Rittal Liquid Cooling Package
87
18 Frequently Asked Questions (FAQ)
EN
18
Frequently Asked Questions
(FAQ)
In what output ranges is the Rittal Liquid Cooling
Package available?
The cooling output of an air/water heat exchanger is
basically dependent on the inlet temperature and
volumetric flow of the water as well as the air
throughput achieved by the fans which are used. Up
to 30 kW of cooling output is possible. In correctly
assessing the information, it is important to note at
what
Δ
T (temperature differential between server air
inlet and server air outlet) these values were report-
ed. Modern servers such as 1 U-Dual CPU systems
or blade servers can have a
Δ
T of up to 25 °C.
Please note the recommendations of the server
manufacturer.
Are special components required for use with the
Liquid Cooling Package?
All components that follow the "front to back" cooling
principle (99% of IT equipment) may be used with-
out restriction in connection with the Liquid Cooling
Package. Every Rittal server rack which was previ-
ously cooled conventionally may be cooled with a
Liquid Cooling Package after changing to sealed
doors. In other words, it is possible to retrofit stand-
ard racks and bay them onto the Liquid Cooling
Package. The server enclosure remains unaffected
by the side installation of the Liquid Cooling
Package. All height units remain fully usable in their
complete depth. Further, by locating the foam strips
appropriately, sufficient cooling is also possible for
devices which require sideways air throughput (e.g.
switches).
Is the ambient air heated by additional heat coming
out of these enclosures?
The cooling system in the enclosure works com-
pletely independently of the ambient air. All waste
heat is transferred externally through the cooling
water circuit.
May the quantity of heat removed be controlled de-
pendent on the heat loss?
The controlled variable for the Liquid Cooling
Package is the temperature of the air blown in in
front of the 482.6 mm (19") level. The values to be
used here are available in the manufacturer's in-
struction manual. Upon installation, the desired set-
point temperature is set once on the Liquid Cooling
Package. This value will be kept constant, irrespec-
tive of the cooling output demands. This occurs
through the corresponding automatic opening and
closing of the 2-way control valve. Additionally, the
necessary fan output is adjusted based on the dif-
ference between the server-out temperature and the
target temperature. In this manner, the Liquid
Cooling Package always cools only as much as is
necessary without wasting energy. Further, this
avoids problems arising from condensation and
desiccation which results from overcooling.
How is the airflow in the enclosure achieved and what
advantages does this have?
As a general rule, the "front to back" principle is
used in server enclosures. Cold air is supplied to the
front of the enclosure. The units built into the enclo-
sure have their own fans, which draw in this air and
use it internally for cooling. Thus heated, it is ex-
hausted to the rear. The special horizontal air rout-
ing of the Liquid Cooling Package, which is adapted
especially to this widespread cooling principle,
evenly supplies cooled air to the complete height of
the server enclosure. That means that all units, inde-
pendent of their installation position in the enclosure
and their charge state, receive sufficient cold air.
Temperature gradients are avoided, so that an ex-
tremely high cooling output can be achieved for
each enclosure.
Can the LCP Rack be operated with its doors open?
The response of the Liquid Cooling Package upon
operation with opened doors depends chiefly upon
the prevailing ambient conditions. If a front door is
opened, the cool air is mixed marginally with the am-
bient air. Thus, no cooling problems are expected in
air conditioned rooms. Overall, no heat is carried
into the room. The back door should only be opened
for a short while during operation, since this breaks
the cooling air circuit, resulting that the waste heat is
carried into the room. However, this does not influ-
ence the cooling of the units in the enclosure.
Why is the Liquid Cooling Package, as an air/water
heat exchanger, installed on the side panel?
It was important to develop a high performance
cooling system which would also meet the require-
ments of the coming years. This could only be
achieved by routing the cooling air in a manner
which was tailored to the needs of the devices. The
main problem associated with cooling by air from
the raised floor or with top or bottom heat exchang-
ers is air routing. Cold air which is fed into the enclo-
sure from below or above changes its temperature
greatly because of recirculation. Temperature differ-
entials of up to 20 °C were measured from "below" to
"above" in enclosures found in data centres. Thus, a
server installed "below" in an enclosure may have
Note:
This section contains only a selection of the
frequently asked questions (FAQ). Further
FAQs may be found on our website:
www.rimatrix5.com
