WO2017069761A1

WO2017069761A1 - Electronics cooling

Info

Publication number: WO2017069761A1
Application number: PCT/US2015/056902
Authority: WO
Inventors: Kevin B. Leigh; John Norton; Darrel G. Gaston; Matthew E. STEVENS
Original assignee: Hewlett-Packard Enterprise
Priority date: 2015-10-22
Filing date: 2015-10-22
Publication date: 2017-04-27

Abstract

An example cooling system for guiding cooling air to electronic components in an electronics rack includes a duct assembly. The duct assembly has a duct body, an inlet, and an outlet. The duct body defines an air flow path. The duct body extends along a perimeter of a main rack compartment of an electronics rack. The inlet on a first end of the duct body is fluidly open to ambient air. The outlet on a second end of the duct body mechanically couples to an electrical component.

Description

ELECTRONICS COOLING

Background

[0001] In some situations, a plurality of computer servers or other electronic systems are mounted in a rack. Air typically flows from a front of the rack to a rear of the rack. The air typically enters the front of the rack as cool ambient air and is heated as the air flows across electrical components at the front of the rack to components toward the rear of the rack and exits the rear of the rack at a higher temperature than the cool ambient air. As a result, the components at the rear of the rack are typically not cooled as much as the components at the front of the rack.

Brief Description of the Drawings

[0002] Figure 1 is a side view schematically illustrating an electronics rack including a cooling system according to an example of the present disclosure.

[0003] Figure 2 is a side view schematically illustrating airflow through an electronics rack including a cooling system according to the example of Figure 1 of the present disclosure.

[0004] Figure 3 is a side perspective view illustrating an electronics rack including a cooling system according to an example of the present disclosure.

[0005] Figure 4 is a bottom perspective view illustrating an electronics rack including a cooling system according to the example of Figure 3 of the present disclosure.

[0006] Figures 5A and 5B are side perspective views illustrating a cooling system according to an example of the present disclosure.

[0007] Figure 6 is an exploded view of an inlet plenum a cooling system according to an example of the present disclosure.

[0008] Figure 7 is a flow chart illustrating an example method of using a cooling system in accordance with the present disclosure. Detailed Description

[0009] In the following detailed description, reference is made to the

accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise.

[0010] Electronic components, including servers, are typically mounted in close quarters within an electronics rack. Electronic components are separated by a limited amount of space, thereby reducing the dimensions within which to provide adequate cooling, which leads to inadequate cooling of certain areas within the electronics rack. Electronic components mounted in racks can lead to high thermal density.

[0011] Cooling of electronic components in racks can employ active cooling (e.g., fans) to facilitate a variety of airflow patterns, or use passive thermal radiation to dissipate heat. Typically, ambient air is drawn into a rack through a front of the rack, the air passes over electrical components inside a primary air chamber inside the rack, and the air flow then exits through a back of the rack. Due to the direction of airflow from the front to the rear of the rack, components in the rear of the rack typically receive air that has been warmed by the air first passing over and cooling the components in the front of the rack. Server rooms often group rack cabinets together so that that the racks form aisles. This can simplify cooling by supplying cool air to a front of the racks and collecting hot air from the rear of the racks.

[0012] In some cases, supplemental, or secondary, cooling may be desired. Supplemental cooling systems can be employed to decrease the air temperature within the electronics rack. A duct cooling system can be provided as a supplemental cooling system. A duct cooling system can facilitate air circulation by providing pathways for guiding the airflow to select locations or components housed in the rack, for example, components at the rear of the rack. Space within the electronics racks is largely occupied by electrical components, and a ducted system occupying space otherwise suited for electronic systems and components can be undesirable.

[0013] Figure 1 is a schematic illustrate an exemplary electronics rack 10 including a frame 12 in which systems 14 are operated. For sake of simplicity and ease of viewing, rack 10 is illustrated in Figure 1 with a single system 14 having two electronic components or devices 16. Frame 12 is typically densely packed with systems 14 that are, in turn, densely packed with devices 16.

Electronic systems 14 and devices 16 occupy a large volume of a primary or main rack compartment 18 within rack 10. Systems 14 can be rack-mount servers or blade servers, for example. Each electronic device 16 of each system 14 generates a thermal load as it is operated. Main rack compartment 18 forms a primary air chamber through which air flows to cool devices 16. A cooling system 20 is included in rack 10 to provide auxiliary cooling to select electronic components housed within rack 10, as described in greater detail below.

[0014] Cooling system 20 pulls in cool ambient air from outside rack 10 and includes a duct assembly 22 to channel or direct cool air to select components within rack 10. Duct assembly 22 of cooling system 20 includes an inlet 24, an outlet 26, and ductwork 28 extending between inlet 24 and outlet 26 to deliver cool air and remove air heated by the select component. By channeling a cooling air flow over only selected electrical components, cooling system 20 provides supplemental cooling to the cooling provided by a primary air flow through main rack compartment 18 to reduce the ambient air temperature at the selected components and help increase operating efficiencies of the selected components.

[0015] Figure 2 illustrates exemplary airflow patterns through rack 10. Various primary and secondary air flow patterns can be employed through rack 10. In general, as indicated by primary air flow path 30, cooling air is pulled into rack 10 at a front 32 of frame 12 and flows through main rack compartment 18 over devices 16 and is subsequently exhausted at a rear 34 of frame 12. Cool intake air (e.g., 40°C) is warmed as it passes over and removes a portion of the thermal load generated by devices 16 and is subsequently exhausted from rack 10 at a hotter temperature (e.g., 60°C). In addition to the generally uniformly directed cooling air passing over the components in the primary air chamber from front 32 to rear 34 of rack 10 as facilitated by primary air flow path 30, cooling system 20 directs cooling air to select components to provide additional cooling to the select components, such as power distribution unit (PDU) 36, as indicated by a secondary air flow path 40. Air drawn into front/first side 32 of rack 10 is channeled or directed through duct assembly 22 to the targeted electronic component. As indicated by air flow path 40, cooling system 20 supplies cool air to PDU 36 or other selected component in rack 10 and air heated by those components is exhausted at rear 34 of frame 12.

[0016] Cooling air supplied by cooling system 20 can be concentrated on those components that are most sensitive to temperature, that produce the greatest amounts of heat energy, and/or are near rear 34 of rack 10 and would otherwise only receive air already warmed by the passage of the air over other electronic components closer to the beginning of primary air flow path 30 or front 32 of rack 10. In some examples, the cooling capacity cooling system 20 can be targeted by secondary air flow path 40 to cooling select components in hotter areas within rack 10, including components that are temperature sensitive. The selected electronics can be vented to expel the air heated by the selected component to outside rack 10.

[0017] Cables (not shown) are typically placed in the rear area of rack 10, behind devices 16. PDU 36 is an electronic component including multiple outputs to distribute electrical power and communication to devices 16 located within rack 10. In the example illustrated in Figures 1 and 2, PDU 36 is positioned at, or proximal to, rear 34 of frame 12. Located at rear 34 of frame 12, air preheated from devices 16 closer to front 32 of main rack compartment 18 flows across PDU 36 prior to being exhausted from rack 10. The preheated air of primary air flow path 30 has a lessened capacity for cooling components at or near rear 34 of frame 12 than the cooler air pulled in at front 32 of frame 12.

[0018] Figures 3 and 4 illustrate side and bottom perspective views,

respectively, of rack 10 including cooling system 20 according to one example. Frame 12 can be any standard rack size known in the industry (e.g., 19 inch (482.6 mm), 23 inch (584.2 mm)) or non-standard size. Duct assembly 22 of cooling system 20 assembled to frame 12 does not interfere with installation or removal of equipment (e.g., systems 14, devices 16, etc.) and primary air flow cooling of main rack compartment 18. Frame 12 provides structural support for rack 10, and in some examples, panels (not shown) are attached to frame 12 to partially or fully enclose main rack compartment 18. Rack rails 44 can extend within frame 12 to provide attachment locations for systems 14. Ducted assembly 22 can be removably coupled to frame 12, rack rails 44, or otherwise coupled to rack 10. Ducted assembly 22 can generally extend along a perimeter of frame 12, interior of side panels when employed. Components of duct assembly 22 are sized and positioned such that duct assembly 32 does not interfere with or take up space within rack 10 that is otherwise suitable for servers 14 or devices 16, as described in further detail below. In other words, a density of systems 14 housed in main rack compartment 18 can be maintained in rack 10 that includes cooling system 20 as can be maintained in rack 10 without cooling system 20.

[0019] In one example, inlet 24 of duct assembly 22 is positioned along front 32 below a bottom 46 of frame 12 and outlet 26 extends along rear 34 of frame 12. Ductwork 28 extends between inlet 24 and outlet 26. Inlet 24 can be positioned below frame 12 along the intersection of front 32 and bottom 46 of frame 12. Alternatively or additionally, inlet 24 can be positioned elsewhere along front 32 of frame 12, for example, between a top 48 and bottom 46 or along either or both opposing sides 52, 54 adjacent front 32. Due to natural convection, ambient temperature of air at the bottom front of frame 12 is typically lower than toward top 48 of frame 12. Duct assembly 22 includes ductwork 28 providing an air flow pathway extending between inlet 24 and outlet 26. Inlet 24 and outlet 26 define openings at generally opposing ends of duct assembly 22. Inlet 24 and/or outlet 26 can be formed of single or multiple openings. One or more outlet 26 can be included to channel cooling air to one or more selected components. In one example, duct assembly 22 includes outlets 26 disposed along opposing sides 52, 54 adjacent PDUs 36 at rear 34. In one example, each outlet 26 has multiple openings or ports 56 to distribute cooling air across areas of the selected components (see, e.g., Figures 5A-5B).

[0020] Outlet(s) 26 can be coupled to the select electrical component to provide directed cooling air flow to the component, such as PDU 36, for example. Outlet 26 can be coupled to an air inflow side (i.e., front side) of an electronic device (e.g., PDU 36) and the heated air from cooling the electronic device (e.g., PDU 36) is released out of frame 12 at an air outflow side (i.e., rear side) of the electronic components (e.g., PDU 36) that is selectively cooled. The air inflow side of the electrical components that are selectively cooled can completely or partially open to fluidly communicate with outlet 26. Outlet 26 extends within frame 12 and is positioned directly adjacent the selected components, such as PDU 36. The selectively cooled electrical component can include inlet ports configured to be aligned with outlet ports 56 of outlet 26. Ports 56 can be evenly distributed or concentrated in specific areas along outlet 26.

[0021] With reference to Figure 4, electrical devices such as transceivers 58 can also be included in rack 10. Transceivers 58 can be positioned toward rear 34 of rack 10. In one example, transceiver 58 is an optical transceiver module is mounted in a module of PDU 36 and is powered by PDU 36. Electronic components in PDU 36 and opto-electrical components in transceiver 58 can operate at higher efficiencies and/or have a longer wear-out lifetime when the ambient temperature is lower than 70°C, for example, at 50°C. Outlet 26 can be coupled to transceiver 58 through PDU 36, or coupled separately, to cool these components and maintain lower temperatures than otherwise achieved.

[0022] Figures 5A and 5B illustrate exploded views of cooling system 20. Duct assembly 22 is pre-formed in duct sections 60a-60x, respectively. Duct assembly 22 includes a suitable number of duct sections 60a-60x to facilitate installation of duct assembly 22 into rack 10 and air flow from inlet 24 to outlet 36. Duct assembly 22 can be assembled within rack 10 prior to or after electronic components have been installed. In other words, cooling system 20 can be added an existing rack 10 already housing electronic systems 14 or during the fabrication of rack 10. Sections 60a-60x are formed and assembled into a configuration suitable to accommodate the spatial restrictions of rack 10 and access to electrical components. Sections 60a-60x of duct assembly 22 are suitable for a variety of assembled configurations. Duct assembly 22 includes multiple sections for modularity and assembly into any desired rack or other electronics enclosure. The modular nature of duct assembly 22 also allows for independent removal and replacement of sections 60a-60x after installation.

[0023] Duct assembly 22 can have a varying dimensional shape along a length of duct assembly 22, dependent on space constraints. Modular sections 60a- 60x are assembled to form a path for directing a flow of cooling air upon assembly. In one example, sections provide a cross-sectional interior area that is substantially equivalent between sections. Sections 60a-60x can have a greater width than depth. For example, duct sections 60a-60x can be

rectangular with a rectangular interior providing an air flow path. Duct sections 60a-60x can extend in a generally linear and curvilinear form. Sections 60a-60x can include corner or bent sections and straight sections. Duct sections 60a-60x can be formed and assembled to provide a path for air movement horizontally, vertically, transition from horizontal to vertical, transition from vertical to horizontal, or any other shaped form to provide airflow from inlet 24 to outlet 26. Sections 60a-60x are sized and shaped to fit in narrow areas under and through rack 10 not otherwise occupied. Sections 60a-60x can be formed of non- conductive or thermally insulative material. In one example, sections 60a-60x are formed of plastic.

[0024] Duct assembly 22 can include sections 60a-60x that are rigid, semi-rigid, or combination of rigid and semi-rigid. For example, section 60d that extends by rail 44 can be semi-rigid to provide flexibility in bending or curving around an exterior of rail 44 and can hold the desired shape after being bent. In another example, a length of section 60c transitioning from horizontal to vertical is flexible only at the bend location. In another example, sections 60a-60x are rigidly pre-formed to include bends such as vertical to horizontal and around rail 44. Semi-rigid flexibility can be achieved with accordion style segments, telescoping segments, stretchable and/or compressible segments, or other configurations. Sections 60a-60x can slide and snap-fit together. Sections 60a- 60x can include male and female ends to facilitate coupling together. Sections 60a-60x can be attached to each other in a variety of ways including fasteners such as clips, or screws, for example. Sections 60a-60x having the same or different overall cross-sectional interior area can be assembled to provide customized air delivery and to accommodate particular rack configuration.

[0025] In the example illustrated in Figures 5A-5B, sections 60a-60x are generally rectilinear and formed in a variety of shapes. In one example, sections 60a-60x generally are bent or curved in a single x, y, or z axial direction in a particular bend location. Duct assembly 22 illustrated in Figures 5A-5B include sections 60a_r60xi that mirror sections 60a₂-60x₂ as suitable to extend to two select electronic components positioned on opposing sides of rack 10. Sections 60a-60x are configured to extend to the selected component(s), wherever positioned in rack 10. In one example, a first or inlet section 60a extends linearly from inlet 24. Inlet section 60a can be formed without interior division or with interior division extending between opposing ends. With reference to Figures 3 and 4, inlet section 60a extends parallel to bottom 46 of frame 12 toward rear 34 of frame 12. Mid-sections 60bi, 60b₂ can be curvilinear to form branches for directing cool air to separate locations and components (e.g., PDUs 36) housed in separate areas of frame 12. In one example, mid-sections 60bi , 60b₂ fit below the bottom front support of rack 10 extend toward opposing sides 52, 54 of frame 12. In another section configuration, mid-sections 60ci, 60c₂ transition airflow from horizontal to vertical. Mid-sections 60ci , 60c₂ can also include a c-shaped bend (upper) to transition back to horizontal airflow. The c-shaped bend (upper) maintains a width suitable to extend along either side 52, 54 of frame 12. Mid-sections 60di, 60d₂ have u-shaped bends to fit around and exterior to rail 44 and within the space between an optional sidewall panel and rail 44. Additional and alternative mid-sections can be included. Outlet section 60x extends to and forms outlet 26. Outlet sections 60xi, 60x2 are vertical sections and can extend along an entire or partial height of rack 10. In one example, the length of outlet sections 60xi, 60x₂ is equivalent to the length of the electrical component outlet sections 60xi, 60x2 is coupled to for cooling. Sections 60a-60x described above are merely exemplary.

[0026] Figure 6 illustrates an exploded view of inlet 24 and sections 60a-60b of cooling system 20 according to one example. A faceplate 70 can be included at inlet 24. Faceplate 70 can include gratings, mesh, vertical slats, horizontal slats, or any other type or pattern that allows air flow and assists in keeping debris from entering inlet 24. As illustrated in exemplary inlet section 60a, at least one fan 72 can be positioned inside inlet 24 to pull air through inlet 24. Fans 72 can be included within duct assembly 22 to pull (or push) air from inlet 24 to outlet 26. Fans 72 can aide the airflow into, thru, and out of cooling system 20 and rack 10. Fans 72 can be included within inlet 24, outlet 26, and/or one or more duct sections 60 between inlet 24 and outlet 26 to achieve desired air flow and movement. Additionally, or alternatively, fans can be included in the component being cooled by cooling system 20. In addition, temperature and flow sensors, indicated by dashed 74, can be positioned throughout duct assembly 22 (interior or exterior) to monitor the air in and around duct assembly 22.

[0027] In one example, a management board 76 is electrically and

communicatively coupled to interface with fans 72 and sensors 74 (when employed) through cables 78. Management board 76 is generally illustrated in Figure 4. With continued reference to Figure 6, cables 78 have connectors 80 at opposing ends for coupling with other connectors 80 of cables 78,

management board 76, fans 72, or sensors 74. Cables 78, fans 72, and sensors 74 can be independently assembled into sections 60a-60x for ease of assembly of cooling system 20. Cables 78 can be suitable to extend within each respective section 60a-60x and allow coupling. In one example, cables 78 can be freely inserted into each respective section 60a-60x before assembly of sections 60a-60x forming duct assembly 22. In one example, cables 78 are routed within duct assembly 22. In one example, cables 78 are pre-assembled within each respective section 60a-60x and can be attached to an interior of the respective section 60a-60x. Alternatively, cables 78 can be attached to an exterior surface of duct assembly 22. In one example, redundant management boards 76 and/or redundant management cables 78 communicatively coupling fans 72 and sensors 74 to management board(s) 76 are included. Management boards 76 are communicatively coupled to a management controller (not shown) in rack 10. Management boards 76 can include a central processing unit (CPU) or printed circuit board (PCB) assembly positioned inside or adjacent to PDU 36. The management controllers can be supplied with information about the amount of cooling desired for each selectively cooled component as well as other data and information for achieving the desired level of cooling.

[0028] Figure 7 illustrates an example method 100 of using cooling system 20 to cooling electronic equipment housed in a rack. At 102, ambient air is received into an inlet of a cooling system in a rack. At 104, the ambient air is channeled through a duct of the cooling system to an outlet of the cooling system. At 106, the ambient air is exhausted from the outlet onto an electronic component coupled to the outlet. The outlet and electronic component are housed in the rack. At 108, the electronic component is cooled with the ambient air exhausted from the outlet. The air is heated in cooling the electronic

component. The heated air is exhausted from the electronic component and rack. The air is actively moved through the duct with fans installed in the cooling system. The air moving through the cooling system is sensed and the air flow through the cooling system is controlled.

[0029] Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

1 . A cooling system for guiding cooling air to electronic components in an electronics rack, the cooling system comprising:

a duct assembly including:

a duct body defining an air flow path, the duct body to extend along a perimeter of a main rack compartment of an electronics rack; an inlet on a first end of the duct body, the inlet fluidly open to ambient air; and

an outlet on a second end of the duct body, the outlet to mechanically couple to an electrical component.

2. The cooling system of claim 1 , comprising:

at least one fan positioned in at least one of the inlet and the outlet to move air from the inlet to the outlet.

3. The cooling system of claim 2, comprising:

a control cable extending within the duct body, the control cable connected to the at least one fan; and

a management board communicatively coupled to the at least one fan through the control cable.

4. The cooling system of claim 3, comprising:

a sensor to sense at least one of air temperature and air flow, wherein the sensor is communicatively coupled to the management board.

5. The cooling system of claim 1 , wherein the duct body is comprised of sections, and wherein the sections slidably mate with one another.

6. The cooling system of claim 1 , wherein the duct is formed of thermally non-conductive material.

7. An electronics rack comprising:

a frame including:

a first side;

a second side opposite the first side; and

a primary chamber defined between the first side and the second side;

electronic devices positioned within the primary chamber; and a cooling system including a duct assembly including:

an inlet positioned at the first side;

an outlet coupled to at least one of the electronic devices; and a duct body extending between the inlet and the outlet.

8. The electronics rack of claim 7, comprising:

at least one fan within the duct assembly.

9. The electronics rack of claim 7, wherein the duct body extends along a perimeter of the frame.

10. The electronics rack of claim 7, wherein the cooling system includes a management board to control a capacity of cooling.

1 1 . The electronics rack of claim 7, wherein the duct body extends vertically and horizontally from the first side to the second side of the frame.

12. The electronics rack of claim 7, wherein the outlet is mechanically coupled to a power distribution unit.

13. A method of cooling electronic equipment housed in a rack, the method comprising:

receiving air from ambient air into an inlet of a cooling system in a rack; channeling the air through a duct of the cooling system to an outlet of the cooling system;

exhausting the air from the outlet onto an electronic component coupled to the outlet, the outlet and electronic component housed in the rack; and

cooling the electronic component with the air exhausted from the outlet.

14. The method of claim 13, comprising:

actively moving the air through the duct with fans installed in the cooling system.

15. The method of claim 13, comprising:

sensing air moving through the cooling system; and

controlling air flow through the cooling system.