Description Of Operation - Gardner Denver RDS Series Operation And Maintenance

RDS Series — 50-1000 SCFM

Description of Operation

Operating principal - The dryers described in
this manual operate on the same principal. A
refrigeration unit reduces the temperature of a chamber
called an evaporator or heat exchanger through which
warm, moist, compressed air is passed. As the air is
passed through the chamber, it is cooled causing
moisture in the air to condense. The condensate is
collected and drained away via an automatic drain valve.
Air circuit - Warm, wet compressed air enters the dryer
and passes through the air to air heat exchanger. Here,
it is cooled by cool, dry air leaving the evaporator. The
pre-cooled air then enters the air to refrigerant heat
exchanger (evaporator ) where it is cooled to a temp
of approximately 33-35° F. Cooling in the evaporator
causes water vapor in the air to condense (removed
from the system by means of an automatic drain).
Figure 1.2 Refrigeration Circuit
A I
IR N
A O
IR UT
C
OMPRESSOR
H G
OT AS
V
ALVE
A A
IR TO IR
E
XCHANGER
- 3 -
Refrigerant circuit - Refrigerant (R-22) gas is pumped
at high pressure by a compressor to an air or water
cooled condenser where it is cooled and condensed
to a liquid form. The liquid is forced through a metering
device where the resulting pressure drop causes the
boiling point of the refrigerant to drop. Low pressure
liquid refrigerant enters the evaporator where heat from
the entering air is transferred causing it to boil and
become a low pressure, cool gas. A portion
of the liquid may be bypassed through a liquid injection
circuit that keeps the compressor cool under conditions
of high load and ambient temperatures. The low
pressure gas is returned to the compressor, where
it is re-compressed and begins the cycle again.
C
ONDENSER
H
EAT
E
XCHANGER
H
EAT
D
RAIN
Section 1
M
ETERING
D
EVICE