Tubes; Evaporator; Condenser; Waterboxes - York YK Manual

Equipment Overview (Cont'd)
JOHNSON CONTROLS

Tubes

Heat exchanger tubes are state-of-the-art, high-efficiency, externally and internally en-
hanced type to provide optimum performance. Tubes in both the evaporator and con-
denser are 3/4" (19 mm) O.D. standard [or 1" (25.4 mm) optional in some shells] copper
alloy and utilize the "skip-fin" design, providing a smooth internal and external surface at
each intermediate tube support. This provides extra wall thickness (up to twice as thick)
and non work-hardened copper at the support location, extending the life of the heat ex-
changers. Each tube is roller expanded into the tube sheets providing a leak-proof seal,
and is individually replaceable.

Evaporator

The evaporator is a shell and tube type with customer process fluid flowing inside the
tubes and refrigerant removing heat on the shell side via evaporation. Evaporator codes
A_ thru Q_ utilize a hybrid falling film design. It contains a balance of flooded and falling
film technology to optimize efficiency, minimize refrigerant charge, and maintain reliable
control. A specifically designed spray distributor provides uniform distribution of refriger-
ant over the entire length to yield optimum heat transfer. The hybrid falling film evaporator
design has suction baffles around the sides and above the falling film section to prevent
liquid refrigerant carryover into the compressor.
Evaporator codes R_ thru Z_ are flooded type, with a liquid inlet distributor trough under-
neath the tube bundle. This provides uniform distribution of refrigerant over the entire shell
length to yield optimum heat transfer. Flooded evaporator designs have an aluminum
mesh eliminator on R_ thru Z_ shells located above the tube bundle to prevent liquid re-
frigerant carryover into the compressor.
A 1-1/2" (38 mm) liquid level sight glass is conveniently located on the side of the shell to
aid in determining proper refrigerant charge. The evaporator shell contains a dual refrig-
erant relief valve arrangement set at 180 psig (12.4 barg) on H and K compressor models;
235 psig (16.2 barg) on P and Q compressor models; or single-relief valve arrangement, if
the chiller is supplied with optional refrigerant isolation valves. A 1" (25.4 mm) refrigerant
charging valve is provided.

Condenser

The condenser is a shell and tube type, with a discharge gas baffle to prevent direct high
velocity impingement on the tubes. The baffle is also used to distribute the refrigerant gas
flow properly for most efficient heat transfer. An optional cast steel condenser inlet diffuser
may be offered, on "M" and larger condensers, in lieu of the baffle, to provide dynamic
pressure recovery and enhanced chiller efficiency. An integral sub cooler is located at the
bottom of the condenser shell providing highly effective liquid refrigerant subcooling to
provide the highest cycle efficiency. The condenser contains dual refrigerant relief valves
set at 235 psig (16.2 barg).

Waterboxes

The removable waterboxes are fabricated of steel. The design working pressure is 150
psig (10.3 barg) and the boxes are tested at 225 psig (15.5 barg). Integral steel water
baffles are located and welded within the waterbox to provide the required pass arrange-
ments. Stub out water nozzle connections with ANSI/AWWA C-606 grooves are welded to
the waterboxes. These nozzle connections are suitable for ANSI/AWWA C-606 couplings,
welding or flanges, and are capped for shipment. Plugged 3/4" (19 mm) drain and vent
connections are provided in each waterbox.
FORM 160.75-EG1 (519)
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