Flexzilla Pro Energy Ecient Refrigerated Air Dryers
5
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injected in the evaporator (heat exchanger) by an
expansion valve. This expansion valve is protected
by a lter, which removes parcles and humidity
that could be in the circuit.
D) The injected liquid lls in the refrigerant secon of
the air/refrigerant heat exchanger and evaporates
by taking out the humidity from the compressed
air. The gaseous refrigerant is sucked in the
compressor and the cycle carries on.
E) In order to keep the evaporaon pressure
steady, and the refrigerant temperature in the
heat exchanger, a by-pass valve is injecng hot
gaseous refrigerant in the circuit. On certain dryers,
an automac expansion valve regulates the
amount of refrigerant.
3) Compressed air circuit
A) The saturated hot compressed air ows into the
economizer where it is pre-cooled by the out
owing dry chilled air. In the cold operang
condions the air refrigerant secon connues
to cool down to dew point and enters the
separator where condensates are collected.
The outgoing chilled air is then warmed up in the
economizer by the hot incoming air. This eliminates
condensaon on dryer outlet air piping.
B) The condensates are collected aer centrifugal
separaon and drained out through the
automac trap.
C) As long as the compressed air temperature
does not drop below dew point, there will be no
condensaon in the air circuit.
Compressed Air Dryer Working Principle
4) Refrigerant compressor
Increases the pressure of temperature of refrigerant.
There are two types of compressors commonly used
according to refrigerant capacity on this applicaon:
- Piston type
- Scroll type
5) Condenser
Dissipates the heat provided by evaporator and
compressor. there are two types of condensers used
on the applicaon:
- Air Cooled Type (standard)
These condensers are designed to dissipate the heat
to the ambient air. The fans are used to force the air
ow through the cooling ns to enhance the heat
transfer.
- Water Cooled Type (oponal)
These condensers are designed to dissipate the heat
to a water ow. A shell and tube heat exchanger is
used for this purpose.
6) Refrigerant circuit protecon
A) Overload: The single phase refrigerant compressors
are equipped with an overload switch in case of
malfuncon, if overload switches automacally.
B) High Pressure Safety Overload Switch: Refrigerant
line is considered a pressure vessel. That is why it
is protected against bursts by the help of manually
reseng the switch. It is set to 362 psi for dryers
working with R134a refrigerant.
C) Filter dryer: A refrigerant circuit is a close circuit
and total water removal in the refrigerant circuit is
necessary in order to obtain correct operaon.
D) To avoid problems, the refrigerant circuit must be
vacuumed before loading the refrigerant.
E) Water-cooled dryers have a safety high-pressure
switch. In case of cooling water failure, the safety
switch stops the dryer. When the safety switch has
tripped out, it has to be manually reseled before
switching on the dryer.
7) Refrigerant circuit controls
A) Liquid refrigerant injecon: the liquid refrigerant
is released into the evaporator by a control valve.
This is a thermostac valve for maintaining a
constant overheang of the refrigerant in the
evaporator(s).
B) Constant evaporang pressure: In the dryers
equipped with a by-pass valve, the evaporang
pressure is kept constant by a controlled injecon
of hot gas from the high-pressure side into the low-
pressure secon of the circuit.
Compressed Dry
Air Outlet
Compressed
Wet Air Inlet
Refrigerant Gas High Pressure Line
Refrigerant Gas Low Pressure Line
A - Refrigerant Compressor
B - Condenser
C - Filter Dryer
D - Expansion Valve
E - Heat Exchanger
F - Hot Gas Bypass Valve
G - Drain
