Johnson Controls Frick 852 User Manual

RWH ROTARY SCREW COMPRESSOR UNITS
INSTALLATION
070.620-IOM (DEC 12)
Page 10
OIL FILTER(S)
NOTICE
Use of lter elements other than Frick
®
may cause war-
ranty claim to be denied.
The oil lter(s) and coalescer element(s) shipped with the
unit are best suited to ensure proper ltration and operation
of the system.
THERMOSYPHON OIL COOLING
Thermosyphon oil cooling is an economical, effective method
for cooling oil on screw compressor units. Ther mosyphon
cooling utilizes liquid refrigerant at condenser pressure and
temperature that is partially vaporized at the condenser tem
perature in a heat exchanger vessel, cooling the oil to within
35°F of that temperature. The vapor, at condensing pressure,
is vented to the condenser inlet and reliquied. This method
is the most cost effective of all currently applied cooling
systems since no compres sor capacity is lost or compressor
power penalties in curred. The vapor from the cooler need
only be con densed, not compressed. Refrigerant ow to the
cooler is automatic, driven by the thermosyphon principle
and cooling ow increases as the oil inlet temperature rises.
EQUIPMENT  The basic equipment required for a ther
mosyphon system consists of:
1. A source of liquid refrigerant at condensing pressure and
temperature, located in close proximity to the unit to mini
mize piping pressure drop. The liquid level in the refrigerant
source must be 6 to 8 feet minimum above the center of the
oil cooler.
2. An oil cooler heat exchanger (often a plate and shell oil
cooler) designed for the purpose.
Due to the many variations in refrigeration system design
and physical layout, several systems for assuring the above
criteria are possible. Figure 9 illustrates a sample thermo
syphon oil cooling circuit.
Figure 9
SYSTEM OPERATION - Liquid refrigerant lls the cooler shell
side up to the Thermosyphon receiver liquid level.
Hot oil (above the liquid temperature) owing through the
cooler will cause some of the refrigerant to boil and vapor
ize. The vapor rises in the return line. The density of the
refrigerant liquid/vapor mixture in the return line is consid
erably less than the density of the liquid in the supply line.
This imbalance provides a differential pressure that sustains
a ow condi tion to the oil cooler. This relationship involves:
1. Liquid height above the cooler.
2. Oil heat of rejection.
3. Cooler size and piping pressure drops.
The liquid/vapor returned from the cooler is separated in the
receiver. The vapor is vented to the condenser inlet and need
only be reliquied since it is still at condenser pressure (Figure 8).
OIL TEMPERATURE CONTROL - Oil temperature will gen
erally run about 15  35°F above condensing tempera ture.
In many cases, an oil temperature control is not required if
condensing temperature is above 65°F as oil tempera ture can
be allowed to oat with condenser temperature.
Condensing Temperature: 65°F - 105°F
Oil Temperature: 80°F - 140°F
INSTALLATION  The thermosyphon oil cooler with oilside
piping and a thermostatically controlled mixing valve are fac
tory mount ed and piped. The customer may need to supply
and generally install all piping and equip ment (depending
on the scope of the equipment supplied) located outside
of the shaded area on the piping diagram (Figure 10) with
consideration given to the following:
1. The refrigerant source, thermosyphon or system receiv er,
should be in close proximity to the unit to minimize piping
pressure drop.
2. The liquid level in the refrigerant source must be 6 to 8
feet minimum above the center of the oil cooler.
3. A safety valve should be installed if refrigerant isolation
valves are used for the oil cooler. A refrigerantside safety
valve is required in this location only when refrigerant iso
lation valves are installed between the cooler and thermo
syphon receiver. If no valves are used between the cooler
and TSOC receiver, the safety valve on the TSOC receiver
must be sized to handle the volume of both vessels. Then,
the safety valve on the cooler vent (liquid refrigerant side)
can be eliminated.
4. The system receiver must be below the thermosyphon
receiver in this arrangement.
NOTICE
The component and piping arrangement shown in Figure
10 is intended only to illustrate the operating principles
of thermosyphon oil cooling. Other component layouts
may be better suited to a specic installation. Refer to
publication 070.900-E for additional information on Ther-
mosyphon Oil Cooling.

Johnson Controls Frick 852 Specifications

General

Brand	Johnson Controls
Model	Frick 852
Category	Compressor
Language	English