Patent Application
20090225514
The invention relates to a method of and apparatus for cooling a heat producing device in general, and specifically, to a method of and apparatus for cooling server applications using fluid-based cooling systems.
Cooling of high performance integrated circuits with high heat dissipation is presenting significant challenge in the electronics cooling arena. Conventional cooling with heat pipes and fan mounted heat sinks are not adequate for cooling chips with ever increasing wattage requirements, including those exceeding 100 W.
Electronics servers, such as blade servers and rack servers, are being used in increasing numbers due to the higher processor performance per unit volume one can achieve. However, the high density of integrated circuits also leads to high thermal density, which is beyond the capability of conventional air-cooling methods.
A particular problem with cooling integrated circuits on electronics servers is that multiple electronics servers are typically mounted in close quarters within a server chassis. In such configurations, electronics servers are separated by a limited amount of space, thereby reducing the dimensions within which to provide an adequate cooling solution. Typically, stacking of electronics servers does not provide the mounting of large fans and heat sinks for each electronics server. Often electronics server stacks within a single server chassis are cooled with one or more fans, one or more heat sinks, or a combination of both. Using this configuration, the integrated circuits on each electronics server are cooled using the heat sink and the large fan that blows air over the heat sink, or simply by blowing air directly over the electronics servers. However, considering the limited free space surrounding the stacked electronics servers within the server chassis, the amount of air available for cooling the integrated circuits is limited.
As data centers continue to increase their computer density, electronics servers are being deployed more frequently. Fully populated electronics servers significantly increase rack heat production. This requires supplemental cooling beyond what the Computer Room Air Conditioning (CRAC) units can provide. Supplemental cooling systems may include fans, pumps, and heat exchangers located outside the back end of the electronics server to decrease the air temperature exiting the electronics server. The heat exchangers in these supplemental cooling systems are supplied with pumped coolants, water, or refrigerants. While these supplemental cooling systems can take advantage of efficiency gained by economies of scale, they still require additional fans. It is desirable to take advantage of the existing fans in the electronics server.
Some supplemental cooling systems are configured as a “cooling door” that is attached to the back of a server rack. Supply and return hoses extend into the data center floor through a large opening. This large opening is required to provide clearance so that additional hose length can be pulled out of the floor as the door is opened and slid back into the floor when the door is closed. The space in the floor is usually under a positive pressure with air being supplied from CRAC units. The floor opening can cause a loss in efficiency as some amount of chilled air escapes from under the floor through this opening. Further, pulling additional hose out of and sliding the hose back into the opening is a tedious, and sometimes difficult, activity for the user opening and closing the cooling door. Still further, since the hose is connected to the cooling door as the door is opened and closed, physical strain is placed on the cooling door and hose connection, which creates wear and tear on, and possibly damage to, the connection components.
Cooling systems of the present invention are directed to a cooling door assembly including one or more heat exchangers. The cooling door assembly includes a frame and a cooling door coupled to the frame. The frame is configured to mount to a server rack, cabinet, or other electronics enclosure in such a manner that the cooling door opens to allow access to the electronics servers within the server rack while maintaining a fluidic connection to an external cooling system. The cooling door and frame are mounted together to form a stand-alone cooling door assembly with input and output plumbing to the external cooling system. There is no plumbing within the server rack and therefore the cooling door assembly does not include plumbing into and out of the server cabinet. As such, there is no need to modify an existing server cabinet for plumbing when adding the cooling door assembly to the server cabinet. The cooling door assembly is configured as a retrofit assembly to the server cabinet. The frame of the cooling door assembly can be designed to mate to different sized server cabinets. The frame is coupled to the external cooling system, and the cooling door includes one or more swivel joints configured to provide a fluid path between the cooling door and the frame. In this manner, the frame remains in a fixed position, while the cooling door is configured to rotate relative to the frame so as to open and close, while maintaining the fluid path through each swivel joint.
The cooling door assembly does not include hoses that are pulled in and out of the floor when the cooling door is opened and closed. The cooling door assembly can be hard plumbed or virtually hard plumbed since the use of highly flexible hoses is no longer used as a connection to an external cooling system. In addition, since highly flexible hoses are no longer used, metal tubes and pipes can be used, which allows for the use of refrigerants, such as R-134. With the use of refrigerant, an increase in cooling capacity can be obtained.
In some embodiments, the frame includes mounting blocks that are coupled with external fluid connectors for supplying and returning coolant from an external source, such as an external cooling system. The external cooling system can include a cooling tower, a chiller, or other secondary cooling loop including a heat exchanger used to cool the coolant exiting the cooling door assembly. Water, refrigerant, or any other coolant is used. In some embodiments, the coolant is a two-phase coolant. In other embodiments, the coolant is a single-phase coolant. Fluid flow rate controls can be included to optimize the coolant flow rate within the cooling door assembly. In some embodiments, the fluid flow rate controls are implemented using flow rate valves under the control of a control module.
The mounting blocks, including a supply mounting block and a return mounting black, are each configured using one of a number of various connection types, and with one or more input/output openings. For example, the supply mounting block can have 1, 2, or more input connections depending on the amount of coolant that is required. The same can be done on the return mounting block. The connection types can be a flare fitting, a threaded connection, or other common types of connection. In a two-phase system, there is an extra pressure drop that occurs when a fluid is in the gas phase. In this case, the cooling door assembly can be configured to have a supply mounting block with a single input coupled to a single coolant supply line, and a return mounting block with multiple outputs coupled to multiple return lines, for example. If the connection type has too high a fluid pressure drop, then the mounting blocks can be configured with multiple supply or return connections. The frame including the mounting blocks is designed such that the mounting blocks are interchangeable so that different connection types and number of connections are readily available by simply switching mounting blocks.
In some embodiments, both the supply mounting block and the return mounting block are located at the top of the frame. In other embodiments, the mounting blocks are located at the bottom of the frame, such as when a chilled water loop is used. It is also possible to position the mounting blocks in a configuration such that one is at the top and one is at the bottom. In some configurations, one or more mounting blocks are located at the top of the frame and one or more mounting blocks are located at the bottom of the frame. This may be the case if the system is coupled to one or more different cooling loops in order to provide redundancy in case of failure. The mounting blocks are designed to add minimal pressure drop to the system.
The mounting blocks are fixed in position relative to the frame. The cooling door is rotatably coupled to the frame through the use of coolant swivel joints, also referred to as rotary unions. The swivel joint allows fluid to pass through a hinge that allows rotation to occur and also provides a fluid path between the fixed mounting block and the rotating cooling door. A swivel joint is coupled to at least one of the mounting blocks. In some embodiments, the swivel joint is configured with a single fluid path. In other embodiments, the swivel joint is configured with multiple fluid paths. Multiple load-bearing mechanical hinges are used to attach the cooling door to the frame.
A heat exchanger system on the cooling door is configured to transfer heat from the air passing over the heat exchanger surfaces into the coolant flowing within the heat exchangers. The heat exchangers are designed with a low airflow impedance. This allows the existing air movers in the electronics enclosure to be used to provide the air flow for cooling. Optionally, a separate fan tray is attached to the cooling door to provide better air flow.
In some embodiments, the heat exchangers are made of a micro-tube construction with attached air fins or of a tube-fin type of design. The cooling door can include a single large heat exchanging panel or a group of heat exchanging panels attached in parallel or series. Separate heat exchanging panels are more manageable to construct and provide better control of fluid distribution. In some embodiments, each heat exchanging panel has its own separate flow regulator or valve for regulating the amount of coolant flow within the panel. The regulators or valves can be set so that each panel gets equal coolant flow or each panel gets a different amount of coolant. In other embodiments, a flow control regulator is positioned at any point on the fluid supply side of the heat exchanging panels, such as in a frame supply line or a cooling door supply line.
The system of heat exchanging panels can be oriented so that coolant flow is either in the horizontal orientation or the vertical orientation. When the heat exchanging panels are arranged in the vertical orientation, coolant enters at the bottom-most heat exchanging panel and flows upward. This configuration ensures that as much fluid as possible is in the cooling door. Separate panels also enable one or more windows to be included in the cooling door. Heat exchangers are difficult to see through. By breaking up the cooling door into a series of panels, one or more windows can be added in between the heat exchangers so that one can see into the enclosure. This is particularly useful to see warning lights. Each window is covered with a transparent material so as to prevent airflow through the window opening.
The multiple heat exchanging panels are coupled to each other either in series, in parallel, or a series-parallel combination via mounting piping to make a rigid assembly. In order for the cooling door to properly open and close without binding, the mechanical hinges and the swivel joints optimally have all their axis of rotation co-linear. If the axis are not collinear, then some amount of flex is required to prevent binding. To accomplish this, flexible tubing is used in key areas on the cooling door. This allows for some flex and misalignment to be taken up. Flexible tubing or flexible piping generally has better bending flex than it has the ability to torsionally flex (twist) or axially flex (longer or shorter.) To overcome this, sections of flexible piping are assembled together with a non-flexible right-angle bend. The non-flexible right-angle bend allows one arm to move axially because the movement is taken up be a bend in flexible tubing coupled to the other arm. Both flexible members allow flex in three-dimensions. An alternative way of accomplishing this is by using a four-bar linkage. The four bar linkage allows for movement of the swivel joint without changing the rotational orientation of the swivel joint.
Other features and advantages of the present invention will become apparent after reviewing the detailed description of the embodiments set forth below.
The present invention is described relative to the several views of the drawings. Where appropriate and only where identical elements are disclosed and shown in more than one drawing, the same reference numeral will be used to represent such identical elements.
Reference will now be made in detail to the embodiments of the cooling system of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the embodiments below, it will be understood that they are not intended to limit the invention to these embodiments and examples. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to more fully illustrate the present invention. However, it will be apparent to one of ordinary skill in the prior art that the present invention may be practiced without these specific details. In other instances, well-known methods and procedures, components and processes haven not been described in detail so as not to unnecessarily obscure aspects of the present invention.
Embodiments of the present invention are directed to a cooling system that transfers heat generated by one or more electronics servers within a server rack. The cooling system described herein can be applied to any electronics sub-system that is mounted to a backplane, including but not limited to, a blade server and a rack server, herein referred to collectively as an electronics server. A server chassis is configured to house multiple electronics servers. Each electronics server is coupled to a backplane or mid-plane within the server chassis. Each electronics server includes one or more heat generating devices as is well known in the art.
One or more external supply lines 20 provide coolant from an external source, such as an external cooling system, to the cooling door assembly 10 via a supply mounting block 16 within the frame 12. As shown in
A flex assembly 38 is coupled to the swivel joint 28, and a cooling door supply line 40 is coupled to the flex assembly 38. A heat exchanging panel 8 is coupled to the cooling door supply line 40 via a panel supply line 42. The heat exchanging panel 8 is also coupled to a cooling door return line 58 via a panel return line 50. A heat exchanging panel 6 is coupled to the cooling door supply line 40 via a panel supply line 44. The heat exchanging panel 6 is also coupled to the cooling door return line 58 via a panel return line 52. A heat exchanging panel 4 is coupled to the cooling door supply line 40 via a panel supply line 46. The heat exchanging panel 4 is also coupled to the cooling door return line 58 via a panel return line 54. A heat exchanging panel 2 is coupled to the cooling door supply line 40 via a panel supply line 48. The heat exchanging panel 2 is also coupled to the cooling door return line 58 via a panel return line 56. Each heat exchanging panel includes a fluid input header and a fluid output header. The fluid input header is configured with one or more fluid input ports, and the fluid output header is configured with one or more fluid output ports. The panel supply line for each heat exchanging panel is coupled to the corresponding fluid input header, and the panel return line for each heat exchanging panel is coupled to the corresponding fluid output header. Where the fluid input header includes multiple fluid input ports, either a single common panel supply line is coupled to the multiple fluid input ports, or a separate panel supply line is coupled from the cooling door supply line to each of the fluid input ports. Where the fluid output header includes multiple fluid output ports, either a single common panel return line is coupled to the multiple fluid output ports, or a separate panel return line is coupled from each of the fluid output ports to the cooling door return line. The cooling door 14 is configured such that coolant flow through each of the heat exchanging panels 2, 4, 6, 8 is from bottom to top. Such a configuration provides a more consistent and uniform coolant flow through the heat exchanging panels than a top to bottom coolant flow configuration.
The cooling door return line 58 is coupled to a flex assembly 36, and the flex assembly 36 is coupled to a swivel joint 30. The swivel joint 30 is coupled to one or more external return lines 22 via a return mounting block 18. As shown in
The cooling door assembly 10 shown in
The cooling door 14 is coupled to the frame 12 using a plurality of mechanical hinges 32, 34. The mechanical hinges 32, 34 are configured as load-bearing connection points and are also configured to enable the cooling door 14 to rotate relative to the frame 12. Although two mechanical hinges 32 and 34 are shown in
Each swivel joint 28, 30 is configured to enable the cooling door 16 to rotate relative to the frame 12, and in particular relative to the mounting block 18 and the frame supply line 26, while maintaining a sealed fluid path between the frame 12 and the cooling door 14.
In operation, coolant is provided to the supply mounting block 16 via the external supply lines 20. The coolant flows through the supply mounting block 16, through the frame supply lines 24 and 26 and to the cooling door 14 via the swivel joint 28. Coolant flows from the swivel joint 28 through the flex assembly 38 to the cooling door supply line 40. Coolant is provided to each of the heat exchanging panels 2, 4, 6, 8 from the cooling door supply line 40 via the panel supply lines 48, 46, 44, 42, respectively. Coolant flows through each of the heat exchanging panels 2, 4, 6, 8 to the panel returns lines 56, 54, 52, 50, respectively, and into the cooling door return line 58. Coolant flows from the cooling door return line 58 through the flex assembly 36 to the swivel joint 30 and into the return mounting block 18. Coolant is output from the cooling door assembly 10 to the external return lines 22 via the return mounting block 18. Air from inside the electronics enclosure 80 is directed out of the enclosure through each of the heat exchanging panels 2, 4, 6, 8 within the cooling door 14. As air passes through each of the heat exchanging panels 2, 4, 6, 8, and over the heat exchanging surfaces of the heat exchanging panels 2, 4, 6, 8, heat is transferred from the air to the coolant flowing through the heat exchanging panels 2, 4, 6, 8. The heated coolant is then output from the cooling door assembly 10 to an external cooling system via the external return lines 22, where the coolant is cooled and returned to the cooling door assembly 10 via the external supply lines 20.
The return mounting block 18 shown in
In some embodiments, each of the panel supply lines 42, 44, 46, and 48 include a flow control regulator or valve. As shown in
As shown in
The active system includes one or more of a fan tray, airflow guides, one or more air movers, one or more thermal sensors, one or more anemometers, and a control module. The air flow guides are configured to guide cooling air in a defined manner. The one or more air movers, such as fans, are either fixed or variable speed. The one or more thermal sensors and the one or more anemometers are positioned in the airstream prior to the one or more heat exchangers and/or in the airstream after the one or more heat exchangers. The one or more anemometers measure the rate of airflow and the one or more thermal sensors measure the temperature. The control module is configured to use data received from the one or more thermal sensors and/or the one or more anemometers to adjust the fan speeds into favorable performance zones, thereby increasing efficiency of the system. The system can also be configured such that the control module controls the coolant flow rate by controlling the flow control regulators or valves.
The cooling door assembly shown in
The cooling door assembly 110 is also configured to operate within a two-phase cooling system. In such a system, coolant input to the cooling door assembly 110 is in a liquid phase, and the coolant output from the cooling door assembly 110 is in a gas phase or a combination of liquid and gas phase. The coolant in the cooling door assembly 110 remains in the liquid phase until it enters the heat exchanging panels 102, 104, 106, 108. In an exemplary application, the mass flow rate of the coolant through the cooling door assembly is substantially constant. Since coolant in a gas phase has a greater volume than the same coolant in a liquid phase, the return lines in the cooling door assembly 110 are configured with a greater diameter than the supply lines within the cooling door assembly 110. Accordingly, the frame supply interconnects 180 and 182 have a smaller diameter than the frame return interconnects 184 and 186. The frame supply lines 124, 126, and 190, the cooling door supply line 140, and the panel supply lines 142, 144, 146, and 148 have a smaller diameter than the frame return line 188, the cooling door return line 158, and the panel return lines 150, 152, 154, and 156. The components of the flex assembly 138 have smaller diameters than the components of the flex assembly 136. The interconnects of the swivel joint 128 and the mounting block 116 are smaller in diameter than the interconnects of the swivel joint 130 and the mounting block 118, respectively. Similarly, the external supply line interconnects (not shown) and the external supply lines (not shown) have a smaller diameter than the external return line interconnects (not shown) and the external return lines(not shown), respectively. Configuring the components in the supply path with smaller diameters than the complimentary components in the return path functions to alleviate increased pressure due to the phase change of the coolant from liquid to gas.
In some embodiments, a single swivel joint and a single mounting block are used, where the swivel joint and the mounting block coupled to the swivel joint are each configured with at least two independent fluid paths. One fluid path is used to supply coolant to the cooling door from the frame, and another fluid path is used to return coolant from the cooling door to the frame. In such a configuration, a flux assembly and a cooling door supply line are used to couple the single swivel joint to each of the panel supply lines.
The heat exchanging panels 208, 206, 204, 202 are also coupled to panel return lines 250, 252, 254, 246, respectively, to output fluid from the heat exchanging panels. The panel return lines 250, 252, 254, 256 are coupled to a cooling door return line 258, which is coupled to a flex assembly 236. The flex assembly 236 is coupled to the return fluid path of the swivel joint 230.
The mounting block 218 also includes two independent fluid paths, a supply fluid path and a return fluid path. The supply fluid path of the mounting block 218 is coupled to the supply fluid path of the swivel joint 230 and to one or more frame supply lines (not shown). The frame supply line(s) is coupled to frame supply interconnects 280, 282. The return fluid path of the mounting block 218 is coupled to the return fluid path of the swivel joint 230 and to a frame return line (not shown). The frame return line(s) is coupled to frame return interconnects 284, 286.
The cooling door 214 is mounted to the frame 212 using a plurality of hinges, such as hinges 232 and 234. In some embodiments, the swivel joint 230 is also configured as a load-bearing hinge.
The single swivel joint configuration of the cooling door assembly 210 reduces the number of swivel joints and mounting block, and also reduces the amount of frame fluid lines used to direct fluid flow to and from the cooling door 214. The cooling door assembly 210 can be configured as either a single-phase cooling system or a two-phase cooling system.
The cooling door assemblies described and illustrated in relation to
In another exemplary configuration, a single input swivel joint is coupled to a common cooling door supply line and a pair of output swivel joints. Each output swivel joint is coupled to multiple heat exchanging panels.
The outlet swivel joint 330 is coupled to an outlet mounting block 318, and the outlet swivel joint 331 is coupled to an outlet mounting block 319. The mounting block 318 is 25 fluidically coupled to the frame 312 via frame return line 323, and the mounting block 319 is fluidically coupled to the frame 312 via a frame return line 329. Each of the mounting blocks 318, 319 are mechanically coupled to the front frame plate 303 via a plurality of grommets 315 and 321, respectively.
Each of the swivel joints 328, 330, 331 is configured with a fluid path, which is coupled to a fluid path within the mounting blocks 316, 318, 319, respectively. The fluid path through the mounting block 316 and the inlet swivel joint 328 provides a supply fluid path to supply fluid from the frame 312 to the cooling door 314. A common cooling door supply line 338 (
The frame return line 329 is coupled to the frame return line 323 via a flexible piping 325. The flexibility of the flexible piping provides independent movement of the mounting block 318/swivel joint 330 relative to the mounting block 319/swivel joint 331. If the mounting block 318/swivel joint 330 were rigidly coupled to the mounting block 319/swivel joint 331, then movement of one would cause in movement of the other. However, movement of both the mounting block 318/swivel joint 330 and the mounting block 319/swivel joint 331 may not be needed for proper alignment. The flexible piping 325 provides this independent movement.
Fluid is output from the frame 312 via frame return interconnects 384, 386, which are coupled to external return lines (not shown). The frame return interconnects 384, 386 are coupled to the frame return line 323. Fluid is input to the frame 312 via frame supply interconnects 380, 382, which are coupled to external supply lines (not shown). The frame supply interconnects 380, 382 are coupled to the mounting block 316 via frame supply lines 324 and 326. In some embodiments, flexible piping is included in either the frame supply line 324 and/or the frame supply line 326, such as flexible piping 327. Use of flexible piping in the frame supply lines provides float for properly aligning the mounting block 316/swivel joint 328.
The movement provided by the grommets and flexible piping enables the swivel joints to float into proper alignment of the cooling door relative to the frame. When mounting the cooling door to the frame, the hinge axis and the swivel joint axis must be aligned. The movement provided by the grommets and/or the flexible piping enable proper alignment of the cooling door to the frame.
Although not shown in
In some embodiments, the swivel joints 328, 330, 331 are configured as load-bearing elements and therefore also function as hinges. In other embodiments, hinges independent of the swivel joints are used, in which case the swivel joints may or may not be configured as load-bearing elements.
The cooling door assembly 310 can be configured as either a single-phase cooling system or a two-phase cooling system.
The cooling door assemblies are described above as including a cooling door coupled to a frame, and the frame is mounted to an electronics enclosure. In this configuration, the cooling door assemblies are mounted to the electronics enclosure without having to add additional plumbing to the electronics enclosure. Alternatively, the cooling doors are configured to mount directly to the electronics enclosures. In such configurations, additional plumbing, such as frame supply lines, frame return lines, and/or mounting blocks, is added to the electronics enclosure to provide the necessary fluid connections to the external fluid supply and return lines.
In some embodiments, the cooling door is further configured to provide an amount of electromagnetic interference (EMI) protection, such as adding a screen with opening to allow airflow the heat exchangers. Additionally, EMI gasketing can be used where the frame attaches to the rack and around where the cooling door closes. EMI gasketing functions to seal the cooling door and restrict the air from leaving the enclosure without passing through the heat exchangers in the cooling door.
The present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention. Such reference herein to specific embodiments and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiment chosen for illustration without departing from the spirit and scope of the invention.
This application claims priority of U.S. provisional application Ser. No. 61/068,891, filed Mar. 10, 2008, and entitled “Fan Tray for Supplemental Air Flow”, by these same inventors. This application incorporates U.S. provisional application Ser. No. 61/068,891 in its entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61068891 | Mar 2008 | US |
