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CTV-PRC007-EN
Design Simplicity
Impellers are keyed directly to the motor
shaft for high reliability and performance
and low life-cycle costs.
Reliable Motor Cooling
The motor is engulfed in liquid
refrigerant to provide efficient, complete
cooling at all load conditions. This
system is reliable and easy to maintain.
Fixed Orifice Flow Control
For proper refrigerant flow control at all
load conditions, the CenTraVac design
incorporates the Trane patented fixed
orifice system. It eliminates float valves,
thermal expansion valves and other
moving parts. Since there are no moving
parts, reliability is increased.
Quiet Operation
With only one moving component — the
rotor and impeller assembly — the Trane
low speed, direct drive design operates
exceptionally quietly. The smoothly
rotating CenTraVac compressor is
inherently quieter than other compressor
types. Typical CenTraVac chiller sound
measurements are among the quietest in
the industry. Trane can guarantee sound
levels with factory testing and
measurements in accordance with
ARI standard 575.
The Reliability Standard
Just as a multi-stage turbine is more
efficient than a single stage turbine, the
CenTraVac multi-stage compressors are
more efficient and reliable than single-
stage designs.
Direct Drive Design — No Gear Losses
The direct drive compressor operates
without speed increasing gears, thus
eliminating gear energy losses.
Compressors using gears suffer mesh
losses and extra bearing losses in the
range of three to five percent at full load.
Since these losses are fairly constant
over the load range, increasingly larger
percentage losses result as load
decreases.
Multiple Stages of Compression
The compressor operates more
efficiently over a wide range of
capacities, virtually eliminating the need
for energy wasting hot gas bypass as
typically found on single stage chillers.
The radial component of velocity
determines the ability of the chiller to
resist interruption of smooth refrigerant
flow when operating at light loads and
with high condensing temperatures. This
interruption in flow and unstable
operation, called “surge” is avoided with
the two-stage design.
Inlet Guide Vanes
Part load performance is further
improved through use of moveable
designed variable inlet guide vanes. Inlet
guide vanes improve performance by
throttling refrigerant gas flow to exactly
meet part load requirements and by
prerotating refrigerant gas for optimum
entry into the impeller. Prerotation of
refrigerant gas minimizes turbulence and
increases efficiency.
Two-Stage Economizer
The CVHE/CVHG CenTraVac chiller has a
two-stage economizer — providing up to
seven percent greater efficiency than
designs with no economizer. Since the
CVHE/CVHG uses three impellers, it is
possible to flash refrigerant gas at two
intermediate pressures between the
evaporator and condenser pressures,
significantly increasing chiller efficiency.
This improvement in efficiency is not
possible in single-stage chillers since all
compression is done by one impeller.
Single Stage Economizer
The CVHF CenTraVac chiller has a single-
stage economizer — providing up to 4
1
/2
percent greater efficiency than designs
with no economizer.
Since the CVHF CenTraVac uses two
impellers, it is possible to flash
refrigerant gas at an intermediate
pressure between the evaporator and
condenser pressures, significantly
increasing chiller efficiency. This
improvement in efficiency is not possible
in single-stage chillers since all
compression is done by one impeller.
Features and
Benefits
The CenTraVac
™
Chiller Operating Cycle
Refrigeration
Cycle