19
OPERATIONAL OVERVIEW
Air-Cooled Condensing Unit
The air-cooled condenser on the purge unit provides the necessary cooling source to
condense and separate refrigerant from non -condensables in the purge tank. The unit
operates most efficiently within an ambient temperature range of 40° to 120°F. The rate at
which the purge removes air from the chiller is proportionate to the ambient temperature. The
higher the ambient temperature the slower the purge rate. Conversely, purge efficiency is
proportionate to chiller saturated condensing temperature. The higher t he chiller saturated
condensing temperature the greater the purge efficiency.
NOTE:
Because the purge utilizes its own self-contained cooling source, it is capable of
operating whether the chiller is running or not. No water connections are required.
Operating cycle
Refrigerant vapor from the chiller condenser passes through a 1/2 -inch line, then through an
inlet filter-drier into the top of the purge tank. The purge tank is cooled by the purge’s air
cooled condensing unit. As the chiller’s refrigerant condenses the pressure in the purge tank
lowers, drawing in additional vapor along with any air and moisture that may be present from
the chiller’s condenser (see Figure 6 below and flow schematic Figure 5 on page 18).
Under conditions of no air present in the system, the purge condensing unit compressor
suction temperature will be at 22°F or above. As air accumulates within the purge tank the
available condensing surface area of the condensing coil decreases, causing the condensing
unit compressor suction temperature to drop due to decreasing load. When the suction
temperature (Superheat) drops to 18°F indicating the presence of air, Temperature Sensor
TS1 initiates a pumpout cycle. The air in the purge tank is then vented by the pumpout
compressor. As air is removed from the chiller system to the point where only refrigerant
vapor is drawn into the purge tank, the purge condensing unit compressor suction
temperature will rise above 22°F, at which point Temperature Sensor TS1 terminates the
pumpout cycle. The pumpout cycle is typically 30 to 90 seconds.
Figure 6. -
Refrigerant Circuit
Schematic
Содержание Redi-Purge PRG-113-C3
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