Cold plate and system for cooling electronic devices - Patents.com

Abstract

The cold plate is configured to use separate primary and secondary liquid coolants, and defines an interior volume and includes a thermal conductor mounted relative to the electronic device and configured to transfer heat from the electronic device to the interior volume, a coolant inlet for receiving the secondary liquid coolant into the interior volume to receive the transferred heat, and a coolant outlet for the secondary liquid coolant to flow from the interior volume. The thermal conductor is configured to define an exterior receptacle having a volume configured to receive and hold the primary liquid coolant for heat transfer between the primary and secondary liquid coolants. The cold plate may form part of a system for cooling an electronic device.

Description

[Technical field]

[0001] Field of Disclosure The present disclosure relates to a cold plate and a system for cooling an electronic device comprising such a cold plate. [Background technology]

[0002] 2. Background of the Invention Computers, servers, and other devices used in data processing (called information technology or IT) typically include printed circuit boards (PCBs). On these PCBs are small devices called integrated circuits (ICs), which may include central processing units (CPUs), application specific integrated circuits (ASICs), graphic processing units (GPUs), random access memories (RAMs), etc. All of these electronic components or devices generate heat when in use. To maximize the performance of the IT, the heat must be transferred to keep the contents at an optimal temperature. These considerations also apply to other types of electronic devices or systems.

[0003] IT is usually contained within a case, enclosure, or housing. For example, for servers, this enclosure may be called a server chassis. Server chassis typically adhere to several industry standards that specify the height of each chassis, called 1RU (one rack unit) or 1OU (one open unit), also abbreviated as 1U or 1OU. The smaller of the two main standards is 1RU / 1U, which is 44.45mm or 1.75 inches in height. Such units are sometimes called "blade" servers, in terms of shape and style, although such server chassis may not need to slot or plug into a backplane, for example.

[0004] Different server products can utilize multiple RU / OUs at a time for a chassis, for example a 2U chassis uses two rack units. The size of each server chassis is typically kept to a minimum to maximize computing power per server rack (the server rack is the main housing to which the server chassis are added).

[0005] Typically, electronic components or devices used on or in IT are cooled using air. This usually involves some type of heat sink, with fins or the like placed in contact with either the chip surface directly or with a TIM (thermal interface material) between the two components. In addition to the heat sink, each enclosure uses a series of fans to draw air through the enclosure, remove heat from the heat sink, and expel it out of the chassis. This type of heat sink is used in combination with server equipment side cooling, such as air conditioning. This cooling method is not particularly efficient, has high running costs, and uses a large amount of space to manage the air used for cooling.

[0006] This method of cooling IT has been used almost exclusively for mass-produced IT and server equipment. More recently, however, the limitations of cooling devices with air have limited the peak performance of heat-generating chips. As technology halves in size for the same performance every few years (as exemplified by Moore's Law), the heat generated by chips has increased as component footprints have decreased. This has seen an increase in the size and complexity of heat sinks designed for air cooling. The result is often a larger required server chassis size, and therefore less computing power within a single rack.

[0007] As an alternative to air cooling, liquid cooling can be used. Liquid cooling can, in some cases, provide more efficient heat transfer from electronic components or devices and therefore greater cooling power. These liquids include dielectric fluids, mineral oil and water, to name a few. Several existing approaches using liquid cooling are known. For example, WO 2018 / 096362, commonly assigned with this disclosure, describes a submerged liquid cooling approach in which a primary liquid coolant, typically a dielectric liquid, is pumped within a sealed chassis so that it remains inside. A heat exchanger is also within the chassis, transferring heat from the primary liquid coolant to a secondary liquid coolant that flows outside the chassis (which may be shared between multiple chassis) and is typically water or water-based (which is advantageous as it has a high specific heat capacity).

[0008] Building on this, WO 2019 / 048864, also commonly assigned with the present disclosure, describes several types of heat sinks that may be mounted on, around, or adjacent to an electronic device, or on or around which an electronic device may be mounted. The heat sink defines an internal volume for accumulating and retaining a primary liquid coolant adjacent to the electronic device(s). As the primary liquid coolant flows (by pumping and / or convection) within the chassis, it is directed into the internal volume of the heat sink, improving cooling of the electronic device (e.g., an IC or a power supply unit that becomes particularly hot during operation). The primary liquid coolant then flows out of the heat sink internal volume (e.g., by overflow and / or by flowing through holes in the volume) and collects with the remaining primary liquid coolant within the chassis to cool other electronic devices (e.g., other components or ICs mounted on the PCB or otherwise within the chassis). The primary liquid coolant is again cooled by a heat exchanger within the chassis, and heat is transferred to a secondary liquid coolant. In this approach, the height of the primary liquid coolant within the chassis can be kept low, certainly lower than the height of the primary liquid coolant within the heat sink internal volume. This forms the liquid cooling at multiple levels (heights), reducing the amount of liquid coolant required and allowing efficient single-phase (i.e., liquid phase only) cooling of the electronic device. Because primary liquid coolant can be expensive, difficult to contain, and prone to contamination, this approach can provide significant benefits in terms of reduced cost and complexity.

[0009] In a different approach, U.S. Patent No. 7,724,524 describes a hybrid immersion cooling apparatus for computing systems in which a blade server chassis houses the electronic components. A cold plate is coupled to some of the electronic components for cooling, and pipes within the chassis provide coolant to the cold plate from outside the chassis. After passing through the cold plate (or multiple cold plates), the coolant is returned to the outside of the chassis. Another coolant is provided within the chassis, immersing the remaining electronic components and the cold plate. The chassis is made liquid-tight to prevent leakage of this coolant. The immersion coolant is cooled by the coolant flowing through the cold plate. Making the server environment quieter and more energy efficient is identified as an important consideration in this document.

[0010] It would be desirable to provide an improved liquid coolant based system that has high performance and efficiency. Summary of the Invention [Means for solving the problem]

[0011] Disclosure Summary Against this background, there is provided a cold plate according to claim 1 and a system for cooling an electronic device according to claim 8. Further preferred and / or advantageous features are specified in the dependent claims and the remaining disclosure of the present specification. Methods of manufacturing and / or operating cold plates and / or systems for cooling electronic devices having steps corresponding to the structural features described herein are also contemplated.

[0012] A cold plate is provided having an external receptacle. The external receptacle defines a volume that can receive (e.g., through a nozzle), store and / or hold a primary liquid coolant to provide heat transfer between a primary liquid coolant outside the cold plate and a secondary liquid coolant flowing through the cold plate (e.g., in a conventional manner). The primary and secondary liquid coolants are advantageously separate, separate and physically isolated from one another (although thermally coupled). Such an approach can be significantly more efficient than those previously described, increasing the efficiency of the system.

[0013] The primary liquid coolant may be dielectric and / or the secondary liquid coolant may be aqueous. The body of the cold plate is thermally conductive, allowing for heat transfer from the electronic device to which the cold plate is attached or adjacent to which it is attached, to the secondary liquid coolant. The secondary liquid coolant typically flows through a liquid circuit entirely separate from the primary liquid coolant. An external receptacle volume may be defined by a retaining wall formed by or integral with the body of the cold plate, further facilitating heat transfer. The volume is generally closed, except for one side, which is typically open. The open side may be parallel (e.g., opposite) to the mounting surface (typically planar) of the cold plate, such an embodiment may be suitable for horizontal mounting. Alternatively, the open side may be perpendicular (e.g., adjacent) to the mounting surface of the cold plate, which may be suitable for vertical mounting.

[0014] Protrusions (pins and / or fins) may be formed within the volume of the external receptacle. This may facilitate heat transfer between the primary and secondary liquid coolants. Additionally or alternatively, protrusions (pins and / or fins) may be formed within the cold plate. These may facilitate heat transfer more generally, particularly when the protrusions extend entirely (or at least substantially) between an inner surface of the cold plate adjacent the electronic device to be cooled and an opposing inner surface of the cold plate (generally adjacent the volume of the external receptacle).

[0015] The cold plate generally forms part of a system that also includes a chassis housing the electronic devices, and the cold plate is attached to or adjacent to one of the electronic devices for cooling the one of the electronic devices and a primary liquid coolant. The primary liquid coolant flows (e.g., by pumping and / or convection) and is directed through suitable nozzles into the volume of the external receptacle of the cold plate. Thus, the primary liquid coolant can be cooled by contact with the cold plate, and in particular its external receptacle. Multiple such cold plates may be provided, each cooling a different electronic device(s), and these may be connected in series and / or parallel, as discussed below.

[0016] Advantageously, the primary liquid coolant flows out of the volume of the external receptacle (e.g., by overflow) and then at least partially submerges other electronic devices within the chassis. The height of the primary liquid coolant within the chassis outside the heat sink is less than the height retained within the volume of the external receptacle. This creates multiple heights of primary liquid coolant, reducing the amount of primary liquid coolant required without reducing the efficiency of heat transfer. In particular, the system may be configured such that all of the primary liquid coolant flows through the volume of the external receptacle of one or more cold plates.

[0017] The chassis advantageously comprises respective inlets and outlets for secondary liquid coolant to and from the outside of the chassis (e.g., using quick disconnect connectors). Piping may then be provided to transport cold secondary liquid coolant from the inlets to the cold plate and warmed secondary liquid coolant from the cold plate to the outlet. An inlet manifold may be provided between the inlets and the piping, and / or an outlet manifold may be provided between the piping and the outlet. The manifolds may be useful for connecting multiple cold plates in parallel to the same inlets and outlets. Additionally or alternatively, the cold plates may be connected in series. If multiple cold plates are provided, one, some, or all of the cold plates may follow the cold plate design disclosed herein.

[0018] The primary liquid coolant may flow by convection and / or pumping. If a pump is used, a pump manifold may be provided to connect a single pump to multiple cold plates. In an embodiment, multiple pumps may be used. For example, each pump may form part of a respective cold plate. This may be in the form of a micropump, for example.

[0019] The present disclosure may be practiced in a number of ways and preferred embodiments will now be described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a schematic isometric view of the interior of a server chassis according to one embodiment of the present disclosure. [Diagram 2] 2 is a schematic plan view of the inside of the server chassis shown in FIG. [Diagram 3] FIG. 2 is a schematic, isolated isometric view of some of the components within the server chassis shown in FIG. 1. [Figure 4] 2 illustrates a schematic isometric view of a cold plate according to an embodiment of the present disclosure for use in the server chassis shown in FIG. 1; [Diagram 5] FIG. 5 is an exploded view of the cold plate of FIG. 4. [Figure 6] 1 is a schematic cross-sectional view of a cold plate according to an embodiment of the present disclosure. [Figure 7] 1 shows a schematic cross-sectional view of a cold plate according to a simplified or modified embodiment of the present disclosure; [Figure 8] 2 is a schematic isolated isometric view of some of the components within a server chassis in yet another variation of that shown in FIG. 1. [Figure 9] 2 shows a schematic isolated isometric view of a portion of a plurality of cold plates and additional components within a server chassis in yet another variation of that shown in FIG. 1; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Detailed Description of the Preferred Embodiments While the present disclosure generally provides hybrid cold plate and heat sink components for use in multi-stage (single-phase) liquid cooling systems, and particularly for use in cooling computer server blades, those skilled in the art will recognize the applicability of the present technology to cooling other electronic components and devices. A primary liquid coolant circulates within the server chassis (typically by pumping, but convection may be used in addition or instead). A general height of the primary liquid coolant within the chassis is used to cool cooler components within the chassis. The warmer components are cooled by a cold plate that is thermally coupled to the components (specifically attached to the cold plate). The cold plate receives a secondary liquid coolant from outside the chassis. The primary and secondary liquid coolants are isolated from each other in the sense that they are separate, distinct (specifically, the primary liquid coolant is typically not electrically conductive, while the secondary liquid coolant is generally aqueous), and do not directly contact each other. However, the primary liquid coolant is pumped directly onto the cold plate and held against the thermal conductor of the cold plate in a receptacle portion of the cold plate. This holding of the primary liquid coolant against the cold plate body allows for heat transfer between the primary and secondary liquid coolants.

[0022] In this manner, the cold plate of the present disclosure may represent a hybrid between a cold plate (using a water-based coolant) and a heat sink of the type disclosed in WO 2019 / 048864 (using a dielectric coolant). Cold plate technology provides high performance cooling and focuses on cooling the hottest components. However, the approach taken by the present disclosure avoids the need for a cold plate to be directly attached to each component. The cold plate cools the hottest component (e.g., the processor or graphics processing unit, GPU), and the remaining components are cooled using a dielectric coolant.

[0023] In a first generalized aspect, a cold plate may be considered. The cold plate is configured to use isolated (in other words, separate, isolated, or unmixed) primary and secondary liquid coolants. The cold plate comprises a thermal conductor, the thermal conductor defining an interior volume (for receiving the secondary liquid coolant) and configured to attach (e.g., by one or more of shaping and / or dimensioning the thermal conductor and providing mounting points and / or holes) to an electronic device to transfer heat from the electronic device to the interior volume (through the thermal conductor), the cold plate further comprising a coolant inlet for receiving the secondary liquid coolant into the interior volume to receive the transferred heat, and a coolant outlet for the secondary liquid coolant to flow out of the interior volume. The thermal conductor is further configured (e.g., shaped or disposed) to define an external receptacle (i.e., a receptacle that is external to the cold plate body or housing, as opposed to an interior volume within the body). The external receptacle has a volume and is configured to receive and retain a primary liquid coolant for heat transfer between the primary liquid coolant and the secondary liquid coolant. In particular, the volume of the external receptacle is substantially closed (e.g., except for a relatively small hole) on all sides except one side.

[0024] Such an arrangement has significant advantages over existing approaches. A cold plate heat sink hybrid device of such design provides an efficient primary (e.g., dielectric) liquid coolant loop in which heat is transferred in an efficient manner from a flowing primary liquid coolant to a secondary (e.g., water-based or essentially water-containing) liquid coolant. As discussed further below, there are resulting benefits in pressure, space, and power. Further optional and / or preferred features are discussed in a more generalized sense below, but further details of specific embodiments are presented first.

[0025] Referring initially to Figure 1, there is shown a schematic isometric view of the interior of a server chassis 1 according to an embodiment of the present disclosure. In this view, the water-based (secondary) coolant loop is particularly shown. It includes an inlet quick disconnect connector 2, an inlet hose 3, an inlet manifold 4, an inlet plumbing hose 5, a cold plate heat sink hybrid device 6, an outlet plumbing hose 7, an outlet manifold 8, an outlet hose 10, and an outlet quick disconnect connector 11. Other features forming part of this embodiment are discussed below with respect to Figure 2.

[0026] The secondary coolant enters the liquid tight chassis housing 1 through an inlet quick disconnect connector 2 at the rear of the chassis 1. The coolant then passes through an inlet hose 3 and is split through an inlet manifold 4 (in this case there are two paths, but it will be understood that there could be more paths) over two paths defined by respective inlet piping hoses 5, each of which directs the secondary liquid coolant to a respective cold plate heat sink hybrid device 6. The secondary liquid coolant passes through each cold plate heat sink hybrid device 6 to cool the electronic components to which the device 6 is attached. These are relatively hot electronic components, but are not visible in this view (because of the cold plate heat sink hybrid device 6). After passing through the cold plate heat sink hybrid device 6, the secondary liquid coolant (which is still in liquid form since it is a single phase system) flows through an outlet piping hose 7 to an outlet manifold 8, through an outlet hose 10 and an outlet quick disconnect 11.

[0027] Referring now to FIG. 2, a schematic plan view of the interior of the server chassis 1 shown in FIG. 1 is shown. Where the same features as in FIG. 1 are shown, the same reference numbers are used. This shows the primary (dielectric) liquid coolant loop in more detail. In this respect, the embodiment further includes a base 12; a pump 13; a pump inlet nozzle 14; an outlet nozzle 16; a relatively low temperature component 17; a primary coolant pipe 18; a pump outlet hose 19; and a pump outlet manifold 20. Further details regarding the cold plate heat sink hybrid device 6 are also more visible in that the device 6 comprises a receptacle portion that defines a volume that is outside the cold plate heat sink hybrid device 15. The dielectric coolant typically sits in the base 12 of the liquid-tight chassis 1. A pump 13 takes up the hot liquid dielectric coolant through a pump inlet nozzle 14. The primary liquid coolant travels through pump outlet hose 19 to pump outlet manifold 20, through coolant pipe 18, and into receptacle portion 15 of cold plate heat sink hybrid device 6 via outlet nozzle 16. The primary liquid coolant is then cooled by secondary liquid coolant flowing through the cold plate portion of cold plate heat sink hybrid device 6. The primary liquid coolant pools and overflows receptacle portion 15. The overflowing primary liquid coolant then gathers with other primary liquid coolant and cools all other cold components 17 before or as it returns to pump inlet nozzle 14.

[0028] Typically, the height of the primary liquid coolant in the base 12 is less than the height of the primary liquid coolant held in the receptacle portion 15 of the cold plate heat sink hybrid apparatus 6. In this manner, neither the low temperature component 17 nor the cold plate heat sink hybrid apparatus is submerged by the primary liquid coolant. However, the low temperature component 17 is at least partially submerged in the primary liquid coolant, and the primary liquid coolant receives at least a portion of the heat generated by the low temperature component.

[0029] Referring to Figure 3, there is shown a schematic isolated isometric view of some of the components within the server chassis shown in Figures 1 and 2. This portion relates to the primary liquid coolant loop (or circuit) as described above, although the flow from the receptacle portion 15 of the cold plate heat sink hybrid device 6 to the base 12 of the chassis 1 is not shown in this view. The same reference numbers are used to label the same features as shown in the previous drawings.

[0030] An important aspect of the cold plate heat sink hybrid arrangement 6 is that the primary liquid coolant (and typically all of the primary liquid coolant) is cooled by a secondary liquid coolant loop, specifically by pumping the primary liquid coolant over the cold plate and holding it in a special receptacle portion relative to the cold plate. The secondary liquid (water-based) coolant flowing within the cold plate heat sink hybrid arrangement 6 is cooler than the heated primary (dielectric) liquid coolant, as will be explained further below.

[0031] Referring now to FIG. 4, there is shown, in a schematic manner, an isometric view of the cold plate heat sink hybrid apparatus 6 shown in the previous figures, but in more detail. Referring also to FIG. 5, there is shown an exploded view of the cold plate heat sink hybrid apparatus 6 of FIG. 4, and is used to explain possible constructions and operations of this apparatus. Where the same features as those shown in the previous figures are shown, the same reference numbers are used. The cold plate heat sink hybrid apparatus 6 includes a base 27; an upper housing 22; a cold plate interior volume 23; and a receptacle portion 15 (described above). The base 27 and the upper housing 22 define a closed cold plate interior volume 23 for receiving a secondary liquid coolant. The upper housing 22 also defines the receptacle portion 15. The base 27 is adapted for mounting to an electronic device or component, for example, by means of a mounting hole 28 formed in the base 27. The upper pin 21 is disposed in the receptacle portion 15 and the lower pin 26 is disposed in the cold plate interior volume 23 .

[0032] The interface between the cold plate internal volume 23 and the receptacle portion 15 defines a heat transfer zone between the primary and secondary liquid coolants. The relatively cool (water-based) secondary liquid coolant cools the heat transfer zone and the pins 21 in the receptacle portion 15. This then cools the primary (dielectric) liquid coolant before it floods into the server chassis 1. As the pump 13 is constantly circulating the hot primary liquid coolant through this circuit, all of the primary liquid coolant passes through the cold plate heat sink hybrid device 6, particularly its receptacle portion 15, and is therefore actively cooled by the secondary (water-based) liquid coolant side of the system. By pumping the primary liquid coolant through this loop so that all of the primary liquid coolant is cooled, no stagnation areas of the server chassis 1 (where the primary liquid coolant remains hot) are created. Thus, the heat transfer performance of such an implementation is high.

[0033] Furthermore, cooling all of the primary liquid coolant in the cold plate heat sink hybrid arrangement 6, rather than using a plate heat exchanger (e.g., as described in WO 2019 / 048864), means that the overall pressure drop in the primary liquid coolant loop is significantly smaller. This has several advantages, namely: fewer pumps are needed for this cooling loop, saving space; less pump power is needed, saving energy; valuable space in the chassis 1 is not taken up by one or more plate heat exchangers; the area for cooling the primary liquid coolant is contained on the cold plate 6, which can be kept within a 1U height, with the effect that the primary liquid coolant has a zero footprint in the chassis 1.

[0034] Returning to the generalized meaning discussed above, the substantially unclosed side may be considered to be approximately parallel to a surface of the body that is configured for mounting on the electronic device.

[0035] In an embodiment, the cold plate may further include an outer protrusion formed within the volume of the external receptacle to facilitate heat transfer between the primary liquid coolant and the secondary liquid coolant. For example, the thermal conductor may form a retaining wall that at least partially defines the volume of the external receptacle. In that case, the outer protrusion is advantageously substantially the same size as (and generally parallel to) the height of the retaining wall.

[0036] Additionally or alternatively, the cold plate may further comprise an internal protrusion formed within the internal volume of the thermal conductor to facilitate heat transfer, particularly from the electronic device to the internal volume and / or between the primary and secondary liquid coolants. In a preferred embodiment, the internal protrusion extends substantially between (or the entire distance between) a surface of the internal volume distal to the external receptacle and a surface of the internal volume proximate to the external receptacle. This may provide improved heat transfer and increased structural integrity.

[0037] Optionally, the outer protrusions and / or the inner protrusions comprise pins and / or fins.

[0038] In another generalized aspect that may be combined with any other aspect described herein, a system for cooling electronic devices may be considered, the system comprising a sealable module (e.g., liquid-tight) housing an electronic device and a primary liquid coolant, the system being configured to flow (e.g., by convection and / or pumping) during operation, the system further comprising a cold plate as described herein and having an external receptacle for receiving the primary liquid coolant (and configured to receive a secondary liquid coolant therein) mounted on at least one of the electronic devices (particularly to receive heat from at least one of the electronic devices), and a nozzle arrangement configured to direct the flowing primary liquid coolant into the volume of the external receptacle of the cold plate. The system is advantageously configured such that (all of) the primary liquid coolant is cooled by contact with the cold plate, specifically its external receptacle. Preferably, according to the present disclosure, the system is configured such that all of the primary liquid coolant flows through the volume of the external receptacle of at least one cold plate.

[0039] Advantageously, the primary liquid coolant flows from the nozzle arrangement into the volume of the cold plate's external receptacle and flows (e.g., by overflow) out of the volume of the cold plate's external receptacle to at least partially immerse other electronic devices housed within the sealable module, which other electronic devices typically have a lower operating temperature than the temperature of the electronic devices cooled by the cold plate. In particular, the height of the primary liquid coolant at least partially immersing the other electronic devices housed within the sealable module is lower than the height of the primary liquid coolant held within the volume of the cold plate's external receptacle.

[0040] The system may further include a module coolant inlet for receiving a secondary liquid coolant from outside the sealable module, and an inlet piping arrangement configured to provide the secondary liquid coolant from the module coolant inlet to a coolant inlet of the cold plate. Additionally or alternatively, the system may further include a module coolant outlet for providing the secondary liquid coolant to outside the module, and an outlet piping arrangement configured to provide the secondary liquid coolant from the coolant outlet of the cold plate to the module coolant outlet.

[0041] In an embodiment, the system further includes an inlet manifold coupled to the module coolant inlets and configured to direct the secondary coolant from the module coolant inlets to the inlet piping arrangement. Additionally or alternatively, the system may further include an outlet manifold coupled to the module coolant outlets and configured to direct the secondary coolant from the outlet piping arrangement to the module coolant outlets.

[0042] The system preferably further comprises a pump arrangement configured to direct the primary liquid coolant within the sealable module to a nozzle arrangement of the cold plate. The pump arrangement may have one or more pumps, as discussed below. Convection may assist the flow of the primary liquid coolant, and in some less preferred embodiments, the flow of the primary liquid coolant may be entirely convective. In this case, piping and one or more nozzles are provided to direct the flow of the coolant accordingly.

[0043] A plurality of cold plates may be used, each of which may be configured to cool a respective one or more electronic devices in the module. For example, the cold plate described above in general terms may be considered as a first cold plate. The system may then further comprise a second cold plate mounted on (to receive heat from) at least one other of the electronic devices, the second cold plate having a coolant inlet and a coolant outlet. The second cold plate may be according to any of those described herein, or may be a different, e.g., more conventional, cold plate.

[0044] In some embodiments, the inlet piping arrangement may be further configured to provide the secondary liquid coolant from the inlet manifold to the coolant inlet of the second cold plate. The outlet piping arrangement may be further configured to provide the second liquid coolant from the coolant outlet of the second cold plate to the outlet manifold. In other words, the secondary liquid coolant loops of the first and second cold plates may be provided in parallel.

[0045] Alternatively, the secondary liquid coolant loops of the first and second cold plates may be provided in series, with the outlet piping arrangement then being further configured to provide secondary liquid coolant from the coolant outlet of the first cold plate to the coolant inlet of the second cold plate and from the coolant outlet of the second cold plate to the module coolant outlet.

[0046] If a second cold plate is used, the system may further include a pump manifold configured to direct the primary liquid coolant from the pump to the nozzle arrangement of the first cold plate and the nozzle arrangement of the second cold plate. Additionally or alternatively, the pump arrangement may include multiple pumps, for example a first pump configured to direct the primary liquid coolant to the nozzle arrangement of the first cold plate and a second pump configured to direct the primary liquid coolant to the nozzle arrangement of the second cold plate.

[0047] In embodiments, the system may further comprise a heat exchanger disposed outside the sealable module and configured to receive a secondary liquid coolant from the sealable module and to transfer heat from the secondary liquid coolant, for example, to a fluid (which may be a liquid or a gas). The heat rejection unit may in some embodiments be unitized for this purpose.

[0048] Further details of specific embodiments will now be discussed. Generalized descriptions are also provided in the following points.

[0049] Referring now to FIG. 6, there is shown a schematic cross-sectional view of the cold plate heat sink hybrid device 6 as shown in the previous figures. The same features as previously shown are given the same reference numbers. In this figure, the cold plate heat sink hybrid device 6 is mounted on an electronic component 25 (integrated circuit, IC, etc.). The electronic component 25 is mounted on a substrate 24, which may be a printed circuit board (PCB) or even the base 12 of the chassis 1. Other low temperature components 17 mounted on the substrate 24 are also shown. Both the upper pin 21 in the receptacle portion 15 and the lower pin 26 in the cold plate interior volume 23 are shown. The pin 26 in the cold plate interior volume 23 is full height, extends, contacts and bridges the gap between the base 27 (in contact with the electronic component 25) and the heat transfer zone defined in the upper housing 22. In other words, the pin 26 connects the base 27 to the upper housing (lid) 22 of the cold plate heat sink hybrid device 6. This provides significant benefits to the heat transfer between the primary and secondary liquid coolant, enhancing cooling performance. The full height pins 26 may also improve the strength of the component and eliminate the ability of the coolant to take a shortcut around the pins 26.

[0050] Referring now to FIG. 7, a schematic cross-sectional view of a simplified or modified cold plate heat sink hybrid device 6 is shown. It is essentially the same as that shown in FIG. 6, but without the upper pin 21 and the lower pin 26. The omission of these pins allows further details to be seen. In particular, the height 30 of the primary liquid coolant in the chassis 1 is shown. In this example, the height 30 is sufficient to cover the electronic components 25 (which would be cooled by the cold plate 6 in any case) and to partially cover the low temperature components 17. It can thus be seen that the height 30 of the primary liquid coolant in the chassis 1 is generally low, lower than the height of the primary liquid coolant in the receptacle portion 15 of the cold plate heat sink hybrid device 6 (which extends from the upper housing 22 to the height of the receptacle portion 15).

[0051] Similar to the heat sink described in WO 2019 / 048864, the cold plate heat sink hybrid apparatus of the present disclosure can be mounted either horizontally or vertically to accommodate high temperature components on different format PCBs or motherboards. Referring to FIG. 8, a schematic isolated isometric view of some of the components in a server chassis in a further variation of that shown in FIG. 1 is shown, in which the electronic components to be cooled and the cold plate heat sink hybrid apparatus that cools it are mounted vertically. The same reference numbers label the same features as shown in the other figures. In this embodiment, a vertically mounted cold plate heat sink hybrid apparatus 36 is shown with a vertically oriented PCB 5 on which other low temperature components 37 are provided. This is substantially the same as the previously shown cold plate heat sink hybrid apparatus 6, but with a different configuration of its upper housing to define a slightly different receptacle portion. Whereas the receptacle portion 15 of the previously shown cold plate heat sink hybrid apparatus 6 has an open side opposite the cold plate internal volume, in this modified cold plate heat sink hybrid apparatus 36, the open side of the receptacle portion is adjacent to the cold plate internal volume, allowing the coolant to be retained within the receptacle portion when the cold plate heat sink hybrid apparatus 36 is mounted such that the open side is distal to the base of the chassis. Also, the outlet nozzle 16 is positioned to direct the primary liquid coolant distal to the open side and into the volume of the receptacle portion. This allows the primary coolant to be encouraged to flow within the receptacle portion from the bottom until it overflows at the open side.

[0052] In the general terms discussed above, it may be considered that if the volume of the external receptacle is substantially closed on all sides except one, the substantially non-closed side may be perpendicular to a surface of the body arranged for mounting on the electronic device. In this case, if an outer protrusion is provided and the thermal conductor forms a retaining wall that at least partially defines the volume of the external receptacle, the outer protrusion may advantageously be approximately perpendicular to at least a portion of the retaining wall.

[0053] Referring to FIG. 9, there is shown a schematic isolated isometric view of a portion of a plurality of cold plates and further components in a server chassis in yet another variant. Again, the same features are given the same reference numbers. In this variant, each cold plate heat sink hybrid apparatus 6 has its own individual micro pump 28. The micro pump 28 replaces the need for a single central pump 13 as shown in the previous figures. This has several advantages, namely lower pressure drop; reduced coolant height; reduced cost; partial redundancy (failure of a single micro pump 28 need not prevent successful operation of the system); and the micro pump 28 and cold plate heat sink hybrid apparatus 6 can be installed as a single subassembly. This variant may also be applied to a vertically mounted cold plate heat sink hybrid apparatus 36, for example as shown in FIG. 8.

[0054] In the generalized sense discussed above, each pump of the pump arrangement may form part of (or be integrated with) a respective cold plate. For example, a first pump may form part of a first cold plate and a second pump may form part of a second cold plate. To this end, the pump (or each pump) may be a micropump.

[0055] While specific embodiments have been described, those skilled in the art will appreciate that various modifications and variations are possible. For example, the structure and / or design of the cold plate heat sink hybrid apparatus 6, 36 may differ from that shown. Other shapes and applications are possible. Planar surfaces are preferred, but for example, stepped base (thermal interface) surfaces (having multiple parallel flat surfaces) may be used. Where pins are shown for increased cooling surface area and / or structural improvement, any combination of pins, fins, or other protrusions may be used. Although a specific multi-part cold plate assembly is described, it should be understood that the cold plate heat sink hybrid apparatus may be realized using other multi-part assemblies or as an integrally constructed apparatus. The main flow of primary liquid coolant from the receptacle portion of the cold plate heat sink hybrid apparatus 6, 36 is described by overflow, but additionally or alternatively, holes may be provided in the receptacle portion to allow the primary liquid coolant to flow out to the remainder of the chassis interior volume. Although multiple cold plates are shown in the drawings with their secondary liquid coolant loops in an advantageous parallel configuration, series configurations or combinations of series and parallel configurations are possible.

[0056] All of the 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).

Claims

1. 1. A cold plate configured to use separated primary and secondary liquid coolants, comprising: a thermal conductor defining an interior volume and attached to an electronic device and configured to transfer heat from the electronic device to the interior volume; a coolant inlet for receiving the secondary liquid coolant into the interior volume to receive the transferred heat; a coolant outlet for the secondary liquid coolant to exit the interior volume; The thermal conductor is further configured to define an external receptacle having a volume configured to receive and retain the primary liquid coolant for heat transfer between the primary liquid coolant and the secondary liquid coolant, the cold plate.

2. The cold plate of claim 1 , wherein the volume of the external receptacle is substantially closed on all but one side.

3. The cold plate of claim 2 , wherein the side that is substantially unenclosed is approximately parallel or perpendicular to a surface of the thermal conductor configured for mounting on the electronic device.

4. The cold plate of any one of claims 1 to 3, further comprising an outer protrusion formed within the volume of the external receptacle to facilitate heat transfer between the primary liquid coolant and the secondary liquid coolant.

5. The cold plate of claim 4 , wherein the thermal conductor forms a retaining wall that at least partially defines the volume of the external receptacle, and the outer protrusion is substantially the same size as a height of the retaining wall.

6. 4. The cold plate of claim 1, further comprising an inner protrusion formed within the interior volume of the thermal conductor to facilitate heat transfer from the electronic device to the interior volume and / or between the primary liquid coolant and the secondary liquid coolant.

7. The cold plate of claim 6 , wherein the inner projection extends substantially between a surface of the interior volume distal to the external receptacle and a surface of the interior volume proximate to the external receptacle.

8. 1. A system for cooling an electronic device, comprising: a sealable module housing the electronic device and a primary liquid coolant, the system being configured during operation for the primary liquid coolant to flow, the system further comprising: A cold plate according to any one of claims 1 to 3 attached to at least one of the electronic devices; a nozzle arrangement configured to direct the flowing primary liquid coolant into a volume of the external receptacle of the cold plate.

9. 10. The system of claim 8, further configured to flow the primary liquid coolant from the nozzle arrangement into the volume of the external receptacle of the cold plate and out of the volume of the external receptacle of the cold plate to at least partially immerse other electronic devices housed within the sealable module.

10. 10. The system of claim 9, configured such that a height of primary liquid coolant at least partially immersing other electronic devices contained within the sealable module is less than a height of primary liquid coolant held within the volume of the external receptacle of the cold plate.

11. a module coolant inlet for receiving the secondary liquid coolant from outside the sealable module; a module coolant outlet for providing the secondary liquid coolant to an exterior of the module; an inlet piping arrangement configured to provide the secondary liquid coolant from the module coolant inlet to the coolant inlet of the cold plate; 10. The system of claim 8, further comprising: an outlet piping arrangement configured to provide the secondary liquid coolant from the coolant outlet of the cold plate to the module coolant outlet.

12. an inlet manifold coupled to the module coolant inlet and configured to direct the secondary coolant from the module coolant inlet to the inlet piping arrangement; 12. The system of claim 11, further comprising an outlet manifold coupled to the module coolant outlet and configured to direct the secondary coolant from the outlet piping arrangement to the module coolant outlet.

13. The cold plate is a first cold plate, and the system further comprises: a second cold plate mounted on at least one other of the electronic devices, the second cold plate having a coolant inlet and a coolant outlet; 13. The system of claim 12, wherein the inlet piping arrangement is further configured to provide the secondary liquid coolant from the inlet manifold to the coolant inlet of the second cold plate, and the outlet piping arrangement is further configured to provide the secondary liquid coolant from the coolant outlet of the second cold plate to the outlet manifold.

14. The cold plate is a first cold plate, and the system further comprises: a second cold plate mounted on at least one other of the electronic devices, the second cold plate having a coolant inlet and a coolant outlet; 12. The system of claim 11, wherein the outlet piping arrangement is further configured to provide the secondary liquid coolant from the coolant outlet of the first cold plate to the coolant inlet of the second cold plate and from the coolant outlet of the second cold plate to the module coolant outlet.

15. The system of claim 13, wherein the second cold plate is in accordance with any one of claims 1 to 3.

16. The system of claim 8 , further comprising a pump arrangement configured to direct the primary liquid coolant within the sealable module to the nozzle arrangement of the cold plate.

17. The cold plate is a first cold plate, and the system further comprises: A second cold plate according to any one of claims 1 to 3; 17. The system of claim 16, comprising: a pump manifold configured to direct the primary liquid coolant from the pump to the nozzle arrangement of the first cold plate and to the nozzle arrangement of the second cold plate.

18. The cold plate is a first cold plate, and the system further comprises: Further comprising a second cold plate according to any one of claims 1 to 3, 17. The system of claim 16, wherein the pump arrangement includes a first pump configured to direct a primary liquid coolant toward the nozzle arrangement of the first cold plate, and a second pump configured to direct a primary liquid coolant toward the nozzle arrangement of the second cold plate.

19. 20. The system of claim 18, wherein the first pump forms part of the first cold plate and the second pump forms part of the second cold plate.

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