4
YORK INTERNATIONAL
SECTION 1
DESCRIPTION OF SYSTEM AND FUNDAMENTALS OF OPERATION
FIG. 1
MODEL YK MILLENNIUM CHILLER
SYSTEM OPERATION DESCRIPTION (See Fig. 2)
The YORK Model YK Millennium Chiller is commonly
applied to large air conditioning systems, but may be
used on other applications. The chiller consists of an
open motor mounted to a compressor (with integral
speed increasing gears) condenser, cooler and vari-
able flow control.
The chiller is controlled by a modern state of the art
MicroComputer Control Center that monitors its opera-
tion. The Control Center is programmed by the opera-
tor to suit job specifications. Automatic timed start-ups
and shutdowns are also programmable to suit night-
time, weekends, and holidays. The operating status,
temperatures, pressures, and other information perti-
nent to operation of the chiller are automatically dis-
played and read on a 40 character alphanumeric mes-
sage display. Other displays can be observed by press-
ing the keys as labeled on the Control Center. The chiller
with the MicroComputer Control Center is applied with
an electro-mechanical starter, YORK Solid State Starter
(optional), or Variable Speed Drive (optional).
In operation, a liquid (water or brine to be chilled) flows
through the cooler, where boiling refrigerant absorbs
heat from the liquid. The chilled liquid is then piped to
fan coil units or other air conditioning terminal units,
where it flows through finned coils, absorbing heat from
the air. The warmed liquid is then returned to the chiller
to complete the chilled liquid circuit.
The refrigerant vapor, which is produced by the boiling
action in the cooler, flows to the compressor where the
rotating impeller increases its pressure and tempera-
ture and discharges it into the condenser. Water flow-
ing through the condenser tubes absorbs heat from
the refrigerant vapor, causing it to condense. The con-
denser water is supplied to the chiller from an external
source, usually a cooling tower. The condensed refrig-
erant drains from the condenser into the liquid return
line, where the variable orifice meters the flow of liquid
refrigerant to the cooler to complete the refrigerant
circuit.
The major components of a chiller are selected to
handle the refrigerant, which would be evaporated at
28815A
CONTROL
CENTER
COMPRESSOR
COOLER
CONDENSER
MOTOR
