Research Papers

Design and Control of the IBM Power 775 Supercomputer Water Conditioning Unit

[+] Author and Article Information
Michael J. Ellsworth, Jr., Frank Cascio, Eileen Behrendt

High End Power Systems Development,
IBM Corporation,
Poughkeepsie, NY 12601

Randy J. Zoodsma

Thermal Engineering and Technologies,
IBM Corporation,
Poughkeepsie, NY 12601

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received October 30, 2013; final manuscript received July 25, 2014; published online September 19, 2014. Assoc. Editor: Ashish Gupta.

J. Electron. Packag 136(4), 041009 (Sep 19, 2014) (9 pages) Paper No: EP-13-1124; doi: 10.1115/1.4028119 History: Received October 30, 2013; Revised July 25, 2014

In 2011, IBM announced the Power 775 supercomputing node/system which, for the time, was a significant increase in computing performance and energy efficiency. The system was designed from the start with water cooling in mind. The result: a system with greater than 95% of its heat load conducted directly to water and a system that, together with a rear door heat exchanger (HX), removes 100% of its heat load to water with no requirement for room air conditioning. In addition to direct water cooling the processor, the memory, power conversion, and input–output electronics also conduct their heat directly to water. Also included within the framework of the system is a disk storage unit (i.e., disk enclosure) containing an interboard air-to-water HX. The heart of the water cooling system is the water conditioning unit (WCU). The WCU circulates system water at a controlled temperature and flow rate while also transferring the electronics heat load to the data center facility building chilled water (BCW) system. The brain for this system is the motor drive and control assembly (MDA-WCU). In addition to the pump motor drive function, the MDA-WCU contains the control circuitry and associated firmware that maintains system water at a prescribed temperature above the room dew point irrespective of system and or facilities thermal/flow transients. It is also capable of error detection and fault isolation that, together with higher level system firmware, facilitates serviceability, and availability. The paper will present the WCU and MDA-WCU design with an emphasis on the control methodologies and algorithms.

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Fig. 1

Schematic of the power 775 water cooling system

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Fig. 3

WCU—exploded view

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Fig. 4

Centrifugal pump (isometric)

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Fig. 5

Centrifugal pump (cross-sectional view)

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Fig. 6

Pump pressure/flow/power characteristic curves at a rotational speed of 366.5 rad/s (3500 rpm)

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Fig. 7

WCU equivalent flow circuit

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Fig. 9

Reservoir tank (transparent cylindrical section for visualization only)

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Fig. 10

Control valve flow characteristic

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Fig. 12

Set point based on room dew point (Ta)

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Fig. 13

Set point based on facilities BCW inlet and rack power (Tb)

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Fig. 14

Reservoir float sensors

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Fig. 15

Pump rotational speed as a function of regulation set point




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