April 18
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mbedded
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omputing
which is always cost and energy efficient.
Therefore, an accurate analysis of the appli-
cation is generally unavoidable. Factors such
as the required IP protection and the required
cooling performance are the values that
should be looked at in more detail firstly.
The type of cooling solution that should be
used also depends on other factors, such as
the ambient temperature and the maximum
permissible internal temperature of the cab-
inet. The ambient temperature has a decisive
influence on the heat or the effective cooling
in the cabinet. Temperature changes in the
environment are detectable inside the cabinet
one to one. Therefore, if possible, the cabinet
should be set up in a place with lower ambi-
ent temperature, to keep the energy expendi-
ture for the air conditioning as low as possible
and in consequence, to keep the operating
costs low as well. This logically results in the
installation location. As expected, the most
favorable thermal conditions arise for a free-
standing single cabinet, so that heat can be
emitted to the environment through all free
surfaces via radiation and convection.
The component compactness – the distance of
the components in the cabinet to each other –
also plays a significant role in the heat devel-
opment in the cabinet and in the emergence
of so-called hotspots. Thus, in any case precise
planning of positioning not only makes sense
from a purely functional perspective. Fur-
thermore, care must be taken to ensure that
no bulky and large-scale components impede
the suction of hot air from the interior of the
cabinet to the outside, thus preventing undis-
turbed influx of cold air into it. In principle,
cold air flow of all cooling solutions should
always be directed near the most powerful
components because the greatest power dissi-
pation – and thus the most heat – is produced
there. This arrangement ensures that the cold
air supply from the deployed cooling solution
directly reaches the components without any
loss and cools them optimally.
So, not only the choice of the cooling solution
needs to be considered. Many factors play an
important role. But if you have opted for a
cooling solution, it is important to ensure that
the air flows are guided accurately and that
air circulation is optimized. Not only is this
arrangement proven to save energy, which
makes a significant contribution to environ-
mental protection in about 3.5 million active
control cabinets in Germany – investment
and operating costs can also be reduced to a
minimum by precisely planning the cooling
solution. The selection of individual compo-
nents can play a decisive role. This is the rea-
son why cooling solutions with low energy
consumption are becoming more and more
attentive. Even if the investment costs of these
components in an energy-saving variant are
usually slightly higher than the conventional
components, they amortize themselves after a
short period of time and are often even the
more cost-saving alternative.
The optimal internal temperature of the cab-
inet is normally at +35°C. It makes no sense
to adjust the temperature lower, because at
a lower temperature there can be a signifi-
cant condensation development in the cabi-
net. In addition, the devices and components
forming condensate after cooling has been
switched off or the door of the cabinet has
been opened are getting undercooled. With
its HeiCool Eco for installation in a 19 “cab-
inet or carrier, Heitec has dedicated itself to
the development of a particularly energy- and
thus cost-saving fan tray. With just about one
quarter of the energy consumption of a con-
ventional fan tray on the market, it is truly
beneficial for the user despite its marginally
higher purchase price. With a standard price
of approximately €0.2 per kWh and an energy
saving ratio of 79%, the additional cost for the
Eco fan tray is already amortized after about
16 weeks and the use of this cooling solution
continues to pay off with every operating hour
the HeiCool Eco is in use. This can be deci-
sive from an economic point of view – and in
addition to considerable cost savings, compa-
nies are making a significant contribution to a
positive carbon footprint. Because it is para-
doxical – the components in use are becoming
more and more efficient, but the cooling solu-
tions required for this have to become more
and more powerful, which at the same time
makes them very energy hungry. The housing
of the HeiCool Eco is made of a high-strength
aluminium alloy – which is why the fan tray is
also suited for use in the railway sector - and
impresses with its high-quality optics and the
special design of the air vents. The three ener-
gy-saving fans, with an energy consumption
of just 4.4W per fan, are particularly low in
energy consumption and with a flow rate of
175m³/h in the 230VAC version they are also
still at the level of comparable conventional
fans. If, for example, the cabinet needs to be
cooled by 25K, the fans will be able to cope
with a power loss of about 1400W. HeiCool
Eco is available for various installation situa-
tions. In addition to a 19” variant for the con-
ventional assembly in a 19” cabinet, there is
also a version as a slide-in variant, in which
the fan tray can be easily inserted and pushed
out of the cabinet on a high-quality alumin-
ium frame anytime.
As a specific accessory, a thermostat (adjust-
able switch-on temperature for the fans) has
also been included in the HeiCool program.
Air deflectors for intelligently guiding the air
flows in the cabinet complete the accessories
program.With them, partial streams of cold air
can be routed from front to back into thermally
critical component space to avoid hotspots. In
practice, the function of the air deflectors is
such that cold air is sucked in upfront and
passed through the subrack. The heated air is
then expelled at the rear. These accessories, like
the HeiCool Eco itself, are entirely dedicated to
the topic of energy efficiency. With them and
the thermostat, cooling is aimed to be possible
wherever specifically necessary. This not only
makes a decisive contribution to the protection
of the environment – the purse is significantly
disburdened as well.
Adding to the accessories program of Heitec
Electronics, there is fan monitoring that
reports when one or more fans are no lon-
ger working, and a fan control, which is suit-
able for use in fan trays, among other things.
The fan control offers a variety of functions.
For example, temperature thresholds can be
defined, from which the fans are given a cer-
tain rotational speed. Other functions include,
for example, an alarm when the maximum
temperature is exceeded, as well as a status
request via an integrated I²C bus. The mod-
ules for monitoring and control can be used
for project-specific purposes in systems of
completely different dimensions and require-
ments, too.
n
The electromagnetic compatibility of the cooling is also verified in the course of product release.
