FEATURE
Vertiv
Vertiv EFC 450 indirect free cooling units
are used exclusively on NGD’s 250,000
sqft top floor for indirect free cooling,
evaporative cooling and DX backup. There
are 67 units providing 28.5mw of cooling
on an N+1 basis. These indirect free cooling
units allow NGD to control the ingress
of contaminants and humidity, ensuring
sealed white space environments.
SUITABLE
COLOCATION
PROVIDERS IN THE
UK – AND MANY
PARTS OF EUROPE
– ARE FEW AND
FAR BETWEEN.
Abundant power and significant ongoing
investment in state-of-the-art cooling and
energy management technology ensures
Next Generation Data’s (NGD) hyperscale
data centre in South Wales continues
to meet and future-proof highly varied
customer requirements. From delivering
standard 4kW rack solutions up to 60kW
per rack and beyond – with resilience at a
minimum of N+20%.
The 750,000 sqft colocation and cloud
hosting facility was the first to receive
a UK Government Climate Change
Agreement (CCA) certification in 2104,
making it exempt from carbon taxes. It
was also the first in Europe to source
100% of its power from renewables, an
initiative taken from Day One over 10
years ago. Further, the considerable 180
MW direct from Supergrid power supply
remains unique in Europe.
Stulz
On NGD’s 250,000 sqft ground floor,
comprising 31 separate data halls drawing
46
Issue 14
a total of 32 MW, a Stulz GE system is
installed. The indoor unit has two cooling
components, a direct expansion (DX)
cooling coil and a free cooling coil.
It utilises outdoor air for free-cooling in
cooler months when the outside ambient
air temperature is below 20°C, with
indirect transfer via glycol water solution
maintaining the vapour seal integrity of
the data centre.
The system automatically switches to
free-cooling mode, where dry cooler fans
are allowed to run and cool the water
to approximately 5°C above ambient
temperature before it is pumped through
the free cooling coil. In these cooler
months dependant on water temperature
and/or heatload demands, the water can
be used in ‘Mixed Mode’.
In this mode the water is directed
through both proportionally controlled
valves and enables proportional free
cooling and water-cooled DX cooling to
work together. Crucially, 25% Ethylene
Glycol is added to water purely as an
anti-freeze to prevent the dry cooler
from freezing when the outdoor ambient
temperature is below zero.
In warmer months when the external
ambient temperature is above 20°C, the
system operates as a water-cooled DX
system and the refrigeration compressor
rejects heat into the water via a plate
heat exchange (PHX) condenser. The
water is pumped to the Transtherm air
blast cooler where it is cooled and the
heat rejected to air.
The system works in three modes.
During winter operation mode return
air from the data centre is cooled down,
leveraging the heat exchange process
with external cold air. There is no need
to run the evaporative system and the
fan speed is controlled by the external
air temperature.
In summer, the evaporative system
must run in order to saturate the air.
This enables the unit to cool the data
centre air even with high external air
temperatures. By saturating the air, the
dry bulb temperature can be reduced. In
the case of extreme external conditions, a
Direct Expansion (DX) system is available
to provide additional cooling.
DX systems are sized to provide partial
backup for the overall cooling load and are
designed to provide maximum efficiency
with minimum energy consumption.
Custom HPC cooling
Where required, for specialist HPC and
other high-density environments, NGD
provides dedicated cooling solutions,
such as the one designed for a major
international insurance firm. The company
required a 40kW rack configuration
including direct liquid cooling to ensure
optimised PUE.
Working closely with the customer,
NGD’s engineering team designed, built
and installed the HPC rack environment,
including a bespoke direct liquid cooling
system, in less than three weeks. The
liquid cooling allows highly efficient heat
removal and avoids onboard hot spots,
therefore removing the problems of high
temperatures without using excessive air
circulation which is both expensive and
very noisy. ◊
www.intelligentdatacentres.com