figure 6C] FIG. 3B is a perspective view of a plan view of an electronic module, which is a specific implementation of the second example of the system according to FIGS. 2A and 2B. [Figure 7A] FIG. 6D is a schematic diagram of a system according to an implementation of the electronic module of FIGS. 6A, 6B, and 6C. [Figure 7B] FIG. 6D is a schematic diagram of a system according to an implementation of the electronic module of FIGS. 6A, 6B, and 6C. [Figure 8A] FIG. 4B is a plan view of an electronic module, which is a specific implementation of the third example of the system according to FIGS. 3A and 3B. [Figure 8B] FIG. 4 is a perspective view of an electronic module, which is a specific implementation of the third example of the system according to FIGS. 3A and 3B. [Figure 8C] FIG. 4 is a perspective view of an electronic module, which is a specific implementation of the third example of the system according to FIGS. 3A and 3B. [Figure 9A] FIG. 8D is a schematic diagram of a system according to an implementation of the electronic module of FIGS. 8A, 8B, and 8C. [Figure 9B] FIG. 8D is a schematic diagram of a system according to an implementation of the electronic module of FIGS. 8A, 8B, and 8C. [Figure 10A] FIG. 10 is a perspective view of a cold plate used as a cooling module in the second cooling circulation device. [Figure 10B] FIG. 10 is a cross-sectional view of a cold plate used as a cooling module in the second cooling circulation device. [Figure 10C] FIG. 10 is a cross-sectional view of a cold plate used as a cooling module in the second cooling circulation device. [Figure 11A] FIG. 1 is a perspective view of a weir heat sink used in the first cooling circuit. [Figure 11B] FIG. 1 is an exploded view of a weir heat sink used in the first cooling circuit. [Figure 11C] FIG. 1 is a cross-sectional view of a weir heat sink used in the first cooling circuit. [Figure 12] FIG. 10 is a plan view of a weir heat sink showing fluid flow from the nozzles. [Figure 13A] 10 shows an alternative arrangement of nozzles for a weir heat sink. [Figure 13B] 10 shows an alternative arrangement of nozzles for a weir heat sink. [Figure 14] 1 illustrates a preferred liquid level of a first liquid coolant within the chassis or housing of an electronic module. [Figure 15A] FIG. 1 is a schematic diagram of a plurality of electronic modules connected to a first example of a rack-level cooling system for cooling a second liquid coolant. [Figure 15B] FIG. 10 is a schematic diagram of a plurality of electronic modules connected to a second example of a rack-level cooling system for cooling a second liquid coolant. [Figure 16] 1 is a schematic diagram of the paths for the flow of first and second liquid coolants through a heat exchanger having a total of six inlet and outlet ports. FIG. [Figure 17] 1 shows a heat exchanger with a total of six inlet and outlet ports and with parallel flow between the thermally conductive mating surfaces used for the heat exchanger. [Figure 18] 1 shows a heat exchanger with a total of six inlet and outlet ports and serial flow through the thermally conductive interface used for the heat exchanger. [Figure 19A] FIG. 10 is a schematic diagram of a fourth example implementation of a system for cooling multiple electronic devices contained within a chassis or housing of an electronic module. [Figure 19B] FIG. 10 is a schematic diagram of a fourth example implementation of a system for cooling multiple electronic devices contained within a chassis or housing of an electronic module. [Figure 20A] FIG. 19C is a plan view of an electronic module, which is a specific implementation of the fourth example of the system according to FIGS. 19A and 19B. [Figure 20B] FIG. 19C is a perspective view of an electronic module, which is a specific implementation of the fourth example of the system according to FIGS. 19A and 19B. [Figure 20C] FIG. 19C is a perspective view of an electronic module, which is a specific implementation of the fourth example of the system according to FIGS. 19A and 19B. [Figure 21] FIG. 26 is a detailed view of a port on a heat exchanger in a system according to an implementation of the electronic module in FIGS. 20A, 20B, and 20C. [Figure 22A] 20A, 20B, and 20C are schematic diagrams of systems according to implementations of the electronic modules in FIGS. 20A, 20B, and 20C. [Figure 22B]20A, 20B, and 20C are schematic diagrams of systems according to implementations of the electronic modules in FIGS. 20A, 20B, and 20C. [Figure 23] 1(a)-(c) show schematic diagrams of a single chamber of a heat exchanger having at least two inlets and / or outlets and two paths through a given chamber. DETAILED DESCRIPTION OF THE INVENTION

[0175] In the drawings, like parts are designated by like reference numerals. The drawings are not drawn to scale.

[0176] An electronic module suitable for placement within a server rack is described. The electronic module may have a sealable housing or chassis with a base, a lid, and sidewalls. The electronic module houses multiple electronic devices (computer hardware devices) that generate heat under normal operation. The electronic devices may be directly coupled to the electronic module housing or chassis or may be connected to one or more printed circuit boards (PCBs). The electronic devices and / or PCBs are then connected or mounted within the electronic module housing or chassis. Electrical connections are made to the electronic devices for power or data transfer. The electrical connections may pass through sealable ports in a wall (usually the rear) of the electronic module housing. As well as mechanical fasteners on the exterior of the housing or chassis, the connections may connect to cooperating fasteners and connectors in the server rack.

[0177] This specification is directed to a cooling system for removing heat generated by electronic devices housed within an electronic module during operation. Because electronic modules are typically sealed or encapsulated during use, generated heat may be contained within the housing or chassis of the electronic module, making efficient heat transfer into and out of the electronic module particularly important. Examples of electronic modules with hybrid cooling systems including two cooperating circulation loops of liquid coolant are described below. Figures 1A and 1B, 2A and 2B, 3A and 3B, and 17A and 17B, respectively, show alternative configurations of two cooperating circulation loops within an electronic module.

[0178] A first example of a system is shown in Figures 1A and 1B. In both Figures 1A and 1B, the configuration of components within the electronic module is the same; Figures 1A and 1B differ only by the external system of the electronic module, as discussed below.

[0179] In the example of Figures 1A and 1B, electronic module 10 includes a first electronic device 12, a first cooling module 14 and a second cooling module 16 (not shown in Figures 1A and 1B but coupled to respective second and third electronic devices), and a heat exchanger 18.

[0180] The first cooling circuit 20 is completely enclosed within the housing or chassis of the electronic module 10. When the system is in use, the first cooling circuit 20 provides a first liquid cooling The coolant is circulated (or transported) from the heat exchanger 18 to the first electronic device 12 and then from the first electronic device back to the heat exchanger 18. The first cooling circulation system 20 is a closed loop (in other words, the coolant is circulated forever and is not replaced or removed within the loop).

[0181] During use, the second cooling circulation device 22 receives a second liquid coolant at a first inlet to the electronic module 10. The second liquid coolant is then transported to the first cooling module 14 and the second cooling module 16 (coupled to second and third electronic devices, respectively). The second liquid coolant passes through the first cooling module 14 and the second cooling module 16 and then proceeds toward the heat exchanger 18 (more specifically, the thermally conductive mating surfaces for heat transfer in the heat exchanger). Finally, after passing through the heat exchanger 18 (across the thermally conductive mating surfaces for heat transfer in the heat exchanger), the second liquid coolant exits the electronic module 10.

[0182] 1A and 1B, the second liquid coolant is routed outside the electronics module 10 between the cooling modules and the heat exchanger. In particular, after passing through the cooling modules 14, 16, the second liquid coolant passes through a first outlet in the wall of the electronics module's housing. The second liquid coolant then passes through a bulkhead connector and then re-enters the electronics module 10 at a second inlet in the wall of the electronics module's housing. After passing through the second inlet, the second liquid coolant enters the heat exchanger 18 directly. Nevertheless, in other examples, the second liquid coolant may be routed directly from the first cooling module 14 and the second cooling module 16 to the heat exchanger 18 without exiting and re-entering the electronics module 10.

[0183] The first electronic device 12 is thermally coupled to the first liquid coolant such that heat generated by the first electronic device 12 is transferred to the first liquid coolant when the system is in use. The second and third electronic devices are thermally coupled to the second liquid coolant through surfaces of the first and second cooling modules 14 and 16. For example, the first and second cooling modules 14 and 16 may be physically coupled to the second and third electronic devices, respectively, or may optionally be thermally coupled with an intermediate layer therebetween. When the system is in use, heat generated by the second and third electronic devices is transferred to the second liquid coolant.

[0184] The heat exchanger 18 typically includes at least a first and a second chamber with a thermally conductive interface therebetween. A first liquid coolant passes through the first chamber, and a second liquid coolant passes through the second chamber. Heat can be transferred from the hotter liquid coolant to the colder liquid coolant via the thermal interface. The two liquid coolants do not mix. During normal operation, the first liquid coolant is at a higher temperature than the second liquid coolant. Thus, when the system is in use, heat is transferred from the first liquid coolant to the second liquid coolant. By this means, the first liquid coolant is cooled, and heat from the first electronic device is ultimately transferred to the second liquid coolant and transported out of the electronic module.

[0185] 1A and 1B, the electronic modules 10 are each connected to a cooling system external to the electronic modules to provide and / or cool a second liquid coolant. In both examples, connectors 24, 26 of the rack 30 (which may house multiple electronic modules) connect the second cooling circuit 22 of the electronic modules to the external cooling system. It will be understood that the same external cooling system may be connected to multiple electronic modules housed within the rack 30, and that multiple electronic modules may be connected to the external cooling system in either series or parallel.

[0186] In the example of FIG. 1A, a cooling system including a pump 32 and a heat exchanger 34 is located between the connectors 24, 26 and the exterior of the rack 30. The pump 32 is used to circulate a second liquid coolant, causing the second liquid coolant to flow through a second cooling circuit of the electronic module 10. The heat exchanger is used to transfer heat from the second liquid coolant to an additional coolant medium 36 (which may be a third liquid coolant). In one example, the additional coolant medium may be a facility-level supply of chilled water. Alternatively, the heat exchanger may be a liquid-to-air heat exchanger in which heat from the second liquid coolant is transferred to a moving air source. In either case, the second liquid coolant is circulated in a closed loop, and heat is removed from the second liquid coolant and transferred away from the electronic module 10.

[0187] 1B, the second liquid coolant is provided from a facility-level supply (such as a chilled water source) that is connected to an inlet 38 and an outlet 40 of the rack 30. The second liquid coolant circulates in an open loop, passing through the electronic modules 10 and subsequently being replaced by a fresh supply of the second liquid coolant.

[0188] The electronic module of FIGS. 2A and 2B shares common features with the example of FIGS. 1A and 1B. In particular, the electronic module 10 of FIGS. 2A and 2B also includes a first electronic device 12, a first cooling module 14 and a second cooling module 16 (coupled to respective second and third electronic devices, not shown), and a heat exchanger 18. The configuration of the first cooling circuit 20 in the example of FIGS. 2A and 2B is substantially the same as that described above with respect to FIGS. 1A and 1B. However, the configuration of the second cooling circuit 22 is different. In particular, in the example of FIGS. 2A and 2B, the second cooling circuit passes the second liquid coolant through the heat exchanger 18 before passing through the cooling modules 14, 16 (in the example of FIGS. 1A and 1B, the second cooling circuit passes the second liquid coolant through the cooling modules 14, 16 before passing through the heat exchanger 18).

[0189] 2A and 2B, when the system is in use, the second liquid coolant enters the electronic module 10 through a first inlet into the housing or chassis of the electronic module. After passing through the first inlet, the second liquid coolant is received directly at the heat exchanger 18. The second liquid coolant passes through the heat exchanger 18 (specifically, through thermally conductive mating surfaces for heat transfer in the heat exchanger) and proceeds toward the cooling modules 14, 16.

[0190] 2A and 2B, after passing through the heat exchanger, the second liquid coolant passes directly through a first outlet of the electronics module. The second liquid coolant then re-enters the electronics module through a second inlet via a bulkhead connector. From there, the second liquid coolant is routed to a first cooling module 14 and a second cooling module 16 (coupled to second and third electronic devices, respectively). While in this example the second liquid coolant is routed out of the electronics module between the heat exchanger and the cooling modules and returned to the electronics module, it will be understood that the system can be configured such that the second liquid coolant is routed directly from the heat exchanger 18 to the cooling modules 14, 16 without exiting and re-entering the electronics module 10.

[0191] Returning to the example of Figures 2A and 2B, after passing through the first cooling module 14 and the second cooling module 16, the second liquid coolant is directed from the chassis or housing out of the electronic module 10 through a second outlet.

[0192] Considering the arrangements of FIGS. 2A and 2B, heat from the first liquid coolant is transferred to the second liquid coolant before it passes through the cooling modules 14, 16 (and thus before it receives heat generated by the second and third electronic devices). 1A and 1B, the temperature of the second liquid coolant is lower in the heat exchanger than the temperature of the second liquid coolant in the heat exchanger. Thus, the cooling performance of the second liquid coolant that cools the first liquid coolant in the heat exchanger is higher in the example of FIGS. 2A and 2B compared to the example of FIGS. 1A and 1B. However, this may come at the expense of the cooling power in the cooling modules 14, 16, which is greater in the example of FIGS. 1A and 1B.

[0193] The electronic module 10 according to Figure 2A is connected to an external cooling system via a rack 30 identical to the external cooling system described above with respect to Figure 1A (i.e., heat transfer from the second liquid coolant to a third coolant medium via a further heat exchanger). The electronic module 10 according to Figure 2B is connected to an external cooling system via a rack 30 identical to the external cooling system described above with respect to Figure 1B (i.e., a supply of the second liquid coolant from a facility-level supply such as a chilled water supply).

[0194] The electronic module of Figures 3A and 3B shares common features with the examples of Figures 1A and 1B and Figures 2A and 2B. In particular, the electronic module 10 of Figures 3A and 3B also includes a first electronic device 12, a first cooling module 14 and a second cooling module 16 (coupled to respective second and third electronic devices, not shown), and a heat exchanger 18. The configuration of the first cooling circuit 20 in the example of Figures 3A and 3B is substantially the same as the configuration described above with respect to Figures 1A and 1B and Figures 2A and 2B. However, the configuration of the second cooling circuit 22 is different compared to each of the above-mentioned examples. In particular, in the example of Figures 3A and 3B, the heat exchanger 18 is arranged in parallel with the cooling modules 14, 16 within the second cooling circuit.

[0195] In the second cooling circuit 22 of the electronic module 10 shown in Figures 3A and 3B, when the system is in use, the second liquid coolant enters the electronic module through a first inlet on the electronic module housing and splits into two parallel branches. The first branch passes through the heat exchanger 18 (specifically, across thermally conductive interfaces for heat transfer in the heat exchanger) and then rejoins the second branch, which is directed from the electronic module housing to an outlet. The second branch is sent directly to the first cooling module 14 and the second cooling module 16 (coupled to second and third electronic devices, respectively). After passing through the cooling modules 14 and 16, the second branch rejoins the first branch, and the second liquid coolant is directed out of the electronic module.

[0196] 3A and 3B, the second liquid coolant receives heat from the second and third electronic devices (through the cooling module) in separate portions from the first liquid coolant in the heat exchanger (through the thermally conductive interface). The flow of the second liquid coolant through each branch can be carefully controlled to balance the cooling performance of the cooling module compared to the heat exchanger.

[0197] The electronic module 10 according to Figure 3A is connected to an external cooling system via the same rack 30 as the external cooling system described above with respect to Figure 1A. The electronic module according to Figure 3B is connected to an external cooling system via the same rack 30 as the external cooling system described above with respect to Figure 1B.

[0198] 1A-3B, and in the example of FIGS. 17A and 17B below, the first cooling circulation system 20 may provide immersion cooling. In other words, the first liquid coolant may be stored within the housing or chassis of the electronic module 10, so that the first electronic device 12 (and possibly other electronic devices) is at least partially immersed in the first liquid coolant when the system is in use. By at least partially immersing a portion of the electronic device 12 (e.g., 12), the electronic device is in direct contact with the first liquid coolant, which allows heat to be transferred directly from the electronic device 12 to the first liquid coolant. When the first cooling circulation apparatus 20 provides immersion cooling in this manner, the first liquid coolant is still circulated to flow around the housing or chassis and through the heat exchanger 18 so that heat can be transferred from the first liquid coolant to the second liquid coolant via the heat exchanger.

[0199] In an advantageous embodiment, the first cooling circulation device 20 can provide immersion cooling as described above. In this case, the first cooling circulation device 20 includes a volume of a first liquid coolant stored within the housing or chassis of the first electronic module 10. The first liquid coolant is a dielectric. A reservoir of the first liquid coolant is stored within the housing or chassis, and a portion of the first liquid coolant is pumped to and from the reservoir around the housing or chassis, causing flow through the first electronic device 12. In this manner, heat is transferred from the first electronic device 12 to the first liquid coolant. The flow of the first liquid coolant can be enabled by receiving the first liquid coolant through a pump inlet and a pump housed within the electronic module 10 and then pumping the first liquid coolant to another region of the housing of the electronic module 10. In one example, the first liquid coolant is pumped to flow over the first electronic device 12. In yet another example, as discussed in more detail below, a weir heat sink may be implemented coupled to the first electronic device 12. If immersion cooling is used, the first electronic device 12 (and others of the plurality of electronic devices) may be partially immersed or fully immersed (submerged) in the first liquid coolant.

[0200] In a particular example, the relative placement of the first electronic device 12 within the electronic module housing relative to the first and second cooling modules, and the liquid level of the first liquid coolant, are configured so that the first liquid coolant does not come into direct contact with the first cooling module 14 and the second cooling module 16. In particular, the cooling modules 14, 16 are positioned above the highest liquid level of the first liquid coolant when the system is operating. As a result of this configuration, the first liquid coolant and the cooling modules 14, 16 are not directly thermally coupled, and heat is not transferred directly from the first liquid coolant to the cooling modules 14, 16 (or vice versa). The inventors have recognized that by spatially separating the cooling modules 14, 16 from the first liquid coolant, more efficient cooling of the entire electronic module 10 can be achieved. In this way, the majority of the heat transfer from the first liquid coolant to the second liquid coolant takes place in the heat exchanger 18, which is a separate and specific component that can be configured to provide optimal conditions for heat transfer between the two cooling liquids.

[0201] As will be understood by those skilled in the art, each of the examples described above with reference to Figures 1A and 1B, 2A and 2B, and 3A and 3B, and described below with reference to Figures 17A and 17B, describes a first cooling circuit 20 and a second cooling circuit 20 in which heat is transferred from a first electronic device 12 to a first liquid coolant, from at least a second electronic device to a second liquid coolant, and then from the first liquid coolant to the second liquid coolant via a heat exchanger 18. However, in each of the examples of Figures 1A and 1B, 2A and 2B, 3A and 3B, and 17A and 17B, the arrangement of the second cooling circuit 20 is different. More specifically, in Figures 1A and 1B, the cooling modules 14, 16 are arranged in series with the heat exchanger 18, with the cooling modules 14, 16 before the heat exchanger 18 in the direction of flow of the second liquid coolant. 2A and 2B, the cooling modules 14, 16 are arranged in series with the heat exchanger 18, with the heat exchanger 18 preceding the cooling modules 14, 16 in the direction of flow of the second liquid coolant. In FIGS. 3A and 3B, the cooling modules 14, 16 are arranged in parallel with the heat exchanger 18. In FIGS. 3A and 3B, the cooling modules 14, 16 are specifically arranged in parallel with the thermally conductive mating surfaces within the heat exchanger 18.

[0202] Each of the above-described configurations has advantages. In the configuration of Figures 1A and 1B, the second liquid coolant provides the greatest cooling power to the electronic devices coupled to the cooling modules 14, 16. Typically, these electronic devices are selected to be the devices that generate the most heat within the electronic module 10. Because the second liquid coolant is at its lowest temperature at its point of entry into the electronic module 10 as a result of the second liquid coolant passing through the cooling modules 14, 16 before the heat exchanger 18, the largest possible thermal gradient is provided between the cooling modules 14, 16 and the coupled electronic devices. Therefore, the efficiency of heat transfer from the electronic devices coupled to the cooling modules 14, 16 is higher in the configuration of Figures 1A and 1B than in Figures 2A and 2B.

[0203] 1A and 1B, the temperature of the second liquid coolant is relatively higher as it passes through heat exchanger 18 compared to the configurations of Figures 2A and 2B. Accordingly, the thermal gradient between the first and second liquid coolants in heat exchanger 18 is relatively less steep in the configurations of Figures 1A and 1B compared to the configurations of Figures 2A and 2B. Accordingly, the configurations of Figures 1A and 1B may provide less efficient cooling for the first liquid coolant compared to the configurations of Figures 2A and 2B.

[0204] Indeed, the inventors have recognized that the configurations of Figures 1A and 1B may be particularly useful for targeting particularly high heat generating electronic devices, while the configurations of Figures 2A and 2B provide a relatively large overall cooling capacity for the electronic module 10. The configurations of Figures 2A and 2B may provide less efficient heating for a particular electronic device coupled to the cooling modules 14, 16, but may provide more efficient cooling for the first liquid coolant, thereby removing a greater amount of heat overall from the electronic module 10. It is possible to envision that either the configurations of Figures 1A and 1B or the configurations of Figures 2A and 2A may be advantageous in different scenarios.

[0205] 3A and 3B provide the additional possibility of arranging the cooling modules 14, 16 and heat exchangers in parallel within the second cooling circuit. This arrangement provides the maximum possible temperature difference between both the first and second liquid coolants in the heat exchanger 18, and between the second liquid coolant and the cooling modules 14, 16 and the associated electronics module. This arrangement also allows for better control of the flow of the second liquid coolant through the cooling modules 14, 16 and the heat exchanger 18, allowing different ratios of flow through each element. This allows for balancing the cooling performance of the cooling modules 14, 16 and the heat exchanger 18. This configuration may be ideal for systems containing multiple high-temperature auxiliary components on a PCB board, which are typically cooled by the first cooling circuit.

[0206] The configuration of Figures 17A and 17B, described below, provides an alternative configuration in which the thermally conductive interfaces of the cooling modules 14, 16 and the heat exchanger are arranged in parallel in the second cooling circuit. In other words, the cooling modules are arranged on parallel branches of the second cooling circuit, compared to the portion of the heat exchanger where heat is transferred from the first cooling liquid (in the first chamber) to the second liquid coolant (in the second chamber). This arrangement allows for efficient cooling of both the cooling modules and the first liquid coolant by providing each element with the second liquid coolant at the lowest possible temperature. Adjusting the relative flow rates between each branch of the second cooling circuit allows for balancing the cooling power between the cooling modules and the first liquid coolant by changing the ratio of the second liquid coolant flowing through each branch. Compared to the parallel configuration of Figures 3A and 3B, the novel arrangement of the heat exchangers discussed for use in the systems of Figures 17A and 17B also offers many other advantages. In particular, the amount of piping and number of connections in the second cooling circulation system is reduced because the second liquid coolant is injected and evacuated directly into and out of the heat exchanger, thereby reducing the number of components and potential leak points in the system. This not only improves space efficiency but also the volume within the housing of the electronic module.

[0207] 1A-3B and 17A-17B, the first and second cooling modules 14, 16 are arranged in parallel with each other within the second cooling circuit 22; however, the first and second cooling modules 14, 16 may alternatively be arranged in series. While two cooling modules are shown, one cooling module or any number of cooling modules 14, 16 may be incorporated into the second cooling circuit 22 arranged in parallel, in series, or in a combination of parallel and series configurations. Furthermore, while the first cooling circuit may be configured to provide immersion cooling (as described above), it will be understood that the first cooling circuit may be configured using a closed loop in which a cold plate (or the like) is coupled to at least the first electronic device to provide cooling other than immersion. In this case, the configuration of the first cooling circuit relative to the second cooling circuit would not be changed compared to the previously described examples.

[0208] Further specific implementations of each of the system examples discussed above (with different configurations for the second cooling circulation device) are described below.

[0209] a second cooling circulation system including a cold plate and a heat exchanger in series, wherein a second liquid coolant passes through the cold plate before passing through the heat exchanger; Referring to Figure 4A, a specific implementation of the example electronic module 100 described above with reference to Figures 1A and 1B (where the cooling module and heat exchanger are arranged in series, with the cooling module positioned before the heat exchanger in the direction of fluid flow) is depicted. The electronic module 100 may be a module or a server blade, with appropriate dimensions and external connectors to fit within a typical server rack (not shown). The same electronic module 100 is shown in Figures 4B and 4C, each depicting a different perspective view of the module.

[0210] The electronic module 100 has an outer housing or enclosure 110, which may have a base, walls, and a lid, and may be hermetically sealed. Multiple electronic devices (or heat-generating components) are mounted within the housing. In some cases, the components may be mounted on a printed circuit board (PCB) 120, which may be connected to the base, lid, or walls of the housing. The described system is intended to remove heat generated by the electronic devices from within the electronic module.

[0211] The first cooling circuit (or first cooling loop) is used to cool a specific electronic device among multiple electronic devices mounted in the electronic module, and the second cooling circuit (or second cooling loop) is used to cool other heat-generating components. For example, the second cooling circuit may have a greater cooling power and thus be used to cool a specific component that generates a greater amount of heat than the component cooled by the first cooling circuit.

[0212] In the example depicted in Figures 4A, 4B, and 4C, the electronics module has a first cooling circuit (or first cooling loop) that provides immersion cooling. The first cooling circuit is contained entirely within the housing 110 of the electronics module. In particular, a first liquid coolant (such as a dielectric liquid) is contained within the sealable housing of the electronics module such that several components to be cooled are at least partially immersed in the first liquid coolant. The volume of the first liquid coolant contained within the cavity of the housing of the electronics module can be considered a reservoir of the first liquid coolant.

[0213] The first liquid coolant from the reservoir of first liquid coolant is collected or received at pump inlet 190. Pump inlet 190 may be shaped to improve the flow of liquid coolant towards pump 185. Pump 185 may be configured to pump the first cooling circulation system (or the second cooling circulation system). The pump 185 moves a first liquid coolant through the heat exchanger 170 (the first cooling loop). After passing through the pump 185, the first liquid coolant is moved through a pipe 195 into the heat exchanger 170 (more specifically, across thermally conductive interfaces within the heat exchanger) where it is cooled. In particular, heat retained in the first cooling fluid may be transferred to a second cooling fluid that has also passed through the heat exchanger, as described below. As will be appreciated, the first liquid coolant entering the heat exchanger is at a higher temperature than the first liquid coolant exiting the heat exchanger.

[0214] In the examples of FIGS. 4A, 4B, and 4C, a pipe 200 is connected to the heat exchanger 170 to carry the first cooling fluid. The distal end of the pipe 200 has one or more outlets or nozzles 205a, 205b. In the examples of FIGS. 4A, 4B, and 4C, the outlet or nozzle 205a forms an inlet to weirs 202a, 202b, respectively. The weirs act as heat sinks and are part of the first cooling circulation system. Weirs are described in more detail below with respect to FIGS. 12A-14B. However, the first cooling circulation system can be configured without the weir heat sinks described above. For example, the nozzles can be positioned to distribute the first liquid coolant exiting the heat exchanger near the first electronic device, or to direct the first liquid coolant through a reservoir of first liquid coolant within the housing or chassis (in which the first electronic device is at least partially immersed) toward a pump inlet.

[0215] The first cooling fluid exits outlets or nozzles 205a, 205b and passes through weirs 202a, 202b (if used) until it collects in a reservoir of first liquid coolant contained within the volume of housing 110 of electronic module 100. In this manner, the cooler first cooling fluid that has passed through the heat exchanger can be reintroduced into the first cooling fluid tank or reservoir within housing 110 to cool any electronic components partially immersed in the reservoir. Specifically, the cooled first liquid coolant will absorb heat from surfaces of electronic devices (including the first electronic device with which it is in contact). Eventually, the first liquid coolant is recollected at the pump inlet, thereby completing its flow through the first cooling circuit (or first cooling loop).

[0216] 4A, 4B, and 4C also depict a second cooling circulation apparatus. The second cooling circulation apparatus incorporates one or more cold plates 125a, 125b, each mounted to one or more electronic devices (not visible in FIG. 4A). Ideally, the electronic devices require higher-performance cooling. The cold plates 125a, 125b are modules or chambers through which a second cooling fluid (such as water) can be passed. Heat can be transferred from the electronic device to the second cooling fluid within the cold plates by thermal conduction through the mounting surface of the cold plate coupled to the given electronic device. The cold plates 125a, 125b of the second cooling circulation apparatus are discussed in more detail below with respect to FIGS. 10A, 10B, and 10C.

[0217] The second cooling circulation device of FIGS. 4A, 4B, and 4C has two cold plates connected in parallel. In particular, a single inlet conduit 135 is connected to a first inlet 145 in the wall of the housing to receive the second cooling fluid to be injected into the electronics module. The first inlet 145 includes a connector, which may be any suitable type of connector, including a quick-disconnect connector. At its distal end, the single inlet conduit 135 is connected to an inlet manifold 150 to which two additional inlet conduits 140a, 140b are connected. The additional inlet conduits 140a, 140b are each connected to a respective cold plate 125a, 125b. In this manner, the second cooling fluid can be transported in parallel to each of the cold plates 125a, 125b within the electronics module. The second liquid coolant then passes through the cold plates, as discussed below with respect to FIGS. 10A, 10B, and 10C.

[0218] An exhaust conduit 155a, 155b is connected to each of the respective cold plates 125a, 125b. The exhaust conduits 155 a, 155 b are connected to an exhaust manifold 160 to which a single exhaust conduit 165 is also connected for transporting the second liquid coolant out of the exhaust manifold 160.

[0219] A single exhaust conduit 165 connects to a first outlet 250 in the wall of the housing, which directs the second liquid coolant out of the housing through a connector (such as bulkhead connector 222). From the first outlet 250, the second liquid coolant passes through the bulkhead connector 222 and to a second inlet 223 in the wall of the housing. From there, the second liquid coolant is routed directly to the inlet of the heat exchanger 170, where it flows across thermally conductive mating surfaces therein. The heat exchanger 170 is disposed entirely within the housing 110 of the electronics module. In the particular example of FIGS. 4A, 4B, and 4C, the heat exchanger 170 is a plate heat exchanger and is connected to the wall of the housing 110. However, other suitable types of heat exchangers (as discussed further below) can be used and can be located anywhere within the electronics module (or, less preferably, outside the electronics module).

[0220] The heat exchanger 170 may be of any suitable type that allows heat exchange between a first coolant fluid and a second coolant fluid while maintaining separation (not mixing) of the two liquid coolants. For example, the heat exchanger may have a first chamber through which a first liquid coolant flows, separated from a second chamber through which a second coolant flows. The wall(s) separating the first and second chambers may act as a thermal interface (or thermally conductive interface), through which heat may be transferred. In particular, heat may be transferred from a hotter liquid coolant (which in this example would be the second liquid coolant under normal operation) to a cooler liquid coolant (which in this example would be the first liquid coolant under normal operation) as a result of a temperature gradient across the thermal interface. As envisioned by those skilled in the art, more than two chambers may be included in the heat exchanger, and more than two thermal interfaces may be provided to separate chambers through which different liquid coolants flow. More than two paths through each chamber may be provided. The heat exchanger may include fins or other features on the thermal interface surface to facilitate heat exchange.

[0221] 4A, 4B, and 4C, a second outlet 180 in the wall of the electronics module housing 110 is connected to the outlet of the heat exchanger 170 and is positioned to receive the second liquid coolant passing through the heat exchanger. As will be appreciated, the second liquid coolant exiting the heat exchanger 170 will be at a higher temperature than the second liquid coolant entering the heat exchanger 170 as a result of heat absorption from the first liquid coolant within the heat exchanger 170. The second outlet 180 includes a connector, which may be any suitable type of connector, including a quick disconnect connector.

[0222] 4A, 4B, and 4C, the first inlet 145 and second outlet 180 may each be connected to a cooling system or second liquid coolant supply through the server rack (e.g., by piping attached to or integral with the rack connected to the inlet 145 and outlet 180, as needed). This is discussed in more detail below with respect to FIGS. 5A and 5B.

[0223] As will be appreciated, different devices within an electronic module may generate different amounts of heat than other components, and therefore require different cooling rates. Thus, the described configuration provides a cooling system that delivers effective and efficient cooling to all electronic devices within the electronic module. In particular, the second cooling circuit may provide high-performance cooling for the hottest components, while the first cooling circuit may provide cooling for other components within the electronic module. In the present application, the use of a heat exchanger to exchange heat between the first and second cooling circuits improves the overall efficiency of the cooling. In contrast, in prior art systems, cooling is achieved by transferring a reservoir of first coolant to a low-temperature reservoir cooled by a second coolant. It can be limited by exposure to a hot plate.

[0224] Compared to some other configurations described herein, this described configuration provides higher cooling performance at the cold plate when the second liquid coolant (which may be a facility-grade water-based coolant) is at its lowest temperature because the second liquid coolant is supplied directly to the cold plate before reaching the heat exchanger. However, as explained below, this configuration typically does not provide higher overall cooling performance than the cooling performance of the configurations described below with reference to FIGS. 6A-6C and 8A-8C. Nevertheless, this configuration may be advantageous in systems where the main heat-generating electronic device (such as a main processor or equivalent) is very hot and auxiliary components on PCBs within the electronic module are relatively cool. It can also be used when there is a particular concern about processor performance or maintaining the lowest possible temperature for a particular electronic device within the electronic module.

[0225] 5A and 5B show schematic diagrams of the first and second cooling circulation devices of FIGS. 4A, 4B, and 4C when the electronic module 100 is connected in a rack 400. The arrangement of the first and second cooling circulation devices within the electronic module is the same for both examples of FIGS. 5A and 5B. However, the apparatus for providing the low-temperature second liquid coolant to the electronic module is different in the two examples of FIGS. 5A and 5B. In particular, the external cooling system for providing the second liquid coolant in the example of FIG. 5A is the same as the external cooling system described above with reference to FIG. 1A (i.e., heat transfer from the second liquid coolant to a third coolant medium via an additional heat exchanger). The external cooling system for providing the second liquid coolant in the example of FIG. 5B is the same as the external cooling system described above with reference to FIG. 1B (i.e., a supply of second liquid coolant from a facility-level supply, such as a chilled water supply).

[0226] 5A and 5B, a first cooling circulation system is shown having a pump inlet 190, a pump 185, a heat exchanger 170, and a weir 202 for circulating a first liquid coolant within the housing of the electronic module 100. Figures 5A and 5B further show a second cooling circulation apparatus comprising first and second cooling modules (or cold plates), and a heat exchanger.

[0227] During use, the second liquid coolant is received into the electronic module 100 through the first inlet 145 and provides coolant through conduits to two cooling modules (or cold plates) 125a, 125b arranged in parallel. After passing through the cooling modules (or cold plates) 125a, 125b, the second liquid coolant is transported through various conduits to the first outlet and then through pipes to the second inlet and directly into the heat exchanger 170, where heat is transferred from the first liquid coolant to the second liquid coolant. From the heat exchanger 170, the second liquid coolant is sent out of the electronic module via the second outlet 180. The first inlet 145 and the second outlet 180 can be connected to an inlet manifold 405 or an outlet manifold 410, respectively, in a server rack 400 in which the electronic module 100 is mounted. The first inlet and the second outlet can be connected to the inlet and outlet manifolds of the server rack via quick-disconnect connectors.

[0228] a second cooling circuit including a cold plate and a heat exchanger in series, wherein the second liquid coolant passes through the heat exchanger before passing through the cold plate; Referring to Figure 6A, a specific implementation of the example electronic module 100 described above with reference to Figures 2A and 2B (where the cooling module and heat exchanger are arranged in series, with the heat exchanger positioned before the cooling module in the direction of fluid flow) is depicted. The electronic module may be a module or a server blade, with appropriate dimensions and external connectors to fit within a typical server rack (not shown). The same electronic module 100 is shown in Figures 6B and 6C, each depicting a different perspective view of the module.

[0229] The electronic module has an outer housing or enclosure 110, which may have a base, walls, and a lid, and may be hermetically sealed. Multiple electronic devices (or heat-generating components) are mounted within the housing. In some cases, the components may be mounted on a printed circuit board (PCB) 120, which may be connected to the base, lid, or walls of the housing. The described system is intended to remove heat generated by the electronic devices from within the electronic module.

[0230] The first cooling circuit (or first cooling loop) is used to cool a specific electronic device among multiple electronic devices mounted in the electronic module, and the second cooling circuit (or second cooling loop) is used to cool other heat-generating components. For example, the second cooling circuit may have a greater cooling power and thus be used to cool a specific component that generates a greater amount of heat than the component cooled by the first cooling circuit.

[0231] In the example depicted in Figures 6A, 6B, and 6C, the electronics module has a first cooling circuit (or first cooling loop) that provides immersion cooling. The first cooling circuit is contained entirely within the housing 110 of the electronics module. In particular, the first liquid coolant is contained within the sealable housing of the electronics module such that several components 115 to be cooled are at least partially immersed in the first liquid coolant. The first liquid coolant is contained within the volume of the housing of the electronics module and can be thought of as a reservoir of the first liquid coolant.

[0232] First liquid coolant from a first liquid coolant reservoir is collected or received at pump inlet 190. Pump inlet 190 may be shaped to improve the flow of liquid coolant toward pump 185. Pump 185 moves the first liquid coolant through a first cooling circuit (or first cooling loop). The first liquid coolant passing through pump 185 is moved through pipe 195 into heat exchanger 170 (passing across internal thermally conductive interfaces) where it is cooled. In particular, heat retained in the first cooling fluid may be transferred to a second cooling fluid that has also passed through the heat exchanger, as described below. As will be appreciated, the first liquid coolant entering the heat exchanger is at a higher temperature than the first liquid coolant exiting the heat exchanger.

[0233] In the examples of FIGS. 6A, 6B, and 6C, a pipe 200 is connected to the heat exchanger 170 to carry the first cooling fluid. The distal end of the pipe 200 has one or more outlets or nozzles 205a, 205b. In the particular example of FIGS. 6A, 6B, and 6C, the outlet or nozzle 205a forms an inlet to weirs 202a, 202b, respectively. The weirs act as heat sinks and are part of the first cooling circulation system. Weirs are described in more detail below with respect to FIGS. 12A-14B. However, the first cooling circulation system can be configured without the weir heat sinks described above. For example, the nozzles can be positioned to distribute the first liquid coolant exiting the heat exchanger near the first electronic device, or to direct the first liquid coolant through a reservoir of first liquid coolant within the housing or chassis (in which the first electronic device is at least partially immersed) toward a pump inlet.

[0234] The first cooling fluid exits outlets or nozzles 205a, 205b and passes through weirs 202a, 202b (if used) until it collects in a reservoir of first liquid coolant contained within the volume of housing 110 of electronic module 100. In this manner, the cooler first cooling fluid that has passed through the heat exchanger can be reintroduced into the tank or reservoir of first cooling fluid within housing 110 to cool any electronic components partially immersed in the reservoir. Specifically, the cooled first liquid coolant will absorb heat from the surfaces of electronic devices (including the first electronic device with which it is in contact). Ultimately, the first liquid coolant The coolant is recollected at the pump inlet, thereby completing its flow through the first cooling circuit (or first cooling loop).

[0235] FIGS. 6A, 6B, and 6C also depict a second cooling circulation apparatus. The second cooling circulation apparatus incorporates one or more cold plates 125a, 125b, each mounted to one or more electronic devices 130a, 130b. Ideally, the electronic devices 130a, 130b require higher-performance cooling. The cold plates 125a, 125b are modules or chambers through which a second cooling fluid (such as water) can be passed. Heat can be transferred from the electronic devices 130a, 130b to the second cooling fluid within the cold plates by thermal conduction through the mounting surface of the cold plate coupled to the given electronic device. The cold plates 125a, 125b of the second cooling circulation apparatus are described in more detail below with reference to FIGS. 10A, 10B, and 10C. The second cooling circulation apparatus of FIGS. 6A, 6B, and 6C has two cold plates connected in parallel.

[0236] The second cooling circulation device of Figures 6A, 6B, and 6C is configured with a heat exchanger before the cold plate in the direction of flow of the second liquid coolant. In particular, the second liquid coolant enters the electronics module housing 110 through the first inlet 145 and is routed directly to the heat exchanger 170 (which is entirely contained within the electronics module housing). The second liquid coolant flows across thermally conductive mating surfaces in the heat exchanger, where heat can be transferred to the second liquid coolant to form the first liquid coolant. The heat exchanger 170 may be a plate heat exchanger, as described above, or may be of any suitable type. The first inlet 145 includes a connector, which may be any suitable type of connector, including a quick-connect connector.

[0237] As will be appreciated, the second liquid coolant exiting the heat exchanger 170 will be at a higher temperature than the second liquid coolant entering the heat exchanger 170 as a result of the absorption of heat (through the thermally conductive interface) from the first liquid coolant within the heat exchanger 170. After passing through the heat exchanger 170, the second liquid coolant is directed out of the heat exchanger 170 through a first outlet 250 within the housing of the electronics module. The second liquid coolant is directed to a bulkhead connector 222 and returned into the housing through a second inlet 223.

[0238] The single inlet conduit 135 is connected to a second inlet 223 in the wall of the housing for receiving the second liquid coolant. At its distal end, the single inlet conduit 135 is connected to an inlet manifold 150 to which two additional inlet conduits 140a, 140b are connected. The additional inlet conduits 140a, 140b are each connected to a respective cold plate 125a, 125b. In this manner, the second cooling fluid can be delivered in parallel to each of the cold plates 125a, 125b within the electronic module. The second liquid coolant then passes through the cold plates, as described below with respect to FIGS. 10A, 10B, and 10C.

[0239] An exhaust conduit 155 a, 155 b is connected to each of the respective cold plates 125 a, 125 b. The exhaust conduits 155 a, 155 b receive the second liquid coolant exhausted from each of the cold plates 125 a, 125 b in parallel. The exhaust conduits 155 a, 155 b are connected to an exhaust manifold 160, which is also connected to a single exhaust conduit 165 for transporting the second liquid coolant out of the exhaust manifold 160.

[0240] The single exhaust conduit 165 is connected to a second outlet 180 in the wall of the housing of the electronic module. The second outlet 180 includes a connector, which may be any suitable type of connector, such as a quick disconnect connector.

[0241] Although not shown in FIGS. 6A, 6B, and 6C, the first inlet 145 and the second outlet 18 0 may each be connected to a cooling system or second liquid coolant supply (e.g., via a rack having connectors for connecting to inlet 145 and outlet 180, as needed). This is described in more detail below with respect to Figures 7A and 7B.

[0242] In this configuration, because the second liquid coolant passes through the heat exchanger before the cold plate, the temperature of the second liquid coolant passing through the cold plate is higher compared to the configurations of FIGS. 4A-5B (because the second liquid coolant has already received heat transferred from the first liquid coolant). As a result, the cooling power of the second cooling circuit at the cold plate may be reduced compared to the configurations of FIGS. 4A-5B. However, in the configurations of FIGS. 4A-5B, the temperature of the second liquid coolant in the heat exchanger is relatively lower than that of the second liquid coolant in the heat exchanger, so the cooling power of the second liquid coolant in the heat exchanger is increased compared to the configurations of FIGS. 4A-5B. In fact, the inventors have recognized that in many scenarios, the configurations of FIGS. 4A-5B can provide better overall cooling performance for the entire electronics module. This configuration may be particularly beneficial when more high-temperature auxiliary components are included on the PCB within the electronics module (and are partially immersed in the first liquid coolant).

[0243] A system with a second cooling circuit having a cold plate and a heat exchanger in parallel. Referring to Figure 8A, a specific implementation of the example electronic module 100 described above with reference to Figures 3A and 3B (where the cooling module and heat exchanger are arranged in parallel within a second cooling circuit) is depicted. The electronic module may be a module or a server blade, with appropriate dimensions and external connectors to fit within a typical server rack (not shown). The same electronic module 100 is shown in Figures 8B and 8C, each showing a different perspective view of the module.

[0244] The electronic module has an outer housing or enclosure 110, which may have a base, walls, and a lid, and may be hermetically sealed. Multiple electronic devices (or heat-generating components) are mounted within the housing. In some cases, the components may be mounted on a printed circuit board (PCB) 120, which may be connected to the base, lid, or walls of the housing. The described system is intended to remove heat generated by the electronic devices from within the electronic module.

[0245] The first cooling circuit (or first cooling loop) is used to cool a specific electronic device among the multiple electronic devices mounted in the electronic module, and the second cooling circuit (or second cooling loop) is used to cool other heat-generating components. For example, the second cooling circuit may be provided with a greater cooling power and therefore may be used to cool a specific component that generates a greater amount of heat than the component cooled by the first cooling circuit.

[0246] In the example depicted in Figures 8A, 8B, and 8C, the electronics module has a first cooling circuit (or first cooling loop) that provides immersion cooling. The first cooling circuit is contained entirely within the housing 110 of the electronics module. In particular, a first liquid coolant is contained within the sealable housing of the electronics module, and several components 115 to be cooled are at least partially immersed in the first liquid coolant. The first liquid coolant is contained within the volume of the housing of the electronics module and can be thought of as a reservoir of the first liquid coolant.

[0247] The first liquid coolant from the first liquid coolant reservoir is collected or received at pump inlet 190. Pump inlet 190 may be shaped to improve the flow of liquid coolant toward pump 185. Pump 185 moves the first liquid coolant through a first cooling circuit (or first cooling loop). The first liquid coolant is pumped through the pump 185 and travels through pipe 195 into heat exchanger 170 (and across thermally conductive interfaces therein), where it is cooled. In particular, heat retained in the first cooling fluid may be transferred through the thermally conductive interfaces to a second cooling fluid, as described below, which also passes through the heat exchanger. As will be appreciated, the first liquid coolant entering the heat exchanger is at a higher temperature than the first liquid coolant exiting the heat exchanger.

[0248] In the examples of FIGS. 8A, 8B, and 8C, a pipe 200 is connected to the heat exchanger 170 to carry the first cooling fluid. The distal end of the pipe 200 has one or more outlets or nozzles 205a, 205b. In the particular example of FIGS. 8A, 8B, and 8C, the outlet or nozzle 205a forms an inlet to weirs 202a, 202b, respectively. The weirs act as heat sinks and are part of the first cooling circulation system. Weirs are described in more detail below with respect to FIGS. 12A-14B. However, the first cooling circulation system can be configured without the weir heat sinks described above. For example, the nozzles can be positioned to distribute the first liquid coolant exiting the heat exchanger near the first electronic device, or to direct the first liquid coolant through a reservoir of first liquid coolant within the housing or chassis (in which the first electronic device is at least partially immersed) toward a pump inlet.

[0249] The first cooling fluid exits outlets or nozzles 205a, 205b and passes through weirs 202a, 202b (if used) until it collects in a reservoir of first liquid coolant contained within the volume of housing 110 of electronic module 100. In this manner, the cooler first liquid coolant that passed through the heat exchanger can be reintroduced into the first liquid coolant tank or reservoir within housing 110 to cool any electronic components partially immersed in the reservoir. Specifically, the cooled first liquid coolant will absorb heat from surfaces of electronic devices (including the first electronic device with which it is in contact). Eventually, the first liquid coolant is recollected at the pump inlet, thereby completing its flow through the first cooling circuit (or first cooling loop).

[0250] FIGS. 8A, 8B, and 8C also depict a second cooling circulation apparatus. The second cooling circulation apparatus incorporates one or more cooling modules or cold plates 125a, 125b, each mounted to one or more electronic devices. Ideally, the electronic devices require higher-performance cooling. The cold plates 125a, 125b are modules or chambers through which a second liquid coolant (such as water) can be passed. Heat can be transferred from the electronic devices 130a, 130b to the second liquid coolant within the cold plates by thermal conduction through the mounting surface of the cold plate coupled to the given electronic device. The cold plates 125a, 125b of the second cooling circulation apparatus are discussed in more detail below with respect to FIGS. 10A, 10B, and 10C. The second cooling circulation apparatus of FIGS. 8A, 8B, and 8C has two cold plates connected in parallel, but they could also be connected in series, for example.

[0251] 8A, 8B, and 8C, an inlet 145 in a wall of the housing of the electronics module is connected to a two-way inlet manifold 221 disposed within the housing of the electronics module. The two-way inlet manifold 221 creates two parallel branches of a second cooling circuit within the electronics module. The inlet 145 includes a connector, which may be any suitable type of connector, including a quick-disconnect connector. A second liquid coolant is received into the electronics module via the inlet 145.

[0252] In the first branch of the second cooling circuit, the first inlet conduit 135 is connected to a two-way inlet manifold 221 for transporting the second liquid coolant to a further inlet manifold 150. The second and third inlet conduits 140a, 140b are connected to the further inlet manifold. The second and third inlet conduits 140a, 140b are each connected to a respective cold plate 125a, 125b. In this way, the second cooling fluid is supplied to the electronic modules. The second liquid coolant may be transported in parallel to each of the cold plates 125a, 125b in the chamber. The second liquid coolant is then passed through the cold plates, as discussed below with respect to Figures 10A, 10B, and 10C.

[0253] An exhaust conduit 155a, 155b is connected to each of the respective cold plates 125a, 125b. The exhaust conduits 155a, 155b receive the second liquid coolant exhausted from each of the cold plates 125a, 125b in parallel. The exhaust conduits 155a, 155b are connected to a further exhaust manifold 160 which is connected to an exhaust conduit 165. The exhaust conduit 165 conducts the second liquid coolant to a two-way outlet manifold 251, at which point the first and second branches of the second cooling circuit join together.

[0254] In the second branch of the second cooling circuit, the outlet to the two-way inlet manifold 221 is directly connected to the inlet of the heat exchanger 170. The second liquid coolant in the second branch of the second cooling circuit flows across a thermally conductive interface in the heat exchanger, through which heat is transferred to the second liquid coolant, forming the first liquid coolant. The heat exchanger 170 is disposed entirely within the electronic module housing 110. In the particular example of Figures 4A, 4B, and 4C, the heat exchanger 170 is a plate heat exchanger. However, other suitable types of heat exchangers can be used.

[0255] The heat exchanger 170 may be of any suitable type that allows heat exchange between a first coolant fluid and a second coolant fluid while maintaining separation (not mixing) of the two liquid coolants. For example, the heat exchanger may have a first chamber through which a first liquid coolant flows, separated from a second chamber through which a second coolant flows. The wall(s) separating the first and second chambers act as a thermal interface (or thermally conductive interface), through which heat may be transferred. In particular, heat may be transferred from a hotter liquid coolant (in this example, the second liquid coolant under normal operation) to a colder liquid coolant (in this example, the first liquid coolant under normal operation) as a result of a temperature gradient across the thermal interface. As can be envisioned by one skilled in the art, more than two chambers may be included in the heat exchanger, and more than two thermal interfaces may be provided to separate chambers through which different liquid coolants flow. More than two paths through a given chamber may be provided. The heat exchanger may include fins or other features on the thermal interface surface to facilitate heat exchange.

[0256] 8A, 8B, and 8C, the outlet of the heat exchanger is directly connected to a two-way outlet manifold 251, which rejoins the first and second branches of the second cooling circuit. The two-way outlet manifold 251 is coupled to an outlet 180 in the wall of the housing of the electronics module. The outlet 180 includes a connector, which may be any suitable type of connector, including a quick-disconnect connector.

[0257] Although not shown in Figures 8A, 8B, and 8C, inlet 145 and outlet 180 may each be connected to a cooling system or a second liquid coolant supply (e.g., by additional piping connected to inlet 145 and outlet 180, if desired). This is discussed in more detail below with respect to Figures 9A and 9B.

[0258] Advantageously, the parallel configuration of the second cooling circuit allows both the cold plate and the heat exchanger to benefit from the lowest temperature second liquid coolant. Furthermore, this configuration allows for balancing the flow rate (and cooling performance) in the heat exchanger relative to the cold plate. Thus, this configuration may allow for greater control over the cooling of the second and third electronic devices via the cold plate and the cooling of the first electronic device via the first liquid coolant by adjusting the ratio of the second liquid coolant through each of the first and second branches of the second cooling circuit within the housing of the electronic module.

[0259] 9A and 9B show schematic diagrams of the first and second cooling circulation devices of FIGS. 8A, 8B, and 8C when the electronic module 100 is connected in a rack 400. The arrangement of the first and second cooling circulation devices within the electronic module is the same for both examples of FIGS. 9A and 9B. However, the apparatus for providing the low-temperature second liquid coolant to the electronic module is different in the two examples of FIGS. 9A and 9B. In particular, the external cooling system for providing the second liquid coolant in the example of FIG. 9A is the same as the external cooling system described above with reference to FIG. 1A (i.e., heat transfer from the second liquid coolant to a third coolant medium via an additional heat exchanger). The external cooling system for providing the second liquid coolant in the example of FIG. 9B is the same as the external cooling system described above with reference to FIG. 1B (i.e., a supply of second liquid coolant from a facility-level supply, such as a chilled water supply).

[0260] 9A and 9B, a first cooling circulation system is shown having a pump inlet 190, a pump 185, a heat exchanger 170, and a weir 202 for circulating a first liquid coolant 401 within the housing of the electronic module 100. Figures 9A and 9B further show a second cooling circulation apparatus comprising first and second cooling modules (or cold plates) 125a, 125b, and the heat exchanger 170.

[0261] During use, the second liquid coolant is received into the electronics module through inlet 145 and immediately splits into first and second branches. The first branch delivers the second liquid coolant to two cooling modules (or cold plates) 125a, 125b arranged in parallel. After passing through cooling modules (or cold plates) 125a, 125b, the second liquid coolant from the first branch rejoins the second branch and then exits the electronics module via outlet 180. Inlet 145 and outlet 180 may be connected to an inlet manifold 405 or an outlet manifold 410, respectively, in a server rack 400 in which electronics module 100 is mounted. Inlet 145 and outlet 180 may be connected to inlet manifold 405 and outlet manifold 410 of server rack 400 via quick-disconnect connectors.

[0262] In use, the second branch of the second cooling circuit passes a portion of the second coolant through heat exchanger 170. Within heat exchanger 170, heat is transferred from the first liquid coolant within the first cooling circuit to the second liquid coolant. Once the portion of the second liquid coolant has passed through heat exchanger 170, it then rejoins the first branch of the second cooling circuit and then exits the electronic module directly via outlet 180.

[0263] Cooling module (or cold plate) The cooling module of the second cooling circuit may be provided as a cold plate. Such cold plates are described in more detail below with reference to FIGS. 10A-10C. Cold plates have particular advantages for providing high-performance, efficient cooling of the particular electronic device to which they are coupled. In this manner, the second cooling circuit, or more specifically, the cold plate, may be coupled to the electronic devices within the electronic module that generate the greatest amount of heat. While it may be impractical to cool all of the electronic devices within the electronic module in this manner, the use of a cold plate as part of the second cooling circuit allows for concentrated cooling, which can reduce the burden of cooling the entire volume of the electronic module by the first cooling circuit. In this manner, the first and second cooling circuit operate in conjunction to provide a particularly efficient and effective cooling system for the electronic module.

[0264] A further advantage of the cold plate in the second cooling circuit is the provision of a closed, sealed system, where the second liquid coolant does not come into direct contact with any electronic devices. This allows for the use of water for the second liquid coolant (e.g., not a dielectric liquid), which is low cost and readily available. The second cooling circuit can be connected to the facility's water supply and drain, or If the second cooling circuit is connected to a powerful pumping system external to the electronic module, a large throughput of water through the second cooling circuit is possible, which further increases the potential cooling power of the second cooling circuit.

[0265] Generally, described herein is a cold plate comprising a housing (which may be integrally formed), the housing having a surface (typically planar) arranged to provide a thermal interface (which may be referred to as a conduction surface) for cooling an electronic device thermally coupled to the housing. The cold plate further comprises at least one channel within the housing and proximate to the surface. The channel(s) may be formed from an internal chamber(s), volume, or other space for containing a liquid coolant (such as water, a water-based coolant, a coolant essentially comprising water, or a liquid substitute with a high specific heat capacity, such as mineral oil or a dielectric fluid). The channel(s) are arranged such that a liquid coolant flows therethrough such that heat received by the thermal interface is transferred to the liquid coolant. Optionally, multiple parallel channels may be provided, each extending from a coolant port. As discussed further below, pins and / or fins are preferably disposed within at least one channel.

[0266] The cold plate also includes a coolant port extending outside the housing for transporting liquid coolant to and / or from at least one channel. The coolant port may be a connector, coupling, joint, or other similar structure. Inlet and outlet coolant ports may be provided. At least one conduit, such as a pipe, hose, or tube (preferably flexible), may be coupled to the coolant port for transporting liquid coolant to and / or from the coolant port. Advantageously, the cold plate is configured such that the liquid coolant remains in a substantially liquid state (i.e., single-phase liquid cooling) throughout the cooling system.

[0267] Referring first to FIG. 10A , an embodiment of a cold plate (or cold plate assembly) 1200 for use as a cooling module in a secondary cooling circuit is shown. In particular, the cold plate is advantageous for use in an electronic module or server blade (or similar module). The cold plate assembly includes a cold plate housing 1210 (preferably integrally formed), connectors 1220 a, 1220 b forming inlet / outlet ports for the cold plate, and inlet / outlet conduits 1225 (here, pipes or tubing). Also shown are fixing points 1230 for the cold plate 1200. These fixing points may beneficially replicate those found on air-cooled heat sinks in a typical server chassis, allowing the cold plate to be retrofitted to a server blade.

[0268] In a preferred example, multiple coolant ports 1220a, 1220b are used, as shown in FIG. 10A . A first coolant port 1220a is then provided for transferring liquid coolant into the cold plate 1200, and a second coolant port 1220a is provided for transferring liquid coolant from the cold plate 1200. In the example of FIG. 10A , the coolant ports 1220a, 1220b are coupled to independently rotating fluid connectors (or swivel joints or swivel elbow connectors, these terms are used interchangeably herein), thereby allowing for adjustment of the orientation of the inlet / outlet conduits 1225a, 1225b coupled to the coolant ports 1220a, 1220b. As such, this type of connector is particularly useful for configuring or installing the cold plate assembly for operation. The swivel joints can increase flexibility in cold plate placement. This can more easily allow for retrofitting the cold plate into an existing electronic module, such as a server or any other computer system, without the need for other modifications to the unit or system. The cold plate may be configured to fit in place of, for example, an air-cooled heat sink.

[0269] Preferably, the surface arranged to provide a thermal interface with an electronic device (such as a second electronic device) to which the cold plate is coupled is the bottom surface of the cold plate housing (e.g., the not-shown lower surface of the cold plate housing 1210 in FIG. 10A ). Coolant ports 1220a, 1220b are then advantageously provided on the top surface of the housing 1210 opposite the bottom surface. In a preferred embodiment, the coolant ports extend in a direction perpendicular to the top surface of the housing. A swivel joint can then allow the coolant ports to extend in different directions, typically more parallel to the top surface of the housing. Advantageously, the swivel joint allows the direction of the pipe to be adjusted around an axis perpendicular to the top surface of the housing. In particular, the swivel joint may allow the direction of the pipe to be adjusted by at least 90 degrees, 180 degrees, 270 degrees, and preferably up to (and including) 360 degrees, especially around an axis perpendicular to the top surface of the housing. Thus, the swivel connector may allow full rotational freedom of the coolant ports.

[0270] In principle, a single coolant port can provide both the inlet and outlet for liquid coolant to the channels. In a preferred embodiment, multiple coolant ports are used, as shown in FIG. 10A. The coolant port is then a first coolant port for transferring liquid coolant to at least one channel. The cold plate may include a second coolant port for transferring liquid coolant from at least one channel.

[0271] The housing of the cold plate and the arrangement of ports on the cold plate can take any shape useful for facilitating the flow of coolant through the cold plate and to the portion of the second electronic device to which the cold plate is coupled. In some examples, the housing is elongated, and the first and second coolant ports are positioned at opposite ends of the housing along the elongation direction, which may facilitate the flow of liquid coolant across the thermal interface surface and / or aid in flexible positioning of the cold plate. Additionally or alternatively, the second coolant port (like the first coolant port) may include a swivel joint, thereby allowing for adjustment of the direction of a pipe coupled to the second coolant port. Providing two coolant ports, each with a swivel joint, may enable improved methods of coupling cold plates within a cooling system, including the possibility of coupling cold plates together.

[0272] Referring to Figure 10B, a top internal (plan) view of an exemplary cold plate according to the example of Figure 10A is depicted, with the lid and nozzle removed for clarity.

[0273] 10B shows coolant inlet port 1225a, coolant outlet or exhaust port 1225b, coolant flow channel 1235, and pins 1240. It can be seen that a flow channel is formed between coolant inlet port 1225a and coolant outlet or exhaust port 1225b through which a second liquid coolant can flow when the cold plate is in use. This configuration, and particularly the configuration of pins 1240, distributes the coolant flow in all directions within the cold plate, allowing the coolant to spread evenly across the cold plate.

[0274] 10C, a side (cross-sectional) view of the embodiment of FIG. 10B is shown with connectors coupled to ports 1225a, 1225b and cold plate base 1245. Also shown is cold plate lid 1250. Base plate 1245 and lid 1250 may together form cold plate housing 1210 shown in FIG. 10A. As shown in FIG. 10C, pins 1240 are connected to base 1245 and lid 1250. This may prevent the flow of liquid coolant through the channels from shortcutting or bypassing the pins. In this manner, the pins can direct the flow of coolant into the cold plate.

[0275] The base plate 1245 can provide a thermal interface to which a second electronic device can be coupled. In particular, the cold plate 1200 can be mounted to an electronic device (e.g., a second or third electronic device as described with reference to FIGS. 1A-3B ) with the base plate 125 of the cold plate in direct contact with a surface of the second electronic device. In this manner, heat can be transferred from the surface of the electronic device through the thermal interface provided by the base plate 1245 to the liquid coolant flowing within the cold plate.

[0276] Weir heat sink Weirs in the first cooling circulation system will now be described in more detail with reference to FIGS. 11A-13B. Weirs offer particular advantages for directing and increasing the flow of the first liquid coolant in the first cooling circulation system. By using weirs, the first liquid coolant can be directed to flow over or through specific regions of the electronic module and any electronic devices mounted therein. In some examples, the base of the weir can be coupled to the first electronic device (or another electronic device) and thus act as a heat sink for the coupled device. In alternative examples, the electronic device can reside within the volume of the weir. Additionally, the use of weirs allows for a reduction in the level of first liquid coolant required in the electronic module, as discussed further below. This is particularly important when maintaining the liquid level of the first liquid coolant at a sufficiently low level to avoid contact with the cooling module or cold plate in the second cooling circulation system.

[0277] Referring first to FIG. 11A , a first embodiment of a weir or weir heat sink for use in a first cooling circulation system is shown. Referring to FIG. 11B , an exploded view of the embodiment of FIG. 11A is shown. Weir 600 comprises a base consisting of a mounting portion 610 and a planar substrate 615 secured to mounting portion 610, a retaining wall 620 attached to planar substrate 615, protrusions (shown in the form of pins) 625, and a set screw 630 that attaches substrate 615 to mounting portion 610. In this manner, planar substrate 615 sits directly on a high-temperature component, which may be a first electronic device 635. In this manner, heat is transferred from first electronic device 635 to a volume defined by planar substrate 615 and retaining wall 620, on which protrusions 625 are provided.

[0278] Weir heat sink 600 can be fabricated from a single component by, for example, die casting, lost wax casting, metal injection molding (MIM), additive manufacturing, or forging. Weir heat sink may also be machined or milled from a block of material. Weir heat sink 600 can be formed from any material that is thermally conductive, such as a metal or other thermal conductor. Some examples may include aluminum, copper, or carbon.

[0279] 11A and 11B also show the inlet to the weir at pipe 640 and nozzle 645. A first liquid coolant is delivered to weir heat sink 600 via nozzle 645. Nozzle 645 is positioned to direct the coolant perpendicular to the plane of substrate 615. This forces a jet or stream of liquid coolant directly into the volume defined by substrate 615 and retaining wall 620 of heat sink 600. This results in improved heat dissipation. This is especially true compared to systems, such as air-cooled systems, where the coolant is directed to flow over the heat sink in a direction parallel to the plane of the heat sink substrate.

[0280] 11A and 11B, the nozzle 645 delivers coolant directly to the center of the volume defined by the substrate 615 and the retaining wall 620. In this example, the center of that volume corresponds to the hottest portion of the area of ​​the substrate 615 adjacent to (and directly above) the hot component 635. This provides a counterflow so that the coldest coolant reaches the hottest portion of the weir heat sink. The coolant is directed to contact the hottest area in a radial direction.

[0281] Referring to FIG. 11C, a cross-sectional view of the weir heat sink of FIG. 11A is shown in operation. Features that are the same as those shown in previous figures are identified by the same reference numerals. Arrows indicate the flow of coolant in pipes 640 to provide first liquid coolant 805 within the volume defined by the substrate 615 and the retaining wall 620 of the heat sink 600, and to provide first liquid coolant 810 outside the heat sink 600. As previously shown, first liquid coolant exiting nozzles 645 is directed to the center of the volume (corresponding to the center of the surface area of ​​the substrate 615) and travels radially outward from there toward the retaining wall 620. Sufficient first liquid coolant is pumped through nozzles 645 into the volume, causing it to overflow 810 over the retaining wall 620 and collect with the remaining first liquid coolant 815 outside the weir heat sink 600.

[0282] In an alternative embodiment, the first liquid coolant held within the weir may be discharged through holes in the base or sidewall of the weir to facilitate flow of the first liquid coolant. In a further variation, the first electronic device may be positioned within the volume of the weir rather than being coupled to the exterior surface of the weir.

[0283] The retaining walls 620, acting as side walls, allow for different levels of coolant: a first liquid coolant 805 within the volume of the weir heat sink 600 is at a relatively high level, and a coolant 815 that at least partially immerses multiple other electronic devices within the electronic module (not shown in this drawing) is at a lower level. This allows for the use of significantly less liquid coolant than other similar systems that cover all components at the same height.

[0284] This achieves several advantages. First, when a dielectric coolant is used as the first liquid coolant, less of the first liquid coolant is used. This has two main advantages: dielectric coolants can be expensive, thus significantly reducing costs, and dielectric liquid coolants are typically very heavy, thus reducing the weight of the electronic module. Furthermore, by using less liquid coolant, the electronic module 100 can be more easily installed and / or lifted. Installing the electronic module 100 also requires less infrastructure. Furthermore, the electronic module 100 is easier to handle than similar devices that use significantly more primary liquid coolant. The level of the first liquid coolant 815 in the majority of the vessel 110 is not near the top of the vessel. As a result, spills are less likely to occur during component maintenance or replacement. The risk of leaks is also reduced.

[0285] The retaining wall 630 creates a weir effect, promoting the flow of the first liquid coolant. The coolant 815, at a relatively low level, cools the electronic devices (first electronic device and any other electronic devices) within the electronic module 100. The first electronic device and any other electronic devices do not need to be completely immersed in the first liquid coolant. The first liquid coolant retained in the weir heat sink 600 may also provide some redundancy in cooling for the first cooling circuit in the event of a failure of the pump 185 or other component.

[0286] 12, a top view of the embodiment of FIG. 11A is shown showing the nozzle arrangement. As previously described, nozzle 645 is coupled to pipe 640. Nozzle 645 is positioned to face the center of the surface area of ​​substrate 615 (not shown in this view). The radial flow of coolant is indicated by arrows in this view.

[0287] Alternative locations for the nozzle 640 are possible. Reference is now made to Figure 13A, which shows a top view of a first variation of the nozzle arrangement of the embodiment of Figure 11A, and Some such locations are described with reference to FIG. 13B, which shows a top view of a second variation of nozzle placement. Referring first to FIG. 13A, nozzle 645 is shown off-center. Such placement may be provided when the hottest portion of the first electronic device (to which weir heat sink 600, not shown, may be bonded) is not adjacent to the center of substrate 615. Referring to FIG. 13B, two nozzles are shown. The two nozzles 645 are positioned over surface areas of substrate 615 (not shown) adjacent to two of the hottest portions of the first electronic device (to which weir heat sink 600, not shown, may be bonded).

[0288] The protrusions 625 (as pins and / or fins) may be integrally formed with the rest of the weir heat sink 600 or may be made from separate components. The protrusions 625 may be tolerance-fit, glued, or brazed in place. Additionally or alternatively, the retaining wall 620 may be integrally formed with the rest of the heat sink 600 or made separately, for example, by extrusion or fabricated sheet metal part. The retaining wall 620 may then be tolerance-fit, glued, brazed, or welded in place.

[0289] First liquid coolant liquid level The use of heat exchangers as separate, specific components for transferring heat between the first and second liquid coolants provides improved control over the overall system's cooling performance. The cooling power of each component within the first and second cooling circuits depends, at least in part, on the temperature gradient between the liquid coolant and the component to be cooled. In particular, larger temperature differences typically result in greater heat transfer than smaller temperature differences. The cooling system configuration described above (where heat exchange between the first and second liquid coolants occurs primarily in the heat exchanger) allows for the selection of the most advantageous combination of temperature gradients or temperature differences for each component to be cooled.

[0290] In particular, it has been determined that it is advantageous to thermally separate the first and second liquid coolants except for the control area of ​​the system (particularly within the heat exchanger). It has been found that the cooling performance of a cooling module (or cold plate) is significantly reduced when the cooling module is directly thermally coupled to the first liquid coolant. Specifically, in systems where the first cooling circuit provides immersion cooling and the first liquid coolant at least partially immerses the cooling module or cold plate, the performance of the cooling module is, in turn, reduced. As a result, it has been found desirable to avoid direct contact between the cooling module (or cold plate) and a reservoir of first liquid coolant contained within the housing or chassis of the electronic module.

[0291] One option for achieving this goal is to position the cooling module within the housing of the electronic module relative to the first electronic device so that, when the system is in use, the cooling module is above the highest liquid level of the volume of first liquid coolant contained within the chassis of the electronic module, while the first electronic device is positioned so that it is at least partially immersed in the first liquid coolant. In this case, the first electronic device is positioned within the housing so that, when the electronic module is disposed in a rack, the base of the first electronic module is below the base of the cooling module. In other words, all surfaces of the cooling module are above the highest level of the first liquid coolant contained within the electronic module when the electronic module is disposed in a rack.

[0292] Such advantageous configurations require appropriate selection of the volume of the first liquid coolant (to maintain an appropriate first liquid coolant level). The required liquid level may be lower than that expected in a typical immersion cooling system. The lower level of the first liquid coolant may be made possible by the superior overall cooling performance of the described system. Furthermore, The use of a weir heat sink within the first cooling circulation system (as described in more detail with reference to Figures 11A-13B) may also allow for a reduction in the overall volume of the first liquid coolant (and therefore its liquid level) while still maintaining good cooling performance. Reducing the volume of first liquid coolant required in the system may also reduce the cost and weight of the sealed electronic module.

[0293] FIG. 14 is a cross-sectional view of an electronic module showing the placement of a liquid level 50 of a first liquid coolant contained within the housing of the electronic module relative to the cooling module (or cold plate) 14. In particular, it can be seen that the base of the cold plate 14 is above the first liquid coolant level 50, and that neither the sidewalls nor the top surface of the cold plate 14 are submerged in the first liquid coolant. It can be seen that a second electronic device 55, to which the cold plate is thermally coupled, is fully submerged in the first liquid coolant. Connections to the cold plate 14 (such as exhaust conduit 1225b) are also maintained above the liquid level of the first liquid coolant. A portion 60 of the cavity within the housing of the electronic module is at approximately the first liquid coolant level and is not filled with liquid coolant (either the first liquid coolant or the second liquid coolant).

[0294] An alternative option for thermally isolating the cooling module (or cold plate) from the first liquid coolant is to thermally isolate the cooling module (or cold plate) on the exterior surfaces of the side and / or top walls of the cold plate. However, this option can be complex, can increase the size and volume of the cold plate (which is undesirable within the confines of an electronics module housing), and can add cost. Therefore, as discussed above, control of the first liquid coolant level may be preferred.

[0295] Rack-Mounted Electronic Modules 15A and 15B show an example of multiple electronic modules 2500 according to the above example mounted in a rack 2510. In FIGS. 15A and 15B, a second cooling circuit is connected to the rack-level cooling system. In particular, multiple electronic modules are connected in parallel. Each electronic module may be of the type described above with reference to FIGS. 1A-9B.

[0296] In the example of Figure 15A, a single external cooling system of the type described with reference to Figure 1A above is used to cool a secondary liquid coolant supplied to each of the electronic modules 2500 in the rack 2510. In other words, the second liquid coolant is cooled via a second heat exchanger and heat is transferred to a third liquid coolant or coolant medium.

[0297] In FIG. 15B, the second liquid coolant of the second cooling circulation device is supplied (and constantly replenished) with a lower temperature second liquid coolant by connection to a facility-level cooling system, such as the facility-level chilled water system supplied by the main water described above with reference to FIG. 1B.

[0298] A system including a second cooling circuit with a parallel cooling module (or cold plate) and a thermally conductive mating surface in the heat exchanger. As mentioned above, various systems for cooling multiple electronic modules utilize a heat exchanger 18. The heat exchanger 18 resides within the housing of the electronic module 10. The heat exchanger 18 is used to transfer heat from a first cooling liquid in a first circulation system 20 (which typically circulates through the housing and at least partially submerges a portion of the electronic device 12 within the housing) and a second cooling liquid in a second circulation system 22 (which typically circulates through the cold plates 14, 16 and / or the heat exchanger 18, depending on whether a series or parallel configuration of cold plates and heat exchangers is used). Heat is transferred from the first cooling liquid to the second cooling liquid in the heat exchanger 18.

[0299] As mentioned above, the heat exchanger 18 used in the described system can be a plate heat exchanger. A plate heat exchanger includes at least a first chamber and a second chamber, which are separated from each other by a thermally conductive interface (within at least some portion of each chamber). Such a heat exchanger 18 is configured for the flow of a first liquid coolant through at least the first chamber and a second liquid coolant through at least the second chamber. As the respective coolants flow through the respective chambers, heat is transferred from the first liquid coolant to the second liquid coolant through the thermally conductive interface. Typically, each chamber has a single inlet and outlet port to allow the respective liquid coolant to flow through a given chamber. The chambers are thermally coupled by not being fluidly coupled, so that the first and second liquid coolants do not mix within the heat exchanger.

[0300] The plate heat exchangers described above can be used in any of the system configurations described above with reference to FIGS. 1A-3B (including systems in which the heat exchanger is disposed in series with the cold plate or systems in which the heat exchanger is disposed in parallel with the cold plate). Such heat exchangers require the use of appropriate connectors between the various components of the system. For example, providing the system of FIG. 8A , in which cold plates 125 a, 125 b are disposed in parallel with a typical plate heat exchanger 170, requires the use of a bidirectional inlet manifold 221 between the inlet 145 in the wall of the housing and the heat exchanger 170, and a bidirectional outlet manifold 251 between the outlet 180 in the wall of the housing and the heat exchanger 170. While such a configuration operates effectively, the bidirectional inlet manifold 221 and the bidirectional outlet manifold 251 require additional space within the volume of the electronic module housing 110. To maximize the space available for cooling electronic devices, it is preferable to reduce the space occupied by the cooling system within the volume of the housing 110.

[0301] With this in mind, a novel configuration for a heat exchanger has been proposed by the inventors. The novel configuration for the heat exchanger is described with reference to Figures 16-18, and implementation of the novel heat exchanger in a system having a parallel branch of a second circulating cooling device is discussed with reference to Figures 19A-22B. While the use of the novel configuration for the heat exchanger is discussed with particular reference to a system having a parallel configuration of second circulating cooling devices, it will be understood that a similar configuration for the heat exchanger can be used in a system having a series configuration of second circulating cooling devices (having a cooling module and a mechanism for heat exchange with a first liquid coolant in series), as discussed with respect to the systems of Figures 1A and 1B and 2A and 2B above.

[0302] An example of the flow through the novel configuration of heat exchanger 700 is shown in FIG. 16. An example of the internal structure of the same heat exchanger is shown in FIG. 17. The heat exchangers of FIGS. 16 and 17 have parallel feeds through the heat exchanger's thermally conductive interface. However, the novel configuration of heat exchanger 700 can also employ a series feed to the thermally conductive interface, as shown in FIG. 18. However, the general concept of the heat exchangers of FIGS. 16 and 17 and the heat exchanger of FIG. 18 is the same in that the second chamber has two inlets (inlet ports) and two outlets (outlet ports) and at least two paths therethrough. Each path provides a path for liquid coolant between a different combination of inlet and outlet ports, and at least one of the paths does not pass through or contact a thermally conductive interface through which heat can pass to other chambers of the heat exchanger. All paths are fluidly connected and within the same chamber of the heat exchanger, which is fluidly isolated from any other chamber of the heat exchanger.

[0303] Similar to the typical configuration of the plate heat exchangers described above, each of the heat exchangers shown in Figures 16, 17, and 18 comprises first and second chambers separated from one another by a thermally conductive interface 705. The first chamber is arranged to have a first cooling liquid flow therethrough, and the second chamber is arranged to have a second cooling liquid flow therethrough. The wall 795 of the module housing or chassis is depicted in Figure 16. The body of the heat exchanger (the portion of the heat exchanger containing the first and second chambers and the thermally conductive mating surfaces) resides within the housing or chassis.

[0304] A first cooling liquid flows through the first chamber on a path 710 (marked by dashed arrows in FIGS. 16, 17, and 18) between a single inlet In1 (inlet port 715) and a single outlet Out1 (outlet port 720). The first cooling liquid traveling on its path through the first chamber passes through and contacts one or more thermal interface surfaces 705, which allow heat transfer to (or from) another liquid coolant on the other side of the thermal interface surface 705, according to the temperature gradient between the two liquids at the interface. However, the thermal interface surfaces 705 act as a physical barrier between the first and second chambers (thus preventing the first and second liquid coolants from mixing).

[0305] In the heat exchangers shown in Figures 16, 17, and 18, the path 710 through the first chamber always extends from the first inlet In1 (inlet port 715) to the first outlet Out1 (exhaust port 720) into the first chamber. However, it can be seen that in the heat exchangers depicted in Figures 16 and 17, the path through the first chamber comprises parallel branches that pass through different thermally conductive mating surfaces (or thermal plates). In contrast, the path through the first chamber of the heat exchanger shown in Figure 18 passes through the thermally conductive mating surfaces (or thermal plates) in series.

[0306] The second chamber of the heat exchanger shown in Figures 16, 17 and 18 has two inlets In 2A+2B and In 2B (Injection ports 725, 730) and two outlets Out 2A and Out 2B+2C (exhaust ports 735, 740). In all cases, three paths are defined through the second chamber, each path directing the second liquid coolant between a different combination of inlet and outlet ports.

[0307] The first path 745 (dotted arrow in FIGS. 17 and 18) connects the first second chamber inlet In 2A+2B (Injection port 725) to the first second chamber outlet Out 2A The second path 750 (solid arrow in FIGS. 17 and 18) leads directly to the first second chamber inlet In 2A+2B The gas is guided from the inlet port 725, passes through one or more thermal interface surfaces 705 with the first chamber, and then exits the second chamber outlet Out 2B+2C (exhaust port 740). Finally, a third path 755 (dashed arrow in FIG. 16) leads to the second chamber inlet In 2C (Injection port 730) directly to the second chamber injection port Out 2B+2C The first and second channels 745 and 750 are connected to a common inlet, the first and second chamber inlet In 2A+2B , while the second path 750 and the third path 755 share a common outlet, the second chamber inlet Out 2B+2C However, the first path 745 has an individual, non-shared outlet, the first second chamber outlet Out 2A and a third path 755 is an individual, non-shared inlet, a second chamber inlet In 2C All three paths 745, 750, 755 through the second chamber are fluidly connected and physically (and fluidly) separated from the first chamber.

[0308] It will be appreciated that the second path through the heat exchangers of Figures 16 and 17 is of a different configuration than the second path contemplated by the heat exchanger of Figure 18. However, in both cases the second path is a first second chamber inlet In 2A+2B (inlet port 725), through one or more thermal interface surfaces 705 with the first chamber, and through the second chamber outlet Out 2B+2C(exhaust port 740). In particular, the second path in the heat exchangers of Figures 16 and 17 passes through one or more thermal interface surfaces 705 on parallel branches of the second path, while the second path in the heat exchanger of Figure 18 passes through one or more thermal interface surfaces 705 in a series configuration. In the examples, it will be understood that the particular path through the second chamber is not limited, other than the requirement that the second path be through a thermally conductive interface, whereas the first and second paths are not.

[0309] The second cooling liquid entering the second chamber of the heat exchanger described above can take one of three paths 745, 750, 755. The proportion of the second liquid coolant taking each path depends on the relative flow rates through each path and the point of entry. Only the second path 750 contacts the thermal interface surface 705, and heat is transferred from the first liquid coolant in the first chamber. Thus, heat transfer from the first liquid coolant to the second liquid coolant ideally occurs primarily over the second path 750, such that at least the second liquid coolant on the first path 745 does not receive any of the heat transferred through the thermal interface surface 705.

[0310] In the configuration described, each chamber can be considered a portion of the heat exchanger 700 that is physically separate from any other chamber within the heat exchanger 700. Cooling fluid in a first chamber cannot enter a second chamber via any path within the body of the heat exchanger 700. Different paths may be provided through each chamber, but the various paths will meet and merge with another path at one or more points along their length. The merging points may be at a common inlet or outlet (e.g., In 2A+2B , or Out 2B+2C ) or may be the result of the confluence or intersection of two pathways within a chamber. Although each individual pathway within a chamber may not intersect and / or be in direct contact with every other individual pathway within the chamber, all pathways within a single given chamber are fluidly connected.

[0311] It will be understood that a path through a chamber represents a passage between a given first and second point (inlets and outlets to the chamber). Fins or other protrusions may be provided between these points, or other mechanisms for increasing surface area for heat transfer. A particular path may have a series configuration (such as the second path shown in FIG. 18) or may have parallel branches that themselves pass through the chamber (such as the second paths shown in FIGS. 16 and 17). However, a fluid is considered to pass through a single path if the starting and ending points (inlets and outlets to the chamber) for all fluids on that path are the same.

[0312] As noted above, the described novel configuration of heat exchanger 700 may be particularly advantageous for use in systems in which the thermally conductive interface 705 and cooling module (or cold plate) of the heat exchanger are arranged on parallel first and second branches of a second cooling circuit. In particular, the first branch of the second cooling circuit may include the described second path 745 through the second chamber (wherein the path passes through or contacts the thermally conductive interface 705 between the first and second chambers). The second branch of the second cooling circuit may include the described first path 745 through the second chamber (which passes through the heat exchanger without receiving heat via the thermally conductive interface 705), the cooling module (or cold plate), and then a third path 755 through the second chamber of the heat exchanger. In this way, the second liquid coolant passing through the second branch of the cooling circuit (passing through the first 745 and third 755 paths through the second chamber of the heat exchanger 700) effectively bypasses one or more thermally conductive mating surfaces 705 in the heat exchanger (on the second path 750 through the second chamber of the heat exchanger). In this way, the thermally conductive mating surfaces 705 in the heat exchanger and the cold plate are arranged in parallel.

[0313] The flow rates of the second liquid coolant through each of the first path 745, second path 750, and third path 755 through the second chamber of the heat exchanger 700 may be different. The relative flow rates of the second liquid coolant through each path (or the percentage of the total volume of the liquid coolant passing through the chamber) may be selected to balance or adjust the cooling power at the thermally conductive interface 705 (which is cooling the first liquid coolant in the cooling circuit) compared to the cooling power at the cooling module or cold plate. For example, the flow rates of the second liquid coolant through each path may be selected to balance or adjust the cooling power at the thermally conductive interface 705 (which is cooling the first liquid coolant in the cooling circuit) compared to the cooling power at the cooling module or cold plate. By increasing the relative flow rate through the second path 750 through the second chamber, a greater volume of the second liquid coolant is routed through the thermally conductive interface 705 than through the cooling module. This provides a greater capacity for heat to be absorbed from the first liquid coolant into the second liquid coolant than from the second electronic device through the cooling module.

[0314] The relative flow rates of the second liquid coolant through each of the first and second paths 745 and 750 can be adjusted by controlling the relative fluid pressure gradient (or pressure drop) across each of the inlet 725, 730 and outlet 735, 740 ports. The pressure gradient, in turn, can be controlled by changing the size of the apertures or openings in the inlet or outlet ports contributing to each of the paths. For example, adjusting the diameter of the nozzle or the size of the aperture in the orifice plate at the outlet 735 to the first path 745 results in a change in the relative flow rates through the cooling module. Alternatively, the flow can be controlled by changing the relative diameters of the inlet and outlet conduits between the heat exchanger and the cooling module.

[0315] In one example, the fluid pressure gradient at the exhaust port 735 contributing to the first path 745 through the second chamber of the heat exchanger may be lower than the fluid pressure gradient at the exhaust port 740 contributing to the second path 750. This results in a lower flow rate through the first path 745 (and thus, in the example above, the inlet and outlet conduits between the heat exchanger and the cooling module) compared to the second path 750.

[0316] In certain configurations of the system where the thermally conductive interface 705 in the heat exchanger and the cooling module (or cold plate) are arranged in parallel first and second branches of the second cooling circuit, the first path 745 (in the branch of the second cooling circuit with the cooling module) may have a flow rate that is 50% or less of the flow rate through the second path 750 (in the branch of the second cooling circuit with the thermally conductive interface 705). In yet a further example, the first path 745 may have a flow rate that is 35% or less than the flow rate through the second path 750. This latter example may be achieved by increasing the flow rate through the common inlet In compared to about 75% or more through the second path 750 (and the second branch of the second cooling circuit). 2A+2B and then passes through first path 745 (and the first branch of the second cooling circuit). The flow rate through each path can also be considered a portion of the total flow rate through the second chamber, and thus, in a given example, first path 745 may have a flow rate of 25% or less of the total flow rate of the second cooling liquid through the second chamber.

[0317] Setting or selecting a flow rate can be beneficial when the heat generated by a first electronic device or devices in contact with the first dielectric coolant is greater than the heat generated by a second electronic device to which the cooling module is coupled. As described above, the balance of coolant passing through the heat exchanger to the cooling module can be controlled by controlling the pressure drop or pressure gradient at the inlet and outlet ports (perhaps using different diameter nozzles, connectors, or openings in the orifice plate at the exit of one path through the chamber).

[0318] 19A and 19B show an example configuration of an electronics module with a hybrid cooling system including two cooperating circulation loops of liquid coolant as described above with reference to FIGS. 1A and 1B, 2A and 2B, and 3A and 3B. The example of FIGS. 19A and 19B shows a system in which the thermally conductive mating surfaces of a heat exchanger and a cooling module (or cold plate) are disposed on respective parallel first and second branches of a second cooling circuit. The system of FIGS. 19A and 19B incorporates a heat exchanger with first and second paths through a second chamber, as described above.

[0319] The electronic module of Figures 19A and 19B shares common features with the examples of Figures 1A and 1B, 2A and 2B, and 3A and 3B described above. In particular, the electronic module 10 of Figures 19A and 19B also comprises a first electronic device 12, a first cooling module 14 and a second cooling module 16 (coupled to respective second and third electronic devices, not shown), and a heat exchanger 318. Here, however, the heat exchanger 318 is of the type described with reference to, for example, Figures 16, 17, or 18.

[0320] The configuration of the first cooling circulation device 20 in the example of Figures 19A and 19B is substantially the same as the configuration described above with respect to Figures 3A and 3B. However, the configuration of the second cooling circulation device 22 is different compared to each of the above-described examples. In particular, in the example of Figures 19A and 19B, upon entering the electronic module 10, the second cooling liquid is routed directly to the heat exchanger 318. The flow of the second liquid coolant to the heat exchanger 318 is split to pass through two paths within the second chamber of the heat exchanger (as described above with reference to Figures 16-18). Only one of the paths through the second chamber of the heat exchanger 318 is in contact with the thermally conductive interface through which heat is transferred from the first liquid coolant to the second liquid coolant.

[0321] 19A and 19B, when the system is in use, the second liquid coolant enters the electronics module 10 through a first inlet in the housing of the electronics module 10 and directly into a first inlet 310 to a second chamber in the heat exchanger 318, which has first and second paths therethrough. Both the first and second paths through the second chamber receive the second liquid coolant into the second chamber in the heat exchanger 318 via the first inlet 310.

[0322] Once in the heat exchanger 318, a first path through the second chamber of the heat exchanger directs a first portion of the second liquid coolant directly to a first outlet 315 from the second chamber of the heat exchanger 318. The first path does not pass through a thermally conductive interface with the first chamber, and the first portion of the second liquid coolant passing along the first path does not receive transferred heat through the thermally conductive interface to form the first liquid coolant.

[0323] A second path through the heat exchanger 318 conducts a second portion of the second liquid coolant across a thermally conductive interface with the first chamber. In this manner, the second portion of the second liquid coolant receives heat transferred from the first liquid coolant in the first chamber of the heat exchanger 318 via the thermally conductive interface. A second path through the heat exchanger 318 conducts the second portion of the second liquid coolant from the second chamber of the heat exchanger 318 to a second outlet 320.

[0324] A first portion of the second liquid coolant passes through the second chamber of the heat exchanger 318 via a first path and exits the second chamber 315 through a first outlet, and is sent to the first and second cooling modules 14, 16 (coupled to the second and third electronic devices, respectively). Here, heat is transferred to the first portion of the second liquid coolant through the thermal interface of each cooling module 14, 16. The first portion of the second liquid coolant is then directed on a third path through the second chamber of the heat exchanger 318 to the second inlet 325 to the second chamber of the heat exchanger 318. The third path does not pass through the thermally conductive interface, as described above with reference to FIGS. 16-18 . In the third path, the first portion of the second liquid coolant rejoins the first portion and exits the heat exchanger from the second chamber of the heat exchanger 318 at the second outlet 320, where it mixes and is mixed with the first portion.

[0325] In this manner, it will be understood that splitting the second liquid coolant to pass through either the first path or the second path through the second chamber of the heat exchanger 318 means splitting the second cooling circuit into two separate branches arranged in parallel. The first branch of the second cooling circuit connects the first cooling module 14 and the second cooling module 15. The second branch of the second cooling circuit is routed to the coolant tank 16, then rejoins the second branch on a third path back through the body of the heat exchanger 318 and is directed out of the heat exchanger 318 to a common discharge 320. The second branch of the second cooling circuit passes through the thermally conductive interface of the heat exchanger 318 (which remains entirely within the heat exchanger 318) and rejoins the first branch before leaving the heat exchanger 318 at a common discharge 320.

[0326] 3A and 3B, in the arrangement of the second cooling circuit 22 of FIGS. 19A and 19B, a portion of the second liquid coolant receives heat from the second and third electronic devices (via the cooling modules 14, 16) separate from a portion that receives heat from the first liquid coolant in the heat exchanger 318. The flow of the second liquid coolant through each branch can be carefully controlled to balance the cooling performance of the cooling modules 14, 16 relative to the heat exchanger 318. For example, the relative flow rates through each of the first and second branches can be adjusted to provide greater cooling power at either the cooling modules 14, 16 or the thermally conductive interface within the heat exchanger 318.

[0327] The electronic module 10 according to Figure 19A is connected to an external cooling system via the same rack 30 as the external cooling system described above with respect to Figures 1A, 2A, and 3A. The electronic module according to Figure 19B is connected to an external cooling system via the same rack 30 as the external cooling system described above with respect to Figures 1B, 2B, and 3B.

[0328] 19A and 19B, the first cooling circulation device 20 may have the same features and advantages as those described above with respect to the system discussed with reference to FIGS. 1A-3B. In particular, the first cooling circulation device 20 may provide immersion cooling, and the first liquid coolant is a dielectric. As described above, the liquid level of the first liquid coolant may be such that, when the system is in use, the first liquid coolant is not in direct contact with the first cooling module 14 and the second cooling module 16, but is at least partially submerged in the first electronic device 12.

[0329] Specific implementations of the systems discussed in Figures 19A and 19B are described in more detail below.

[0330] Referring to FIG. 20A, a specific implementation of the example electronic module 100 described above with reference to FIGS. 19A and 17B (where the thermally conductive mating surfaces of the cooling module and heat exchanger are arranged on parallel branches within a second cooling circuit) is shown. The electronic module may be a module or a server blade, with appropriate dimensions and external connectors to fit within a typical server rack (not shown). The same electronic module 100 is shown in FIGS. 20B and 20C, each depicting a different perspective view of the module. A close-up image of the heat exchanger ports within the system is shown in FIG. 22.

[0331] The electronic module has an outer housing or enclosure 110 that has a base, walls, and a lid, and may be hermetically sealed. Multiple electronic devices (or heat-generating components) are mounted within the housing. In some cases, the components may be mounted on a printed circuit board (PCB) 120 that may be connected to the base, lid, or walls of the housing. The described system is intended to remove heat generated by the electronic devices from within the electronic module.

[0332] The first cooling circuit (or first cooling loop) is used to cool a specific electronic device among the multiple electronic devices mounted in the electronic module. The second cooling circuit (or second cooling loop) is used to cool other heat-generating components. For example, the second cooling circuit may be provided with a greater cooling power and thus may be used to cool a specific component that generates a greater amount of heat than the component cooled by the first cooling circuit. The second cooling circuit may also cool the heat circulating within the first cooling circuit. It is used to cool the first liquid coolant.

[0333] In the example depicted in Figures 20A, 20B, and 20C, the electronics module has a first cooling circuit (or first cooling loop) that provides immersion cooling. The first cooling circuit is contained entirely within the housing 110 of the electronics module. In particular, a first liquid coolant is contained within the sealable housing of the electronics module, and several components 120 to be cooled are at least partially immersed in the first liquid coolant. The first liquid coolant is contained within the volume of the housing 110 of the electronics module and can be thought of as a reservoir of the first liquid coolant.

[0334] First liquid coolant from a first liquid coolant reservoir is collected or received at pump inlet 190. Pump inlet 190 may be shaped to improve the flow of liquid coolant toward pump 185. Pump 185 moves the first liquid coolant through a first cooling circulation system (or first cooling loop). The first liquid coolant passes through pump 185 and travels through pipe 195 into heat exchanger 570. The heat exchanger has the configuration discussed above with reference to FIGS. 16-18 . The first cooling liquid enters a first chamber in heat exchanger 570 via inlet 505, which is separated from a second chamber by a thermally conductive interface. Heat retained in the first cooling fluid may be transferred through the thermally conductive interface to a second cooling fluid, which also passes through heat exchanger 570 as described below. In this manner, the first liquid coolant is cooled as it passes through the heat exchanger 570. As will be appreciated, the first liquid coolant entering the heat exchanger 570 is at a higher temperature than the first liquid coolant exiting the heat exchanger 570.

[0335] In the example of Figures 20A, 20B, and 20C, a pipe 200 is connected to the heat exchanger 170 to carry a first cooling fluid that exits the heat exchanger 170 via outlet 510. At the distal end of the pipe 200 are one or more outlets or nozzles 205a, 205b. In the example of Figures 20A, 20B, and 20C, outlet or nozzle 205a forms an inlet to weirs 202a, 202b, respectively. The weirs act as heat sinks and are part of the first cooling circuit. Weirs are described in more detail above with respect to Figures 12A-14B. However, the first cooling circuit can be constructed without the use of the weir heat sinks described above. For example, the nozzle may be positioned to distribute the first liquid coolant exiting the heat exchanger near the first electronic device, or to direct the first liquid coolant through a reservoir of the first liquid coolant in a housing or chassis (in which the first electronic device is at least partially immersed) toward the pump inlet 190.

[0336] The first cooling liquid exits outlets or nozzles 205a, 205b and passes through weirs 202a, 202b (if used) until it collects in a reservoir of first liquid coolant contained within the volume of housing 110 of electronic module 100. In this manner, the cooler first liquid coolant that has passed through heat exchanger 570 may be reintroduced into the first liquid coolant tank or reservoir within housing 110 and cool any electronic components partially immersed in the reservoir. Specifically, the cooled first liquid coolant will absorb heat from the surfaces of electronic device 120 (including the first electronic device with which it is in contact). Eventually, the first liquid coolant is recollected at pump inlet 190, thereby completing its flow through the first cooling circuit (or first cooling loop).

[0337] 20A, 20B, and 20C also depict a second cooling circulation system. The second cooling circulation system incorporates one or more cooling modules or cold plates 125a, 125b, each mounted to one or more electronic devices. Ideally, the electronic devices require higher performance cooling. The cold plates 125a, 125b are modules or chambers through which a second liquid coolant (such as water) can be passed. Heat is transferred to a given electronic device. Heat can be transferred from the electronic devices 130a, 130b to the second liquid coolant within the cold plates by conduction through the mounting surfaces of the cold plates coupled to the electronic devices 130a, 130b. The cold plates 125a, 125b of the second cooling circulation device are discussed in more detail above with respect to Figures 10A, 10B, and 10C. Although the second cooling circulation device of Figures 20A, 20B, and 20C connects two cold plates in parallel, they could also be connected in series, for example.

[0338] 20A, 20B, and 20C, an inlet 145 in a wall of the electronics module housing 110 directly connects to a first heat exchanger second chamber inlet 515, the heat exchanger being disposed within the electronics module housing 110. Specifically, the inlet 145 directly connects to a second chamber inlet 515 of a heat exchanger 570. The inlet 145 includes a connector, which may be any suitable type of connector, including a quick-disconnect connector. A second liquid coolant is received within the electronics module via the inlet 145. The inlet 145 and the first heat exchanger second chamber inlet 515 may be one piece or integral.

[0339] As discussed above with reference to Figures 16-18, the heat exchanger in the systems of Figures 20A, 20B, and 20C includes at least two paths through the second chamber, and here includes three paths through the second chamber. In the first branch of the second cooling circuit, a first portion of the second liquid coolant passes directly through the body of the heat exchanger 570 via the first path and proceeds to the second chamber outlet 520 of the first heat exchanger. The first inlet conduit 135 is connected to the second chamber outlet 520 of the first heat exchanger for transporting the first portion of the second liquid coolant to the further inlet manifold 150. The second and third inlet conduits 140a, 140b are connected to the further inlet manifold. The second and third inlet conduits 140a, 140b are each connected to a respective cold plate 125a, 125b. In this manner, a first portion of the second cooling fluid can be delivered in parallel to each of the cold plates 125a, 125b within the electronic module, and the second liquid coolant is then passed through the cold plates as described above with respect to Figures 10A, 10B, and 10C.

[0340] The exhaust conduits 155a, 155b are connected to each of the respective cold plates 125a, 125b. The exhaust conduits 155a, 155b receive, in parallel, a first portion of the second liquid coolant exiting each of the cold plates 125a, 125b. The exhaust conduits 155a, 155b are connected to a further exhaust manifold 160, which is connected to an exhaust conduit 165. The exhaust conduit 165 directs the first portion of the second liquid coolant to a second chamber inlet 525 of a second heat exchanger disposed in the housing of the heat exchanger 570. The first portion of the second liquid coolant is then directed on a third path through the heat exchanger 570. As described below, the first portion of the second liquid coolant eventually rejoins the second portion of the second liquid coolant.

[0341] In the second branch of the second cooling circuit, a second portion of the second liquid coolant passes through the second chamber of the heat exchanger 570 via a second path. The second path passes through a thermally conductive interface between the first and second chambers of the heat exchanger 570. In this manner, the second portion of the second liquid coolant contacts the thermally conductive interface and receives heat transferred from the first liquid coolant through the thermally conductive interface. After passing through the thermally conductive interface, the second path merges with a third path through the second chamber of the heat exchanger 570. Thus, the first and second portions of the second liquid coolant (and the first and second branches of the second cooling circuit) reunite.

[0342] After the first and second branches of the second cooling circuit recombine in the heat exchanger 570, the second liquid coolant exits the heat exchanger 570 via the second chamber outlet 530 of the second heat exchanger. This routes the second liquid coolant directly to the outlet 180 in the wall of the housing of the electronics module. The outlet 180 includes a connector, which may be any suitable type of connector, including a quick disconnect connector. The outlets 530 may be the same single unit.

[0343] Although not shown in Figures 20A, 20B, and 20C, inlet 145 and outlet 180 may each be connected to a cooling system or a second liquid coolant supply (e.g., by additional piping connected to inlet 145 and outlet 180, if desired). This is discussed in more detail below with respect to Figures 22A and 22B.

[0344] Advantageously, the system described with reference to Figures 20A, 20B, and 20C has all the advantages of the second circulation system with first and second parallel branches, as described above with reference to Figures 8A, 8B, and 8C. For example, the described system allows both cold plates 125a, 125b to exchange heat through the thermally conductive interface at the heat exchanger 570 and benefit from the lowest temperature second liquid coolant. Furthermore, this configuration allows for balancing the flow rate (and cooling performance) at the thermally conductive interface of the heat exchanger 570 compared to the cold plates 125a, 125b. Such balancing may be achieved, for example, by varying the opening size of each of the second chamber outlets 505, 530 of the first and second heat exchangers. Furthermore, compared to the system configurations shown in FIGS. 8A, 8B, and 8C, the system of FIGS. 20A, 20B, and 20C reduces the number and length of conduits and connectors joining the various components of the design (e.g., so that the inlet 145 and outlet 180 to the housing directly connect to the inlet 515 and outlet 530 at the heat exchanger). This significantly reduces the space required to connect the heat exchanger 570 inside the electronics module, reducing the complexity of the connections and the likelihood of leaks between them. Therefore, this design is more space-efficient and less prone to failure. Furthermore, the described system allows for a modular design of the electronics module housing 110 with common inlet and outlet ports.

[0345] 22A and 22B show schematic diagrams of the first and second cooling circulation devices of FIGS. 20A, 20B, and 20C when the electronic module 100 is connected in a rack 400. The arrangement of the first and second cooling circulation devices within the electronic module is the same for both examples of FIGS. 22A and 22B. However, the device for providing the low-temperature second liquid coolant to the electronic module is different in the two examples of FIGS. 22A and 22B. In particular, the external cooling system for providing the second liquid coolant in the example of FIG. 22A is the same as the external cooling system described above with reference to FIG. 1A (i.e., heat transfer from the second liquid coolant to a third coolant medium via an additional heat exchanger 34). In the example of FIG. 22B, the external cooling system for providing the second liquid coolant is the same as the external cooling system described above with reference to FIG. 1B (i.e., a supply of second liquid coolant from a facility-level supply, such as a chilled water supply).

[0346] 22A and 22B, a first cooling circulation system is shown having a pump inlet 190, a pump 185, a heat exchanger 570, and a weir 202 for circulating a first liquid coolant within the housing of the electronic module 100. Figures 22A and 22B further show a second cooling circulation apparatus comprising first and second cooling modules (or cold plates) 125a, 125b, and a heat exchanger 570.

[0347] During use, the second liquid coolant is received by the electronics module through the inlet 145 and is routed directly to the second chamber of the heat exchanger 570 via the first heat exchanger's second chamber inlet 505. Within the heat exchanger 570, the second liquid coolant is split into two branches. The first branch passes the second liquid coolant out of the heat exchanger 570 to the first heat exchanger's second chamber outlet 515 and directly to two cooling modules (or cold plates) 125a, 125b arranged in parallel. After passing through the cooling modules (or cold plates) 125a, 125b, the second liquid coolant from the first branch re-enters the second chamber of the heat exchanger 570 through the second heat exchanger's second chamber inlet 520.

[0348] During use, the second branch of the second cooling circuit passes along a path through the second chamber of the heat exchanger 570 in contact with the thermally conductive interface. Heat may be received from the first liquid coolant (flowing through the first chamber of the heat exchanger 570) via the thermally conductive interface. The second branch of the second cooling circuit then rejoins the first branch in the second chamber of the heat exchanger 570 before exiting the heat exchanger 570. The second cooling liquid then exits the heat exchanger 570 via a common second outlet 530 from the second chamber of the heat exchanger and passes directly through an outlet 180 in the wall of the electronic module.

[0349] The inlet 145 and outlet 180 of the electronic module may be connected to an inlet 405 or outlet 410 manifold, respectively, in the server rack 400 in which the electronic module 100 is mounted. The inlet 145 and outlet 180 may be connected to the inlet manifold 405 and outlet manifold 410 of the server rack 400 via quick disconnect connectors.

[0350] While specific heat exchanger configurations have been discussed with reference to Figures 16-18, it will be understood that other heat exchanger configurations are possible in which one of the first or second chambers of the heat exchanger has two or more inlets and / or outlets. In each case, at least two paths are disposed through the same chamber, which has two or more inlets and / or two or more outlets. In each case, two or more of the at least two paths share at least one common inlet and / or outlet. However, at least one of the paths includes a different combination of inlets and / or outlets than another of the paths. In this way, although the paths are all fluidly connected, each separate path through a given chamber of the heat exchanger provides a different flow path between different combinations of connectors. Despite the different paths, the relative flow rates can be adjusted to allow different volumes of liquid coolant to pass through each separate path.

[0351] 23(a), 23(b), and 23(c) show just a few of the various different pathways that can be formed through a single chamber (such as the second chamber) of a heat exchanger according to the previously described configuration. Only some pathways are positioned in contact with the thermally conductive mating surfaces for heat exchange with liquid coolant flowing in a separate chamber (where flow through that separate chamber is not shown in FIGS. 23(a), 23(b), or 23(c). FIG. 23(a) shows a chamber with two pathways, each with a common inlet but separate outlets. FIG. 23(b) shows a further example of a chamber with two pathways, each with a common inlet but separate outlets. FIG. 23(c) shows an example of a chamber with three pathways, where the first pathway has a common inlet and a separate outlet with the second pathway, and the third pathway has a separate inlet and a common outlet with the second pathway.

[0352] Several combinations of the various described embodiments may be envisioned by those skilled in the art. All features disclosed herein may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. In particular, preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Similarly, features described in non-essential combinations may be used separately (not in combination).

[0353] Each feature disclosed in this specification, unless expressly stated otherwise, may be replaced by alternative features serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.

[0354] As used in this specification, including the claims, unless the context otherwise dictates, the singular forms of terms herein are to be construed as including the plural forms and the context permits. and vice versa. For example, unless the context dictates otherwise, references herein to singular forms such as "a" or "an" in the claims mean "one or more." Throughout the description and claims of this disclosure, the words "comprise," "including," "having," and "contain," as well as variations of these words such as "comprising" and "comprises" or similar, mean that the recited features include the additional features that follow, and are not intended to exclude the presence of other elements (and are not intended to do so).

[0355] The use of any and all examples or exemplary language (such as "for example," "for example," "for example," and similar language) provided herein is intended merely to better describe the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise asserted. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

[0356] Any steps described herein may be performed in any order, or simultaneously, unless otherwise specified or unless the context requires otherwise. Furthermore, if a step is described as being performed after a step, this does not exclude intervening steps from being performed.

Claims

1. 1. A system for cooling a plurality of electronic devices, the electronic devices being contained within an electronic module housing, the system comprising: a first cooling circulation apparatus configured to circulate a first liquid coolant between a first electronic device of the plurality of electronic devices and a heat exchanger, the first electronic device being positioned to be thermally coupled to the first liquid coolant such that heat generated in the first electronic device is transferred to the first liquid coolant when the system is in use; and a second cooling circulation system configured to cause a second liquid coolant to flow through the heat exchanger and to cause the second liquid coolant to flow through a cooling module thermally coupled to a second electronic device of the plurality of electronic devices, wherein when the system is in use, heat generated by the second electronic device is transferred to the second liquid coolant through a surface of the cooling module; The system, wherein the first cooling circulation device and the second cooling circulation device are thermally coupled via the heat exchanger such that the heat exchanger is configured to transfer heat from the first liquid coolant to the second liquid coolant.

2. 2. The system of claim 1, wherein the second cooling circulation device is configured to cause the second liquid coolant to flow through the heat exchanger and from the heat exchanger through the cooling module when the system is in use.

3. The system of claim 1 , wherein the second cooling circulation device is configured to flow the second liquid coolant through the cooling module and from the cooling module through the heat exchanger.

4. 2. The system of claim 1, wherein the heat exchanger and the cooling module are arranged on parallel branches of the second cooling circuit such that the second cooling circuit is configured to flow the second liquid coolant through the heat exchanger and flow the second liquid coolant through the cooling module in parallel.

5. 10. The system of claim 1, wherein the housing is configured to store the first liquid coolant, and wherein, when the system is in use, the first electronic device is at least partially immersed in the first liquid coolant stored within the housing.

6. 10. The system of claim 9, wherein the housing is configured to store a volume of a first liquid coolant that fills the housing to a liquid level when the system is in use, the cooling module is positioned within the housing such that it is above the liquid level of the first liquid coolant, and the first electronic device is positioned within the housing such that it is at least partially immersed in the first liquid coolant stored within the housing.

7. 10. The system of claim 9, wherein the heat exchanger comprises at least a first chamber and a second chamber separated from one another by a thermally conductive interface, the heat exchanger configured for flow of the first liquid coolant through at least the first chamber and for flow of the second liquid coolant through at least the second chamber such that heat is transferred from the first liquid coolant to the second liquid coolant through the thermally conductive interface.

8. 10. A system according to any one of the preceding claims, wherein the heat exchanger is arranged within the housing of the electronic module.

9. The first cooling circulation device further comprises a weir, the weir comprising: a base and a retaining wall extending from the base, the base and retaining wall defining a volume for storing a portion of the first liquid coolant; a weir inlet through which the first liquid coolant enters the volume; 10. The system of claim 9, wherein sufficient flow of the first liquid coolant into the volume through the weir inlet causes the first liquid coolant to overflow the retaining wall and collect with first liquid coolant stored within the housing of the electronic module and external to the weir.

10. The system of claim 9 , wherein the weir inlet further comprises a nozzle arrangement for directing the first liquid coolant flowing into the volume.

11. 11. The system of claim 9 or 10, wherein the weir further comprises a protrusion extending from the base and / or retaining wall within the volume of the weir.

12. 12. The system of claim 9, wherein the dam is coupled to a surface of the first electronic device to act as a heat sink, or the first electronic device is positioned within the volume of the dam.

13. The first cooling circulation device comprises:

10. The system of any one of the preceding claims, further comprising a pump configured to circulate the first liquid coolant around the first cooling circulation device.

14. 14. The system of claim 13, wherein the first cooling circulation device further comprises a pump inlet positioned to receive a first liquid coolant housed within the housing of the electronic module and external to the weir.

15. The cooling module is a cold plate comprising a cold plate housing, a surface of the cold plate housing arranged to provide a thermal interface for cooling the second electronic device thermally coupled to the cold plate housing; and at least one channel within the cold plate housing and proximate to the surface of the cold plate housing, the at least one channel being arranged such that the second liquid coolant flows through the at least one channel such that heat received from the second electronic device through the surface of the cold plate housing is transferred to the second liquid coolant.

16. 1. A method for cooling a plurality of electronic devices, the electronic devices being contained within a housing of an electronic module, the system comprising: circulating a first liquid coolant through a first cooling circulation apparatus, the first liquid coolant including circulating the first liquid coolant between a first electronic device of the plurality of electronic devices and a heat exchanger, the first electronic device being positioned to be thermally coupled to the first liquid coolant such that heat generated at the first electronic device is transferred to the first liquid coolant; transporting a second liquid coolant around a second cooling circulation apparatus, the second liquid coolant flowing through the heat exchanger and the second liquid coolant flowing through a cooling module thermally coupled to a second electronic device of the plurality of electronic devices, wherein heat generated by the second electronic device is transferred to the second liquid coolant through a surface of the cooling module; The first cooling circulation device and the second cooling circulation device are thermally coupled via the heat exchanger such that heat is transferred from the first liquid coolant to the second liquid coolant via the heat exchanger.

17. 17. The method of claim 16, wherein transporting the second liquid coolant around the second cooling circuit comprises flowing the second liquid coolant through the heat exchanger and from the heat exchanger through the cooling module when the system is in use.

18. 17. The method of claim 16, wherein transporting the second liquid coolant around the second cooling circuit comprises flowing the second liquid coolant through the cooling module and from the cooling module through the heat exchanger.

19. 17. The method of claim 16, wherein the heat exchanger and the cooling module are disposed on parallel branches of the second cooling circuit, and transporting the second liquid coolant around the second cooling circuit comprises flowing the second liquid coolant through the heat exchanger and flowing the second liquid coolant through the cooling module in parallel.

20. 20. The method of any one of claims 16 to 19, wherein the housing is configured to store the first liquid coolant, and the first electronic device is at least partially immersed in the first liquid coolant stored within the housing.

21. 21. The method of claim 16, wherein the housing is configured to store a volume of a first coolant that fills the housing to a liquid level, the cooling module is disposed within the housing such that it is above the liquid level of the first liquid coolant, and the first electronic device is disposed within the housing such that it is at least partially immersed in the first liquid coolant stored within the housing.

22. 1. A system for cooling a plurality of electronic devices, the electronic devices being contained within an electronic module housing, the system comprising: a first cooling circulation apparatus configured to circulate a first liquid coolant between a first electronic device of the plurality of electronic devices and a first chamber of a heat exchanger, the first electronic device being positioned to be thermally coupled to the first liquid coolant such that heat generated in the first electronic device is transferred to the first liquid coolant when the system is in use; a second cooling circulation apparatus configured to cause a second liquid coolant to flow through a second chamber of the heat exchanger and to cause the second liquid coolant to flow through a cooling module thermally coupled to a second electronic device of the plurality of electronic devices, wherein when the system is in use, heat generated by the second electronic device is transferred to the second liquid coolant through a surface of the cooling module; The first and second cooling circulation devices are configured to couple the heat exchanger such that, in use, the heat exchanger is configured to transfer heat from the first liquid coolant in the first chamber to the second liquid coolant in the second chamber via the thermally conductive interface. the first chamber and the second chamber of the exchanger are thermally coupled via a thermally conductive interface separating the first chamber and the second chamber of the exchanger.

23. 23. The system of claim 22, wherein the second cooling circulation device is configured to cause the second liquid coolant to flow through the second chamber of the heat exchanger and from the second chamber of the heat exchanger through the cooling module when the system is in use.

24. 23. The system of claim 22, wherein the second cooling circulation device is configured to cause the second liquid coolant to flow through and from the cooling module through the second chamber of the heat exchanger when the system is in use.

25. 23. The system of claim 22, wherein the thermally conductive interface on the cooling module and the heat exchanger is arranged on parallel first and second branches of the second cooling circulation device, and the second cooling circulation device is configured to flow the second liquid coolant through the first branch of the second cooling circulation device that includes the cooling module and to flow the second liquid coolant through the second branch of the second cooling circulation device that includes the thermally conductive interface on the heat exchanger.

26. 26. The system of claim 25, wherein the heat exchanger comprises a plurality of paths through the second chamber, the first branch of the second cooling circulation device is configured to cause the second liquid coolant to flow through a first path through the second chamber of the heat exchanger and through the cooling module, and the second branch of the second cooling circulation device is configured to cause the second liquid coolant to flow through a second path through the second chamber of the heat exchanger and across the thermally conductive interface.

27. 27. The system of claim 26, wherein the first path through the second chamber of the heat exchanger does not flow across the thermally conductive interface.

28. 28. The system of claim 22, wherein the housing is configured to store the first liquid coolant, and wherein, when the system is in use, the first electronic device is at least partially immersed in the first liquid coolant stored within the housing.

29. 29. The system of claim 22, wherein the housing is configured to store a volume of a first liquid coolant that fills the housing to a liquid level when the system is in use, the cooling module is positioned within the housing such that it is above the liquid level of the first liquid coolant, and the first electronic device is positioned within the housing such that it is at least partially immersed in the first liquid coolant stored within the housing.

30. The first cooling circulation device further comprises a weir, the weir comprising: a base and a retaining wall extending from the base, the base and retaining wall defining a volume for storing a portion of the first liquid coolant; a weir inlet through which the first liquid coolant enters the volume; 30. The system of any one of claims 22-29, wherein sufficient flow of the first liquid coolant into the volume through the weir inlet causes the first liquid coolant to overflow the retaining wall and collect with first liquid coolant stored within the housing of the electronic module and external to the weir.

31. 31. The system of claim 30, wherein the weir inlet further comprises a nozzle arrangement for directing the first liquid coolant flowing into the volume.

32. 32. The system of claim 30 or 31, wherein the weir further comprises a protrusion extending from the base and / or retaining wall within the volume of the weir.

33. 33. The system of any one of claims 30 to 32, wherein the dam is coupled to a surface of the first electronic device to act as a heat sink, or the first electronic device is positioned within the volume of the dam.

34. The first cooling circulation device comprises: The system of any one of claims 22 to 33, further comprising a pump configured to circulate the first liquid coolant around the first cooling circulation device.

35. 35. The system of claim 34, wherein the first cooling circulation device further comprises a pump inlet positioned to receive a first liquid coolant housed within the housing of the electronic module and external to the weir.

36. The cooling module is a cold plate comprising a cold plate housing, a surface of the cold plate housing arranged to provide a thermal interface for cooling the second electronic device thermally coupled to the cold plate housing; and at least one channel within the cold plate housing and proximate to the surface of the cold plate housing, the at least one channel being positioned such that the second liquid coolant flows through the at least one channel such that heat received from the second electronic device through the surface of the cold plate housing is transferred to the second liquid coolant.

37. The system of any one of claims 22 to 36, wherein the heat exchanger is located within the housing of the electronic module.

38. 38. The system of any one of claims 22 to 37, wherein the heat exchanger comprises at least the first chamber and the second chamber separated from one another by the thermally conductive interface, the heat exchanger configured for flow of the first liquid coolant through at least the first chamber and flow of the second liquid coolant through at least the second chamber such that heat is transferred from the first liquid coolant to the second liquid coolant through the thermally conductive interface.

39. The system of any one of claims 22 to 38, wherein the second chamber of the heat exchanger further comprises two or more inlets and / or outlets.

40. 40. The system of claim 39 when dependent on claim 26 or 27, wherein at least one of the two or more inlets and / or outlets is common to the first and second paths through the second chamber.

41. 41. The system of claim 40, wherein the first pathway has an inlet or outlet that is common with the second pathway and another inlet or outlet that is not common with the second pathway.

42. 42. The system of claim 41, wherein the relative flow rates of the second liquid coolant through the first path and the second path are determined by a pressure gradient across the inlet or outlet in the first path that is not common to the second path.

43. 43. The system of claim 42, wherein the pressure gradient across the inlet or outlet in the first path that is not common to the second path is determined by the size of an aperture in the inlet or outlet in the first path that is not common to the second path, the aperture being an opening through which the second liquid coolant flows into or out of the second chamber.

44. 44. The system of claim 26, claim 27, or any one of claims 39 to 43 when dependent on claim 26 or claim 27, wherein a flow rate of the second liquid coolant through the first path is less than a flow rate of the second liquid coolant through the second path.

45. 45. The system of claim 44, wherein a flow rate of the second liquid coolant through the first path is less than or equal to 50% of a flow rate of the second liquid coolant through the second path.

46. 45. The system of claim 44, wherein a flow rate of the second liquid coolant through the first path is no more than 35% of a flow rate of the second liquid coolant through the second path.

47. 1. A method for cooling a plurality of electronic devices, the electronic devices being contained within a housing of an electronic module, the system comprising: circulating a first liquid coolant through a first cooling circulation apparatus, the first liquid coolant including circulating the first liquid coolant between a first electronic device of the plurality of electronic devices and a first chamber of a heat exchanger, the first electronic device being positioned to be thermally coupled to the first liquid coolant such that heat generated at the first electronic device is transferred to the first liquid coolant; transporting a second liquid coolant around a second cooling circulation apparatus, the second liquid coolant flowing through a second chamber of the heat exchanger and the second liquid coolant flowing through a cooling module thermally coupled to a second electronic device of the plurality of electronic devices, wherein heat generated by the second electronic device is transferred to the second liquid coolant through a surface of the cooling module; the first cooling circulation device and the second cooling circulation device are thermally coupled via a thermally conductive interface separating the first and second chambers of the heat exchanger such that heat from the first liquid coolant in the first chamber of the heat exchanger is transferred to the second liquid coolant in the second chamber of the heat exchanger via the thermally conductive interface.

48. 48. The method of claim 47, wherein transporting the second liquid coolant around the second cooling circuit comprises flowing the second liquid coolant through the second chamber of the heat exchanger and from the second chamber of the heat exchanger through the cooling module.

49. 48. The method of claim 47, wherein transporting the second liquid coolant around the second cooling circuit comprises flowing the second liquid coolant through and from the cooling module through the second chamber of the heat exchanger.

50. The thermally conductive mating surfaces of the cooling module and the heat exchanger are disposed on parallel first and second branches of the second cooling circulation device, and the second liquid coolant is introduced into the second cooling circuit.

48. The method of claim 47, wherein transporting the second liquid coolant around a cooling circulation device comprises: flowing the second liquid coolant through the first branch of the second cooling circulation device that comprises the cooling module; and flowing the second liquid coolant through the second branch of the second cooling circulation device that comprises the thermally conductive interface on the heat exchanger.

51. 51. The method of claim 50, wherein the heat exchanger comprises a plurality of paths through the second chamber, and transporting the second liquid coolant around the second cooling circulation device comprises: flowing the second liquid coolant through the first branch of the second cooling circulation device comprising a first path through the second chamber of the heat exchanger and the cooling module; and flowing the second liquid coolant through the second branch of the second cooling circulation device comprising a second path through the second chamber of the heat exchanger across the thermally conductive interface.

52. 52. The method of claim 51, wherein the first path through the second chamber of the heat exchanger does not flow across the thermally conductive interface.

53. 53. The method of any one of claims 47 to 52, wherein the housing is configured to store the first liquid coolant, and the first electronic device is at least partially immersed in the first liquid coolant stored within the housing.

54. 54. The method of any one of claims 47 to 53, wherein the housing is configured to store a volume of a first coolant that fills the housing to a liquid level, the cooling module is positioned within the housing such that it is above the liquid level of the first liquid coolant, and the first electronic device is positioned within the housing such that it is at least partially immersed in the first liquid coolant stored within the housing.

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