Dryer System - Hitachi HISCREW 2000 Series Instruction Manual

6.3 Dryer System

：Air flow
：Ventilation
：Refrigerant flow
Refrigerant pressure gauge
(low-pressure side)
P
Capillary tube
H
6.3.1 Compressed Air Flow
Compressed air precooled by the aftercooler is
heat-exchanged with low-temperature com-
pressed air by the precooler A of heat exchanger,
and then with refrigerant by the air cooler B. At
this time, the steam contained in the compressed
air is condensed and automatically discharged as
drain from the auto drain trap C. The cooled
compressed air is returned to the precooler A,
heat-exchanged with compressed air cooled by
the aftercooler, and then discharged.
6. SYSTEM OF EACH COMPONENT [Dryer System]
Precooler A
Auto drain trap C
Hot gas bypass valve G
Condenser E
Fan
F
Compressed air inlet
Air cooler B
Accumulator I
Refrigerating
compressor
D
6.3.2 Refrigerant Flow
The high-temperature and high-pressure refrig-
erant gas discharged from the refrigerating com-
pressor D gets into the condenser E. It is
cooled by the fan F and turns into high-pressure
liquid refrigerant.
The high-pressure refrigerant is squeezed by the
capillary tube H and sent to the air cooler B as a
low-pressure liquid refrigerant. The refrigerant
is heat-exchanged with compressed air and
evaporated. It is sucked as overheated steam into
the refrigerating compressor D, recompressed
and then discharged. This cycle is repeated.
The hot gas bypass valve G works automatically
depending on a load and an ambient temperature,
and controls the evaporation temperature of re-
frigerant to be kept constant in order to prevent
condensed water from freezing by overcooling at a
low temperature and at no load.
Compressed air
outlet
Heat exchanger
PS
High-pressure switch
1
PS
2
Fan control
switch
33