Whirlpool ATE0743SPP Technical Manual page 22

The refrigerant leaves the condenser coil as a
warm high pressure liquid. It then passes
through the filter/drier (if so equipped). It is the
function of the filter/drier to trap any moisture,
contaminants, and large particulate matter
present in the sealed system.
The liquid refrigerant next enters a metering
device called a "capillary tube" whose purpose
is to "meter" (control or measure) the quantity
of refrigerant entering the evaporator coil.
In the capillary tube, this is accomplished
through its size and length, and the pressure
difference present across the device.
Since the evaporator coil is under a lower
pressure than the liquid line, (due to the suction
created by the compressor), the liquid refriger-
ant leaves the capillary tube, and enters the
evaporator coil.
As the liquid enters the evaporator coil, the
larger area and lower pressure allows the
refrigerant to expand, and lower its tempera-
ture. This expansion is often referred to as
"boiling."
Suction Line
Evaporator Coil
Capillary Tube
(Metering)
Refrigerant
Strainer
Since the blower is moving indoor air across
the finned surface of the evaporator coil, the
expanding refrigerant absorbs some of the
heat. This results in a lowering of the indoor air
temperature, hence the "cooling" effect.
The expansion and absorption of heat causes
the liquid refrigerant to evaporate, and change
back to a gas. Once the refrigerant has been
evaporated, it is further heated by the air that
continues to flow across the evaporator coil.
The particular system design determines at
exactly what point the change of state, from a
liquid to a gas, takes place in the evaporator. In
all cases, however, the refrigerant must be
totally evaporated (changed to a gas) before
leaving the evaporator coil.
The low pressure (suction) created by the
compressor causes the refrigerant to leave the
evaporator through the suction line as a cool,
low pressure vapor. The refrigerant then re-
turns to the compressor, where the cycle is
repeated.
Discharge Line
Condenser Coil
Compressor
Filter/Drier
3-2
Liquid Line