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CTV-PRC007-EN28
Selection
The CenTraVac
™
centrifugal chiller
product line provides more than 200,000
individual unit selections over a capacity
range of 170 through 3500 tons. Chiller
selections and performance data can be
obtained through the use of the
CenTraVac chiller selection program
available in local Trane sales offices. This
program can provide a list of chiller
selections optimized to closely match
specific project requirements. Nominal
data and physical data for typical
compressor-evaporator- condenser
combinations are given by product
family.
Trane Model Number
The Trane model number defines a Trane
CenTraVac with its particular component
combination. These components along
with the project design conditions are
required to determine chiller
performance from the CenTraVac
computer selection program:
•
Compressor size and voltage
•
Evaporator bundle size, bundle length,
and number of water passes
•
Condenser bundle size, bundle length,
and number of water passes
•
Leaving chilled water temperature,
evaporator water flow rate,
temperature drop through the chiller
•
Entering condenser water temperature,
condenser water flow rate, and
temperature rise through the
condenser
•
Water side fouling factors for the
evaporator and condenser
•
Refrigerant type for operating on
HCFC-123.
Performance
The CenTraVac computer selection
program provides performance data for
each chiller selection at the full load
design point and part load operating
points as required.
The Trane computer selection program
is certified by ARI in accordance with ARI
Standard 550/590. To assure that the
specific chiller built for your project will
meet the required performance, and to
ensure a more troublefree start-up, it is
recommended that the chiller be
performance tested.
The CenTraVac computer selection
program has the flexibility to select
chillers for excessive field fouling
allowances.
Fouling Factors
ARI Standard 550/590 includes a
definition of clean tube fouling.
Recommended field fouling allowances
have not changed on a relative basis; the
standard fouling adjustment is a 0.0001
increment from 0.0000 “clean” on the
evaporator and 0.00025 increment from
0.0000 “clean” on the condenser.
Chiller specifications should be
developed using the most current
standard fouling factors.
It should be noted that changing the
number of water passes or water flow
rates may significantly alter the
performance of a particular chiller.
To obtain the maximum benefit from the
wide range of selections available,
designers are encouraged to develop
performance specifications and use the
computer selection program to optimize
their selections. This will allow the
selection of the particular compressor-
evaporator-condenser combination
which most closely meets the job
requirements. All selections should be
made by using the computer selection
program.
Unit Performance With Fluid Media
Other Than Water
CenTraVac chillers can be selected with a
wide variety of media other than water.
Typically used media include ethylene
glycol or propylene glycol either in the
evaporator, condenser or both. Chillers
using media other than water are
excluded from the ARI 550/590
Certification Program, but are rated in
accordance with ARI 550/590. Trane
factory performance tests are only
performed with water as the cooling and
heat rejection media. For media other
than water, contact the local Trane sales
office for chiller selections and
information regarding factory
performance testing.
Flow Rate Limits
Flow rate limits for all pass combinations
for evaporators and condensers are
tabulated in the data section for the
appropriate chiller family. For
applications outside of these limits,
contact your local Trane office.
Selection
Procedure