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AGL_Ref_ST_YFK1E_EN_Rev01
▪
In all systems
: to test liquid floodback and oil dilution, all possible transient operation conditions
in the system should be checked, eg, compressor frequent start/stop, compressor start after long
of f time with migration, defrost, switching between the operation modes in reversible systems,
load changes, f ans or pumps cycling at low load and more. To evaluate the risk of liquid floodback
and oil dilution, please refer to the chart in
Figure 13
.
Figure 13: Oil dilution chart (tb = bottom shell temperature; te = evaporating temperature) and position for oil
temperature sensor
The bottom shell temperature together with the evaporating temperature gives an indication whether
liquid ref rigerant is returning or diluted in the compressor oil sump. The compressor sump
temperature must remain in the (green) safe area, as shown in the oil dilution chart in
Figure 13
. In
case of operation in the (red) unsaf e area, adjustments are required in order to modify the system
design, ref rigerant charge or superheat setting of the expansion device(s). The bottom shell
temperature should be measured accurately. The thermo -probe must be insulated well and
positioned on the opposite side o f the sight glass or at an angle of 90° clockwise f rom the suction
inlet with view on the top.
3.16 Liquid injection
The use of liquid injection is mandatory for all YF*K1E compressors in low-temperature applications
with R404A, R407A, R407F, R448A, R449A, R454C, R455A or R454A. Using liquid injection
technologies is required in order to achieve excellent compressor efficiency and to keep the operation
within saf e limits.
NOTE: All YF*K1E corresponding operating envelopes are based on the use of liquid
injection. For technical data and operating envelopes, see Select software at
www.climate.emerson.com/en-gb/tools-resources
.
Liquid injection is achieved by means of a Discharge Temperature Control (DTC) valve. The DTC
valve is equipped with a custom bulb profile, which must be installed in the top well of the compressor
sensing the temperature closest to the discharge port. The DTC valve only allows injection when
cooling is needed and in the required amount.
The use of an external discharge thermostat is mandatory for all YF*K1E compressor models.
Figure 14: Diagram with liquid injection and DTC valve
