FORM 160.77-O2
ISSUE DATE: 11/15/2011
JOHNSON CONTROLS
10
SECTION 1 - YKEP CHILLER OVERVIEW
YKEP OIL MANAGEMENT
Figure 4 on Page 11 shows the layout of the chiller
oil management system. Each compressor has a dedi-
cated oil pump in a common oil sump with the other
pump. Oil for each is passed through its individual
oil cooler and filter set to the compressor bearings.
Each compressor has supervisory pressure monitoring
against the sump pressure to ensure sufficient supply to
its bearings. Refrigerant liquid flow to each oil cooler
is regulated with a thermostatic expansion valve sens-
ing oil temperature at the outlet of the cooler to 110° F.
Oil drains from the rotor support of each compressor
back to the sump. Oil to each compressor fills a drain-
down reservoir in the housing to provide coastdown oil
in the event of a power loss while running.
Oil temperature is maintained to a target 50° F above
condenser saturation temperature when the chiller is
not running. Electric oil heaters are operated by the
control system to accomplish this. At no time will the
control allow the oil heaters to continue to operate with
oil temperature above 160°F.
Oil return from the refrigerant system is accomplished
with a single eductor block. The block has three pas-
sages with eductor nozzles, all driven by condenser gas
from a common manifold within the block.
The venturi stream of each of the nozzles draws fluid
from:
• the evaporator
• the primary compressor PRV cavity in two adja-
cent locations
• the economizer compressor PRV cavity.
The outlet of the eductor sections goes to a common
plenum in the block and vented to the oil sump. The oil
sump is vented to the suction of the Primary compres-
sor behind the pre-rotation vanes.
The primary compressor is also supplied with liquid
refrigerant gear cooling that is initiated with a solenoid
valve that opens for compressor run.
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