Adaptive cooling method for computer rack enclosure

• US 20070097636A1
• Filed: 08/04/2006
• Published: 05/03/2007
• Est. Priority Date: 08/05/2005
• Status: Active Grant

• Current Assignee: Wilimington Research and Development Corp.
• Original Assignee: Wilimington Research and Development Corp.
• Inventors: Boyd, Stephen, Johnson, Douglas
• Granted Patent: US 8,348,731 B2
• Time in Patent Office: Days
• US Class Current: 361/695
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: H05K 7/20145 Means for directing air flow, e.g. ducts, deflectors, plenum or guides
• CPC Class Codes: H05K 7/20209 Thermal management, e.g. fan control
• CPC Class Codes: H05K 7/20572 within cabinets for removing heat from sub-racks, e.g. plenum
• CPC Class Codes: H05K 7/207 Thermal management, e.g. cabinet temperature control
• CPC Class Codes: H05K 7/20745 within rooms for removing heat from cabinets, e.g. by air conditioning device
• CPC Class Codes: H05K 7/20836 Thermal management, e.g. server temperature control

Abstract

A technique for cooling equipment racks that contain multiple individual devices, such as computers, that each have their own internal cooling fans. An air passage (“shunt tube”) is placed between a compartment inside the rack, and the ambient air outside the rack, or between compartments inside the rack. Sensors inside the air passage detect movement of the air inside the passage, and thus indirectly measure the presence of a differential pressure. The preferred sensor embodiment uses temperature sensors, and takes advantage of the differences of the air temperatures inside the computer rack, and outside the computer rack (or between internal computer rack compartments) to determine if the air is moving through the air passage, and which direction the air is moving. In response to the measurements, a control system is configured to drive the plenum to a slight vacuum, and then slowly reduce an exhaust fan until the plenum is slightly pressurized, at which point the fan speeds up and again creates a slight vacuum. This allows the rack enclosure to continuously adapt to any changes in cooling requirements, as the computer utilization changes.

Claims

1. A rack enclosure for enclosing one or more computer systems, the rack enclosure comprising:

at least one internal plenum providing an enclosed space for airflow;

a shunt tube, disposed between an internal plenum and ambient outside the enclosure, or disposed between two internal plenums;

at least one temperature sensor, disposed within the shunt tube, for determining a measured shunt air temperature inside the shunt tube;

a pressure determining circuit, for determining a pressure from a difference in the measured shunt temperature and at least one of a measured or assumed ambient or plenum temperatures; and

a modulating airflow device, for controlling airflow into or out of the enclosure in response to the determined pressure.

2. An apparatus as in claim 1, wherein the shunt tube is disposed between an internal plenum and ambient outside the enclosure.

3. An apparatus as in claim 2 comprising:

a plenum temperature sensor additionally, disposed in an end of the shunt tube that extends into one of the plenums.

4. An apparatus as in claim 2 additionally comprising:

a ambient temperature sensor disposed in an end of the shunt tube that extends into the ambient outside the enclosure.

5. An apparatus as in claim 1 wherein the shunt tube is disposed between two internal plenums within the enclosure.

7. An apparatus as in claim 1, wherein the temperature sensor provides a temperature gradient;

and the temperature gradient is used to determine the pressure.

6. An apparatus as in claim 6 wherein the two plenums are an intake plenum and an exhaust plenum that respectively isolate intake and exhaust fans internal to the computer systems.

8. A method for controlling an airflow modulating device arranged for supplying or exhausting cooling air for a rack enclosure containing multiple computers, the method comprising the steps of:

disposing a shunt tube between a plenum area inside the rack enclosure and an area outside the plenum area;

measuring a temperature differential across said shunt tube;

determining a direction of airflow though said air shunt tube from said temperature differential, and

controlling the airflow modulating device in response to said direction determining step, to meet a cooling air demand.

9. A method as in claim 8, the step of determining the direction of airflow further comprising:

disposing a first temperature sensor within a central portion of the shunt tube; and

disposing a second temperature sensor at one end of the shunt tube.

10. A method as in claim 8 wherein the rack enclosure further comprises an intake plenum and exhaust plenum, and the shunt tube is disposed between the intake and exhaust plenums.