Refrigerant Lubrication Cycle; Summary; Bearings - Carrier AquaEdge 19DV Series Start-Up, Operation And Maintenance Instructions Manual

CAUTION
To avoid adverse effects on chiller operation, considerations
must be made to condenser water temperature control. For
steady state operation, the minimum operating refrigerant
pressure differential between evaporator and condenser is ap-
proximately 7 psid (48 kPa) with a maximum evaporator re-
frigerant temperature of 65°F (18°C). Consult Chiller Build-
er for required steady state operational limits and low lift op-
tions. Inverted start conditions are acceptable for short
durations of time, but for periods exceeding 5 minutes, a spe-
cial control solution strategy should be used to allow the
chiller to establish a minimum refrigerant pressure differen-
tial (and thereby adequate equipment cooling).

REFRIGERANT LUBRICATION CYCLE

Summary

The 19DV Series chiller uses refrigerant to lubricate the bearings.
The lubrication control is automatically controlled by the chiller
controls. In normal RUN mode refrigerant is pumped by means of
a refrigerant pump from the high side condenser float chamber to
the bearings. Prior to start-up, liquid level in the high side con-
denser float chamber is maintained by pumping refrigerant liquid
EDUCTOR
LEGEND
= PURGE
= LUBE SYSTEM
= MAIN REFRIGERANT SYSTEM
COMPRESSOR
FLOAT CHAMBER
COOLER
Fig. 4 — Refrigerant Lubrication Cycle
8
from the evaporator to the high side float chamber until level sen-
sor is satisfied. If liquid high side float level is not satisfied, the
pump will move refrigerant from the evaporator to the condenser.
During pre-lube and post-lube cycles, refrigerant is drawn from
the evaporator for bearing lubrication.
Figures 4 and 5 identify the refrigerant lubrication assembly. Sup-
ply refrigerant is pulled through a filter drier by the refrigerant
pump and is pumped to the bearings through two protective filters
and then returned to the evaporator.
There are two pressure sensors located across the refrigerant
pump. During RUN mode a minimum of 12 psid is required for
the refrigerant pump delta difference. An alert will trigger if
this value is less than 13 psid while the machine is in normal
operating mode. Consult the 19DV with PIC6 Controls Opera-
tion and Troubleshooting manual for details.

Bearings

The 19DV motor-compressor assembly includes two matched
sets of refrigerant-lubricated bearings. The motor shaft is sup-
ported by a combination set of journal bearing and roller ele-
ment bearings on each end of compressor. The refrigerant lu-
brication pressure difference is defined as the bearing input
pressure minus the bearing output pressure plus the Refrigerant
Delta P Offset.
VENT LINE
PURGE SYSTEM
ECONOMIZER
LOW SIDE
REFRIGERANT
LUBRICATION
SYSTEM
CONDENSER
HIGH SIDE FLOAT
CHAMBER