Vertiv Liebert XD Series, System Design Manual

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1.9 Liebert XDC—Refrigerant Chiller
The Liebert XDC is an indoor chiller that connects directly to the Liebert XD cooling modules and
provides refrigerant circulation and control. The Liebert XDC keeps the refrigerant temperature above
the room dew point at the sensors. The Liebert XDC contains a refrigerant to refrigerant heat exchanger
along with two tandem scroll compressor circuits. This allows heat rejection to the outdoor ambient air by
using either the air-cooled condensers or water/glycol shell-and-tube condensers much like a standard
computer room air conditioning unit. The Liebert XDC employs two remote sensors (for redundancy) to
determine the temperature and humidity in the air and instantly adjusts refrigerant supply temperature
to compensate for changing conditions.
The Liebert XDC uses the Liebert iCOM®. This advanced control enables the user to monitor essentially
all aspects of the Liebert XD Precision Cooling system, from operating status to maintenance
1.9.1
Liebert XDC
Minimum Load
The Liebert XDC’s minimum recommended operating load is 40% of system nominal capacity. For
example, a Liebert XDC160 60Hz system’s minimum load would be 64 kW. Loading below this value can
unfavorably affect system operation.
Figure 1.10 Liebert XD Chiller
1.10 Liebert XDP—Pumping Unit
The Liebert XDP isolates the building’s chilled water circuit from the pumped refrigerant circuit. The
Liebert XDP circulates refrigerant to Liebert XD cooling modules while preventing condensation by
maintaining the refrigerant’s temperature above the room dew point at the sensors. The Liebert XDP
employs two sets (for redundancy) of remote sensors to determine the temperature and humidity in the
air and instantly adjusts refrigerant supply temperature to compensate for changing conditions.
The Liebert XDP uses the Liebert iCOM. This advanced control enables the user to monitor essentially all
aspects of the Liebert XD Precision Cooling system, from operating status to maintenance.
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