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Selection Procedure |
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The CenTraVac® centrifugal chiller product line
provides more than 200,000 individual unit selections
over a capacity range of 170 through 3000 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.
Examples
Nominal data and physical data for typical compressor-evaporator- condenser
combinations are given by product family.
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. 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 includes a definition of clean tube fouling. Recommended field fouling allowances have not changed on a
relative basis; the standard fouling adjustment is a
0.00025 increment from 0.0000 "clean."
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 Certification Program, but are rated in accordance
with ARI 550. 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. |
