intarblock | intartop
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3. OPERATION
INTARBLOCK and INTARTOP are refrigeration machines operating under a vapour compression
cycle.
Refrigeration cycle
The refrigeration cycle uses a phase change refrigerant fluid in a closed circuit, with the following four
steps:
Expansion: refrigerant expansion takes place in the capillary tube between high and low pressure
sections. During the expansion, liquid refrigerant cools down to the evaporating temperature.
Evaporation: In the evaporator the refrigerant evaporates under constant temperature and pressure
absorbing heat from the cold room. Once the refrigerant vapour has been fully evaporated, it is slightly
overheated beyond the evaporation temperature.
Compression: The resultant refrigerant vapour is suctioned from the evaporator by the compressor
through the suction line. The compressor compresses the refrigerant vapour up to high pressure and
temperature.
Condensation: the hot high pressure gas is desuperheated and condensed, at a constant pressure
and temperature, in the el condenser by exhausting the latent evaporation to the outer ambient. Once
the refrigerant has been fully condensed, the liquid refrigerant is overcooled beyond the condensing
temperature.
High pressure liquid refrigerant is then driven to the capillary tube, and therefore closing the circuit.
Defrost cycle
Because of the evaporator temperature can be below 0ºC (32ºF), frost is likely to deposit on the
evaporator surface through the condensation of the water vapour contained in the air. To prevent the
air flow from being obstructed with the consequently loss of performance, the instrument switches
automatically to the defrost operation mode every given period of time.
During the defrost cycle, by opening the solenoid valve, part of the hot gas from the compressor
discharge is injected into the evaporator. The evaporator temperature is rapidly increased in order to
melt the frost on it while the inside fan is off.
The defrost water is collected in the drain tray and conducted to the drain bucket. This drain bucket
contains a hot gas coil to progressively evaporate the drain water to the outer ambient.
