RTAG adopt EXV to control refrigerant
fl
ow. As refrig-
erant passes through the valve the pressure is dropped
substantially, which results in vaporization of some of
the refrigerant. So two phase refrigerant enter the dis-
tribution of evaporator (state 4), then spray on tube of
evaporator evenly.
A TXV ( Thermal Expansion Valve) is applied in oil cooler
circuits.
To enhance the performance of the heat exchanger
surfaces an oil separator is placed in the discharge line
between the compressor and the condenser. RTAG
oil separator is centrifuge type. The refrigerant gas is
discharged by the compressor, entering oil separator
cylinder from the tangential direction of the upper part
of it. Oil drop will be thrown out from the refrigerant gas
due to the centrifugal force produced by the rotating in
the cylinder. Oil that is removed from the refrigerant falls
along the cylinder wall by gravity into the oil sump, and
then returned to the compressor. The refrigerant vapor,
get rid of the oil, is discharged from the top of the oil
separator,
fl
ow into the condenser. Approximately 99.5%
of the oil is removed from the refrigerant in the separa-
tor.
See
Figure 59
System Schematic. Screw compressors
require large quantities of oil for lubricating and sealing
the rotors and lubricating the bearings, pushing slide
valve. The oil mixed with refrigerant at the discharge
of the compressor, majority of it is separated and
fl
ow
to bottom of oil separator, minority enters system cir-
cuits with refrigerant. Oil in the oil sump of separator
is discharge from oil separator by high pressure when
compressor is working. It
fl
ows through oil cooler, angle
valve, compressor inner
fi
lter and shut off valve, then
is divided into two ways: one injects to rotors from the
top shell of compressor, to lubricate rotors, and seal the
gaps between rotors and compressor shell. Another way
inject to the bearing chamber to lubricate bearing, then
go back to suction port of rotor through oil circuits in
the compressor shell. Once oil is injected into the com-
pressor rotors it mixes with the refrigerant again and is
delivered back to the oil separator. Very little amount of
oil pasts the oil separator, and
fl
ows through the con-
denser, subcooler and expansion valve into the evapora-
tor. This part of oil is collected with refrigerant at rich oil
range of CHIL evaporator, is returned through a line that
is connected to the compressor.
An internal, pilot operated shutoff valve is provided to
prevent oil
fl
ow into the compressor when the compres-
sor is not running.
Operating Principles
RTAG-SVX001H-EN
99
per tubes, mechanically expanded into the tube sheets.
Tubes are cleanable with dismountable water boxes.
Tubes exterior diameter is 19mm. The evaporator is
designed, tested and stamped in accordance with
ASME Pressure regulation for a refrigerant side
working pressure of 1.38MPa. Water side working
pressure has one kind: 1.03MPa (150psig). Standard
water connections are Flange.
