Patent Application
20230225080
Integrated circuits contained within electronic devices, such as application specific circuits (ASICs), include ever-increasing numbers of transistors operating at ever-increasing frequencies. As a result, the power consumed by these integrated circuits increases accordingly, along with heat generated by the integrated circuits due to this increased power consumption. Heat transfer systems must accordingly be included in the electronic devices to transfer heat generated by these integrated circuits and maintain appropriate operating temperatures within the electronic device during operation. Various types of passive heat transfer technologies, which transfer heat away from the integrated circuit or other heat source, are commonly utilized to cool integrated circuits. These heat transfer technologies include thermosiphon systems, heat pipe systems, and vapor chamber systems. Each type of heat transfer system or heatsink has limitations as to the maximum amount of heat that may be transferred away from the integrated circuit.
As the power consumed by integrated circuits continues to increase, it is becoming increasingly more difficult to adequately cool integrated circuits using passive heat transfer technologies. Fluid heat transfer systems can transfer more heat than these types of passive heat transfer technologies and thus may be utilized instead to cool high-power integrated circuits. Fluid heat transfer systems are, however, typically more costly to manufacture and maintain and may increase power consumption of the electronic device, as well as increase risks in the event of a failure. Other active heat transfer or cooling systems utilizing fans or other air transfer devices may also be utilized to cool integrated circuits. Undesirably, these types of active cooling systems also will increase the power consumption of the electronic device including the integrated circuits.
There is a need for improved passive heat transfer techniques for cooling heat sources such as integrated circuits including ever-increasing numbers of transistors operating at ever-increasing frequencies.
With respect to the discussion to follow and in particular to the drawings, it is stressed that the particulars shown represent examples for purposes of illustrative discussion and are presented in the cause of providing a description of principles and conceptual aspects of the present disclosure. In this regard, no attempt is made to show implementation details beyond what is needed for a fundamental understanding of the present disclosure. The discussion to follow, in conjunction with the drawings, makes apparent to those of skill in the art how embodiments in accordance with the present disclosure may be practiced. Similar or same reference numbers may be used to identify or otherwise refer to similar or same elements in the various drawings and supporting descriptions.
Described in the present application are structures and techniques for passive hybrid heat transfer systems that improve the heat transfer capabilities of the system for better cooling heat sources such as integrated circuits in network devices. In the following description, for purposes of explanation, numerous examples and specific details are set forth in order to provide a thorough understanding of some embodiments. Some embodiments as defined by the claims may include some or all of the features in these examples alone or in combination with other features described below and may further include modifications and equivalents of the features and concepts described herein.
In embodiments of the present disclosure, a passive hybrid heat transfer system utilizes a thermosiphon heat transfer subsystem and a supplemental heat transfer subsystem that work in combination to transfer sufficient heat away from a heat source and thereby adequately cool the integrated circuit or other heat source. The supplemental heat transfer subsystem may, for example, be a heat pipe or vapor chamber heat transfer subsystem. The supplemental heat transfer subsystem is located in space around the thermosiphon heat transfer subsystem that is typically not utilized due to the physical constraints of a thermosiphon heat transfer subsystem. In a thermosiphon heat transfer subsystem, an evaporator is thermally coupled to a heat source and includes a condenser thermally coupled to the evaporator. The evaporator must be positioned below the condenser so that fluid in the condenser returns to the evaporator due to the force of gravity. As a result, the space under the evaporator relative to the direction of gravity may be unused or wasted in a thermosiphon heat transfer subsystem. Hybrid heat transfer systems according to some embodiments of the present disclosure utilize this space below the evaporator of a thermosiphon heat transfer subsystem by locating at least a portion of the supplemental heat transfer subsystem in this space. The supplemental heat transfer subsystem is thermally coupled to either the evaporator or the heat source and may include a portion extending below the evaporator relative to the direction of gravity. This enables the supplemental heat transfer subsystem to transfer additional heat away from the heat source. In operation, the thermosiphon heat transfer subsystem and supplemental heat transfer subsystem operate together to transfer sufficient heat away from the heat source to adequately cool the heat source during its operation.
SHS 108 may be any of a variety of different types of passive heat transfer technologies such as a heat pipe heat transfer subsystem, a vapor chamber heat transfer subsystem, or any passive heat sink subsystem having a structure configured to maximize a surface area of the structure in contact with a surrounding cooling medium. The location or position of SHS 108 takes advantage of normally unused space 110 below evaporator 106 of thermosiphon heat transfer subsystem 102. This space 110 is normally unused due to the way in which thermosiphon heat transfer subsystem 102 operates in relying on gravity g to return a condensed fluid in condenser 104 to evaporator 106, as will be described in more detail below. One skilled in the art will understand suitable materials such as aluminum, copper, and other thermally conductive materials to form the SHS 108.
The operation and structure of thermosiphon heat transfer subsystem 102 will now be described in more detail to better understand advantages of the structure of hybrid heat transfer system 100. One skilled in the art will understand the operating principles and physical structure of thermosiphon systems, and thus these principles and structures will only be described to the extent necessary to enable one skilled in the art to understand the structure and advantages of hybrid heat transfer system 100. Thermosiphon heat transfer subsystem 102 contains a suitable working fluid such as water, ethanol, refrigerants (e.g., R134), or methanol, for example, with the specific working fluid being chosen based on the required temperatures at which the thermosiphon system must operate. One skilled in the art will understand suitable materials, such as aluminum, copper, and other thermally conductive materials, to form the components of thermosiphon heat transfer subsystem 102.
In operation, heat from heat source 112 is supplied to evaporator 106 and in response to this heat, the working fluid in the evaporator is vaporized and exits the top of the evaporator through vapor tube 114. The vaporized working fluid exits evaporator 106 and travels upward through vapor tube 114 to condenser 104. The upward dashed arrow in vapor tube 114 in
Because thermosiphon heat transfer subsystem 102 relies on the force of gravity g to return the liquidized working fluid in condenser 104 to evaporator 106 via the fluid return tube 116, the condenser must be positioned above the evaporator relative to the direction of gravity. In
Due to the reliance on the force of gravity g in thermosiphon systems such as the thermosiphon heat transfer subsystem 102, space 110 below evaporator 106 in the direction of the force of gravity g (i.e., along the direction of gravity g or parallel to the Y-axis) is not utilized by the thermosiphon heat transfer subsystem. This is true because if any portion of fluid return tube 116 were to be positioned below evaporator 106, then thermosiphon heat transfer subsystem 102 would need to include some means of returning the liquidized working fluid in this portion of the fluid return tube upward against the force of gravity g to the evaporator.
In hybrid heat transfer system 100, SHS 108 includes heat dissipation portion 109 that extends into space 110 not utilized by thermosiphon heat transfer subsystem 102. In this way, SHS 108 utilizes this unused space and also provides additional heat transfer capacity for hybrid heat transfer system 100 to help transfer heat away from and thereby help cool heat source 112. In the example embodiment of
Heat source 112, SHS 108 and evaporator 108 may be attached in different arrangements or configurations so long as at least a portion 109 of SHS 108 is positioned in space 110 below the evaporator. In the example embodiment of
In hybrid heat transfer system 200, evaporator 206 includes a lower surface to which the attachment portion 218 of SHS 208 is attached. Thus, the entire SHS 208 is positioned under or extends below evaporator 206 relative to the direction of gravity g, which is shown parallel to the Y axis. Both attachment portion 218 and heat dissipation portion 209 of SHS 208 are positioned below evaporator 206 along the direction of gravity g in hybrid heat transfer system 200. SHS 208 is in this way thermally coupled to evaporator 206 and operates in combination with the evaporator of thermosiphon heat transfer subsystem 202 to transfer heat away from and thereby cool heat source 212.
In operation of the vapor chamber device 508, the vapor chamber device includes a hot interface (attachment portion 518) at which the vapor chamber is thermally coupled to evaporator 506 causing a fluid in the heat pipe to absorb heat from a thermally conductive solid surface of the heat pipe and to turn into a vapor. This vapor travels through the vapor chamber device 508 to a cold interface (dissipation portion 509) of the vapor chamber and condenses back into a liquid, releasing the latent heat and in this way removing heat from evaporator 506. The condensed liquid at the cold interface (dissipation portion 509) then returns through capillary action against the force of gravity g to the hot interface (attachment portion 518). In this way, vapor chamber device 508 helps cool evaporator 506 and thereby heat source 512.
Hybrid heat transfer system 500 further includes a plurality of heat sinks 520, 522, and 524 configured to be attached to the upper side surface of condenser 504 of thermosiphon heat transfer subsystem 502. Each heat sink 520-524 is formed from a suitable thermally conductive material or materials, such as aluminum and copper, and has a structure to dissipate heat from condenser 504 generated during operation of thermosiphon heat transfer subsystem 502. For example, each heat sink 520-524 may include a base configured to be attached to condenser 504 and having a plurality of fins extending from the base. This type of structure increases the surface area of heat sinks 520-524 to thereby increase heat dissipating capacity, as will be appreciated by those skilled in the art. Similarly, a plurality of heat sinks 526-530 are configured to be attached to the upper side surfaces of SHS 508 and evaporator 506. More specifically, heat sinks 526 and 528 are attached to the upper side surface of SHS 508 while heat sink 530 is attached to a portion of the upper side surface of evaporator 506 that is not covered by attachment portion 518 of SHS 508. Each heat sink 526-530 is also formed from a suitable thermally conductive material and has a suitable structure to dissipate heat from SHS 508 and the evaporator 506.
Network device 600 is a switch or a router, for example, and may also be another type of network device in further embodiments of the present disclosure. Network device 600 includes management module 616, internal fabric module 618, and a number of I/O modules 620a-620p. Management module 616 may be a part of control plane 602, which may also be referred to as control layer, of network device 600 and can include one or more management CPUs 622 for managing and controlling operation of network device 600. Each management CPU 622 can be a general-purpose processor, such as an Intel®/AMD® x86-64 or ARM® processor, operating under the control of software stored in memory, such as storage subsystem 624, which may include read-only memory and/or random access memory.
In some embodiments, CPU 622 may include control circuitry, and may include or be coupled to a non-transitory storage medium storing encoded instructions that cause the CPU to perform desired operations during operation of network device 600. In some embodiments, the non-transitory storage medium may include encoded logic or hardwired logic for controlling operation of CPU 622. Control plane 602 refers to all the functions and processes that determine paths to be used, such as routing protocols, spanning tree, and the like, during operation of the network device 600. Management module 616 and ASIC in control plane 602 include the functional components needed to manage traffic forwarding features of network packets being received by the network device 600. These forwarding features would typically include routing protocols, configuration information and other similar functions that determine the destinations of network packets based on information other than the information contained within these network packets.
Internal fabric module 618 and I/O modules 620a-620p collectively represent a data plane 626 of the network device 600, with the data plane also commonly being referred to as a data layer or a forwarding plane. Data plane 626 is configured by control plane 602 and includes all the functional components needed to perform forwarding operations for network packets received via I/O modules 620a-620p on ingress ports and outputting these network packets via I/O modules on egress ports. Internal fabric module 618 is configured to interconnect I/O modules 620a-620p of network device 600. Each I/O module 620a-620p includes one or more input/output ports 628a-628p that are used by network device 800 to send and receive network packets over communication links (not shown) coupled to the ports. Each I/O module 620a-620p may also include a packet processor 630a-630p. Each packet processor 630a-630p may include forwarding hardware circuitry configured to make wire speed decisions on the processing of incoming (ingress) and outgoing (egress) network packets being communicated over communication links (not shown) coupled to ports 628a-628p. In some embodiments, the forwarding hardware circuitry may include an application specific integrated circuit (ASIC), a field programmable array (FPGA), a digital processing unit, or other suitable structures of configured logic.
The drawings are representative and suggestive of geometries in various described embodiments of hybrid heat transfer systems according to the present disclosure but are not necessarily to scale. The specific shapes of the various components forming hybrid heat transfer systems according to embodiments of the present disclosure may vary in alternative embodiments. Moreover, the specific orientations of any of the described embodiments of hybrid heat transfer systems of
In various embodiments, the present disclosure includes systems and methods of hybrid passive heat transfer and network devices including hybrid passive heat transfer systems.
In one embodiment, a hybrid heat transfer system, comprises: a thermosiphon heat transfer subsystem including a condenser coupled to an evaporator, the evaporator configured to be coupled to a heat source and positioned below the condenser relative to a direction of gravity; and a supplemental heat transfer subsystem thermally coupled to the evaporator of the thermosiphon heat transfer subsystem, the supplemental heat transfer subsystem including at least a portion extending below the evaporator relative to the direction of gravity.
In an embodiment of the hybrid heat transfer system, the supplemental heat transfer subsystem comprises a heat pipe heat transfer subsystem.
In an embodiment of the hybrid heat transfer system, the supplemental heat transfer subsystem comprises a vapor chamber heat transfer subsystem.
In an embodiment of the hybrid heat transfer system, the evaporator includes a first surface configured to be attached to the heat source and includes a second surface opposite the first surface attached to the supplemental heat transfer subsystem.
In an embodiment of the hybrid heat transfer system, the evaporator is thermally coupled through the supplemental heat transfer subsystem to a heat source.
In an embodiment of the hybrid heat transfer system, the supplemental heat transfer subsystem includes an attachment portion thermally coupled to the first surface of the evaporator and includes a heat dissipation portion extending below the attachment portion and the evaporator relative to the direction of gravity.
In an embodiment of the hybrid heat transfer system, the evaporator includes a lower surface configured to be coupled to the supplemental heat transfer subsystem extending entirely below the evaporator relative to the direction of gravity.
In an embodiment of the hybrid heat transfer system, the condenser of the thermosiphon heat transfer subsystem further comprises heat fins to dissipate heat.
In an embodiment of the hybrid heat transfer system, the supplemental heat transfer subsystem further comprises heat fins to dissipate heat.
In a further embodiment, a hybrid heat transfer system, comprises: a thermosiphon heat transfer subsystem including a condenser coupled to an evaporator, the evaporator having a structure to be coupled to a heat source and being positioned below the condenser along a direction of gravity; and a supplemental heat transfer subsystem thermally coupled to the evaporator of the thermosiphon heat transfer subsystem to remove heat generated by the heat source, at least a portion of the supplemental heat transfer subsystem positioned below the evaporator along the direction of gravity.
In an embodiment of the hybrid heat transfer system, the supplemental heat transfer subsystem comprises at least one of a heat pipe heat transfer subsystem or a vapor chamber heat transfer subsystem.
In an embodiment of the hybrid heat transfer system, the evaporator includes a first surface to be attached to the heat source and includes a second surface opposite the first surface attached to the supplemental heat transfer subsystem.
In an embodiment of the hybrid heat transfer system, the supplemental heat transfer subsystem includes an attachment portion and a heat dissipation portion, the attachment portion including a first surface attached to the evaporator and including a second surface opposite the first surface to be attached to the heat source.
In an embodiment of the hybrid heat transfer system, the evaporator includes a lower surface relative to the direction of gravity and wherein the supplemental heat transfer subsystem is attached to the lower surface and is positioned entirely below the evaporator relative to the direction of gravity.
In an embodiment of the hybrid heat transfer system, the condenser includes a first surface and wherein thermosiphon heat transfer subsystem further comprises at least one heat sink attached to the first surface of the condenser.
In an embodiment of the hybrid heat transfer system, the condenser further includes a second surface opposite the first surface, and wherein the thermosiphon heat transfer subsystem further comprises at least one heat sink attached to the second surface of the condenser.
In an embodiment, the hybrid heat transfer system further comprises at least one heat sink attached to the thermosiphon heat transfer subsystem.
In yet another embodiment, a network device, comprises: a data plane to forward network packets from an ingress port to an egress port; a control plane to configure the data plane, the control plane including: an integrated circuit; and a hybrid heat transfer system coupled to the integrated circuit to cool the integrated circuit during operation of the network device, the hybrid heat transfer system including: a thermosiphon heat transfer subsystem including a condenser coupled to an evaporator, the evaporator attached to the integrated circuit and positioned below the condenser relative to a direction of gravity; and a supplemental heat transfer subsystem thermally coupled to the evaporator of the thermosiphon heat transfer subsystem, the supplemental heat transfer subsystem including at least a portion extending below the evaporator relative to the direction of gravity.
In an embodiment of the network device, the supplemental heat transfer subsystem comprises one of a heat pipe heat transfer subsystem and a vapor chamber heat transfer subsystem.
In an embodiment of the network device, the network device comprises one of a network router and a network switch.
The above description illustrates various embodiments along with examples of how aspects of some embodiments may be implemented. The above examples and embodiments should not be deemed to be the only embodiments and are presented to illustrate the flexibility and advantages of some embodiments as defined by the following claims. Based on the above disclosure and the following claims, other arrangements, embodiments, implementations and equivalents may be employed without departing from the scope of the present disclosure.
