Danfoss TG230 Series, Installation Manual

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Page 59 of 108
M-AP-001-EN Rev. N
System Design Guidelines
In addition to the instructions detailed in the TT and TG series technical documentation set,
this section provides basic guidelines and requirements for the design and manufacture of
R134a systems equipped with DTC compressors.
Refer to the applicable DTC technical manual for applications, operating, installation, and
commissioning instructions.
NOTE
The compressor internal safety control settings are designed to provide protection for the compressor only. Designers MUST
provide SYSTEM protection within their control design. DTC will not be responsible for system protection other than the
compressor.
13.1 General
Requirements
1. Check for compliance with all installation, operating, commissioning and service steps,
as outlined in the documentation set. Check for the appropriate operating envelope
and minimum unloading capacity for the intended application.
2. System components such as evaporators, condensers, valves, etc., should be properly
selected and sized for appropriate performance and compatibility with applied
refrigerant.
3. The system suction and discharge piping should be properly designed and selected for
minimum pressure drop. Since the Turbocor compressor operates without lubricating
oil, conventional piping considerations that ensure oil return, such as multiple risers
and traps, are not required. In most cases, larger diameter lines will result in better
compressor performance and efficiency.
4. For improved efficiency and better control, particularly at low load / low compression
ratios, electronic expansion valves (EXVs) are strongly recommended. To take
advantage of low pressure ratio operation to improve low load performance and
efficiency, EXV capacity should be selected accordingly. Thermal expansion valves
(TXVs) are not recommended due to the general inability of these devices to
adequately cover the operating spectrum of centrifugal compressors, particularly at
low compression ratios.
5. Take all necessary precautions to prevent any possibility of liquid floodback to the
compressor. This means consideration during the ON and OFF cycles, particularly in
multiple compressor installations. This WILL include, but is not limited to, the inclusion
of a liquid line solenoid valve and piping, evaporator and condenser arranged in a
manner that prevents free drainage of liquid to compressor.
6. The refrigeration piping system must be clean and free of all debris in accordance with
refrigeration-industry best practices Particles can damage the compressor.
7. The system control should not be designed based on pump down cycle. The system
cannot be pumped down due to the surge characteristics of centrifugal compressors.
8. Use Table 13-1 for recommended minimum pipe sizes.
13 System Design
Guidelines