Trane Centrifugal Water Chillers CVGF - Manual (Page 24)

Trane CVGF packaged centrifugal water chillers using HFC-134a refrigerant consist of a hermetic
two-stage, gear-drive centrifugal compressor, evaporator, condenser, interstage economizer, unit-
mounted microprocessor based control panel and compressor motor starter. The chiller is entire
factory assembled.
Compressor
Two-stage centrifugal compressor with high-strength aluminum alloy, fully shrouded impellers.
The impellers are tested at 25 percent over-design operating speed. The rotating assembly is
dynamically balanced for vibration of less than 5.1 mm/s (0.2 ips peak velocities) at nominal
operating speeds. The control system affords and admitted 100 - 20 percent capacity modulation
by electrically actuated guide vanes upstream of each impeller.
Drive Train
The drive train consists of helical bull and pinion gears. Gear tooth surfaces are case hardened
and precision ground. The one-piece impeller shaft is supported by hydrodynamic thrust and radial
bearings.
Motor
The motor is a hermetic, liquid-refrigerant cooled, two-pole, low-slip, squirrel-cage induction
motor. A radial hydrodynamic bearing and duplex angular contact ball bearings support the rotor
assembly. Winding-embedded sensors provide positive thermal protection.
Lubrication System
The lubrication system consists of an internal oil sump with heaters, positive displacement oil
pump, brazed plate condenser-cooled oil cooler, and oil distillation/return line.
Economizer/Orifi ce
The economizer consists of a carbon steel shell with internal components designed to prevent
liquid carryover to the compressor. Liquid refrigerant is admitted through a single calibrated orifi ce
(no moving parts) which maintains a pressure differential between condenser and economizer.
Evaporator
The evaporator is designed, tested and stamped in accordance with ASME Boiler and Pressure
Vessel Code or PED (European Code) for refrigerant side working pressure of 15.2 bars (220psig).
It consists of a carbon steel shell with steel tube sheets welded to eachend. Intermediate tube
support sheets positioned along the shell axis prevent relative tube motion. Individually-replaceable
externally-finned and internally-grooved 19 mm (¾ in.) and 25.4 mm (1.0 in.) nominal diameter
seamless copper tubes are mechanically expanded into tube sheets.
Two- or three- pass water boxes rated at 10.5 bar (150 psi) is standard. Grooved pipe connections
are standard; fl anged connections are optionally available. The waterside is hydrostatically tested at
ASME 1.5 times, PED 1.43 times, GB 1.25 times maximum working pressure.
Liquid refrigerant is admitted to the evaporator through a single calibrated orifi ce (no moving parts)
which maintains a pressure differential between the economizer and the evaporator.
24 CTV-PRC001-E4
Mechanical Specifi cations