Structure Of Two Stage Centrifugal Chiller; Cycle Of The Chiller - LG RCWFH Series Instruction Manual

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3. STRUCTURE OF TWO STAGE CENTRIFUGAL
CHILLER

3-1. Cycle of the chiller

The two Stage Centrifugal chiller uses environment friendly high pressure refrigerant R-134a.
- In this cycle, as shown in the following figure, the vaporized low temperature and low pressure refrigerant gas
passes the Inlet Guide Vane, and enters the 1st impeller of the compressor.
Since the inlet gas amount is dependent on the guide vane's opening, the chiller capacity can be controlled.
- Refrigerant gas that entered the 1st impeller is compressed to a mid-temperature and mid pressure, passes
through the return channel, cooled by low temperature gas from the economizer, and then enters the 2nd impeller.
- The refrigerant gas entered the 2nd impeller is compressed as high-temperature and high-pressured refrigerant
gas, and discharged to the condenser. The gas loses its heat via cooling water in the heat transfer tubes and even-
tually condensed to liquid.
- The condensed refrigerant liquid passed the 1st orifice, becomes mixed state and enters the lower part of the
economizer which divides into gas and liquid of refrigerant. The gas part is mixed with the mid temperature and
mid pressured gas which was compressed in the 1st impeller, and then enters the 2nd impeller. The liquid part of
the refrigerant enters the lower part of evaporator via 2nd orifice.
- The liquid refrigerant entered into the evaporator, is then spread into wider surface of evaporator by distributor. Fi-
nally the distributed refrigerant evaporates by taking the heat from the chilled water inside the evaporator tubes
and repeats the cycle.
- Some part of the over-cooled refrigerant liquid in the condenser, flows through the valve, filter, moisture indicator,
and enters into the motor and oil cooling system individually.
- The refrigerant liquid flew into the motor is being sprayed so that it can cool the motor's coil and is returned to the
evaporator.
- The refrigerant flew into the oil cooling system, flows through the disc-shaped oil cooler. Refrigerant that left the
oil cooler is then returned to evaporator.
Chilled water inlet
Chilled water outlet
2nd Compressor
1st orifice
2nd orifice
Fig 4. Two stage centrifugal chiller
2nd Impeller
1st Impeller
I.G.V
Condenser
Evaporator
Refrigerant liquid
Refrigerant gas
Cooling water outlet
Cooling water inlet