Case Studies

at the ends of the cold aisles to seal them off and
used under-floor fans to force cold air into the
enclosed space,” he says.
Although it performed adequately, Musgrove found
that this approach had drawbacks. “It placed too much
strain on the floor-mount precision cooling units,
which weren’t designed to handle the intense, localized
heat loads of high-density blade servers,” he says. “The
inefficiency of relying strictly on floor-mount cooling to
cool hot zones added significantly to the electrical
power draw and costs of operating the data center in
Houston’s blazing heat and high humidity.
“And, the temperature wasn’t completely uniform—it
comes in at about 54 degrees at the floor, but rises to
about 70 by the time it reaches the ceiling.” Naturally,
this posed significant threats to the operation and
li
fespan of blade servers at the top of the racks.
When the time came to add a second, 1,000-server
cluster in 2006, Musgrove called on local Liebert
R
e
p
r
esentatives from Emerson Network Power to
recommend a dynamic and scalable high-density
infrastructure that would meet HESS’
computing demands.
The Solution
After conducting air-flow modeling tests on the entire
d
a
t
a c
enter, Liebert representatives from Bud Griffin
& Associates recommended supplementing existing
un
de
r-floor cooling with the Liebert XD family of
extreme density cooling solutions, which would
bring a high-density cooling solution closer to the
so
urc
e o
f the he
a
t.
The Liebert XD family provides a flexible, scalable and
w
a
terless solution that delivers sensible cooling of
mor
e than 500 Watts per square foot. Liebert XD
m
odules use an environmentally friendly, pumped
refrigerant to achieve high efficiencies. The refrigerant
is pumped as a liquid, converts to a gas within the
heat exchangers and then is returned to the
pumping station where it is re-condensed to liquid.
A combination of Liebert XD supplemental cooling
with room-level cooling can reduce cooling-related
energy costs by 25 to 30 percent compared to
r
oom c
oolin
g alone. For example, a 45-ton
traditional floor-mount precision cooling system
r
equires 15 to 18 hp to operate its evaporator fan
motors. By contrast, each Liebert XD unit uses a
1⁄ 2-hp fan, for a savings of 10 to 13 hp and a
c
or
r
e
s
ponding decrease in the heat load
generated by that working horsepower.
A
Customer Success
f
rom the Experts in
Business-Critical Continuity™
“The system has done exactly what we expected
it to do. It keeps the equipment at a safe
temperature, which keeps it running, and
that keeps our geosciences group happy.”
Michael Musgrove, supervisor of Computer Operations,
HESS’s Exploration & Production Division