Filter
Top Products
10 TRG-TRC010-EN
notes
period one
Components
Liquid refrigerant from the condenser enters the first expansion device, which
reduces the pressure of the refrigerant to that of the second-stage impeller
inlet. This pressure drop causes a portion of the liquid refrigerant to evaporate,
or flash, and the resulting mixture of liquid and vapor enters the economizer
chamber. Here, the vapor is separated from the mixture and is routed directly to
the inlet of the second stage impeller. The remaining liquid travels on to the
second expansion device and evaporator.
Just before entering the evaporator, the liquid refrigerant flows through a
second expansion device that reduces its pressure and temperature to
evaporator conditions.
Flashing a portion of the refrigerant prior to the economizer reduces the
amount of compressor power required, since the refrigerant vapor generated in
the economizer only needs to be compressed by the second-stage impeller.
The benefit of the economizer will be discussed in greater detail in Period 2.
In a chiller with a 3-stage compressor, the expansion process can be separated
into 3 steps with separate economizer chambers between the steps.
Liquid refrigerant from the condenser enters the first orifice (expansion device),
which reduces the pressure of the refrigerant to that of the third-stage impeller
inlet. This pressure drop causes a portion of the liquid refrigerant to flash, and
the resulting mixture of liquid and vapor enters the high-pressure chamber of
the economizer. Here, the vapor is separated from the mixture and is then
routed directly to the inlet of the third-stage impeller. The remaining liquid
travels on to the second expansion device.
The second expansion device further reduces the pressure of the refrigerant to
that of the second-stage impeller inlet. This pressure drop causes a portion of
the liquid refrigerant to flash, and the resulting mixture of liquid and vapor
enters the low-pressure chamber of the economizer. Here, the vapor is
separated from the mixture and routed directly to the inlet of the second-stage
impeller. The remaining liquid travels on to the third expansion device and
evaporator.
3-stage chiller
Economizer
liquid refrigerant
liquid refrigerant
to evaporator
to evaporator
orifice
orifice
orifice
orifice
refrigerant vapor
refrigerant vapor
to second stage
to second stage
of compression
of compression
refrigerant vapor
refrigerant vapor
to third stage
to third stage
of compression
of compression
liquid refrigerant
liquid refrigerant
from condenser
from condenser
Figure 16
trgtrc010_book.book Page 10 Wednesday, September 1, 1999 10:39 AM