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System Description
1
1.0 SYSTEM DESCRIPTION
The Liebert XD™ family of cooling units delivers efficient, sensible cooling to high-heat environ-
ments. Liebert XD systems are designed to cool computer racks and hot zones in a data center or com-
puter room without taking up expensive floor space for cooling components.
The Liebert XD family includes:
• Liebert XDC—Liebert XD Chiller; cools and pumps refrigerant to cooling modules
• Liebert XDP—Liebert XD Pumping unit; pumps refrigerant to cooling modules
• Liebert XDA—mounts on the rear of the equipment cabinet
• Liebert XDCF—mounts on the rear of an Egenera BladeFrame EX cabinet
• Liebert XDH—Liebert XD Horizontal row cooler; integrated into hot aisle-cool aisle room layout
• Liebert XDO—Liebert XD Overhead unit, suspended from the ceiling structure
• Liebert XDV—Liebert XD Vertical unit; mounted on top of the equipment cabinet or suspended
from the ceiling structure
Systems combining Liebert XDO and Liebert XDV units can remove more than 20 kW (5.7 tons) of
heat per cabinet. A set of Liebert XDCF modules also can remove 20kW (5.7 tons) of heat from an
Egenera BladeFrame EX cabinet. A system with Liebert XDH units can remove more than 30kW
(8.5tons) of heat per rack.
For minimum Liebert XDP and Liebert XDC load recommendations, see 1.8.1 - Liebert XDP Mini-
mum Load; 1.9.1 - Liebert XDC Minimum Load; and Tables 27 and 31.
The Liebert XD system also performs at high efficiency rates. Properly spaced cooling modules and
the Liebert XD system’s fluid phase change technology, combine to reduce a Liebert XD system’s
energy consumption to at least 27 percent less than a traditional cooling system.
The Liebert XD family maintains this energy efficiency by employing the heat absorption properties
of a liquid (pumped refrigerant) through a phase change. Refrigerant is pumped as a liquid, becomes
a gas within the heat exchangers of the cooling modules (either the Liebert XDCF, Liebert XDH, Lie-
bert XDO or Liebert XDV) and then is returned to either the Liebert XDP or Liebert XDC where it
condenses to a liquid. This eliminates the compression cycle required by traditional systems. And, if a
leak were to occur, the environmentally friendly refrigerant would escape as a gas, causing no harm
to critical equipment (see Figure 1). Because no compressor is used in the circuit, no oil is needed.
Figure 1 Pressure enthalpy diagram - refrigerant
Enthalpy
Pressure
Liquid Liquid/Vapor Mix Vapor
Traditional
Vapor
Compression
Cycle
Pumped
Two-Phase
Cycle
XD CoolFrame, XDH,
XDO, XDV