13
07.03
The CA-dryer includes a refrigerant system cooling the
compressed air flow. The steam saturation limit is low-
ered causing condensate to fall out, which is removed by
the condensate drain.
The higher the cooling temperature difference of the air,
the higher is the amount of condensate.
The lower the cooling temperature of air, the lower is the
moisture content.
The lower limit of air cooling results from the operating
principle of the CA-dryer based on the moisture separa-
tion in liquid form. Thus, the freezing point of water, i.e. a
temperature of 35 °F, is the lower limit. For reliability rea-
sons, a practical setting is used, which lies above this
theoretical limit of 35 °F.
The compressed air precooled in the aftercooler and
saturated with moisture enters into the CA-dryer and is
precooled in the first cooling stage, the air-to-air heat
exchanger without additional energy. Cooling is carried
out in counterflow to the already cooled air heated dur-
ing this process.
The cooling to the pressure dew point is performed in the
second cooling stage, the refrigerant-to-air heat ex-
changer cooled by the refrigerant system installed. Sub-
sequently, the cooled compressed air is reheated in the
air-to-air heat exchanger as already described.
The pressure dew point temperature is indicated on the
switch cabinet (fig. 5/5).
The refrigerant is injected into the refrigerant-to-air heat
exchanger where it evaporates, thereby cooling the com-
pressed air. A capacity control system at the refrigerant
side controls the capacity required by the compressed
air to ensure a constant pressure dew point temperature
in all capacity ranges.
The refrigerant compressed by the motor compressor is
condensed within the condenser and is available for the
evaporation again.
The CA-dryer can be operated under partial load, caused
by lower compressed air throughout or lower compressed
air inlet temperature, within the range of 0 to 100% ca-
pacity in continuous operation.
3.5
Principle of opera-
tion
3.6
Mode of operation
3.6.1
Compressed air side
3.6.2
Refrigerant side
3.6.3
Pressure dew point
control
Part 3
Description
