TENNEY ENVIRONMENTAL
REFRIGERANT
FLOW
I
This description pertains to a small cascade system and can be followed with your
Refrigeration Drawing
R-1OXX4, or R-I IXX-4. There may be variations as noted elsewhere in
this manual. The high stage charge is noted on the serial tag. The low stage carries a static
pressure, noted on the serial tag, at room temperature.
10
cc of pentane is added to the low
stage charge to help prevent waxing of the lubricant at extremely low temperatures.
Flow of refrigerant
in
the high stage is from compressor C1 in the form of a hot gas, to the
chamber door mullion
heater(optional), and then to the air-cooled or water-cooled condenser.
As a liquid, the high stage refrigerant flows from the condenser to capillary tube dryer
assembly
D,
which meters refrigerant to the cascade condenser. After evaporating in the
condenser assembly, which is a heat-exchanger, the high stage refrigerant
returns to the
compressor
C1
through the suction line and accumulator SLA. The function of pressure switch
3PS is to energize the low stage compressor after the high stage has started. The purpose of
the arrangement is to prevent both compressors from hitting the power line at the same
instant.
Refrigerant flow in the low stage is from the compressor through the oil separator to the
cascade condenser where gaseous
very
high pressure refrigerant or low stage refrigerant is
cooled and liquefied. Capillary tube assembly
D
meters very high pressure refrigerant or low
stage refrigerant into the evaporatorwhich cools the chamber. From the evaporator,
refrigerant returns to the compressor through the suction line.
,-
Excess refrigerant is stored in the expansion tank and is fed back to the system on demand
.)
through
a
capillary tube.
Solenoid valve
14SOL serves two purposes: On a cooling "off' cycle, it functions as an artificial
loading valve, partially by-passing the evaporator and reducing cooling capacity. Refrigeration
is modulated through this valve, not by cycling of the compressors. Valve
14SOL also
functions as a
dumb valve. ~esponding to signals from pressures with 4PS, it is energized and
opens when head pressure exceeds a predetermined pressure setpoint, typically 280 PSIG.
.
.
14SOL will deenergize when head pressure falls back to 240
PSIG;
To Next Page
Loading...
