Content supplied
by the DCA
The data centre sector
is rising to the challenge
of identifying innovative
power and cooling
solutions and one such
option could be liquid
based. Jon Summers,
Scientific Leader, RISE
North, Luleå, SWEDEN,
tells us why data centre
operators need to consider
how to integrate liquid
distribution into their
facilities to futureproof
their operations.
ne of the main hardware
components of the digital
age is the digital processing
unit (DPU). Whether central,
graphical or otherwise, it consumes
a major portion of the energy in the
operation of data centres. The ratio of
the surface areas of a DPU to the area of
a data hall (usually a room within a data
centre) in which DPUs are housed, can be
as high as 1 to 20 million.
O
The data centre draws electrical current
from the electrical power grid and more
than 50% of this current terminates at
a distributed array of DPUs, where up to
200 amperes are pumped into an area of
approximately 200 square millimetres.
It is not difficult therefore to realise that the
operational voltage of the DPU combined
with the incoming current consumes
power, but there are no moving parts
inside the DPU to consume this energy at
any time rate and so all of this electrical
power in a 200 square millimetre area is
converted to thermal power.
Thermal management of data centres
has therefore evolved to become a broad
engineering discipline that involves
equipment for thermal connections and
transfers to carry the thermal power away
from the DPUs so that they can continue to
perform their tasks without overheating.
The transferred thermal power from
the DPUs is rejected to the outside
environment. Traditional thermal
connections used today are heat sinks and
heat exchangers with thermal transport
being achieved by forced convection of air,
however there are limits to this approach
of moving the heat from the DPUs due to
the low thermal capacity of air and upper
limits of practical airflow rates.
Historically, DPU heat fluxes have been
increasing and are expected to continue
to rise, with values greater than 1 MW per
square metre for some applications.
Jon Summers, Scientific Leader, RISE
North, Luleå, SWEDEN
With these values of heat fluxes, it is not
practical to remove the heat totally with
air, so there is a growing spectrum of
heat removal technologies that employ
liquids. One can argue that data centres
have already been making use of liquids
to remove heat from the data halls with
computer room air handling/conditioning
(CRAH/CRAC) units, where chilled water or a
refrigerant are used respectively to transport
thermal energy out of the data hall.
However, the term liquid cooling is
referring to the use of liquids that come
near the information technology racks.
Therefore, this requires the data centre
to distribute liquids into the data hall,
perhaps in the same fashion as electrical
Liquid cooling on
the rise
62
Issue 07
www.intelligentdatacentres.com