Specifications

Factory-Mounted Starter (Optional) — The starter
allows for the proper start and disconnect of electrical en-
ergy for the compressor-motor, oil pump, oil heater, and con-
trol panel.
Storage Vessel (Optional) — There are 2 sizes of
storage vessels available. The vessels have double relief valves,
a magnetically-coupled dial-type refrigerant level gage, a
one-inch FPT drain valve, and a
1
⁄ 2 -in. male flare vapor
connection for the pumpout unit.
NOTE: If a storage vessel is not used at the jobsite, factory-
installed isolation valves on the chiller may be used to iso-
late the chiller charge in either the cooler or condenser.
An optional pumpout system is used to transfer refrigerant
from vessel to vessel.
REFRIGERATION CYCLE
The compressor continuously draws refrigerant vapor from
the cooler, at a rate set by the amount of guide vane opening
(Fig. 3). As the compressor suction reduces the pressure in
the cooler, the remaining refrigerant boils at a fairly low tem-
perature (typically 38 to 42 F [3 to 6 C]). The energy re-
quired for boiling is obtained from the water flowing through
the cooler tubes. With heat energy removed, the water be-
comes cold enough for use in an air conditioning circuit or
process liquid cooling.
After taking heat from the water, the refrigerant vapor is
compressed. Compression adds still more heat energy and
the refrigerant is quite warm (typically 98 to 102 F
[37 to 40 C]) when it is discharged from the compressor into
the condenser.
Relatively cool (typically 65 to 90 F [18 to 32 C]) water
flowing through the condenser tubes removes heat from the
refrigerant, and the vapor condenses to a liquid. Further re-
moval of heat from the refrigerant occurs in the lower cham-
ber of the condenser, which is called the sensible subcooler.
At this point, the liquid refrigerant is subcooled by contact
with the coolest (entering water) condenser tubes.
After leaving the sensible subcooler section of the con-
denser, the liquid refrigerant enters the float valve chamber.
The main float valve maintains a liquid level in the sub-
cooler to prevent hot gas bypass from the condenser to the
cooler at part load conditions. A second valve in the float
valve chamber opens at part load conditions when the liquid
level increases in the condenser to bypass liquid from the
float chamber directly to the cooler inlet. The liquid refrig-
erant from the main float valve then flows into the turbine
housing chamber on the compressor. The liquid refrigerant
passes through the turbine nozzles and impacts the turbine
blades where energy is reclaimed as the refrigerant expands
through the turbine to the lower cooler pressure. The turbine
wheel is attached to the motor shaft which allows the turbine
to supplement and reduce motor power requirements. At this
point the refrigerant flashes to a mixture of gas and liquid
which removes heat from the remaining liquid. This mixture
flows back to the cooler where it is now at the same tem-
perature and pressure at which the cycle began.
MOTOR AND LUBRICATING OIL
COOLING CYCLE
The motor and the lubricating oil are cooled by liquid re-
frigerant taken from the bottom of the condenser vessel
(Fig. 3). Refrigerant flow is maintained by the pressure
differential that exists due to compressor operation. After the
refrigerant flows past an isolation valve, an in-line
filter, and a sight glass/moisture indicator, the flow is split
between the motor cooling and oil cooling systems.
Flow to the motor cooling system passes through an ori-
fice and into the motor. Once past the orifice, the refrigerant
is directed over the motor by a spray nozzle. The refrigerant
collects in the bottom of the motor casing and is then drained
back into the cooler through the motor refrigerant drain line.
The refrigerant outlet from the motor casing is sized to act
as an orifice to maintain a higher pressure in the motor shell
than in the cooler/oil sump. The motor is protected by a tem-
perature sensor imbedded in the stator windings. An in-
crease in motor winding temperature past the motor override
set point overrides the temperature capacity control to hold,
and if the motor temperature rises 10° F (5.5° C) above this
set point, closes the inlet guide vanes. If the temperature rises
above the safety limit, the compressor shuts down.
Refrigerant that flows to the oil cooling system is regu-
lated by thermostatic expansion valves (TXVs). The TXVs
regulate flow into the oil/refrigerant plate and frame-type heat
exchanger (the oil cooler in Fig. 3). The expansion valve
bulbs control oil temperature to the bearings. The refrigerant
leaving the oil cooler heat exchanger then returns to the chiller
cooler.
LUBRICATION CYCLE
Summary —
The oil pump, oil filter, and oil cooler make
up a package located partially in the transmission casting of
the compressor-motor-turbine assembly. The oil is pumped
into a filter assembly to remove foreign particles and is then
forced into an oil cooler heat exchanger where the oil is cooled
to proper operational temperatures. After the oil cooler, part
of the flow is directed to the gears and the high speed shaft
bearings; the remaining flow is directed to the motor shaft
bearings. Oil drains into the transmission oil sump to com-
plete the cycle (Fig. 4).
Details — Oil is charged into the lubrication system through
a hand valve. Two sight glasses in the oil reservoir permit oil
level observation. Normal oil level is between the middle of
the upper sight glass and the top of the lower sight glass
when the compressor is shut down. The oil level should be
visible in at least one of the 2 sight glasses during operation.
Oil sump temperature is displayed on the CVC (Chiller
Visual Control) default screen. During compressor opera-
tion, the oil sump temperature ranges between 125 to 150 F
(52 to 66 C).
The oil pump suction is fed from the oil reservoir. An
oil pressure relief valve maintains 18 to 25 psid (124 to
172 kPad) differential pressure in the system at the pump
discharge. This differential pressure can be read directly from
the CVC default screen. The oil pump discharges oil to the
oil filter assembly. This filter can be closed to permit
removal of the filter without draining the entire oil system
(see Maintenance sections, pages 66-71, for details). The oil
is then piped to the oil cooler heat exchanger. The oil cooler
uses refrigerant from the condenser as the coolant. The re-
frigerant cools the oil to a temperature between 120 and
140 F (49 to 60 C).
7