cooling
Intelligent choices
Since its opening in 2009 Stulz UK has supplied the cooling systems
at NGD’s mega data centre in South Wales, a Tier 3 facility offering
both private and shared colocation data halls across 750,000ft2.
With up to 180MW power available from a direct SuperGrid
connection, the facility has proved increasingly popular with
enterprise and service provider organisations operating high density
environments such as those found in HPC and cloud.
Two years ago, in response to increasing requirements from
customers to further reduce PUE, NGD evaluated alternative
solutions to the DX direct expansion systems originally supplied
by Stulz. This included an adiabatic system (IAC) and though
demonstrating very energy efficient PUE figures it was rejected
due to the major infrastructure works involved, large footprint/low
cooling capacity, high water usage and treatment requirement, as
well as on grounds of cost.
Stulz UK subsequently replaced the DX systems with its latest
cooling solution which intelligently determines the optimal mode
of operation according to the dictates of the external ambient
conditions and data hall requirements. This solution enables the
system to operate in free cooling mode for the majority of the year,
to compensate for these hotspots is
costly.
For cooling higher density racks,
HACS incorporating doors, ceilings,
in-row cooling systems and variable
speed temperature controlled fans
may provide a more efficient solution
whilst ensuring server availability. This
only providing supplementary cooling in times of elevated external
ambient conditions.
The scalable system design is based on the glycol free cooling
GE system and features a unique pipework arrangement: a low
loss header within the dry cooler compound and individual flexible
pipes for distributing to each individual CRAC unit. The pipes are
double insulated and have both an inner and outer pipe. In the
event that the inner pipe leaks it transfers into the outer pipe which
has its own leak detection installed. The pipes can be made in any
lengths therefore minimising joints and can be installed in a fraction
of the time it would take for a traditional piping system.
The first GE system was installed and commissioned within five
weeks and the annualised PUE figure achieved was 1.18. The
cost of the system compared to the IAC was almost 60 per cent
lower and the ROI for the GE system was three years compared to
six years for the IAC.
Thanks to this intelligent cooling solution NGD has been able
to move in line with customer requirements, delivering solutions
from a standard 4kW rack up to 60kW per rack and beyond with
resilience at a minimum of N+20 per cent.
is because HACS is a self-contained
‘room within a room’ system that
removes server exhaust air from the
data hall at large and precisely targets
cold air to specific racks or rows.
By maintaining higher return
temperatures HACS will also ensure
cooling unit capacities are maximised
whilst the power consumed (including
by fans) is reduced. Apart from saving
energy this will optimise the potential for
free cooling days. HACS can also be
deployed without impacting the existing
cooling architecture – unlike CACS –
as it does not affect the temperature
of the entire computer room.
25