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9.4 Refrigerating compressor
The refrigerating compressor is the pump in the system, gas coming from the evaporator (low pressure side) is compressed up to the
condensation pressure (high pressure side). The compressors utilized are manufactured by leading manufacturers and are designed for
applications where high compression ratios and wide temperature changes are present.
The hermetically sealed construction is perfectly gas tight, ensuring high-energy efficiency and long, useful life. Dumping springs support
the pumping unit in order to reduce the acoustic emission and the vibration diffusion. The aspirated refrigerant gas, flowing through the coils
before reaching the compression cylinders cools the electric motor. The thermal protection protects the compressor from over heating and
over currents. The protection is automatically restored as soon as the nominal temperature conditions are reached.
9.5 Condenser
The condenser is the component in which the gas coming from the compressor is cooled down and condensed becoming a liquid. Mecha-
nically, a serpentine copper tubing circuit (with the gas flowing inside) is encapsulated in an aluminum fin package.
The cooling operation occurs via a high efficiency fan, creating airflow within the dryer, moving air through the fin package. It's mandatory
that the ambient air temperature does not exceed the nominal values. It is also important to keep the condenser unit free from dust and other
impurities
9.6 Filter dryer
Traces of humidity and slag can accumulate inside the refrigerant circuit. Long periods of use can also produce sludge. This can limit the
lubrication efficiency of the compressor and clog the expansion valve or capillary tube. The function of the filter drier, located before the
capillary tubing, is to eliminate any impurities from circulating through the system.
9.7 Capillary tube
It consists of a piece of reduced cross section copper tubing located between the condenser and the evaporator, acting as a metering device
to reduce the pressure of the refrigerant. Reduction of pressure is a design function to achieve optimum temperature reached within the
evaporator: the smaller the capillary tube outlet pressure, the lower the evaporation temperature.
The length and interior diameter of the capillary tubing is accurately sized to establish the performance of the dryer; no maintenance or
adjustment is necessary.
9.8 Alu-Dry module
The heat exchanger module houses the air-to-air, the air-to-refrigerant heat exchangers and the demister type condensate separator. The
counter flow of compressed air in the air-to-air heat exchanger ensures maximum heat transfer. The generous cross section of flow channel
within the heat exchanger module leads to low velocities and reduced power requirements. The generous dimensions of the air-to-refrige-
rant heat exchanger plus the counter flow gas flow allows full and complete evaporation of the refrigerant (preventing liquid return to the
compressor). The high efficiency condensate separator is located within the heat exchanger module. No maintenance is required and the
coalescing effect results in a high degree of moisture separation.
9.9 Hot gas by-pass valve
This valve injects part of the hot gas (taken from the discharge side of the compressor) in the pipe between
the evaporator and the suction side of the compressor, keeping the evaporation temperature/pressure cons-
tant at approx. +36°F (+2°C). This injection prevents the formation of ice inside the dryer evaporator at every
load condition.
Adjustment
The hot gas by-pass valve is adjusted during the manufacturing testing phase. As a rule no adjustment is
required; anyway if it is necessary the operation must be carried out by an experienced refrigerating engineer.
ATTENTION
Without compressed air flow through the dryer, rotate the adjusting screw (position A on the drawing) until the following value is reached:
Hot gas setting :
R134.a pressure 29.0 psig (+ 1.45 / -0 psi) [2.0 barg (+0.1 / -0 bar)]
R407C pressure 65.3 psig (+1.45 / -0 psi) [4.5 barg (+0.1 / -0 bar)]
the use of ¼" Schrader service valves must be justified by a real malfunction of the refrigerating system.
Each time a pressure gauge is connected, a part of refrigerant is exhausted.
63
A
4 mm
5/32 in.
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+
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