035-19569-101 (0109)
2-1
GB
2 PRODUCT DESCRIPTION
2.1 General (Figures 2.1 and 2.2)
The York YK Millennium™ Centrifugal Liquid Chiller is
primarily used for large air conditioning systems, but may
be used on other applications. The chiller is completely
factory-packaged including evaporator, condenser,
compressor, motor, lubrication system, graphic control
centre (OptiView), and all interconnecting unit piping
and wiring. The initial charge of refrigerant and oil is
supplied for each unit.
The chiller is controlled by a modern state of the art
microprocessor control centre that monitors its operation.
The control centre is programmed by the operator to suit
job specifi cations. Automatic timed start-ups and shut-
downs are also programmable to suit nighttime, week-
ends, and holidays. The operating status, temperatures,
pressures, and other information pertinent to operation
of the chiller are automatically displayed and read on
a graphic display. Other displays can be observed by
pressing the keys as labelled on the control centre.
The chiller with the graphic control centre (OptiView) is
compatible 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) fl ows
through the evaporator, 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 fl ows through fi nned coils, absorbing heat from the
air. The warmed liquid is then returned to the chiller to
complete the chilled liquid circuit.
The refrigerant vapour, which is produced by the boiling
action in the evaporator, flows to the compressor
where the rotating impeller increases its pressure and
temperature and discharges it into the condenser.
Water fl owing through the condenser tubes absorbs
heat from the refrigerant vapour, causing it to condense.
The condenser water is supplied to the chiller from an
external source, usually a cooling tower. The condensed
refrigerant drains from the condenser into the liquid
return line, where the variable orifi ce meters the fl ow
of liquid refrigerant to the evaporator to complete the
refrigerant circuit.
The major components of a chiller are selected to handle
the refrigerant, which would be evaporated at full load
design conditions. However, most systems will be called
upon to deliver full load capacity for only a relatively small
part of the time the unit is in operation.
Figure 2.1 YK Centrifugal Liquid Chiller (Front View)
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