Icematic M302 - 4. Operation Modes; 4.1 Refrigeration During Freeze

English
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SERVICE MODULARI06/2014
4. OPERATION
4.1 REFRIGERATION DURING FREEZE
• This ice machine employes either air or water as a condens
ing media, the refrigeration system for either one is a follows:
At the hermetic compressor, Refrigerant is compressed into
a high temperature, high pressure gas.
The gas moves through the discharge line into the con
denser, air or watercooled. If aircooled, the discharge pres
sure will change with the heat load and the ambient air
temperature.
• If watercooled, the discharge pressure is controlled by the
amount of water flowing through the condenser  which is
determined by the water regulating valve.
After the gas is cooled in the condenser, giving up much of
its heat, the gas condenses into a high pressure liquid. This
liquid travels through the liquid line to the metering device,
a thermostatic expansion valve.
The thermostatic expansion valve meters how much liquid
refrigerant is to be allowed into the evaporator section of the
refrigeration system.
This is determined by the temperature of the TXV sensing
bulb, located on the suction line manifold, at the outlet of
the evaporator.
• If the bulb senses a warm suction line, more refrigerant is al
lowed into the evaporator, common at the beginning of the
freeze cycle and when the temperature begins to fall, less
refrigerant is allowed through.
This is why the suction side gauge pressure will decline
throughout the freeze cycle. At the evaporator, the liquid re
frigerant released from high pressure, boils off in the low
pressure environment and absorbs heat, thus cooling the
evaporator surface and anything near it, such as water.
• The low pressure refrigerant vapor then is forced through the
heat exchanger where any excess liquid refrigerant boilsoff,
allowing only refrigerant vapor to enter the compressor suc
tion tube, where it is recompressed into high pressure, high
temperature gas again and the cycle repeats.
HE AT
EX CHANG ER
EV APO RATOR
COND ENS ER
CO MPR ESSOR
EX PANSI ON VALVE
HO T GAS SOLE NOID VA LVE
AI R OR WA TER
DR IER
S
TR AINER
RE CEIVE R
(W ATER COO LE D ONL Y)
LO W PRE SS URE V AP ORLO W PRE SS URE L IQUIDHI GH PR ES SURE LIQ UIDHI GH PR ES SURE VA POR
X
FREEZE CYCLE
REFRIGERATION SYSTEM SCHEMATIC