chiller and boiler. The inapplicable pressure
depending, upon steam or hot water, will be deleted.
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The absorber, evaporator, condenser, and generator shall comply with the
requirements of ASHRAE 15. The absorption unit shall be of the
shell-and-tube type construction. The absorber, evaporator, and condenser
shall be suitable for not less than [1,000] [1,700] kPa [150] [250] psig
waterside working pressure. The generator shall have a heating medium of
[steam] [hot water] and have a suitable working pressure of [1,000]
[1,700] kPa [150] [250] psig. The absorption unit may be enclosed in one
or two shells with removable water boxes or heads. Condenser tubes shall
be copper or copper-nickel. Generator tubes shall be copper-nickel.
Absorber and evaporator tubes shall be either copper or copper-nickel.
Tube ends shall be rolled into or silver brazed to tube sheets. All copper
or copper-nickel tubes shall be seamless and be in accordance with ASTM B
395/B 395M. The liquid cooler, within he evaporator, shall be seamless and
be in accordance with ASTM B 395/B 395M. The liquid cooler, within the
evaporator, shall be designed, constructed, tested, and certified in
accordance with ASME BPVC SEC VIII D1. [For double effect absorption
chiller[/heaters], first stage concentrator tubes shall be titanium and the
steam circuit shall comply with ASME BPVC SEC VIII D1. The header for the
double effect unit shall be designed for a steam working pressure of 1,000
kPa 150 psig and factory tested at 150 percent of design working pressure.
Double effect absorption chillers[/heaters] shall be equipped with capacity
modulation to control solution flow entering and leaving the first stage
concentrator.]
2.1.4.3
Tube Bundles
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NOTE: The selection of the double-tube bundle is a
design function where a steady demand exists for low
grade rejected heat. Where this demand does not
exist or where the heat recovery cannot be
justified, the single-tube bundle should be used.
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Provide sufficient clearance between tubes and an adequate number of
support sheets, with tubes fitted in the sheets, to prevent chafing of
tubes or crevice corrosion due to uneven tube expansion, vibration, or
pulsation. Holes in tube sheets shall not have sharp corners. Each tube
shall be removable, in one piece, through holes individually provided for
it in tube and support sheets. Water velocities through cooler, condenser,
and absorber tubes shall range from less than 0.91 to 3.66 m/s 3 to 12 fps.
Condenser shall be [single] [double]-tube bundle type.
2.1.4.4
Heads
Provide removable, welded-steel or cast-iron heads for external steam and
water connections to permit access to tubes for inspection and cleaning.
Design and test water spaces for a working pressure of not less than 1034
kPa (gage) 150 psig. Water spaces that are not subject to the ASME Code,
due to size or other limitations, shall be tested at a pressure of not less
than 1.5 times the working pressure.
SECTION 15601N
Page 22
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