Principle Of Operations; Freezing Cycle; Harvest Cycle - Scotsman ACM 25 Service Manual

Page 10
PRINCIPLE OF OPERATION
In the Scotsman ACM 25, the water to make ice
is continually moved or circulated by a small
electric pump that sprays the water under gentle
pressure through the two spray jets into the eight
inverted cube molds.
Part of the water that hits the cold refrigerated
molds freezes, building gradually into full ice
cubes bell shaped.
FREEZING CYCLE (How it works)
The hot gas refrigerant, pumped and discharged
by the compressor, passes through the condenser
where the fan blowing air causes the changing of
it into liquid.
The liquid line takes the refrigerant from the
condenser to the capillary tube. During the travel
into the capillary tube, the liquid refrigerant looses
gradually its temperature and pressure, then it
reaches the evaporator coils.
Because of the water sprayed against the
evaporator molds and coil, the liquid refrigerant
senses the heat of this water and starts boiling,
changing, as a consequence, from liquid into
vapor state.
The vapor refrigerant is sucked back to the
compressor through the suction line.
The freezing cycle is controlled by a temperature
control which determines as well the length of the
cycle and consequently the size of the ice cube.
During this phase, the contact point of the tempe-
rature control maintains closed the circuit of the
water pump which constantly sprays the water
under the evaporator mold cups up to the point
that the ice cubes reach their full size.
HARVEST CYCLE (How it works)
As soon as the temperature control senses the
temperature in the evaporator corresponding to
the full size cubes, the contact moves to close the
circuit of the Hot Gas Valve Coil and consequently
to open the circuit of the water pump which
momentarily stops.
The hot gas refrigerant discharged by the
compressor is now diverted through the opened
hot gas valve to the evaporator coil.
The hot gas circulares through the evaporator
coil raising the temperature around the cube
cups sufficiently to release the ice cubes.
The released ice cubes drop by gravity into the
storage bin.
The temperature control bulb, due to the warm
temperature in the evaporator moves again the
contact de-energizing the hot gas valve and
energizing the water circulating pump starting a
new freezing cycle.
WATER CIRCUIT
∑
π

FREEZING CYCLE

∑
∏
π
∫

HARVEST CYCLE

∑
∏
π
∫
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∂
∏
EVAPORATOR
∫
≠
BIN
SPRAY TUBE
WATER PUMP
∞
WATER RESERVOIR
∂
EVAPORATOR
≠
ACCUMULATOR
CAPILLARY TUBE
SUCTION LINE
∞
COMPRESSOR
±
HOT GAS SOLENOID
±
VALVE CLOSED
≤
CONDENSER
≥
FAN MOTOR
DRIER
Ω
∂
EVAPORATOR
≠
ACCUMULATOR
CAPILLARY TUBE
SUCTION LINE
∞
COMPRESSOR
±
HOT GAS SOLENOID
±
VALVE OPENED
≤
CONDENSER
≥
FAN MOTOR
DRIER
Ω