CONNECTIONS_65-e

Cooling with rear door heat exchangers
Chilled water
Graphic: R&M
CDU
(cooling disribution unit)
RDHE
(rear door heat exchanger)
050.7382
More efficiency to be expected
Further advances in microelectronics are
to be expected, with energy efficiency
increasing all the time. Innovations such as
co-packaged optics (CPO) aim to minimize
electrical transmission between chips and
fibers and reduce transmission losses. At the
same time, they can increase the number of
transmission channels. There is no need for
conventional connectors. This means that the
front panels of the devices can be designed
more openly in spite of a higher power density
in order to allow more ventilation.
Pros and cons
There are several factors to consider when
choosing a type of cooling, including the
density of the power to dissipate (power/
rack), computer workloads and packing
density, reconfiguration and patching needs,
infrastructures for heat dissipation.
Conclusion: Greater performance and higher
density in the racks do not necessarily mean
that investments and the effort involved in
heat dissipation increase proportionally. But
the demand for heat dissipation tends to
increase. Liquid-based cooling systems are
therefore worth considering in view of their
improved efficiency.
050.7384
In direct chip cooling, small channels take the
coolant into the active electronic equipment.
side heat exchangers, direct chip cooling and
immersion cooling.
– In the case of heat exchangers on the rear
of the racks (rear door heat exchangers), fans
blow the warm air through a grid of pipes
containing coolant. The liquid absorbs the
heat, is pumped to an external cooling mechanism
and returned to the heat exchanger.
– In direct chip cooling, small channels take
the coolant into the active electronic
equipment. The channels and heat sinks are
arranged above or below the heat-generating
chips. This approach requires additional
air circulation to dissipate the residual heat.
– In immersion cooling, individual servers or
entire systems are immersed in a dielectric
coolant. The liquid circulates and transports
heat away. This is the most efficient form of
cooling.
Of course, every approach has advantages
and disadvantages. As yet, there is no onesize-fits-all
solution.
The total cost of ownership (TCO) of liquid-cooled
systems is likely to be significantly
lower. However, the initial investment is
likely to be higher. The layout and premises
of the data center must be evaluated. Heat
exchangers on the racks are easy to install.
Chip cooling and immersion cooling require
specially configured equipment.
Conventional air cooling is sufficient if the
total power to dissipate is below 20 kW per
rack. If it exceeds this threshold value, R&M
believes that a strategy for liquid cooling
should be taken into consideration.
Cold aisle
Hot aisle
050.7385
Classic DC cooling management comes under
pressure. Data center operators must find new
ways to make «green data centers» a reality.
Energy costs and legal regulations are also
necessitating action.
www.rdm.com/bladeshelter/
BladeCooling Plus from R&M Tecnosteel
Robert Merki | CTO
robert.merki@rdm.com
050.7148
030.7914
10|2023–65 CONNECTIONS | 13