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1.9 Subcooling Correction
Performance rating tables for the 06CC models are
developed assuming that the liquid temperature is at 40 F
(4 C). If the design liquid temperature is other than 40 F
(4 C), corrections of the estimated performance may be
accomplished by the following methods:
1. For R-22 and R-407A, decrease compressor capac-
ity (as shown in the published performance data) by
3% for each 10°F (12°C) increase in liquid refrigerant
temperature (measured entering the expansion
valve).
2. For R-404A/R-507, decrease compressor capacity
(as shown in the published performance data) by 6%
for each 10°F (12°C) increase in liquid refrigerant
temperature (measured entering the expansion
valve).
3. Calculate the change in refrigerant enthalpy at the
new liquid temperatures and multiply that by the
mass flow rate (as shown in the published perfor-
mance data). Mass flow rates in the 06CC models
have very small fluctuations based on liquid tempera-
tures because they operate near their maximum vol-
umetric efficiency.
1.10 Subcooler Load
Carlyle offers brazed-plate heat exchangers for use on
single and multiple compressor systems. These heat
exchangers should be sized based on the estimated sub-
cooling load. A listing of the available heat exchangers is
provided in the “6.0 Compressor Accessories” section of
this document. The subcooler load may be estimated by
any of the following methods:
1. The subcooling load for R-22 and R-407A systems is
approximately equal to 25 to 30 percent of the com-
pressor capacity for the given condition. The sub-
cooling load for R-404A/R-507 systems is
approximately equal to 35 to 40 percent of the com-
pressor capacity for the given condition.
2. The actual subcooling load may be calculated by
multiplying the compressor mass flow rate by the
change in liquid enthalpy (between entering and
leaving liquid temperature) across the subcooler.
3. Carlyle’s Solutions Software calculates the subcooler
load for the system designer.
1.11 Discharge Pressure Limits
Two-stage 06CC models may be applied in systems that
utilize air-cooled condensers. Carlyle limits the maximum
design saturated discharge temperature in these systems
to 130 F and the minimum design saturation discharge
temperature to 70 F. Allowing saturated discharge tem-
peratures to fall below 70 F does not significantly affect
energy usage, is not recommended, and may lead to
increased valve stresses and potential valve failure.
1.12 Compressor Discharge Pressure
Control
Stable control of the discharge pressure in the 06CC
models has been shown to significantly increase com-
pressor reliability. Carlyle strongly recommends the use
of a discharge pressure regulators for all R-22 applica-
tions that utilize multiple 06CC models. Carlyle requires
the use of discharge pressure regulators for all R-407A,
R-404A, and R507 applications that utilize multiple 06CC
models. All single 06CC compressor applications require
the use of a discharge pressure regulator. The pressure
regulator must be installed so that the discharge pres-
sure of the compressor will not fall below the 70 F satu-
rated discharge temperatures noted in “1.11 Discharge
Pressure Limits” section. All systems that apply Hot Gas
Defrost designs require the use of a discharge pressure
regulator.
1.13 Variation in Capacity and Power
All 06CC model compressors have relatively small varia-
tions in compressor capacity across the full range of
acceptable saturated discharge temperatures (SDT).
Compressor capacity varies approximately 6% between
the maximum and minimum allowable saturated dis-
charge temperatures (130 F SDT and 70 F SDT, respec-
tively). This small variation in compressor capacity
results in significantly reducing ON/OFF compressor
cycling, when compared to similarly designed single-
stage compressor applications, while still maintaining
very high EERs.
1.14 Superheat Correction
The published 06CC Model Performance tables for
Carlyle’s 06CC models are generated assuming a return
gas temperature (RGT) of 65 F. Designs that have
Important!
Carlyle published 06CC Model Performance Data
assumes that the liquid temperature is at 40 F or
at the Saturated Interstage Temperature (SIT) +
10°F, whichever is higher. These assumptions are
based on the fact that the subcooler cannot oper-
ate at saturated temperatures lower than the suc-
tion of the compressor interstage. The suction of
the subcooler is connected to the interstage
pressure port of the 06CC models which acts to
limit the temperatures that are achievable in the
subcooler. For more detailed information, see the
Interstage Pressure Tables on pages 11-13.
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