(∆T) across the heat exchanger plate
- meaning that the internal air is
always around 3C warmer than the
outside air. This significantly increases
the number of ‘hot’ days on which
evaporative cooling is operational or
refrigeration support is needed. In most
cases where indirect air-cooling is used,
a complete parallel DX or chilled water
cooling system also has to be deployed.
This seriously adds to the already
high capital costs and size of these
indirect units. There’s also an issue with
auxiliary refrigeration cooling in that it
needs large amounts of power when it
operates.
A further spoiling factor in terms of
the amount of ‘free cooling’ available
with indirect air systems is that it is
not possible for the Fresh Air inlet
and the hot air exhaust to be very far
apart. The result is that eddy currents
draw the hotter exhaust air back into
the inlet. This means that the inlet
temperature is considerably higher
than ambient air. On Free Fresh Air
we generally design the system so that
inlet and exhaust are on opposite sides
of the data centre building with no
opportunity for hot air recirculation.
Chilled Water
For the cooling of data centres
consuming 1MW and above there are
now some very efficient chilled-water
systems on the market. By combing
refrigeration-based chillers with
either dry or adiabatic/evaporative
pre-coolers, these systems harness the
‘free cooling’ power of ambient air to
significantly reduce the amount of time
that the power-hungry compressors
need to run.
Horses For Courses
There is no simple standard solution
for cooling. Every application is
absolutely unique. Chilled water can
be a great solution for megawatt and
multi-megawatt data centres often only
needing 75 kW of energy per MW
of cooling load. Indirect air cooling
is a good solution in appropriate
circumstances. DX (direct exchange)
refrigeration cooling still has its place as
a simple and quick to deploy solution.
Free Fresh Air is the most efficient,
needing only 1.5kW of energy or less
per 35kW of IT load. It is suitable for
small server rooms right through to
multi-megawatt data centres and can
bring PUEs of down to 1.05.
SAVE 90% ON YOUR DATA CENTER COOLING COSTS
The Fresh Air Cooling and Ventilation Specialists
Industrial, Commercial , IT and Data Center Evaporative Cooling
Over 350 UK Installations
No refrigerants and low carbon
ASHRAE compliant conditions
New build and retro fit
Internal and external product ranges
Advanced control system
ROI in under 1 year
New products
www.ecocooling.org | [email protected] | 01284 810586
www.netcommseurope.com
NETCOMMS europe Volume V Issue 4 2015 17