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Selection Procedure
12
RLC-PRC005-E4
The chiller capacity tables cover the
most frequently encountered leaving-
liquid temperatures. The tables reflect a
6°C [10.8°F] temperature drop through
the evaporator. For other temperature
drops, apply the appropriate
performance data adjustment factors.
For chilled brine selections, refer to
Figures F-3 and F-4 for ethylene and
propylene glycol adjustment factors.
To select a Trane air-cooled Series R
™
chiller, the following information is
required:
Selection Procedure SI Units
The chiller capacity tables P-1 through
P-4 cover the most frequently
encountered leaving-water
temperatures. The tables reflect a 6°C
temperature drop through the
evaporator
To select a Trane air-cooled RTAC chiller,
the following information is required:
1
Design load in kW of refrigeration
2
Design chilled-water temperature drop
3
Design leaving-chilled-water
temperature
4
Design ambient temperature
Evaporator flow rates can be
determined by using the following
formula:
Lps = kW (capacity) x 0.239 ÷
temperature drop (°C)
To determine the evaporator pressure
drop we use the flow rate (Lps) and the
evaporator water pressure drop Figure
F1.
For selection of chilled brine units, or
applications where the altitude is
significantly greater than sea level or the
temperature drop is different than 6°C,
the performance adjustment factors
from Table F-1 should be applied at this
point.
For example:
Corrected Capacity = Capacity
(unadjusted) x Glycol Capacity
Adjustment Factor
Corrected Flow Rate = Flow Rate
(unadjusted) x Glycol Flow Rate
Adjustment Factor
5
The final unit selection is:
• Quantity (1) RTAA 140
• Cooling capacity = 505.9 kW
• Design ambient temperature 35°C
• Entering chilled-water
temperatures = 12°C
• Leaving chilled-water
temperatures = 7°C
• Chilled-water flow rate = 24.2 Lps
• Evaporator water pressure
drop = 53 kPa
• Compressor power input = 159 kW
• Unit COP = 2.9 kW/kW
Contact the local Trane sales engineer
for a proper selection at the given
operating conditions.
For a selection in English units:
• 1 ton = 3.5168 kW
• Evaporator flow rate in gpm =
24 x tons ÷ delta T (°F)
• Delta T (°F) = delta T (°C) x 1.8
• 1 gpm = 0.06309 Lps
• 1 ft WG = 3 kPa
• EER = COP ÷ 0.293