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INTRODUCTION
This bulletin describes the operating characteristics,
design features, and application requirements for all
™
Copeland
Scroll
compressors
applications using CO
2
operation. For additional information, please refer to the
online product information accessible from the Emerson
website at Emerson.com/OPI.
Increasing
environmental
potential
direct
emissions
refrigeration systems into the atmosphere have led
system designers to revisit refrigerant R-744 (CO
comparison with HFC refrigerants, the specific
properties of CO
require changes in the design of the
2
refrigeration system. The ZO range of Copeland
Scroll compressors has been designed to exploit the
characteristics of CO
2
efficiency, reliability and liquid handling advantages
of Copeland Scroll technology make it ideal for these
applications.
The
comparably
high-pressure
thermodynamic properties of the refrigerant CO
driven system designers towards low temperature
cascade systems, where CO
expanding refrigerant in the low temperature stage. In
these subcritical cascade applications, the CO
compressor in the low temperature stage is still exposed
to pressure levels higher than in standard HFC-based
systems. However, they are limited to pressure levels
like
those
already
known
applications with refrigerant R-410A. An HFC refrigerant
is typically used in the medium temperature stage of the
cascade system.
The challenges for CO
compressors compared to HFC
2
compressors lie in the high-pressure levels, the higher
mass flow for a given displacement, and designing for
proper lubrication. In terms of mechanical strength, ZO
scroll compressors benefit from many years of
experience with R-410A air-conditioning compressors,
which operate at similar pressure levels as CO
compressors.
CO
FOR LOW TEMPERATURE APPLICATIONS
2
SUB-CRITICAL DX SYSTEM
Figure 1 at the end of this bulletin shows a cascade
system diagram with HFC refrigerant for the high side
and sub-critical CO
for the low stage refrigerant.
2
Nomenclature
The model designation contains the following technical
information about the compressor:
© 2017 Emerson Climate Technologies, Inc.
for
refrigeration
(R-744) for a subcritical
concerns
about
from
HFC-based
2
refrigeration systems. The
level
have
2
is used as a direct
2
from
air-conditioning
ZO D 34 K 3 E - TFD - 269
Z =
Compressor family: Scroll
O =
Refrigerant: R744, subcritical operation
D=
Digital Model; Blank= Standard Model
34K = Nominal Capacity (KBTU/HR)
3 =
Model variation
E =
Oil type: POE oil
TFD = Electrical Description:
T= Three Phases
the
F= Internal Inherent Motor Protection
5,7,D & E = Nominal Voltage Range
269 = Bill of material
). In
Please
refer
Emerson.com/OPI
Refer to Table 1 for a detailed list of ZO Family Models.
Approved Oils & Refrigerants
Recommended quality for carbon dioxide purity
grade is 4.0 [(≥ 99.99 %) H2O≤10ppm, O2≤10ppm,
N2≤50ppm] or higher.
and
Emkarate RL 68 HB is approved for new and service
applications. Oil recharge values can be taken from
Copeland Scroll compressors brochures or Copeland™
Products Selection Software.
2
CAUTION
The compressor superheat at suction should be
controlled such that it is always above 36°F (2.2 °C)
to avoid oil dilution in the compressor but low return
gas temperature enough to keep the compressor
discharge temperature below 250°F (121.1°C),
especially
at
condensing and low evaporating temperatures).
Note: A separate heat-exchanger may be required
to maintain the recommended superheat.
2
Refer to Table 2 for reference.
Mounting Parts
Specially designed rubber grommets are available for
mounting (Kit 527-0157-00). These grommets are
formulated from a high durometer material specifically
designed for refrigeration applications. The high
durometer limits the compressors motion thereby
minimizing potential problems of excessive tubing
stress. Sufficient isolation is provided to prevent
vibration from being transmitted to the mounting
4
to
Online
Product
Information at
for details.
high
compressor
ratios
(high
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