8
Fig. 4 — Typical 19MV Liquid Level Assembly Detail
REFRIGERATION CYCLE
The compressor continuously draws refrigerant vapor from the
evaporator at a rate set by the amount of first stage guide vane
opening and motor speed. As the compressor suction reduces the
pressure in the evaporator, the remaining refrigerant boils at a fair-
ly low temperature (typically 38 to 42°F [3 to 6°C]). The energy
required for boiling is obtained from the water flowing through the
evaporator tubes. With heat energy removed, the water becomes
cold enough to use in an air-conditioning circuit or process liquid
cooling.
After taking heat from the water, the refrigerant vapor is com-
pressed by a back-to-back compression connected by means of in-
terstage piping. Compression adds heat energy and the refrigerant
is quite warm (typically 98 to 102°F [37 to 40°C]) when it is dis-
charged from the compressor into the condenser.
Relatively cool (typically 65 to 90°F [18 to 32°C]) water flowing
into the condenser tubes removes heat from the refrigerant, and
the vapor condenses to liquid. The liquid drains from the bottom
of the condenser and, for units equipped with economizer option,
flows into the high pressure side of the BPHX.
At the outlet of the high pressure side of the BPHX a small portion
of refrigerant is separated from the main stream, brought to a low-
er pressure by an EXV, and fed back through the low pressure side
of the BPHX. As the two streams of refrigerant flow through the
BPHX heat transfered from the main stream of refrigerant vapor-
izes the economizer stream. This vapor flows to the second stage
of the compressor for greater cycle efficiency. The amount of va-
por introduced to the second stage is determined by an EXV
which meters the flow of vapor to maintain a specified vapor su-
perheat.The cooled liquid flows out of the economizer and into the
expansion control system and at this point the cycle is the same
with or without the optional economizer. The expansion control
system will meter the refrigerant follow into the evaporator for
best system performance. See Fig. 5-6 for the refrigeration cycle
diagram for economized and non-economized systems.
ISOLATION
VALVES
CONDENSER
LIQUID LEVEL
SENSOR HOUSING
Summary of Contents for AquaEdge 19MV
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