Danfoss Turbocor TT Series, Service Manual

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Chapter 2.0 Compressor Fundamentals
Compressor operation begins with a demand signal applied to the compressor. The startup sequence is
configurable in the startup settings. See the OEM Programming Manual for further details.
2.1 Main Fluid Path
The compressor is a two-stage centrifugal type compressor utilizing variable speed as the principle means of
capacity control with inlet guide vanes (IGVs) assisting when required. Refrigerant enters the first stage suction side
of the compressor as a low-pressure, low-temperature, superheated vapor. It then passes through variable IGVs that
assist compressor control at part-load conditions. Both impellers are mounted on a common shaft. Vapor passes
through the first-stage impeller where velocity energy is added to the refrigerant. This is converted to an
intermediate pressure in the first-stage volute. Vapor then enters the second-stage impeller through a diffuser. In
the second stage, impeller velocity energy is again added to the refrigerant and converted to the final discharge
pressure in the discharge diffuser and volute. From the second-stage impeller, refrigerant passes as a high pressure,
superheated vapor to the system discharge line.
Figure 2-1 Compressor Fluid Paths
Table 2-1 Compressor Fluid Paths
No. Component No. Component
1 Low Pressure/Low Temperature Gas 6 High-Pressure/High Temperature Gas
2 Inlet Guide Vanes (IGVs) 7 Second-Stage Impeller
3 First-Stage Impeller 8 Vaned Diffuser
4 Volute Assembly 9 Vaneless Diffuser
5 Discharge Port 10 De-Swirl Vanes
2.2 Motor and Power Electronics Cooling
Liquid refrigerant, having at least 3.5° Kelvin/ 6.3° Rankine sub-cooling at connection point, must be piped to the
compressor cooling inlet connection. This connection is a 1/2 inch O-ring face seal (ORFS) connection with a built-in
strainer. Refer to Figure 2-2 Cooling Inlet Adapter on page 34 for an example of the cooling inlet adapter.
M-SV-001-EN Rev. H-1/23/2023 Page 33 of 294