Active-passive immersion cooling system

Abstract

Liquid cooling apparatus and system for the immersion cooling of electronic devices including in particular servers and IT hardware nodes having an array of heat generating electronic components including for example microprocessors, GPUs, CPUs, RAM, motherboards etc. The present apparatus comprises at least one rotor adapted for creating a liquid flow stream localised to the electronic component(s) for the efficient and effective forced convection cooling according to an active cooling arrangement. The present arrangement is configured for both active and passive operation and is adapted specifically not to obstruct passive liquid flow adjacent an electronic component when the at least one rotor is not operational.

Description

[0001] Active-Passive Immersion Cooling System

[0002] Field of invention

[0003] The present invention relates to liquid cooling systems for the effective and efficient cooling of heat-generating electronic components and in particular, although not exclusively, to apparatus and method to cool IT components, servers, computational electronic devices and the like via direct submersion of such components and devices in a dielectric liquid coolant.

[0004] Background

[0005] The cooling of electronics, specifically IT components, servers, data storage devices and computational electronic devices having graphics and central processing units (GPUs and CPUs) has become a major technical challenge due to the ongoing development of smaller, faster, higher density and higher power capacity electronics. Computing devices produce heat as a by-product of operational processing. In datacentres, where thousands of such devices are located, the amount of heat generated can be extremely large. As the need for access to greater processing and data storage continues to expand, the density of server systems continues to increase, and the resulting thermal challenges present a significant practical obstacle.

[0006] Conventional fan-based cooling systems require large amounts of power. Accordingly, the power demand to drive such systems increases significantly with the increased server densities. Immersion cooling of IT components is a relatively recent development. The operational hot electronics are submerged in direct contact with a dielectric (electrically insulating) coolant liquid that is circulated and cooled through the use of heat exchangers and the likes. Cooling of electronics enhances their performance, enabling higher processing speeds (for example the overclocking of CPUs) whilst reducing power consumption by minimising current leakage. The heat generated by the circuit is removed quickly and efficiently by the dielectric liquid directly at the heat source. However, there is a general need for continued improvement of the operational efficiency of existing liquid submersion cooling systems with regard the effectiveness of the cooling of the electronic components.

[0007] Additionally, within single-phase immersion cooling, heat sinks are commonly used to dissipate heat generated by electronic components such as CPUs, GPUs, and power supplies. These heat sinks act passively within an immersion cooling system as typically there is no source of localized forced convection to accelerate the liquid through the heat sink. Due to the favourable thermal characteristics of existing immersion cooling dielectric liquids, passive heat sinks have proved to be more than adequate. However, as electronic devices and in particular heat generating electronic components continue to be developed and configured to operate at higher heat fluxes, there is a need for improved arrangements for efficient and effective cooling of such components. Summary of the Invention

[0008] One objective of the present concept is to provide an active-passive immersion cooling system for electronic devices (having at least one heat generating electronic component) with improved heat transfer by use of forced convection of a dielectric cooling liquid relative to the heat generating electronic component. It is a specific objective to provide a cooling apparatus and a method for electronic components operable with both active and passive immersion cooling modes for enhanced energy usage, cooling efficiency and fault tolerance.

[0009] Accordingly, an active-passive immersion cooling system is provided to be compatible with an otherwise passive immersion cooling system. The present concept is particularly advantageous to be removable / replaceable at new and existing passive cooling configurations. The present active-passive arrangement is provided by at least one rotor configured to be rotatably driven relative to a rotor housing and / or the electronic device / component to create and maintain a flow stream of the dielectric liquid past the electronic component / device so as to create an active forced convection cooling arrangement. The at least one rotor, optionally implemented as a propeller or impeller, is adapted to propel the liquid at relatively high velocity. Additionally, the rotor is configured such that an aperture at the rotor housing, within which the rotor is mounted, comprises a generally "open ’ cross sectional area such that a cross sectional region or size of the rotor (occupying the rotor housing aperture) is minimised and in particular is less than the surrounding "open ’ cross sectional area (not occupied by the rotor). Such an "open ’ cross sectional area is defined as the region not obstructed / obscured by the rotor (where the rotor is defined as a body comprising a central hub and rotor blades extending radially outward from the hub). In particular, it may be a feature of the rotor blades to comprise a relatively high aspect ratio i.e., to be longer and thinner relative to existing prior art fan blades conventionally associated with air-cooling CPU and GPU fans mounted at a respective heat sink body that, in turn, is attached or mountable at the heat generating electronic components. In addition, the number of rotor blades according to the present concept is minimised and is typically less than the conventional fan blades associated with air-cooling CPU and GPU fans. An advantage of the present concept comprising a rotor to drive liquid flow streams, is to provide a redundancy feature such that should rotation of the rotor terminate (for example due to failure of the normal operation of an associated rotor drive motor), the dielectric cooling liquid is still capable of flowing past the rotor due to the passive flow associated with the general circulating flow of dielectric cooling liquid within the liquid container or immersion tank.

[0010] Additionally, when the present system is configured to be inactive such that cooling is provided as a passive arrangement only, the aforementioned characteristics minimise hindrance of the passage of liquid past the rotor and in contact with a heat sink body located at the heat generating electronic component. As will be appreciated, the present rotor may be inactive due to IT hardware being purposely deactivated or operated at a very low rotational speed (for example where a GPU or CPU is operated at low operating levels).

[0011] As will be appreciated, the present system may comprise a single or a plurality of rotors each with respective radial rotor blades and optionally provided at a rotor housing being positioned within respective apertures at the housing. The present system may be provided with redundancy operational procedures should rotation of at least one rotor fail, one or more additional rotors are operable and may be activated and / or configured for enhanced rotational speed to compensate for any inactive / failed rotor.

[0012] Advantageously, the present rotor arrangement may be part of a removable attachment to a heat sink to allow for easy replacement of the propeller / impeller without the need to remove the heat sink from the IT hardware to which it is attached. The present arrangement is compatible with additional liquid flow directing devices such as baffles, other static devices and liquid flow circulation pumps associated with active and / or passive immersion cooling.

[0013] According to a first aspect of the present concept there is provided cooling apparatus to remove heat from a heat-generating electronic component immersed within a dielectric coolant liquid comprising: at least one heat-generating electronic component; at least one heat sink configured to receive thermal energy from a main face of the heat-generating electronic component and having a base and a plurality of heat transfer members each projecting from the base and terminating at respective terminal ends or edges, the members defining a least one side face of the heat sink extending between the base and the ends or edges, a terminal end face of the heat sink positioned opposed to the base and defined by terminal ends or edges; regions between the members defining flow ducts extending laterally across the heat sink between the base and the terminal end face; a support body having at least one mount region to receive and mount at least one rotor and an attachment region to attach the support body to the heat sink; at least one rotor rotatably mounted at the mount region; and at least one motor to drive rotation of the rotor at the support body and create at least one flow stream of the dielectric coolant liquid; wherein the support body is configured such that at least one rotor is positioned opposed to the at least one side face of the heat sink so as to direct the at least one flow stream through the flow ducts and laterally across the heat sink between the base and the terminal end face.

[0014] Reference within this specification to a "main face ’ refers to the largest surface area face of a heat-generating electronic component such as a GPU, CPU etc. Typically, such a largest face is substantially planar and is orientated to face away from an electronic device upon which the heat-generating electronic component is mounted, such as a circuit board, mother board etc.

[0015] Reference within this specification to ‘at least one side face of the heat sink’ encompasses a side wall or side face of a block-shaped heat sink body in which the block is defined by a base and heat transfer members projecting from the base. Optionally, the heat sink may comprise a cuboidal shape profile such as a square or rectangular cuboid. Reference to the 'at least one side face ’ encompasses side walls or faces orientated approximately perpendicular to the board upon which the heat-generating electronic component and the heat sink are mounted, the board optionally comprising a printed circuit board, mother board etc.

[0016] Reference within this specification to ‘heat transfer members ’ encompasses blades, fins, plates, fingers, pins, columns arranged to extend as a regular array of members. The term encompasses members being formed from a high thermal conductivity material such as a metallic or suitable ceramic material. As will be appreciated, heat transfer from such members including convention of the surrounding medium (i.e., dielectric fluid) and radiation.

[0017] Optionally, the support body may comprise a degree of flexibility so as to be capable of being at least partially bent or deformed and then clipped onto the heat sink via resiliently biased frictional contact between the support body and at least a part of the heat sink. Preferably, the support body comprises a substantially planar section having at least one or two end walls that may be clipped onto a heat sink to sit against at least one side face of the heat sink.

[0018] According to certain embodiments, the heat sink is provided at the main face of the heatgenerating electronic component. The heat sink may be secured in position at a heatgenerating electronic component using attachment means (typically mechanical) as will be appreciated. Optionally, the radiation members comprise a plurality of fins arranged in rows to define the liquid flow ducts extending between the fins, the fins and the base defining the heat sink as a generally block-shaped body. The fins may extend lengthwise at the heat sink body where the heat sink comprises a generally rectangular cuboid shaped profile. Optionally, the radiation members comprise a plurality of elongate pins or fingers projecting from the base to define the liquid flow ducts extending between the pins or fingers, the base and the pins or fingers defining the heat sink as generally block-shaped body. Reference within this specification to a ‘ block-shaped body ’ when referring to a heat sink or heat spreader, encompasses arrangements in which a generally metallic body comprises a series of fins and / or plate-like bodies (base plates) such that the collection of the fins and base plate defines a generally rectangular cuboid body according to conventional heat sink devices typically associated with the cooling of electronic components such as GPUs, CPUs etc.

[0019] Preferably, the at least one rotor is positioned at the side face of the block-shaped body adjacent an entrance or exit end of the ducts. Preferably, the rotor housing may be releasably attachable to the heat sink and / or to the electronic device to locate the rotor at the entrance of the ducts. The rotors as described and claimed herein are configured and are positioned to create a liquid flow stream locally at a heat sink and / or the heat-generating electronic. This is to be contrasted with a liquid flow pump or device typically associated with the driving circulation of cooling liquid within a liquid flow network (that includes an immersion cooling tank) and positioned remote to the heat sink and / or the heat-generating electronic. That is, the present rotors are mounted directly within the chamber containing the cooling liquid and are located adjacent, close to, neighbouring or localised to the electronic components to create the fluid flow streams of cooling liquid adjacent to the at least one electronic component.

[0020] Optionally, the heat sink may comprise a heat pipe, heat-transfer device comprising at least one first module to mount to the at least one heat-generating electronic component; a heat spreader module connected to the first module in internal fluidic communication; and a liquid contained within the heat pipe heat-transfer device and configured to circulate between the first module and the heat spreader module and to undergo phase change within the device including an evaporation and condensation cycle. Optionally, the support body and the rotor are mounted at the heat spreader module. Accordingly, in such an arrangement, heat energy is transferred from the heat-generating electronic component to the first module and then to the heat spreader (via the internal liquid undergoing the phase change cycle), with the at least one rotor then configured to create the liquid flow stream over and about and in particular through the heat spreader for heat dissipation into the dielectric cooling liquid. Accordingly reference to a heat spreader is equivalent to reference to a heat sink.

[0021] Optionally, the heat-generating electronic component comprises any one or a combination of an integrated circuit; an integrated circuit chip; a motherboard; random access memory (RAM); a graphics processing unit (GPU); a central processing unit (CPU). Optionally, the at least one heat-generating electronic component is mounted at an electronic device comprising any one or a combination of a computer entity; a server; a motherboard; a printed circuit board comprising a plurality of electronic components; an integrated circuit. Optionally, the rotor mount region comprises at least one aperture to at least partially accommodate and allow rotation of the at least one rotor. Optionally the rotor mount region comprises a support fixing to enable releasable attach of the rotor whilst allowing the rotor to rotate when mounted in position. A suitable support fixing may comprise arms, spokes, protections etc and as will be appreciated to positionally support a rotor via an axle, central boss or hub about which the rotor is capable of rotation. Optionally the rotor may be mounted at its perimeter via radially outer regions of rotor blades. Such an arrangement may comprise the tips of the rotor blades (or a radially outer rotor ring) being received and accommodated within an annular race, groove or channel provided at the support body.

[0022] Optionally, the rotor comprises not more than six blades or wherein the rotor comprises two to six, two to five, two to four or two or three blades projecting radially outward from a central boss. Optionally, the rotor may be a propeller or an impeller. Optionally, the apparatus may comprise a plurality of rotors mounted at one or a plurality of different positions at a heat sink device, with at least some of the rotors comprising a propeller and at least some of the rotors comprising an impeller.

[0023] Optionally, the support body may comprise a cover portion configured to sit over and about at least a part of the heat sink. Optionally, the cover portion may be configured to sit over the main face of the heat-generating electronic component so as to prevent or inhibit flow of the dielectric coolant liquid through the main face. The cover portion is adapted to effectively close, and in particular inhibit, liquid flow to and from the heat sink at the position of the cover. This, in turn, promotes liquid flow through the region of the heat sink where the at least one rotor is mounted. The cover may be positioned over one or a plurality of faces of a block-shaped heat sink body. Preferably, the rotor is positioned proximate and / or immediately adjacent the at least one side face of heat sink.

[0024] According to a further aspect of the present concept there is provided an immersion liquid cooling assembly comprising: the apparatus as claimed herein; and a container defining a chamber to contain a dielectric coolant liquid and at least one electronic device immersed within the liquid, the electronic device mounting the at least one heat-generating electronic component.

[0025] Optionally, the electronic devices may be arranged in a generally vertical orientation within the chamber such that a lengthwise first end of each electronic device is positioned closest to a trough of the chamber relative to a second lengthwise end of each electronic device positioned closest to upper region of the chamber; and wherein the cooling apparatus and in particular the rotor is positioned at or towards the first lengthwise end closest to the trough relative to the second lengthwise end of the electronic devices.

[0026] Preferably, the at least one rotor is positioned between the heat sink and a base face of the container that, in part, defines the trough of the chamber. That is, preferably the rotors are located towards a lower region of the immersion cooling tank at or towards the tank trough to push / drive the liquid upwardly. This is advantageous to drive cooled dielectric liquid (at the lower region of the tank) as a liquid flow stream onto the electronic components so as to work with the natural convection flow of the cooling liquid from the lower region to the upper region of the immersion tank. Optionally, the at least one rotor is positioned at an upper region of the chamber between the heat sink and an air-liquid interface (the surface of the dielectric liquid within the tank). In such a configuration, the rotor is configured to pull liquid upward from the trough of the chamber to the liquid surface.

[0027] Optionally, the assembly may comprise at least one liquid flow inlet and at least one liquid flow outlet provided at the container to allow a flow of the liquid to enter and exit respectively the chamber in direct contact with the electronic devices; and a cooling unit provided in fluidic communication with the chamber to cool the liquid and being provided in fluidic communication with at least one of said inlet and said outlet to form a fluid flow network to transfer heat energy from the heat-generating electronic components to the liquid. Optionally, the assembly may further comprise a liquid flow pump connected in fluidic communication with the inlet and / or the outlet of the container to drive a flow of the liquid to and from the chamber. Preferably, the cooling unit may comprise a heat exchanger to transfer heat energy from the liquid to a heat transfer fluid. The heat exchanger may comprise a secondary liquid flow network containing the heat transfer fluid according to conventional heat exchanger arrangements. The cooling unit may be integral but may be removably mounted at the cooling apparatus. Optionally, the cooling unit is located locally or remotely relative to the liquid containing chamber and / or the container. Optionally, the present arrangement is suitable for use with immersion tanks that do not comprise a fluid inlet / outlet. As will be appreciated, such systems pump water into a heat exchanger at or near the top of the tank filled with fluid and the fluid is cooled via natural convection.

[0028] According to a further aspect of the present concept there is provided a method of removing heat from a heat-generating electronic component comprising: immersing at least one heat-generating electronic component within a dielectric coolant liquid; providing at least one heat sink to receive thermal energy from a main face of the heat-generating electronic component, the heat sink having a base and a plurality of heat transfer members each projecting from the base and terminating at respective terminal ends or edges, the members defining a least one side face of the heat sink extending between the base and the ends or edges, a terminal end face of the heat sink positioned opposed to the base and defined by terminal ends or edges, wherein regions between the members defining flow ducts extending laterally across the heat sink between the base and the terminal end face; providing a support body having at least one mount region to receive and mount at least one rotor and an attachment region to attach the support body to the heat sink and position the rotor opposed to the at least one side face of the heat sink; creating a flow stream of the liquid through the flow ducts and laterally across the heat sink between the base and the terminal end face by driving rotation of the rotation of rotor at the support body.

[0029] Optionally, according to aspects of the present method, the container is an immersion tank containing a plurality of electronic devices each mounting at least one heat-generating electronic component, the electronic devices arranged in a generally vertical orientation within the chamber such that lengthwise ends of the devices are positioned closer to a trough region of the chamber relative to lengthwise second ends of the devices positioned closer to an open upper region of the chamber; wherein the rotor is positioned at or towards the first ends of the electronic devices; and wherein the fluid stream is directed generally upward in a liquid flow direction extending from the trough to the open upper region of the tank. According to alternate embodiments, the container may be a tray or other similar shaped container mountable at a rack system in which a plurality of trays, each individually containing dielectric liquid and a respective electronic device, are mounted.

[0030] According to a further aspect of the present concept there is provided liquid cooling apparatus for an electronic device comprising: a container defining a chamber to contain a dielectric cooling liquid and at least one electronic device immersed within the liquid and having at least one heat-generating electronic component; a cooling unit provided in fluid communication with the chamber to cool the liquid; and a rotor assembly having a rotor positioned within the chamber and a motor to drive rotation of the rotor and provide a flow stream of the liquid relative to the heat-generating electronic component.

[0031] Optionally, the container is a liquid immersion tank to contain a plurality of electronic devices having respective heat generating electronic components.

[0032] According to preferred embodiments, the cooling apparatus comprises a plurality of rotors. Preferably, each of the rotors are independently drivable by at least one motor. Optionally, the at least one motor may be located locally or remotely relative to the rotatable rotor.

[0033] Optionally, the at least one motor may be located within the chamber and immersed within the cooling liquid.

[0034] Optionally, the rotor housing extends over all or a majority of the at least one side face of the block-shaped heat sink body. Optionally, the heat sink may be positioned in physical contact with and to cover the heat generating electronic component.

[0035] According to a further aspect of the present concept there is provided a method of cooling at least a portion of an electronic device comprising: immersing an electronic device having at least one heat-generating electronic component within a dielectric cooling liquid contained within a chamber defined by a container; immersing the heat generating electronic component within the liquid; cooling the liquid heated by the electronic device and / or the heat-generating electronic component using a cooling unit provided in fluidic communication with the chamber; and creating a flow stream of the liquid within the chamber relative to the heat-generating electronic component using a rotor assembly having a rotor positioned within the chamber and being rotatably driven by a motor.

[0036] Optionally, the container is an immersion tank containing a plurality of electronic devices arranged in a generally vertical / upright orientation within the chamber such that a lengthwise end of this device is positioned adjacent to a trough region of a chamber and a lengthwise second end of each device is positioned adjacent to an open upper region of the chamber; wherein the rotor is positioned at, towards or adjacent the first ends of the electronic devices and closer to a trough region of the tank relative to an upper region of the tank; and wherein the fluid stream is directed generally upward from the trough region to the upper region of the tank.

[0037] Preferably, the method comprises creating a plurality of flow streams using a plurality of rotors positioned respectively adjacent the trough region of the tank, each flow stream directed generally upward in a direction from the tank trough region to the tank upper region.

[0038] According to a further aspect of the present concept there is provided cooling apparatus to remove heat from a heat-generating electronic component immersed within a dielectric coolant liquid comprising: a support body having at least one mount region to receive and mount at least one rotor and an attachment region to attach the support body to a heat sink provided at a heat-generating electronic component to be cooled; and at least one rotor rotatably mounted at the mount region; the rotor configured and positionable to create at least one flow stream of dielectric coolant liquid adjacent, proximate, onto and / or through at least a region of the heat sink.

[0039] Brief description of drawings

[0040] A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a liquid immersion cooling tank for the control refrigeration of a series of electronic devices according to one specific implementation of the present concept;

[0041] Figure 2 is a perspective view of part of the liquid cooling apparatus of figure 1 having a plurality of rotors to create liquid flow streams within the immersion cooling tank;

[0042] Figure 3 is an exploded view of the liquid cooling apparatus of figure 2;

[0043] Figure 4 is a perspective view of the rotor assembly and a housing forming a part of the cooling apparatus of figure 2;

[0044] Figure 5 is an underside perspective view of the rotor assembly and housing of figure 4;

[0045] Figure 6 is a perspective view of the rotor assembly and housing of figures 4 and 5 mounted in position at a heat sink;

[0046] Figure 7 is an end view of the rotor assembly, housing and heat sink of figure 6;

[0047] Figure 8 is a further embodiment of the present concept relative to figure 6 including an additional set of rotors positionable at a second lengthwise side of a heat sink;

[0048] Figure 9A is a perspective exploded view of the arrangement of figure 8;

[0049] Figure 9B is a perspective view of a side face and adjoining end face of a heat sink comprising a plurality of plate-like fins projecting from a base according to a specific implementation of the present concept;

[0050] Figure 9C is a perspective view of a side face and adjoining end face of a heat sink comprising a plurality of pins projecting from a base according to a further specific implementation of the present concept; Figure 10 is a perspective view illustrating the interior of the immersion cooling tank of figure 1 housing an electronic device and liquid cooling apparatus within a dielectric cooling liquid according to a specific implementation of the present concept; and

[0051] Figure 11 is a perspective view of a liquid immersion cooling rack having separate container trays to house the liquid and respective electric devices to be cooled according to a further specific embodiment of the present concept.

[0052] Detailed description of preferred embodiment of the invention

[0053] According to specific embodiments, liquid cooling apparatus and a system is provided for the immersion cooling of electronic devices including in particular servers and IT hardware nodes having an array of heat generating electronic components including for example microprocessors, GPUs, CPUs, RAM, motherboards etc. The present apparatus comprises at least one rotor adapted for creating a liquid flow stream localised to the electronic component(s) for the efficient and effective forced convection cooling according to an active cooling arrangement. The present apparatus and system is configured for both active and passive operation and in particular not to obstruct passive liquid flow adjacent an electronic component when the at least one rotor is not operational.

[0054] Referring to figure 1, an immersion cooling tank (alternatively termed bath) 10 comprises an internal chamber 14 to accommodate a plurality of IT electronic devices 13, alternatively termed IT hardware nodes and including servers, electronic boards and the like. Each electronic device 13 mounts an array of heat generating components (HGCs) in the form of on-board electronic components that may typically comprise relatively low heat generating components (eg RAM, the motherboard and the like) and relatively high heat generating components (eg microprocessors, CPUs, GPUs). Such components may themselves have different maximum operating temperatures. A dielectric cooling liquid 11 is housed within chamber 14 as defined by container 12, alternatively termed an immersion cooling tank. Referring to figures 2 and 3, the present liquid cooling apparatus 20 is mountable at each respective electronic device 13 so as to provide an active cooling function localised to a respective electronic component an in particular a specific HGC, mounted at the electronic device 13 (typically a printed circuit board, motherboard and the like). Device 13 typically comprises a plurality of HGCs including for example a GPU and / or CPU 21 and RAM 19. The present cooling apparatus comprises a plurality of rotor assemblies 17 provided at a rotor housing 15 that in turn is mountable to a respective heat sink 16. Heat sink 16, is in turn, mountable in direct contact with electronic component 21 (situated at the largest face of device / board 18). According to one embodiment, rotor housing 15 is configured to clip onto heat sink 16 so as to be removably and detachably fixed in position at electronic device 18 and at least partially conceal and overlay heat sink 16 and thereby indirectly cover and be positioned immediately adjacent electronic component 21.

[0055] According to the specific embodiment, rotor housing 15 comprises a generally planar plate-like cover 15a to sit over and about an upward facing largest face 16a of the generally cuboid-shaped heat sink 16. A sidewall (alternatively termed a side flange) 15b extends from one side edge of cover 15a being orientated perpendicular to cover 15a. Side wall 15b is configured for positioning opposed to a first lengthwise side face 16c of heat sink 16 when rotor housing 15 is clipped into position over and about heat sink 16. As illustrated in figure 3, heat sink 16 comprises a second lengthwise side face 16d and an underside face 16b positionable opposed to and in touching contact with electronic component 21. Whilst not illustrated, heat sink underside face 16b may typically comprise a cavity or recess into which is received electronic component 21, with heat sink 16 mounted in attached contact at electronic device 18.

[0056] Referring to figures 4 and 5, the present liquid cooling apparatus comprises a plurality of rotors 17 all mounted at side wall 15b. Side wall 15b comprises a plurality of apertures 22 within which a respective rotor 17 is mounted. In particular, each rotor 17, comprises a central boss 17b from which extends radially a pair of rotor blades 17a. Boss 17b is mounted at a rotation axle (not shown), in turn, mounted at side wall 15b via a respective rotor mount 35. Accordingly, each rotor 17 is capable of rotation about its mounting axle so as to rotate freely within each respective aperture 22. According to the specific implementation, each rotor 17 is connected electronically to a suitable drive motor (not shown) for the electronically controllable rotational drive of each respective rotor. According to further implementations, a single drive motor may be provided and operable for all or some of the rotors whilst other embodiments may comprise a respective motor to drive one or some of the individual rotors. As will be appreciated, the present arrangement typically comprises suitable control software to control the rotational speed and state function of each rotor 17 as desired. Additionally, the present cooling apparatus and method may comprise sensors such as rotational speed sensors, liquid flow sensors etc mountable or associated with each rotor 17 and / or rotor housing 15 so as to provide suitable electronic control and monitoring of cooling performance. As illustrated in figures 4 and 5, each aperture 22 is defined by a short cylindrical section 23 that projects outwardly from side wall 15b and comprises and internal cylindrical surface 24 (figure 7) that defines each aperture 22 and its internal volume. According to the specific embodiment each aperture 22 forms a liquid flow inlet port to the interior of the cooling apparatus 20 that includes the electronic component 21 to be cooled. Each rotor 17 is accordingly accommodated within each cylindrical section 23 (inlet port) to be freely rotatable therein.

[0057] With the rotors and rotor housing mounted in position to at least partially conceal heat sink 16 as illustrated in figure 6, rotors 17 are positioned immediately adjacent heat sink side face 16c (figure 8). As further illustrated in figure 7 each of the rotors and in particular rotor blades 17a are positioned immediately in front of heat sink side face 16c such that the rotation axis of each rotor is aligned parallel with the main length of heat sink 16. According to a conventional design, heat sink 16 comprises a plurality of generally planar plate-like fins 25 projecting upwardly from a rectangular base 27. Each of the fins comprise a respective first side face 25a and an opposed second side face 25b. A plurality of liquid flow channels or ducts 26 are defined between the lengthwise and widthwise extending side faces 25a, 25b. With the cooling apparatus submerged within the dielectric liquid 11 (figure 1) the dielectric liquid is capable of free flowing within ducts 26 to be effective to transfer heat generated from the electronic component 21 to the cooling liquid 11 via each of the heat sink fins 25. As illustrated in figure 7, according to the present implementation, each rotor comprises a pair of rotor blades 17a aligned 180° apart. In order to provide a redundancy flow of liquid through each aperture 22, in the event of non-rotation of a rotor, the present cooling apparatus is configured such that a cross sectional region or size of the rotor (including rotor blades and central boss) is minimised relative to the cross-sectional area of the aperture and in particular is less than the aperture cross-sectional area. This creates an "open" aperture in which the size or area obstructed / obscured by the rotor (where the rotor is positioned within the aperture) is less than the size of the cross-sectional area of the aperture adjacent and / or surrounding the rotor 17. In particular, the rotor may occupy less than 50, 40, 30, 20 or 10% of the total cross-sectional area of the aperture (without the rotor mounted in position). Such an arrangement is beneficial to maintain liquid flow through the cooling apparatus and in particular through ducts 26 so as to provide at least passive cooling of electronic component 21. However, with rotors 17 actively driven, the present cooling apparatus is adapted for active cooling via the forced or driven liquid flow streams through ducts 26 and in a generally lengthwise direction between heat sink sides 16c and 16d. In particular, according to the embodiment of figures 2 to 7, liquid flow is driven in a direction vertically upward at chamber 14 through apertures 22 and lengthwise through ducts 26 from side face 16c to side face 16d.

[0058] Figures 8 and 9A illustrate a further embodiment of the present cooling apparatus in which rotor housing 15 comprises a pair of opposed side walls 15b, each mounting a series of rotors 17. With the rotor housing 15 mounted in secured detachable position over and about heat sink 16, each respective heat sink side face 16c and 16d is at least partially concealed by a respective side wall 15b. In such an embodiment, enhanced liquid flow streams are provided due to the additional flow drive from the second set of rotors (mounted at the exit end of each of the ducts 26) relative to the first set of rotors 17 (mounted at the entrance end of each of the ducts 26). Such an arrangement is further advantageous to provide additional redundancy should one of the set of rotors fail.

[0059] Referring to figure 9B, each of the fin-like heat transfer members 41 are arranged parallel (or approximately parallel) with one another to be upstanding from base 27. In particular, a first lengthwise extending side 41a of each member 41 is positioned at base 27 whilst corresponding second lengthwise extending sides 41b are defined exposed terminal ends of members 41. A respective lengthwise end 41c of each plate-like heat transfer member 41 defines each respective side face 16c of heat sink 16. Additionally, each of the lengthwise extending side 41b of each member 41 defines a main face 16a of the heat sink. Accordingly, the planar plate-like cover 15a is configured to sit over and about heat sink main face 16a. As will be appreciated, each of the terminal ends 41b are coplanar so as to define the substantially planar main face 16a.

[0060] Referring to figure 9C, a further embodiment of the heat sink 16 comprises a plurality of pins 42 upstanding from base 27. In particular, a first lengthwise end 41a of each pin is provided at / attached to base 27 whilst a second end 41b represents a terminal end of each pin 42. According to the embodiment of figure 9C, each pin extending between ends 41a, 41b to define each side face 16c of heat sink 16 whilst the array of terminal ends 14b collectively define main face 16a. As with the embodiment of figure 9B, each of the terminal ends 41b are coplanar with one another so as to define the substantially planar main face 16a.

[0061] Referring to figure 10, and in use, the present cooling apparatus is attachable to electronic device 13 that, in turn, is submerged within dielectric liquid 11 contained within chamber 14. As noted, with rotors 17 electronically driven, dielectric liquid is drawn / forced into heat sink 16 and in particular though the flow ducts 26 (liquid flow arrows 30) via the side face 16c (entrance ends of the ducts). The cooling dielectric liquid then flows vertically upward and lengthwise in contact with heat transfer fins 25 to then exit ducts 26 at the respective side face 16d (exit ends of the ducts) as illustrated by liquid outflow arrows 31 and in a direction between a chamber base face 28 (defining the chamber trough) and the upper open-end region 29 located at an upper portion of chamber 14. A plate-like electronic device 13 is mounted in generally vertical orientation to extend lengthwise between trough 28 and upper open-end region 29. Accordingly, rotors 17 mounted at heat sink end face 16c are located proximal (i.e., adjacent, near, close) to chamber trough face 28 at a lower region of the chamber relative to upper open-end region 29. A liquid flow outlet 32 is provided at or proximal to upper open-end region 29 of chamber 14 and a liquid flow inlet 33 is positioned at or proximal to chamber trough face 28 at a lower region of the immersion tank. A cooling unit 34, according to the specific embodiment, is mounted at tank 10 in fluidic communication with the respective outlets and inlets 32, 33. Cooling unit 34 comprises a heat exchanger (not shown) and a liquid flow pump (not shown) to provide and drive passive circulation of the dielectric cooling liquid between the open upper region 29 and the lower trough region (in part defined by face 28) according to conventional arrangements in which heated dielectric liquid, due to natural convection, is drawn from the upper regions of the body of liquid through the cooling device to be then reintroduced at the chamber trough (lower) region at a lower temperature. With the cooling apparatus located and arranged as illustrated in figure 10, the cooled dielectric liquid flowing from inlet 33 is driven into contact with the electronic components 21 via the rotors 17 located immediately adjacent to the electronic components 21. The positioning of the rotors 17 immediately adjacent the lower region of the chamber 14 is advantageous to enhance the natural convection and circulating flow of dielectric liquid between the respective lower and upper regions of the chamber 14 whilst directing cooling liquid flow streams locally at each electronic component 21.

[0062] According to further embodiments and as illustrated in figure 11, the present cooling apparatus is compatible for use with a support rack arrangement 36 in which a plurality of IT hardware nodes are mounted within a generally upstanding frame that in turn mounts a plurality of horizontal rails 37. A plurality of respective trays 38 are slidably mounted at each of the rails 37, with each tray comprising a horizontally aligned chamber 39 configured to accommodate an IT hardware node (electronic device 13). The dielectric cooling liquid is contained within each of the trays at the horizontally aligned chambers 39, with the electronic devices 13 immersed within the liquid within each respective tray chamber 39. Accordingly, the electronic devices 13 are mounted above one another as a liquid immersed vertical stack / array. According to such further embodiments, the present cooling apparatus comprising at least one actively driven rotor may be implemented as illustrated in figures 2 to 10. Alternatively or in addition, rotors 17 may be configured and positionable opposed to the upward facing largest face 16a of heat sink 16.

[0063] Additionally, according to further embodiments, the present cooling apparatus may comprise at least one rotor mountable in position adjacent the at least one electronic component 21 and immersed within dielectric cooling liquid 11 without an additional housing 15. That is, the at least one drivable rotor 17 may be mounted or suspended in position via suitable attachments or mounting arrangements and may be used with or without a heat sink 16. According to all embodiments herein, the rotor is immersed directly within the dielectric cooling liquid close to (neighbouring, adjacent, proximal, opposite) electronic component 21, 19 to provide localised liquid flow streams directed to electronic component 21, 19.

[0064] Unless defined otherwise all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently described subject matter pertains.

[0065] Where a range of values is provided, for example, concentration ranges, percentage ranges, or ratio ranges, it is understood that each intervening value, to the tenth of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the described subject matter. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and such embodiments are also encompassed within the described subject matter, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the described subject matter.

[0066] It should be understood that the terms "a" and "an" as used above and elsewhere herein refer to "one or more" of the enumerated components. It will be clear to one of ordinary skill in the art that the use of the singular includes the plural unless specifically stated otherwise. Therefore, the terms “a,” “an” and “at least one” are used interchangeably in this application.

[0067] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as size, weight, reaction conditions and so forth used in the specification and claims are to the understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present subject matter. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0068] Throughout the application, descriptions of various embodiments use "comprising" language; however, it will be understood by one of skill in the art, that in some instances, an embodiment can alternatively be described using the language "consisting essentially of or "consisting of."

[0069] The present subject matter being thus described, it will be apparent that the same may be modified or varied in many ways. Such modifications and variations are not to be regarded as a departure from the spirit and scope of the present subject matter, and all such modifications and variations are intended to be included within the scope of the following claims.

Claims

Claims1. Cooling apparatus to remove heat from a heat-generating electronic component immersed within a dielectric coolant liquid comprising: at least one heat-generating electronic component; at least one heat sink configured to receive thermal energy from a main face of the heat-generating electronic component and having a base and a plurality of heat transfer members each projecting from the base and terminating at respective terminal ends or edges, the members defining a least one side face of the heat sink extending between the base and the ends or edges, a terminal end face of the heat sink positioned opposed to the base and defined by terminal ends or edges; regions between the members defining flow ducts extending laterally across the heat sink between the base and the terminal end face; a support body having at least one mount region to receive and mount at least one rotor and an attachment region to attach the support body to the heat sink; at least one rotor rotatably mounted at the mount region; and at least one motor to drive rotation of the rotor at the support body and create at least one flow stream of the dielectric coolant liquid; wherein the support body is configured such that at least one rotor is positioned opposed to the at least one side face of the heat sink so as to direct the at least one flow stream through the flow ducts and laterally across the heat sink between the base and the terminal end face.

2. The apparatus as claimed in claim 1 wherein the heat sink is provided at the main face of the heat-generating electronic component.

3. The apparatus as claimed in claim 2 wherein the radiation members comprise a plurality of fins arranged in rows to define the liquid flow ducts extending between the fins, the fins and the base defining the heat sink as a generally block-shaped body.

4. The apparatus as claimed in claim 2 wherein the radiation members comprise a plurality of elongate pins or fingers projecting from the base to define the liquid flow ductsextending between the pins or fingers, the base and pins or fingers defining the heat sink as a generally block-shaped body.

5. The apparatus as claimed in claim 3 or 4 wherein the at least one rotor is positioned at the side face of the block-shaped body adjacent an entrance or exit end of the ducts.

6. The apparatus as claimed in claim 2 wherein the heat sink comprises a heat pipe, heat-transfer device comprising at least one first module to mount to the at least one heatgenerating electronic component; a heat spreader module connected to the first module in internal fluidic communication; and a liquid contained within the heat pipe heat-transfer device and configured to circulate between the first module and the heat spreader module and to undergo phase change within the device including an evaporation and condensation cycle.

7. The apparatus as claimed in claim 6 wherein the support body and the rotor are mounted at the heat spreader module.

8. The apparatus as claimed in any preceding claim wherein the heat-generating electronic component comprises any one or a combination of• an integrated circuit;• an integrated circuit chip;• a motherboard;• random access memory (RAM);• a graphics processing unit (GPU);• a central processing unit (CPU).

9. The apparatus as claimed in claim 8 wherein the at least one heat-generating electronic component is mounted at an electronic device comprising any one or a combination of• a computer entity;• a server;• a motherboard;• a printed circuit board comprising a plurality of electronic components;• an integrated circuit.

10. The apparatus as claimed in any preceding claim wherein the rotor mount region comprises at least one aperture to at least partially accommodate and allow rotation of the at least one rotor.

11. The apparatus as claimed in claims 1 or 2 wherein the rotor comprises not more than six blades or wherein the rotor comprises two to six, two to five, two to four or two or three blades projecting radially outward from a central boss.

12. The apparatus as claimed in any preceding claim wherein the rotor is a propeller or an impeller.

13. The apparatus as claimed in any preceding claim wherein the support body comprises a cover portion configured to sit over and about at least a part of the heat sink.

14. The apparatus as claimed in claim 13 wherein the cover portion is configured to sit over the main face of the heat-generating electronic component so as to prevent or inhibit flow of the dielectric coolant liquid through the main face.

15. The apparatus a claimed in any preceding claim wherein the rotor is positioned proximate and / or immediately adjacent the at least one side face of heat sink.

16. An immersion liquid cooling assembly comprising: the apparatus as claimed in any preceding claim; and a container defining a chamber to contain a dielectric coolant liquid and at least one electronic device immersed within the liquid, the electronic device mounting the at least one heat-generating electronic component.

17. The assembly as claimed in claim 16 wherein the electronic devices are arranged in a generally vertical orientation within the chamber such that a lengthwise first end of each electronic device is positioned closest to a trough of the chamber relative to a second lengthwise end of each electronic device positioned closest to upper region of the chamber; and wherein the cooling apparatus and in particular the rotor is positioned at or towards the first lengthwise end closest to the trough relative to the second lengthwise end of the electronic devices.

18. The assembly as claimed in claim 17 wherein the at least one rotor is positioned between the heat sink and a base face of the container that, in part, defines the trough of the chamber.

19. The assembly as claimed in any one of claims 16 to 17 comprising at least one liquid flow inlet and at least one liquid flow outlet provided at the container to allow a flow of the liquid to enter and exit respectively the chamber in direct contact with the electronic devices; and a cooling unit provided in fluidic communication with the chamber to cool the liquid and being provided in fluidic communication with at least one of said inlet and said outlet to form a fluid flow network to transfer heat energy from the heat-generating electronic components to the liquid.

20. The assembly as claimed in claim 19 further comprising a liquid flow pump connected in fluidic communication with the inlet and / or the outlet of the container to drive a flow of the liquid to and from the chamber.

21. The assembly as claimed in claim 19 or 20 wherein the cooling unit comprising a heat exchanger to transfer heat energy from the liquid to a heat transfer fluid.

22. A method of removing heat from a heat-generating electronic component comprising:immersing at least one heat-generating electronic component within a dielectric coolant liquid; providing at least one heat sink to receive thermal energy from a main face of the heat-generating electronic component, the heat sink having a base and a plurality of heat transfer members each projecting from the base and terminating at respective terminal ends or edges, the members defining a least one side face of the heat sink extending between the base and the ends or edges, a terminal end face of the heat sink positioned opposed to the base and defined by terminal ends or edges, wherein regions between the members defining flow ducts extending laterally across the heat sink between the base and the terminal end face; providing a support body having at least one mount region to receive and mount at least one rotor and an attachment region to attach the support body to the heat sink and position the rotor opposed to the at least one side face of the heat sink; creating a flow stream of the liquid through the flow ducts and laterally across the heat sink between the base and the terminal end face by driving rotation of the rotation of rotor at the support body.

23. The method as claimed in claim 22 wherein the container is an immersion tank containing a plurality of electronic devices each mounting at least one heat-generating electronic component, the electronic devices arranged in a generally vertical orientation within the chamber such that lengthwise ends of the devices are positioned closer to a trough region of the chamber relative to lengthwise second ends of the devices positioned closer to an open upper region of the chamber; wherein the rotor is positioned at or towards the first ends of the electronic devices; and wherein the fluid stream is directed generally upward in a liquid flow direction extending from the trough to the open upper region of the tank.

24. The method as claimed in claims 22 or 22 wherein the rotor is a propeller or an impeller.

25. The method as claimed in any of claims 22 to 24 wherein the cooling apparatus further comprises a rotor housing having at least one aperture to at least partially accommodate and allow rotation of the at least one rotor.

26. The method as claimed in claim 25 comprising creating a plurality of flow streams created using a plurality of rotors positioned respectively towards the first ends of the devices, each flow stream directed generally upward in a direction from the trough region to the open upper region of the tank.

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