ASHRAE Journal - July 2019 - 4

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EDITORIAL
Editor
Jay Scott
jayscott@ashrae.org
Senior Managing Editor
Sarah Foster
sfoster@ashrae.org
Associate Editor
Rebecca Matyasovski
rmatyasovski@ashrae.org
Associate Editor
Jeri Alger
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Associate Editor
Tani Palefski
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Associate Editor
Mary Kate McGowan
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Associate Editor
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Contributing Editor, Europe & Middle East
W. Stephen Comstock
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ASHRAE OFFICERS
President
Sheila J. Hayter, P.E.
President-Elect
Darryl K. Boyce, P.Eng.
Treasurer
Charles E. Gulledge III, P.E.
Vice Presidents
Julia A. Keen, Ph.D., P.E.
Malcolm Dennis Knight, P.E.
Farooq Mehboob, P.E.
Michael Schwedler, P.E.
Secretary & Executive Vice President
Jeff H. Littleton
POLICY GROUP
2018 - 19 Chair
Publications Committee
José Correa, P.E.
Washington Ofﬁce
washdc@ashrae.org

ASHRAE JOURNAL

Jay Scott

Liquid-Cooled Data Centers on the Rise
Adoption of liquid-cooled IT equipment in the world's data centers is
clearly on the rise.
A technical feature (Page 20) and the
Data Centers column (Page 56) this
month focus on liquid-cooling trends
in data centers.
With each new generation of IT
equipment, manufacturers are moving
to increase their processing capabilities to support such things as artiﬁcial
intelligence and high performance
computing.
THE HEAT GENERATED by these
more powerful processors is pushing
against the limits of conventional aircooled approaches.
"Air cooling has worked well for systems that deploy processors up to 150
W," the authors write in the technical feature, "but IT equipment is now
being manufactured with processors
well above 150 W where air cooling is
no longer practical."
Also, other components supporting
those processors, such as memory and
voltage regulators, are pushing toward
liquid cooling.
ASHRAE TC 9.9, Mission Critical
Facilities, Data Centers, Technology
Spaces and Electronic Equipment,
recently published a white paper
"Water-Cooled Servers-Common
Designs, Components and Processes,"
available for free at https://tinyurl.
com/y239t4rv. TC 9.9 developed the
ASHRAE Datacom Series book Liquid
Cooling Guidelines for Datacom Equipment
Centers.

TC 9.9 decided to outline some of
the common processes, parts and
materials to provide focus for use
in water-cooled designs and the
increased use of water-cooled servers
in data centers.
While most of the general rules for
air-cooled implementations apply,
the authors write operators should
have cooling contingency plans,
cooling system redundancies, critical subsystems such as pumps that
have high reliability, and have those
pumps or rack-based cooling systems
on uninterruptible power supply.
SPECIAL ATTENTION SHOULD be
paid to temperature control, preventing condensation, the technology
cooling system loop's water cleanliness, wetted material requirements
and water chemistry, the authors
write.
The columnists point out higher temperature liquid cooling offers the prospect of greatly reducing or even eliminating the need for using mechanical
cooling, replacing it with 100% ﬂuid
economizer systems.
Heat rejection options involve the use
of closed-circuit cooling to maintain
efﬁciency and reduce maintenance.
Open circuit cooling towers with heat
exchangers or closed-circuit cooling
towers can be used for high efﬁciency
heat rejection, while hybrid closed circuit cooling towers or adiabatic ﬂuid
coolers offer the advantage of lower
water use.
Enjoy the issue.

Mission Statement: ASHRAE Journal reviews current HVAC&R technology of broad interest through publication of application-oriented articles. ASHRAE Journal's editorial content ranges from back-to-basics features
to reviews of emerging technologies, covering the entire spectrum of professional interest from design and
construction practices to commissioning and the service life of HVAC&R environmental systems.
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ASHRAE Journal - July 2019

Table of Contents for the Digital Edition of ASHRAE Journal - July 2019