Cooling assembly for electronics drawer using passive fluid loop and air-cooled cover

Abstract

A cooling apparatus for electronic drawers utilizing a passive fluid cooling loop in conjunction with an air cooled drawer cover. The air cooled cover provides an increased surface area from which to transfer heat to cooling air flowing through the drawer. The increased cooling surface uses available space within the drawer, which may be other than immediately adjacent to a high power device within the drawer. The passive fluid cooling loop provides heat transfer from the high power device to the air cooled cover assembly, allowing placement of the air cooled cover assembly other than immediately adjacent to the high power device. The cooling apparatus is easily disengaged from the electronics drawer, providing access to devices within the drawer.

Description

FIELD OF THE INVENTION [0001] The present invention relates in general to cooling electronics systems. In particular, the present invention relates to enhanced cooling of one or more high power electronic components within an air cooled electronics drawer. BACKGROUND OF THE INVENTION [0002] As is known, operating electronic devices produce heat. This heat should be removed from the devices in order to maintain device junction temperatures within desirable limits: failure to remove the heat thus produced results in increased device temperatures, potentially leading to thermal runaway conditions. Several trends in the electronics industry have combined to increase the importance of thermal management, including heat removal for electronic devices, including technologies where thermal management has traditionally been less of a concern, such as CMOS. In particular, the need for faster and more densely packed circuits has had a direct impact on the importance of thermal management. Firs...

AI Technical Summary

Benefits of technology

[0009] The shortcomings of the prior art are overcome, and further advantages realized, by the provision of a passive liquid cooling loop and air cooled cover assembly for an electronics drawer, per the teachings of the present invention. The air cooled cover assembly provides an increased surface area from which to transfer heat to air flowing through the drawer, by utilizing available space within a drawer. The passive liquid cooling loop provides heat transfer from a high power device to the air cooled cover assembly, allowing placement of the air cooled cover assembly other than immediately adjacent to the high power device.

[0013] It is therefore an object of the present invention to provide enhanced air cooling of high power devices within an electronics drawer, by transferring heat from the high power device to an extended surface area in thermal contact with a high thermal conductivity drawer cover.

[0015] It is a further object of the present invention to provide an electronics drawer cover with extended heat transfer surfaces and a passive fluid cooling loop in a disengagable unit, thereby facilitating access to drawer components for service, repair, replacement, etc., as well as field upgrades of existing electronics drawers.

Problems solved by technology

This heat should be removed from the devices in order to maintain device junction temperatures within desirable limits: failure to remove the heat thus produced results in increased device temperatures, potentially leading to thermal runaway conditions.

First, power dissipation, and therefore heat production, increases as the device operating frequencies increase.

Finally, as more and more devices are packed onto a single chip, power density (Watts / cm2) increases, resulting in the need to remove more power from a given size chip or module.

These trends have combined to create applications where it is no longer desirable to remove the heat from modern devices solely by traditional air cooling methods, such as by using traditional air cooled heat sinks.

While alternatives to air cooling are known, such as chilled water and refrigeration systems, these alternatives tend to increase both manufacturing and operational costs, and therefore tend to be applied primarily in high performance applications.

While an increase in any of these factors tends to improve the efficiency with which heat transfers from heatsink fins to ambient air, design considerations may place practical limitations on the extent to which any parameter may be increased, and interactions between the various parameters may limit the effectiveness of a particular parameter change.

Electronic systems are designed to operate within existing customer installations, and typically do not have the flexibility to require reduced ambient air temperatures.

Both airflow rates and pressure drops are frequently limited by other design considerations, such as acoustic constraints.

The drawer volume constraints therefore place a design limitation on the maximum size heatsink that can be directly attached to a high power device.

This places a practical limitation on the extent to which high power devices such as processor 132 may be air cooled within a limited volume drawer.

The available volume may not be conveniently located adjacent to a high power device, however, such as processor 132, and therefore may not provide a volume into which a traditional heat sink directly attached to a high power device may be extended.

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