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TRG-TRC010-EN 11
period one
Components
notes
Again, the final expansion device reduces the pressure and temperature of the
refrigerant to evaporator conditions.
Evaporator
In the flooded shell-and-tube evaporator shown, the low-pressure mixture
of liquid refrigerant and refrigerant vapor enters the distribution system that
runs the entire length of the shell. Small openings and baffles in the passage of
the liquid distributor provide an even spray of refrigerant over the surfaces of
the tubes inside the evaporator shell, where the refrigerant absorbs heat from
relatively warm water flowing through the tube bundle. This transfer of heat
boils the liquid refrigerant on the tube surfaces. The resulting vapor passes
through an eliminator that prevents liquid from being drawn upward. The vapor
collects in a large chamber at the top of the shell and is drawn back to the
compressor. The now-cool water can be used in a variety of comfort or process
applications.
Some chiller designs may make use of a direct expansion (DX) shell-and-
tube evaporator. In this type of evaporator, liquid refrigerant flows through
the tubes and water fills the surrounding shell. As heat is transferred from the
water to the refrigerant, the refrigerant boils inside the tubes and the resulting
vapor is drawn to the compressor.
Evaporator
eliminator
eliminator
liquid
liquid
distributor
distributor
orifice system
orifice system
liquid
liquid
refrigerant
refrigerant
tube bundle
tube bundle
chilled
chilled
water
water
return
return
Figure 17
trgtrc010_book.book Page 11 Wednesday, September 1, 1999 10:39 AM