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April 18
Implementation possibilities
for efficient cooling of 19” cabinets
By Nicole Jeroschewski,
Heitec
This article clearly shows
the demand for good planning of
cooling solutions in the cabinet area.
This is no longer just about planning
to be as cost-efficient as possible.
Electronics and with it the dissipation
of heat from the cabinet becomes
more and more complex.
It is no longer sufficient to take
a look at the investment costs only.
The miniaturization of electronic compo-
nents always results in the generation of heat
in devices and thus in 19 “cabinets. More and
more components are being installed in nar-
rower spaces, but the heat loss performance of
the individual modules is usually not reduced
accordingly. On the contrary, miniaturization
is creating more and more power dissipation in
ever smaller spaces. This leads to a continuous
heat development in the cabinet. The result is
shortened lifetime of the components due to
excessive heat stress. Electronic components
installed in a 19 “cabinet are generally designed
for amaximumoperating temperature of 50 °C.
The lifetime already doubles when the prevail-
ing temperature is reduced by 10 °C. Therefore,
cooling – whether passive or active – is essential
for most applications today. There is a myriad
of cooling solutions, which is why one has to
choose from case to case which of these solu-
tions brings decisive advantages for the respec-
tive application. The use of air/water heat
exchangers is an option to cool cabinets. But
also, the use of various cabinet coolers, such as
side climate modules, roof-mounted cooling
units or fan trays is a common approach to get
cool air to the electronics and the heat out of
the cabinet.
With air/water heat exchangers, the highest
cooling performance can be achieved in the
smallest possible space. The cooling of the air
inside the server cabinet is executed in such a
way that the power dissipation from the cab-
inet is released via the heat exchanger to the
water and led to the outside. This way, a cooling
performance of up to 10kW can be achieved.
The maintenance effort of this cooling solution
is relatively low, but with the use of air/water
heat exchangers, high infrastructure require-
ments are associated, which of course have
an impact on the costs. IP protection of these
devices is usually at an IP value of 55, which
provides a fairly high level of protection.
Side climate modules are used in cabinets spe-
cially prepared for this purpose – therefore,
the installation is not possible at any time in
any control cabinet and the installation costs
are also not negligible. However, these air
conditioning units produce a cooling perfor-
mance of up to 3.5kW and are thus accom-
panied by a cooling potential that is not to
be underestimated and which is required in
many applications.
Roof-mounted fans are often used in cabinets
when the warm exhaust air is to be sucked up
and blown out of the server rack. These are
very efficient in their cooling performance,
but their installation is partly cost-intensive
and furthermore, hotspots (air areas with
conspicuously high temperatures), which pre-
dominate directly in the cabinet, are not pre-
vented very reliably. However, the advantages
of roof fans are obvious when it comes to sav-
ing space in the cabinet itself. With 43, the IP
protection of roof fans is in the middle range.
Fan trays have the advantage that they can be
used specifically where the heat must be dis-
sipated – so, hotspots can be directly cooled
or prevented. However, it has to be accepted
that one or the other height unit in the cabi-
net is used up for it. If the heat generation in
the cabinet is manageable, it is not necessary
to deploy an expensive cooling solution. Often
complex cooling solutions are needed, which
are accompanied by an expensive infrastruc-
ture. Nevertheless, for certain application areas,
using a simple fan module is still the best solu-
tion. In most cases it can be retrofitted easily in
the cabinet and is often also the much cheaper
alternative. Therefore, before installing expen-
sive cooling solutions, one should always think
about how much cooling power is actually
needed. With an IP protection value of 20, the
protection performance is rather low. But since
fan trays are installed directly in the cabinet,
the protection that the cabinet itself offers is
more important at this point.
With a review of the various cooling options
that can be found, one quickly realizes that
there is rarely a blanket statement to ensure
that there is a cooling solution for cabinets
