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C. Lower Section
The lower section houses the high side refrigeration and hydraulic
systems. It includes a compressor, water-cooled
condenser/receiver (5549 models), water-cooled condenser and
separate receiver (on 6049 models), liquid sub-cooled heat
exchanger, high side oil separator, low side oil separator, surge
drum, liquid injector/distributor, oil float valve, hydraulic pump, and
other accessories.
D. Refrigeration Cycle
Refrigerants offered in the Freze -Cel are R-502, R-404A and R-
507. The refrigeration cycle is as follows: (Refer to Dole Drawing
7511-B100).
The high-pressure liquid stored in the condenser flows through the
filter/dryer, through the sub-cooling shell and tube heat exchanger,
to the bottom of the injector distributor. In the injector, the
refrigerant achieves a high velocity, which reduces its pressure and
causes it to leave the nozzle in the jet stream. It enters the mixing
throat of the injector and mixes with cold liquid refrigerant from the
surge drum. The resulting sub cooled liquid is routed through the
distributor to each freezer plate. A portion of the liquid vaporizes in
the plates as a result of absorbing heat from the product.
The compressor draws its suction from the top of the surge drum;
liquid refrigerant in the drum is drawn into the injector where it
mixes with the warmer liquid. The compressor discharge is routed
through an oil separator to a water-cooled condenser (on Model
6049) or a condenser/receiver (on Model 5549).
E. Oil Return Systems
a. Low Side Oil Return:
Oil that makes its way into the surge drum exits the bottom
of the drum and travels through the oil return solenoid valve
(SV2), a pre-set hand expansion valve (HEV), a sight glass
(SG2), and into the compressor suction line at the
compressor. The oil return solenoid valve is a normally
closed valve that is energized (opened) whenever the
compressor is running and is de-energized (closed)
whenever the compressor is not running.
b. High Side Oil Return:
A shell and tube oil separator is provided in the compressor
discharge line to keep oil passing into the freezer plates to a
minimum. Oil separated from the discharge gas is returned
to the compressor crankcase via a float valve.
