Specifications
Designing a Liebert XD Solution
15
Example
For example, a 2000 ft
2
server room with has 30 racks, 15 racks produce 20kW of heat each and 15
produce 10kW of heat per rack.
1. Calculate the total sensible cooling load.
15 racks x 20kW/rack = 300kW
15 racks x 10kW/rack = 150kW
300kW + 150kW = 450kW
The total room load is 450kW.
2. Check heat density per square foot:
450kW/2000ft
2
= 0.225kW/ft
2
= 225W/ft
2
3. Determine base cooling requirements:
Typically, perimeter cooling accounts for 2 to 5kW per rack.
2kW x 30 racks = 60kW
Based on 2kW/rack, 60 kW will be handled by the perimeter cooling.
4. Determine Liebert XD cooling requirements:
450kW - 60kW = 390kW
Three Liebert XDP160s would be needed.
5. Calculate the Liebert XDP reserve capacity:
390kW/3 Liebert XDP160s = 130kW
Each Liebert XDP, on average, would bear 130kW of the heat load.
130kW / 160kW = 81% of maximum load
This Liebert XD solution has 19% reserve capacity.
3.3 Selecting Liebert XD Cooling Modules
The next step is to select the Liebert XD cooling modules to be configured into the solution. Liebert
XD modules that use pumped refrigerant can be connected to the same Liebert XDP/Liebert XDC pip-
ing circuit. This includes the Liebert XDCF, Liebert XDH, Liebert XDO, Liebert XDR and
Liebert XDV.
Generally, the Liebert XDO is selected for use in new installations or renovations where the unit can
be installed on the ceiling or in the overhead space.
The Liebert XDV is designed to permit mounting directly on top of an equipment cabinet, for ease of
installation in existing facilities. The Liebert XDV may also be suspended from overhead, using suit-
able mounting methods.
The Liebert XDCF is a self-contained module designed to cool Egenera’s BladeFrame EX cabinets and
equipment without exhausting heat into the room. Two modules may be mounted on the rear of a
BladeFrame cabinet.
The Liebert XDH is installed among equipment cabinets and is particularly suited for new installa-
tions.
The Liebert XDR replaces the rear door of an equipment cabinet.
Example
Continuing the preceding data center example (in 3.2 - Calculate the Heat Load to be Handled
by Liebert XD System) of a server room 2000 ft
2
with 30 racks (15 producing 20kW of heat per rack
and 15 producing 10 kW of heat per rack), the three Liebert XDPs required can supply coolant to var-
ious types of Liebert XD modules. For instance, the racks with 20kW per rack could be cooled with