Patent Application
20050241802
Electronic systems and equipment such as computer systems, network interfaces, storage systems, and telecommunications equipment are commonly enclosed within a chassis, cabinet or housing for support, physical security, and efficient usage of space. Electronic equipment contained within the enclosure generates a significant amount of heat. Thermal damage may occur to the electronic equipment unless the heat is removed.
As electronic components and subsystems evolve to increasing capability, performance, and higher power, while reducing size and form factor, efficient and cost-effective removal of excess heat is desired. Among available thermal management solutions, liquid cooling via cold plate technology offers high capacity for heat rejection and movement of heat from internal sources to external ambient air. Liquid cooling loop systems typically cycle pumped coolants continuously, conveying excess heat from heat-generating devices. The heat is dispersed into ambient air using a heat exchanger or other device.
In accordance with an embodiment of an electronic liquid cooling system, an assembly includes a heat exchanger with a tube and a plurality of fins coupled to the tube, and a mount coupled to the heat exchanger capable of attaching a variable number and configuration of fans to the heat exchanger.
Embodiments of the invention relating to both structure and method of operation, may best be understood by referring to the following description and accompanying drawings.
Compact electronic devices and systems, such as server architectures, may use a liquid loop cooling solution to accommodate increasing power and power density levels for microprocessors and associated electronics. Liquid loops can use a pump to drive cooling fluid through high pressure-drop channels of the colds plates attached to processors and other high-power components and along potentially long and narrow-diameter tube completing the loop between the cold plate, condenser, and pump. Heat is removed from the loop by forced-air convection at the condenser.
A disclosed electronic liquid cooling system includes a redundant fan configuration to increase reliability, thereby eliminating the weakness of a single point-of-failure implementation.
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In the various embodiments of the assembly 102, 122, a sufficiently large number of fans 112 can be mounted to the heat exchanger 104 to exceed system cooling specifications, enabling less expensive and less reliable fans to be used while retaining high reliability.
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The electronic liquid cooling system 124 further includes a plurality of cold plates 128 coupled to the tubing 126 and capable of addition and removal via quick disconnect connectors 130. A typical example of a cold plate 128 is a flat metal plate with a series of channels on one or both sides. A length of serpentine tubing can be secured within the channels to contain the liquid coolant flows. Fittings at the inlet and outlet of the tubing connect to the tubing 126. Common tubing materials are copper and stainless steel. Components may be mounted on one or both sides of a cold plate 128.
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The number and arrangement of heat sources, for example heat-generating components 206, may be varied in different electronic system configurations. The flexible electronic liquid cooling system 208 enables variation of the number of cooling fans 218 for condenser or heat exchanger cooling. In the illustrative system, a varying number of fans 218 can be allocated in association with a particular heat exchanger 212.
The electronic liquid cooling system 208 may further include one or more mounts 220 coupled to the heat exchanger 212 that can attach a variable number and configuration of fans 218 to the heat exchanger 212. One or more cold plates 222 can be coupled to the tubing 210 to facilitate addition and removal via quick disconnect connectors 224.
The illustrative electronic system 200 and electronic liquid cooling system 208 can be arranged with multiple various fan configurations to attain a lower cost and/or enable upgrading to liquid loop cooling capabilities. The electronic system 200 and electronic liquid cooling system 208 can be designed by determining thermal conditions within the electronic system 200. Airflow patterns within the chassis 202 may be determined according to sizes and positioning of devices and components 206 and other internal obstructions. Coolant flow patterns within the tubing 210 is also determined including analysis of sizing of individual components 206 and cold plates 222 to enable a selected flow to be delivered to cold plates 222 and any heat sinks onto which electronic components 206 may be mounted. Analysis of the liquid loop may also take into consideration the arrangements of the tubing 210 and tubes 214 in the heat exchangers 212 as well as impact on flow of any junctions or quick disconnects 224 coupled to the tubing 210. The thermal conditions also vary depending on heat generated by particular components 206 and transfer to cooling plates 222.
The method for electronic liquid cooling system design further includes configuring the liquid loop cooling system 208 with one or more heat exchangers 212 associated with a plurality of fans 218. The number and positioning of the fans 218 is selected to be at least one higher than a minimum to meet cooling specifications based on the thermal conditions.
In some applications, the liquid loop cooling system 208 may be populated with multiple lower-cost, lower-reliability fans in a number sufficiently high that more than one fan may fail while maintaining cooling system integrity.
The electronic liquid cooling system 208 may be designed for redundancy, for example for N+1 fans when N fans are sufficient to meet cooling specifications. Customers or those configuring systems on the basis of minimum cost and who are not willing to pay extra for redundancy may arrange a system with redundant fans eliminated, resulting in a lower system cost. A customer can purchase a system with N cooling fans for a low entry price point.
The flexible fan configuration enables an initial design of the liquid loop cooling solution that is oversized. Fewer fans or lower performance fans can be initially installed to lower costs while meeting initial heat loads. Subsequent system upgrades, for example to higher power processors, are accommodated by adding fans or replacing initially-installed low-cost fans with faster, higher-performance fans. The flexible system thus enables low initial cost and supports flexible upgrading that can substantially improve cooling performing without change to installed cold plates 222.
The oversized liquid loop can support a wide range of numbers of cold plates 222 and heat sources, and support a high degree of modification flexibility through usage of quick disconnects, facilitating removal and addition of heat sources and cold plates.
In other applications, the electronic system 200 and/or electronic liquid cooling system 208 may be designed to accommodate many small, low-cost fans with lower reliability in such a way that more than one fan may fail without impacting integrity of the cooling solution. The configuration may enable a lower overall material cost relative to the use of larger, more reliable and costly fans. Flexibility of heat exchanger geometry may be exploited to enable additional fan arrangements.
The flexible fan arrangement enables a liquid loop configuration with additional cooling capacity than is necessary for a first release of a particular electronic system, such as a server. Fan slots adjacent the heat exchanger 212 may not be fully loaded in a first release to enable a lower initial cost. Upgrades to higher power devices and components, such as higher performance processors, are accommodated by adding fans to the open slots or replacing existing fans with higher performance models. The flexibility enabled by the disclosed arrangement of compact heat exchangers, liquid cooling, and variable arrangement of fans may be difficult to attain in traditional air-cooled heat sink designs.
As an electronic system 200 is upgraded by modifying the electronic component combination, the configuration of fans may also be modified based on changed thermal conditions due to the electronic component combination modification.
The illustrative heat exchanger 212 and tubing 210 can be configured for usage in multiple platforms and with multiple heating sources. Varying numbers of heat sources can be added or removed using quick disconnects 224. Varying cooling criteria and form factors are accommodated through usage of a wide range of numbers and sizes of cooling fans 218. The basic components of the electronic liquid cooling system 208 can be arranged in various configurations and in differing numbers, sizes, and performance characteristics across multiple platforms, resulting in lower manufacturing costs through larger volumes, fewer parts in the field, and the like.
A condenser is typically a compact heat exchanger 212 constructed of the fins 216 attached to the tube 214 containing the cooling fluid. The tube 214 may pass through the fin bank 216 many times and in various orientations to attain optimized cooling performance.
Multiple fan configurations are associated with the different heat exchanger configurations to enable flexible cooling capabilities.
In a compact server, cooling air is driven across a heat exchanger using common tube-axial or blower fans. Liquid loops enable a high degree of flexibility regarding dimensions of the heat exchanger. The heat exchangers may be sized to fit the width of a single fan or span the width of several fans arranged side-by-side. Heat exchanger designs that accommodate multiple fans may enable redundant fan cooling solutions. For example, one of the fans may fail and the remaining fans supply sufficient cooling air flow to meet component temperature requirements.
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While the present disclosure describes various embodiments, these embodiments are to be understood as illustrative and do not limit the claim scope. Many variations, modifications, additions and improvements of the described embodiments are possible. For example, those having ordinary skill in the art will readily implement the steps necessary to provide the structures and methods disclosed herein, and will understand that the process parameters, materials, and dimensions are given by way of example only. The parameters, materials, and dimensions can be varied to achieve the desired structure as well as modifications, which are within the scope of the claims. Variations and modifications of the embodiments disclosed herein may also be made while remaining within the scope of the following claims. For example, although particular geometries of the redundant fan and heat exchanger arrangements are shown, other arrangements are possible including additional multiple-pass arrangements in which additional fans, heat exchanger geometries, and heat exchanger segments are added. Also, particular electronic system embodiments are illustrated, for example a computer server. In other embodiments, the external heat exchanger can be employed in other types of electronic systems such as communication systems, storage systems, entertainment systems, and the like.
